Electrochemical Desalination–Concentration Strategy Facilitating Uranium Extraction from Saline Solution

Efficient uranium recovery from low-grade sources such as seawater, salt lake water, and industrial wastewater is challenged by low content and the presence of competing salts. This work presents an integrated strategy combining osmotic membrane distillation (OMD) with alkaline water electrolysis (AWE), in which the OMD concentration process operates without additional external energy input by leveraging the AWE system for draw-solution regeneration. By using the AWE electrolyte as the osmotic solution, the integrated system concentrated uranium from 2.9 ppb to 45.2 ppm under salt-free conditions without external energy input. To address the detrimental effects of salinity, a modified selective electrodialysis device operating at a low applied cell voltage (<0.5 V) was developed to reduce salt concentration and mitigate osmotic pressure decline. A concentration–desalination–concentration cascade system was subsequently established, successfully concentrating uranium from 3.3 to 178.3 ppm in the presence of NaCl. Preconcentration significantly enhanced subsequent adsorption performance, increasing the adsorption rate by a factor of 11.4 and the adsorption capacity by a factor of 17.3, thereby overcoming the kinetic limitations typically associated with low uranium content sources. This integrated approach offers a promising pathway for recovering unconventional uranium resources while synergizing energy production with environmental remediation.