Illinois researchers demonstrate electrochemical method for nitrate removal

Researchers from The Grainger College of Engineering have proposed a low-cost, easily regenerating method for removing nitrate from wastewater. 

An essential component of wastewater treatment is the targeted removal of contaminants like nitrate, a toxic compound found in agricultural runoff. Selective nitrate capture is essential for ensuring safe drinking water and supporting resource circularity. However, this type of targeted removal can be challenging because of nitrate’s difficulty in separating from chloride, a commonly co-occurring but innocuous ion that is similar in size and charge.

To address this challenge, researchers from The Grainger College of Engineering and the College of Liberal Arts & Sciences at the University of Illinois Urbana-Champaign created a new “smart” material capable of high nitrate selectivity. Their findings, published in Nature Communications, report a record-setting selectivity for electrochemically active materials for nitrate removal, and introduce an adsorption process that requires no chemical input.

“What we’ve created is basically an easily cleanable, easily regenerable sponge for nitrate capture,” said Xiao Su, an associate professor of chemical and biomolecular engineering and senior corresponding author of the paper.

With collaboration from Roland Cusick, associate professor of civil and environmental engineering, and teams from Oak Ridge National Laboratory, Lawrence Livermore National Laboratory, and the University of Leicester, the cross-disciplinary team began their initiative by building upon previous work from the Su group that used polymers to convert nitrate to ammonia. After struggling to capture sufficient nitrate with their initial method, Su and his collaborators reworked the problem by capitalizing on one subtle difference between nitrate and chloride: their solvation properties.

Appealing to nitrate’s slightly more hydrophobic character, the researchers designed new selective polymers with increased hydrophobicity. Like metal shavings drawn to a magnet, nitrate’s attraction to the revamped polymers resulted in a selective adsorption effect that separated its ions from chloride. Importantly, the attraction could be turned off by electrochemical control of the conducting polymers, and the nitrate could be released, with the adsorbent regenerating easily.

The new and improved approach is more cost-effective than existing commercial wastewater treatment processes, which rely on adsorption techniques to dilute contaminants. Analysis from the wastewater treatment model run by Cusick’s lab revealed a 50% reduction in costs for the proposed system when compared to traditional methods.

“This technology has a chance to really revolutionize the way things are done in water treatment,” Su said.

Although the Illinois Grainger engineers’ method has been validated in real wastewater conditions, their next goal is to scale up the process for commercial use with the help of industry partners. Additionally, Su’s group is working on electrocatalytic methods for converting the extracted nitrate waste to ammonia.

“This is an ongoing project that our whole team has been working on for over three years,” Su said. “A lot of work has gone into not only creating these materials but trying to understand the process at multiple scales. This was a unique team effort that combined synthesis and characterization as well as molecular and process modeling, which makes the results exciting from both a fundamental and applied perspective.”

This work was supported by the National Alliance for Water Innovation (NAWI), funded by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy Advanced Manufacturing Office under Funding Opportunity Announcement DE-FOA-0001905, through Project 6.16. “Redox-Mediated Electrodes for the Precision Separation of Nitrogen and Phosphorus Oxyanions.”

Co-authors and contributors to the work include Ching-Yu Chen and Riccardo Candeago of the Su research group; Yurui Li of the Roland research group; Alexandra Zagalskaya, Marcos Felipe, and Tuan Anh Pham of the Lawrence Livermore National Laboratory; Jim Browning of Oak Ridge National Laboratory; and Robert Hillman of the University of Leicester.

The study, ‘controlling solvation in conducting redox polymers for selective electrochemical separation of nitrate from wastewater’ is available online. DOI: 10.1038/s41467-025-64895-w

Illinois Grainger Engineering Affiliations

Roland Cusick is an Illinois Grainger Engineering associate professor of civil and environmental engineering in the Department of Civil and Environmental Engineering.

Xiao Su is an Illinois Grainger Engineering associate professor of chemical and biomolecular engineering in the Department of Chemical and Biomolecular Engineering. He is also affiliated with the Beckman Institute for Advanced Science and Technology. He holds the Helen Corley Petit Scholar appointment.