Removal Of Acetaminophen By Iron-copper Bimetallic Catalyst Active Persulfate: Degradation Mechanism

In this paper,different types of Fe-Cu bimetallic catalysts were prepared.In order to research the performance of prepared Fe-Cu catalysts for persulfate?PS?activation,acetaminophen?APAP?,a typical endocrine disruptors?EDCs?was selected as target compound,the optimal conditions for Fe-Cu bimetals/PS systems were then obtained,and mechanism of PS activation by Fe-Cu bimetals were also proposed.To enhance the oxidation of PS system,CuO was introduced into Fe²⁺/PS system to achieve the synergistic effect of Fe-Cu bimetals.The degradation efficiency of APAP was studied under the optimal condition(initial pH=6.5,PS=0.8 g L^-1,Fe²⁺=0.7 mM,CuO=0.3 g L^-1).The results indicated higher efficiency of Fe-Cu bimetals?92%within 90 min?than Fe²⁺/PS and CuO/PS system?79%and 10%?.The activation mechanism of Fe²⁺/CuO/PS system was clarified by the characterization of fresh and recycled CuO?FESEM,XRD,XPS?and the concentration changes of Fe²⁺,Cu⁺during reaction.As result,Fe²⁺in the solution could bind with the CuO to form Fe?II?and further reduced Cu?II?into Cu?I?,which could release into the solution to participate oxidation reactions.Quenching experiment was performed to verify the active radicals in the Fe²⁺/CuO/PS system.It was found that both sulfate radical and hydroxyl radical were generated in the Fe²⁺/CuO/PS system.Flower-like Fe₂O₃ was prepared by oil-bath reflow method as the precursor and then Fe₂O₃@Cu₂O was synthesized by polyol method.Furthermore,FESEM,FTIR and other characteristics of Fe₂O₃@Cu₂O were analyzed.The degradation efficiency of APAP in Fe₂O₃@Cu₂O/PS system was investigated.Under condition of initial pH=6.5,PS=0.6 g L^-1,and catalyst dosage=0.3 g L^-1,the remove rate of APAP could reached 90%.However,in the Fe₂O₃/PS and Cu₂O/PS systems,APAP removal rate were 35%and 61%.Valence transformation between Cu?I?/Fe?III?in Fe₂O₃@Cu₂O was the main reason for PS activation by Fe₂O₃@Cu₂O.During reaction,Cu?I?could reduce Fe?III?to form more activated Fe?II?to trigger reaction.The intermediate product of APAP in Fe₂O₃@Cu₂O/PS system was analyzed by GC-MS,and degradation pathway was purposed.Quenching experiment demonstrated that sulfate radicals were identified as the main active radicals in Fe₂O₃@Cu₂O/P system.Nano oxygen-deficient CuFe₂O₄ was prepared by hydrogenation technology to enhance the catalytic activity of CuFe₂O₄ to PS.Furthermore,FESEM,EDS and XPS were used to characterize oxygen-deficient CuFe₂O₄.Under optimal condition(initial pH=6.5,PS=0.8 g L^-1,catalyst=0.3 g L^-1),removal rate of 100 mg L^-11 APAP in 60 min could reached 91%.However,degradation rate of APAP using CuFe2O4/PS system was only reached 20%,which proved that the formation of oxygen-deficient enhanced catalytic activity of CuFe₂O₄ to PS.It is speculated that the presence of oxygen-vacancies enhanced the electron transfer ability and reduction of catalyst,therefore,high activity for PS.In addition,impact of dissolved oxygen?DO?and anions for oxygen-deficient CuFe2O4/PS system was analyzed,and the results showed that both of DO and anions in the solution have a certain inhibition on oxygen-deficient CuFe₂O₄/PS system.GC-MS was used to analyze the degradation intermediate of APAP,and two APAP degradation pathways were purposed...