Degradation Of Triphenyl Phosphate By Different Iron-based Materials Activated Bisulfite

Triphenyl phosphate?TPHP?,a typical pollutant of phosphorous flame retardants,has attracted wide attention due to easily releasing into various environmental media and causing potential harm to them.In recent years,iron-based advanced oxidation processes?Fe-AOPs?play an important role in the research of pollutant degradation because of its economic,low toxicity and high efficiency.In Fe-AOPs studies,there were few studies on nano zerovalent iron?n ZVI?or metal organic frameworks?MOFs?as catalyst and bisulfite as oxidant,so the degradation mechanism was still unclear.In this paper,the degradation of TPHP was studied by selecting n ZVI and MIL-88A,a typical MOFs,as catalysts and bisulfite as oxidant.The main results are as follows:?1?n ZVI particles were prepared by wet reduction of Fe Cl₂·4H₂O with Na BH₄ and applied to the AOPs of bisulfite.According to the SEM,XRD and XPS analysis,the n ZVI of a kind of spherical particles with chain aggregation was successfully prepared.Under the optimum conditions?TPHP concentration 2 mg/L,n ZVI dosage 0.5 m M,bisulfite concentration 2.0 m M,initial p H of 3.0?,the degradation efficiency of TPHP after 60 min reached 98.2%which was much higher than that of n ZVI,Fe²⁺,bisulfite,Fe²⁺/bisulfite systems,demonstrating the outstanding synergistic effect between n ZVI and bisulfite.Both Cl^-and NO₃^-inhibited the removal of TPHP and the inhibition effect was Cl^->NO₃^-.The surface of n ZVI particles after reaction was seriously damaged and the quenching experiment proved that there were mainly sulfate radicals?·SO₄^-?in the system.The degradation of TPHP was mainly attributed to the dissolution of Fe²⁺and a series of oxidation reactions with bisulfite.Simultaneously,generated·SO₄^-attacked and degraded TPHP.?2?With Fe Cl₃·6H₂O and fumaric acid as precursors,the MIL-88A was prepared by solvothermal method and used for the activation of bisulfite.This work firstly explored the best preparation conditions of MIL-88A which were:the proportion of solvent?H₂O/DMF?=1:0,crystallization temperature?T?=65°C,crystallization time?t?=0.5 h.On the basis of SEM?FTIR and XPS analysis,MIL-88A presented a standard hexagonal rod structure and?Fe^III was the main active site.Selecting the MIL-88A prepared under the excellent conditions as catalyst,a MIL-88A/bisulfite system was constructed.Under the optimal experimental conditions?MIL-88A dosage 0.2 g/L,bisulfite concentration 2.0 m M,ambient p H??6.40??,the removal efficiency of 2 mg/L TPHP reached 96.6%after 30 minutes.In addition,the degradation of TPHP was inhibited by anions in waterbody and followedindicating that the removal of TPHP was mainly attributed to the heterogeneous reaction between?Fe^III and bisulfite.In this study,two Fe-AOPs systems were established to degrade TPHP,and the degradation kinetics and reaction mechanism were explored respectively,providing experimental basis for the pollution remediation of water TPHP by Fe-AOPs.