Foam absorbs carbon dioxide

Materials World magazine
4 Oct 2017

Researchers at Rice University, USA, have created a reusable carbon dioxide absorbing foam, which can be used in air filters and for general gas absorption.

It is made from two-dimensional sheets of hexagonal-boron–nitride (h-BN), and polyvinyl alcohol (PVA), which serves as a glue when mixed into a solution with flakes of h-BN when freeze-dried. ‘It binds the junctions as the microscopic sheets arrange themselves into a lattice,’ the researchers state in their study, Lightweight Hexagonal Boron Nitride Foam for CO2 Absorption, published in ACS Nano.

The alcohol helped to make the foam more robust, as by itself, it is highly porous.

The researchers were surprised by the efficiency of PVA. ‘Even a very small amount of PVA works. It helps make the foam stiff by gluing the interconnections but it doesn’t change the surface area,’ said co-author Chandra Sekhar Tiwary. 

The researchers say that in molecular dynamics simulations, the foam absorbed 340% of its own weight in carbon dioxide. After use, the greenhouse gas can be evaporated out of the foam, making it reusable. 

Looking ahead, the team wants to gain control over the foam’s pores so that they can tailor applications for it. In future, it might be used to separate oil from water, and, if coated with another polymer (polydimethylsiloxane), the foam can shield lasers, which can be used for biomedical applications. 

It is not the first time that artificial foam is being created to soak up carbon dioxide. In 2010, researchers from the University of Cincinnati, USA, caused furore because their photosynthetic foam was able to lock captured carbon dioxide away as glucose using enzymes, with the ultimate goal to extract it and turn it into biofuel, something the researchers struggled to figure out, and to consider for further research.