Study On Enhancing Degradation Performance Of EF-FeO_x System With Complexing Agent EDDS At Neutral PH

Dye has provided a lot of convenience for human production and life,but it also produces a lot of dye wastewater in the process of manufacture,processing,and using.Dye wastewater contains a lot of organic matter that is difficult to decompose,and has the characteristics of high COD,high chroma and poor biodegradability.If dye wastewater is discharged directly into the environment without treatment,it will harm not only aquatic animals,plants and their ecosystems,but also human health after coming into touch with humans in various ways.As a result,a method for efficiently treating dye wastewater is required.This study investigated the degradation performance of the chelator ethylenediamine-N,N’-disuccinic acid（EDDS）assisted sacrifice-anode electro-Fenton（EF-Fe O_x）system using rhodamine B（Rh B）,which is a typical pollutant in dye wastewater,as the target pollutant.Firstly,the degradation performance of Rh B was monitored and compared in several reaction systems.The impacts of several influencing variables on the degradation of Rh B were then explored,including initial p H value,H₂O₂ dosage,current density,and EDDS dosage.On the basis of above single factor experiments,response surface methodology（RSM）was used to analyze the interaction of influencing factors and optimize the reaction conditions.The results revealed that the EDDS/EF-Fe O_x system had the best performance for Rh B wastewater treatment,with a greater Rh B removal efficiency than other systems.The removal efficiency of Rh B reached 89.14%at ideal conditions of H₂O₂0.4 m M,EDDS 0.21 m M,and current density 0.77 m A/cm²,which was near to the predicted value（90.50%）.Rh B was found to be effectively degraded by the EDDS/EF-Fe O_x system,with chromophore cleavage being the predominant degradation pathway.Two EF-Fe O_xsystems with or without EDDS were examined in terms of Fe（Ⅱ）/Fe（Ⅲ）concentration change and degradation performance.The results revealed that adding the complexing agent EDDS to the original EF-Fe O_x system considerably improved the degrading performance,and the removal efficiency of Rh B was raised by64.26%.The Fenton reaction was crucial in the Rh B degradation process.In the reaction system,EDDS could complex with Fe（Ⅱ）/Fe（Ⅲ）to keep their reaction activity in solution and enhance the generation of the hydroxyl radical（·OH）.Experiments with electron paramagnetic resonance（EPR）detection and free radical quenching revealed that·OH was the dominant active radical in the degradation of Rh B,and the degradation mostly happened via the homogeneous reaction process,while superoxide radical（O₂^-·）also played an important role in promoting the generation of·OH.