Novel Zinc Oxide Nano Photocatalysts for Simulated Wastewater Treatment

Abstract

Pollution in general and water pollution in particular are among the most important problems facing the environment. This pollution has caused by the urgent need for industry due to the steady increase in the population therefore; most scientific research concerned with this problem. In recent years, ZnO is the most important photocatalyst, due to its non –toxicity, availability, stability, photocatalytic activity and cheapness. Unfortunately, it has two disadvantages. The first one, is fast recombination of electron-hole. Second, large energy gap (3.37 eV) causing its photocatalytic activity limited in UV region of solar light spectrum which represents 2-3%. Several methods have been used to overcome these disadvantages, including metal doping, and non-metal doping, and the coupling of another semiconductor with a low energy difference such as CuO. In the first part of this thesis, a pure Zinc oxide was prepared by aqueous sol-gel method to test its activity under UV-A irradiation in degradation of fluorescein dye as a model for anionic dyes. Some of the parameters that affect the photocatalytic activity of zinc oxide, such as pH, zinc oxide dose , and the fluorescein dye concentration, are studied. In addition, different scavengers are used to identify the most active species in photodegradation process, and the mechanism of photodegradation of fluorescein dye using ZnO is suggested.