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Modification of kaolinite from Pará/Brazil region applied in the anionic dye photocatalytic discoloration
摘要： The incorporation of titanium oxide and other transition metals on the surface of different materials has been shown to be a promising strategy to improve the efficiency of photocatalytic processes aiming at the decontamination of aqueous systems caused by persistent organic contaminants such as dyes. The objective of this work was to evaluate the catalytic properties of nanocomposites based on the kaolinite (Kaol) with TiO2 incorporated, obtained from the sol-gel method, used in discoloration of the coomasie brilliant blue dye (CBB) in aqueous solution. The nanocomposites were prepared from the reaction of titanium tetraisopropoxide with purified natural kaolinite and calcined at different temperatures. The samples were characterized by the XRD, FTIR, SEM-XED, BET-BJH and diffuse reflectance spectroscopy techniques, which demonstrated the structure, crystalline pattern, as well as the incorporation of titanium in the clay structure, changes caused by modification in morphology, texture and energy gap. The photocatalytic tests were performed using 5 × 10?5 mol L?1, 1.0 and 1.5 g L?1 concentration, respectively, to the CBB dye solution and to the synthesized materials. Among the nanocomposites, the sample calcined at 300 °C, KaolBT-300, presented the best photocatalytic performance. The addition of the H2O2 oxidant to the solution containing KaolBT-300 at the concentration of 1.5 g L?1 increased the discoloration percentage to 97.31% of the CBB solution dye after 120 min of irradiation. The discoloration kinetics of the CBB dye obeys the pseudo-first-order velocity law. Finally, the reuse of the KaolBT-300 sample in three consecutive cycles of photocatalysis demonstrated a significant adhesion stability of the TiO2 particles on the clay surface, indicating that it can be used in advanced oxidative processes for the degradation of organic pollutants.
关键词： Natural clay,Sol-gel synthesis,Heterogeneous catalysis,Titanium oxide,Water treatment,Dye
更新于2025-09-10 09:29:36
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Modifications in structural, optical and electrical properties of nanocrystalline CdO: role of sintering temperature
摘要： Present report deals with the synthesis of nanocrystalline cadmium oxide (CdO) using low-cost acetate precursor based modified sol–gel technique. Final product was sintered at different temperatures and studied for their structural, optical and electrical properties. In this present work, we report the sintering temperature-dependent structural, optical and electrical properties of nanocrystalline cadmium oxide (CdO) grown by cost effective sol–gel method. Structural properties of CdO materials were investigated by X–ray diffraction (XRD) which reveals the crystalline phase of the samples without any detectable impurity within the range of measurements. Crystallite size (CS), calculated using Scherer’s formula, is found in the range of nanometer (<100 nm) and increases with increasing sintering temperature. Average crystallite size of all CdO nanocrystals were estimated using the William–Hall (W–H) plots from XRD patterns. Furthermore, transmission electron microscopy (TEM) images were captured to check the crystallinity and particle growth of the samples. The optical properties of nanocrystalline CdO were studied by using UV–Visible (UV–Vis) absorption spectrum. High absorption has been observed for nanocrystalline CdO sintered at lower temperatures. The band gap of nanocrystalline CdO was calculated by using Tauc’s law where band gap increases with increasing sintering temperature. The electrical properties of the samples were studied by performing dielectric and AC conductivity measurements. It is observed that dielectric constant decreases with increase in frequency and sintering temperature. Variation in AC conductivity with light and sintering temperature has been discussed in detail.
关键词： Nanocrystalline,Photoconduction,Sol–gel synthesis,Sintering temperature
更新于2025-09-09 09:28:46
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[Polymers and Polymeric Composites: A Reference Series] Functional Polymers || Organic-Inorganic Hybrid Materials and Their Applications
摘要： The organic-inorganic composites in addition to providing new alternate materials represent a class that exhibit novel, astonishing features, and their properties can be tailored to suit a particular application. These are developed by combinations of two or more materials that differ in form or composition on a macroscale. The matrix and the filler are two indispensable components of a composite. In this chapter, synthetic routes, viz., sol-gel, blending, and emulsion polymerization, classification, and application of organic-inorganic composites as ion-selective membrane electrodes has been discussed. The ion-selective electrodes provide simple, reliable, low cost, on-spot methods for the detection of heavy metal ions. The field of hybrid materials is vast open and promising and newer possibilities to improve their application are to be explored.
