No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Synthesis, functionalization, and environmental application of silica-based mesoporous materials of the M41S and SBA-n families: A review
Abstract
The functionalized silica-based mesoporous molecular sieves are widely used successfully in various applications, mainly due to their interesting and unique textural and structural features, which allow their use in the most different scientific areas, such as catalysis, adsorption, separation of target molecules, drug delivery devices, chemosensors, biosensors, so on. In this review, we report the state of the art of recent advancements on the modified, inspired, and architectured M41S- and SBA-n-based mesoporous arrays syntheses and its strategic use in the environmental approaches, mainly due to the great interest and need of the scientific community to obtain functionalized arrays with multiple features. In view of the different approaches that have been extensively explored for the functionalization of nano-architectured arrays presented in the literature, it is possible to state that the strategies of modification of the M41S- and SBA-n-based mesoporous arrays can enhance the adsorptive, catalytic, and separation properties of the functionalized mesoporous architectures. Thus, evidencing that these multifunctional materials synergistically modified, with different pore geometries and architectures, can be widely used in the environmental remediation area, aiming to minimize environmental impacts, improve quality of life, and avoid the generation of waste, aiming at an increasingly green, clean, and sustainable footprint in the synthesis and application processes of these multifunctional materials.
... On the other hand, mesostructured silica materials have aroused great interest within the scientific community and are used in various industrial applications, including catalysis, separation processes and the control of environmental pollution [23]. These materials exhibit a highly ordered mesoporous structure (with pore diameters ranging from 2 to 50 nm according to IUPAC), resulting in well-defined pore sizes, a large pore volume, a high surface area and easily modifiable pores [23][24][25]. ...
... On the other hand, mesostructured silica materials have aroused great interest within the scientific community and are used in various industrial applications, including catalysis, separation processes and the control of environmental pollution [23]. These materials exhibit a highly ordered mesoporous structure (with pore diameters ranging from 2 to 50 nm according to IUPAC), resulting in well-defined pore sizes, a large pore volume, a high surface area and easily modifiable pores [23][24][25]. A highly studied mesoporous material is SBA-15-type silica (Santa Barbara Amorphous number 15), developed by Zhao et al. [26], which has a hexagonal structure. ...
... A highly studied mesoporous material is SBA-15-type silica (Santa Barbara Amorphous number 15), developed by Zhao et al. [26], which has a hexagonal structure. This material has great hydrothermal stability due to its thicker, amorphous walls and relatively large pores [23]. Its synthesis is simple; a source of silicon is needed, generally tetraethylorthosilicate (TEOS), a commercial triblock copolymer called Pluronic 123 with amphiphilic character (hydrophilic zone and another hydrophobic zone) and ordering properties, which is used as a director of the structure and acidic conditions with HCl. ...
This work focuses on the development of a hybrid material based on SBA-15 silica with a molecularly imprinted polymer (MIP), using spiramycin (SPI) as a template, for use as sorbent in solid-phase extraction (SPE). Characterization techniques such as nitrogen gas adsorption–desorption isotherms, infrared spectroscopy and scanning electron microscopy confirmed the structure and properties of the SBA-15@MIP-SPI material. SPE conditions using SBA-15@MIP-SPI as sorbent were optimized, which allowed us to demonstrate the high selectivity and adsorption capacity of SPI on the synthesized material. The best conditions were 50 mg of sorbent, loading with 1 mL of standard solution or sample of cow milk previously extracted in acetonitrile and eluting with 3 mL of methanol with 1% acetic acid. After the optimization process, the material demonstrated recovery percentages of 81 ± 3% in SPI standard solutions and showed its potential in cow milk samples (71 ± 6%). The novelty of the research consists of the combination of MIPs with SBA-15, which could offer important advantages in terms of specific surface area and porous structure, thus improving performance and reducing the amount of sorbent compared to other traditional methods.
... The easiness of tuning structural properties by simple altering the reaction conditions has been claimed as one of the major advantages of porous materials when envisioning specific applications because of the possibility of rationally control the physicochemical features. [1][2][3] Among porous materials, silica-based ones have caught the attention due to the easiness of attaching functional groups at either the external and internal surface porous. [2][3][4] This versatility has allowed the use of silica-based materials as adsorbents, 3 biomolecules immobilization, 5,6 gas storage, 7 sensors, 8 drug release, 2,5,9 and support for catalysts. ...
... [1][2][3] Among porous materials, silica-based ones have caught the attention due to the easiness of attaching functional groups at either the external and internal surface porous. [2][3][4] This versatility has allowed the use of silica-based materials as adsorbents, 3 biomolecules immobilization, 5,6 gas storage, 7 sensors, 8 drug release, 2,5,9 and support for catalysts. [10][11][12] In heterogeneous catalysis, it is crucial to have catalyst supports that provide mechanical resistance, high surface area, and thermal stability. ...
... [1][2][3] Among porous materials, silica-based ones have caught the attention due to the easiness of attaching functional groups at either the external and internal surface porous. [2][3][4] This versatility has allowed the use of silica-based materials as adsorbents, 3 biomolecules immobilization, 5,6 gas storage, 7 sensors, 8 drug release, 2,5,9 and support for catalysts. [10][11][12] In heterogeneous catalysis, it is crucial to have catalyst supports that provide mechanical resistance, high surface area, and thermal stability. ...
... This is attributed to their high surface areas and well-defined pore sizes. Additionally, these materials can interact with ions, atoms, and nanoparticles [30]. ...
... M41S members are toxicologically safe, chemically and thermally stable, mechanically strong, water-soluble, and have high active site concentrations on their surfaces [30,32]. Another characteristic of such materials is the presence of silanol (Si-OH) groups on the surface [33]. ...
... The functionalization broadens the applications of these materials in various fields [36]. The functionalization of these materials is mainly facilitated by the high reactivity and concentration of silanol groups on the surfaces of mesoporous material [30]. [38]. ...
Silica-based mesoporous materials are a class of porous materials with unique characteristics such as ordered pore structure, large surface area, and large pore volume. This review covers the different types of porous material (zeolite and mesoporous) and the physical properties of mesoporous materials that make them valuable in industry. Mesoporous materials can be divided into two groups: silica-based mesoporous materials and non-silica-based mesoporous materials. The most well-known family of silica-based mesoporous materials is the Mesoporous Molecular Sieves family, which attracts attention because of its beneficial properties. The family includes three members that are differentiated based on their pore arrangement. In this review, the major applications of the Mobil Mesoporous Molecular Sieves family, such as catalysts, adsorbents, and drug delivery agents, have been surveyed. Furthermore, the synthesis of the Mesoporous Molecular Sieves materials, the silica sources, the importance of templates, and the mechanisms of the synthesis are discussed herein. Members of this material family are characterized by many physicochemical properties that are closely related to their high silica content, crystalline structure, and pore arrangement. Commonly, the members of this family have large surface areas, high pore volumes, small pore sizes, and narrow and uniform particle size distributions. These properties enable numerous industrial applications and opportunities for scientific studies to further develop existing materials or manufacture new ones.
... Santa Barbara Amorphous-15 (SBA-15) is a mesoporous silica (MS) sieve known for its superior features (i.e., large specific surface area, high stability, high capacity adsorption, etc.) and various applications (i. e., water treatment, CO 2 hydrogenation, dying, drug removal, etc.) [5][6][7]. The adsorptive properties of the SBA-15 are required to be improved via modification [7]. ...
... e., water treatment, CO 2 hydrogenation, dying, drug removal, etc.) [5][6][7]. The adsorptive properties of the SBA-15 are required to be improved via modification [7]. ...
... NH 2 -functionalized mesoporous hydroxylated SBA-15 (NH 2 -H-SBA-15) was produced to adsorb uranium. The stable adsorption characteristics in a wider pH range (6)(7)(8) were due to the existence of amino groups which had better adaptability in alkaline and weakly acidic environments. The isothermal and adsorption kinetic models were well-fitted to Langmuir and pseudo-second-order models, respectively, indicating that uranium adsorption belongs to chemical adsorption. ...
In this study, a Melamine-functionalized mesoporous silica-SBA-15 (Melamine-MS-SBA-15) adsorbent was synthesized to remove Cr(VI) from wastewater. The mesoporous silica-SBA-15 adsorbent was first synthesized using the hydrothermal method and post-synthesis under toluene reflux. Then, 3-aminopropyl trimethoxy silane was added to the adsorbent surface and it was further modified by melamine to obtain the final product. SBA-15 well-performed after Melamine functionalization against the Cr(VI) removal due to the conversion of physisorption to chemisorption adsorption. The adsorption of Cr(VI) using the Melamine-MS-SBA-15 was studied. XRD, BET, SEM, FTIR, TGA, and zeta potential analyses were used to characterize the adsorbent. Parameters affecting adsorption including pH (3–9), initial concentration (20–200 ppm), contact time (1–24 h), adsorbent dose (1.5–15 mg L-1), and temperature (18–30 ◦C). Optimal results were pH =3, an initial concentration of 20 ppm, an adsorbent dose of 4 mg L-1, a contact time of 6 h, and a temperature of 18◦C. The results of isotherm and kinetics model studies were consistent with Temkin and pseudo-second-order models, respectively. The thermodynamics parameters confirmed the spontaneous reaction.
Experimental results showed that functionalization of the adsorbent surface of MS-SBA-15 with melamine increased the adsorption efficiency and adsorption capacity.
The highest adsorption capacity for Cr(VI) was about 50
mg/g. The maximum adsorption efficiency for solutions containing Cr(VI) was about 84%. Increasing the adsorption concentration in a fixed value of the heavy metal concentration increased the adsorption capacity and increasing the heavy metal concentration increased the adsorption capacity.
... In addition, the formation of tunnels and channels in the structure determines the presence of silanol groups (≡Si-OH) at the silicate's fibers exterior surface, which can be functionalized to introduce new properties. Therefore, numerous organic and inorganic species, including polymers [8] and oxides [9], can easily access these free Si-OH silanol groups, enabling the development of hybrid compounds, which have implications for a wide range of industrial applications [10]. Given this, the surface modification of clays with metal oxides, such as FeO, Al 2 O 3 [11], MnOx [12], or ZnO [10], can significantly improve their performance in a specific application. ...
... Isothermal adsorption models were employed to determine the maximum adsorption capacity of the adsorbents for ciprofloxacin. Experiments were conducted using different initial ciprofloxacin concentrations (6,8,10, and 14 mg/L) at room temperature and a contact time of 120 min. The equilibrium adsorption data were fitted to the Langmuir [19] (Equation (5)), Freundlich [14] (Equation (6)), and Temkin [20] (Equation (7)) models. ...
