Low-cost reed straw-derived biochar prepared by hydrothermal carbonization for the removal of uranium(VI) from aqueous solution

Uranium is the important nuclear fuel and its effective adsorption using low-cost materials is meaningful to environmental protection and sustainable development of nuclear energy. In this study, green and economical reed straw-derived biochar (RBC) was prepared by hydrothermal carbonization method using low-cost reed straw as feedstocks and citric acid as catalysts for uranium(VI) removal. RBC possessed larger pores and more oxygen-containing functional groups, providing more abundant adsorption sites for uranyl ions. RBC adsorbed uranium pH-dependently, spontaneously and endothermically, and pseudo-second-order kinetics and the Langmuir model could adequately describe the adsorption process. This work highlighted a feasible synthesis strategy of biochar for radioactive contaminants removal.