Hydrophilically reinforced amidoxime based fiber for selective uranium recovery from seawater

The estimated amount of uranium dissolved in seawater is about 4.5 billion tons, which is 1000 times more than the terrestrial sources. Efficient uranium extraction from sea water has drawn increased attention due to the growing demand of nuclear fuel. Owing to the extremely low concentration of uranium (~3.3 ppb) in seawater and the presence of other competing ions at much higher concentrations, current technically feasible recovery processes are not economically possible on a large scale. In this work, several poly(amidoxime) grafted fiber adsorbents will be prepared. These adsorbents will have high degree of grafting to improve the uranium extraction capacity. The amidoxime functional groups in the adsorbents will be in open- chain form dominantly to ensure high uranium selectivity. The adsorbents in fiber form will be readily deployable. In Phase I, a series of poly(amidoxime) grafted fiber adsorbents will be prepared. More than 10 g of each adsorbent will be obtained. These fiber adsorbents will have high uranium extraction capacity, which will be at least 3 times higher than the JAEA (Japan Atomic Energy Agency) reference fiber. High uranium selectivity is also expected for these adsorbents, especially uranium/vanadium selectivity will be greater than 2, improved from 0.1 of our current fiber adsorbents. The adsorbents will retain 70-80% of their uranium extraction capacity after undergoing at least 10 adsorption-elution cycles. Our ultimate goal is to develop a deployable device that can be mounted under marine vessel for selective extracting uranium from seawater effectively and continuously. The device will contain fiber adsorption material (developed in Phase I) encapsulated in a prototype device (developed in Phase II) and can be attached to marine vessel for uranium extraction (developed in Phase III). Currently, several ocean tests showed the costliest part during uranium extraction from ocean comes from the operational cost, which will require a continuous seawater current bathing the adsorbent to speed up the extraction process. Our approach will greatly reduce the operational cost and make seawater uranium extraction economically feasible.