Citation: Campos, V.N.S.; Santos, J.D.J.P.; Araújo, R.J.P.; Lopes, P.H.S.; Garcia, M.A.S.; Rojas, A.; Teixeira, M.M.; Bezerra, C.W.B.; Alcântara, A.C.S. High Performance of Ciprofloxacin Removal Using Heterostructure Material Based on the Combination of CeO 2 and Palygorskite Fibrous Clay. Minerals 2024, 14, 792. https://doi. Abstract: Ciprofloxacin, a second-generation fluoroquinolone, is widely used in human and veterinary medicine. However, it is known for its environmental persistence and ability to promote bacterial resistance, causing genotoxic impacts and chronic toxicity in various aquatic life forms. Adsorption is an effective technique for water treatment, removing multiple organic molecules, even in minimal concentrations. Hybrid materials based on fibrous clay minerals, such as palygorskite, are promising for environmental remediation, significantly when modified with oxides to improve their adsorption properties. This work prepared and characterized a CeO 2 /palygorskite hybrid material using various physicochemical techniques (XRD, FTIR, BET, SEM), which indicated the formation of the heterostructure material with interesting textural properties. This CeO 2 /palygorskite was evaluated as an adsorbent of the antibiotic drug ciprofloxacin. The influence of pH (3, 7, and 9) and ciprofloxacin concentration (6, 8, 10, and 14 ppm) on adsorption were studied, using pseudo-first-and pseudo-second-order kinetic models. The pseudo-second-order model showed the best fit (R 2 > 0.99) and the lowest squared error (SSE), indicating chemisorption. The Langmuir, Freundlich, and Temkin isotherms were applied to the experimental data, where the Langmuir model had the best fit, indicating monolayer adsorption with a maximum capacity of 15 mg·g −1. Post-adsorption characterization by FTIR confirmed the structural stability of the material, highlighting its promising application in environmental remediation due to its high concentration of adsorbents.
... Traditionally, three mesophases, collectively known as MCM-41 adsorbents, were synthesized and are described as mesoporous (according to the IUPAC nomenclature) due to their pore diameters ranging between 2 and 50 nm [2]. The MCM-41 family presents three mesoporous materials, silicates, and aluminosilicates with different pore arrangements [1,3,4]: (1) MCM-41-hexagonal two-dimensional (2D) structure with 6 mm space-group symmetry; (2) MCM-48-cubic three-dimensional (3D) system with Ia3d space-group symmetry; and (3) MCM-50-lamellar structure without space-group symmetry. Perhaps the most widely recognized and used ordered mesoporous silica adsorbent is known as MCM-41 [5,6]. ...
... In this context, it is necessary to add that the co-condensation method is usually regarded as a one-pot route, which involves the addition of the organic group, usually a siliceous material, with SiO tetrahedra containing reactive alkoxy groups created during a mesoporous process carried out uniquely. This route traditionally led to functionalized silica adsorbents with both the outer grain surface and the inner surface of the pores [2][3][4][5]. This co-condensation method is called one-pot. ...
A siliceous material in which a framework order was established with a surfactant with sixteen carbon atoms in alkyl chains, MCM-41-C16, was synthesised, surface-modified, and tested regarding the selected physical properties. The pristine material was extracted in an acidic aqueous alcohol and then lined with different surface groups. The properties of four adsorbents were investigated using XRD, X-ray photoelectron spectroscopy, and N2 physisorption techniques. The unit–cell constant was determined from X-ray diffractograms, being in fixed relation to the edge length of the hexagonal frame. The specific surface areas of mesopores and whole crystallites were determined from low-temperature N2-physisorption isotherms. The novelty of this work is a mathematical model of a crystalline microstructure explaining the sizes and shapes of crystalline grains in relation to adsorption features, proposed and successfully tested with the aforementioned experimental data. The roughness of the surface is different from one that is necessary to explain the experimental characteristics quantitatively.
... The recent research in life science technologies is mainly focused on food packaging [137][138][139][140][141][142][143][144][145][146][147][148], nanomaterials applied in medicine (drugs and delivery, nanotoxicology, antibacterial systems, and diagnostics), and nanomaterials for the sensing of environmental conditions [175][176][177][178][179][180][181] (air/water pollution and biological environment). In Table 4 are listed some selected works about life science technology, adding information about possible future research lines. ...
... For this application field, it is important to execute algorithms able to efficiently increase drug delivery by acting on external stimuli (control of targeting according to the spatial distribution of the implanted NPs). Finally, nanomaterials are suitable as detection systems for air and water pollution [175][176][177][178][179][180] and in biological environments to detect reactive oxygen species (ROS) signaling tissue homeostasis [181]. ML analyses could accelerate parameter processes to remove micro-and nano-pollutants or, in biological applications, to combine nanomaterial properties with optical spectroscopic analysis to tune the interactions with cells. ...
The review highlights possible research topics matching the experimental physics of
matter with advances in electronics to improve the intelligent design and control of innovative smart materials. Specifically, following the European research guidelines of Key Enabling Technologies (KETs), I propose different topics suitable for project proposals and research, including advances in nanomaterials, nanocomposite materials, nanotechnology, and artificial intelligence (AI), with a focus on electronics implementation. The paper provides a new research framework addressing the study of AI driving electronic systems and design procedures to determine the physical properties of versatile materials and to control dynamically the material’s “self-reaction” when applying external stimuli. The proposed research framework allows one to ideate new circuital solutions to be integrated in intelligent embedded systems formed of materials, algorithms and circuits. The challenge of the
review is to bring together different research concepts and topics regarding innovative materials to provide a research direction for possible AI applications. The discussed research topics are classified as Technology Readiness Levels (TRL) 1 and 2.
... Silicon-based nanoarchitectured materials, such as MCM-41-based nanomaterials, have in nite advantages when compared to a bulk material, mainly presenting characteristics such as wide and controllable internal surface, well-de ned mesopores, large high surface area, and high stability of mesoporous framework (Costa et al. 2021; Costa et al. 2020b; Costa and Paranhos 2020). The MCM-41based nanostructures concentrates most studies in the M41S family, due to its two-dimensional hexagonal arrangement with P6mm space group symmetry and well-de ned hexagonal network arrangement, it has been widely used with inorganic support (Costa et al. 2021; Costa and Paranhos 2020). ...
... Silicon-based nanoarchitectured materials, such as MCM-41-based nanomaterials, have in nite advantages when compared to a bulk material, mainly presenting characteristics such as wide and controllable internal surface, well-de ned mesopores, large high surface area, and high stability of mesoporous framework (Costa et al. 2021; Costa et al. 2020b; Costa and Paranhos 2020). The MCM-41based nanostructures concentrates most studies in the M41S family, due to its two-dimensional hexagonal arrangement with P6mm space group symmetry and well-de ned hexagonal network arrangement, it has been widely used with inorganic support (Costa et al. 2021; Costa and Paranhos 2020). ...
In the present approach, we investigated the performance of multifunctional nanomaterial MCM-41-Pirkle in the thiacloprid removal in water samples. In the batch adsorption tests, the effects of pH, contact time, initial concentration, and adsorbent dosage were evaluated using the factorial experimental design model and response surface method. The multifunctional MCM-41-Pirkle exhibited well-ordered hexagonal structure with space-group symmetry ( P6mm ), high thermal stability, good textural, structural, and morphological properties, as well as, large pore volume and high surface area. The factorial design was suitable to find the optimized conditions using a smaller number of experiments. Moreover, practically all the effects were significant, which indicates the correct choice of the relevant parameters for the thiacloprid remediation. The MCM-41-Pirkle exhibited a high and fast removal efficiency at a low concentration of thiacloprid, with up to 95.20% of thiacloprid removal in the initial 5 min. It is also possible to observe that the MCM-41-Pirkle has excellent thiacloprid removal potential at different pH values, since the removal efficiency was between 95.01–95.82%. In addition, the Pareto graph displayed the following decreasing order of significance for thiacloprid removal by the multifunctional nanomaterial MCM-41-Pirkle: nanoadsorbent mass > thiacloprid standard concentration > solution pH. Finally, a maximum removal efficiency of 95.83% was achieved at an equilibrium time of 5 min with pH 3 using 40 mg of nanoadsorbent at an initial thiacloprid concentration of 4.5 mg L − 1 .
... Zhao et al. (2000) demonstrated the synthesis of ordered hexagonal SBA-15 with uniform pores of up to 30 nm diameter using an amphiphilic triblock copolymer under highly acidic conditions (pH ~ 1). At pH levels between 2 and 6, which exceed the isoelectric point of silica, there would be no precipitation of silica or gel formation [216]. In a study by Pirez et al. [217], the influence of chloride on the physiochemical properties of SBA-15 was investigated. ...
This review explores the potential of green synthesised SBA-15 nanomaterials in biodiesel production, focusing on their promising application despite their lack of direct use in this field. The growing global demand for sustainable and renewable energy sources has intensified interest in biodiesel as a cleaner alternative to fossil fuels. Biodiesel, derived from renewable biomass sources such as agricultural residues and waste cooking oils, offers significant environmental benefits, including reduced greenhouse gas emissions. Traditional SBA-15 synthesis involves hazardous chemicals, but green synthesis methods using biomass-derived silica present an eco-friendly approach. This review examines the unique structural properties of SBA-15, such as its high surface area and uniform pore structure, which could improve biodiesel production when used as a catalyst. While the green-synthesised SBA-15 has not yet been applied directly in biodiesel production, this article proposes its potential utility and emphasises the need for future research to validate its effectiveness. This novel approach of directly using SBA-15 as a catalyst emphasises its potential to improve biodiesel production sustainability and efficiency, contributing to waste management and renewable energy goals. These findings underscore the scientific value of SBA-15 in the advancement of biofuel technology and highlight its potential for industrial applications.
... Further, abundant surface hydroxyl groups could help integrate the active centers of ILs for specific catalytic applications, and the large pore size is also helpful in transporting multifunctional ILs into the pore channels of SBA-15. For example, Caio and others developed a well-defined organo-functionalized mesoporous catalyst by a one-step reaction [16]. Further, Xie and co-workers reported a series of immobilized ionic liquids on SBA-15 heterogeneous catalysts for biodiesel production reactions [17]. ...
SBA-15 and organic ionic liquid were incorporated in a post-grafting technique for generating a bifunctional ionic liquid embedded mesoporous SBA-15. The prepared heterogeneous catalyst was employed for the first time to synthesize N-alkylated indoline-2,3-dione at mild conditions to afford excellent yields in a short reaction time. The synthesized DABCOIL@SBA-15 catalyst was meticulously characterized by various techniques, such as FT-IR, solid-state 13C NMR, solid-state 29Si NMR, small-angle X-ray diffraction (XRD), and N2 adsorption–desorption. Further, the morphological behavior of the catalyst was studied by SEM and TEM. The thermal stability and number of active sites were determined by thermogravimetric analysis (TGA). The Hammett equation was used to analyze the synergetic effect of the catalyst and substituent effects on the N-alkylated products of 5-substituted isatin derivatives, which resulted in a negative slope. This negative slope indicates a positive charge in the transition state. Notably, the DABCOIL@SBA-15 catalyst demonstrated its practicality by being reused for seven cycles with consistently high catalytic activity.
... (Vallet-Regi et al., 2001) examined for the first time the applications of mesoporous silica in the drug delivery of ibuprofen. MCM-41 belongs to the M41S family along with other types such as MCM-48 (Khader et al., 2024) with (3D) cubic system and Ia3d space group symmetry; and MCM-50 with lamellar structure without space-group symmetry (Fig. 2) (Costa et al., 2021). SBA-n (Santa Barbara Amorphous) is another family of MSNs that has attracted researchers due to their large pore sizes (4.6-30 nm), thick pore walls, and high hydrothermal stability compared with other types of MSNs. ...
Oral drug administration remains one of the most convenient routes due to its Simplicity, high patient
compliance, and cost-effectiveness. However, many medicinal products available on the market exhibit poor
water solubility, which adversely affects the dissolution rate of drugs in biological fluids. Drug loading is a
promising strategy to produce highly stable amorphous drugs with improved dissolution rates, solubility, and
bioavailability. Mesoporous silica nanoparticles (MSNs) are particularly advantageous due to their tunable
surface area, pore size, and pore volume, making them suitable to load various molecules such as drugs, genes,
and proteins. The use of mathematical models is crucial for predicting and analyzing the release profile of active
molecules and diffusion patterns within delivery systems. This enables the design and development of new
systems with more desirable release patterns. This review provides an overview of MSNs and drug loading
methods, discusses the mechanisms of drug release and release kinetic models using mesoporous carriers, and
highlights critical considerations in designing MSNs, such as particle stability and cytotoxicity.
