The buildup of carbon dioxide, a major greenhouse gas, is increasingly impacting oceans around the world, making waters more acidic and threatening sea life.
Nanoengineers at the University of California, San Diego have made a splash in trying to overcome this obstacle. They've developed tiny motors smaller than the width of a human hair that can autonomously travel through oceans to remove CO2 and convert it to a usable solid form.
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In a proof-of-concept study, the team revealed that in just five minutes, the micromotors removed up to 90 percent of the carbon dioxide from a solution of deionized water. In a seawater solution, the micromotors removed 88 percent of the carbon dioxide in the same timespan.
"In the future, we could potentially use these micromotors as part of a water treatment system, like a water decarbonation plant," said Kevin Kaufmann, an undergraduate researcher and a co-author of the study.
The motors are six-micrometer-long tubes with an outer polymer surface that holds a chemical - enzyme carbonic anhydrase - designed to speed up the reaction between carbon dioxide and water and form bicarbonate.
Adding calcium chloride then converts the bicarbonate to calcium carbonate, a solid material commonly found in nature.
When a small amount of hydrogen peroxide is added to the solution, the conversion happens even faster, generating oxygen bubbles that propel the motors through the water. However, scientists are currently exploring ways to cut back on the two to four percent of hydrogen peroxide used as they focus on alternatives to use water itself to fuel the motors.
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Once the moters complete their mission, they can be recovered from the water and reused for future applications.
"If the micromotors can use the environment as fuel, they will be more scalable, environmentally friendly and less expensive," Kevin Kaufmann, an undergraduate researcher and co-author of the study, said in a press release, adding that in the future, these micromotors could likely be used as part of a water treatment system, like a water decarbonation plant.
via University of California, San Diego