Natural Antioxidants Enhance The Degradation Of Orange-G By Different Photo-Activated H₂O₂/PDS Oxidation Systems

Advanced oxidation processes based on sulfate radical(SO₄^·-)and hydroxyl radical（·OH）has good application prospects in dye wastewater treatment due to its advantages of high efficiency and complete degradation of organics.Among many activation methods for persulfate and hydrogen peroxide,iron ion activation is the most promising activation technology due to the high efficiency and low secondary pollution.In iron ion activation technology,accelerating the iron cycle of Fe³⁺/Fe²⁺is closely related to the degradation efficiency of organics.Enhanced reagent was demonstrated to promote the Fe³⁺/Fe²⁺iron cycle.Natural antioxidants have the characteristics of high safety,strong oxidation resistance and good complexation,and was good enhanced reagent.Therefore,this study has studied the performance and enhanced mechanism of adding different types of natural antioxidants under UV light on the degradation of Orange-G by iron ion activated PDS and H₂O₂ in homogeneous and heterogeneous systems.The main research contents and conclusions are as follows:（1）Natural antioxidants enhanced the degradation of Orange-G by Fe³⁺-activated H₂O₂/PDS was discovered,and rosmarinic acid has the best enhanced ability.By analyzing the degradation rate constant of Orange-G,the utilization efficiency of H₂O₂and PDS,the mineralization ability of the system,and the impact of p H,it was proved that PDS,as an oxidant in the system,was slightly superior to H₂O₂ under near-neutral conditions.（2）The performance of natural antioxidants enhanced heterogeneous UV-Fenton system on Orange-G degradation was evaluated.The addition of natural antioxidants could promote the leaching of Fe³⁺and Fe²⁺from PSF,thus promote the degradation of Orange-G.In this system,the best natural antioxidant was rosmarinic acid.When0.05 mmol/L rosmarinic acid was added,the degradation rate constant of Orange-G was as high as 0.889 min^-1.（3）The enhancement mechanism of rosmarinic acid on Orange-G degradation in heterogeneous UV-Fenton system with PSF as catalyst was elucidated and the ecotoxicity of degradation intermediates was evaluated.because rosmarinic acid has both reduction and complexation abilities,it could effectively promote the degradation and mineralization of Orange-G;When the intermediates continuously degraded,the iron ions could be re-adsorbed on catalyst,avoiding the loss of iron ions and secondary pollution.Besides,the additional rosmarinic acid couldn’t change the degradation pathway of Orange-G,but some more toxic degradation products would be formed during the degradation of Orange-G and rosmarinic acid,the ecotoxicity would be eliminated when all the intermediates were mineralized to oxalic acid.