An Efficient Strategy for Enhancing the Adsorption Capabilities of Biochar via Sequential KMnO4-Promoted Oxidative Pyrolysis and H2O2 Oxidation

In this study, sequential KMnO4-promoted oxidative pyrolysis and H2O2 oxidation were employed to upgrade the adsorption capacities of durian shell biochar for methylene blue (MB) and tetracycline (TC) in an aqueous solution. It was found that the KMnO4/H2O2 co-modification was greatly influenced by pyrolysis temperature and the optimal temperature was 300 °C. Moreover, a low concentration of H2O2 enabled the improvement of the adsorption capabilities greatly with the catalysis of pre-impregnated manganese oxides, addressing the shortcoming of single H2O2 modification. The co-modified biochar exhibited high adsorption capabilities for MB and TC, remarkably surpassed KMnO4- and H2O2- modified biochars as well as pristine biochar. The increase of adsorption capabilities could be mainly contributed to the incorporation of MnOx and carboxyl by KMnO4-promoted oxidative decomposition and Mn-catalyzed H2O2 oxidation. This would provide a novel and efficient method for preparing highly adsorptive biochar using sequential KMnO4-promoted oxidative pyrolysis and H2O2 oxidation.