... Mesoporous silica-based nanostructured materials can find extensive application in environmental remediation, significantly reducing the presence of harmful compounds in environmental matrices (water, air, and soil) [8][9][10]. Indeed, due to the wide array of harmful compounds stemming from various industrial activities such as pharmaceutical, metallurgical, and petroleum industries, applying traditional decontamination treatments (coagulation, flocculation, filtration, and others) proves challenging [11][12][13], while remediation using hybrid nanostructured systems based on mesoporous silica can allow highly specific interactions potentially able to address various criticalities [14]. ...
Mesoporous silica-based nanomaterials have emerged as multifunctional platforms with applications spanning catalysis, medicine, and nanotechnology. Since their synthesis in the early 1990s, these materials have attracted considerable interest due to their unique properties, including high surface area, tunable pore size, and customizable surface chemistry. This article explores the surface properties of a series of MSU-type mesoporous silica nanoparticles, elucidating the impact of different functionalization strategies on surface characteristics. Through an extensive characterization utilizing various techniques, such as FTIR, Z-potential, and nitrogen adsorption porosimetry, insights into the surface modifications of mesoporous silica nanoparticles are provided, contributing to a deeper understanding of their nanostructure and related interactions, and paving the way to possible unexpected actionability and potential applications.
... The adsorption of CO 2 is higher in the case of microporous materials, but mesoporous ones are preferred because they can be used as a support which can be functionalized by different amines. Amino groups favor CO 2 adsorption due to the physical and chemical interactions between functionalized species and CO 2 molecules [6][7][8][9]. ...
The mesoporous silica KIT-6 was synthesized and functionalized with 3-aminopropyltriethoxysilane (APTES) by grafting at 110 °C. The composites were prepared with three different concentrations of APTES: 20, 30 and 40 wt.%. The as-prepared samples were characterized by thermal gravimetric analysis in air and nitrogen atmosphere (TG/DTA), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction and nitrogen adsorption–desorption. In this study, CO2 adsorption–desorption was investigated using temperature programmed desorption mass spectrometry (TPD-MS) at different temperatures. The adsorption capacity of the prepared composites is 2.23 mmol CO2/g at 40 °C and decreases to 0.95 mmol/g at 70 °C. Regarding the efficiency of the amino groups, the best result was obtained for APTES-grafted KIT-6 at 40 °C, with 0.512 mmol CO2/mmol NH2. The results showed good cyclical stability in adsorption capacities even after nine adsorption–desorption cycles.
... While the extensive use of silicon-containing mineral catalysts such as silica [93], nanosilica [94,95], zeolites [96,97], SBA [98][99][100], and aluminosilicates [101] has been widely reported in scientific literature by researchers, the approach shifts when it comes to organosilicon compounds. Organosilicons, or silicon-containing organic compounds, offer a distinct perspective compared to their mineral counterparts. ...
Organosilicon compounds play a crucial role as essential building blocks and valuable organic molecules in various materials. They are extensively utilized as synthetic intermediates in chemical synthesis processes. Recent studies have highlighted the multifaceted role of silicon compounds, showcasing their significance not only as reactive participants or products but also as potent catalysts in various chemical reactions, as reported by researchers. In this comprehensive review, our objective is to provide a summary of recent advancements in synthesizing various organosilicon compounds in formation of silicon–carbon, silicon–oxygen, silicon–nitrogen and explore the applications of siliconic materials as catalysts in polymerization, reduction, and isomerization processes. Emphasizing the significant potential of this methodology, we aspire to inspire further research and applications in this rapidly emerging field. Furthermore, this review covers over 50 years of research on organosilicon chemistry in CCERCI under supervision of Prof. Seyed Mohammad Bolourtchian.
... In the last years, micelle-templated mesoporous silica materials have emerged as a solution for the development of many applications as catalysts or supports for pollutant removal, drug delivery systems, or biocompatible implants. [1][2][3][4] These applications demand the control of pore size, accessibility, morphology, stability and surface functionalization by various tailored synthesis strategies on surfactant packing and transformation of the liquid crystalline phase. Among the methods most used in the synthesis of mesoporous silica materials is soft templating in which a surfactant or amphiphilic block copolymer directs the mesoporous material synthesis by forming micelles in solution, around which the silica precursor will be polymerized under hydrothermal conditions. ...
Three surfactants were selected from a series of EOx/POy/EOx triblock copolymers and ethoxylated octylphenol as nonionic templating agents for the synthesis of silica mesoporous materials at room temperature and by hydrothermal treatment. The surfactants were ethylene oxide-propylene oxide-ethylene oxide tri-block copolymers (Pluronic F68) and a polydisperse ethoxylated octylphenol (Triton X-100). The obtained materials were compared with SBA-15 mesoporous silica synthesized with Pluronic P123 surfactant and were used as support to obtain Ni and NiTi-silica catalysts (2.5% NiO, 5% TiO2). The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, IR and UV-Vis spectroscopy. Catalytic and photocatalytic activity of Ni and NiTi-silica samples were tested, with and without H2O2, for phenol and Brilliant Blue FCF dye oxidative degradation in the liquid phase. The obtained results showed a significant effect of surfactant on silica structure, morphology and texture, and catalytic and photocatalytic properties.
... Adsorption kinetics can help to identify the adsorption mechanisms, such as diffusion and chemical reactions, which quantifies the adsorption dynamics for an adsorbate-adsorbent system [19,20]. The rate of adsorption depends on the physical and chemical properties of the adsorbent [21,22] and the operating conditions [23,24]. There are several kinetic models in the literature, such as pseudo-first-order (PFO), pseudo-secondorder (PSO), intra-particle diffusion (IPD), and Elovich kinetic models, which quantify the dynamics of adsorption. ...
Recently, considerable attention has been given to using magnetic nanoparticles (MNPs) for capturing oil from oil-in-water (O/W) emulsions, despite MNPs’ inherent instability and agglomeration. Their stabilization through changing surface chemistry is required to increase dispersivity. In this research, we use cetyltrimethylammonium bromide (CTAB) as a cationic surfactant to increase the positive surface charge of the particles, resulting in a better stability in the aqueous solution because of increased repulsive forces. The functionalized MNPs are characterized using transmission electron microscopy (TEM), zeta potential, and contact angle (CA) measurements. The aim of this study is to investigate the oil separation efficiency (SE) and equilibrium oil adsorption capacity of the synthesized particles, which are determined using gas chromatography analysis. We also study the adsorption behavior using isotherm and kinetic models. The SE values indicate the superior performance of MNP@CTAB for oil adsorption from dodecane-in-water nanoemulsion (SE = 99.80%) compared to the bare MNPs with SE of approximately 57.46%. These findings are attributed to the stronger electrostatic attraction between the MNP@CTAB having high positive charge and negatively charged oil droplets. The adsorption isotherm results using both linear and non-linear regression methods show that the Freundlich isotherm is the best fit to the experimental equilibrium data (with calculated R2 > 0.97), verifying a multilayer heterogeneous adsorption. Moreover, the pseudo-first-order kinetic model describes the experimental equilibrium data in a greater congruence (R2 = 0.99), suggesting physical adsorption of oil onto MNPs through van der Waals and physical bonding, which is also confirmed through zeta potential measurements.
... On the other hand, since the first report of mesoporous silica through nanostructured self-assembly technique by Mobil Corporation in 1992 [23], mesoporous materials have been considered to be one of the most important materials in adsorption [24,25], catalysis [26,27] and drug delivery [28,29]. Taking them as the main body, regular-structured conducting polymer nanofibers with porosity and internal structure can be fabricated through taking advantage of the unique structure. ...
Mesoporous silica/polyaniline (PANI) composite nanofibers with a full interpenetrating structure were synthesized via a controlled sol–gel process and in situ polymerization route from anodic alumina oxide (AAO) membranes. In the synthetic process, AAO membranes act as a template for the preparation of PANI/silica composite fibers. After removal of the AAO templates by hydrochloric acid (HCl) dissolution, the as-prepared mesoporous silica/PANI composite fibers possess a uniform fiber morphology and full interpenetrating structure, resulting in a continuous conductive PANI network with high porosity and large specific surface area. SEM images of mesoporous silica/PANI composite fibers shows that the diameter of the silica fibers has not been changed before and after PANI deposition, proving that PANI is well filled in the channel. The nitrogen (N2) absorption/desorption experiments suggest that the average pore size and the surface area of silica/PANI composite fibers are 5.7 nm and 147 m²/g respectively. The profile of isotherms is similar to that of blank silica nanofibers with lower adsorption capacity and relative pressure, which demonstrates that aniline can polymerize in the pore channel. The results of four-probe method show that the conductivity of the mesoporous silica/PANI composite fibers is 2.6 × 10–4 S/cm. This synthetic strategy is also suitable for fabricating various nanostructured composite nanofibers of PANI and other inorganic materials.
Graphical abstract
... The suspension was filtered and washed with copious amounts of deionized water and dried for 12 h at 368 K. Finally, the solid was calcined at a 823 K for 6 h at 0.8 K min −1 heating rate. The incipient impregnation method was used to incorporate Zn into SBA-15, with zinc nitrate hexahydrate (Zn (NO 3 ) 2 6 H 2 O) as a precursor equivalent to a 2% wt metal content [21,33]. ...
SBA-15 and Zn/SBA-15 mesoporous materials were synthesized by coprecipitation and incipient impregnation methods, respectively. Both materials were tested as adsorbents of quinoline (Q) adsorption in the presence of dibenzothiophene (DBT), changing temperature and nitrogen concentration. The textural and structural adsorbents results revealed that the Zn incorporation reduced the pore volume and the surface area by 23% and 27%, respectively, compared to the SBA-15 adsorbent. However, both adsorbents presented a hexagonal structure in the form of cylindrical channels of ordered porosity with a domain of (100), (110) and (200) crystalline planes. SEM micrographs of the SBA-15 adsorbent showed rod-shaped particles with 1.20 × 0.65 μm dimensions. Zn incorporation did not significantly change the final SBA-15 morphology. In general, the Q removal percentage in the presence of DBT for the SBA-15 adsorbent at different nitrogen concentrations was between 10 and 20% higher than for the Zn/SBA-15 adsorbent at 308, 315, 323, and 336 K, associated with the basic nature of Q. However, the highest sulfur removal was observed at 308 K, where the Zn/SBA-15 adsorbent showed 2.5 times more sulfur removal compared to the SBA-15 adsorbent. For both adsorbents, the pseudo second-order kinetic model better fitted the Q adsorption data in the presence of DBT compared to the first-order model. Langmuir and Freundlich models were studied to describe the adsorption parameters of Q at different concentrations and temperatures, the experimental data were adjusted to a Langmuir-type isotherm at temperatures from 308–328 K using mesoporous adsorbents. Additionally, thermodynamic parameters of Q adsorption in the presence of DBT were determined and the parameters like a Gibbs free energy (ΔG⁰), adsorption enthalpy (ΔH⁰) and adsorption entropy (ΔS⁰) were estimated. The results of thermodynamics study and adsorption parameters indicated that the removal of Q in both adsorbents was a spontaneous and exothermic process, and the SBA-15 adsorbent at various nitrogen concentrations and low temperatures obtained high capacities and rates of Q adsorption in DBT presence.
