High-efficiency electrochemical uranium extraction from seawater enabled by Fe-involved coordination modification strategy

Abstract

The uranium extraction from seawater is crucial for sustainable nuclear energy but remains challenging due to its low concentration, carbonate competition, and energy-intensive processes. In this study, we developed and systematically evaluated a novel electrode material, CF@MTPN, coupled with an energy-efficient double potential step technique (DPST).CF@MTPN was fabricated by sequentially self-assembling iron-tannic acid (Fe-TA) networks and iron-phytate (Fe-PA) complexes on a carbon felt substrate. In simulated seawater (5 mg L -1 uranyl, 2 mM Na2CO3, pH 8.1), CF@MTPN achieved high uranium removal efficiencies of 90.3% using potentiostatic technique (PST) and 93.3% using DPST within 15 min, corresponding to 96.12 mg g -1 d -1 and 99.31 mg g -1 d -1 , respectively. Notably, by suppressing the competing hydrogen evolution reaction, DPST achieved a Faradaic efficiency 4.3 times higher than that of PST. It is noteworthy that although the DPST-induced current oscillations caused phytate hydrolysis in the Fe-PA layer of the control electrode (CF@MPN), the inner Fe-TA layer in CF@MTPN effectively mitigated this stability issue, thereby ensuring structural integrity. The practical viability was confirmed through a continuous-flow experiment using 20 L of natural seawater, which yielded a uranium recovery of 60.0 μg. This work presents a synergistic material and process solution for efficient, stable, and energyconscious uranium extraction from seawater.