Degradation of Acid Yellow 17 Dye in Aqueous Medium by Advanced Oxidation Processes

Abstract

Dyes in wastewater are one of the major pollutants which concern the scientific community. For their removal the advanced oxidation processes (AOPs) play an important role. In the present research work, the degradation of acid yellow 17 (AY 17) dye was studied by various AOPs. In these processes, various types of oxidants (such as peroxymonosulphate (HSO5 – ), persulphate (S2O8 2– ), hydrogen peroxide (H2O2) and homogenous catalysts (such as Ferrous (Fe2+) and ferric ion (Fe3+) were used. For degradation of AY 17 dye from water solution (model and natural) by direct photolysis, UV/oxidant, photo-Fenton, photo-Fenton-like, UV/HSO5 – /Fe2+, UV/S2O8 2−/Fe2+, Fenton-like and Fenton processes has been investigated in detail. The ratio among AY17 dye, oxidant and catalyst in photo-Fenton, photo Fenton-like, Fenton-like, UV/HSO5 – /Fe2+, UV/S2O8 2– /Fe2+ were 1.5:11:1, 1.5:111:1, 1:15:1, 1:14:7, 1:7:3.5 respectively. All applied processes were found to be the most efficient at pH 3, while UV-254nm light source increased the degradation efficiency. The efficiency of AY 17 dye degradation increased with increasing the initial concentration of the oxidants (H2O2, HSO5 – and S2O8 2– ) and catalysts (Fe2+ and Fe3+). Consequently the efficiency of AY 17 dye degradation by these processes decreased with increasing the initial concentration of the target pollutant. Although the rate of degradation increased with increasing AY 17 dye concentration, while the rate constant (kobs) decreased with increasing AY 17 dye concentration. The degradation of AY 17 dye with respect to initial concentration follow pseudo first order kinetics. While in the case of photo-Fenton, photo-Fenton-like, Fenton-like, UV/HSO5 – /Fe2+ , UV/S2O8 2– /Fe2+ and Fenton processes the degradation of AY 17 followed second order kinetics at different temperature. xii The activation energy (Ea * ) of photo-Fenton, photo-Fenton-like, Fenton-like, UV/HSO5 – /Fe2+, UV/S2O8 2– /Fe2+ were 18.24, 40.95, 36.42, 60.88 and 38.16 KJ/mol respectively. The entropy of activation of degradation photo-Fenton, photo-Fenton like, Fenton-like, UV/HSO5 – /Fe2+, UV/S2O8 2– /Fe2+ were 6.03, 14.30, 11.62, 21.50 and 12.30 KJ/mol.K respectively. High degradation was achieved at stirring rate 100 rpm. The degradation of AY 17 dye by applied AOPs was found due to the reaction of ●OH and SO4 ●− radicals. The efficiency of the ●OH and SO4 •– radicals were, however, inhibited in the presence of radical scavengers, such as a certain inorganic anions (sulphate, chloride, carbonate and bicarbonate). The percent degradation of AY 17 dye in model samples by photo-Fenton, photo-Fenton-like, Fenton-like, UV/HSO5 – /Fe2+, UV/S2O8 2– /Fe2+ were 94%, 93%, 83%, 86% and 84% respectively. While the percent degradation of AY 17 dye in natural water samples were 59%, 60%, 57%, 65% and 63% respectively. Results of this study suggest that photo Fenton process is more efficient method for the removal of AY 17 dye, from aqueous medium. Key words: Acid Yellow 17 dye, Wastewater, Advanced Oxidation Processes (AOPs), Fenton process, Fenton-like, photo-Fenton, second order kinetics, scavengers, UV-254 nm, HSO5.....