Scientists use ordinary stones to capture carbon dioxide in the air permanently and cheaply

To find a solution to the environmental crisis derived from excess carbon dioxide emissions, it is said that the scientific community has searched under the stones. It is a metaphor, of course, to talk about the numerous studies, proposals or inventions that have been carried out to avoid the worst effects of climate change. But you imagine that the solution is literally on the stones?

That is the proposal of a group of researchers from Stanford University, in the United States, who developed a technique that captures carbon dioxide with ordinary rocks, and does so permanently and a low cost. The key is in the minerals found in the rocks.

The idea is not new. Scientists have been investigating how to capture and contain carbon dioxide in the rocks (Like the basalta volcanic rock). And is based on the fact that some rocks can absorb CO2 naturally. This process is called weathering, but the problem is that it takes hundreds or thousands of years. Climate change challenges are a bit more urgent.

“The Earth has an inexhaustible supply of minerals capable of eliminating CO2 from the atmosphere, but these do not react for themselves with rapidity to counteract human emissions of greenhouse gases,” says a statement in relation to the study published in Nature.

However, chemicals Matthew Kanan and Yuxuan Chen have found a way to accelerate this natural process by conversioning a group of minerals known as silicates, in these fast weathering vehicles. “Our work solves this problem in a way that we believe is exceptionally scalable,” they said.

“We imagine a new chemistry to activate inert silicate minerals through a simple ion exchange reaction,” Chen explained. The inspiration to get to your idea: the elaboration of cement.

The secret: change one thing for another

To make cement, an oven to 1,400 degrees converts the limestone into calcium oxide, a reactive chemical compound, which is then mixed with sand. The researchers replaced the sand with a mineral called magnesium silicate. When heated, the two minerals, magnesium silicate and calcium oxide, exchange ions and this transformation results in magnesium oxide and calcium silicate, two minerals that quickly get used.

“The process acts as a multiplier,” Kanan said. “A reactive mineral, calcium oxide, and a magnesium silicate that is more or less inert, and two reactive minerals are generated.”

At the time of checking their results, the researchers presented calcium silicate and water magnesium oxide and pure carbon dioxide. In two hours, both materials were completely transformed into new carbonate minerals with CO2 carbon trapped inside. They also did the test when exposing the minerals in the air, instead of pure CO2. In this case, weathering took a few weeks to a few months, but still, it was much faster than the natural weathering process that takes centuries.