Cutting CO2 Emissions and Purification of H2O Possible Through Plastic That Mimics Leaf Pores

by Medindia Content Team on Oct 13 2007 7:17 PM

A new membrane that mimics pores found in plants and allows carbon dioxide to move through while preventing the movement of methane, could be used to cut greenhouse gas emissions while purifying water at the same time.

The membrane allows small molecules such as those of carbon dioxide to move through its pores while preventing the movement of larger molecules such as methane.

Separating carbon dioxide from methane is important in natural gas processing and gas recovery from landfill.

Dr Anita Hill of CSIRO Materials Science and Engineering, part of the research team, said: “This plastic will help solve problems of small molecule separation, whether related to clean coal technology, separating greenhouse gases, increasing the energy efficiency of water purification, or producing and delivering energy from hydrogen”.

“The ability of the new plastic to separate small molecules surpasses the limits of any conventional plastics. It can separate carbon dioxide from natural gas a few hundred times faster than current plastic membranes and its performance is four times better in terms of purity of the separated gas,” she said.

She said the secret lay in the hourglass shape of the pores, which helped separate molecules faster and using less energy than other pore shapes.

In plant cell membranes, hourglass-shaped pores known as aquaporins selectively conduct water molecules in and out of cells while preventing the passage of other molecules such as salt. Dr Hill said the research had shown how plastics could be systematically adjusted to block or pass different molecules depending on the specific application.

For example, these membranes might provide a low energy method for the removal of salt from water, carbon dioxide from natural gas, or hydrogen from nitrogen, she said. Each of these small molecule separations has impact on Australia’s interrelated issues of water scarcity, clean energy, and climate change mitigation. The new plastic is durable and can withstand high temperature, which is needed for many carbon capture applications. Heat-stable plastics usually have very low gas transport rates, but this plastic surprised us by its heightened ability to transport gases,” Dr Hill said.

The international research team included scientists from the Hanyang University in Korea, the University of Texas, the US and CSIRO, Australia.