Ultrasound And Heat Activated Persulfate For The Degradation Of Bisphenol S In Water

Bisphenol-S?BPS?,considered as a“safer”alternative to Bisphenol-A?BPA?,have gradually gained attention by water treatment researcher due to it shares the similar dilemma of endocrine disruption.In recent years,advanced oxidation processes that based on perdisulfate?persulfate,PDS or PS?gained extensive research because sulfate radical can be generated by the activation of persulfate and oxidize organic compounds quickly.PDS was stable under normal circumstances and need to be activated for organic compounds degradation.But the great mass of researchers aim at the study of activation methods and the degradation of pollutants.Therefore,profound understandings of PDS reaction kinetics after actvation and mechanism of PDS activation method were meanful for application of advanced oxidation processes that based on perdisulfate in water treatment.In this text,firstly,the degradation of BPS in thermo-activated persulfate?TAP?were studied detailedly,and the orders of reaction of BPS and PDS were explored,besides,the various operating conditions effects on BPS degradation were evaluated.Secondly,the research put emphasis on the ultrasonic activation of persulfate?US/PDS?which shares similar activation mechanism with TAP.Exploring the difference of PDS and BPS reaction kinetics in US/PDS and TAP respectively,and then deduce the mechanism of US/PDS.Moreover,the influences experimental operating conditions on the BPS degradation in US/PDS were assessed as well.In the last,intermediate products respectively in TAP and US/PDS were identified,and then possible reaction pathways were proposed.In TAP system,in order to accurately describe the reaction orders,a improved demisemi-lives method was proposed and then acquired the reaction orders of BPS and PDS.The results revealed that the oxidation rate of BPS could be expressed by the kinetic rate equation:-d[BPS]/dt=(2.39210^-4 mM^-0.1 min^-1)[BPS]⁰[PS]^1.1.Pseudo-zero-order mode and demisemi-lives method were applied to compute the pseudo-zero-order rate constant and obtain the value of the activation energy?Ea?of BPS in TAP system.The Ea is 112.9±6.8kJ2mol^-1,which is lower compared to its counterpart calculated from pseudo-first-order mode.Besides,the effects of initial pH,humic acid?HA?,coexisting inorganic anions(i.e.,carbonate/bicarbonate(CO₃^2-/HCO₃^-),nitrate ions?NO₃^-?,chloride ions?Cl^-?)and radical scavenger?i.e.,methyl alcohol?MeOH?and tertiary butanol?TBA??on BPS degradation were evaluated.Cavitation bubble formed in the ultraphonic condition was the centaral site of oxidation or actvation reaction.Therefore,the degradation kinetics of BPS in US/PDS system was different from TAP system,and shown heterogeneous characteristics.The increase of initial BPS concentration speed up it`s degradation rate?non-zero order?.And the more PDS accelerate the BPS degradation,but it`s reaction orders was lower in US/PDS system than its counterpart in TAP system.The BPS degradation rates were described exactly by the Langmuir heterogeneous adsorption model.Modelling the activation reaction of PDS and explaining it by the Langmuir heterogeneous adsorption model,the results reveal that the model coincided with the activation reaction rule well.The equilibrium constant of PDS in the US system far below that of BPS,which may due to the formation of supercritical water around the cavitation bubble.Therefore,the PDS activated by US alone may not a wise choice in practice.Besides,the effects of pH,CCl₄,Zero-valent copper and dissolved oxygen on the BPS degradation in US/PDS system were studied,and the formation and quantitation of hydrogen peroxide and hydroxyl radical were explored.In the TAP system,oxidation of BPS was initiated by abstracting an electron at first,forming BPS radicals,then these radicals react with each other and thereafter produce two resultant dimers by carbon-carbon?C–C?and carbonoxygen?C–O?coupling,these intermediate products were mineralized by further oxidation at last.In the US/PDS system,the degradation of BPS has three routes,namely,radical polymerization,generated the dimers as that in TAP system,hydroxyl radical oxidation,the representative product was hydroxyderivativeofBPS,hydrolysis,therepresentativeproductwas p-hydroxybenzenesulfonic acid.