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Abstract

Kaolinite Al2Si2O5(OH)4 is an abundant and inexpensive geomaterial regarded as one of the most common clay minerals in the earth's crust and the most widespread phase among the other kaolin polymorphs (halloysite, dickite and nacrite). Structurally, it is a hydrous aluminum phyllosilicate member belonging to the dioctahedral 1:1 kaolin mineral group. The particle size of the pseudohexagonal kaolinite platelets is normally <2μm (if compared to a human red blood cell of a typical diameter 6.2-8.2μm or to a virus particle of about 50nm diameter). The kaolinite platelets, either stacked together with a common booklet-like shape in a highly ordered structure (well crystallized) or disordered structure (poorly crystallized), consist of layers considered as a strong dipole of hydrophobic siloxane surface dominated by negative charges, and the other hydrophilic aluminol surface carries positive charges. Kaolinite has been used in many pharmaceutical applications as excipient or active ingredient, because it exhibits excellent physical, chemical and surface physicochemical properties. In addition to their classical pharmaceutical uses, kaolinite and its derivatives have been recently considered as a promising material in many biomedical innovation areas such as drug, protein and gene delivery based on the high interaction capacities with organic and biochemical molecules, bioadhesion and cellular uptake. Pharmaceutical kaolin grades are considerably demanded for usage as excipient in formulations of solid and semi-solid dosage forms. The most important functionalities of kaolin used as excipient are reported as diluent, binder, disintegrant, pelletizing and granulating, amorphizing, particle film coating, emulsifying and suspending agent. Because of its uninjured bioactivity, kaolinite has been also used as active agent for treatment of some common diseases. It can be topically administered as hemostatic agent, dermatological protector, anti-inflammatory agent and in pelotherapy, or orally as gastrointestinal protector, and antibacterial, antiviral, detoxification or antidiarrheal agent. With these premises, the future of kaolinite in health-care uses is strongly interesting, especially in the development of pharmaceutical and cosmetic industries. In biomedicinal investigations, it can be considered as a promising natural geomaterial for designing new derivatives that can contribute in the trials of discovering new therapeutic systems and treatment pathways of global challenge diseases such as cancer, viruses, antibiotic resistant bacteria, alzheimer, chronic skeletomuscular and geriatric diseases.

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... Recently, considerable attention has been paid to using kaolin minerals in pharmaceutical formulations because of their bio-compatibility, natural availability, and low cost [7]. Kaolin was largely used as an active pharmaceutical ingredient with different therapeutic actions (e.g., antibacterial, anti-inflammatory, dermatological protector, and antidiarrheal agent) thanks to its high specific area, sorptive capacity, rheological properties, and absence of toxicity [8]. ...
... In the last few years, kaolin has been commonly used as a gastrointestinal protector [7], and thus, it may be exploited to reduce the IND-induced gastric irritation. Kaolin was also considered as multifunctional excipient in drug formulations (amorphizing agent, diluent, binder, disintegrant, granulating, emulsifying, particle film coating, and suspending agent) [7]. ...
... In the last few years, kaolin has been commonly used as a gastrointestinal protector [7], and thus, it may be exploited to reduce the IND-induced gastric irritation. Kaolin was also considered as multifunctional excipient in drug formulations (amorphizing agent, diluent, binder, disintegrant, granulating, emulsifying, particle film coating, and suspending agent) [7]. ...
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PurposeIn this work, we investigate the effect of adding polyvinylpyrrolidone (PVP K30) to the binary solid dispersion (indomethacin/kaolin) on the formation of physically stable amorphous drug. This aims to profit more effectively from the therapeutic effect of kaolin in the solid dosage forms of indomethacin.Methods Binary mixtures (indomethacin/kaolin) were ball milled at room temperature (≈ 25 °C) in presence of PVP K30 at different weight ratios (w/w). The characterization of the obtained materials was carried out using X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), high-performance liquid chromatography (HPLC), differential scanning calorimetry (DSC), and 13C MAS NMR spectroscopy.ResultsResults have shown that indomethacin (IND) interacted with kaolin and PVP K30 in solid state via hydrogen bonds without any polymorphic transformations or chemical degradation. The PVP seems to play a role of linker between drug and kaolin leading to physical stability enhancement of amorphous IND even under high stress conditions (RH = 75% and T = 40 °C for 3 months). Such ternary system (IND/kaolin/PVP) has shown a considerable improvement of drug solubility at T = 37 ± 0.5 °C and pH = 7.0 compared to the binary solid dispersion (IND/kaolin).Conclusions The addition of PVP to the solid dispersion (IND/kaolin) was advantageous not only in terms of physical stabilization of the amorphous IND but also made it possible to overcome the solubility challenges associated with the presence of kaolin.
... Kaolinite is the most common nanoclay in the kaolin group. Usually, kaolinite takes the form of stacked pseudohexagonal platelets with a particle size <2 lm (Fig. 4A, B) [28]. Each platelet is an arrangement of two sheets, namely an aluminum octahedral sheet (aluminol surface) with a silicon tetrahedral sheet (siloxane surface) stacked one above the other. ...
... Together, these sheets create a strong dipole structure, with the individual platelets of kaolinite strongly bound together by hydrogen bonds and ionic bonds. However, the edges of these platelets show a pH-dependent charge, due to the protonation or deprotonation of the OH groups [28]. Given that few or no ionic substitutions are present within the kaolinite structure, this nanoclay shows two different types of charge, the permanent charge on its surface, and pH-dependent charges. ...
... We envisage a wider use of nanoclays for oral delivery in the form of tablets. We also think that the topical administration of nanoclays on skin has a potential to be translated to clinical research due to their ethnopharmacological use in pelotherapy (application of medicinal thermal muds compromising geomaterials and thermo-mineral medicinal water through the skin) [28] and the use of certain types of nanoclays as functional excipients in cosmetic formulations [25,35]. The transdermal administration (which implicates systemic absorption), or even the intratumoral administration of drug-clay formulations may be applied in the treatment of solid cancers (e.g., skin cancers). ...
Article
Cancer remains one of the deadliest diseases, and its effective diagnosis and treatment remains challenging; therefore, progress in earlier detection and improved therapeutics are urgently required. Conventional chemotherapy has only limited efficacy, suffers from non-specific toxicity and the induction of chemoresistance. Prospective templates for these are natural materials such as nanosized clay mineral structures of different shapes (platy, tubule, spherical, and fibrous) with tunable physicochemical, morphological, and structural properties. Their submicron size, individual morphology, high specific surface area, enhanced adsorption ability, cation exchange capacity, and multilayered organization of 0.7-1 nm thick single sheets have attracted considerable interest as multifunctional biocompatible nanocarriers with versatile applications in cancer research, diagnosis, and therapy. The most common nanoclay minerals studied for oncology are kaolinite, halloysite, montmorillonite, laponite, bentonite, sepiolite, palygorskite, and allophane. These multilayered minerals can act as nanocarriers (with a typical drug load of 1-10 wt. %) for improved dispersibility, stabilization, sustained controlled release, and the efficient transport of a wide range of anticancer drugs to the tumor site. Nanoclays having both positive and negative surfaces possess the potential to transport proteins and DNA/RNA. Nanoclays can serve as a platform for phototherapeutic agents. Several surface engineering strategies have been devised to develop clays with biofunctionality that could benefit cancer clinical practice. This review explores the potential of nanoclays as unique crystalline materials with applications in cancer research, diagnosis, and therapy.
... The wide application of Kaolinite can be seen from an extensive review by Awad et al. in 2017 [14]. Kaolinite which is chemically Al 2 Si 2 O 5 (OH) 4 is one of the most abundant and inexpensive clay mineral in the earth's crust. ...
... Specifically, kaolin is seen to enhance the activity of coagulation factor XII that in turn activates coagulation factor XI and prekallikrein. Therefore, kaolin has been used in various commercially available wound dressings and hemostatic dressings such as QuikClot Combat Gauze™ (QCG), Quik-Clot Combat GauzeXL (QCX), QuikClot Combat Gauze TraumaPad (QCTP), and QuikClot® Interventional which are FDA approved products [7,14]. Kaolinite has also been reported to be used in preparations and formulations concerning inflammation (Caloplast, KL kaolin), dermatological concerns (kerodex, REINOL Aquagard, CALMA mask, Lactocalamine lotion), gastrointestinal and anti-diarrhoeal agents (ASDA Tablets, Entrocalm, Boots Kaolin, Kaopectate, Kaomix suspension, Kaolin Antacil), anti-bacterial material, antiviral agents, and anti-tumor compounds [14]. ...
... Therefore, kaolin has been used in various commercially available wound dressings and hemostatic dressings such as QuikClot Combat Gauze™ (QCG), Quik-Clot Combat GauzeXL (QCX), QuikClot Combat Gauze TraumaPad (QCTP), and QuikClot® Interventional which are FDA approved products [7,14]. Kaolinite has also been reported to be used in preparations and formulations concerning inflammation (Caloplast, KL kaolin), dermatological concerns (kerodex, REINOL Aquagard, CALMA mask, Lactocalamine lotion), gastrointestinal and anti-diarrhoeal agents (ASDA Tablets, Entrocalm, Boots Kaolin, Kaopectate, Kaomix suspension, Kaolin Antacil), anti-bacterial material, antiviral agents, and anti-tumor compounds [14]. ...
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Biomedical composites or biocomposites refer to the artificially synthesized heterogeneous materials that are composed of two or more ingredients with different chemical and physical nature where one component is a biopolymer. These composites are shown to have various biomedical applications ranging from bone tissue engineering, dental restorations, wound healing, and drug delivery. Though various inorganic materials such as hydroxyapatite and β-tricalcium phosphate have been tested and used clinically for bone regeneration and restoration, they have their own advantages and drawbacks. Nanosilicates are one of the most abundant natural inorganic mineral components present in the earth’s crust, in the form of mineral clay, which have recently gained importance in modern-day biomedical research. Montmorillonite, Kaolinite, and Halloysite are the three common natural nanoclays being used in various biomedical research. Laponite® is the most used synthetic nanosilicate used for various biomedical research. Though mineral clays have been used directly and extensively in traditional medicines for various ailments, their nanosilicate forms separately have shown promising results in bone tissue engineering, dental restoration, drug delivery applications, and wound healing research.
... Kaolin has thus been identified as one of the significant hemostatic agents, which could substantially promote blood coagulation [16]. Kaolin, often known as China clay, principally comprises kaolinite and aluminium silicate [16]. ...
... Kaolin has thus been identified as one of the significant hemostatic agents, which could substantially promote blood coagulation [16]. Kaolin, often known as China clay, principally comprises kaolinite and aluminium silicate [16]. Given that negative charges on the kaolin surface could substantially promote blood coagulation, kaolin was successfully implemented as active material in surgical hemostasis. ...
Article
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The predominant impediments to cutaneous wound regeneration are hemorrhage and bacterial infections that lead to extensive inflammation with lethal impact. We thus developed a series of composite sponges based on polyvinyl alcohol (PVA) inspired by marjoram essential oil and kaolin (PVA/marjoram/kaolin), adopting a freeze–thaw method to treat irregular wounds by thwarting lethal bleeding and microbial infections. Microstructure analyses manifested three-dimensional interconnected porous structures for PVA/marjoram/kaolin. Additionally, upon increasing marjoram and kaolin concentrations, the pore diameters of the sponges significantly increased, recording a maximum of 34 ± 5.8 µm for PVA-M0.5-K0.1. Moreover, the porosity and degradation properties of PVA/marjoram/kaolin sponges were markedly enhanced compared with the PVA sponge with high swelling capacity. Furthermore, the PVA/marjoram/kaolin sponges exerted exceptional antibacterial performance against Escherichia coli and Bacillus cereus, along with remarkable antioxidant properties. Moreover, PVA/marjoram/kaolin sponges demonstrated significant thrombogenicity, developing high thrombus mass and hemocompatibility, in addition to their remarkable safety toward fibroblast cells. Notably, this is the first study to our knowledge investigating the effectiveness of marjoram in a polymeric carrier for prospective functioning as a wound dressing. Collectively, the findings suggest the prospective usage of the PVA-M0.5-K0.1 sponge in wound healing for hemorrhage and bacterial infection control.
... In the field of dermatology and cosmetics, their use is equally important and due to the ingredients they contain, they prove to be beneficial against skin lesions in various parts of the body [1,13]. In addition, they act locally as antiseptics [14], disinfectants [14] anti-inflammatory [14][15][16], as dermatological protections [14,15,17], as well as local anesthetics [13,18,19]. They have been used as carriers and have great interest, especially when they are combined with metals known for their antimicrobial and antibacterial properties [19][20][21]. ...
... In the field of dermatology and cosmetics, their use is equally important and due to the ingredients they contain, they prove to be beneficial against skin lesions in various parts of the body [1,13]. In addition, they act locally as antiseptics [14], disinfectants [14] anti-inflammatory [14][15][16], as dermatological protections [14,15,17], as well as local anesthetics [13,18,19]. They have been used as carriers and have great interest, especially when they are combined with metals known for their antimicrobial and antibacterial properties [19][20][21]. ...
