Scientists from the University of Toronto and Imperial College London have developed a new sponge that they believe could help clean up water that has been contaminated by offshore drilling. The scientists say that drilling and fracking for oil under the seabed produces 100 billion barrels of oil-contaminated wastewater each year due to tiny oil droplets released into the surrounding water.
The new sponge that the team has developed could remove up to 90% of oil microdroplets from wastewater within ten minutes. The team says that when the sponge is used, the oil coats its surfaces like a thin film via a process called adsorption. After use, the sponge can be treated with a solvent to release the oil from the sponge. The oil can be recycled, and the sponge can be used again.
The new sponge is a second-generation device that is slightly less efficient than the first iteration of the sponge. The first sponge could remove 95% of the oil but needed three hours to do so. The new sponge removes only 90% of the contamination, but its ten-minute time frame is useful in industry. The new sponge also works over a much wider pH range than the previous version.
Scientists used polyurethane foams in the original sponge to separate tiny droplets of oil from wastewater. The pore size was tweaked and the surface area to design a sponge that attracts and captures oil droplets while letting water flow through. Improving that design from the second-gen sponge involved adding tiny nanocrystalline silicon.
Those particles allowed the sponge to capture and retain oil droplets as a coating on the pores’ surfaces, a process called critical surface energy. The critical surface energy was manipulated to get the droplets of oil to catch on tightly. In the future, the team hopes to use the sponges to perform other tasks like removing bacteria from saltwater and treating other types of contamination.