Kinetics of the photocatalytic decolorization of an Azo reactive dye in aqueous ZnO suspensions

Abstract

The photocatalytic decolorization of Remazol Red RR, a commercial azo reactive textile dye, in ZnO suspension, has been investigated in a quartz batch reactor with the use of artificial light source (UV-C). The reaction kinetics are modeled by pseudo-first-order rate law. Regression analysis related pseudo-first-order rate constant, k, to the catalyst loading, empirically as k proportional to [ZnO](0.6). The decolorization rate increases with increasing pH, attaining maximum value at pH 10. The rate constant is inversely related to the initial dye concentration, empirically according to the relation k proportional to [C-0](-1.5). Finally, the rate constant is found proportional to the square root of the light intensity as k proportional to [I] (0.5). These empirical models are therefore combined as k proportional to [ZnO](0.6) [Co](-1.5) [I](0.5).