Photocatalytic Degradation Kinetics and Mechanism of Monoazo Dye Acid Yellow 17 by UV/TiO2 in Aqueous Solution

Abstract

In order to explore the removal methods, transformation, environmental fate, effect and potential risk of dyes in environmental water, monoazo dye acid yellow 17 (AY17) was selected as model compound to investigate the degradation possibility in different advance oxidation processes (AOPs), and the degradation efficiencies followed the order of UV/H2O2 <UV/Na2S2O8≈UV/FeSO4·7H2O <UV/KHSO5 <UV/TiO2. Subsequently, the different parameters such as catalyst amounts, reaction temperature, substrate concentration and initial pH values affected the degradation rate significantly in the system of UV/TiO2. The results indicated that the degradation of AY17 followed the pseudo-first-order kinetics, and the rate constant was 0.0112 min-1. Additionally, the highest degradation rate constant was obtained when the catalyst dosage was 3 g·L-1, higher reaction temperature was more beneficial to the degradation of AY17, and the degradation rate constants decreased with increasing substrate concentration and initial pH values. Lastly, the degradation intermediates were also identified by GC/MS, and the degradation pathways were also proposed at the initial stage of photocatalytic process, including the breakage of azo bonds, groups substitution of·OH on aromatic ring and cleavage of pyrazol ring.