Transformation Of Benzophenone UV-Filters In Chlorination,Chloramination And UV/Chlorination Conditions

Benzophenones(BPs)-type UV filters,a kind of high safety and inexpensive UV filters,are of great concern due to the widely used in cosmetics and personal care products.Furthermore,BPs-type UV filters would continually release into aquatic environments through washing,swimming,and some recreational activities.Most BPs-type UV filters are lipophilic,which may bioaccumulate,therefore,the elimination efficiency of traditional water treatment is quite low.Chlorine and chloamine are the most commonly used disinfectants in the world,disinfectants can not only kill pathogenic microorganisms,but also react with organic pollutants to form chlorinated disinfection by-products(DBPs),some by-products have been confirmed to be more toxic than their parents.BPs-type UV filters and their chlorinated products have frequently been detected in aquatic enviornments,but little studies are regarding their transformation pathway at swimming water conditions.This paper mainly focused on the kinetics,transformation pathyways and DBPs formation of the most widely used BP-type UV filters,which are 2-hydroxyl-4-methoxyl benzophenone(BP3)and 2-hydroxyl-4-methoxyl benzophenone-sulfonic acid(BP4)in chlorination,chloramination and UV/chlorination.In this study,the reaction between BP3,BP4 and chlorine,chloramine followed pseudo-first-order kinetics.BP3 is more active than BP4,and chlorine is much more effective than chloramine.The transformation products were detected by LC-MS,and the stability of transformation products followed the order of tri-chlorianted oxybenzone>di-chlorinated methoxyphenoyl>di-chlorinated oxybenzone>mono-chlorinated methoxyphenoyl>mono-chlorinated oxybenzone.DBPs including chloroform,trichloroacetic acid and dichloroacetic acid were quickly formed,and changed following the concentration of disinfectants and pH detected.The formation of three kinds of DBPs form chlrination or chloramination of BP3 were 3 times higher than that of BP4.The generation of chloroform gradually increased with pH from 7 to 11,under neutral conditions the generation of DCAA was greater than the acidic conditions,while there was little DCAA under alkaline condition,the generation of TCAA gradually decreased with pH from 4 to 11.Under the same condition,the chlorination kinetics constant of BP3 and BP4 were higher than that under UV/chlorine,but the formation of DCAA and TCAA in UV/chlorine were 3?4 times higher than that in chlorination.UV can rapidly degrade the free available chlorine to inhibit the degradation of BP3 and BP4.After the free chlorine is completely consumed,the formation of DBPs is dependent on UV.Moreover,BP3 or BP4 is not only used as a reactant,but also promote the DBPs formation as a photosensitizer.