Graphical Abstract
Particle size distribution and separation factor for SBA-15 and Zn/SBA-15 adsorbents in Quinoline (Q) adsorption as a function of operating temperature.
... These materials can also be easily functionalized by either co-condensation or post-grafting methods thanks to the presence of silanol groups and the large variety of silane molecules [25][26][27][28][29][30][31]. Tuning the surface chemistry of the pores opened new opportunities for developing mesoporous silica solids with very specific properties suitable for industrial applications such as adsorption processes, membrane separation, catalysis, drug delivery, or bio-sensing [32][33][34][35][36][37]. For example, Nguyen et al. reported that the functionalization of SBA-15 with amine groups results in an increase of the maximum adsorption capacity compared to that of the pristine SBA15 (for urea: 1644.7 mg. ...
Background
Pristine SBA-15 and amine or thiol-functionalized SBA-15 materials were synthesized, characterized, and highlighted by studying the glutathione (GSH) adsorption process in aqueous solutions.
Methods
In this study, SBA-15 mesoporous materials were functionalized with 3-aminopropyltriethoxysilane (APTS) and (3-mercaptopropyl)triethoxysilane (MPTES) in order to introduce amine and thiol groups onto the surface by using a post-grafting method, respectively. For comparison, the SBA-15-based materials were used as adsorbents to further investigate the adsorption behaviour of GSH under various experimental conditions.
Significant findings
To examine the underlying mechanism of the adsorption process, the kinetics of the GSH adsorption onto SBA-15-based adsorbents were fitted using pseudo-first order, pseudo-second order, Elovich, and Aharoni models. Adsorption isotherms showed that the Freundlich isotherm model was the most appropriate to simulate the adsorption of GSH molecules onto SBA-15-NH2 adsorbent and the Langmuir isotherm model for the two other substrates. In addition, the adsorption thermodynamics confirmed the exothermic behaviour of GSH adsorption process onto the SBA-15-SH adsorbent. In contrast, the capture of GSH molecules by the SBA-15-OH and SBA-15-NH2 adsorbents follows an endothermic reaction process. Finally, the adsorption nature of GSH onto SBA-15 adsorbents is classified as physisorption.
... Therefore, the covalent anchoring of Schiff base complexes onto a functionalized siliceous mesoporous material with large pore diameters seems to be promising, especially for catalytic applications [32][33][34]. Ordered mesoporous silica are interesting solid supports due to their uniform and large pores, tunable pore sizes, highsurface areas, defined surface acidity, excellent mechanical stability, and high concentration of surface Si-OH groups for the binding of the catalyst active sites [35][36][37]. In particular, MCM-41 (2d hexagonal p6mm), MCM-48 (3d cubic Ia3d), and SBA-15 (large-pore 2d hexagonal p6mm) mesoporous silica are used as supports with a high specific surface area (600-1000 m 2 g −1 ) and narrow pore size distribution (pore diameter~3-10 nm) [38]. ...
New series of Cu(II) and Mn(II) complexes with Schiff base ligands derived from 2-furylmethylketone (Met), 2-furaldehyde (Fur), and 2-hydroxyacetopheneone (Hyd) have been synthesized in situ on SBA-15-NH2, MCM-48-NH2, and MCM-41-NH2 functionalized supports. The hybrid materials were characterized by X-ray diffraction, nitrogen adsorption–desorption, SEM and TEM microscopy, TG analysis, and AAS, FTIR, EPR, and XPS spectroscopies. Catalytic performances were tested in oxidation with the hydrogen peroxide of cyclohexene and of different aromatic and aliphatic alcohols (benzyl alcohol, 2-methylpropan-1-ol, and 1-buten-3-ol). The catalytic activity was correlated with the type of mesoporous silica support, ligand, and metal–ligand interactions. The best catalytic activity of all tested hybrid materials was obtained in the oxidation of cyclohexene on SBA-15-NH2-MetMn as a heterogeneous catalyst. No leaching was evidenced for Cu and Mn complexes, and the Cu catalysts were more stable due to a more covalent interaction of the metallic ions with the immobilized ligands.
Pyrene derivative is used as a molecular probe to investigate the interactions in hybrid mesoporous films through fluorescence spectroscopy. The dynamic formation of pyrene excimer provides insight into the nanoscale organization of the material.
This work highlights modern approaches to the production and areas of practical application of composite sorption-active materials based on inorganic sorbents. The physicochemical properties and parameters of the porous structure of composite sorbents are shown. Emphasis is placed on controlled sorption processes using various types of energy by means of an example of inorganic sorbents. Methods for producing sorption materials from alternative raw materials represented by inorganic technogenic waste are analyzed.
Mesoporous ceria nanoparticles featured with ordered pores (O-MCNs) are much more potential than their counterparts featured with interparticle pores (I-MCNs) due to their uniform pore size and interconnected framework structures....
Получение сорбентов из отходов является важной задачей современной промышленности, решение которой позволит устранить целый ряд насущных проблем. В данной работе исследуется влияние изменения параметров процесса получения композиционных сорбционно-активных материалов (КСАМ) состава “технический углерод – глинистый материал” из техногенных отходов на параметры пористой структуры. Показана зависимость изменения характеристик материала от количественного соотношения компонентов и вида глинистого материала. При изменении вида глинистого материала изменяется прочность КСАМ, при этом пористая структура материала практически не претерпевает изменения. Установлено, что при изменении температуры спекания изменяется удельная площадь поверхности при постоянстве предельного объема сорбционного пространства.
Imidazole molecules entrapped in porous materials can exhibit high and stable proton conductivity suitable for elevated temperature (>373 K) fuel cell applications. In this study, new anhydrous proton conductors based on imidazole and mesoporous KIT-6 were prepared. To explore the impact of the acidic nature of the porous matrix on proton conduction, a series of KIT-6 materials with varying Si/Al ratios and pure silica materials were synthesized. These materials were additionally modified with cerium atoms to enhance their Brønsted acidity. TPD-NH3 and esterification model reaction confirmed that incorporating aluminum into the silica framework and subsequent modification with cerium atoms generated additional acidic sites. UV-Vis and XPS identified the presence of Ce3+ and Ce4+ in the KIT-6 materials, indicating that high-temperature treatment after cerium introduction may lead to partial cerium incorporation into the framework. EIS studies demonstrated that dispersing imidazole within the KIT-6 matrices resulted in composites showing high proton conductivity over a wide temperature range (300–393 K). The presence of weak acidic centers, particularly Brønsted sites, was found to be beneficial for achieving high conductivity. Cerium-modified composites exhibited conductivity surpassing that of molten imidazole, with the highest conductivity (1.13 × 10−3 S/cm at 393 K) recorded under anhydrous conditions for Ce-KIT-6. Furthermore, all tested composites maintained high stability over multiple heating and cooling cycles.
The application of mesoporous silica nanoparticles (MSN) as smart containers to distribute corrosion inhibitors gradually over time for metal protection has been well documented. This material possesses unique properties such as tunable surface and pore, high thermal and chemical stability, large pore volume and pore size, relatively low toxicity, and water solubility. These properties of MSN enable it to encapsulate large volumes of corrosion inhibitors which upon installation of an appropriate gatekeeper can release inhibitors at a controlled rate thereby improving the service life of coatings when dispersed within. In this mini-review, we look at the structure and properties of MSN, various synthetic routes reported in the literature, the nucleation and growth mechanism proposed thus far, some of the challenges still encountered in the synthesis of MSN as well as various ways it has been applied as a “smart” container for the controlled release of corrosion inhibitors in coatings.
Singlet oxygen is a powerful oxidant used in various applications, such as organic synthesis, medicine, and environmental remediation. Organic and inorganic photosensitizers are commonly used to generate this reactive species through energy transfer with the triplet ground state of oxygen. We describe here a series of novel benzophenazine derivatives as a promising class of photosensitizers for singlet oxygen photosensitization. In this study, we investigated the structure‐activity relationship of these benzophenazine derivatives. Akin to a molecular compass, the southern fragment was first functionalized with either aromatic tertiary amines, alkyl tertiary amines, aromatic sulfur groups, alkyl sulfur groups, or cyclic ethers. Enhanced photophysical properties (in terms of triplet excited‐state lifetime, absorption wavelength, triplet state energy, and O2 quenching capabilities) were obtained with cyclic ether and sulfur groups. Conversely, the presence of an amine moiety was detrimental to the photocatalysts. The western and northern fragments were also investigated and slightly undesirable to negligible changes in photophysical properties were observed. The most promising candidate was then immobilized on silica nanoparticles and its photoactivity was evaluated in the citronellol photooxidation reaction. A high NMR yield of 97 % in desired product was obtained, with only a slight decrease over several recycling runs (85 % in the fourth run). These results provide insights into the design of efficient photosensitizers for singlet oxygen generation and the development of heterogeneous systems.
p>This study successfully synthesized mesoporous silica using the template methyl ester ricinoleate (MS-TMR) and further functionalized the MS-TMR surface with 3-aminopropyltriethoxysilane (APTES). The functionalization of MS-TMR with APTES was achieved through a 48-hour grafting method. For the adsorption experiments, 20 mg of both MS-TMR and MS-TMR-APTES adsorbents were employed to remove Ni(II) from aqueous solutions at a concentration of 30 mg/L and pH 6. The objective was to assess the adsorption capacity and to characterize the synthesized adsorbents. Characterization was conducted using Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). FTIR analysis revealed that the MS-TMR adsorbent possessed silanol (Si-OH) and siloxane (Si-O-Si) groups. Conversely, the MS-TMR-APTES adsorbent exhibited additional amine (N-H) and C-H groups after the APTES grafting. XRD results indicated that both samples were amorphous. The concentration of Ni(II) ions was determined using Atomic Absorption Spectroscopy (AAS), which facilitated the calculation of removal percentages and adsorption capacities. MS-TMR achieved a mere 3.54% removal of Ni(II) ions, corresponding to an adsorption capacity of 3.21 mg/g. In contrast, MS-TMR-APTES demonstrated significantly enhanced performance, removing 54.23% of Ni(II) ions with an adsorption capacity of 48.81 mg/g. The findings suggest that APTES-functionalized MS-TMR has considerable potential for removing Ni(II) ions and could be explored further for the adsorption of other heavy metal ions.</p
This research work aims to develop low-cost hybrid polymeric membranes with high chiral resolution capacity. Mesoporous materials (MCM-41) obtained from rice husk biomass was used to support the chiral selector...
Mesoporous silica nanoparticles (MSNs) are recognized as a prime example of nanotechnology applied in the biomedical field, due to their easily tunable structure and composition, diverse surface functionalization properties, and excellent biocompatibility. Over the past two decades, researchers have developed a wide variety of MSNs-based nanoplatforms through careful design and controlled preparation techniques, demonstrating their adaptability to various biomedical application scenarios. With the continuous breakthroughs of MSNs in the fields of biosensing, disease diagnosis and treatment, tissue engineering, etc., MSNs are gradually moving from basic research to clinical trials. In this review, we provide a detailed summary of MSNs in the biomedical field, beginning with a comprehensive overview of their development history. We then discuss the types of MSNs-based nanostructured architectures, as well as the classification of MSNs-based nanocomposites according to the elements existed in various inorganic functional components. Subsequently, we summarize the primary purposes of surface-functionalized modifications of MSNs. In the following, we discuss the biomedical applications of MSNs, and highlight the MSNs-based targeted therapeutic modalities currently developed. Given the importance of clinical translation, we also summarize the progress of MSNs in clinical trials. Finally, we take a perspective on the future direction and remaining challenges of MSNs in the biomedical field.
