As trees grow, they sequester about one metric ton of carbon dioxide for every cubic meter of wood. Now researchers have given wood this ability to absorb carbon dioxide, with the idea that furniture, homes and even entire buildings made of wood could continue the carbon-capture work of trees even after they have been cut down.
The idea, presented in the journal Cell Reports Physical Science, takes advantage of the porous structure of wood. Using a simple two-step process, the researchers fill these pores with tiny microparticles of a crystalline material that is known to be an excellent carbon dioxide sorbent.
Cement and steel are critical building materials of today’s world. But making them results contributes to about 14 percent of global carbon emissions. As construction increases in coming decades due to rising population, there is a growing call to increase the use of wood to make homes and buildings.
Modern construction uses engineered, high-tech wood called mass timber. A recent study shows that making new buildings out of mass timber could sequester a total of 20 gigatons of carbon over the next three decades because of the carbon dioxide taken up by the biomass as it grows.
Researchers from Rice University in Houston, TX and the University of Calgary in Canada found a way to boost this carbon-capture ability. Using natural wood as a template, they made a sustainable wood composite that can absorb carbon dioxide from air. The material is also stronger than regular wood.
The team starts with a piece of basswood. They boil it in a water-based chemical solution that removes lignin, the fibrous component of wood that imparts rigidity and strength. The inventors of this process have previously made wood that is foldable and lightweight like Styrofoam.
The lignin-stripped wood is bright white—because lignin also gives wood its dark color—and has long, hollow channels. Next, the researchers immersed it into a solution of crystalline microparticles of a material called metal-organic framework (MOF), which is porous and can form strong chemical bonds with carbon dioxide.
The MOF particles fill the hollow channels in the wood pieces, the researchers found via imaging. Tests showed that the particles also added mechanical strength to the wood composite.
Being diodegradable and potentially recyclable, the carbon-soaking wood composite should bring down the carbon footprint of conventional structural materials like cement and plastic. Advancing this material design concept to a practical technology, however, will first require more detailed studies, the researchers say, such as the effect of contaminants and moisture on performance and lifetime of the material. They also plan on enhancing the carbon dioxide uptake using other sorbents or more sorbent filling, and on making such composites on larger scale.
Source: Soumyabrata Roy et al. Functional wood for carbon dioxide capture. Cell Reports Physical Science, 2023.