Amidoxime-modified ultrathin polyethylene fibrous membrane for uranium extraction from seawater

Abstract

The amidoxime-modified ultrathin polyethylene fibrous membrane (called as AFM) is prepared by a two-step graft polymerization method. The nano-sized particle structures are constructed on the AFM adsorbents surface after grafting. The adsorption behaviors of AFM adsorbent are studied by laboratory scale adsorption experiments. The adsorption results show that the adsorption of uranium by AFM is an endothermic spontaneous behavior without additional driving force. The AFM absorbent shows high specific surface area, good mechanical property and outstanding reusability of >12 cycles. Furthermore, the AFM adsorbent has a high uranium adsorption capacity of 147.38 mg/g in 8 ppm U-spiked simulated seawater for 96 h and 7.46 mg/g in natural seawater for 56 days. The results show that the degree of grafting (DG) and thickness of the membrane are the two key factors affecting the adsorption capacity. The adsorbent with thinner membrane thickness has a higher adsorption capacity at a moderate DG. This is because at moderate DG, the thinner the membrane is, the easier the adsorption sites are contacted by uranium ions. This work presents a novel membrane adsorbent with high uranium adsorption capacity and long service life, which shows significant application potential for uranium extraction from seawater.