Sorption of Nitro Explosives to Polymer/Biomass-Derived Biochar

Factors affecting the sorptive removal of nitro explosives (2,4,6-trinitrotoluene [TNT] and hexahydro-1,3,5-trinitro-1,3,5-triazine [RDX]) to polymer/biomass-derived biochar were investigated through batch experiments. Compared with that of rice ( L.) straw (RS)-derived biochar, the sorption of TNT and RDX to polymer/RS-derived biochar was greatly enhanced by >2.5 and 4 times, respectively. The type and amount of polymer did not significantly affect the sorption of nitro explosives to polymer/RS-derived biochar. Pyrolysis temperature did not affect the sorption capacity. Surface treatment with acid or an oxidant did not significantly change the sorption capacity, suggesting that polymer residues may be strongly responsible for the enhancement. Possible polymer residues were identified via gas chromatography mass spectrometry analysis. The toxicity characteristic leaching procedure and Microtox bioassay analyses indicated that polymer/RS-derived biochar did not show possible harmful effects. Our results suggest that polymer/RS-derived biochar can be effectively used as a sorbent to remove nitro explosives both in the natural environment and engineered systems.