Researchers at ETH Zurich have developed a sustainable and cost-effective method for direct air capture by repurposing liquid protein waste from tofu and dairy production. By transforming these leftovers into porous, sponge-like beads infused with potassium hydroxide, the team created a material capable of absorbing CO2 from ambient air and converting it into baking soda. This innovative approach outperforms existing capture technologies by 10 to 50 percent, offering a more efficient and environmentally friendly solution to reducing atmospheric CO2 emissions while utilizing materials that are non-toxic, stable, and fully biodegradable.
The process begins by shaping discarded protein into long threads, which are then treated with potassium hydroxide to create small, absorbent beads. According to lead author Zhou Dong, these beads successfully extracted 97 milligrams of CO2 per gram of material during laboratory testing. Unlike conventional filters that demand significant energy for high-heat and high-pressure operations, this new material functions at room temperature. To release the captured gas for storage, the beads are simply sprayed with a mild acid and base for ten minutes, a process that requires far less power than traditional methods.
Durability is another significant advantage of this protein-based technology. While many synthetic alternatives degrade rapidly, these beads remained stable and efficient through 30 test cycles. Furthermore, the material is entirely organic and food-grade, meaning it does not contribute to landfill waste once it reaches the end of its lifespan. Instead, the spent beads can be repurposed as biofuel or fertilizer. While the research team, led by Raffaele Mezzenga, acknowledges that large-scale testing is still required to confirm these results outside of the laboratory, they remain optimistic that the technology is highly scalable for future carbon-capturing applications.