Preparation of amidoxime-based ultra-high molecular weight polyethylene fiber for removing uranium from fluorine-containing wastewater

[Background] During the uranium enrichment process, the generated wastewater containing fluoride and uranyl ions, has potential threat to aquatic ecosystem and human health. Thus, the uranium concentration in the wastewater and its secondary sources must be reduced to an acceptable value before being discharged into the environment. [Purpose] This study aims to graft acrylonitrile (AN) and methacrylic acid (MAA) onto ultra-high molecular weight polyethylene (UHMWPE) fiber to synthesize amidoxime (AO)-based sorbent for removing uranium (U (VI)) from simulated wastewater containing fluoride ions. [Methods] The AO-based sorbent was prepared by radiation grafting of AN and MAA onto UHMWPE fiber, followed by amidoximation. The chemical structures and surface morphologies of the pristine and modified UHMWPE fiber were characterized by Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The uranium adsorption performance of the sorbent was investigated by batch adsorption in simulated wastewater. [Results and Conclusions] 1) The uranium sorption kinetics and isotherm of AO-based UHMWPE fiber were in congruence with the pseudo-second-order model and the Langmuir model, respectively. 2) The maximum U (VI) adsorption capacity in simulated wastewater (U (VI): 40 mg · L^-1; sodium fluoride (NaF): 10g · L^-1; sorbent dosage: 0.2 g · L^-1; time: 21 d) was 151.98 mg · L^-1, which is basically consistent with the theoretical saturated adsorption capacity (153.85 mg · L^-1). 3) The removal ratio of U (VI) in simulated wastewater reached 99.93% by increasing sorbent dosage (1.5 g · L^-1), and the residual uranium (28 μg · L^-1) can meet the national discharge standard (< 50 μg · L^-1). (authors)