ZnS-embedded porous carbon for peroxydisulfate activation:Enhanced electron transfer for bisphenol A degradation

Transition metal sulfides have garnered increasing attention for their role in persulfate activation,a crucial process in environmental remediation.However,the function of metal sulfides without reversible valence changes,such as ZnS,remains largely unexplored in this context.Here we report ZnS-embedded porous carbon(ZnS-C),synthesized through the pyrolysis of Zn-MOF-74 and dibenzyl disulfide.ZnS-C demonstrates remarkable activity in activating peroxydisulfate(PDS)across a wide pH range,enabling the efficient mineralization removal of bisphenol A(BPA).Through electrochemical investigation and theoretical simulations of charge density distributions,we unveil that the electron transfer from BPA to PDS mediated by the ZnS-C catalyst governs the reaction.This study,both in theory and experiment,demonstrates metal sulfide as electron pump that enhances electron transfer efficiency in PDS activation.These findings redefine the role of metal sulfide catalysts,shedding new light on their potential for regulating reaction pathways in PDS activation processes.

Involvements of chloride ion in decolorization of Acid Orange 7 by activated peroxydisulfate or peroxymonosulfate oxidation

The effects of chloride anion （Cl-） （up to 1.0 mol/L） on the decolorization of a model compound,azo dye Acid Orange 7 （AO7）,by sulfate radical （SO4-） based-peroxydisulfate （PS） or peroxymonosulfate （PMS） oxidation under various activated conditions （UV 254 nm /PS,Thermal （70°C/PS,UV 254 nm /PMS,Co 2＋ /PMS） were investigated.Methanol and NH4 ＋ were used as quenching reagents to determine the contributions of active chlorine species （dichloride radical （Cl2-.） and hypochlorous acid （HClO））.The results indicated that the effects of Cl- on the reaction mechanism were different under various activated conditions.For UV/PS and Thermal/PS,the inhibition tendency became more clear as the Cl- concentration increased,probably due to the reaction between Cl- and SO4-.and the generation of Cl2-.or HClO.For UV/PMS,Cl- did not exhibit inhibition when the concentration was below 0.1 mol/L.As Cl- concentration reached to 1.0 mol/L,the decolorization rate of AO7 was,however,accelerated,possibly because PMS directly reacts with Cl- to form HClO.For Co2＋ /PMS,Cl- exhibited a significant inhibiting effect even at low concentration （ 0.01 mol/L）.When Cl- concentration exceeded 0.1 mol/L,the activation of PMS by Co 2＋ was almost completely inhibited.Under this condition,HClO maybe played a major role in decolorization of AO7.The results implicated that chloride ion is an important factor in SO4-.-based degradation of organic contamination in chloride-containing water.