Cu-Doped Porous ZnO-ZnAl[sub.2]O[sub.4] Nanocomposites Synthesized by Polymer-Salt Method for Photocatalytic Water Purification

In this work, the adsorption and photocatalytic properties of ZnO-ZnAl[sub.2]O[sub.4]-CuO nanosized porous composites synthesized by the polymer-salt method have been studied. To evaluate the efficiency of adsorption, experiments were carried out on the decolorization of aqueous solutions of the Chicago Sky Blue diazo dye. The adsorption process is divided into two stages, at the first stage, the dye is rapidly adsorbed on the outer surface of the composite particles (k[sub.f] = 0.0073 min[sup.−1]), at the second stage, the dye diffuses into the pores of the material (k[sub.f] = 0.0007 min[sup.−1]). It was noted that the rate of photocatalytic decomposition of the dye (k[sub.f] = 0.021 min[sup.−1]) is higher than the rate of the adsorption process, which indicates the occurrence of photocatalytic decomposition of dye molecules both on the surface of the composites and in the liquid phase. With an increase in the light intensity, the photocatalytic process is significantly accelerated, linearly at low intensities, and at high intensities (I > 100 mW/cm[sup.2]) the dependence becomes a power law.