Level 4 Milestone Report (PNNL-26418) – Temperature Effects on the Adsorption Capacity of Uranium and Vanadium on Amidoxime-Based Polymeric Fiber Adsorbents in Natural Seawater

Abstract

The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL’s Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the activities of the marine testing program was to determine how seawater exposure temperature effects adsorption capacity and adsorption kinetics for amidoxime-based polymeric adsorbents prepared by Oak Ridge National Laboratory. The deliverable for this milestone report is a manuscript currently being submitted for publication to the peer-reviewed journal Chemical Communications, a journal which is part of the Royal Society of Chemistry. Chemical Communications has a high impact factor (6.567 as of 4-25-2017) and also has a limited publication format of 4 pages. Hence, a significant amount of the information obtained in this study appears in a supplemental information section which is included along with the main body of the submission. The abstract from the manuscript submission is given below. The apparent enthalpy and entropy of the complexation of uranium (VI) and vanadium (V) with amidoxime ligands grafted onto polyethylene fiber was determined using time series measurements of adsorption capacities in natural seawater at three different temperatures. The complexation of uranium was highly endothermic, while the complexation of vanadium showed minimal temperature sensitivity. Amidoxime-based polymeric adsorbents exhibit significantly increased uranium adsorption capacities in warmer waters.