ripple effect

UH team develops method to use electricity to remove harmful carbon from ocean waters

UH assistant professor Mim Rahimi published a paper on the development of his lab's emerging negative emissions technology known as electrochemical direct ocean capture. Photo via UH.edu

Researchers at the University of Houston are developing a new, cost-effective way to help rid oceans of harmful carbon dioxide and fight the effects of climate change.

UH assistant professor Mim Rahimi published a paper on the development of his lab's emerging negative emissions technology known as electrochemical direct ocean capture (eDOC) in the journal Energy & Environmental Science this month.

The paper details how Rahimi's team is working to create electrochemical tubes to remove dissolved inorganic carbon from synthetic seawater, according to a release from UH. The process aims to amplify the ocean’s ability to absorb carbon and can easily be integrated into existing on-shore and off-shore infrastructure, including desalination plants and oil rigs.

Unlike other methods that involve complex processes, expensive materials and specialized membranes, the eDOC method focuses on adjusting the ocean water's acidity using affordable electrodes.

“While eDOC won’t single-handedly turn the tide on climate change, it enriches our mitigation toolkit,” Rahimi said in a statement. “In this global challenge, every innovative approach becomes invaluable.”

Rahimi's research is funded by a $250,000 grant from the U.S. Department of Energy and preliminary research was sponsored by UH Energy’s Center for Carbon Management in Energy.

“The promise of eDOC is undeniable, but scaling it, optimizing costs and achieving peak efficiency remain challenges we’re actively addressing,” he added in a statement.

Late last month, UH shared details on another carbon removal project it is involved with–this time focused on direct air capture (DAC). Known as the Pelican Gulf Coast Carbon Removal study–led by Louisiana State University and including UH and Shell—the project looks at the feasibility of a DAC hub that would pull carbon dioxide from the air and either store it in deep geological formations or use it to manufacture various products, such as concrete.

In August, UH announced that the project received nearly $4.9 million in grants, including almost $3 million from the U.S. Department of Energy. Click here to read more.

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A View From HETI

Simon M. King, a Rice University sophomore, served as the first author on a recent study of a new process for recycling lithium-ion batteries. Photo courtesy Rice

Rice University researchers have uncovered a more energy-efficient and faster way to recycle critical minerals from used lithium-ion batteries.

Traditional methods rely on high heat, long processing times and harsh chemicals to recover a small fraction of critical materials from batteries used in everything from smartphones to electric vehicles. However, the team from Rice's Department of Materials Science and Nanoengineering developed a process that uses a water-based solution containing amino chlorides to extract more metals in less time

The team published the findings in a recent edition of the scientific journal Small.

Simon King, a sophomore studying chemical and biomolecular engineering who completed this work as a summer research fellow at the Rice Advanced Materials Institute, served as first author of the study. He worked with corresponding authors Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor of Engineering, and Sohini Bhattacharyya, a research scientist in Ajayan’s lab.

By using a hydroxylammonium chloride (HACI) solution, the team achieved roughly 65 percent extraction of key battery metals in just one minute at room temperature, according to the study. The efficiencies grew to roughly 75 percent for several metals under longer processing times.

“We were surprised by just how fast the reaction occurs, especially without the involvement of high temperatures,” King said in a news release. “Within the first minute, we’re already seeing the majority of the metal extraction take place.”

By not requiring high temperatures or long reaction times, Rice predicts the process could have a major impact on cost and the environmental impact of lithium battery recycling. Additionally, the water-based HACI solution makes waste handling easier and lowers certain environmental risks.

In addition to extracting the materials, the team went on to demonstrate that the recovered metals could be recycled and reprocessed into new battery materials.

“A big advantage of this system is that it works under relatively mild conditions,” Ajayan added in the release. “That opens the door to more sustainable and scalable recycling technologies.”

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