Article
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Pharmaceutical grade bentonite, containing a high amount of montmorillonite, enriched with zinc (Zn) or copper (Cu) (ZnBent and CuBent, respectively) was used as the main component for the creation of formulations for cutaneous use and tested for their antimicrobial capacity. Bentonite (Bent) with added phenoxyethanol (PH) as a preservative and unmodified bentonite were used as control groups. The mineralogical composition, structural state, and physical or chemical properties, before and after the modification of the samples, were characterized utilizing X-ray Diffraction Analysis (XRD), Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Fluorescence (XRF) techniques, and Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM, SEM-EDS) analyses. In addition, the profile of zinc and copper concentration from two types of surfaces ZnBent and CuBent, and into Phosphate-Buffered Saline (PBS) are discussed. Finally, the formulations in the form of basic pastes were challenged against bacteria, molds, and yeasts, and their performance was evaluated based on the European Pharmacopeia criteria. The Cu-modified bentonite performed excellently against bacteria and yeasts, while the Zn-modified bentonite only showed great results against yeasts. Therefore, Cu-modified bentonite formulations could offer antimicrobial protection without the use of preservatives.
... It can withstand heating to 400 ⁰ C, below the dehydroxylated limit, and is resistant under strong acidic conditions (Jozefaciuk and Bowanko, 2002;Liu et al., 2015). In the preformulation stage, natural kaolinite-rich clay deposits (i.e., kaolin) can be easily purified to achieve pharmaceutical grade kaolin commonly used as excipient and active ingredient in many healthcare applications (Awad et al., 2017a). In the targeted formulation of silver-kaolinite nanocomposites, previous studies worked on loading of silver nanoparticles onto the kaolinite platelets by wet methods for mechanochemical dilation of kaolinite basal spacing and silver precipitation with thermal or chemical reduction (using chemical reducing agents) from aqueous solutions of silver salts such as AgNO 3 (Patakfalvi et al., 2003;Cabal et al., 2010;Burridge et al., 2011;Moosa et al., 2019). ...
... The finer particles were then decanted, centrifuged, washed three times and dried at 60 • C overnight. The resulting ultrafine white kaolin powders were then analyzed, proving to comply with pharmaceutical grade specifications (Awad et al., 2017a(Awad et al., , b, 2020. They were therefore suitable for synthesis of the targeted silver-kaolinite nanocomposites. ...
Article
The present research aims to enhance the antimicrobial activity of kaolinite surfaces by a one-step cost-effective and energy-efficient dry thermal reaction, producing an antibacterial and antifungal silver-kaolinite (Ag-Kao) nanocomposite agent. Pharmaceutical grade kaolin powder samples, with variable kaolinite structural order-disorder degree, were homogeneously mixed with silver nitrate in a proportion 1:4 AgNO3 : kaolin (w/w) and sintered at 400 °C for 30 minutes. The composition, microstructure, microtexture and surface characteristics of the pyro-fabricated nanocomposites were characterized by XRD/XRF diffractometry, differential scanning calorimetry DSC, FT-IR spectroscopy, TEM/EDX, zeta potential (mV) measured within the 2 – 12 pH range, and BET method. Physicochemical stability was evaluated by silver dissociation testing under close-neutral and acidic conditions with Ag content assay using ICP-OES. The resulting Ag-Kao nanocomposites exhibited bulk silver contents ranging from 9.29 % to 13.32 % with high physicochemical stability in both neutral and acidic mediums (Ag dissociation rate < 0.5 % in 5 days). Ag nanocrystals exhibited particle sizes ranging from 5 to 30 nm, which were embedded and reinforced within the kaolinite matrix. The sizes of the Ag nanocrystals and their distribution patterns on the edges and faces of kaolinite platelets were controlled by the structural order-disorder degree. Highly ordered kaolinites (Hinckley Index, HI > 1) produced platelet edge-clustered silver nanocrystals due to the abundance of the dangling hydroxyls on platelet edges, while the highly disordered kaolinite (HI < 1) provided homogeneous platelet basal-doped silver nanocrystals due to the presence of some residual charges by exposed basal hydroxyl groups with interplatelet silver diffusivity. At pH 2, the magnitude of the positive surface charge was influenced by the silver nanocrystal size. Nanocomposites with the smallest silver nanocrystals (10 – 5 nm) exhibited the highest positive zeta potential (+15.2 mV to +17.0 mV), while those with larger silver nanocrystals (up to 30 nm) indicated lower positive zeta potential values (+9.5 mV to +3.6 mV). Under the same testing conditions using the Mueller-Hinton broth microdilution method, the raw kaolin samples did not show any significant antimicrobial activity, while all the pyro-fabricated Ag-Kao nanocomposite samples showed potent antibacterial and antifungal activity at low doses (MIC range 0.1 – 0.0125 mg/mL). Therefore, modulation of the effective electrostatic surface charge of the kaolinite platelets, via thermal doping of silver within their basal planes and edges, was found to be strongly dependent on the pH as well as the size and microtexture of the silver nanocrystals (mainly controlled by the order-disorder degree HI). The resulting modified nanostructure, with physicochemical stability and the efficient surface properties of the designed pyro-fabricated nanocomposite, led to an enhanced synergistic biophysical antimicrobial activity.
... Oral pathogens like E. coli, Bacillus subtilis, and klebsiella pneumonia are effectively killed by kaolin/iron-porphyrin hybrid. Nano-composite of silver-kaolinite also demonstrated to have antibacterial property [109]. They use clay as an adsorbate to remove pathogenic viruses and certain phages are under investigation since the twentieth century. ...
... Kaolin also used to absorb excess moisture, oily secretion, surface lipids, and superficial toxin from the skin surface to prevent acne, blackheads, bacterial, and fungal infections. Even they are used for insect bites to give relieving effect [109]. ...
Chapter
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Clay has its widespread applications in pharmaceuticals from ancient world to modern era. It is one of the excellent excipients present in the commercially available pharmaceuticals. Its use in many of dosage forms viz. in suspension, emulsion, ointments, gels, tablet and as drug delivery carrier as suspending agent, emulsify-ing agent, stiffening agent, binder, diluent, opacifier, and as release retardant have been explored in many studies. Variety of minerals is used as both excipient and as an active ingredient; among that kaolinite, talc, and gypsum are important. Their inertness, low toxicity, versatile physiochemical properties and cost effectiveness has increased its usage in pharma industries. Many minerals have its own pharmacological action as antacid, anti-bacterial, anti-emetic, anti-diarrheal agent and as skin protectant etc. Their unique structure which helps them to absorb material onto their layered sheets has opened a wide variety of applications in drug delivery. The understanding of surface chemistry and particle size distribution of clay minerals has led the pharmaceutical field in many directions and future perspectives.
... The MPs were irregularly shaped, to which many small particles attached, whereas kaolin appears to form stacked plate-like agglomerates. This observation is in accordance with its actual shape, therewith connected is the high adsorption potential for organic molecules (Awad et al., 2017). Moreover, the size fractions of both particles were not identical despite the congruent particle distribution for the size-range 8-18 μm (Fig. S1). ...
... Although the worm tolerates a wide range of physico-chemical sediment properties (Ankley et al., , 1994Ingersoll et al., 1995), it reproduces better in fine-sized sediments (Leppänen & Kukkonen, 1998a;Sardo et al., 2007). We assume that kaolin provides more favorable conditions as it has a high capacity to bind organic molecules (Awad et al., 2017) and thereby, provides nutritional value. ...
Article
Microplastics (MPs) as complex synthetic pollutants represent a growing concern for the aquatic environment. Previous studies examined the toxicity of MPs, but infrequently used a natural particle control such as kaolin. The cause of toxicity, either the physical structure of the particles or chemical components originating from the MPs, has rarely been resolved. Moreover, the ecotoxicological assessment of biodegradable plastics has received little attention. To narrow down the main driver for toxicity of irregular biodegradable MPs, we conducted a series of 28-days sediment toxicity tests with the freshwater oligochaete Lumbriculus variegatus and recorded the number of worms and dry weight as endpoints. Therefore, MPs containing several biodegradable polymers were either mixed with the sediment or layered on the sediment surface with concentrations from 1 to 8.4% sediment dw⁻¹. Kaolin particles were evaluated in parallel as particle control. Furthermore, aqueous leachates and methanolic extracts as MP equivalents as well as solvent-treated, presumably pure MPs were investigated after mixing them into the sediment. Our results reveal that MP mixed with the sediment induced stronger adverse effects than layered MP. Kaolin particles caused no adverse effects. In contrast, they enhanced dry weight in both applications. The impact of aqueous leachates was comparable to the control without MPs, whereas methanolic extracts affected the worm number at the highest concentration with 100% mortality. Solvent-treated, presumably pure MP resulted in mostly higher worm numbers when compared to untreated MPs mixed into the sediment. This study demonstrates that MPs mixed into the sediment affect L. variegatus more than MPs that are layered on the sediment surface. Kaolin as a natural, fine-sized particle control created somewhat favorable conditions for the worm. The main driver for toxicity, however, proved to be chemicals associated with the plastic product and its previous content.
... Kaolinite (Kao) is a 1:1 layered dioctahedral phyllosilicate. Kao could serve as a suitable inexpensive excipient, and the interaction between Kao and drugs may be useful in the design of modified drug delivery systems [13]. The most important functionalities of Kao in pharmaceutical formulation are as a diluent, binder, disintegrant, pelletizing and granulating, amorphizing, particlefilm coating, emulsifying, and suspending agent [13]. ...
... Kao could serve as a suitable inexpensive excipient, and the interaction between Kao and drugs may be useful in the design of modified drug delivery systems [13]. The most important functionalities of Kao in pharmaceutical formulation are as a diluent, binder, disintegrant, pelletizing and granulating, amorphizing, particlefilm coating, emulsifying, and suspending agent [13]. Similar to talc, 5-fluorouracil, sorption on Kao could be on the external surfaces and in the interlayer spaces after being modified with dimethyl sulfoxide [14]. ...
Article
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Excipients play an important role in pharmaceutical formulations. Many clay minerals, because of their large specific surface area and inert behaviour in reactions with active ingredients, are commonly used as excipients. In this study, the uptake of ranitidine (RT), the active ingredient of Zantac, on and released from palygorskite (Pal), kaolinite (Kao), and talc was evaluated under different physicochemical conditions. The results showed that the uptake of RT on these minerals was limited to the external surface areas only. Cation exchange and electrostatic interactions were responsible for the RT uptake on Pal and Kao, resulting in a monolayer sorption. In contrast, multilayer RT uptake was found on the talc surfaces. Under different desorbing conditions, significant amounts of sorbed RT remained on the solid surface after 5 h of desorption. The results suggest that the sorptive interactions between the active ingredients and the excipients may not be neglected in pharmaceutical formulations, should these minerals be used as additives and/or excipients.
... Kaolin is a hydrated two-dimensional (2D) aluminosilicate clay mineral which has been extensively used in biomedical related applications such as an activating agent for blood clotting [13], as an ingredient for operation hemostasis [14] and also used in drug delivery systems for prolonged-release, especially of basic drugs because it can act as an active excipient in pharmaceutical dosage forms to increase the efficiency and bioavailability of drug molecules [15]. In fact their medicinal utilities have been discovered by many traditional civilizations (Egyptians, Assyrians, Babylonians, Indians, Chinese), Greeks, Romans and medieval Arab Muslims till the recent times [16]. ...
Article
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Objective: The objective of this study is to fabricate sodium alginate (SA)/gum ghatti (GG) microbeads intercalated with Kaolin (KA) nano clay for the sustained release of curcumin (CUR). Methods: The microbeads were prepared by a simple ionotropic gelation technique. The developed beads were characterized by fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (X-RD), and scanning electron microscopy (SEM). Swelling studies and in vitro release studies were investigated under both pH 7.4 and pH 1.2 at 37 °C. Results: The developed microbeads were characterized by FTIR, which confirms the interaction between CUR, polymeric matrix and KA. DSC and XRD analysis reveals that the CUR has molecularly dispersed in the polymer matrix. In vitro results illustrated that microbeads were influenced by the pH of test media, which might be suitable for intestinal drug delivery. The drug release mechanism was analyzed by fitting the release data into different kinetic equations and n values are obtained in the range of 0.609-0.640, suggesting that the developed microbeads showed the non-Fickian diffusion type drug release. Conclusion: These results clearly illustrated that the developed KA intercalated polymeric microbeads are potential drug carriers for the controlled release of CUR.
... Kaolinite is 16% of Puriton ® and is widespread in the world. It has several biological efficacies, such as antibacterial effects, anti-viral effects, and detoxification [27]. Qin et al. reported that Fe 3+ -saturated montmorillonite could suppress bacterial activity in municipal wastewater effluents [28]. ...
