Solar Light Induced Glass-Supported Zinc Oxide Catalyzed Degradation of Allura Red AC in Aqueous Solution

Abstract

The glass-supported zinc oxide (ZnO)-catalyzed photodegradation of Allura Red AC (AR) was studied in aqueous solution as function of solar light irradiation time, solution pH, amount of ZnO, initial dye concentration, some inorganic anions ( $${\text{SO}}_{4}^{{2 - }}$$ , $${\text{CO}}_{3}^{{2 - }}$$ , Cl‒, $${\text{NO}}_{3}^{ - }$$ ), and hydrogen peroxide. The maximum rate of AR degradation was observed in the acidic solution at pH 3. The degradation rate of AR increased with increased dosage of the ZnO, and decreased with increased initial concentration of the dye solution. The presence of $${\text{NO}}_{3}^{ - }$$ ion increased the photodegradation rate while, $${\text{SO}}_{4}^{{2 - }}$$ , $${\text{CO}}_{3}^{{2 - }}$$ , and Cl‒ decreased the reaction rate. The addition of H2O2 showed a synergistic effect on dye degradation. However, mannitol and ethylenediaminetetraacetic acid (EDTA) significantly reduced the photodegradation of AR indicating hydroxyl radicals played a key role in dye degradation process. Hence, these results confirm that the glass-supported ZnO-catalyzed photodegradation can be used to clean dye-contaminated industrial wastewater.