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Commercial and Synthesized titanium di oxide (TiO2) prepared by conventional sol-gel method, are modified to degrade industrial dyes. Modification is done on bare TiO2 and TiO2 doped with various doping agents (activated charcoal/silicon dioxide/zinc oxide), followed by thermal treatments. The role of thermal treatments and doping effects on the ef...
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We report on the successful fabrication of multi-branched CuS nanodendrites with average branch length of about 20 nm by laser ablation of bulk Cu target in thioacetamide (TAA) solution. During the nucleation of Cu and S species, the accurate anisotropic growth should be attributed to an ultra-rapid acid etching process by laser-induced TAA hydroly...
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... The parabolic diffusion model (Eq. 14) was also tested to establish or reject the influence of diffusion on the photocatalyzed degradation of the BCGD [41]. The parabolic diffusion model plot (based on Eq. 14) for the photodegradation of BCGD is shown in Fig. 5d. ...
Contamination of water by dyes is prevalent in several industries and the application of some management strategies has compounded results such as the toxicity of the materials employed in the removal process. The present study seeks to degrade bromocresol green dye using calcium oxide nanoparticles (synthesized from gigas shells) as a photocatalyst. The catalyst was synthesized through a sol–gel process involving the conversion of the CaCO3 in the shells to CaO nanoparticles. The catalysts absorbed maximally at 306 nm and exhibited a band gap of 5.898 eV. The X-ray diffraction of the nanoparticle showed a major peak at 2θ = 29.40°, average crystallite size = 57.18 nm, d-spacing = 1.21 to 3.53 Å, density = 2.71 g/cm³, and cell volume = 3.807 × 10⁻⁴ pm³. Photodegradation experiments were conducted using the sun as a source of UV radiation, and results were obtained under variable conditions (such as variation in particle size, catalyst load, period of contact, ionic strength, pH) with percentage degradation efficiencies ranging from 68 to 89%. Best-fitted kinetic models for the photodegradation of the dye were the Langmuir–Hinshelwood, pseudo-second-order, and parabolic diffusion models. Regeneration of the catalyst recorded huge success with high re-use efficiency. Analysis of the band potentials toward redox degradation indicated that the valence band potential the (− 3.145 eV) is more negative than the potential of OH-/H2O(2.27V)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${OH}^{-}/{H}_{2}O (2.27 V)$$\end{document} while the conduction band potential (0.43 eV) is more positive than the potential of O2/O2-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${O}_{2}/{O}_{2}^{-}$$\end{document} (− 0.282 eV) which suggested that the degradation process was facilitated by superhydroxide. DFT data for the frontier molecular orbital energies of the dye were EHOMO = − 6.070 eV, ELUMO = − 2.560 eV, and energy gap = 3.71 eV. Adsorption is established to be a limiting factor in the photodegradation process and the evaluated adsorption energy (− 47.55 eV) confirmed that the initial mechanism of photocatalyzed degradation of the dye is spontaneous. Also, the HOMO–LUMO diagram and Fukui function calculations (at DFT/BLYP/6-31G*) gave evidence that supported the adsorption of the dye as a limiting factor in the photodegradation, which primarily involved superoxide and superhydroxide.
... However, these methods also have disadvantages; moreover, some of them do not have the ability to break down the dye completely. Therefore, photocatalysis is now thought to be one of the best ways to remove dyes from contaminated water [17]. Additionally, to overcome this issue, the photocatalytic process of various dyes degradation has shown to be a more efficient, cost-effective, and convenient way to eliminate abundant contaminants and organic pollutants from water. ...