This work proposes the activated mechanical alloyed composite catalysts by in-situ O2 heat treatment (CuxSn100−xO2HT). The catalytic activity of catalysts is improved tremendously for the phenol hydroxylation by superoxide (O2−). The conversion is almost 100% and selective to 94% catechol (CAT). To understand the formation of superoxide, in situ time-resolved Cu K-edge and Sn L3-edge X-ray absorption spectroscopy explain the contribution of an oxygen atom to the CuxSny composites. Meanwhile, in-situ XAS with O2 heat treatment depicts how superoxide bonded on CuxSny composites. Quantitatively, H2-TPR and curve fitting ATR-FTIR determine the total amount of superoxide on MAed CuxSn100−xO2HT and distinguish the numbers of O2− on Cu and Sn sites in CuxSn100−xO2HT. EPR explains that the hybridization of d-orbitals of Cu2+ and p-d orbitals of Sn4+ shifted the g-factor of a free electron in superoxide. XPS depth profiling of O 1s reveals identical superoxide on the composite CuxSnyO2HT catalysts. After optimizing the Sn contents, Cu30Sn70O2HT exhibits the highest catalytic activity and a number of superoxides, giving the CAT 183 μmol in conjunction with reducing tar contents. Extended X-ray absorption fine structure (EXAFS) illustrates the present compressive strain of Cu–O distance and is essential in increasing the quantity of CAT. The work presents how mechanical alloying can be a potential free-solvent catalyst synthesis.
The mesoporous SBA‐15 was synthesized in acidic conditions by hydrothermal method using Pluronic surfactant P123. A combination of SeO2, TiO2, and CuO was loaded in SBA‐15 in pairs or singly. Synthesized SBA‐15 and some loaded mesoporous materials were characterized using several standard techniques. The efficiency of the synthesized photocatalysts was verified for the decomposition of two different dyes (methylene blue (MB) and methyl green (MG)) under ultraviolet and visible light radiation. The results show that the synthesized photocatalyst based on SBA‐15 with 5 % by weight of TiO2 and 5 % by weight of SeO2 has better performance (about 98 % of MB or MG were degraded within 120 min under UV radiation). Also, the photocatalyst with 5 % by weight of SeO2 and 5 % by weight of CuO shows a good performance for the degradation of the dyes under visible irradiation in the presence of H2O2 (complete elimination of MB and MG within 150 and 75 min, respectively). The scavenging test shows that superoxide has a governing role for the degradation of the dyes. The photocatalysts are reusable and they could preserve more than 74 % of the efficiency following 4 times of consecutive use for the degradation of the dyes.
The lipid-inspired biosilicification process enables the creation of a series of concave silica nanoarchitectures in the complex shapes of nanobowls, nanodishes, nanoboats, and nanoloops. The reaction at a pH of 8 initially allows the formation of thin and elastic circular gel nanosheets that can undergo inducible stretching and folding, which subsequently evolves into nanodish and nanobowl through a potential global buckling process. The adjustment of the pH to 9 and 4 enables the production of more complex morphogens of nanoboat and nanoloop, respectively. These unique silica nanoarchitectures may have a wide scope of potential application from nanoreactors in heterogenous catalysis to drug delivery systems and optical materials.
Earth‐abundant photosensitizers are highly sought after for light‐mediated applications, such as photoredox catalysis, depollution and energy conversion schemes. Homoleptic and heteroleptic copper(I) complexes are promising candidates in this field, as copper is abundant and the corresponding complexes are easily obtained in smooth conditions. However, some heteroleptic copper(I) complexes suffer from low (photo)stability that leads to the gradual formation of the corresponding homoleptic complex. Such degradation pathways are detrimental, especially when recyclability is desired. This study reports a novel approach for the heterogenization of homoleptic and heteroleptic Cu complexes on silica nanoparticles. In both cases, the photophysical properties upon surface immobilization were only slightly affected. Excited‐state quenching with aryl diazonium derivatives occurred efficiently (10⁸–10¹⁰ M⁻¹ s⁻¹) with heterogeneous and homogeneous photosensitizers. Moderate but almost identical yields were obtained for the α‐arylation of enol acetate using the homoleptic complex in homogeneous or heterogeneous conditions. Importantly, the silica‐supported photocatalysts were recycled with moderate loss in photoactivity over multiple experiments. Transient absorption spectroscopy confirmed that excited‐state electron transfer occurred from the homogeneous and heterogeneous homoleptic copper(I) complexes to aryl diazonium derivatives, generating the corresponding copper(II) center that persisted for several hundreds of microseconds, compatible with photoredox catalysis applications.
Mesoporous silica‐based materials are used as sorbents and supports in many fields. The ordered pore architecture of MCM‐41, and the absence of interconnections, make it suitable as a model system. The surface is natively functionalized by many silanol groups, endowing the material with a polar surface to directly interact with the target species or to mount additional functional groups. Either bare or functionalized, surface silanol arrangement is crucial to material performance. In the case of CO 2 capture with amine‐functionalized silica, silanol groups are responsible for fundamental H‐bonds during chemisorption, but they also modulate the effect and weight of humidity on the material performance. In addition, the silanol groups can also tune the weight of physisorption over chemisorption. The relationship between these aspects and the textural features of mesostructured silica has not been addressed in detail. In this study, computer models are employed to investigate the adsorption capacity and selectivity of bare mesostructured silica with three different pore sizes. Results are rationalized in terms of silanol surface density and pore curvature. The importance of the energetic inequivalence between Q ³ and Q ² sites on the silica surface is emphasized, as this causes adsorption behavior to deviate from ideality.
The potential of microporous zeolites FAU and BEA, and mesoporous MCM-41, for prolonged release of atenolol in drug delivery systems was investigated both experimentally, using drug release studies, and theoretically using classical molecular dynamics simulations.
Remarkably, zero-order release of atenolol was achieved from FAU (SiO2/Al2O3 = 80:1) into phosphate buffer for 24 h followed by prolonged release for at least another 48 h. Experimental data also demonstrate the ability for all of the drug-zeolite combinations investigated to achieve prolonged release of atenolol, with the release rates determined by the combination of framework topology, aluminium content and drug release study media.
Molecular dynamics simulations give an insight into the reasons for the different release rates observed for FAU and BEA. The results of this work emphasise the need for sophisticated models in order to model subtle differences in release, such as those observed at different SiO2/Al2O3 ratios.
Great progress has been made in the preparation and application of mesoporous metal oxide films and materials during the last three decades. Numerous preparation methods and applications of these novel and interesting materials have been reported, and it was demonstrated that mesoporosity has a direct impact on the properties and potential applications of such materials. This Special Issue of Coatings contains a series of ten research articles demonstrating emphatically that various metal oxide materials could be prepared using a number of different methods, and focuses on many areas where these mesoporous materials could be used, such as sensors, solar cells, supercapacitors, photoelectrodes, anti-corrosion agents and bioceramics. Our aim is to present important developments in this fast-moving field, from various groups around the world.
Three series of poly(ethylene-co-vinyl acetate)/mesoporous silica type SBA-15 (EVA/SBA-15) nanocomposites, containing 1, 2, 3, and 4 wt% SBA-15 nanoparticles were prepared by melt blending in internal mixer. The mesoporous silica SBA-15 was synthesized by the sol-gel method and organomodified by Hexadecyltrimethoxysilane (HDTMS). The terpolymer of Ethylene-butyl acrylate-maleic anhydride (E-BA-MA) containing 6% butylacrylate, 3% maleic anhydride was added as compatibilizer at 2 wt% to nanocomposites including unmodified SBA-15. The chemical and physical properties of EVA/SBA-15 nanocomposites were characterized by infrared spectroscopy (FTIR), calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and rheology. The results confirmed that HDTMS was successfully incorporated into the surface of SBA-15. The crystallinity of the matrix decreased and Young’s modulus increased with the incorporation of the filler and in the presence of terpolymer as compatibilizer, whereas elongation at break and tensile strength kept almost the values of the matrix. The thermal stability of nanocomposites was enhanced as compared with the pure EVA matrix.
Crosslinked chitosan-ethylene glycol diglycidyl ether (CTS-EGDE) was modified by loading fly ash (FA) particles into its polymeric matrix to improve the adsorptive removal of reactive red 120 (RR120) dye. The Box–Behnken design was used to assist in the tuning of optimum synthesis and adsorption conditions, such as the loading ratio of FA particles (A: 0–50%), adsorbent dose (B: 0.02–0.08 g), solution pH (C: 4–10), temperature (D: 30 °C–60 °C), and time (E: 20–60 min). The highest removal rate (98.8%) of 50 mg/L RR120 dye was achieved under the following conditions: FA loading, 25% (CTS-EGDE/FA-25); adsorbent dose, 0.05 g; solution pH, 4; temperature, 60 °C; and time, 40 min. The maximum adsorption capacity of CTS-EGDE/FA-25 for RR120 was 220 mg/g at 60 °C. This work provides insights into the optimization of the synthesis of composite materials, which can potentially be applied in wastewater treatment.
Mesoporous silica, namely SBA-15, has been used for enzyme immobilization to help improve thermal stability of the enzymes and, in some cases, increase the enzymatic activity. It has been shown that morphology of SBA-15 is one of the factors influencing kinetics of enzyme adsorption. We reported, here, the adsorption kinetics and peroxidase activity of cytochrome c (cytc) in spherical SBA-15 in comparison of three different rod-like (fibrous, fiber, and rope) SBA-15 samples. The experimental adsorption profile fitted much better to the pseudo-second order than the pseudo-first order model. The maximum loading capacity of cytc was 466, 423, 390, and 352 mg/g for fibrous, rope, fiber, and spherical SBA-15, respectively. The rate constant for cytc adsorption for spherical SBA-15 was 3 times slower than rope and fiber SBA-15, and 15 times slower than fibrous SBA-15. The activity of cytc after immobilization in SBA-15 samples depended on the amount of cytc loading. The cytc loading in all SBA-15 at lower than 10 µmol/g showed higher activity than in free cytc in solution. The maximum activity of immobilized cytc was found in spherical SBA-15 at cytc loading of 1.00 µmol/g (~ 7 times higher than in free cytc). Finally, the Fe(III) at the heme group of cytc/SBA-15 samples with high activity was examined to contain high-spin state. The investigation in this work could suggest useful information for the preparation of SBA-15 for enzyme immobilization to appropriate applications, such as drug delivery.
Mesoporous ruthenium catalysts (0.74–3.06 wt%) based on ordered Mobil Composition of Matter No. 41 (MCM-41) silica arrays on aluminosilicate halloysite nanotubes (HNTs), as well as HNT-based counterparts, were synthesized and tested in benzene hydrogenation. The structure of HNT core-shell silica composite-supported Ru catalysts were investigated by transmission electron microscopy (TEM), X-ray fluorescence (XRF) and temperature-programmed reduction (TPR-H2). The textural characteristics were specified by low-temperature nitrogen adsorption/desorption. The catalytic evaluation of Ru nanoparticles supported on both the pristine HNTs and MCM-41/HNT composite in benzene hydrogenation was carried out in a Parr multiple reactor system with batch stirred reactors (autoclaves) at 80 °C, a hydrogen pressure of 3.0 MPa and a hydrogen/benzene molar ratio of 3.3. Due to its hierarchical structure and high specific surface area, the MCM-41/HNT composite provided the uniform distribution and stabilization of Ru nanoparticles (NPs) resulted in the higher specific activity and stability as compared with the HNT-based counterpart. The highest specific activity (5594 h−1) along with deep benzene hydrogenation to cyclohexane was achieved for the Ru/MCM-41/HNT catalyst with a low metal content.
