Surgical sorbents capture CO2

Technology currently used to prevent infection in medical implants and to prepare microcapsules for drug delivery may also one day help ease concerns about global warming.

To investigate this possibility, a collaboration has been formed linking a medical school, a university department of chemical engineering, and the US DOE Office of Fossil Energy's National Energy Technology Laboratory (NETL). The collaboration was made possible through NETL's University Research Initiative.

Under the University Research Initiative, NETL scientists are working with the West Virginia University School of Medicine and the University of Pittsburgh's Chemical Engineering Department on a nanotechnology called ‘electrostatic layer-by-layer self-assembly,’ or LBL. Originally developed for medical applications, the technology shows promise in the development of sorbent technology for the capture of carbon dioxide.

NETL has expertise in developing sorbents - materials that can remove various chemicals from the gases produced by fossil fuel combustion. Some of the sorbents use amines, chemical compounds that contain nitrogen as the key atom, to remove carbon dioxide.

To prepare for CO2 capture, amine sorbents are deposited within a substrate structure - a structure similar to a sponge - in layers. Using nanotechnology, the deposits can be made very uniform, and the more uniform the deposition, the more effective the sorbent is at CO2 removal.

The LBL process involves repeatedly dipping a substrate into an amine solution, each dip creating a layer of approximately 1-2 nanometres. The process has the potential to produce highly efficient, highly uniform solid sorbents containing perhaps 100 times more of the amines than are deposited by the sorbent-preparation technologies commonly used today.

McMahan Gray, an NETL scientist collaborating on the project said: ‘We're excited about taking medical technology used in biological systems and using it in different industrial systems for carbon dioxide capture.

‘For the universities, this is a branching out - an alternative use for the nanotechnology they're doing now. This new application has challenges for them. They work at scales of less than a micrometer, and we're working at 100 microns and up. We have to see how much coverage of the substrate we can get, and how deep into the pores the material will go.

‘In the immobilisation process we've been using at NETL, because of the random distribution of the chemicals on the porous structure, deposition might not be uniform. We hope with this we will use less chemical and get more uniform deposition.’

The project is scheduled for a year, with potential extensions for up to two more years.