Photo-oxidation of Mordant Yellow 10 in aqueous dispersions of ferrihydrite and H 2O 2

Abstract

To investigate the effect of ferrihydrite on the degradation of azo dyes, Mordant Yellow 10 (MY10) was selected as a model azo dye. The photodegradation of MY10 was studied in the presence of both ferrihydrite and hydrogen peroxide under UV irradiation. The results showed that no degradation of MY10 was detected in the H 2O 2/UV system without ferrihydrite. When a small amount of ferrihydrite (0.5 g L −1) was introduced into the reaction system, it was found that the degradation of MY10 with H 2O 2 occurred even in the dark, and UV irradiation could significantly accelerate the degradation rate. Hydroxyl radicals ( OH) generated through the catalytic decomposition of H 2O 2 by ferrihydrite play a major role in the oxidation of MY10. In addition, the effect of key operating parameters such as initial pH of the solutions, initial concentration of H 2O 2 and temperature was studied on the photo-oxidation of the dye. The results indicated that the degradation rates increase with decreasing initial pH values (from 9 to 3) and increasing concentration of H 2O 2 (from 1 to 5 mM) and temperature (from 288 to 318 K).