Phosphate-Based Ultrahigh Molecular Weight Polyethylene Fibers for Efficient Removal of Uranium from Carbonate Solution Containing Fluoride Ions

This work provides a cost-effective approach for preparing functional polymeric fibers used for removing uranium (U(VI)) from carbonate solution containing NaF. Phosphate-based ultrahigh molecular weight polyethylene (UHMWPE-g-PO(4)) fibers were developed by grafting of glycidyl methacrylate, and ring-opening reaction using phosphoric acid. Uranium (U(VI)) adsorption capacity of UHMWPE-g-PO(4) fibers was dependent on the density of phosphate groups (D(PO), mmol∙g(−1)). UHMWPE-g-PO(4) fibers with a D(PO) of 2.01 mmol∙g(−1) removed 99.5% of U(VI) from a Na(2)CO(3) solution without the presence of NaF. In addition, when NaF concentration was 3 g∙L(−1), 150 times larger than that of U(VI), the U(VI) removal ratio was still able to reach 92%. The adsorption process was proved to follow pseudo-second-order kinetics and Langmuir isotherm model. The experimental maximum U(VI) adsorption capacity (Q(max)) of UHMWPE-g-PO(4) fibers reached 110.7 mg∙g(−1), which is close to the calculated Q(max) (117.1 mg∙g(−1)) by Langmuir equation. Compared to F(−), Cl(−), NO(3)(−), and SO(4)(2)(−) did not influence U(VI) removal ratio, but, H(2)PO(4)(−) and CO(3)(2)(−) significantly reduced U(VI) removal ratio in the order of F(−) > H(2)PO(4)(−) > CO(3)(2)(−). Cyclic U(VI) sorption-desorption tests suggested that UHMWPE-g-PO(4) fibers were reusable. These results support that UHMWPE-g-PO(4) fibers can efficiently remove U(VI) from carbonate solutions containing NaF.