There’s gold in oilfield wastewater … or lithium, that is. Argonne National Laboratory researchers are advancing a separation process that could make it profitable to extract lithium and other critical elements out of the water generated by oil and gas operations, geothermal plants and battery recyclers.

Yuepeng Zhang, an Argonne principal materials scientist who is leading the research, wrote about the project in a July 2, 2024, Chemical Processing article called, “Extracting Critical Materials From Gas and Oilfield Wastewaters.”

Since then, the scientists have expanded their target elements to include cobalt, copper, nickel and semiconductor materials like gallium and germanium. These are elements on the Department of Energy’s list of critical minerals and materials considered essential for energy technologies.

The researchers also have shifted from absorption materials to direct extraction, which requires less energy and makes the process more efficient and cost-effective, Zhang said.

The previous process relied on absorption materials with cavities that would bind with certain elements, enabling preferential complexing. That method works, but releasing the captured ions afterward requires considerable energy. Argonne's team is developing other selective layers focused on 2D materials, which either allow the desired element to pass through the membrane for collection or allow non-selective elements to pass through, leaving the target ion behind, Zhang said.

The research team is also developing its own ion-exchange membrane that does not use per- and polyfluoroalkyl substances, or PFAS, by eliminating the use of fluorine during the synthesis process or in the membrane itself, according to Zhang.

“Before, we relied on commercial [membranes] such as Nafion, which is expensive and also has the potential risk or environmental concerns of PFAS materials,” said Zhang.

The enhanced selectivity process is a major milestone toward commercial viability. Fewer passes require less energy, result in higher throughput and are more environmentally friendly. These factors also make the process potentially more profitable than absorption technologies, Zhang said. 

Argonne is in discussions with commercial partners to bring the technology to market. The lab has not entered into a formal agreement with any collaborators but has submitted two proposals that are pending, Zhang said.

If federal funding or direct industry funding comes through, it will take another two to three years to move through all the validation steps before going to market. The process involves a large-scale validation with real feedstock and then a market comparison against the incumbent technology.

The target industries for the technology include battery materials, oil and gas and semiconductor sectors. Rare-earth separation from sources such as recycled drivetrains and ore concentrates is another potential market, though a longer-term one. That’s because the technologies needed to efficiently separate rare-earth elements that sit adjacent to each other on the periodic table don't yet exist, Zhang said.

The long-term goal of the Argonne-led project is to create a platform technology that uses selective layers to separate various elements from impurities and a water testbed to assess platform’s capabilities under various feedstocks. High-concentration impurities require additional pretreatment to eliminate issues like scaling on the membrane.

“That means there are multiple steps in terms of the entire separation process,” Zhang said. “The optimization of these processes as a whole is important because that determines the overall process efficiency and how we synchronize the throughput at different steps.”

The scientists acknowledged that real-world deployment won't be a single step. Pretreatment will be needed to strip high-concentration impurities that could cause scaling/precipitation on the membrane, even if they aren't the target ion.

Organizations interested in learning more about how they might partner with Argonne in this space can do so at www.anl.gov/partners.