Semiconductor titanium dioxide in its basic form or doped with metals and non-metals is being extensively used in wastewater treatment by photocatalysis due to its versatile nature. Other numerous characteristics including being environmentally friendly, non-pernicious, economical, multi-phase, highly hydrophilic, versatile physio-chemical features, chemical stability, suitable band gap, and corrosion-resistance, along with its low price make TiO2 the best candidate in the field of photocatalysis. Commercially, semiconductor and synthesized photocatalysts—which have been investigated for the last few decades owing to their wide band gap—and the doping of titania with p-block elements (non-metals) such as oxygen, sulfur, nitrogen, boron, carbon, phosphorus, and iodine enhances their photocatalytic efficiency under visible-light irradiation. This is because non-metals have a strong oxidizing ability. The key focus of this review is to discuss the various factors affecting the photocatalytic activity of non-metal-doped titania by decreasing its band gap. The working parameters discussed are the effect of pH, dyes concentration, photocatalyst’s size and structure, pollutants concentration and types, the surface area of photocatalysts, the effect of light intensity and irradiation time, catalyst loading, the effect of temperature, and doping impact, etc. The mechanism of the photocatalytic action of several non-metallic dopants of titanium dioxide and composites is a promising approach for the exploration of photocatalysis activity. The various selected synthesis methods for non-metallic-doped TiO2 have been reviewed in this study. Similarly, the effect of various conditions on the doping mode has been summarized in relation to several sorts of modified TiO2.
... Nanoparticles of metal oxide have attracted great attention in recent years because of their benefits in long-term programs of environmental remediation and digital devices. They have been broadly utilized in solar cells, piezoelectric nanogenerators, optoelectronic devices, UV detectors, photocatalysis, etc. due to their extended band gap, insolubility, and small sizes [11][12][13][14][15]. Titanium dioxide has been used as a photocatalytic due to its numerous advantages which consist of high chemical and optical stabilities, low charge and toxicity [16,17]. ...
In this work, highly-pure titanium dioxide nanoparticles produced by dc magnetron sputtering technique were embedded in coordination complex solutions such as Baq2 or Znq2 to form random gain media. The structural characteristics of the TiO2 nanoparticles were determined to confirm their high structural purity. The spectroscopic characteristics, mainly photoluminescence and fluorescence, of the complex solutions containing the nanoparticles were determined and studied. These media were compared to two of the most common laser dyes (Rhodamine B and Rhodamine 6G) to determine the feasibility of using them to produce random laser.
... Nanoparticles of metal oxide have attracted great attention in recent years because of their benefits in long-term programs of environmental remediation and digital devices. They have been broadly utilized in solar cells, piezoelectric nanogenerators, optoelectronic devices, UV detectors, photocatalysis, etc. due to their extended band gap, insolubility, and small sizes [11][12][13][14][15]. Titanium dioxide has been used as a photocatalytic due to its numerous advantages which consist of high chemical and optical stabilities, low charge and toxicity [16,17]. ...
In this work, highly-pure titanium dioxide nanoparticles produced by dc magnetron sputtering technique were embedded in coordination complex solutions such as Baq2 or Znq2 to form random gain media. The structural characteristics of the TiO2 nanoparticles were determined to confirm their high structural purity. The spectroscopic characteristics, mainly photoluminescence and fluorescence, of the complex solutions containing the nanoparticles were determined and studied. These media were compared to two of the most common laser dyes (Rhodamine B and Rhodamine 6G) to determine the feasibility of using them to produce random laser.
... Nanoparticles of metal oxide have attracted factors in present years because of their large ranging programs in environmental remediation and digital devices. They had been broadly utilized in solar cells, piezoelectric nanogenerators, optoelectronic devices, UV detectors, photocatalysis, etc. due to their extended bandgap, insolubility, and small sizes [18][19][20][21][22]. ...
In this work, highly-pure titanium dioxide nanoparticles produced by dc magnetron sputtering technique were embedded in organometallic complex solutions such as Baq 2 or Znq 2 to form random gain media. The structural characteristics of the TiO 2 nanoparticles were determined to confirm their high structural purity. The spectroscopic characteristics, mainly photoluminescence and fluorescence, of the complex solutions containing the nanoparticles were determined and studied. These media were compared to two of the most common laser dyes (Rhodamine b and Rhodamine 6G) to determine the feasibility to use them to produce random laser.
