Scientists Turned Dairy and Tofu Waste Into Beads That Pull CO2 From the Air
Every time a factory produces yogurt, cheese, or tofu, it also produces huge amounts of protein-rich liquid that mostly gets poured down the drain. For years, that waste has been little more than a disposal problem. Now, a team of scientists in Switzerland has figured out how to transform it into one of the most promising tools in the fight against climate change — a tiny bead that pulls carbon dioxide directly out of the air.
Carbon dioxide, or CO2, is a greenhouse gas — a gas that traps heat in Earth's atmosphere, much like how the glass walls of a greenhouse keep plants warm even in winter. Human activity has pumped so much CO2 into the air over the past two centuries that temperatures around the world are rising, which affects weather patterns, sea levels, and ecosystems everywhere. Scientists agree that cutting new emissions is essential, but many also say we need to actively remove CO2 that is already in the atmosphere. That is where a process called direct air capture, or DAC, comes in. DAC technologies work by pulling CO2 directly from surrounding air and storing it so it cannot continue warming the planet.
The problem with most current DAC systems is that they are extremely expensive and require massive amounts of energy to operate, often generated by burning more fossil fuels. That creates something of a contradiction — fighting pollution by creating more of it. Researchers at ETH Zurich, a leading science and technology university in Switzerland, have developed a new approach designed to sidestep those problems entirely.
The team, led by materials scientist Raffaele Mezzenga, extracted proteins from the waste liquid produced during dairy and tofu manufacturing. They assembled these proteins into incredibly thin, thread-like structures called amyloid fibrils — fibrils being tiny fibres at a microscopic scale. These fibrils were then combined with a chemical called potassium hydroxide and pressed into small porous beads roughly the size of a pea. Porous means full of tiny holes, which gives the beads an enormous surface area for trapping gas, similar to how a sponge has millions of tiny pockets that hold water. When air passes over the beads, the potassium hydroxide reacts chemically with CO2 and locks it inside as a stable salt compound called hydrogen carbonate.
The results from lab testing were impressive. Just one gram of the bead material captured 97 milligrams of CO2 from ordinary air — outperforming conventional DAC materials by anywhere from 10 to 50 percent. Even more importantly, releasing the captured CO2 does not require high temperatures or large amounts of electricity. Instead, researchers simply spray the beads alternately with a mild acid and a mild base for about ten minutes at room temperature, which breaks the chemical bonds holding the CO2 and releases it cleanly. The acid, base, and beads can all be reused afterward. In testing, the beads maintained their performance over 30 full cycles without any meaningful loss of efficiency, and researchers believe they could eventually handle thousands of cycles before needing replacement.
When the beads eventually do wear out, they do not just become trash. Because the material is entirely organic and food-grade — meaning it meets the safety standards used for actual food products — the spent beads could be applied to farm soil as fertilizer or converted into biofuel. This fits into what scientists call a circular economy, a system where materials keep being reused or transformed rather than thrown away. The team also ran a life cycle analysis, which is a method of measuring a product's total environmental impact from creation to disposal, and found that their approach causes significantly less environmental harm than existing DAC technologies across its entire lifespan.
The research, published in the prestigious journal Proceedings of the National Academy of Sciences, is still at an early stage. So far, scientists have only tested a few grams of material in a controlled lab setting. Scaling the technology up to capture meaningful amounts of CO2 on a global level will require much more research and engineering work. However, Mezzenga is optimistic. He has spent nearly two decades working with amyloid fibrils and has previously used them to develop biodegradable plastic alternatives and water purification systems. He believes the spray-based release system used in this process is already compatible with existing industrial equipment, which could speed up adoption. While the exact cost per tonne of CO2 removed has not yet been calculated, the team expects it to be significantly lower than current DAC methods.
The idea that the byproduct of making your favourite snack could one day help stabilize Earth's climate is a reminder that solutions to big problems can sometimes come from unexpected places — including what we once considered rubbish.
Source: SciTechDaily