Ultrafast uranium recovery from high-salinity nuclear wastewater using amine-functionalized lignin microspheres

U(VI) recovery from high-salinity nuclear wastewater remains a diffcult challenge. Accordingly, amine-functionalized lignin microspheres (AL-PEI/GMS) with high porosity, abundant functional groups, and appropriate surface area, were synthesized via a green and simple process, and used as an adsorbent for U(VI) recovery. Results illustrated that AL-PEI/GMS showed outstanding adsorption capacity for U(VI) of 250 mg/g and high selectivity of SF U(VI)  > 15, 000 over a wide pH range from one to nine, preeminent regeneration performance with adsorption efficiency > 95% after 50 cycles, and desorption performance (desorption efficiency > 60% after 50 cycles). The high applicability of AL-PEI/GMS was further proven by its high U(VI) removal efficiency under various high-salinity conditions (U(VI) removal rate > 99%). Furthermore, 2553 bed volumes (BV) of the U(VI) feeding streams can be effectively treated by AL-PEI/GMS via a fixed-bed column system with an extremely high flow rate (20 mL/min), and more than 95.6% of U(VI) can be rapidly desorbed by using 12 BV of eluent solution. Furthermore, the comparatively low operational costs and overall economic feasibility further suggested the great potential of AL-PEI/GMS for U(VI) on the industrial scale. The mechanism of U(VI) adsorption on AL-PEI/GMS was further found to be chemisorption-related. This work presents an applicable approach by using amine-functionalized lignin microspheres to achieve highly ultrafast U(VI) adsorption and desorption under a high-salinity condition via a fixed-bed column system, which not only provides a feasible method to purify U-contaminated nuclear wastewater, but also successfully realizes the recycling of U(VI) from nuclear wastewater, thus resolving the increasingly serious energy crisis and protecting environment in the nuclear industry.