... A primary characteristic of Azoic dyes is the unique N = N chromophoric units whiles that of Xanthene is the yellow solid organic compound with the formula CH 2 [C 6 H 4 ] 2 O that is soluble in common organic solvents (Benkhaya et al., 2020). With the textile industry having about 60-70% usage of all available commercial dye products (Saggioro et al., 2011), the dye pollutants from these industries tend to contaminate the environment especially water bodies; when they are indecorously disposed-of (Habib et al., 2013;Rahman et al., 2014;Rezig & Hadjel, 2014). Furthermore, recent advances in environmental remediation strategies such as photocatalysis and flocculation have been researched as an alternative technique for purification of dye-polluted water Diko et al., 2020). ...
When organic dye-containing wastewater from textile industries are sometimes released into the environment, the liquids tend to pollute the environment whilst their solid residue accrues on land after the evaporation of the water. Most of these synthetic compounds are known to be poisonous and carcinogenic to living organisms. For this study, a relatively simple, sustainable and cost-effective approach have been utilized to synthesize CuO nanoparticles using copper precursor salts: (CuSO4.5H2O) and (Cu(NO3)2.3H2O), as a remedy for dye pollution reduction in water. Due to their simplicity of synthesis, insignificant harmfulness and cost, copper (II) oxide (CuO) nanoparticles were used to breakdown three generally utilized dyes; Rhodamine B (RhB), Methylene Blue (MB)- [Methylthioninium chloride] and Methyl Orange (MeO). The as-prepared nanoparticles were characterized to determine the ordered arrangement of atoms, functional groups, weight loss, thermal properties, microstructure and surface characteristics. Most significantly, the predominant preferential crystal growth was along the {002}/{-111} plane for the sulphate-based precursor whiles for the nitrate based precursor, it was preferentially grown along the {111} direction. The mesoporous nanoparticles had average crystallite sizes of 12 nm and 15 nm; and BET surface areas of 42.9 m2/g, and 69.6 m2/g respectively. The as-prepared nanoparticles were assessed for their photocatalytic behaviour in response to visible light exposure for 100 minutes at 25-min’ intervals. The nitrate precursor-based CuO photocatalysts showed relatively higher photodegradation efficiency (MeO-94.3%; MB- 90.6%; RhB - 99.6%) as compared with the sulphate precursor-based CuO photocatalysts (MeO-85.2 %; MB- 87.9%; RhB- 98.8%).
... Although clean water is important to society, these ongoing waste treatment processes tend to reduce the quality of water [1][2][3]. In particular, organic compounds such as dyes can contaminate the aqueous environment if not properly processed by textiles, paint, food, leather and paper industries [4][5][6][7]. Synthetic dyes have a wide range of uses which makes their use unavoidable. The only way to handle these dye contaminants is to develop safe disposal mechanisms and methods so that they can coexist with the ecosystem to provide a friendly environment. ...
In this research work, a simple method of silver nanoparticles’ self-synthesis in chitosan (CH) biopolymer hydrogels without utilizing a reducing agent is shown. The synthesized material was used as a catalyst in different reduction reactions. For this purpose, different amounts of CH powder were dissolved in acidic aqueous solutions and then crosslinked it with the formaldehyde solution to make a CH biopolymer hydrogel. Among all the prepared samples, a CH hydrogel prepared from a dense solution was found to be suitable for this study because of good mechanical stability. For the self-synthesis of silver nanoparticles inside hydrogel, it was immersed in an aqueous solution of AgNO3 (10 mM) for 3 days at room temperature. The color of the chitosan hydrogel changed to brown from transparent which indicated the successful formation of silver nanoparticles on CH hydrogel (Ag-CH). No reducing agent for conversion of the Ag1+ ions to nanoparticles in this whole synthesis method. Instrumental techniques such as FESEM, XRD and EDX analysis confirmed the successful preparation of Ag-CH. The Ag-CH was checked as a catalyst in the 2-nitrophenol (2-NP) and acridine orange (ArO) reduction reactions. Both reactions were carried out at high rate constants (2-NP = 0.260 min−1, ArO = 0.253 min−1) by using the Ag-CH hydrogel catalyst. In addition, we discussed the mechanism of action of the reducing agent, the effect of kapp on the two reduction reactions of Ag-CH and the recyclability.
