Photocatalytic treatment of textile effluent

Abstract

Textile industry, which meets the demand of ever growing human population, is one of the sources of non-biodegradable toxic effluents. The origin of toxicity in such effluents is mainly from the complex aromatic dye compounds. Various types of dyes have different environmental aspects. Reactive azo dyes are one of the most extensively and commonly used dyes and belong to one of the most polluting dye class. Most of the conventionally used techniques for such waste water have been found to be either ineffective in treatment or merely resulting in transfer of pollutants from one phase to the other. Recently, a great amount of research effort is being made in development and understanding of alternative methods of waste treatment. Advance oxidation processes (AOPs) are being widely studied for this purpose. In this thesis, the degradation and kinetic studies of Reactive Red 120 dye (RR120), Reactive black 5 dye (RB5) and simulated effluent containing dye mixture and salts respectively have been studied. In case of RB5 dye, RR120 dyes, the degradation characteristics have been investigated in the presence of UV light using Degussa P25 TiO2. Preliminary investigations were made to determine the effect of hydrolysis, solar photolysis, and UV chamber photolysis on dye decolorization kinetics. The equilibrium adsorption of dye on TiO2 was studied at various pH values. The effect of various parameters like pH, catalyst load, initial dye concentration, area to volume ratio of the reactor, and dye salts were also studied. The adsorption of dye on the semiconductor showed a strong dependence on the pH and followed a Langmuir adsorption model. Finally, the mineralization characteristics of dye were studied simultaneously with dye decolorization. The degradation studies of simulated textile effluent were made in shallow pond slurry reactor. The equilibrium adsorption studies of two dyes RB5 and RR120 were compared as single dyes with their mixture solution.