Purdue University researchers have developed a process to capture CO₂ at its source using a liquid filter, rather than letting it be emitted into the atmosphere. (Adobe Stock Photo/Dzmitry Halavach)

“2023 was the hottest year on record, and it’s all because of greenhouse gases like carbon dioxide,” said Antonio Esquivel-Puentes, a Ph.D. candidate in agricultural and biological engineering. “The cement industry alone generates 8% of all global CO₂ emissions. Factories just cannot continue to emit large amounts of carbon dioxide into the atmosphere.”

“Researchers around the world are working on technologies to capture CO₂ from the atmosphere,” said Mirian Velay-Lizancos, assistant professor of civil engineering. “But why not capture it at its source — at the factories where it would otherwise be ejected into the atmosphere?”

Velay-Lizancos theorized using a liquid filter, saturated with hydroxides from industrial by-products, could be used to capture the CO₂ in an efficient way at large scale. Working with Esquivel-Puentes and Luciano Castillo, Kenninger Professor of Renewable Energy and Power Systems, the team decided to build a tabletop prototype to test their theory.

Air polluted with CO₂ is injected into a reservoir that contains reactive aqueous solution, where it reacts with the insoluble hydroxides, forming carbonates. Once the new compound is formed trapping the carbon, it precipitates to the bottom of the reservoir, where it can be separated from the water. The resulting filtered air can be safely released, and the filtered water can be reused in the process.

In this small-scale experiment, CO₂ (left) is pumped into a liquid filter (top). The CO₂ reacts with the solution and forms carbonates, which settle at the bottom of the tank and can be removed. The liquid solution can then be recycled and reused again. (Photo courtesy Antonio Esquivel-Puentes)

“Some carbonates, such as calcium carbonate, are actually a very useful by-product,” said Esquivel-Puentes. “Cement plants use it as raw material at the beginning of their manufacturing process. So, this process could provide a double benefit: reducing their CO₂ emissions, and reducing their need to mine for new calcium carbonate by reusing this by-product.”

The cement industry is a $406 billion global industry that emits 1.6 billion metric tons of CO₂ a year. Esquivel-Puentes estimates that by reducing that number, even by just 50%, would impact the lives and health of more than 176 million people around the world.

The team are analyzing methods of scaling up their process for potential use in factories, power plants, diesel generators, ships and large vehicles, and any other process that burns fossil fuels. They are also experimenting with modifying the composition of the solution and using ultraviolet radiation in the liquid filtering process to remove nitrogen oxides, another suite of dangerous greenhouse gases.

“Climate change is an issue we should all be addressing on multiple fronts,” said Velay-Lizancos. “This Purdue technology has already received significant interest from industry partners. It can provide a double benefit of reducing CO₂ and generating a valuable by-product. It’s our hope that this technology will lead to a more sustainable future for all of us.”

The researchers have disclosed the innovation to the Purdue Innovates Office of Technology Commercialization, which has applied for a utility patent through the U.S. Patent and Trademark Office to protect the intellectual property. Industry partners interested in developing or commercializing the work should contact Parag Vasekar, business development and licensing manager - physical sciences, at psvasekar@prf.org.

Writer: Jared Pike, jaredpike@purdue.edu, 765-496-0374

Source: Mirian Velay-Lizancos, mvelayli@purdue.edu

Luciano Castillo, lcastillo@purdue.edu