Article
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In 2016, infectious microbes were one of the leading causes of death, especially in developing countries. Puriton® is a mineral mixture consisting of biotite, kaolinite, montmorillonite, serpentine, clinochlore, and vermiculite, and evaluated antimicrobial activity in vitro and safety in vivo. Nine pathogens and opportunistic bacteria, namely Salmonella typhimurium, Escherichia coli, Pseudomonas aeruginosa, Alcaligenes faecalis, Staphylococcus aureus, Enterococcus faecalis, Micrococcus luteus, Mycobacterium smegmatis, and Bacillus subtilis, and the two viruses Zika and Influenza A/Duck/MN/1525/81 were used. A 26-week oral repeated safety study of Puriton® was conducted. Puriton® suppressed the bacterial proliferation, with a minimum proliferative rate of 91.1% in B. subtilis ATCC6633. The virucidal efficacy of Puriton® against Zika virus after 4 h and 18 h of contact time was significant in all groups treated with Puriton®. Twenty-six-week repeated oral administration of Puriton® was considered safe based on physiological results, such as behavior and blood cells/chemistry, and histopathological changes in the brain, heart, kidney, liver, and lung. We concluded that Puriton® exerted bactericidal and virucidal efficacies and was safe for 26-week repeated oral administration.
... Biological purification techniques are more economical, eco-friendly, not energy-intensive, and maintains the crystal structure of kaolin clay to a large extent [30], [31] but a very slow process for industrial mass production. Beneficiated kaolin can be categorized into two types: hydrous kaolin and calcined kaolin and their uses for specific applications, including paper, ceramics and refractories, plastics, rubber, adhesives, fiberglass, paints, inks, pharmaceuticals and cosmetics, and cracking catalyst or cement industries [32]. ...
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Kaolin (china clay) is a rock material that is very rich in kaolinite. A kaolin ore from Debre Tabor, Ethiopia containing 59.2 wt.% SiO 2 , 24.9 wt.% Al 2 O 3 , 2.4 wt.% Fe 2 O 3, and 8.22 wt.% loss on ignition (LOI) was physically beneficiated, chemically leached, and thermally treated for possible industrial use, especially for ceramic membrane fabrication. The leaching experiments were carried out using oxalic acid solutions as leaching reagents for the iron extraction process. The effect of acid concentration, reaction temperature, and contact time on iron leaching was investigated. It was determined that the rate of iron extraction increased with the oxalic acid concentration, leaching temperature, and contact time. A substantial reduction of iron oxide (2.4 to 0.36 wt. %) from the raw kaolin was observed at operating conditions of 2.0 M oxalic acid, the temperature of 120°C, and contact time of 120 min. A maximum kaolin whiteness index of 81.4 % was achieved through this leaching process. Finally, the physically beneficiated, chemically leached, and thermally treated kaolin raw material was used to fabricate a low - cost kaolin - based ceramic membrane. After firing at 1100°C the ceramic membrane was found to have a mass loss of 11.04 ± 0.05%, water absorption of 8.9 ± 0.4 %, linear shrinkage of 14.5 ± 0.05%. It was demonstrated to be chemically stable, having less than 3 % mass loss in acid solution, and less than 1 % mass loss in alkali solution. The newly developed membranes have thus properties comparable to commercial ceramic membranes.
... The membrane surface zeta potential decreases at the higher pH values until the isoelectric point (pH 6.2) and is charged negatively above this value. The membrane's net charge around the isoelectric point is nearly zero, where the membrane functions as a nonpolar sheet [33]. ...
Article
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Hybrid nanostructure materials derived from activated metakaolinite are of growing importance due to their intriguing structural/functional properties and promising biomedical/environmental applications, especially designing desalination membranes. Herein, we report procedures to design and fabricate membranes based on waste polyethylene/porous activated-metakaolinite thin film nanocomposites (WPE/PAMK-TFN). It has been devoted to improving water desalination processes, where efficient removal of trace level (~250 ppm) of toxic heavy metals such as Cd(II), Pb(II), and Cu(II) ions from synthetic wastewater solutions was highly accomplished. Physicochemical techniques such as X-ray diffraction (XRD), surface analysis (BET), and Fourier transform infrared spectroscopy (FTIR) have been extensively employed to elucidate the structure/composition of the prepared nanomaterials. The effect of concentration (0–0.5 wt%) of porous activated-metakaolinite (PAMK) on water permeation was investigated. The results obtained revealed that 0.5 wt% of PAMK clay particles produced the highest dispersion, as evident by SEM images of the nanocomposite membranes. Significantly, the constructed membrane showed marked improvements in porosity, hydrophilicity, and hydraulic resistance. Moreover, elemental mapping studies have confirmed the intercalation of activated bentonite clay within the polymer matrix. The obtained results demonstrated that increased flux and rejection capability of membranes occurred at high clay dosage. In contrast, the low rejection capability was observed at either lower pH and higher initial feed concentrations. Ultimately, for 250 ppm of Cd(II), Pb(II), and Cu(II) ions, the constructed membranes showed maximum removal capability of 69.3%, 76.2%, and 82.5% of toxic cations, respectively.
... Alkaram et al. (2009) studied the adsorption of phenol by Mt. and Kaol modified with two surfactantshexadecyltrimethylammonium bromide, (HDTMA, long chain modifier) and phenyltrimethylammonium bromide (PTMA, short chain modifier) and reported that the modified clays were much more effective in phenol removal than unmodified samples. Kaolinite is also widely used in many pharmaceutical applications as an excipient or active ingredient (Awad et al., 2017). Recently, non-swelling clays with low CEC (Kaol and illite) have been considered as adsorbents for aflatoxin B 1 (Kang et al., 2016). ...
Article
A natural kaolin from Serbia was modified with different amounts of octadecyldimethylbenzyl ammonium (ODMBA) - (25, 50 and 90% of kaolin cation exchange capacity). Samples were denoted as OKR-25, OKR-50 and OKR-90. Several methods (FTIR spectroscopy, thermal analysis, zeta potential measurements, and N2 physisorption) were used for characterization of the organokaolinites. Adsorption of the common mycotoxins - ochratoxin A (OCHRA) and zearalenone (ZEN) by the organokaolinites was investigated at different levels of solid phase in suspension, different initial mycotoxin concentrations and different pH values. The natural kaolin was not effective in binding OCHRA or ZEN. Adsorption of both mycotoxins by organokaolinites increased with increasing amounts of solid phase as well as with increasing levels of surfactant on the kaolin surface. OCHRA and ZEN adsorption by all organokaolinites followed non-linear adsorption isotherms, at pH 3, 7 and 9. The maximum adsorption capacity for OCHRA adsorption was at pH 3 (4.8 mg/g for OKR-25, 26.7 mg/g for OKR-50 and 39.2 mg/g for OKR-90) that was calculated from the Langmuir model. Much lower OCHRA adsorption capacities were found at pH 7 and 9 (from 0.8 mg/g to 6.9 mg/g at pH 7 and from 1.1 mg/g to 4.6 mg/g at pH 9). The following adsorption capacities for ZEN were obtained from the Langmuir isotherms, at pH 3: 4.5 mg/g for OKR-25, 12.0 mg/g for OKR-50 and 13.5 mg/g for OKR-90. At pH 7, adsorption of ZEN was 5.7 mg/g for OKR-25, 15.3 mg/g for OKR-90 and 14. 4 mg/g for OKR-90. At pH 9, ZEN adsorption capacities were 2.4, 14.1 and 8.1 mg/g for OKR-25, OKR-50 and OKR-90, respectively. Thus, at the lowest amount of ODMBA at the kaolin surface, adsorption of ZEN was similar at pH 3 and 7, while a slightly lower value was obtained for its adsorption at pH 9. With increasing amounts of organic phase at the kaolin surface, the adsorption of ZEN was practically independent of pH. Adsorption of both mycotoxins was dependent on the amount of ODMBA ions at the kaolin surface as well as on their forms in solution.
... Kaolinite is a layered clay mineral with the composition Al 4 Si 4 O 10 (OH) 8 per unit cell, which is overall neutral at pH ~ 5.5 (Martorell et al., 2010) and consists of an "octahedral" Al(o) sheet and a "tetrahedral" Si(t) sheet (Awad et al., 2017). (001)] surfaces were investigated for adsorption. ...
Article
Retardation of Cd(II) migration is an ongoing concern for environmental remediation, but a prevalent obstacle of the procedure originates from the lack of an atomic-scale description of the inherent mechanism for Cd(II) adsorption at mineral-water interfaces. Herein, we performed first-principles calculations and ab initio molecular dynamics (AIMD) simulations to explore the adsorption mechanism of Cd(II) on the basal surfaces of kaolinite. Representative monodentate and bidentate Cd(II) complexes were constructed on the Kln−Al(001) and Kln−Si(001̅) surfaces. The results showed that bidentate coordination of Cd(II) on the Kln−Al(001) surface was superior to all other studied models due to the favorable formation energy and better agreement with EXAFS data. The calculated electron density difference revealed the charge transfer from surface oxygen (Os) to Cd(II) upon adsorption. In particular, partial density of states (PDOS) analysis indicated that the Cd−Os bond exhibited covalent characteristics, attributed to the overlaps of Cd-5p and Os-2p orbitals in the valence band. Furthermore, radial distribution functions supported by AIMD simulations were employed to confirm the structural features of Cd(II) coordination shell at kaolinite-water interfaces. This theoretical study provides insightful guidance for future Cd(II) research to improve current assessments of contaminant remediation.
... Lipid peroxidation and oxidative stress lead to increased membrane permeability [222]. Furthermore, some kaolin minerals have photocatalytic properties [223,224] and may induce photodegradative damage to bacteria. Finally, an altered pH and oxidation state of the microenvironment can hamper bacteria [225,226] and further result in the combined action of Al and Fe on membranes and on intracellular proteins [203,227]. ...
Article
Intact, ‘healthy’ soils provide indispensable ecosystem services that largely depend on the biotic activity. Soil health is connected with human health, yet, knowledge of the underlying soil functioning remains incomplete. This review highlights selected services, i.e. (i) soil as a genetic resource and hotspot of biodiversity, forming the basis for providing (ii) biochemical resources and (iii) medicinal services and goods. Soils harbour an unrivalled biodiversity of organisms, especially microorganisms. Some of the abilities of autochthonous microorganisms and their relevant enzymes serve (i) to improve natural soil functions and in particular plant growth, e.g. through beneficial plant growth-promoting, symbiotic and mycorrhizal microorganisms, (ii) to act as biopesticides, (iii) to facilitate biodegradation of pollutants for soil bioremediation and (iv) to yield enzymes or chemicals for industrial use. Soils also exert direct effects on human health. Contact with soil enriches the human microbiome, affords protection against allergies and promotes emotional well-being. Medicinally relevant are soil substrates such as loams, clays and various minerals with curative effects as well as pharmaceutically active organic chemicals like antibiotics that are formed by soil microorganisms. By contrast, irritating minerals, soil dust inhalation and misguided soil ingestion may adversely affect humans. This article is part of the theme issue ‘The role of soils in delivering Nature’s Contributions to People.
... Subject to sodium carbonate treatment, affordable and effective kaolinitic clays could be used as antacids [59]. Thus, kaolinite is a gastrointestinal protector [60,61]. Their therapeutic action is based on their high specific area and adsorption capacity [62]; they adhere to the gastric and intestinal mucosa and protect them, and can absorb toxins, bacteria, and even viruses [63]. ...
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This study aims to characterize and estimate risk assessment associated with geophagic materials consumption in Maputo city (Mozambique). Samples were collected in extraction mines, unprepared and prepared ones, and in Maputo markets. Fractions < 2 mm (total consumed material) and < 63 μm were analyzed to determine pH, EC, OM, chemical composition (XRF), and mineral phases present (XRD). The results revealed pH from slightly acidic to slightly alkaline, and electrical conductivity ranging from 13 to 47 μS/cm in mine unprepared and prepared samples, while 264–465 μS/cm in sampled sold in markets. Organic matter content was <2.76%, except in one sample (8.14%), suggesting a potential risk of containing bacteria. Textural analysis revealed that sand-size particles were more representative in all samples (57.2–93.02%). Mineralogical phases identified in the consumed sample were ranked quartz (>60%) > Fe oxides/hidroxides > phyllosilicates (micas and kaolinite) > feldspars, suggesting a risk of dental enamel damage and perforation of the sigmoid colon. The chemical concentration of some elements was higher than recommended daily dose, suggesting a potential risk. However, geophagic materials’ chemical composition does not pose a carcinogenic risk.
... Kaolins are used in several industries, including the construction, pharmaceutical, cosmetic industries amongst others (Heckroodt, 1991;Siddiqui et al., 2005;Matike et al., 2011;Obaje et al., 2013;Tassongwa et al., 2014). In the pharmaceutical industry, kaolin is used as excipient or active ingredient due to its excellent physical, chemical and surface physicochemical properties (Awad et al., 2017). Four types of bricks can be made from kaolin in the construction industry; these include common bricks, vertically perforated bricks, roofing tiles, masonry bricks, and hollow products (Dondi et al., 1992). ...
Article
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The geochemistry and diagnostic evaluation of Cretaceous-Tertiary kaolins in the Douala Sub-Basin in Cameroon were carried out in order to determine their potential industrial applications. The mineralogical, physical, physico-chemical and geochemical characteristics of the kaolins were determined. Quartz and kaolinite are the most dominant mineral phases in bulk kaolins (means of 45.25 and 33.90 wt%, respectively); whereas in the <2 μm fraction, kaolinite is the most dominant mineral phase (mean of 72.17 wt%). The texture of half of the samples is sandy loamy clay or sandy loam texture, and the colour from white to light reddish brown. The moisture content is generally <2 wt% in all the size fractions. The kaolins have an acidic pH, and the electrical conductivity is below 55 μS/cm. The major oxides geochemistry shows that the most abundant major oxides are silica and alumina, followed by iron oxide and titania. As physical, physico-chemical and geochemical characteristics of kaolins determine their potential industrial applications, these were inferred. Based on the interpretation of the results, the investigated kaolins could be used in the pharmaceutical, construction, pottery and cosmetics industries.
