Reaction of benzophenone UV filters in the presence of aqueous chlorine: Kinetics and chloroform formation

► The transformation of two UV filters was examined in the presence of excess aqueous chlorine. ► The kobs was dependent on the concentrations of HOCl and UV filter phenolate form, which vary with pH. ► Meta-methoxy and -OH groups act similarly for phenolic moieties and reactivity towards HOCl. ► Maximum chloroform/UV filter yields were 0.302 CHCl3/OXY at pH 6 and 0.321 CHCl3/DiOXY at pH 10. ► UV filters are an important precursor to chloroform formation in immersion water.