Clay shows promise for carbon capture

Led by Purdue University in collaboration with Sandia National Laboratories, the study explored a group of clays called smectites which have large internal surface areas. Focusing on a particular smectite known as saponite, they examined how it handles carbon dioxide and water vapour as they compete for space in the clay's tiny internal pores. The work is published in The Journal of Physical Chemistry C.

"Clay minerals have an exceptionally high surface area," said research lead Cliff Johnston, Professor of Agronomy at Purdue. 

"One tablespoon of clay has approximately the same surface area as an American football field. Most of this surface area is found in the internal pores of the clay. Over decades of research, we have found that these internal pores have polar and nonpolar regions. Molecules like CO2 prefer the nonpolar regions, whereas water vapour prefers the polar regions. By selecting certain types of clay and manipulating their ionic structure, we can optimise for materials that can uptake CO2."