Bromate reduction by granular activated carbon

Batch experiments were conducted to evaluate the kinetics of reducing bromate to bromide by granular activated carbon.Solution conditions were studied in details,such as pH,ionic strength,temperature and initial bromate concentration.The results showed the removal capacity of GAC was positively relevant to surface basic functional groups.The whole process was inhibited by other anions in solution and the inhibition sequence was NO~-_3 SO~(2-)_4 Cl~-.Pseudo-second order rate equation and intraparticle diffusion model were applied to fit the process of bromate reduction and the process of bromide formation,respectively,with regression coefficients higher than 0.97 at most cases.Bromate removal was found to be favored under conditions with low pH value and low ionic strength.Both sorption rate of bromate and formation rate of bromide were decreased,and then increased along with the increase of temperature during 15～42℃.In this experiment,the maximum adsorption capacity of GAC is 769.23(μmol/g)(98.4 (mg/g)),whereas the sorption process is slow and easily influenced.It is concluded that the sorption of bromate by the micropore portion of GAC was influenced by the release of bromide.