ADVANCED MATERIALS & PROCESSES | JULY/AUGUST 2025 14 SUSTAINABILITY POLYMER MEMBRANE SEPARATES LITHIUM Researchers at Imperial College London developed a technology to extract lithium from saltwater sources such as salt-lake brines or geothermal brine solutions as an alternative to mining. Conventional lithium extraction from brines takes months and uses significant amounts of water and chemicals, while the new method uses a membrane to separate lithium from salt water by filtering it through tiny pores. A typical problem with this approach is that the pores also let through magnesium and other contaminants, but the team developed a class of special polymers that are highly selective for lithium. This new generation of synthetic polymer membranes is based on materials known as polymers of intrinsic microporosity (PIMs), which contain tiny, hourglass-shaped micropores that provide ordered channels through which small molecules and ions can travel. In the latest study, researchers fine-tuned the micropores to become highly selective for lithium. Used in an electrodialysis device, the lithium ions are pulled through the membrane micropores by an electrical current, while larger magnesium ions are left behind. Tested on simulated salt-lake brines, the PIM membranes are highly selective for lithium and produce highpurity, battery-grade lithium carbonate. Regarding production, the polymers are soluble in common solvents and can be turned into membranes using established industrial techniques. Imperial has filed patent applications for the membranes and a range of different uses, including lithium extraction. www.imperial.ac.uk. CORAL REEFS INSPIRE GREEN BUILDING MATERIALS A research team at the University of Southern California is taking inspiration from coral reefs and their natural ability to create rigid structures by sequestering carbon dioxide. The new mineralpolymer composites demonstrate impressive mechanical strength, fracture toughness, and fireresistant properties. “Unlike traditional carbon capture technologies that focus on storing carbon dioxide or converting it into liquid substances, we found this new electrochemical manufacturing process converts the chemical compound into calcium carbonate minerals in 3D-printed polymer scaffolds,” explains Professor Qiming Wang. The method was directly inspired by how coral creates its aragonite skeletal structures, known as corallites. In nature, coral builds corallites through biomineralization, in which coral sequesters CO2 from the atmosphere during photosynthesis. It then combines the chemical compound with calcium ions from seawater to precipitate calcium minerals around organic templates. The team replicated this process by creating 3D-printed polymer scaffolds that mimic coral’s organic templates. Next, they coated them with a thin conductive layer. These coated structures were then connected to electrochemical circuits as cathodes and immersed in a calcium chloride solution. When CO2 was added to the solution, it underwent hydrolysis to be broken down into bicarbonate ions. These ions reacted with calcium in the solution to form calcium carbonate, which gradually filled the 3D-printed pores. This resulted in a dense mineralpolymer composite. After a rigorous life cycle assessment, researchers found that the manufactured structures have a negative carbon footprint. usc.edu. This salt brine at Lake Magadi, Kenya, could be a future site for lithium extraction. Courtesy of Wikimedia Commons. Researchers mimic the formation of coral reef structures as they develop new construction materials. Courtesy of Wikimedia Commons. Hydnum Steel is building a flat steel plant in Spain to become one of the leading clean steel producers in Europe. Hydnum will supply thyssenkrupp Materials Processing Europe with up to 100,000 tons of decarbonized flat steel per year for an initial seven-year period once the plant opens. hydnumsteel.com. BRIEF
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