Performance And Mechanism Of The Activation Of Persulfate By Solar Assisted Electrooxidation To Degrade Bisphenol S

As a substitute for bisphenol A（BPA）,bisphenol S（BPS）detected in different water bodies was extensively used in various industrial fields,and reducing BPS concentration and product toxicity was very important for environmental safety.Electrochemistry had received widely attention due to no secondary pollution.Based on persulfate（PS）activation,solar-assisted electrooxidation activated persulfate process was constructed.To verify the perdormance of the coupled process to active different persulfate,the degradation of BPS was investigate in various processes.The mechanism and the influencing factors such as water background conditions and operating conditions were analyzed.The properties of BPS molecular structure and energy barrier of reactions were calculated by quantum chemistry.Combining intermediate products,the possible degradation pathways of BPS were inferred.This study investigated that the feasibility of solar-assisted electrooxidation to activate various persulfate（including peroxomonosulfate,PMS and peroxydisulfate,PDS）process was proved.The degradation of BPS was improved by 18.5%in 90 min in coupling process compared to the electrooxidation alone.Due to the addition of soalr,degradation kinetic constant of BPS increased from 0.01567 min^-1 to 0.03585min^-1.Comparing to persulfate activation by solar alone and electrooxidation alone,coupling process showed synergy for BPS degradation using different anode including boron-doped diamond（BDD）and Dimensional stabilized anode（DSA）,and BDD indicated more significant synergy.In addition,effect of initial electrolytes concentration,pH,and humic acid were lower for the BPS degradation which could reach 90%.The activation processes showed optimal energy consumption(0.30k Wh·mg^-1 BPS)and lower degradation rate（94.1%）when current density was 1.0m A·cm^-2.The BPS degradation of activated PMS process was better than PDS.When the BPS degradation rate was 90%,the reaction time could be reduced by 30 min and the energy consumption also could be reduced by 0.10 k Wh·mg^-1 BPS.PMS(0.0898CNY·mg^-1 BPS)was more economical than PDS(0.1497 CNY·mg^-1 BPS).Combined with the results of scavengers and probes experiments,active species including hydroxyl radical（·OH）,sulfate radicals(SO₄^·-),singlet oxygen（¹O₂）and highly active complexes（persulfate*）generated at the electrode surface played the dominant role for the BPS degradation in coupling process.The·OH and SO₄^·-concentrations produced by PMS activation in coupling process(3.92μmol·L^-1 and3.62μmol·L^-1)was higher than those of PDS(1.42μmol·L^-1 and 1.03μmol·L^-1)in45 min,respectively.PMS and PDS had different activation mechanism to produce active species.Through energy input or electron transfer,PMS can be activated to produce·OH and SO₄^·-while PDS can only produce SO₄^·-.The cyclic voltammetric curves indicated that non-radical oxidation pathways were conducted by persulfate*generated in anode,and PMS had higher reactivity than PDS.Density function theory（DFT）resulted that the active sites of BPS mainly focused on the phenol ring.BPS was mainly attacked by SO₄^·-through single electronic transfer while·OH tendes to attack BPS through radical addition.Combined the intermediates identification,the degradation pathway of BPS was hydroxylation,sulfonation,and C-C bond.And the scondary intermediates was degraded mainly by ring opening,substitution,addition,decarboxylation,and so on.Furthermore,using quantitative structure–activity relationship（QSAR）predicted the intermediate product toxicity,identifying that coupling process could effectively reduce the biological toxicity of BPS.This study constructed the activation of persulfate by solar-assisted electrooxidation process,which was a green,economical,and high degradation rate,to provide basic theory and technical route for toxic organics degradation.