Simultaneous Desalination and Selective Metal Recovery Enabled by Potential-regulated Electrochemical Ion Pumping

Industrial wastewaters with both high salinity and heavy metals are common, yet no existing process can achieve desalination and metal recovery in integrated technology platform. Conventional desalination processes do not distinguish background electrolyte generate toxic brines with heavy metals and miss the opportunities for resource recovery. In this work, we show that electrochemical ion pumping (EIP) has the unique feature to enable simultaneous desalination and metal recovery through programmable control of electrode potential. Because EIP transfers only a small amount of ions per half-cycle via high-frequency circuit switching, the electrode potential can be maintained within a narrow window throughout operation, which allows redox reactions to be selectively activated or suppressed without interrupting continuous ion transport. At potentials above the Cu²⁺/Cu reduction threshold, the system desalinates only capacitively with no metal deposition. Shifting the potential window below this threshold triggers selective copper electrodeposition on the electrode while performing desalination. In an asymmetric five-electrode EIP stack fed with a mixture of Cu²⁺, Ni²⁺, and Na+, positioning the potential window between the reduction potentials of the two metals yielded selective Cu²⁺ capture on the electrode. These findings establish electrode potential as a controllable operation parameter, providing an integrated platform for coupled water recycling with selective resource recovery from complex industrial brines.