Comparative Study On Degradation Of Bisphenol A And Bisphenol S By Different UV-based Advanced Oxidation Processes

Bisphenol compounds（BPs）are a common class of endocrine disruptors.Due to their complex structures,completely removing them using conventional wastewater treatment techniques is challenging.Advanced oxidation technologies based on ultraviolet light（UV-AOPs）,including ultraviolet/hydrogen peroxide（UV/H₂O₂）,ultraviolet/persulfate（UV/PDS）,and ultraviolet/chlorine（UV/Cl）,generate a large number of active radicals compared to traditional oxidation technologies.This effectively removes pollutants that are difficult to degrade in water.Under UV irradiation,UV-AOPs produce highly active free radicals such as sulfate radicals(SO₄^·-),hydroxyl radicals（·OH）,and chlorine active species（RCS）.These radicals convert organic pollutants with strong toxicity and stable chemical properties in water into low-toxicity and easily biodegradable small molecular organic compounds.However,the actual water background is complex and variable,and changes in water p H and the presence of dissolved organic compounds（DOM）may impact the degradation efficiency of UV-AOPs.Currently,there are gaps in research regarding the impact of different water environmental factors on the degradation of BPs by UV-AOPs.Additionally,there are few comparative studies on the kinetic differences and toxicity changes during the degradation of BPs using different UV-AOPs.Therefore,this study aimed to use typical endocrine disruptors such as bisphenol A（BPA）and bisphenol S（BPS）as representative pollutants,and UV/H₂O₂,UV/PDS,and UV/Cl as representative AOPs,to investigate their degradation efficiency for the target pollutants and changes in system toxicity.The study aimed to reveal the applicability characteristics of different UV-AOPs for the degradation of organic pollutants,clarify the effects of water environmental factors and free radical participation mechanisms,explore the toxicity changes of different UV advanced oxidation technologies during the degradation of organic pollutants,and comprehensively evaluate the applicability of different UV-AOPs using quantitative structure-activity relationship（QSAR）models.The main contents and conclusions of the study are as follows:（1）Kinetics and influencing factors of BPA and BPS degradation by UV-AOPs:By comparing and analyzing the kinetic differences of BPA and BPS degradation using UV/H₂O₂,UV/PDS,and UV/Cl,the results showed that the degradation efficiency of BPA,from high to low,was UV/PDS(0.3185±0.034 min^-1)>UV/H₂O₂(0.0740±0.017 min^-1)>UV/Cl(0.0048±0.001 min^-1).The degradation efficiency of BPS,from high to low,was UV/H₂O₂(0.0820±0.006 min^-1)>UV/PDS(0.0444±0.003 min^-1)>UV/Cl(0.0217±0.001 min^-1).Under the same conditions,the degradation rate of BPS was lower than that of BPA.The p H of the water affected the degradation kinetics of UV-AOPs,as it determined the dissociation form of organic compounds.Under alkaline conditions（p H=9.0）,the degradation rate significantly increased.DOM had an inhibitory effect on the degradation of BPs by UV-AOPs,and this effect increased with the increase in DOM concentration.Quenching experiments showed that the contribution of in the degradation process of BPA was higher than that of·OH,while·OH played a leading role in the degradation of BPS.（2）Toxicity changes during BPA and BPS degradation by UV-AOPs:Compared with dark chlorination,UV/Cl treatment reduced the acute toxicity of BPs.Coupling UV radiation with the Na Cl O process can reduce the formation of organic chlorinated compounds and their toxic effects.The acute toxicity of BPS during UV-AOPs treatment was higher than that of BPA,with BPA producing intermediates that exhibited the strongest acute toxicity in the UV/H₂O₂system,the inhibition rate of luminescent bacteria is as high as 81.1%.UV/PDS treatment of BPS produced intermediates with strong acute toxicity,the inhibition rate of luminescent bacteria is as high as 95.5%.DOM inhibited the photodegradation of BPA and BPS in all three systems,thereby reducing the production of more toxic intermediates.（3）Quantitative Structure-Activity Relationship（QSAR）model construction for degradation rate constants of phenolic pollutants in UV-AOPs systems:Based on the measured degradation rate constants of 19 phenolic pollutants in the three UV-AOPs systems,QSAR models were constructed using the multiple linear regression（MLR）method.The results showed that the difference in degradation rate constants between BPs and other phenolic compounds in different UV-AOPs systems was related to their molecular structures.The constructed QSAR models exhibited high fitness,robustness,and predictive ability.They can be used to quantitatively predict the degradation rate constants of other structurally similar pollutants in the three systems.In summary,this study compared and analyzed the kinetic differences between BPA and its substitute BPS in different UV-AOPs.It explored the impact of water environmental factors on degradation rate and evaluated the toxic effects of BPA and BPS degradation systems and by-products.The findings provide a theoretical basis for the practical application of AOPs in the treatment of bisphenol pollutant-contaminated wastewater.