A novel phosphorylated hyper-crosslinked porous polymer for efficient uranium adsorption in water

As the nuclear resource industry rapidly progresses, efficient adsorbents play a vital role in separating and eliminating uranium from aqueous solutions. Herein, 9,9-dimethyl-fluorenylphosphonic acid was designed as a phosphate functional monomer and the triptycene as a rigid backbone monomer. Through the “knitting” strategy, a novel triptycene-based phosphorylated hyper-crosslinked porous polymer (TPP-DFP) was obtained by the above monomers. The resulted polymer TPP-DFP has a high BET surface area of 1397.62 m2/g with a rich porosity. The porous polymer TPP-DFP was the first time used for uranium adsorption from water and showed outstanding adsorption performance. The maximum uranium adsorption capacity of TPP-DFP was 414.26 mg/g, which was higher than that of most of other porous adsorbents. In the presence of impurity ions such as Ca2+, Mg2+, Al3+, Co2+, Ni2+, V5+, NO3−, CO32− etc., TPP-DFP exhibited high selectivity (Su up to 99%) for uranium. In addition, TPP-DFP has excellent reusability, and the removal percentage of uranium can reach more than 95% after 5 adsorption–desorption cycles. According to the XPS experiment, the mechanism of interaction between TPP-DFP and U(VI) was mainly due to the complex formed by the phosphate functional groups and U(VI). The theory DFT calculation indicated a 1:2 ratio of U(VI) and phosphate functional group on the two-distinct graft chain, which was consistent with the experimental results. Accordingly, the “knitting” polymerization technique showed potential for preparation effective adsorbents for uranium extraction from water.