... Metal oxide nanoparticles have attracted much interest in recent years due to their wide ranging applications in environmental remediation and electronic devices. They have been widely used in solar cells, gas sensing, piezoelectric nanogenerators, transparent conducting oxides, optoelectronic devices, UV detectors, photocatalysis, etc. because of their inherent properties like wide bandgap, insolubility, and comparatively small sizes [1][2][3][4][5]. To strengthen their properties according to necessity, several methods like tuning, doping with other metals and nonmetals, nanocomposite formation, preparation of metal oxide thin films have been introduced [6]. ...
The present study involves the successful synthesis of zinc oxide and tin oxide nanoparticles by green and chemical co-precipitation methods respectively. The synthesized samples were characterized by X-ray diffraction (XRD) and UV-visible absorption techniques. XRD analysis confirms the formation of hexagonal wurtzite structure of ZnO and pure cassiterite rutile tetragonal phase of SnO2. UV-visible spectroscopic study confirms the absorption of UV light by samples. The photocatalytic activities of both samples on Methylene blue (MB) and Malachite green (MG) dyes were analyzed and their corresponding kinetic modelings were studied. It is observed that SnO2 shows better degradation activity compared to ZnO.
... Synthetic dyes are produced over 7 × 10 5 tons annually in the world [1, 2] and widely used in textiles, paper, rubber, plastics, leather, cosmetics, tannery, painting, printing, laundry, pharmaceutical, and food industries [3]. It is estimated that about 1-20% of the total world production of dyes is lost during the dyeing process and is released in the textile effluents [4,5]. The removal of synthetic dyes from industrial wastes has been more noticeable than other colorless organic materials. ...
The present work studies the adsorptive removal of methylene blue (MB) dye from aqueous solution using a novel biocompatible adsorbent based on hydroxypropyl cellulose (HPC) and itaconic acid nanogels. The biocompatible adsorbent was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy and dynamic light scattering analyses. Response surface methodology was used to modeling and optimization of the adsorption process. A second-order empirical relationship between adsorption capacity and independent variables (pH of the solution, contact time and dye concentration) was obtained. The results of design of experiments demonstrated that the predicted values were well fitted with the experimental data where coefficient of determination (R²) equaled 0.9861. Pareto analysis for identification of the factors effect on the system revealed that the initial concentration of MB was the most effective parameter. Maximum removal efficiency (99.9%) was achieved at optimum parameters where pH, MB concentration, and contact time were 5.6, 130 mg L⁻¹, and 5 min, respectively. Furthermore, the adsorption experimental data were well fitted to the Temkin isotherm and pseudo-second-order kinetic model. Consequently, it was found out that the HPC–PIA nanogels with high adsorption capacity (nearly 761 mg g⁻¹) can be a suitable adsorbent for removal of cationic dyes from textile colored wastewaters.
... where q e and q t are the amounts of adsorbed Cr(VI) at equilibrium and at certain time t (min); k 1 (min À1 ) and k 2 (g mg À1 min À1 ) are the kinetic rate constants for the pseudo first-order and the pseudo second-order models, respectively, and for parabolic diffusion model, C o and C t are initial Cr(VI) concentration and concentration at t, respectively, k is kinetic constant, t is time of sampling and a is coefficient of parabolic model [27]. Evaluation on the kinetics equations are listed in Table 2. ...
Microwave-assisted synthesis of hydroxyapatite (HAp) from paddy field snail (Pila ampullacea) shell has been conducted. The synthesis was performed by producing CaO from snail shell using calcination method followed by wet preparation method with phosphoric acid. Microwave irradiation procedure was applied for the HAp formation. Physicochemical characterization of material was studied by X-ray diffraction (XRD) measurement, gas sorption analyzer, Fourier-Transform Infra-Red and also scanning electron microscope-energy dispersive X-ray and adsorption study for Cr(VI) in the form of bichromate ion. The XRD pattern shows that crystalline of HAp was obtained by both microwave irradiated method and reflux method with the similar properties as the material obtained from by CaO. Adsorption experiment showed the similar capability of prepared HAp. The kinetics of adsorption obeys pseudo second-order model. The adsorption isotherms are fit with Langmuir adsorption isotherms with the adsorption capacity of 23 and 21 mg g⁻¹ for HAp prepared by reflux and microwave irradiation methods, respectively.
