Persulfate Enhanced Photocatalytic Degradation Of Bisphenol A Under Visible Light

Environmental pollution and energy shortage are two important problems faced by human beings in the development of the world today.This study used waste batteries as raw materials to prepare ZnFe₂O₄ catalysts with visible light response by sol-gel method,and further synthesized ZnFe₂O₄/g-C₃N₄ composite catalysts to construct persulfate（PDS or PMS）mediated heterogeneous photocatalytic（Vis）system,which treats bisphenol A（BPA）in the water,the main contents are as follows:（1）Vis/ZnFe₂O₄/PDS system was constructed with ZnFe₂O₄ as catalyst.The morphology,composition and optical structure of ZnFe₂O₄ were characterized.The degradation efficiency of BPA in Vis/ZnFe₂O₄/PDS process reached 96.5%in 120 min at natural p H.Photoluminescence（PL）spectroscopy combined with amperometric tests showed that PDS captured the photogenerated electrons,and effectively inhibited the recombination of photogenerated charge carriers.The electron paramagnetic resonance（EPR）test and quenching experiments verified the main active species in the photocatalysis process.It was found that SO₄^·–,^·OH and photogenerated holes played an important role in the oxidation of BPA.The best removal efficiency was got when PDS was 1.0 m M and the dosage of ZnFe₂O₄ was 0.3 g/L under natural p H condition.In addition,ZnFe₂O₄ has good reusability and photocatalytic stability.The construction of Vis/ZnFe₂O₄/PDS system for the treatment of BPA conforms to the concept of“treating waste with waste”and provides a new feasible idea for the recycling of waste alkaline Zn-Mn batteries.（2）In order to further improve the photocatalytic activity of the catalyst,ZnFe₂O₄and g-C₃N₄ were combined to prepare ZnFe₂O₄/g-C₃N₄ composite catalyst,and Vis/ZnFe₂O₄-g-C₃N₄/PMS system was constructed and applied to the treatment of BPA.The activity of ZnFe₂O₄-g-C₃N₄ was investigated,and the surface morphology and structure of ZnFe₂O₄-g-C₃N₄ were characterized.The degradation efficiency of BPA in Vis/ZnFe₂O₄-g-C₃N₄/PMS process reached 97.7%within 60 min when PMS was 0.5m M and ZnFe₂O₄-g-C₃N₄ was 0.3 g/L under natural p H.Quenching experiments showed that non-radicals pathway mainly contributed to the oxidation of BPA.The results of PL and amperometric tests showed that the composite catalyst had better performance than the monomer catalyst,and PMS could effectively inhibit the recombination of photogenerated charge carriers.Mott-Schottky test shows that the synthesized ZnFe₂O₄-g-C₃N₄ belongs to n-n type heterojunction,and the formation of heterojunction is conducive to the interfacial transfer of charge carriers.The system showed a certain selectivity of degradation for different pollutants,and it was used to treat actual wastewater.The influence of common anions on the process and the reusability and photocatalytic stability of the catalyst were also investigated.