For a long time, there has been a requirement to be able to separate oil from water quickly, when an off shore oil spill occurs. Now with Fracking – where pressurised water is used to release oil and gas from shale, becoming widely used, the need is becoming ever more acute. Scientists from Durham University have developed coatings that can achieve the required separation faster than previously.
In the past, clean up crews have relied on absorbent natural materials such as clay, straw and wool to mop up oil, the problem with these materials is that they soak up a lot of water at the same time, making them less than efficient. Further steps and equipment are then needed to remove the oil from the absorbent material, which is often difficult when aboard a ship.
In recent times researchers have tried new smart materials called “oleophobic-hydrophilic” coatings that let the water through and repel the oil. But to date these films have proved slow, taking up to several minutes to accomplish the separation. They have been described as complicated and poor at repelling oil.
The Durham based team developed oleophobic-hydrophilic coatings that they applied to metal mesh, similar to those used in screens for doors. In experiments they poured an oil-water mixture onto the mesh and saw that the water dripped through into the container below, while crucially, the oil remained on top of the mesh surface. They were then able to tilt the mesh so the oil went into another container. The separation was instantaneous and more efficient than existing films. The coating used was made in a single stage. The team also demonstrated that the coating could serve as an anti-fogging and selfcleaning film.