LAUSR

The performance of UVA-LEDs assisted peroxymonosulfate (PMS)/Fe2+ system was evaluated on carmoisine (E122) decolorization. Complete color removal was obtained under the conditions of pH=3.0, PMS=1.5 mM, Fe2+=1 mM and 25 min reaction time. UVA-LEDs were preferable compared to conventional UVA lamp in terms of decolorization. The functions of Co2+, Cu2+, Mn2+ and Fe2+ were compared and their results showed that Co2+ and Fe2+ had the highest efficiencies. Moreover, the presence of chloride ion showed a double role in different concentrations in which promotional effect was observed in 100 mM Cl−<, while inhibitory effect occurred in 1–10 mM Cl−. However, the high concentration of chloride had no influence on mineralization of E122. The scavenging results demonstrated that the UV irradiation increased the contribution of HO•. In addition, in the presence of chloride ion, HOCl along with sulfate and hydroxyl radicals were the major oxidative agents.