关键词： Selectivity,Sol-gel synthesis,Composite,Ion-selective membrane electrode
更新于2025-09-09 09:28:46
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Role of water in the sol-gel synthesis of yttrium monosilicate
摘要： Yttrium monosilicate (YMS) is a candidate environmental barrier coating material.It is a line compound, and its synthesis requires strict stoichiometric control of the starting materials. In this work, YMS was synthesised by the sol-gel method. Yttrium oxide and tetraethyl orthosilicate (TEOS) were used as precursors. The ratio of water to ethanol was varied to study the role of water in the formation of phase-pureYMS. The formation of secondary phases during synthesis was attributed to the complex interaction of TEOS with water in the presence of ethanol. It was seen that water and ethanol play a significant role in aqueous sol-gel processes involving silica than merely being present as solvents. The results are helpful in identifying the suitable sol-gel parameters for the synthesis of phase-pure yttrium monosilicate.
关键词： Environmental barrier coatings (EBC),Sol-gel synthesis,yttrium monosilicate (YMS)
更新于2025-09-09 09:28:46
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Effect of polyethylene glycol and propyltrimethoxysilane on structural and optical properties of zinc oxide nanoparticles synthesized by sol–gel process
摘要： Zinc oxide nanoparticles (ZnO NPs) are prepared by sol–gel process, using both polyethylene glycol (PEG-400) as surfactant and propyltrimethoxysilane (PTMS) as capping agent. Surface modi?cation is performed in situ procedure. The physical parameters such as strain and stress values are calculated via the Williamson–Hall plot (W&H) assuming a uniform deformation model (UDM) and uniform stress deformation model, and by the size and strain plot method (SSP). The results show that the crystallite size estimated from Scherrer’s formula, (W&H), (UDM), (SSP) and the particle size estimated from DSL are inter-correlated, which con?rm the small size and the isotropic nature of our ZnO NPs. The FTIR spectroscopy illustrates that PEG-400 and PTMS could be adsorbed at the ZnO NPs surface. The distinct emission peak in the blue band is located at 490 nm and E2 (high) mode is situated at 436 cm-1. Both results con?rm the oxygen de?ciency in the ZnO NPs.
关键词： Propyltrimethoxysilane,Sol–gel synthesis,Zinc oxide,Nanoparticles,PEG-400,DRX
更新于2025-09-09 09:28:46
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Fabrication and analysis of the structural phase transition of ZrO <sub/>2</sub> nanoparticles using modified facile sol–gel route
摘要： The synthesis of zirconia nanoparticles is achieved through a modified facile sol–gel route. The as-prepared gel is analyzed thermally using TGA and DTA techniques to spot the crystallization process of zirconia nanoparticles. The prepared gel is then annealed at different temperatures and the structure was found to change between tetragonal and monoclinic crystal systems. The first stable tetragonal phase is achieved after annealing for 2 h at 400°C. The annealed powders between 600°C and 800°C demonstrate mixed tetragonal/monoclinic phases. Annealing at 1000°C and higher temperatures up to 1200°C resulted in pure monoclinic phase. Cubic phase was not detected within the annealing temperature range in this study. The elemental analysis of the annealed powder confirmed the formation of zirconia nanoparticles with the chemical formula ZrO2. The FTIR spectra of the annealed samples introduced a variation in the vibrational bands especially around the phase transition temperature. HR-TEM images reported the formation of nano-zirconia crystals with apparently large particle sizes. The optical energy gap of zirconia nanoparticles is investigated and determined.
关键词： ZrO2 nanoparticles,HR-TEM,sol–gel synthesis,EDAX,optical energy gap
更新于2025-09-09 09:28:46
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Effect of Tin and Strontium Doping on the Photocatalytic Activity of Zinc Sulphide Nanoparticles for the Photocatalytic Degradation of Resorcinol under Solar and Ultra-Violet Light
摘要： Tin (Sn) and Strontium (Sr) doped Zinc Sulphide and pure Zinc Sulphide photocatalyst have been prepared by Sol-Gel method. The prepared photocatalyst have been characterised by Thermo gravimetric Differential Thermal Analysis, Scanning Electron Microscopy, Energy Dispersive X-ray, X-Ray Diffraction, ultra-violet visible spectroscopy and photoluminescence spectroscopy. Characterization Techniques have provided information of wurtzite hexagonal structure of Zinc Sulphide. The PL spectra have shown the blue shift of Zinc Sulphide after doping it with Tin and Strontium. Photocatalytic degradation study was done by the complete degradation of an organic pollutant Resorcinol in Sun light as well as in UV-light. The factors affecting the photocatalytic activity of photocatalyst viz. pH, catalyst loading and reuse of photocatalyst have been studied along with the photocatalytic degradation of Resorcinol. These external parameters have considerable influenced on the phtocatalytic activity of Zinc Sulphide.
关键词： Photocatalyst,Pollution,Sol-gel synthesis,Doping,Zinc sulphide nanoparticles,Photoluminescence
更新于2025-09-04 15:30:14