Magnetic hydrothermal biochar for efficient enrichment of uranium(VI) by embedding Fe3O4 nanoparticles on bamboo materials from "one-can" strategy

Reasonable surface modification and increasing structural porosity were two key factors to improve the adsorption performance of biochar in the adsorption field. In this study, three different proportions of bamboo -based magnetic biochar modified with Fe3O4 (Fe3O4 @MBC) were synthesized by "one-can" method. BET showed that this method could effectively increase the specific surface area (129.79 m2 g-1) and VSM indicated Fe3O4 @MBC had an excellent magnetic response (32.84 emu g-1), which was conducive to the separation after adsorption. The accurate matching of pseudo-second-order kinetic model, thermodynamic model and Langmuir isotherm showed that at 298 K, pH = 4.5, the adsorption process dominated by chemical complexation and monolayer adsorption was spontaneous, endothermic and disordered. Saturated adsorption capacity of Fe3O4 @MBC with the more Fe3O4 loading proportion could reach 70.45 mg g-1 within 12 h. The loading of Fe3O4 by "one-can" method not only provided abundant Fe-O groups to assist adsorption, but also magnetized bamboo matrix. Results showed that adsorption mechanism of U(VI) by Fe3O4 @MBC included electrostatic action and chemical complexation involving Fe-O, carbonyl group and ample oxygen-containing functional groups. Therefore, Fe3O4 @MBC with easy separation, excellent regeneration, remarkable economic potential and green value provided a novel solution for the field of radioactive wastewater treatment.