... 1989). Currently, clay materials nd place in many industrial, agricultural, civil, environmental and sanitary applications (Ciullo, 1996;Murray, 1999;Carretero et al., 2013;Awad et al., 2017bAwad et al., , 2018. They participate in economic (Kühnel, 1990;Ekosse, 1994;Murray, 2000) and technological development (Njopwouo, 1984;Martin, 1994Martin, , 2005Harvey and Murray, 1997). ...
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Forteen clay samples collected from three kaolin deposits (Tamazert, Hadj Ali and Chekfa; NE Algeria) are characterized by several techniques in order to compares them to somes kaolins used in industry especially that used in ceramics. All the samples were investigated by X-ray diffraction, Infrared absorption spectroscopy, thermal analysis (TG), plasticity, environmental scanning electron microscopy and chemical major elements analysis. The bulk mineralogical composition of all clays samples is dominated by kaolinite (21-75%), illite/ muscovite (33-76%) and quartz (7-21%). K-feldspar and plagioclase are only present in Chekfa and Hadj Ali clays with small amounts. Clay fraction (< 2µm) dominated by kaolinite and illite (98%). Chlorite and smectite are present in some samples of Chekfa and Hadj Ali clays with insignificant amount (˂1%). The particles-size distribution of all samples showed the abundance of sandy silt fraction (28-63%) and silty sand (39-64%) with moderate clayey fraction (2-7%). The chemical composition showed variable amounts of SiO2 (59-68%), Al2O3 (18-39%), Fe2O3 (.26-1.38%) and TiO2 (0.34-0.69%) in accordance with the free quartz in all studied samples. Plasticity-index (7.5-7.9%), Specific surface (28-47m2) and Cation exchange (5-11meq/100g) values are moderate in all samples. Given these properties, these clays may be suitable in bricks and ceramic product.
... In the observable morphology scale, the assembly of a layer formed of octahedra to a layer formed of tetrahedra forms is called a leaflet. The surfaces of these single sheets have hydroxide and oxygen atoms which allow water molecules to be inserted between the sheets (Awad et al., 2017;Awad et al., 2019). Figure 1 displays the hexagonal sheets, on native kaolin clay. ...
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Ceramic is among the complicated materials to use in the design of fine objects. Complex shapes without any major defect are not easy to produce. In most of the cases, the production of ceramic parts is the results of three steps. Firstly, the “sculpture” of the raw piece by adding raw materials to lead to the final object. Secondly, the “drying” and finally the “high temperature oven-dry” of the dried raw object to transform the granular dough into a nice consistent compact material. Exploiting the special characteristics of ceramic is not only a thing of the past. Nowadays new possibilities, i.e., shapes and styles, can be offered in the use of ceramics, and especially where it concerns the application of the Additive Manufacturing (AM) concept. The combination of Computer Aided Design (CAD) to AM opens a completely new means of finding novel ways of processing final objects. By choosing to use kaolin clay without any chemical additions (or improvers) as “a model material,” the ability to produce controlled structures with freedom in design by additive deposition modeling is exposed. Discussions relate to the concomitant control of the process parameters, the kaolin hydration and the complexity of printed structures. The optimization of process parameters (nozzle speed, layer thickness, wall thickness) were defined with the calibration of the material flow. Both windows adjusting water content in dough (%wt) and imposing pressure in the tank of the 3D printer have been defined accordingly. The role of layer impression support was also found to be important. This study credits to use the state-of-the art technique (3D printing) to explore sustainable manufacturing of potteries.
... In addition to providing information about the genesis process of kaolins, the crystallinity of kaolinite particles is of great interest in the exploitation of kaolin ore deposits. Uses of exploited kaolins will depend on their purity and their crystallinity because they will affect physicochemical properties of the materials (Cases et al., 1982;Dubois et al., 1995;Murray, 1999;Ndlovu et al., 2015;Weck et al., 2015;Awad et al., 2017). For example, a good crystallinity (Hinckley Index > 0.7; see "X-Ray Diffraction Crystallinity Indexes: the Hinkley and Liétard Indexes" section) is required for paper manufacture (Murray and Lyons, 1955;Baker and Uren, 1982;Bundy and Ishley, 1991). ...
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Alteration minerals are key objects to understand the geological history of the planetary bodies' surfaces. In this work, I studied the near-infrared spectroscopic properties of opaline silica (e.g. opal) and kaolinite in order to constrain the surface paleoclimatic conditions at the surface of Mars during the past. A preliminary geomorphologic study of opaline silica-bearing deposits on Mars shows four types of deposits: aeolian deposits, hydrothermal deposits, alluvial fan and fan delta deposits, and bedrock. Spectroscopic criteria, distinguishing continental weathering opals and hydrothermal opals, show that aeolian deposits are relicts of hydrothermal deposits. Other deposits are of weathering origin, except hydrothermal deposits that have a spectral signature consistent with low-temperature hydrothermal activity. Near-infrared properties of kaolinite are proxies of its "crystalline degree". Poorly-ordered kaolinites are exclusively of continental weathering origin while well-ordered kaolinites can form either by hydrothermal activity or continental weathering alteration processes.
... It can be topically administered as hemostatic agent, dermatological protector, anti-inflammatory agent and in pelotherapy, or orally as gastrointestinal protector, and antibacterial, antiviral, detoxification or antidiarrheal agent [54,55]. Red kaolin is considerably more absorbent than other kaolin clays and is thus better suited to acne-prone or oily skin [56]. Even though Kaolin clay is not a great absorbent like other clays, especially bentonite clay, it can remove excess sebum from face. ...
Article
The face powder was demanded by many nations in the world in the beginning AD and in Asia white skin was believed to be the sign of aristocratism, membership of the elite, and yet, white color is the pure symbol of the internal beauty and nobility. In addition, some face powders are sold in varying specialty shades to suit different skin needs; for example, a face powder with a greenish tinge will minimize the appearance of redness, while a purple-tinted powder may help the appearance of sallow or yellow skin. There is a legitimate reason to use face powder, and the pharmacopeias prescribe them in the treatment of many skin affections. At all events the proper use of powder is beneficial, it lightly covers and unifies a complexion, hiding the ravages of time, improving even the beautiful face. Face powder comes in different shades to match varying skin tones, and it is a good idea to choose the skin tone that most closely matches the natural skin. This will help the makeup appear more natural; it should be virtually unnoticeable. It may be necessary to use different face powders for summer and winter, as the skin may become tanner in the summer, or drier and in need of extra moisture in the winter. They are of benefit in acne, freckles, sunburn and red nose. Beneath their attractive aspect and odor, face powders should be made by the perfumer to combine the qualities of an elegant cosmetic and therapeutic agent; they must primarily possess adherence, lightness and be transparent; secondly, they should be detergent and delicately absorbent in order to aid the natural functions of the skin, taking up the fatty matters not easily dislodged by water; they should also tend to increase the natural elasticity and regular functions of the skin.
... Kaolinite has excellent technical properties that promote its use as excipients in oral or topical formulations with recognized efficiency to improve bioavailability and controlled drug delivery [53] Montmorillonite Cosmectic ingredient ...
Article
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Clay minerals are often used due to their high adsorption capacity, which has sparked interest in their biological applications to stabilize drugs and pharmaceutical products. This research aims to summarize information about the stability of drugs, cosmetics, dermocosmetics, and pharmaceutical compounds incorporated in the structure of different clay minerals. The databases used to search the articles were Web of Science, Scopus, PubMed, and Science Direct. Photostabilization of these compounds is reviewed and its importance demonstrated. For biological applications, the increase in solubility and bioavailability of clay minerals has proven useful for them as drug carriers. While their natural abundance, low toxicity, and accessible cost have contributed to classical applications of clay minerals, a wide range of interesting new applications may be facilitated, mainly through incorporating different organic molecules. The search for new functional materials is promising to challenge research on clay minerals in biological or biotechnological approaches.
... Biological purification techniques are more economical, eco-friendly, not energy-intensive, and maintains the crystal structure of kaolin clay to a large extent 30,31 but a very slow process for industrial mass production. Beneficiated kaolin can be categorized into two types: hydrous kaolin and calcined kaolin and their uses for specific applications, including paper, ceramics and refractories, plastics, rubber, adhesives, fiberglass, paints, inks, pharmaceuticals and cosmetics, and cracking catalyst or cement industries 32 . ...
Article
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Kaolin (china clay) is a rock material that is very rich in kaolinite. A kaolin ore from Debre Tabor, Ethiopia containing 59.2 wt% SiO 2 , 24.9 wt% Al 2 O 3 , 2.4 wt% Fe 2 O 3, and 8.22 wt% loss on ignition (LOI) was physically beneficiated, chemically leached, and thermally treated for possible industrial use, especially for ceramic membrane fabrication. The leaching experiments were carried out using oxalic acid solutions as leaching reagents for the iron extraction process. The effect of acid concentration, reaction temperature, and contact time on iron leaching was investigated. It was determined that the rate of iron extraction increased with the oxalic acid concentration, leaching temperature, and contact time. A substantial reduction of iron oxide (2.4 to 0.36 wt%) from the raw kaolin was observed at operating conditions of 2.0 M oxalic acid, the temperature of 120 °C, and contact time of 120 min. A maximum kaolin whiteness index of 81.4% was achieved through this leaching process. Finally, the physically beneficiated, chemically leached, and thermally treated kaolin raw material was used to fabricate a low - cost kaolin - based ceramic membrane. After firing at 1100 °C the ceramic membrane was found to have a mass loss of 11.04 ± 0.05%, water absorption of 8.9 ± 0.4%, linear shrinkage of 14.5 ± 0.05%. It was demonstrated to be chemically stable, having less than 3% mass loss in acid solution, and less than 1% mass loss in alkali solution. The newly developed membranes have thus properties comparable to commercial ceramic membranes.
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Formation damage caused by fine migration and straining is a well-documented phenomenon in sandstone reservoirs. Fine migration and the associated permeability decline have been observed in various experimental studies, and this phenomenon has been broadly explained by the analysis of surface forces between fines and sand grains. The Derjaguin–Landau–Verwey–Overbeek (DLVO) theory is a useful tool to help understand and model the fine release, migration, and control phenomena within porous media by quantifying the total interaction energy of the fine–brine–rock (FBR) system. Fine migration is mainly caused by changes in the attractive and repulsive surface forces, which are triggered by mud invasion during drilling activity, the utilization of completion fluid, acidizing treatment, and water injection into the reservoir during secondary and tertiary recovery operations. Increasing pH and decreasing water salinity collectively affect the attractive and repulsive forces and, at a specific value of pH, and critical salt concentration (CSC), the total interaction energy of the FBR system (VT) shifts from negative to positive, indicating the initiation of fine release. Maintaining the system pH, setting the salinity above the CSC, tuning the ionic composition of injected water, and using nanoparticles (NPs) are practical options to control fine migration. DLVO modeling elucidates the total interaction energy between fines and sand grains based on the calculation of surface forces of the system. In this context, zeta potential is an important indicator of an increase or decrease in repulsive forces. Using available data, two correlations have been developed to calculate the zeta potential for sandstone reservoirs in high- and low-salinity environments and validated with experimental values. Based on surface force analysis, the CSC is predicted by the DLVO model; it is in close agreement with the experimental value from the literature. The critical pH value is also estimated for alkaline flooding. Model results confirm that the application of NPs and the presence of divalent ions increase the attractive force and help to mitigate the fine migration problem. Hence, a new insight into the analysis of quantified surface forces is presented in current research work by the practical application of the DLVO theory to model fine migration initiation under the influence of injection water chemistry.
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Six pharmaceutical pastes were prepared using chemically modified kaolin and talc powders. Tests were conducted to determine their structural and chemical characteristics as well as their antimicrobial protection, thus rendering them suitable for cosmetic and pharmaceutical uses. Kaolin and talc were treated chemically via the cation exchange method to load the clay particles with copper and zinc ions, two cations well known for their antimicrobial properties. Mineralogical analyses were conducted by using X-ray diffraction (XRD) before and after the modification, confirming the mineralogical purity of the samples. Scanning electron microscopy was also used in conjunction with energy dispersed spectroscopy (SEM-EDS) to obtain chemical mapping images, revealing the dispersion of the added metals upon the clay minerals surfaces. Moreover, chemical analysis has been performed (XRF) to validate the enrichment of the clays with each metal utilizing the cation exchange capacity. All modified samples showed the expected elevated concentration in copper or zinc in comparison to their unmodified versions. From the X-ray photoelectron spectroscopy (XPS), the chemical state of the samples’ surfaces was investigated, revealing the presence of salt compounds and indicating the oxidation state of adsorbed metals. Finally, the resistance of pastes in microbial growth when challenged with bacteria, molds, and yeasts was assessed. The evaluation is based on the European Pharmacopeia (EP) criteria.
