the effect of nitrate as a radical scavenger for the removal of humic acid from aqueous solutions by electron beam irradiation

introduction: humic acids have adverse effects on the water quality, then should be removed from water resources. the aim of this study was to evaluate the effect of nitrate as a radical scavenger for removal of humic acid from aqueous solutions by electron beam irradiation. materials and methods: in this study, after preparation of stock humic acid solution in alkaline condition, different concentrations of humic acid (10, 25 and 50 mg/l) were prepared. different concentrations of nitrate (25, 50 and 100 mg/l) added to humic acid samples and then absorption of samples was measured at 254 nm by using uv-vis spectrophotometer before and after the electron beam irradiation. this study has done at ph= 8 and at different electron beam adsorbed dose of 1, 3, 6, 9 and 15 kgy. results: the results of this study showed that the increasing of adsorbed dose from 1 to 15 kgy, the removal efficiency of humic acid also increased. by increasing of nitrate concentration from 25 to 100 mg/l, the removal efficiency of humic acid has decreased from 43.8% to 36.6% and nitrate acts as a radical scavenger. by increasing of humic acid concentration from 10 to 50mg/l, removal efficiency decreased in all adsorbed doses. kinetic analysis of our results showed that the results well fitted with the second - order reaction. conclusion: we can conclude from this study that electron beam irradiation could be a useful process for the treatment of natural organic matter (humic acid) from surface waters.