Liquid metal can capture CO2 and recycle it at low cost
A global collaboration has demonstrated how liquid gallium can be used to help achieve the important goal of zero net carbon emissions.
Engineers at UNSW (University of New South Wales) have led research into a new, inexpensive way to capture and convert greenhouse CO2 emissions using liquid metal.
The process can be carried out at room temperature and uses liquid gallium to convert carbon dioxide into oxygen and a high-value solid carbon product that can then be used in batteries, or in aircraft construction or manufacturing.
The findings have been published in the journal Advanced Materials and the team led by Professor of Chemical Engineering Kourosh Kalantar-Zadeh says the new technology has the potential to be used in a wide variety of ways to significantly reduce levels of greenhouse gases in the atmosphere.
"We see very robust industrial applications with respect to decarbonization. This technology offers an unprecedented process to capture and convert CO2 at an exceptionally competitive cost," Junma Tang, the paper's first author, said in a statement.
"Applications could be in automobiles to convert polluting exhaust gases, or even on a much larger scale at industrial sites where CO2 emissions could be captured and processed immediately using this technology.
"We have already scaled this system to two-and-a-half liter dimensions, which can handle about 0.1 liter of CO2 per minute. And we have tested it running continuously for a whole month and the efficiency of the system does not degrade."
The newly discovered process dissolves captured CO2 gas in a solvent around gallium nanoparticles, which exist in a liquid state above 30 degrees Celsius.
The reactor also contains nanometer-sized solid silver rods that are the key to generating the triboelectrochemical reactions that take place once mechanical energy (e.g., stirring/mixing) is introduced.
A triboelectrochemical reaction occurs at the solid-liquid interfaces due to friction between the two surfaces, and an electric field is also created that triggers a chemical reaction.
The reactions break the carbon dioxide into gaseous oxygen, as well as carbonaceous sheets that 'float' to the surface of the vessel due to density differences and can therefore be easily extracted.
In their paper, the research team shows a 92 percent efficiency in converting one ton of CO2 as described, using only 230kWh of energy. They estimate that this equates to a cost of around $100 per ton of CO2.