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Hemorrhage is the major hindrance over the wound healing, which triggers microbial infections and might provoke traumatic death. Herein, new hemostatic and antibacterial PVA/Kaolin composite sponges were crosslinked using a freeze-thawing approach and boosted by penicillin–streptomycin (Pen-Strep). Physicochemical characteristics of developed membranes were analyzed adopting Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), a thermal gravimetric analyzer (TGA), and differential scanning calorimetry (DSC). Furthermore, the impacts of kaolin concentrations on porosity, swelling behavior, gel fraction, and degradation of the membranes were investigated. SEM analyses revealed a spongy-like structure of hydrogels associated with high dispersion of kaolin inside PVA matrix. The thermal characteristics of PVA/Kaolin were significantly ameliorated compared to the prime PVA. Moreover, the results exhibited significant variations of swelling performance, surface roughness and pore capacity due to the alterations of kaolin contents. Besides, the adhesive strength ability was manifestly enhanced for PVA-K0.1 sponge. Biomedical evaluations including antibacterial activity, blood clotting index and thrombogenicity of the membranes were studied. The contact of PVA/Kaolin to blood revealed notable augmentation in blood clotting. Furthermore, the incorporation of kaolin into PVA presented mild diminution in antibacterial activities. Moreover, PVA/Kaolin composites illustrated no cellular toxicity towards fibroblast cells. These remarkable features substantiate that the PVA-K0.1 sponge could be applied as a multifunctional wound dressing.
Article
This study aimed at comparative examining of the interactions between conventionally used clay and carbon nanomaterials and human lung adenocarcinoma cells (A549 cells). The following platy and tubular nanomaterials were tested: carbon nanoparticles, i.e. multi-walled carbon nanotubes (MWCNTs) and graphene oxide nanosheets (GO) as well as nanoclays, i.e. halloysite nanotubes (HNTs) and kaolinite nanosheets (Kaol). Nanoparticle physicochemical properties and their internalization into cells were examined using dynamic light scattering as well as atomic force, 3D laser scanning confocal and darkfield hyperspectral microscopies. Biological aspects of the nanomaterial-cell interaction included assessment of cellular toxicity, DNA damage, metabolic activity, and physical parameters of the cells. Regardless of a shape, carbon nanomaterials demonstrated cell surface adsorption, but negligible penetration into cells compared to nanoclays. However, carbon nanomaterials were found to be the most toxic for cells as probed by the MTS assay. They also turned out to be the most genotoxic for cells compared to nanoclays as revealed by the DNA-Comet assay. GO significantly increased the fraction of apoptotic cells and was the most cytotoxic and genotoxic nanomaterial. Comparison of flow cytometry and MTS data indicated that a cytotoxic effect of MWCNTs was not associated with increased cell death, but was rather due to a decrease in cell metabolic activity and/or proliferation. Finally, no significant effect of the shape of the tested nanomaterials on their internalization and cytotoxicity was revealed.
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Kaolinite-rich Cretaceous clay sediment samples from Burgos (Spain) have been analyzed by elemental analylis, X-ray fluorescence, inductively coupled plasma mass spectrometry, X-ray diffraction and different spectroscopic techniques, as Fourier Transform Infrared, ultraviolet-visible and electron paramagnetic resonance. The clay sediment samples mainly contain quartz, muscovite and kaolinite. Different radicals, as A- and B-Centers in kaolinite and organic paramagnetic species, are detected. An illite/kaolinite FTIR band ratio parameter (IKB) is proposed to infer the illite/kaolinite proportion, which can be useful to graphically visualize the iron-substituted Al(III) sites. Studies of the activity as scavengers of DPPH and ABTS radicals show that samples with a larger amount of orthorhombic Fe(III) ions replacing Al(III) ions exhibit a higher antioxidant capacity.
Article
The electrokinetic properties of aqueous suspensions of two kaolins were studied using the acoustophoretic method by measuring the ultrasonic attenuation spectrum in a wide frequency range (1–20 MHz). Then, the zeta potential is calculated according to the size distribution of grains. A high state of crystallinity of the kaolinite platelets strongly influences the amplitude and the variation of zeta potential versus the pH due to a high density of hydroxyl surface groups. It was also shown that specific adsorption occurs mainly with the hydroxyl surface groups of the platelet edges by using strong electrolytes (NaOH and HCl) and also organic molecules (Tiron and sodium salt of citrate). The variation of the surface chemical properties of platelets during the amorphous phase formation after temperature treatment of kaolin powder is also studied. The electrokinetic properties of kaolin suspensions treated between 200 and 800 ◦C successively show an increase in the positive contribution to the zeta potential up to 400 ◦C for the best-crystallized kaolinite and a decrease in the density of surface hydroxyl groups when the sheets delaminate from 400 ◦C for the less-crystallized kaolinite. This study shows that the characterization in aqueous suspension of surface properties of kaolinite complements other studies carried out on powder and therefore it makes it possible to choose kaolin as a raw material according to the intended application
Chapter
Since remote times, some minerals have been used in medicines and cosmetics, alone or in mixtures. The advantage of minerals in pharmaceuticals and cosmetics is the fact that they are natural and that in adequate proportions they are harmless. On the one hand, some minerals are used as active substances or ingredients in pharmaceuticals; examples and their specific roles are reported and discussed. Also, some minerals are used as excipients in pharmaceutical preparations to enhance their organoleptic characteristics, to improve their physicochemical properties, and to facilitate the elaboration, conservation, and liberation of the active ingredient inside the organism. On the other hand, some minerals are used in cosmetics as active ingredients and excipients. At last the chapter provides information about the guidelines relative to elements and minerals that as impurities could be present in pharmaceuticals and cosmetics, as well as about cosmetic microbiology and antimicrobial protection.
Article
In the present work, elegant modification of halloysite (Hal) by citric acid (CA) was realized. The corresponding novel bio-composite (Hal-CA) was then used as drug carrier. To validate this concept, ketoprofen (KET), a known non-steroidal anti-inflammatory agent, was chosen as drug model. KET has low solubility and a short biological half-life, which can cause some limitations in its therapeutic use. In addition, its use is limited due to gastrointestinal side effects. All Hal, Hal-CA, Hal-KET and Hal-CA-KET samples were characterized using several techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), N2 adsorption-desorption, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The release of KET from the prepared formulations was investigated at pH 1 and 6.8 by means of UV–Visible spectroscopy. In addition, kinetics of the release of KET from inclusion complexes were determined by fitting the release profiles to the first order, Korsmeyer–Peppas and Higuchi models. In order to assess these novel bio-composites, anti-inflammatory and anti-nociceptive activities were also evaluated in vivo. Finally, the ulcerogenic activity and the histopathological effects of all formulations were compared to that of pure KET. This work showed the increase of the anti-inflammatory and antinociceptive potentials of KET loaded in Hal-CA, as well as a maximum protection against ulcers. This suggests that Hal-CA can be considered as a new carrier for pharmaceutical formulations.
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This paper presents a facile approach to develop palygorskite (Pal), a fibrous clay mineral, as a delivery system of tea tree oil (TTO) for topical acne therapy. The obtained TTO-Pal composite showed an efficient loading of TTO (27.4%) with a selective accumulation of terpine-4-ol and 1,8-cineole (two major antimicrobial TTO constituents), sustained release of TTO at skin physiological conditions and superior skin sebum (2.2 g/g) absorbability. In vitro toxicological assessments showed that the Pal incorporation strategy significantly reduced the acute contact toxicity of TTO. The antimicrobial results revealed a preferable bacteriostatic effect for the TTO-Pal system towards opportunistic dermal pathogens (Escherichia coli, Staphylococcus aureus and Propionibacterium acnes) over the beneficial bacterium (Staphylococcus epidermis). Moreover, TTO-Pal based formulations exhibited pronounced clinical therapeutic efficacy in treating facial acne by rapidly reducing inflamed lesions, modulating skin sebum overproduction and restoring barrier function. This is the first report of using fibrous clay as a biocompatible nanocarrier system for topical delivery of essential oils in efficient management of facial acne with both in vitro and in vivo evidences, which may open perspectives for fibrous clay-drug delivery system in topical application and expand the high added value development of this mineral resource in the advanced healthcare fields.
Chapter
Biopolymer nanocomposites are the foremost valuable materials among the existing nanocomposites. Biopolymer nanocomposite compounds are biodegradable, eco-friendly and low in cost. Due to these properties, biopolymer nanocomposites can easily replace petroleum-based nanocomposite in various applications. Compared to pure polymer, clay�polymer nanocomposites exhibit favorable physical, chemical, and mechanical properties since they are dispersed at different sizes and contain improved size dispersion and size distribution. There are several biopolymers on earth, but starch is the most abundant. Moreover, its chemical and physical properties make it an important natural polymer.
Article
The vital necessity of effective treatment at damaged tissue or wound site has resulted in emerging tissue engineering and regenerative medicine. Tissue engineering has been introduced as an alternative approach for common available therapeutic strategies in the terms of restoring deformed tissue structure and its functionality via the developing of new bio-scaffold. Designed three-dimensional (3D) scaffolds, alone or in combination with bioactive agents, should be able to stimulate and accelerate the development of engineered tissues and provide proper mechanical support during in-vivo implantation and later regeneration process. To cover it up, a series of new bio-structures with higher mechanical strength were designed through the combination of halloysite nanotubes (HNTs) into 3D bio-polymeric networks. HNTs clay mineral with its unique rod-like structure and distinctive chemical surface features, exhibits excellent biocompatibility and biosafety for doping into regenerative scaffolds to enhance their mechanical stiffness and biological performance. In this paper, the ongoing procedures of bone/cartilage tissue engineering and wound healing strategies focusing on the designing of 3D-HNTs bio-composites and their multi-cellular interactions in-vitro and in-vivo preclinical studies are reviewed. Furthermore, the challenges and prospects of 3D-HNTs and HNTs-based functional bio-devices for regenerative medicine are also discussed.
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Concrete extravagantly used as an anthropogenic building material, unabated in urban development. Globally the cement sector emits about 8% of CO2 (Carbon Dioxide), generated at a ratio of 1MT of CO2 per1MT of cement clinker sintering. Environmental concerns for its degradation through cement. To restrict cement production, natural clay materials and industrial refuges are in to substitute cement part or whole. The present-day hunt is the usage of Metakaolin (MK), a copiously accessible clay in India, as a substituent for cement. The physical, chemical, and mechanical properties of the metakaolin concrete investigated using XRF spectrometer, Scanning Electron Microscopy and universal testing machine following laboratory procedures. The efficiency of MK-concrete at different percentage mixes (0-30%) of ordinary Portland cement replacement at water-cement ratio 0.48 for all the mixes observed. The results suggested that concrete strength reduced significantly during the initial hydration period, particularly at high MK content. The application of up to 15% MK beyond 28 days curing triggers initial setting, time, rises in concrete strength, and increases durability and is also not affected by alkali-silica gel reaction, chloride and Original Research Article Harichandan et al.; CJAST, 41(1): 1-13, 2022; Article no.CJAST.84309 2 sulphate attack. Depending on the age of curing and the MK-concrete durability increases. This work shall reduce the carbon burden of present atmosphere if 15% blended MK cement concrete used.
Article
Natural kaolinite exhibit high affinity for heavy metals while the interaction mechanisms in the presence of heteroatoms remain largely elusive, which are tackled by first principles. In this paper, three common dopants (Mg, Ca, Fe) were employed to construct metal-doped kaolinite(001) (K(001)) surfaces. We found that Mg-doped K(001) was the most stable surface in terms of thermal stability and structural analysis, consistent with the pervasive isomorphic substitution in kaolinite minerals. The interaction of mercury with Mg-doped K(001) surface was investigated in the form of predominant top-site and bridge-site models. The effects of chloride on the interaction were also studied. The results demonstrated that the strongest adsorption occured in the present of dopants and the absence of chloride. The electronic properties revealed a significant charge transfer (up to 1.28 electrons) and chemisorption character at the interfaces when dopants were introduced, which could be ascribed to the overlapping of Hg-5d and Os-2p (surface O) orbitals in the range of −7.5 eV~ +0.5 eV. Additionally, the chloride had a profoundly adverse influence on mercury adsorption due to the upward shift of Hg-6s and Hg-6p orbitals. The studies are beneficial to understand the interaction mechanisms of natural minerals toward environmental pollutants in actual applications.