In order to accomplish efficient CO2 capture, poly(ethyleneimine) (PEI) and tetraethylenepentamine (TEPA), with commonly used and inexpensive, was codispersed into the as-prepared SBA-15 (SBA-15(p)) to prepared blended amine functionalized adsorbent. The influence of the mass ratio of PEI to TEPA on the adsorption property was investigated. The promoting effects of TEPA on CO2 capture property were investigated. The adsorbents were characterized using N2 adsorption/desorption, Fourier transform infrared spectroscopy (FTIR), Transmission electron microscope (TEM) and in situ diffuse reflectance infrared fourier transform spectroscopy (in situ DRIFTS). Among the prepared adsorbents, the SBA-15(p) with 30 wt% PEI and 40 wt% TEPA has the CO2 capture capacity of 4.64 mmol/g and the optimal amine efficiency (0.359 molCO2/molN) at 75 °C with 20 vol% CO2 in N2. The addition of TEPA species could improve the CO2 adsorption amount with high amine utilization. The P123 with wheel-like distribution in SBA-15(p) promotes the CO2 capture by optimizing the accessibility of amine to the CO2. After 15 adsorption cycles, the SBA-15(p) with 40 wt% PEI and 30 wt% TEPA has better reusability and cyclic performance, the adsorption capacity can keep around 4.13 mmol/g. The result indicated that more PEI in the adsorbent would improve the adsorbent cyclic stability. Meanwhile, the in-situ DRIFTS results suggested that the reaction of CO2 molecule with the amine active sites in the adsorbent, agrees with anionic and cationic mechanisms.
Since 1990 and the invention of the very first generation of ordered mesoporous silica materials, several innovative methodologies have been applied to synthesize, characterize, and modify silica/non-silica mesoporous materials. The growth of the mesoporous materials field has generated significant environmental and economic advantages compared to various other industrial developments. According to the literature, there are several key synthesis approaches and parameters that can affect the structural, textural and morphological characteristics of mesoporous materials. To date, huge attempts have been made to maximize the activities and selectivities of these materials through either the in situ or post-synthesis functionalization of the large interior surface areas and internal mesostructured frameworks in the presence of specific organic/inorganic components. However, the main challenge is to provide good control over the incorporation and distribution of multiple guest components within the mesostructured hosts. Mesostructured materials have received great attention for various applications, such as being used in electronics, medicine, photocatalysis, catalyst supports, catalysis, absorbers, sensors, gas separation, etc. In the current paper, several recent developments have been highlighted and reviewed regarding the fabrication and characterization of siliceous/non-siliceous mesoporous materials via various synthetic approaches. Furthermore, the availability of diverse functionalization methods has been reviewed to provide comprehensive approaches for synthesizing new generations of suitably modified mesoporous materials with superior structural, physicochemical, and textural characteristics.
We report on the synthesis and characterization of highly monodisperse amorphous silica nanoparticles (ASNs) and mesoporous silica nanoparticles (MSNs) with particle sizes of 15–60 nm. We demonstrate adsorption of Cr(VI) ions on amino-functionalized ASNs (NH2–ASNs) and MSNs (NH2–MSNs) and their removal from aqueous environments and show the specific surface area (SSA) of NH2–MSNs is four times as larger as that of NH2–ASNs and that more than 70% of the total SSA of NH2–MSNs is due to the presence of nanopores. Analyses of Cr(VI) adsorption kinetics on NH2–ASNs and NH2–MSNs exhibited relatively rapid adsorption behavior following pseudo-second order kinetics as determined by nonlinear fitting. NH2–ASNs and NH2–MSNs exhibited significantly higher Cr(VI) adsorption capacities of 34.0 and 42.2 mg·g−1 and removal efficiencies of 61.9 and 76.8% than those of unfunctionalized ASNs and MSNs, respectively. The Langmuir model resulted in best fits to the adsorption isotherms of NH2–ASNs and NH2–MSNs. The adsorption of Cr(VI) on NH2–ASNs and NH2–MSNs was an endothermic and spontaneous process according to the thermodynamic analyses of temperature-dependent adsorption isotherms. The removal efficiencies of NH2–ASNs and NH2–MSNs exhibited a moderate reduction of less than 25% of the maximum values after five regeneration cycles. Furthermore, NH2–MSNs were also found to reduce adsorbed Cr(VI) into less harmful Cr(III).
In the industry, sodium carbonate is used to prepare sodium silicate; however, this process generates great volumes of CO 2 . In this work, sodium hydroxide has been proposed to prepare sodium silicate using natural sand. Two experimental variables were considered, sodium hydroxide concentration and temperature to prepare sodium silicate. Results show the formation of sodium silicate with a NaOH:sand ratio = 1.1 at 550 °C. Moreover, an economical revision was achieved to compare costs of sodium silicate with sodium hydroxide and sodium carbonate. The use of sodium hydroxide permits to decrease CO 2 emissions generated in the decomposition of sodium carbonate. Additionally, the sodium silicate prepared herein was used to synthesize a zeolite type material, SBA-15. SBA-15 obtained has similar characteristics than the commercial mesoporous material. The use of sodium silicate prepared with non-pure sand for preparing mesoporous materials is an economical and friendly environmental alternative.
Microporous NaY zeolite is a common support of Cu catalysts for oxidative carbonylation of methanol, but the dispersion of Cu species on NaY is usually subjected to its micropore size. Here, ordered mesoporous KIT‐6 was employed as the support for Cu catalyst and Al was incorporated into its framework to increase the surface acidity, which eventually improves the surface exchange capacity and Cu dispersion. The evolution of the state of Cu species on KIT‐6 was analyzed combined with control of Cu loading. The physicochemical properties of the supports and corresponding catalysts were characterized by N2 adsorption–desorption, X‐ray diffraction, ammonia temperature programmed desorption, Fourier transform infrared spectra, transmission electron microscopy, hydrogen temperature programmed reduction, and X‐ray photoelectron spectroscopy. It was found that mesoporous KIT‐6 showed better Cu dispersion than microporous NaY zeolite. Agglomerated CuO, dispersed CuO, and Cu²⁺ are the major Cu species observed on the catalyst surface. The increased surface acidic sites of KIT‐6 by Al incorporation promoted the formation of Cu²⁺ and dispersion of CuO. With the increase in Cu loading, the Cu²⁺ content in the catalyst was decreased gradually along with increase in the bulk CuO. It was speculated that some exchanged Cu²⁺ could be transformed into highly dispersed CuO and even bulk CuO after calcination at a high Cu loading. Combined with the catalyst evaluation results, it was deduced that highly dispersed Cu²⁺ and CuO particles play significant roles in catalytic activity. The catalyst Cu/Al‐K‐10 achieved the highest space time yield of dimethyl carbonate of 135.4 mg/(g·h), which is 2.7 times the Cu/K‐10 owing to its more dispersed Cu species. This laid the basis for preparing highly dispersed Cu species on mesoporous silica supports.
Coconut (Cocos nucifera) shell was chemically treated with sulfuric acid (H2SO4) to produce acid- factionalized biosorbent for methylene blue (MB) dye removal from aqueous environment. Various analytical techniques were utilized to investigate the surface area, surface morphology, crystallinity, elemental composition, and functional group of the sulfuric acid-treated coconut shell (SATCS). The adsorption parameters such as adsorbent dosage (0.02–0.20 g), solution pH (3–10), contact time (0–360 min), and initial MB dye concentration (25–200 mg/L) were studied. The adsorption results were illustrated by pseudo-second order kinetic and Freundlich isotherm models. It was found that SATCS has a maximum adsorption capacity (qmax) of 50.6 mg/g at 303 K. The adsorption mechanism of MB dye on the SATCS surface can be assigned to the various types of interactions such as electrostatic attractions, H-bonding interaction, and π-π interaction. This work shows SATCS as promising acid- factionalized biosorbent for removal MB dye.
For the immobilization of Candida rugosa lipase (CRL), mesoporous silica (SBA-15) was synthesized using pluronic acid (P123) as template and cetyltrimethyl ammonium bromide as co-surfactant. Physical adsorption technique was employed to immobilize CRL over SBA-15 and the maximum enzyme adsorp-tion (300 mg g À1) was observed at pH 3. The scanning electron microscopy as well as FTIR analysis of the solid bio catalyst indicate the enzyme immobilization over the SBA surface. The solid bio-catalyst thus obtained was employed as solid biocatalyst for the transesterification of cotton seed oil with methanol to produce fatty acid methyl esters. The reaction was found to follow the pseudo-first order reaction rate law and rate constant and activation energy for the reaction was evaluated to be 9.6 Â 10-4 min À1 and 57 kJ mol À1 , respectively.
In this research work, a new magnetic Schiff's base-chitosan-Benzil/zinc oxide/Fe3O4 nanocomposite (Cs-Bz/ZnO/Fe3O4) was developed to be a promising and recoverable bioadsorbent for Remazol Brilliant Blue R dye (RBBR) removal from the aquatic environment. Parametric optimization by Box–Behnken design was made to optimize the synthesis condition (loading ZnO nanoparticles into polymeric matrix of Cs) in addition to adsorption operation parameters (adsorbent dose, solution pH, temperature, and contact time). The obtained results show that the fast RBBR removal (98.8%) can be achieved by loading 25% ZnO nanoparticles into polymeric matrix of Cs (Cs-Bz/ZnO-25/Fe3O4), and at optimum adsorption operation parameters (adsorbent dosage of 0.04 g, solution of pH 4, temperature of 60 °C, and contact time of 10 min). At these optimum conditions, the maximum adsorption capacity was found to be 620.5 mg/g. The best isotherm and kinetic models were Freundlich model and pseudo-second-order kinetic model, respectively. The probable RBBR dye adsorption mechanism can be assigned to various types of physicochemical interactions (i.e; electrostatic, n-π, π-π interactions) in addition to hydrogen bonding and Yoshida H-bonding. The output of this research confirms that Cs-Bz/ZnO-25/Fe3O4 is a superior, recoverable, and environment friendly biohybrid nanocomposite adsorbent. The remarkable output of this research can open a window for other possible significant applications such as tenement of real waste water, removal of heavy metal ions, and reduction of chemical oxygen demand.
In this work, Schiff's base magnetic crosslinked chitosan-glyoxal/Fe3O4 composite (CS-G/Fe3O4) was synthesized and further developed by loading zinc oxide (ZnO) nanoparticles into its polymeric matrix. The final composite material of magnetic crosslinked chitosan-glyoxal/ZnO/Fe3O4 nanoparticles (CS-G/ZnO/Fe3O4 NPs) was tested for the removal of organic dye pollutant (reactive blue 19, RB19). The synthesized magnetic nanomaterials were characterized by several techniques such as CHN elemental analysis, Brunauer-Emmett-Teller analysis, vibrating-sample magnetometer, X–ray powder diffractometry, Fourier Transforms infrared, scanning electron microscope, energy dispersive X-Ray analysis, pHpzc, and pH-potentiometric titrations. A statistical approach namely Box–Behnken design (BBD) was applied to optimize the synthesis conditions as well as adsorption key parameters (A: ZnO nanoparticles loading (0–50%), B: adsorbent dosage (0.02–0.1 g), C: pH (4–10), D: temperature (30–60 °C), and time E: (10–60 min)). The adsorption kinetic and equilibrium results were well described with pseudo-second order model and Freundlich isotherm model, respectively. The maximum adsorption capacity of CS-G/ZnO/Fe3O4 NPs for RB19 was 363.3 mg/g at 60 °C. The adsorption mechanism of RB19 onto CS-G/ZnO/Fe3O4 NPs can be ascribed to several types of interactions (e.g. electrostatic attractions, hydrogen bonding, and n-π interactions). This study provides a new and effective adsorbent for water remediation due to its recoverability and high efficiency in removing the organic dye pollutants.
