Synthesis and characterization of tri-n-octyl phosphine oxide impregnated pyrolytic carbon for efficient extraction of uranium (VI) in strongly acidic solution

The development of adsorbents capable of separating uranium from uranium-containing wastewater involves critical research. In this study, a novel functional carbon material was successfully synthesized by impregnating tri-n-octyl phosphine oxide into the pyrolytic carbon (TOPO@PyC). This material exhibited fast adsorption rate (less than an hour), high adsorption capacity ( q m = 48.1 mg/g) and strong selectivity (98.8 %) for U(VI) under low to moderate acidic conditions. The pseudo-second-order kinetic model and Langmuir isothermal model effectively described the adsorption kinetics and equilibrium data, respectively. The SEM-EDS, FT-IR, XPS and DFT calculations revealed that U(VI) was successfully adsorbed by TOPO@PyC through complexation with P = O group in TOPO. Furthermore, the adsorption efficiency and desorption efficiency of TOPO@PyC remained above 95 % after five cycles, indicating that TOPO@PyC possessed excellent reusability. Consequently, with inertness of pyrolytic carbon and strong selectivity of TOPO, the TOPO@PyC material holds significant potential for the treatment of uranium-containing acidic wastewater.