A team of nanoengineers from the University of California, San Diego invented tube-shaped micromotors that can remove carbon molecules from water while they swim. The technology potentially could be used to remove CO2 from the water column and counteract the deleterious effects of ocean acidification and global warming.
Led by nanoengineering professor Joseph Wang, the team created tube-shaped micromotors that measure six-micrometer in length. The microtubes contain an enzyme, carbonic anhydrase, which catalyzes the reaction between water and carbon dioxide. During this process, the carbon dioxide is rapidly converted to calcium carbonate, a solid and environmentally benign material found in chalk, cement and eggshells.
In the study, the team placed the micromotors in a water solution saturated with carbon dioxide and added hydrogen peroxide as a power source. With as little as two percent hydrogen peroxide, the micromotors used their continuous motors to swim at speeds of up 100 micrometers per second. Within five minutes, the micromotors removed 90 percent of the carbon dioxide from a deionized solution and 88 percent from a salt water solution.
Right now, his team is focusing on the propulsion system of the micromotors, which currently relies on hydrogen peroxide as an energy source. The hydrogen peroxide adds another layer of complexity to the system and requires the use of expensive platinum materials in the construction of each micro motor tubule. Wang and his team also are looking to develop a second series of micromotors that use water in the environment as their source of fuel. “If the micromotors can use the environment as fuel, they will be more scalable, environmentally friendly and less expensive,” said UCSD undergraduate researcher Kevin Kaufmann.
Though still in the early stages of development, Wang envisions a future where these micromotors could be incorporated into ocean water decarbonation plants. These plants would process incoming carbon dioxide-containing water and release clean water as a way to combat the rising level of carbon dioxide in oceans worldwide.