A new technology developed for the treatment of industrial wastewater makes it possible to separate salt and heavy metals in a single process. The Electrochemical Ion Pumping (EIP) system, developed by researchers from Rice University and Vanderbilt University, cleans industrial wastewater while also enabling the recovery of high-purity metals. According to the researchers, the method offers a more efficient alternative to existing techniques.
Salt and Metal Treatment with a Single System
Wastewater generated in sectors such as electronics manufacturing and metal processing contains high amounts of dissolved salts and toxic heavy metals. Currently, multiple treatment methods are often used to remove these pollutants. Reverse osmosis, preferred for salt removal, leaves behind a concentrated saline waste that is difficult to reuse. The removal of heavy metals is carried out using chemical agents, resulting in the formation of a hazardous type of sludge.
The EIP platform developed by researchers combines these two processes into a single electrochemical system. The system uses special electrodes to extract dissolved ions from the wastewater and transfer them to a second flow line. This way, both salt removal and metal separation occur within the same process.
In traditional systems, the feed and receiving solutions need to be continuously changed to capture and release ions. The new EIP approach eliminates the need for this physical change. Instead, rapid changes in the electrical circuit ensure that ions move continuously in a single direction within the system.
The research team can precisely control the voltage on the electrode surface to program which ions will be captured. When high voltage is applied, the system performs only salt removal, and both salt and copper ions pass into the receiving stream. When the voltage is lowered just below the electrochemical reaction threshold of copper, the electrode selectively accumulates copper ions on its surface while allowing salts to pass through.
85% Salt and 92% Heavy Metal Removal in Four Hours
In experiments with synthetic wastewater, the system removed 90% of the salt in the environment while collecting almost all of the copper on the electrode. In a more challenging scenario, researchers tested a mixture containing copper, nickel, and sodium. Using a five-electrode setup, the team successfully separated copper selectively by adjusting the voltage, while allowing nickel and sodium to pass through the system.
After just four hours of treatment, 85% of the salt and over 92% of heavy metals like copper and nickel were removed from the environment. Furthermore, the copper accumulated on the electrode was found to reach 96% purity compared to nickel.
Thanks to this technology, facilities will not only be able to make their wastewater suitable for reuse but also recover high-purity copper directly from the treatment equipment. Researchers emphasize that this approach could transform industrial saline wastewater from merely a disposal burden into an economically valuable mineral resource.
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