Highly efficient uranium extraction by aminated lignin-based thermo-responsive hydrogels

In this work, triethylenetetramine (TETA) functional lignin (AL) has been prepared, and the aminated lignin-based thermo-responsive (AL-PNIPAM) hydrogels were prepared by radical polymerization. AL-PNIPAM hydrogels exhibited a satisfactory adsorption performance for uranium aqueous solution, with a maximum uranium adsorption capacity of 285.5 mg·g−1 at 298 K. The study of adsorption kinetics showed that the adsorption model of AL-PNIPAM hydrogels was more consistent with pseudo-second-order kinetic equation, confirming the prominent chemical adsorption of the adsorption process. More importantly, it showed high selectivity towards uranium (VI), and the Kd was 3.82 × 105 mL·g−1 in simulated seawater. And uranium (VI) can be effectively desorbed, the best desorption was achieved at 15 °C using dilute nitric acid solution with a maximum resolution efficiency of 76 %. Therefore, AL-PNIPAM hydrogels could be considered as a potential candidate in the field of uranium extraction from seawater.