A new frontier in water purification

Removal and recovery of ammonia from simulated wastewater using Ti3C2Tx MXene in flow electrode capacitive deionization for water purification

One in three people worldwide lacks access to clean drinking water and basic sanitation services. These problems have only increased across the world due to the effects of climate change. Developing countries and vulnerable communities are the most affected by the adverse effects of water scarcity and a lack of access to water purification facilities.

“Water scarcity is one of the biggest challenges of the 21st century,” David Estrada, associate professor of materials science and engineering, said. “At our lab, we are committed to finding solutions for problems without regard for political, socioeconomic, or cultural boundaries. This new system can be tailored to fit the water remediation needs of communities of different sizes and economic backgrounds across the globe.”

Boise State researchers from the College of Engineering joined with researchers from Drexel University and the Idaho National Laboratory to investigate a simple, energy-efficient technique to remove ammonia from agricultural wastewater. Research is co-led by Estrada and Tedd Lister, from the Idaho National Laboratory. The group’s work was published in the Nature Partner Journal, Clean Water.

The research team utilised capacitive deionisation, an emerging water treatment technique in which water flows between two oppositely charged electrodes. This technique polarises ionic impurities in wastewater, causing the ions to be attracted and stored in the opposing electrodes. It provides a new opportunity in water purification

“It takes about 20 times as much energy to synthesise ammonia from fossil fuels compared to our approach,” Lister said. “This generates up to four times the amount of carbon dioxide as the amount of ammonia that is synthesised. It highlights the importance of recycling our resources using such energy-intensive techniques.”

Research findings around water purification studies

The team examined previous studies which explored carbon-based materials as electrodes. These materials were limited in chemical diversity, surface chemistries, and surface-area-to-volume ratio. That limits the performance of the capacitive deionisation technique. The team partnered with Chris Schuck and Yury Gogotsi at Drexel University to investigate a new approach utilising MXenes. That is an inorganic compound composed of layers of nitrides, carbonitrides, or metal carbides.

“MXenes have a unique combination of properties that make them very attractive for electrochemical applications,” said Naqsh Mansoor, a Boise State graduate student in the Micron School of Materials Science and Engineering and the first author of the paper. “The fanned-out structure of MXenes allows plenty of intercalation space so that removed pollutant ions can absorb on the surface and insert themselves between the layers.”

The team’s research found a 100 times improvement in the deionisation capacity when using MXenes compared to activated carbon-based electrode systems. This resulted in more pollutant ions being pulled from the wastewater stream while using less of the electrode material. As a result, their water purification technology was significantly improved.

The Fulbright Fellowship Program and Idaho National Laboratory Directed Research and Development Program sponsored the team’s research.

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