Papers by Keyword: Heterogeneous Photocatalysis

Abstract: The industry is one of the most polluting sectors of the aquatic ecosystem. Conventional treatment methods no longer have full effectiveness. The heterogeneous photocatalysis, using TiO₂ as the semiconductor (photocatalyst) is one of the most promising techniques for polishing industrial effluents. In the present study determines the best pH range, to optimize the phenomenon of adsorption, and evaluates the reduction of hexavalent chromium and the removal of organic matter in synthetic samples, using a reactor with glass plate impregnated with TiO₂ and making use of solar radiation. It was observed that the acidic pH is optimal for the photocatalytic process and that there was a minimum removal efficiency of 62% and 60% for Cr (VI) and organic matter, respectively.

Abstract: This work is dedicated to preparation and research of copper-containing solid-state mixed oxides based on F-doped titanium dioxide. All materials were prepared by hydrolysis of titanium tetraisopropoxide. NH₄F was used as F^‑ions source. Copper was introduced to the system in two ways: by impregnation from its copper nitrate and directly in the process of titanium dioxide synthesis. Microstructure, phase composition and surface area were studied by transmission electron microscope (TEM), X-ray diffraction (XRD) and low temperature nitrogen adsorption respectively. All materials have nanostructured porous structure and the majority of them contain only one TiO₂ phase – anatase. States of the elements were determined by X-ray photoelectron spectroscopy (XPS). Photoluminescence spectra (PL) show low intensity of photoluminescence for TiO₂ and F-TiO₂ samples and no photoluminescence for copper-containing samples. The absence of photoluminescence for copper-containing samples is associated with efficient charge transfer and separation.

Abstract: As automobile amount increasing, the atmosphere pollution for the automobile emission becomes very serious. In the paper, we have studied vehicle emissions of decontamination by using nanometer titanium dioxide of photocatalysis method in traffic environment. In the study phases, The test result indicated that degradation effect of nanometer titanium dioxide in road surface was well. It may be used in road traffic to protection environment.

Abstract: A novel fly ash cenospheres supported Pt–BiVO₄ composites (Pt–BiVO₄/FACs) photocatalysts were prepared by modified metalorganic decomposition process, followed by photochemical reduction. The composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and UV–vis diffused reflectance spectroscopy (DRS) techniques. The results indicate that the visible light absorption of the Pt–BiVO₄/FACs composite is greatly enhanced. The Pt element is present in the metallic form and disperses in the composite samples. Photocatalytic activities of the Pt–BiVO₄/FACs composites were evaluated by the methylene blue (MB) degradation under visible light irradiation. The results indicate that the photocatalytic efficiency is significantly improved after the Pt species was loaded and the 2 wt% Pt-loaded composite showed the highest photocatalytic activity.

Abstract: Among the new oxidation methods in advanced oxidation processes, heterogeneous photocatalysis based on UV/ titanium dioxide is one of the emerging technologies for degrading and totally mineralizing toxic and highly stable carboxylic acids from waste water has attracted great attention in last decade. The aliphatic and aromatic carboxylic acids are widely used as reactants or produced as main products or byproducts in various chemical process industries. These chemical process industries generates waste water containing significant amount of carboxylic acids, which need to be removed from waste water before disposal to natural water bodies due to the environmental restrictions and their hazardous effects on flora and fauna. This paper reviews photocatalytic degradation (PCD) process for various carboxylic acids in detail, including basic mechanism of titanium dioxide, effect of carboxylic acid structure and various reaction parameters like effect of initial concentration and kinetic study, catalyst loading, pH, adsorption and deactivation of the photocatalyst. A critical analysis of the available literature has been made and some general conclusions have been drawn related to the above mentioned parameters. The photocatalytic degradation pathways for carboxylic acids are also discussed to understand this process thoroughly.

Abstract: Degussa P-25 TiO2 powder was used as a catalyst in the photocatalytic oxidation of organics. With the objective of promoting a more effective electron-hole separation upon irradiation, the catalyst was modified with small amounts of platinum. Characterisation of the powders was done by X-Ray diffraction and SEM. Chloroform was used as a model molecule and its degradation followed using selective electrodes, with excellent results for the modified titania. Langmuir-Hinselwood kinetic was used to describe the heterogeneous oxidation of chloroform on TiO2, for low solute concentrations.