Photo Catalytic Degradation of Effluent of Iron and Power Plant Industries in Aqueous Solution by CDS Nano Catalyst Using UV Irradiation

Abstract

The iron and power plant industries consume significant amount of water during the power generation and finishing operations. In this operation a used water having high chemical oxygen demand contents and the waste water discharged in rivers or public sewage treatment plant. Their treatment has been a necessary aspect for human prosperity and ecological environment. This paper shows the detailed study of photo catalytic degradation of effluent carried out in the presence of an aqueous solution of TiO2 nano catalyst irradiated with UV light in a batch reactor. It was observe that photo catalytic degradation of effluent obey pseudo first order kinetics according to langum-uir Hinshelwood model. The influences of various factors in rate of reaction are, initial effluent concentration, catalyst concentration and UV light irradiation time on degradation efficiency were scientifically studied. The degradation of eluent was determined by Photo colorimeter and determines the COD degradation through transmittance of effluent. Keywords - Photo catalytic degradation, TiO2 nano catalyst, COD, AOP's, Iron and power plant waste water. I. INTRODUCTION Environmental pollution is produced either by a natural source or by some anthropogenic activity, or by human. Which has an adverse effect on humans, animals, plants and materials? The inordinate population growth, fast industrialization, rapid urbanization and modified agricultural operations have intensified the pollution of air and water both and as a consequence, the human health is seriously affected by this environmental and ecological disorder. If this situation is not controlled timely, it would become a malignant problem for the survival of mankind on this planet. Environment pollution by organic pollutant also sets several ecological problems, which is increased by the fact that most of them are difficult to degrade using standard biological methods. For the removal of such recalcitrant pollutants some traditional, physical techniques such as adsorption on activated charcoal, ultra filtration, reverse osmosis and coagulation is used efficiently. Nevertheless they are nondestructive. Recently there has been considerable interest on the utilization of advanced oxidation process (AOPs) for the destruction of organic compounds in contaminated water. The key advantage of this degradation method is that it can be carried out under ambient condition and lead to complete degradation of organic compounds. Among the advanced oxidation process heterogeneous photo catalysis appears as an emerging technology leading to the total mineralization of most of the organic pollutants. If a suitable semiconductors are irradiated with visible or UV light electron excitation from Valance band to conduction band results and a vacancy or hole is left in the valance band such have the effect of a positive charge. Thus in turn generates the formation of holes on the surface of the semiconductor, which can react with oxygen, water and hydroxide ion to form hydroxyl radicals. Furthermore, super oxide radicals are formed from the reaction of excited electrons with oxygen molecules. The highly reactive oxygen species so formed react with the organic pollutants resulting in their oxidation. The kinetics of photo catalytic degradation of many organic compounds in TiO2 suspensions under visible irradiation has often been matched to the simple langmuir-hinshelwood equation -1 r = -dc/d t ……equation-1