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., KMnO4-, KOH- and H3PO4-treatment) were employed to activate H2O2 for the removal of tetracycline (TC). The effects of pyrolysis temperatures, H2O2 concentration and initial pH were examined. TC removal by raw biochars w/o H2O2 was dependent on the feedstock and pyrolysis temperature of biochar, but the removal efficiency was still quite low under optimum conditions. The KMnO4-treatment significantly enhanced the adsorption of TC on all three biochars, but only enhanced the TC removal by CBC + H2O2. The KOH-treatment had insignificant effect on the adsorption of TC on biochar, but improved the performance of CBC/PBC + H2O2. The H3PO4-treatment had a negative impact on TC removal by biochar w/o H2O2. Overall, H2O2 could either enhance or decrease the TC removal by biochar, depending on biochar type, H2O2 concentration and solution pH.