Spontaneous electrochemical uranium extraction from wastewater with net electrical energy production

Extracting uranium from uranium mine wastewater is highly important from both the environmental protection and the resource preservation perspectives. However, conventional adsorption methods and zero valent iron-induced reductive precipitation methods have intrinsic limitations. Here we propose a spontaneous electrochemical method that spatially decouples the uranium–adsorption–reduction reactions and the iron oxidation reaction, enabling stable and efficient uranium extraction with net electrical energy output. U(VI) species are firstly adsorbed on a carbonaceous electrode, and subsequently reduced by electrons derived from iron oxidation. Using simulated wastewater, the spontaneous electrochemical method achieves 12-fold higher uranium extraction efficiency in comparison with the adsorption method. Using real wastewater, the uranium extraction efficiency reaches 303 mg g −1 upon 60 h operation with simultaneous net electrical energy production of 0.65 Wh m −2 with an operating cost of only USD 3.94–6.94 per kg of U. This work can pave a new avenue for cost-effective uranium recovery from mine wastewater.