Tiny Submarines Gather Oil

To remove oil and other organic contaminants from water, scientists may someday deploy submarines—microsubmarines. Tubular microscale engines zip through solution by converting hydrogen peroxide fuel into oxygen bubbles that they then expel for propulsion. By giving these tiny swimmers a hydrophobic monolayer coating of long-chain alkanethiols, researchers have transformed them into oil-gathering microsubmarines that are capable of capturing, transporting, and separating oil contamination from water (ACS Nano, DOI: 10.1021/nn301175b). Joseph Wang of the University of California, San Diego, and coworkers created the tiny subs, each about 8 μm long, by using a membrane-template electrodeposition process. The tubes are made of a platinum core, which oxidizes hydrogen peroxide into oxygen bubbles. This core is surrounded by a layer of poly(3,4-ethylenedioxythiophene) or PEDOT, then a layer of nickel, and finally a layer of gold. Wang’s group then coated the gold surface with a monolayer of dodecanethiol. When placed in water contaminated with oil, the microsubmarines picked up as much as 10 times their volume in oil droplets as they zoomed along. “Such high oil-adsorption ability indicates considerable promise for the cleanup of contaminated water samples,” note the researchers.