Abstract
This study involves the photocatalytic degradation of Reactive Black 5 (RB5) and Reactive Orange 4 (RO4) dyes, employing heterogeneous photocatalytic process. Photocatalytic activity of different semiconductors such as titanium dioxide (TiO2) and zinc oxide (ZnO) has been investigated. An attempt has been made to study the effect of process parameters through amount of catalyst, concentration of dye, and pH on photocatalytic degradation of RB5 and RO4. The experiments were carried out by varying pH (3–11), amount of catalyst (0.25–1.5 g/L), and initial concentration of dye (10–100 mg/L). The optimum catalyst dose was found to be 1.25 and 1 g/L for RB5 and RO4, respectively. In the case of RB5, maximum rate of decolorization was observed in acidic medium at pH 4, whereas the decolorization of RO4 reached maximum in basic region at pH 11. The performance of photocatalytic system employing ZnO/UV light was observed to be better than TiO2/UV system. The complete decolorization of RB5 was observed after 7 min with ZnO, whereas with TiO2, only 75% dye degraded in 7 min. In the case of RO4, 92 and 62% decolorization was noticed in the same duration.
Highlights
Textile industries produce large volume of colored dye effluents which are toxic and non-biodegradable [1]
The results clearly show that zinc oxide (ZnO) is a better catalyst for the degradation of Reactive Orange 4 (RO4) dye
The results show that the photocatalytic decolorization of both the dyes in aqueous ZnO can be described by the first-order kinetic model, ln (C0/C) = kt, where C0 is the initial concentration and C is the concentration at any time, t
Summary
Textile industries produce large volume of colored dye effluents which are toxic and non-biodegradable [1]. One of the prominent and most widely used types of azo dyes, are typically azo-based chromophores combined with different reactive groups. They are extensively used in many textile-based industries because of their favorable characteristics, such as bright color, water-fastness, and simple application [2]. Up to 50% of reactive dyes are lost through hydrolysis during the dyeing process, and a large quantity of the dyes appears in wastewater [3] These dyestuffs are designed to resist biodegradation and are barely removed from effluents using conventional wastewater treatments, such as activated sludge [4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
