Photodegradation Kinetics and Color Removal of 2-(4-hydroxyphenylazo) Benzoic Acid by Advanced Oxidation Processes

Degradation kinetics and color removal of 2-(4-hydroxyphenylazo)benzoic acid azo dye by the hydrogen peroxide/ultraviolet irradiation and sodium hypochlorite/ultraviolet irradiation processes were carried out in Spectroline CM-10A Model ENF-260C/FE photoreactor which has ultraviolet lamps irradiating at 254 and 365 nm wavelengths. All experimental studies were performed at room temperature in 0.04 M Britton Robinson buffer (pH 2-12). For this purpose, the degradation kinetics of 2-(4-hydroxyphenylazo)benzoic acid was investigated depending on pH, initial dye concentration and hydrogen peroxide concentration. Optimum pH and hydrogen peroxide concentration were determined as pH 10 and 3.57x10-2 M, respectively, for 3.5x10-5 M 2-(4-hydroxyphenylazo)benzoic acid. Optimum pH value in 1.55x10-3 M sodium hypochlorite medium has been found as pH 8 for 3.5x10-5 M azo dye. These methods used for degradation of dye are compared, it is concluded that sodium hypochlorite/ultraviolet irradiation and sodium hypochlorite methods are more effective than hydrogen peroxide/ultraviolet irradiation and hydrogen peroxide methods because of color removal of 83% and 64%, respectively.