Article
Clay, or more precisely, certain clay typologies, have been used traditionally by humans for therapeutic, nutritional, and skin-care purposes though they may be responsible for some relatively rare but significant health and skin-care risks. For example, clay particles could adsorb and make available for elimination or excretion any potential toxic elements or toxins being ingested or produced, but they could also adsorb and make available for incorporation, through ingestion or through dermal absorption, toxic elements, e.g. heavy metals. Geophagy has been observed in all parts of the world since Antiquity, reflecting cultural practices, religious beliefs, and physiological needs, be they nutritional (dietary supplementation) or as a remedy for disease. Some clays and clay minerals are employed widely in both the pharmaceutical and cosmetics industries as active compounds/agents and as excipients. In the biomedical field, some clay minerals such as halloysite and montmorillonite are known for their effective role as carriers for the control and sustainable delivery of active drug molecules, and in the biomaterials field some clay minerals are used for scaffold, hydrogel, foam, and film production. Constraints, both chemical and microbiological, on the use of clay-based products for therapeutic and cosmetic topical applications are generally imposed by sanitary regulations, and some solutions are proposed herein to control and reduce such restrictions. Particular emphasis is placed here on peloids and pelotherapy, as well as on manipulated and modified peloids, and specifically on tailored peloids or ‘designed and engineered’ peloids, and their derivatives, bactericidal peloids and ointments. As far as the so-called ‘killer clays’ are concerned, their pre-requisites, mechanisms of action, and disinfection role are also enhanced. Podoconiosis is an environment-related or geochemical disease that occurs in tropical highland areas, and is caused by long-term exposure of bare feet to volcanic, red-clay soil and affects some people, particularly those working in agriculture in some regions of Africa, Asia, and South America.
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A high concentration of calcium ions in water is a problem as it can cause blockages in engine pipes. Adsorption is a relatively cheap and straightforward method that can be used to reduce the calcium ion content in water. Kaolin is a mineral that has a potential as an adsorbent and whose adsorption capacity can be increased by activation. This research studied the adsorption capacity of activated kaolin by hydrochloric acid against Ca ²⁺ ions. Kaolin was chemically activated using 6 M HCl solution for 24 hours. The adsorption contact time in batches was varied with time variations of 30, 90, 150, and 180 minutes. The maximum adsorption capacity of activated kaolin to the Ca ²⁺ was determined by varying the initial concentrations of water samples, namely 4, 7, 10, and 13 mg/L. The concentration of Ca ²⁺ was determined by a titration method using ethylene diamine tetraacetate (EDTA). The results showed that the activation of kaolin with 6 M HCl at the optimum contact time of adsorption, namely 150 minutes, increased the percentage of adsorbed Ca ions to 2 times of that of natural kaolin, from 33.3% to 68.3%. Based on the Langmuir equation, the maximum adsorption capacity of calcium ions by activated kaolin HCl 6 M increased 1.7 times from natural kaolin to 0.346 mg/g.
Article
The aim of this study is to characterize and evaluate the suitability and the quality criteria of two Tunisian peloids taken from the medical thermal stations of Jebel El Oust (JOp) and Korbous (Kp) in northeastern of Tunisia. These peloids are used for the treatment of dermatological pathologies, muscle and bone traumas, and rheumatic pathologies. Their mineralogical and chemical composition was determined respectively by means of X-ray “powder and aggregate” diffraction (XRD) and X-ray fluorescence (XRF) data. Scanning electron microscopy (SEM) and grain size distribution were also carried out for the same purpose. On the other hand, quality, purity, and stability of these thermal muds were evaluated using pharmacotechnical tests (BET surface area, pH, plasticity index, cooling kinetic rate, and CEC). Furthermore, these peloids were compared to those of the Dax thermal station (TERDAX) in France and the natural Tunisian peloids of Kalaa Sghira (Ka). In fact, the mineralogical composition of the Tunisian thermal mud is dominated by illite and kaolinite while the natural and commercial peloids are more heterogeneous as they are made up of various clay minerals, quartz, feldspars, and accessories. In the natural peloids, relatively large quantities of quartz preclude their uncontrolled manipulation. In terms of chemical composition, mainly trace elements, such as those considered to be toxic (Pb and As). The Plomb has been detected only in TERDAX but in much higher concentration (34 ppm) than the necessary limits, while Arsenic was contained in the highest concentration in the TERDAX, Kp, and Ka (112 ppm) samples but not in the K0 or Jebel El Oust samples. Therefore, according to these results and with respect to several parameters traditionally used in pelotherapy, it is possible to conclude that the Tunisian peloids (JOp) are well prepared for an external use whereas with the other peloids, a special attention must be paid to the presence of toxic elements and quartz, which could represent a hindrance for their possible use.
Chapter
The historical evolution of the use of minerals by humans for cosmetic and therapeutic purposes is most probably as old as the human species itself, naturally first applied on an empirical basis, and later moved to a scientific basis initiated with the dawn of scientific revolution, in the Renaissance. Such evolution is classified in this monograph into three periods: the classical antiquity involving ancient civilizations, Mesopotamian, Chinese, Egyptian, Greek, and Roman; the Middle Ages and Renaissance; and the modern and contemporaneous ages. In these periods, the interest for certain minerals as healing natural materials is reported and discussed. The “medicinal terras” of the Greek volcanic islands Lemnos, Chios, Samos, Milos, and Kimolos were particularly famed, as was the case of the “Lemnian terra,” which became known as “terra sigillata” or “terra sealed” supposed to possess supernatural healing properties. On the other hand, certain arsenic-, lead-, and mercury-bearing minerals were soon identified by their poison and lethal properties. From the Renaissance onwards, the First and Second Scientific Revolutions and their particular outcomes in pharmacy and medicine have provided the explanations and justifications for both benefits and risks of minerals/human health interactions.
Article
Kaolinite is an Al-rich phyllosilicate commonly observed on Earth as a product of the chemical weathering of aluminosilicates. It has also been detected on the martian surface by orbital remote sensing observations. If the determination of the geological processes of formation of terrestrial kaolinite (i.e., hydrothermal activity - continental surface weathering - diagenesis) involves the coupling of field observation and multiple laboratory measurements, only geomorphology and associated minerals are generally available to determine their geological origin on Mars. Kaolinite crystallinity depends on many physicochemical parameters reflecting its conditions of crystallization. In order to determine if the near infrared (NIR) spectral signature of kaolinite enables estimation of its crystallinity and further, if this method can be used to identify the geological processes involved in kaolinite formation, we carried out an in-depth analysis of NIR spectra of reference terrestrial kaolinites that formed in various geological contexts. We calculated second and third derivatives for each spectrum to highlight subtle variations in the spectral properties of kaolinite. This allowed the identification of 27 spectral contributions for the 4500 cm-1 and 7000 cm-1 Al-OH-related regions of absorption bands. The position shifts and shape variations of these spectral contributions were intimately linked to variations of crystallinity, which was qualitatively estimated using Hinckley and Liétard XRD (dis)order indices. The results obtained show that the NIR signature of kaolinite is influenced by the stacking disorder of layers that has some influence on the vibrations of the interfoliar and inner Al-OH groups. Our study also confirms that: (1) well-ordered kaolinites are not restricted to hydrothermal deposits; (2) kaolinites from a similar sedimentary or pedogenetic context often display contrasting degrees of crystalline order; (3) poorly ordered kaolinites are more likely to have a sedimentary or pedogenetic origin. Finally, this work highlights that obtaining spectra with sufficient spectral resolution could help to estimate the crystallinity of kaolinite, and in the best cases its geological origin, both on Earth and Mars, especially with in-situ NIR measurements.
Article
To meet the growing energy demands in a low-carbon economy, the development of new materials that improve the efficiency of energy storage and conversion systems is essential. Layered nanoclay offers opportunities in energy storage and conversion applications owing to their great reserves, high surface areas, multi-pore structure and other unique physical and chemical properties. These characteristics provide opportunities and advantages for the application of layered nanoclay in electrochemical energy. In this review, we summarized the structure, classification, modification method and properties of nanoclays, along with discussed their applications as electrodes, electrolytes filler, separators, artificial solid electrolyte interface (SEI) layer in rechargeable batteries and supercapacitors (SCs), and as catalysts in water splitting, CO2 reduction and oxygen reduction. Finally, we concluded the current problems of layered nanoclay in energy storage and conversion, and pointed out the possible future development trend and strategy, which increases their contribution in electrochemical energy applications.
Article
Halloysite nanotubes (HNTs), a traditional mineral Chinese medicine, have been used to stop bleeding for thousands of years. However, the coagulation mechanisms of HNTs and their practical application potential have not been fully elucidated. In this study, HNTs were found to accelerate hemostasis via multiple dependent approaches: (i) absorbing water and concentrating blood due to their super-hydrophilicity and unique tubular nanostructure; (ii) triggering an intrinsic coagulation cascade by negatively charged surface interaction; and (iii) accelerating clot formation by activating and linking with platelets. To solve the difficulty in the application of powder, an HNT-coated polyester fiber dressing was designed by an impregnation method. The HNT coating enables the dressing to resist massive hemorrhaging of the liver and vessels, as well as epidermal bleeding. Moreover, the HNT-coated fiber dressings are not accompanied by burning or adhesion at the wound sites. In summary, this work provides profound insight into HNT hemostasis through the physical and biological interactions between HNTs and blood, which represents a promising strategy for effective prehospital treatment and civilian needs.
Article
Kaolinite particles are geometrically anisometric and electrostatically anisotropic. Until recently, the charge of both basal faces of kaolinite was assumed to be independent of pH, and the isoelectric point (IEP) of the edge surface was thought to occur at pH 4-6. Therefore, kaolinite suspensions were expected to have an edge-face association at low pH. However, recent atomic force microscopy (AFM) studies have shown that the kaolinite alumina basal face and edge surface carry a pH-dependent surface charge with an IEP at pH 5-6 and ∼ 3, respectively. Here, we revisit the modes of particle association in kaolinite suspensions and apply Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to study the rheological implications of surface charges of various kaolinite faces from recent AFM-based studies. Specifically, aging within the linear viscoelastic region, small amplitude oscillatory shear behavior (strain amplitude and frequency response), and critical stress behavior were studied as a function of pH. Kaolinite suspensions (40 wt%) exhibited two-step structure recovery after shear rejuvenation and two-step yielding at pH less than the IEP of the alumina basal face. In addition, the storage modulus (G') and critical stress required to stabilize the flow followed non-monotonic behavior as a function of pH. At low pH, the silica face-alumina face mode of association was expected to be dominant rather than the edge-face microstructure. A peak in the G' vs. pH curve at pH 4.5-5 was correlated with the silica face-alumina face attraction estimated from DLVO theory, which passes through a maximum at approximately the same pH. Based on these observations, we propose a qualitative state diagram for kaolinite suspensions in the pH-concentration space.
Article
Kaolinite clays are the most widespread natural fines attached to the rock surface; they can be mobilised by the flow with further migration in porous spaces, straining in thin pore throats and causing significant decline in the rock permeability. We conducted mathematical and laboratory studies of kaolinite detachment from solid substrates in visualisation cells. The mechanical equilibrium of the attached particles in the creeping flow was described by the torque balance. For uniform particles and substrates, this model presents fines detachment using only two rates that correspond to particles in primary and secondary energy minima, i.e., the attached concentration versus velocity is a piecewise-constant function. To observe this maximum retention function, we saturated a single-channel micromodel visualisation cell with a transparent top with kaolinite particles; it was then subjected to a flow with a piecewise-constant increasing rate. Images of the remaining attached fines were filmed after each rate increase. All the tests exhibit gradual fines detachment. To explain the phenomenon, we assumed a probabilistic distribution of the properties of the particles and the substrate. For two-parametric probability distribution functions, it adds the standard deviations to the list of model parameters. The continuous fines detachment versus velocity was highly matched by the torque balance equation with probabilistically distributed coefficients. The match allowed restoring probabilistic distributions of the selected model parameters from the measured maximum retention function. The sensitivity of the detachment rate to properties follows a decreasing order: semi-major axis, aspect ratio, lever arm ratio, and zeta potential. This work fundamentally advances lab-based mathematical modelling of colloidal detachment from solid surfaces by developing stochastic torque-balance equation, where standard deviations of the model coefficients are tuning / matching parameters along with their mean values. This approach allows determining the probabilistic distributions of the model coefficients from the image processing, and also calculating the attached concentration variation within six standard deviations of each parameter, permitting placing the model parameters in the order of their effect on particle detachment.
Chapter
This chapter is initiated with the record and discussion of the diverse uses of healing clay, both for internal applications involving geophagy and edible clay and for external or topical applications involving the practices called mud therapy and pelotherapy. The etiology and health consequence (benefits, risks, and mechanisms of action) of edible clay are discussed. Distinction is made between geophagy and pica. Distinction is made too between mud and peloid materials, characterized in terms of diversity and typology. One type of peloid, the designed and engineered peloid, is enhanced, since its simple composition, manipulation, and modification allow a better understanding of its medical or cosmetic performance. Peloid’s function, benefits, risks, and mechanisms of action and edible clay mechanisms of action are reported and discussed. Databases of publications on medical and cosmetic pelotherapy are reported. The role of clay minerals in biocomposites, and in controlled drug delivery systems for pharmaceutical and medical applications, the case of halloysite nanotubes, is discussed. The bactericidal activity of some minerals is reported and explained. The chapter ends identifying and discussing diseases whose etiology is attributed to clay such as podoconiosis, Mseleni joint’s disease, Kashin-Beck’s disease, and Keshan’s disease, as well as other adverse effects caused by clay and clay minerals.
