Influence of feedstocks and modification methods on biochar's capacity to activate hydrogen peroxide for tetracycline removal.

Three types of raw biochar (i.e. CBC, OBC, PBC produced from cornstalk, orange peel and peanut hull, respectively) and the modified ones (i.e., KMnO-, KOH- and HPO-treatment) were employed to activate HO for the removal of tetracycline (TC). The effects of pyrolysis temperatures, HO concentration and initial pH were examined. TC removal by raw biochars w/o HO was dependent on the feedstock and pyrolysis temperature of biochar, but the removal efficiency was still quite low under optimum conditions. The KMnO-treatment significantly enhanced the adsorption of TC on all three biochars, but only enhanced the TC removal by CBC + HO. The KOH-treatment had insignificant effect on the adsorption of TC on biochar, but improved the performance of CBC/PBC + HO. The HPO-treatment had a negative impact on TC removal by biochar w/o HO. Overall, HO could either enhance or decrease the TC removal by biochar, depending on biochar type, HO concentration and solution pH.