Photooxidation of orange G in aqueous solution induced by irradiation of Fe(III)-citrate complex

The photodegradation rate of orange G (OG) in aqueous solution was enhanced in the presence of Fe(III)-citrate complexes under Xe lamp irradiation. The reaction kinetics fitted the first order reaction and the photolysis efficiency of OG was dependent on Fe(III) dosage, citric acid concentration, light intensity and initial OG concentration. OH radical is responsible for the increase of OG photolysis rate in the presence of Fe(III)-citrate complexes. The degradation of OG was more sensitive to the initial concentration of citric acid compared to that of Fe(III). The removal of OG changed from 70% to 96% corresponding to the dosage of citric acid ranged from 0.1 to 1.0 mM under conditions of pH 4.0 and 0.05 mM Fe(III).