Chapter
Clay and clay minerals are ubiquitous constituents of the Earth’s crust, and they are being used by man for therapeutic, cosmetic and many other basic purposes, for instance, in pottery and construction, since prehistoric times. Clay and clay minerals are unique within all other minerals, and as, natural and fine-grained materials they are characterized by singular specific properties such as plasticity and absorption. Also, they are the main constituents of clayey soils and edible clays object of geophagy practices, and of healing mud and peloids used in mud therapy and pelotherapy. This chapter is initiated with relevant information, mainly on clay science, clay and clay minerals’ definition, clay typologies, crystallochemical characteristics and properties of clay minerals’ species as well as clay typology. Clay minerals’ specific properties, such as electric charge (cationic and anionic clay minerals), active sites and functional groups in clay mineral surfaces, basic structural units, planar and non-planar structures and systematic of clay minerals are presented and discussed. The unique properties of certain clays and clay minerals justify their uses for both internal and external applications, in medicines, pharmaceuticals and cosmetics.
Article
Recently, clay minerals and nanoclay-based particles have attracted increasing interests in the preparation of Pickering emulsion owning to their cheap, abundant, natural, nontoxic and biocompatible properties. However, information regarding nanoclay-based Pickering emulsion has not been systematically or comprehensively reported. Herein, this review summarizes the latest advancement in various nanoclays stabilized Pickering emulsions, influential factors of stability and their physicochemical properties, and provides a comprehensive overview of ones for catalytic system, oil spill remediation, encapsulation for active compounds and preparation of functional porous materials applications. In order to boost further research of nanoclay-based Pickering emulsion for practical used in numerous applications, the outlook of existing challenges and opportunities for future development is also presented.
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A decade of research on clays that kill human pathogens, including antibiotic-resistant strains such as methicillin-resistant S. aureus (MRSA), has documented their common characteristics. Worldwide, ∼5% of clays tested to date are antibacterial when hydrated. Most antibacterial clays are from hydrothermally altered volcanics, where volcanogenic fluids produce minerals containing reduced metals. Ferruginous illite-smectite (I-S) is the most common clay mineral, although kaolins dominate some samples. Antibacterial clay mineral assemblages may contain other reduced Fe minerals (e.g. pyrite) that drive production of reactive oxygen species (H 2 O 2 , • OH, • O 2⁻ ) and cause damage to cell membranes and intracellular proteins. Ion exchange can also cause loss of bacterial membrane-bound Ca ²⁺ , Mg ²⁺ and PO 43– . Critically important is the role of clays in buffering the hydration water pH to conditions where Al and Fe are soluble. A nanometric particle size (<200 nm) is characteristic of antibacterial clays and may be a feature that promotes dissolution. Clay interlayers or the lumen of tubular clays may absorb reduced transition metals, protecting them from oxidation. When the clays are mixed with deionized water for medicinal applications, these metals are released and oxidized. Different antibacterial clays exhibit different modes of action. The minerals may be a source of toxins, or by adsorption may deprive bacteria of essential nutrients. In the field, the pH and Eh (oxidation state) of the hydrated clay may help to identify potential antibacterial clays. If the pH is circum-neutral, toxic metals are not soluble. However, at pH < 5 or >9 many metals are soluble and the oxidation of transition metals increases the Eh of the suspension to >400 mV, leading to bacterial oxidation. Understanding the antibacterial mechanism of natural clay may lead to design of new treatments for antibiotic-resistant bacteria, with potential applications in wound dressings, medical implants ( joint replacements, catheters), animal feed stocks, agricultural pathogens, and production of antibacterial building materials. This research exemplifies how ‘geomimicry’ (copying geochemical processes) may open new frontiers in science.
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In this study we focused on antimicrobial nanocomposites based on kaolinite, when two series of nanocomposites were prepared. In the first case, kaolinite (KAO) was used as the carrier for antibacterial drug. Secondly, kaolinite modified with dimethyl sulphoxide (DMSO) was used. In both series, chlorhexidine dihydrochloride (CH) acts as an active antimicrobial component. The resultant samples were characterized by X – ray diffraction (XRD) and infrared spectroscopy (FTIR). The antimicrobial activity of prepared composites against bacteria strains Staphylococcus aureus, Escherichia coli and against yeast Candida albicans were evaluated by finding minimum inhibitory concentration (MIC). It was found that prepared nanocomposites were very effective and they had different effect against bacteria strains and yeast. Important information was that treatment with DMSO had not significant effect on antimicrobial activity. These nanocomposites can be in future used for preparation of drugs for local treatment of oral cavity with long-acting antimicrobial activity.
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'Heat' diarrhea in foals is an onerous but not life-threatening ailment, which indicates that it may be of osmotic origin. This was confirmed by a successful attempt, presented in this paper, to alleviate the severity and duration of foal heat diarrhea with the use of a typical absorbent, kaolin clay, as a feed additive, usually applied in feed production as an anticaking agent. Based on the present results, it can be concluded that treatment of foals maintained on different stud farms with a kaolin paste reduced the duration of heat diarrhea and alleviated its severity (P < 0.05 and P = 0.001). The observed action of kaolin clay, an excellent absorbent, suggests that the so-called heat diarrhea can be caused by disturbances in the intestinal osmotic balance at this specific age of foals. The use of this preparation can reduce the risk of secondary pathological viral or bacterial diarrhea and the requirement for veterinary intervention in foal management. It can also shorten the care period and increase foal well-being, essential for the normal development of a young horse. In addition, prophylactic application of an antidiarrheal preparation based on an industrial by-product, i.e. a cheap component, will reduce the costs of foal care.
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Natural antibacterial clays, when hydrated and applied topically, kill human pathogens including antibiotic resistant strains proliferating worldwide. Only certain clays are bactericidal; those containing soluble reduced metals and expandable clay minerals that absorb cations, providing a capacity for extended metal release and production of toxic hydroxyl radicals. Here we show the critical antibacterial components are soluble Fe2+ and Al3+ that synergistically attack multiple cellular systems in pathogens normally growth-limited by Fe supply. This geochemical process is more effective than metal solutions alone and provides an alternative antibacterial strategy to traditional antibiotics. Advanced bioimaging methods and genetic show that Al3+ misfolds cell membrane proteins, while Fe2+ evokes membrane oxidation and enters the cytoplasm inflicting hydroxyl radical attack on intracellular proteins and DNA. The lethal reaction precipitates Fe3+-oxides as biomolecular damage proceeds. Discovery of this bactericidal mechanism demonstrated by natural clays should guide designs of new mineral-based antibacterial agents.
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Kaolin is a mineral composite derived from clay soil. It has been used for long time in medicine as an antidiarrhea. Antidiarrheal function of kaolin comes from its work locally at intestine as a strong adsorbent. Some contaminants which cause diarrhea in intestine will be adsorbed by kaolin and wasted with faeces. Adsorption capacity of adsorbent agent is influenced by surface properties and its porosity. Improving surface adsorption characteristics of the adsorbent agent will increase its adsorption capacity. Several efforts to increase adsorption capacity of adsorbent have been carried out such as structure modification of matter by chemical or physical ways. Chemical modification uses a complicated method than physical ways. Physical modification can be done by reducing particle matter or with high temperature heating like calcination. Reducing particle needs more time and energy, but with calcination structure modification is formed spontaneously and rapidly with a simple way. Calcination is an endothermic process with high temperature heating, but still under its melting point. With calcinations, the structure will thermally deformed with changes in mineral composite formation. In this research, the effect of calcination temperature variations on kaolin's deformation and adsorption capacity has been studied. Deformation of mineral composite was studied by X-Ray diffractogram from Powder X-Ray Diffractometer, and the adsorption capacity was analyzed by measuring number of Pb being adsorbed by using Atomic Absorption Spectroscopy. The result showed that at the 400°C deformation did not occur yet, but at 600° and 800°C temperature the deformation began. The adsorption capacity of Pb at 400°C raised by 0.377%, but on the contrary, at 600° and 800°C decreased significantly by 7.198% and 20.761%, respectively. Conclusion from those data indicated kaolin has raised adsorption capacity at 400°C, getting more heated the deformation of kaolin occured with lower adsorption capacity.
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The desirable physical and physiochemical properties of clay minerals have led them to play a substantial role in pharmaceutical formulations. Clay minerals like kaolin, smectite and palygorskite-sepiolite are among the world's most valuable industrial minerals and of considerable importance. The elemental features of clay minerals which caused them to be used in pharmaceutical formulations are high specific area, sorption capacity, favorable rheological properties, chemical inertness, swelling capacity, reactivity to acids and inconsiderable toxicity. Of course, these are highly cost effectual. This special report on clay minerals provides a bird's eye view of the chemical composition and structure of these minerals and their influence on the release properties of active medicinal agents. Endeavor has been made to rope in myriad applications depicting the wide acceptability of these clay minerals.
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The sixth volume in the six-volume Handbook of Pharmaceutical Manufacturing Formulations, this book covers the sterile products, which include formulations of injections, ophthalmic products and other products labeled as sterile, from publicly available but widely dispersed information from FDA New Drug Applications (NDA), patent applications, and other sources of generic and proprietary formulations. Each entry begins with a fully validated scaleable manufacturing formula and a summary of manufacturing process. The book provides a detailed discussion on the difficulties encountered in formulating and manufacturing sterile products, the common elements of formulation. The section on regulatory and manufacturing guidance deals with the topics inspection of sterile products manufacturing facilities, new drug application for sterilized products, in addition to providing quick tips on resolving the common problems in formulating sterile products as well as the scope of details included in the series for all dosage forms.
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The largest category of pharmaceutical formulations, comprising almost two-thirds of all dosage forms, compressed solids present some of the greatest challenges to formulation scientists. The first volume, Compressed Solid Products, tackles these challenges head on. Highlights from Compressed Solid Products, Volume One include: Formulations for more than 200 of the most widely used drugs for all types of release profiles, offering formulators a rare opportunity to start with an optimal composition. The essentials of what you need to be aware of when establishing a manufacturing process based on the formulations presented. Identification and inclusion of the most popular prescription products, a critical list for the selection of products.
Article
Enteric viruses such as Norwalk virus (NV) are important agents of waterborne disease from faecally contaminated groundwater. Viruses are more resistant to inactivation than most enteric bacteria and they may not be removed efficiently during land application. Adsorption is one of the major factors in viral removal and persistence in soils. The adsorption of NV by soils suspended in wastewater has not been determined. Therefore, we determined the adsorption of NV to six soils (Cecil clay-loam, Corolla sand, Georgia Kaolinite (clay), Wyoming Bentonite (clay), Ponzer organic muck and Flushing Meadows sand-loam) suspended in treated wastewater and compared it to that of poliovirus 1 (PV1) (strongly adsorbed) and MS2 (weakly adsorbed). NV is shown to be less sorptive than PV1 and more sorptive than MS2. Furthermore, relative virus adsorption among soils was similar for all three enteric viruses with viruses most adsorbed by clays and least adsorbed by sand and organic soils.
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Agrochemical products and adjuvants are of vital importance in agriculture, to protect food and fibre crops from weeds, insect pests and diseases, in order to feed and clothe the growing world population. In recent years there have been increasing pressures to produce agrochemical formulations which have a lower environmental impact and are safer in use. Enormous changes have taken place in the chemistry and technology of agrochemicals over the last twenty years or so and this book provides a timely review of the most important area of technology in the development of new products. This book covers issues around international product quality and safety standards and describes the current and likely future trends which will carry the industry forward into the next millennium. It brings together well known international experts with many years of practical experience from agrochemical companies, consultancies, academic institutions and regulatory bodies. Chemists and technologists involved in developing new or improved agrochemical formulations will find this book an essential reference in the course of their work. The book will also be of interest to those working in research and development departments of raw material suppliers, as a concise review of this important field.
Article
This work aimed to evaluate by first time the suitability of the Egyptian Abu Zenima (Sinai Peninsula) kaolins to be used in pharmaceutical and cosmetic applications. Sixty five kaolin samples were collected from six stratigraphic sections: Wadi Khaboba, Gabal Hazbar and Wadi Abu Natash sections, belonging to the Abu Thora Formation (Carboniferous age), and Gabal El Dehessa, Gabal Farsh El Ghozlan and Wadi Budra sections, belonging to the Malha Formation (Lower Cretaceous), and characterized by mean of X-ray diffraction and fluorescence, electron microscopy, spectrophotometry and rheometry. Most of the samples were dominated by kaolinite, and half of the samples contained > 75% of this mineral, reaching up to 96%. Quartz was the main impurity, with very variables quantities; it was always present except in some parts of the Wadi Abu Natash and Wadi Budra sections. Mica, anatase and hematite were frequently present, but they normally did not exceed 10%. Other detected impurities were carbonates (calcite, dolomite, ankerite), sulfates (gypsum, alunite), smectite, feldspars, magnetite, pyrite, halite and heulandite, but in lesser amounts and only in some samples. Carboniferous kaolinites exhibited a high crystallinity (Hinckley Index > 1), while most of Cretaceous kaolinites were medium to poorly crystallized (Hinckley Index normally < 1). CIELAB colorimetric parameters put into evidence the general grayish color of the samples, some of which showing light tints of redness and yellowness in correlation with their iron content. The rheological characterization of the 31 purest kaolin samples revealed that their dispersion exhibited similar and good pseudoplastic flow behavior at 50% W/W solid concentrations. The apparent viscosity and yield stress values of Carboniferous samples showed a widest range of variations when compared to Cretaceous ones. The observed variations were interpreted to be correlated with both, the kaolinite content as well as microtexture and the dimensions of kaolinite particles. With these premises, some of the studied kaolins are considered to have a very high economic potential, once the detected impurities are removed easily by the appropriate process, and then suitable for pharmaceutical and cosmetic purposes. Even if there were zones rich in kaolinite in all the studied sections, the highest quality for the target purposes is found at the lower part of the Wadi Abu Natash section, where quartz was absent and include the samples with the highest viscosities.
