Disinfection by-products formation during hypochlorination of isoproturon contaminated groundwater

An investigation has been carried out to identify the by-products formed during the disinfection by hypochlorite of water contaminated with isoproturon, one of the herbicides most used in Europe. The reaction of isoproturon with sodium hypochlorite (NaCIO) has been investigated in synthetic aqueous solutions, over 48h, in presence and in absence of interfering bromide ions, at room temperature, within the pH range 6-9, using two different (NaCIO)/(isoproturon) mass ratios: (40ppm)/(10ppm) and (3ppm)/(10ppb). When the effect of bromide ions was studied, (NaCIO):(Isoproturon):(Bromide) mass ratios were (40ppm):(10ppm):(20ppm) and (3ppm):(10ppb):(100ppb). By-products were detected by liquid chromatography and identified by HPLC-MS and GC-MS. The results indicated that: the higher the reagent concentrations the faster the reaction, the presence of bromides speeds up the reaction, pH does not influence the reaction, four and three identified isoproturon substitution by-products are formed in the absence and in the presence of bromides respectively.