Phosphate-functionalized mesoporous carbon for efficient extraction of uranium (VI)

A simple approach for preparing high-efficiency and cost-effective adsorbent to extract uranium in nuclear wastewater is essential for safeguarding the environment. This study introduces an easy procedure to synthesize phosphate-rich biochar (PS) from sawdust by treating it with phosphoric acid before carbonization (700 °C). The sample was characterized by SEM, FT-IR, BET and XPS, indicating that the PS700 exhibited a high concentration of phosphorous groups, high specific surface area and developed mesoporous structure. Subsequently, the effects of pH (optimal at pH 7), adsorption kinetics (fitted by quasi-second-order), and sorption isotherms (modeled by Langmuir) were investigated. The best uranium (VI) adsorption performance of PS700 is 808 mg g −1 at 40 °C and pH 7. In addition, PS700 shows remarkable selectivity and recyclability for uranium (VI). The sorption mechanism can be attributed to the uranium (VI) binding with phosphate groups on the surface of sorbent, which significantly improve its ability for uranium (VI) adsorption. This study displays a great application prospect of PS700 as innovative adsorbent for the efficient extraction of uranium (VI) from nuclear wastewater.