PREPARATION AND CHARACTERIZATION OF ZnO/CuO SEMICONDUCTOR AND PHOTOCATALYTIC ACTIVITY ON THE DECOLORIZATION OF DIRECT RED 80 AZODYE

Zinc oxide, an n-type semiconductor, has been used as photocatalyst for contaminated water purification by organic compounds. The addition of a p-type semiconductor as copper oxide could increase the catalytic efficiency through the p-n junction in order to decrease the electron-hole recombination. In this work, zinc and copper oxides containing 1.0, 3.0, and 5.0 % of copper were prepared by manual grinding, followed by heat treatment at 300 degrees C during 5 h. The zinc oxide and copper oxide mixture as well as their precursors were characterized by x-ray diffraction, diffuse reflectance, scanning electron microscopy, and x-ray fluorescence. The photocatalytic efficiency was verified by the direct red 80 tetraazodye decolorization using UV radiation under pseudo-first order conditions at natural pH (7.5-8.0) and 30 degrees C. The highest photocatalytic activity occurred to the semiconductor containing 1.0 % copper oxide, whose decolorization rate constant was equivalent to 6.40x10(-2) min(-1), that is, 17.4 % larger in comparison to ZnO, 5.45x10(-2) min(-1).