Scientists at the University of Toronto and Imperial College London have developed a new sponge they believe could help clean up seawater contaminated by offshore drilling. Scientists say that by releasing tiny droplets of oil into the surrounding water, 100 billion barrels of oil-contaminated wastewater from undersea drilling and fracking are produced each year.
The new sponge developed by the team can remove up to 90% of the oil droplets from the wastewater in ten minutes. When sponges are used, the team says, oil covers its surface like a thin film through a process called adsorption. After use, the sponge can be treated with a solvent to release oil from the sponge. Oil can be recycled and sponges can be used again.
The new sponge is a second-generation product with slightly less efficiency than the first generation of sponges. The first generation sponge can remove 95% of the oil, but it takes three hours to remove it. The new sponge can only remove 90% of the contaminants, but its ten-minute removal time is industrially useful. The pH range of the new sponge is also larger than that of the previous sponge.
Scientists used polyurethane foam in the first generation of sponges to separate tiny droplets from wastewater. The second generation sponge improvement design involves adding tiny nanocrystalline silicon. These particles allow the sponge to capture and retain the oil droplets and form a coating on the surface of the hole, a process known as critical surface energy, so that the droplets are tightly grasped. In the future, the team hopes to use sponges to perform other tasks, such as removing bacteria from salt water and treating other types of contaminants.