Development of cellulose-based sorbent for uranium extraction from seawater

Abstract

Uranium dissolved in seawater has garnered attention as a potential new source of uranium, prompting extensive research on various sorbents for uranium extraction from seawater. Accurate performance evaluation of these seawater uranium sorbents necessitates advanced techniques for the quantitative analysis of trace uranium in seawater matrices. In this study, in light of impending regulations on marine plastic use, a uranium sorbent based on the biodegradable material cellulose was synthesized, and the performance of the sorbent was evaluated by quantifying trace dissolved uranium in seawater using time-resolved laser fluorescence spectroscopy (TRLFS). After synthesizing sorbents by functionalizing cellulose hydrogel and coconut fiber pulp with amidoxime groups, their properties were confirmed through attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and elemental analysis (EA). In synthetic seawater containing 3.1 ppb uranium, amidoxime-functionalized cellulose hydrogel (AO-cellulose) and amidoxime-functionalized coconut fiber pulp (AO-coir) exhibited high distribution coefficients (19.8 L/g and 1.7 L/g, respectively) and short half-saturation times (7.8 hours and 11.4 hours, respectively). The high sorption performance of AO-cellulose observed in this study suggests that biodegradable sorbents can be viable alternatives to existing plastic-based sorbents. The TRLFS-based quantitative analysis of uranium dissolved in seawater achieved a detection limit of 0.29 ppb, demonstrating the potential of TRLFS for easier and faster uranium analysis and facilitating future research on uranium sorption.