ABSTRACT
Effluents from dyeing and printing done in textile industries contain complex mixtures of dyes that are highly colored with high biological oxygen demand, chemical oxygen demand, and unbearable odor, which is ethically not acceptable. It is a threat to mankind and has added a new dimension to the problem of water pollution. Heterogeneous photocatalysis is an advanced oxidation process that can be successfully used to oxidize many organic pollutants present in aqueous systems. In this research work, the effect of various parameters on the photocatalytic degradation of commercially available textile azo dye (Reactive Orange 16) in aqueous heterogeneous suspension has been studied. Parameters such as pH, amount of photocatalyst, dye concentration, and nature of photocatalyst as main operational parameters were selected, and their influence on degradation efficiency has been investigated. The progress of reaction was observed spectrophotometrically. The kinetic analysis of photocatalytic degradation reveals that the degradation follows pseudo first-order kinetics according to the Langmuir–Hinshelwood model. The trace quantities of transition metal ions (Fe2+, Cu2+, Mn2+, Zn2+) increase the photocatalytic degradation efficiency to some extent. This may be due to the introduction of new trapping sites by the incorporation of transition metal ions on semiconductor surface. A probable mechanistic pathway has been proposed.