Two isostructural metal–organic frameworks (MOFs) were tested as adsorbent materials in matrix solid-phase dispersion (MSPD) for the extraction of lindane, bifenthrin, and pirimicarb from freeze-dried chicken eggs (Gallus gallus domesticus). A validated methodology (1.5 g of Florisil® as dispersant, cleanup with 0.5 g of C18, and 10 mL of acetonitrile as eluent) was used to evaluate the performance of the new materials. Analyses were performed by gas chromatography-mass spectrometry in select ion monitoring mode. Analytical curves (0.01–2 µg mL−1) showed good linearity (correlation coefficient R2 > 0.999). Extraction tests at one concentration level (1.25 µg g−1, n = 3) showed acceptable recovery results according to the literature (%recovery [REC] between 70 and 120%): (1) ∞[(Nd0.9Eu0.1)2(DPA)3(H2O)3] (%REC = 77–90%); (2) ∞[(La0.9Eu0.1)2(DPA)3(H2O)3] (%REC = 78–91%), and (3) Florisil® (%REC = 85–102%), with relative standard deviations (%RSD) of 1.1–3.8%, 3.7–7.9%, and 0.8–3.9%, respectively. The MOF materials presented satisfactory results when compared to conventional material. Furthermore, the amount of adsorbent could be reduced (0.5 g) compared to the original method. The application of the new materials as pesticide adsorbents in MSPD on a fatty biological sample was efficient.
Increasing demand for renewable chemicals and fuels has stimulated the search for alternative feedstocks and is driving the ongoing transition to a more renewables-based society. Considerable academic efforts have been directed at the valorisation of biomass sources and derived intermediates, so called platform molecules, to produce value-added chemicals and fuels. In this contribution, opportunities are discussed for the application of zeolite-supported bifunctional catalysts in the conversion of biomass sources into chemicals and fuels via hydrodeoxygenation (HDO). Such metal/zeolite catalyst systems play a prominent role in many of these biomass HDO routes. Emphasis is put on the current progress in metal/zeolite-catalysed HDO of three selected, promising routes involving biomass-derived platform molecules and the model compounds that mimic more complex feeds. Four key concepts of metal/zeolite catalysts, such as combining metal and Brønsted acid sites, site-ratio balancing, proximity between metal and acid functions and shape selectivity are discussed in order to provide a comprehensive overview. In addition, two challenges related to the accessibility of the active sites and catalyst stability in the liquid phase, typically a hot, highly polar, and protic reaction medium, are discussed. Finally, the open challenges and perspectives regarding the development of metal/zeolite catalysts for biomass HDO reactions are examined.
Flupentixol (FPL) – a antidepressant drug and an emerging micropollutant was taken as model pharmaceutical pollutant in this study. Graphene oxide (GO) nanoparticles were synthesized via chemical oxidation cum exfoliation, composited with cellulose (GOC) and utilized for FPL adsorption from aqueous medium. Batch adsorption of FPL onto GO or GOC was carried out in a Box-Behnken based design with a parameter set of pH (4.5, 6.5 and 8.5), adsorbent dosage (50, 100 and 150 mg/L), initial concentration (30, 50 and 70 mg/L), and solution temperature (15, 30, 45 °C). Particle swarm optimization (PSO) algorithm based artificial neural network (ANN) model was developed to optimize the adsorption process parameters. FPL adsorption onto GO and GOC was chemisorption followed by pore diffusion, exothermic, and spontaneous in nature. The molecular docking simulation of FPL and GO visualized the hydrogen bonding, hydrophobic interactions, π−π interactions, sulphur interaction, and lone pair interactions occurred during adsorptive removal of FPL using GO adsorbent.
In current research work, chitosan (Chi) was subjected to subsequent physical and chemical modifications by incorporating kaolin clay (KA) into its polymeric structure, and crosslinking process with a covalent cross-linker namely epichlorohydrin (ECH) respectively. The final product of crosslinked chitosan-epichlorohydrin/kaolin (Chi-ECH/KA) composite was successfully applied for color removal and chemical oxygen demand (COD) reduction of textile dye namely reactive blue 19 dye (RB19) from aqueous environment. The influence of pertinent parameters, i.e. A: Chi-ECH/KA dose (0.02–0.1 g), B: pH (4–10), and C: time (5–30 min) on the RB19 color removal and COD reduction were statistically optimized by using response surface methodology with Box–Behnken design (RSM-BBD). The experimental data of the adsorption kinetic and isotherm adsorption demonstrate a better fitness to pseudo-second order model and Langmuir isotherm model respectively. Excellent absorption ability of 560.9 mg/g was recorded for Chi-ECH/KA composite. The calculated thermodynamic functions clarified that the RB19 adsorption process was endothermic and spontaneous in nature. The mechanism of RB19 adsorption onto the Chi-ECH/KA may include electrostatic interactions, hydrogen bonding, Yoshida H-bonding, and n-π interactions. This study introduces Chi-ECH/KA composite as an eco-friendly, potential and multi-function composite bio adsorbent for removal of textile dye and COD reduction from aqueous environment.
The synthesis of nano-architectured mesoporous materials is of great importance for the sciences of multifunctional materials, since the textural and structural features of mesoporous silicas allows its application in the most different areas of technological knowledge. In view of growing interest of the scientific community in the use of silica-based mesoporous materials, as well as the environmental concern of obtaining advanced materials through increasingly cleaner, low-cost, and eco-friendly processes, this review aims to give an overview in the literature of main alternative silica sources that have been used to synthetize the silica-based mesoporous arrays. Also, we present what are the main applications of these mesoparticles. We can highlight that the main mesoporous materials studied in the literature are those of the M41S, SBA-n, FDU-n, and KIT-n families, which presented well-structured silica-based mesoporous materials with different pore geometries and architectures. Thus, allowing the application of these architectured materials in different scientific areas. The synthesis of silicon-based mesoporous materials has been increasingly sought from the use of low-cost and eco-friendly silica sources from the reuse of industrial wastes, in an attempt to minimize the possible impacts on the environment and human health of inadequate disposal of these wastes. Based on our literature review, the main alternative silica sources that are being used for the synthesis of silica-based mesoporous materials are rice hush ash, wheat husk ash, palm oil fuel ash, Miscanthus ash, e-waste, coal ash, reed ash, sedge ash, Carex riparia, sugarcane ash, bamboo leaf ash, natural clay, ore tailing, and others.
In this research, sulfuric acid (H2SO4, SA) treated Malaysian low rank namely Merit Kapit coal (MKC) for developing acidic-rich group adsorbent for decolourization and chemical oxygen demand (COD) reduction of cationic dye (Methylene blue dye; MB) from aqueous environment. The physicochemical properties of the sulfuric acid-treated Merit Kapit coal (SAMKC) such as morphological aspect, material crystallinity, surface area, surface functional groups, and elemental composition were investigated. The effect of the key adsorption parameters such as A: SAMKC dose, B: solution pH, C: temperature, and D: contact time on decolourization and chemical oxygen demand (COD) reduction of MB dye were statistically optimized using Box–Behnken design. The adsorption isotherm at equilibrium was well-described by the Freundlich model. The optimum BBD output for MB decolourization (78.5 %) and COD reduction (63.3%) were recorded at 0.1 g SAMKC dose, solution pH 10, temperature 40 °C, and contact time 37.5 minutes. At these optimum conditions, the best SAMKC adsorption capacity (421.1 mg/g) for MB dye was recorded at 40 °C. Varity of possible interactions (electrostatic, π-π, and H-bonding) were the main reason for capturing MB dye molecules on the surface of SAMKC. The findings of this work show the feasibility MKC to be a promising precursor for the producing an effective adsorbent with potential application for cationic dye removal from aqueous environment.
With the purpose to compete with the homogeneous catalytic biodiesel production, a highly efficient bimetallic solid catalyst with high exposed surface, high basicity, and reusable throughout several reaction cycles, was developed by doping SBA-15 with sodium and cerium in different concentrations. The catalyst with 5 wt% of sodium and 20 wt% of cerium showed good structural ordering and had the highest basicity due to the presence of a large amount of medium and strong sites compared to the other materials. It was effectively used as a solid base catalyst for biodiesel production from sunflower oil and absolute methanol. The highest FAME content (98.9 wt%) was achieved under optimum conditions of 40:1 methanol/oil molar ratio, 10 wt% catalyst loading, 60 °C, stirring speed of 600-700 rpm and 180 min. Further, this material was reused for five consecutive runs, obtaining FAME contents greater than 90% in each one of them.
Mesoporous TiO₂ films are synthesized through evaporation-induced self-assembly using poly(ethylene oxide-b-ε-caprolactone) diblock copolymers as a soft-template. Using small-angle X-ray scattering and scanning electron microscopy, we investigate the effect of the TiO₂/PEO-b-PCL ratio on the resulting nanoarchitectonic structure. After sputter-coating Au and Pt layers, these Au/TiO₂ and Pt/TiO₂ nanocomposite films display drastically enhanced photodegradation of rhodamine 6G under ultraviolet irradiation, due to the metal films inhibiting the rapid recombination of photogenerated charge carriers.
Bamboo chip (BC) biomass was used as an alternative precursor for producing high surface area and mesoporous bamboo chip activated carbon using KOH activation with pyrolysis process. Various characterization methods were employed to study the morphological characteristics, material crystallinity, surface area property, elemental composition, and surface functional group of the bamboo chip activated carbon (BCAC). The Brunauer–Emmett–Teller analysis showed that the bamboo chip activated carbon has a high surface area (720.69 m2/g) and mesoporous structure (mean pore diameter 7.32 nm). The adsorption property of bamboo chip activated carbon for the removal of methylene blue (MB) from aqueous media was evaluated. The effect of key adsorption parameters such as the bamboo chip activated carbon dose (A: 0.02–0.1 g/L), pH (B: 3–10), temperature (C: 30–50 °C), and time (D: 5–20 min) was optimized using a response surface methodology–Box–Behnken design. The kinetics of adsorption obeyed a pseudo-first order. The adsorption equilibrium was well described by the Freundlich isotherm model. The maximum adsorption capacity (qm) of MB dye was found to be 305.3 mg/g at 40 °C. The MB dye adsorption mechanism onto bamboo chip activated carbon surface indicates various dye–adsorbent interactions: electrostatic attraction, π–π interaction, and H-bonding. This study demonstrates the utility of bamboo chip as a biomass precursor for the efficient synthesis of activated carbon with favorable cationic dye adsorption properties.
Pt/CeO2-ZrO2-Fe2O3/SBA-16 (SBA-16: Santa Barbara Amorphous No. 16) catalysts were prepared to produce glyceraldehyde (GLA) from glycerol effectively at around room temperature in an open air system. By introducing Fe³⁺ ion into CeO2-ZrO2, the oxygen release and storage abilities were improved, which led to the high oxidation ability of Pt. The highest activity was obtained for 6.7wt%Pt/15.3wt%Ce0.64Zr0.15Fe0.21O2−δ/SBA-16, and the GLA yield reached up to 22.1% under the moderate condition of 30 °C for 4 h in an open air atmosphere.
