Bromate formation in bromide-containing waters irradiated by gamma rays

摘要

The formation of bromate,a classified potential carcinogen,is of great concern when disinfection processes are used for treating high-bromide drinking waters.Bromide-containing aqueous solutions with various additives were irradiated by ^(60)Co γ source.With a 2.0 kGy irradiation of N_2O-saturated solutions at initial bromide concentrations of 180.2μgl^(-1),416.9μgl^(-1),663.1μgl^(-1) and 823.9μgl^(-1).79.5%,84.0%,87.3%and 88.3%of bromide ions were transformed to bromate,respectively.Addomg CO_3^(2-)/HCO_3^- or NO_3^- ions into N_2Osaturated bromide solutions,the amount of bromate ions formed decreased with increasing concentrations of the additives.On the other hand,the bromate concentration was all below the detection limit of 1 μgl^(-1) whenever N_2O was not added to quench e_(aq)^- and H.The results indicated that γ-rays irradiation could be used as a disinfection process,instead of ozonation,to comply with upcoming more stringent regulations,especially in waters containing high concentrations of bromide.