Susan Rempe, a bioengineer, and Tuan Ho, a chemical engineer, both of Sandia National Laboratories, examine an artistic rendering of the chemical composition of a particular type of clay. Their group is looking at the possibility of using clay to absorb carbon dioxide. Credit: Image courtesy of Sandia National Laboratories and Craig Fritz
Researchers at Sandia National Laboratories are looking at clay as a direct air carbon dioxide absorber.
Although practically doubling during the Industrial Revolution, carbon dioxide only makes up 0.0415% of the air we breathe. Carbon dioxide is a gas that traps heat very effectively and contributes to climate change.
This poses a problem for scientists who are trying to develop artificial trees or other strategies for removing carbon dioxide from the atmosphere directly. A scientific team lead by Sandia National Laboratories is working to find a solution to that problem.
The team, led by Sandia chemical engineer Tuan Ho, has been researching how a certain type of clay may absorb and store carbon dioxide using sophisticated computer simulations and laboratory tests.
The researchers submitted a report in The Journal of Physical Chemistry Letters on February 9 in which they discussed their preliminary findings.
According to Ho, the paper’s principal author, “These fundamental findings offer potential for direct-air capture; that is what we’re aiming towards.” “Clay is incredibly cheap and widespread in nature. If this high-risk, high-reward initiative does result in a technology, it should enable us to drastically lower the cost of direct-air carbon collection.
Why do we trap carbon?
In order to lessen the effects of climate change, such as more frequent and severe storms, rising sea levels, and a rise in droughts and wildfires, excess carbon dioxide from the Earth’s atmosphere is captured and stored underground. This carbon dioxide might be extracted directly from the air, which is more technically difficult, or from fossil fuel-burning power stations, other industrial facilities, such cement kilns. One of the least contentious methods being examined for addressing climate change is carbon capture and sequestration.
Susan Rempe, a Sandia bioengineer and senior scientist on the project, said, “We would want affordable energy without destroying the ecosystem.” “We can reduce the amount of carbon dioxide we produce by how we live, but we have no control over what our neighbours do. In order to lower air pollution and lessen our neighbours’ emissions of carbon dioxide, direct-air carbon capture is crucial.
Ho suggests that carbon dioxide may be captured using clay-based devices similar to sponges, and then the captured carbon dioxide could be “squeezed” out of the sponge and injected underground. Perhaps the clay may be utilised more as a filter to sequester carbon dioxide from the air.
Clay is not only affordable and abundantly available, but it also has a high surface area, is stable, and is made up of numerous microscopic particles with fissures and crevasses that are roughly a hundred thousand times smaller than the diameter of a human hair. According to Rempe, these minuscule spaces are known as nanopores, and they are capable of changing their chemical properties.
Rempe has previously researched carbon dioxide collecting nanostructured materials. She was actually a member of the group that investigated a biological catalyst for converting carbon dioxide into water-stable bicarbonate, designed a thin, nanostructured membrane to shield the biological catalyst, and won a patent for their bio-inspired, carbon-catching membrane. Naturally, this membrane is not created from cheap clay and was first intended to be used in industrial settings or fossil fuel-burning power plants, according to Rempe.
She explained that there are two complementary potential solutions to the same issue.
How can the nanoscale be simulated?
A type of computer simulation called molecular dynamics examines the motions and interactions of atoms and molecules at the nanoscale. Scientists can determine a molecule’s stability in a specific environment, such water-filled clay nanopores, by observing these interactions.
Ho asserted that “molecular simulation” is a potent tool for researching interactions at the molecular level. The purpose of using this knowledge to develop a clay material for carbon-capture applications is to completely understand what is happening between carbon dioxide, water, and clay.
According to Ho’s molecular dynamics simulations, carbon dioxide can be significantly more stable in wet clay nanopores than in plain water in this situation.
This is due to the fact that water atoms do not equally distribute their electrons, leaving one end slightly positively and the other slightly negatively charged. Nonetheless, Rempe noted that carbon dioxide atoms do share electrons equally and that the gas is more stable around similar molecules, such as the silicon-oxygen regions of clay, much like oil is around water.
Ho added that researchers from Purdue University under the direction of Professor Cliff Johnston recently conducted tests to demonstrate that water contained in clay nanopores absorbs carbon dioxide at a rate greater than that of free water.
Ho said that Sandia postdoctoral researcher Nabankur Dasgupta discovered that carbon dioxide is converted into carbonic acid more favourably and with less energy inside the oil-like sections of nanopores than it does in plain water. The oil-like sections of clay nanopores, he continued, ultimately make it possible to capture more carbon dioxide and store it more easily by improving this conversion and requiring less energy.
According to what has been discovered thus far, clay is an effective substance for trapping carbon dioxide and transforming it into another molecule, according to Rempe. “And we know why this occurs, so the synthesis experts and engineers may change the substance to improve the oil-like surface chemistry. The simulations can also serve as a guide for trials that test novel ideas on how to encourage the transformation of carbon dioxide into other beneficial chemicals.
In order to figure out how to extract carbon dioxide back out of the nanopore, Ho stated that the project’s further steps will involve molecular dynamics simulations and experiments. They intend to conceive a clay-based direct-air carbon capture system before the project’s end, which will take three years.
The Journal of Physical Chemistry Letters, 9 February 2023, “Hydrophobic Nanoconfinement Enhances CO2 Conversion to H2CO3,” Nabankur Dasgupta, Tuan A. Ho, Susan B. Rempe, and Yifeng Wang.
Accessed at: 10.1021/acs.jpclett.3c00124
The Laboratory Directed Research and Development programme at Sandia provides funding for the project. The Center for Integrated Nanotechnologies, an Office of Science user facility run by Sandia and Los Alamos national laboratories for the Department of Energy, served as a location for some of the research.
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