The facile synthesis of crosslinked chitosan-tripolyphosphate/kaolin clay (CS-TPP/KC) composite was performed by two subsequent steps involving modification of chitosan (CS) with an inorganic clay (kaolin, KC), followed by ionic cross-linking reaction by tripolyphosphat (TPP). The applicability of the CS-TPP/KC composite for decolourization and chemical oxygen demand (COD) reduction of remazol brilliant blue R dye (RBBR) from aquatic system was investigated. The main key factors that influences the RBBR dye decolourization and COD reduction such as A: CS-TPP/KC dosage (0.02-0.1 g), B: pH (4-10), and C: time (5-30 min) were optimized by using Box–Behnken design (BBD). The highest RBBR dye decolourization (99.5%) and COD reduction (88.5%) were observed at the following significant interactions: AB, BC, and AC (only on COD reduction was significant). Langmuir isotherm was the best model presented the adsorption process with remarkable adsorption capacity of 687.2 mg/g was obtained for CS-TPP/KC composite at 30 ˚C. This work highlights that CS-TPP/KC composite offers great potential as a low-cost and effective biocomposite material for the organic dyes removal and COD reduction from water/ wastewater.
For the immobilization of Candida rugosa lipase (CRL), mesoporous silica (SBA-15) was synthesized using pluronic acid (P123) as template and cetyltrimethyl ammonium bromide as co-surfactant. Physical adsorption technique was employed to immobilize CRL over SBA-15 and the maximum enzyme adsorption (300 mg g⁻¹) was observed at pH 3. The scanning electron microscopy as well as FTIR analysis of the solid bio catalyst indicate the enzyme immobilization over the SBA surface. The solid bio-catalyst thus obtained was employed as solid biocatalyst for the transesterification of cotton seed oil with methanol to produce fatty acid methyl esters. The reaction was found to follow the pseudo-first order reaction rate law and rate constant and activation energy for the reaction was evaluated to be 9.6 × 10⁻⁴ min⁻¹ and 57 kJ mol⁻¹, respectively.
Hydrophobic and hydrophilic silver-functionalized SBA-15 silica nanocomposites were prepared via direct synthesis using the so-called BOTTOM-UP approach to nanotechnology. This process enables silica-based nanocomposites with a controlled metal content to be fabricated. XRD, XPS, Raman, SEM-EDX and TEM methods were used to describe the physicochemical properties of these systems. The surface atomic content of silver (XPS) was estimated at approximately 0.03 at.% and 0.04 at.% compared to the bulk signal (SEM-EDX), which was determined to be about 0.33 at.% and 0.48 at.%, respectively for the non-silylated and silylated systems. The XPS studies that were carried out for these two structures revealed the presence of elemental and/or oxidized silver on the surfaces. However, in the more volumetric XRD studies, there was no clear signal that corresponded to this metal, which suggests the presence of an ionic form of silver. Calcination was used to obtain the silver-decorated porous silica ceramic composites, for which the calcination temperature was determined from TGA/DTG studies. The calcination resulted in the compensation of the surface and bulk atomic content of silver at approximately 0.1 at.% (on both the surface and the bulk). The wettability measurements classified silylated specimens as well as silylated and calcined systems as being hydrophilic and hydrophobic, respectively. Low-angle diffraction confirmed the mesoporous character of the silica with hexagonal pore channels regardless of the degree of functionalization or calcination. The Raman data illustrated the impact of the silver on the propyl-carbonate chains and silica structure. Finally, the most vigorous bactericidal activity was found against Staphylococcus aureus and Escherichia coli for a hydrophilic system with a low silver content and a calcined sample with a slightly higher silver concentration.
In the process of synthesis of a new drug, as important as the drug itself is the formulation used, because the same compound can present a very different efficacy depending on how it is administered. In this work, we demonstrate how the antitumor capacity of a new octahedral organoruthenium complex, [Ru(ppy-CHO)(phen)2][PF6] is affected by its encapsulation in different types of mesoporous silica nanoparticles. The interactions between the Ru complex and the silica matrix and how these interactions are affected at two different pHs (7.4 and 5.4, mimicking physiological and endolysosomal acidic conditions, respectively) have been studied. The encapsulation has also been shown to affect the induction of apoptosis and necrosis and progression of the cell cycle compared to the free drug. The encapsulation of the Ru complex in nanoparticles functionalized with amino groups produced very high anticancer activity in cancer cells in vitro, especially against U87 glioblastoma cells, favoring cellular internalization and significantly increasing the anticancer capacity of the initial non-encapsulated Ru complex.
Silica SBA-16, an efficient photocatalyst support with cubic (bottle-ink) mesoporous structure, large specific surface area, large pore volume and uniform pore size and titanium oxide (TiO2), a semiconductor compound as the active site were synthesized facilely via one-pot method and photocatalysts denoted as x%TiO2/SBA-16 where x = 2, 5, 10 and 20, in order to examine their photocatalytic ability for phenol degradation in different experimental conditions such as different phenol concentration in water (ppm), various pH of the solution and amount of applied photocatalyst (g/l). In order to confirm the correct structure of the SBA-16 support and prepared photocatalysts, various types of characterization analyses such as N2 adsorption/desorption, X-ray diffraction (XRD), TEM, SEM–EDX, UV–VIS and FT-IR were applied. Based on the employed analyses, it can be claimed that the SBA-16 support and synthesized photocatalysts demonstrated mesoporous structures with cubic pores that are in agreement with reliable literature. After carrying out all of the experimental factors for the phenol degradation process, it was found that the 10%TiO2/SBA-16 photocatalyst in the specific experimental conditions including pH 7, phenol concentration of 100 ppm and 1 g/l photocatalyst dosage achieved the highest performance which was approximately 90% degradation of phenol. Hence these mentioned conditions were chosen as the optimum experimental conditions. COD and TOC tests were employed to study the final products of the process and their results showed that the 10%TiO2/SBA-16 photocatalyst was able to reduce the COD and TOC of phenol solution up to 80% and 85%, respectively, means that the major amount of phenol converted to water and CO2 that are the final products of phenol degradation process.
A new technology based on high gravity coupled nanofluids intensification mass transfer technology for efficiently capture CO2 was adopted in this work. It can overcome the mass transfer limitation of CO2 and enhance the capture effect. The nanoparticles MCM-41 was synthesized from coal fly ash and functionalized with (3-aminopropyl) triethoxysilane. The nanoparticles NH2-MCM-41 was dispersed in diethylenetriamine (DETA) by ultrasonic dispersion method. XRD, SEM, FTIR, N2 adsorption-desorption and TG were used to characterize the physicochemical properties of NH2-MCM-41 materials. Experimental results suggested that the existence of NH2-MCM-41 nanoparticles in DETA solution could effectively improve CO2 capture. The optimum conditions were the high gravity factor of 48.09, liquid-gas ratio of 0.07 and NH2-MCM-41 dosage of 0.1wt%. Compared with the results of using DETA solution without adding NH2-MCM-41, CO2 capture efficiency was improved by 4.7% due to the enhancement of grazing effect and hydrodynamic effect in the high gravity environment. The combination of the two process intensification technologies reduces the mass transfer resistance, strengthens the mass transfer process of CO2 and enhances the CO2 capture effect. This work might offer a promising and green approach for production of MCM-41 to capture CO2 by combing high gravity technology. Turning coal fly ash into treasure, harm into profit, realizing waste control waste and green environmental protection.
The Al-doped mesoporous crystalline material-41 (Al-MCM-41) composite was prepared and applied as fiber coating material of headspace solid-phase microextraction (HS-SPME) for extraction of polycyclic aromatic hydrocarbons (PAHs) from human urine. Five PAHs including acenaphthene, fluorene, phenanthrene, anthracene, and pyrene are chosen as target analytes to evaluate the performance of the material by GC-FID analysis. The mesoporous Al-MCM-41 composite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption/desorption measurement, and thermogravimetric analysis. The parameters affecting the extraction efficiency of HS-SPME were investigated. Under the optimal conditions, the method exhibits ideal linearity for target analytes in the range of 0.3–600 ng⋅mL⁻¹ with the coefficients (R²) equal or higher than 0.9906. The enrichment factors are calculated from 540 to 1760. The limits of detection (LODs) and limits of quantitation (LOQs) are between the ranges of 0.06–0.18 and 0.3–0.9 ng⋅mL⁻¹, respectively. The relative standard deviations (RSDs) (n = 5) of intra-day and inter-day are in the ranges of 1.08–7.49% and 2.84–18.3% respectively. The fiber-to-fiber reproducibility (n = 3) is in the range of 6.47–13.9%. The method was successfully applied for the analysis of PAHs in human urine with reasonable recoveries which is ranging from 73.29 to 116.1%.
Chitosan/MCM-48 (CH/MCM) and β-cyclodextrin/MCM-48 (CD/MCM) composites were synthesized as promising and eco-friendly bio-adsorbents for Cd2+ ions from water. The composites showed novel porous structures and complex functional groups making them of high adsorption capacities. The adsorption behaviors of CH/MCM and CD/MCM are highly controlled by the tested pH values realizing their best capacities at pH 7. The kinetic evaluation indicated the excellent agreement between the uptake of Cd2+ by CH/MCM and CD/MCM with the pseudo-first-order model achieving equilibrium intervals of 480 min and 600 min, respectively. Based on the values of Chi-squared (X2) and the correlation coefficient, the composites displayed adsorption properties related to the Freundlich hypothesis with a multilayer form. Additionally, the Gaussian energies of them are 2.23 KJ/mol (CH/MCM) and 2.46 KJ/mol (CD/MCM) reflecting physical uptake of Cd2+ by the studied composites. The thermodynamic investigation implied spontaneous uptake of Cd2+ by the composites with endothermic reactions. The prepared CH/MCM and CD/MCM are of 122.4 mg/g and 152.2 mg/g theoretical qmax, respectively which are higher values than the reported results for several studied adsorbents. Moreover, the synthetic CH/MCM and CD/MCM showed high reusability as adsorbents for Cd2+ to be applied effectively six times
In this study, quaternized salicylaldehyde Schiff base modified SBA-15 mesoporous silica (SBA-AP) was developed. The characterization of SBA-AP shows that the Schiff base ligand has been successfully introduced and ordered mesoporous structure of SBA-15 has been well-preserved after the post-grafting procedure. The quaternized linkage made the as-prepared nanohybrid very dispersible in water, and the salicylaldehyde Schiff base acted as a multifunctional ligand for complexing Cu(II). By adding Cu(II) into the SBA-AP suspension, the absorbance UV intensity at ∼420 nm gradually increased. In addition, the adding Cu(II) caused dramatic fluorescence quenching that was very selective for Cu(II) ions. The linear detection range for the Cu(II) chemosensor was 0.05–4 mg/L, and the detection limit was 3.7×10⁻⁷ M. The SBA-AP could also be used as an adsorbent for removing Cu((II) from water. The adsorption kinetics were fast and followed the pseudo-second-order kinetics model. The adsorption isotherms were fitted well by Langmuir isotherm mode and theoretical maximum Langmuir adsorption capacity of the SBA-AP toward Cu(II) was 34.73 mg/g. Thus, the SBA-AP offers promise for detecting, adsorbing, and recovering Cu(II) ions from water.