Article
Focus here is placed on the pharmaceutical and biomedical applications of novel clay-drug hybrid materials categorized by methods of administration. Clay minerals have been used for many years as pharmaceutical and medicinal ingredients for therapeutic purposes. A number of studies have attempted to explore clay-drug hybrid materials for biomedical applications with desired functions, such as sustained release, increased solubility, enhanced adsorption, mucoadhesion, biocompatibility, targeting, etc. The present review attempts not only to summarize the state-of-the-art of clay-drug hybrid materials and their advantages, depending on the methods of administration, but also to deal with challenges and future perspectives of clay mineral-based hybrids for biomedical applications.
Chapter
The development of drug delivery systems always goes hand-in-hand with the advancement of material science. The novel synthetic or natural functional materials provide opportunities to design optimal drug delivery systems. Emerging trends in the design and development of drug products indicate ever greater need for characterization of excipients and in-depth understanding of their roles in drug delivery applications. This book presents an integrated approach to the characterization and application of excipients. This chapter provides an overview of excipient applications in formulation design and drug delivery with focus on stability implications of drug-excipient interactions, impact of excipients on drug release and bioavailability, the factors that weigh into excipient selection and formulation design, including excipient functionality.
Article
Chlorhexidine acetate-loaded silver-kaolinite (CA-Ag-Kaol) was prepared and characterised, and its application as an antibacterial agent was studied. CA-Ag-Kaol was prepared by the adsorption of chlorhexidine acetate (CA) (0.5 mmol/L) on Ag (50% of the Cation Exchange Capacity (CEC) of kaolinite) on kaolinite. Kaolinite (Kaol), silver-kaolinite (Ag-Kaol), CA-modified kaolinite (CA-Kaol) and CA-Ag-Kaol were characterised by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field-emission scanning-electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, zeta potential analysis and dispersion behavior measurements. The modification of kaolinite with cationic silver and chlorhexidine ions did not change the structure of kaolinite, and the characterization of the kaolinite samples revealed the successful loading of cationic silver and chlorhexidine ions on the kaolinite. The antibacterial assay of the samples was carried out against Escherichia coli ATCC 11229, Pseudomonas aeruginosa ATCC 15442, Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 29212 using the disc diffusion technique (DDT) and the minimum inhibition concentration (MIC) technique. Based on the antibacterial assay, CA-Ag-Kaol showed better antibacterial activity than Ag-Kaol and CA-Kaol, and it performed well in both distilled water and a 0.9% saline solution. Gram-positive bacteria were more susceptible to the antibacterial behavior of Ca-Ag-Kaol than Gram-negative bacteria. In conclusion, silver-kaolinite that has been loaded with chlorhexidine acetate can be used as an effective antibacterial agent because of its high antibacterial activity against wide spectrum of bacteria in solutions containing electrolytes (saline solution).
Book
Written by experts from academia, industry and regulatory agencies, Discusses the development of stable pharmaceutical suspensions Suspension dosage form is a preferred and widely accepted dosage forms for insoluble or poorly soluble drugs for various therapeutic applications. The suspension dosage form has long been used for insoluble and poorly soluble drugs for making oral, topical and parenteral products. Pharmaceutical Suspensions, From Formulation Development to Manufacturing provides the reader with a broad overview of suspension drug product technology. Individual chapters in this book focus on suspension formulation principles, excipients, analysis, pharmaceutical development, preclinical, clinical and regulatory aspects, as well as the emerging technology of nanosuspensions as nanomedicine. Various chapters in the book are written by authors from academia, regulatory agencies and industries who are experts in their respective fields. The book includes over 600 bibliographic citations, numerous tables and illustrations. Pharmaceutical Suspensions is the only volume to date that systematically follows the suspension dosage development approach used widely in the pharmaceutical industries starting with pre-formulation/formulation development, pre-clinical evaluation and critical characterization method development, continuing to clinical trial essentials and ending with technology transfer essentials and regulatory filing guidance. Pharmaceutical Suspensions, From Formulation Development to Manufacturing provides a useful resource for pharmaceutical scientists, process scientists/engineers involved in the areas of research and development of pharmaceutical suspension dosage forms as well as for advanced pharmacy undergraduate and graduate students who want in-depth knowledge of suspension dosage form.
Article
Sittigs Handbook of Pesticides and Agricultural Chemicals is specifically designed for use by those engaged in the agricultural and food processing industries, both vital to our nations health and economy. People in every phase of food production, from the farm to the fork, will find a wealth of material here. It will also be of interest to professionals in the pharmaceutical, cosmetics, and personal care industries who use agricultural products as ingredients. It provides crop, chemical, regulatory, health and safety information on nearly 800 pesticides, fertilizers, and other agricultural chemicals. These chemicals are organized withg unique identifiers so that all who may have contact with or interest in them can find critical information quickly.
Article
An oral solid dosage form should ideally disperse into the primary particles from which it was prepared. Tablets and capsules which need rapid disintegration, the inclusion of the right disintegrant is a prerequisite for optimal bioavailability. Superdisintegrants are used to improve the efficacy of solid dosage forms. This is achieved by decreasing the disintegration time which in turn enhances drug dissolution rate. Disintegrants are substances or mixture of substances added the drug formulation that facilitates the breakup or disintegration of tablet or capsule content into smaller particles that dissolve more rapidly than in the absence of disintegrants. Superdisintegrants are generally used at a low level in the solid dosage form, typically 1- 10 % by weight relative to the total weight of the dosage unit. The present study comprises the various kinds of superdisintegrants which are being used in the formulation to provide the safer, effective drug delivery with patient's compliance.
Article
This manuscript reports on the effects of natural Fe-halloysite matrices on infiltration and migration of neutrophils (polymorphonuclear (PMN) leukocytes), which, after the skin, constitute the primary protection of organisms against pathogens. Speciation of mineral Fe was quantified before and after treatment with citrate-bicarbonate-dithionite (CBD). Infiltration and migration of inflammatory and immune effector cells, and cell viability were quantified using the 12- O-tetradecanoylphorbol-13-acetate (TPA) and myeloperoxidase (MPO) enzymatic activity methods, and the Griess assay. Halloysite was collected ~. 2 km from Opotiki, Bay of Plenty, New Zealand. HRSEM images confirmed typical morphological features proper of spheroidal Hal (S-Hal). Mössbauer spectroscopy of S-Hal confirmed the presence of Fe, octahedrally coordinated in the form of substituted Fe(III), magnetically ordered goethite or ferrihydrite. HRTEM images showed the presence of small-size domains of Fe (~. 3-nm) predominantly in the form of ferrihydrite. EPR analyses of S-Hal (0-5000. ppm) before and after reacting with desferrioxamine-B confirmed the fast release of Fe from the nanodomains of ferrihydrite. Early inhibition of edema by S-Hal doubled that by CBD treated Hal (t-S-Hal), explained because labile Fe (2- L-ferrihydrite) enhanced the 4-h anti-inflammatory response. On the other hand, prolonged inhibition of edema by S-Hal and t-S-Hal compared, consistent with the release of Fe from the Hal structure. The presence of S-Hal or t-S-Hal related to the inhibition of MPO content. After 4 h, the inhibition of MPO content by S-Hal or t-S-Hal compared to that by commercial indomethacin (ca. 80%). S-Hal or t-S-Hal showed high inhibition of MPO contents shortly after exposure, but decreased sharply afterwards. On the other hand, tubular Hal (T-Hal) caused an increasing inhibition of MPO with time, explained because clay structure restricted the kinetics and mechanism of MPO inhibition. Evidenced showed that the release of mineral Fe related to infiltration and migration of inflammatory and immune effector cells, expanding the knowledge that metal ions affect inflammatory responses. Finally, dose-response experiments confirmed that the inhibition of edema and cell viability were surface-mediated. Natural clay reservoirs are complex in composition, therefore identifying the molecular mechanism(s) regulating cell migration and infiltration becomes necessary prior to recommending their use for healing purposes.
Chapter
Humans have utilized clay minerals since prehistoric times. With advances in nanotechnology and the increased need for sustainable development, naturally occurring clay minerals and their man-made variants provide hope for further improving the quality of human life. However, high levels or inappropriate exposure of clay minerals to the environment and humans could lead to undesirable effects. This chapter reviews progress made over the last 10 years especially in understanding the mechanisms underlying novel applications of clay minerals in many areas, the limitations and future trend of their applications, and the impact of polymer. -. clay composites on developments in society.
Article
Formulation development is the most emerging and upcoming face of pharmaceutical technology in the current era. It is contemporarily capturing the market leaps and bounds with recent trends and developments with its innovative techniques. The day-to-day advancements in the research have provided an edge to this brilliant branch of pharmaceutical sector for not only uplifting the pharmacy profession but also to conquer the diseased state for nurturing the health and humanity. The fluid-bed technology or air-suspension process is the potential tool to develop newer trends and implications in the sector of formulation development with maximum therapeutic efficacy. The technology is used for granulation/agglomeration, layering and coating of a wide range of particle size. In addition; the technique can be used for the drying process as well. The three patterns of the fluid-bed processes could be characterized by the position/location of the spray nozzle i.e. top spray, bottom spray or tangential spray. This article reviews the three techniques with some innovative fluid bed pelletizing technologies like CPS™, MicroPx™, ProCell™ and discusses their applications, advantages and limitations. These advanced pelletizing technologies are recentely added to complement the actual capabilities of standard fluid bed processing for development of various dosage forms of “Multiple Unit Particulate Systems” (MUPS) with better therapeutic efficacy and economic benefits.
Article
Phyllosilicates, and among them clay minerals, are of great interest not only for the scientific community but also for their potential applications in many novel and advanced areas. However, the correct application of these minerals requires a thorough knowledge of their crystal chemical properties. This chapter provides crystal chemical and structural details related to phyllosilicates and describes the fundamental features leading to their different behaviour in different natural or technical processes, as also detailed in other chapters of this book. Phyllosilicates, described in this chapter, are minerals of the (i) kaolin-serpentine group (e.g. kaolinite, dickite, nacrite, halloysite, hisingerite, lizardite, antigorite, chrysotile, amesite, carlosturanite, greenalite); (ii) talc and pyrophyllite group (e.g. pyrophyllite, ferripyrophyllite); (iii) mica group, with particular focus to illite; (iv) smectite group (e.g. montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite); (v) vermiculite group; (vi) chlorite group; (vii) some 2:1 layer silicates involving a discontinuous octahedral sheet and a modulated tetrahedral sheet such as kalifersite, palygorskite and sepiolite; (viii) allophane and imogolite and (ix) mixed layer structures with particular focus on illite-smectite.
Article
Bentonites, naturally occurring clays, are produced industrially because of their adsorbent capacity but little is known about their effects on human health. This manuscript reports on the anti-inflammatory activity of bentonites. Bentonites collected from India (Bent-India), Hungary (Bent-Hungary), Argentina (Bent-Argentina), and Indonesia (Bent-Indonesia) were studied. All four bentonites were tested for anti-inflammatory activity using the mouse ear edema and the 12-O-tetradecanoylphorbol-13-acetate (TPA) method. Bentonites inhibited edema after 4. h (EI %), regardless of composition. A direct comparison between EI and surface area values showed that Bent-Argentina was four times more active than the other bentonites, with infiltration preferred in the former case. We attributed the inhibition of edema by bentonites to clay swelling, causing physical occlusion thereby limiting the movement of leukocyte cells towards the inflammation site. Expandability over changes in mineral composition underpinned inhibition of edema by bentonites, while evidence lacked to support chemical-transfer mechanism(s).
Article
The knowledge of the properties of colloidal dispersions is fundamental for designing and optimizing the usage of clays and clay minerals. The colloidal behaviour of these dispersions is very complex due to the anisometric (and often irregular) particle shape, the anisometric and pH-dependent charge distribution, the variable particle dimensions as a consequence of swelling, delamination and exfoliation, and the ion-exchange properties. Therefore, this chapter gives information on the structure, charge distribution, structure of the hydrates, diffuse ionic layer, and the interactions between the colloidal clay mineral particles (electrostatic, van der Waals, ion correlation, steric stabilization). A large section refers to the coagulation of clay mineral dispersions by salts, the influence of organic compounds, and the destabilization (flocculation by bridging or charge neutralization) or stabilization by polymers (by recharging or steric stabilization). In a further section is described the aggregation of clay mineral particles leading to different types of sediments (decisively determining sealing, plastering, stirring, filtration processes, plasticity) or resulting in gel formation, often with thixotropic properties. Also mentioned is the preparation of colloidal metal (hydr)oxides and sulphides within the network of clay mineral particles or even between the clay mineral layers.