Polymer/biomass-derived biochar for use as a sorbent and electron transfer mediator in environmental applications

[Display omitted] •Co-pyrolysis of polymer and rice straw improves the properties of biochar.•Polymer/rice straw-derived biochar enhances the sorption of DNT and Pb.•Increasing aromaticity and hydrophobicity account for the sorption of DNT.•The sorption of Pb is attributed to increasing CEC, pH, and surface area.•Catalytic role of biochar remains after co-pyrolysis of polymer and rice straw. Co-pyrolysis of polymer and biomass wastes was investigated as a novel method for waste treatment and synthesis of enhanced biochar. Co-pyrolysis of rice straw (RS) with polypropylene (PP), polyethylene (PE) or polystyrene (PS) increased the carbon content, cation exchange capacity (CEC), surface area and pH of the biochar. As a result, the sorption of 2,4-dinitrotoluene (DNT) and Pb to polymer/RS-derived biochar was markedly enhanced. The increased aromaticity and hydrophobicity may be responsible for enhancing the DNT sorption to the polymer/RS-derived biochar. In contrast, increasing CEC, higher pH, and the newly developed surface area may account for the enhancement in Pb sorption. The addition of polymer to RS did not significantly change the catalytic role of biochar during the reduction of DNT by dithiothreitol. Our results suggest that co-pyrolysis of RS and polymer can improve the biochar properties to enhance the sorption of DNT and Pb.