Researchers in China have made a new type of membrane that can separate oil from water and could potentially be used in oil spills, such as the one in the Gulf of Mexico. The membrane works by interacting differently with the substances as it is both superhydrophobic and superoleophilic, so that it repels water but attracts oil. This means that the oil is absorbed through the membrane, but the water can’t penetrate.
The membrane is made from a polymerised fluorinated polybenzoxazine (F-PBZ) layer on top of cellulose acetate nanofibres. The scientists used an electrospinning technique (in which a viscous liquid is passed through a conducting needle to form a thread) to create a porous structure that makes the membrane even better at absorbing the oil.
Bin Ding from Donghua University leads the team that developed this technology. He explains that one of the best things about their membranes is that they are stable and can be used over a wide pH range, making them suitable for use in a variety of challenging environments. The complex surface of the membrane gives it a surface area of 58.96m2/g. Ding comments that ‘currently, there are no other membranes with such a high surface area for oil spill clean-up’.
John Howarter, an expert in polymer membranes from Purdue University, US, thinks this research is a significant achievement. ‘The performance of their materials is remarkable with the extreme contact angle difference between the oil (at 3 degrees) and water (161 degrees),’ he says. ‘Technology such as this is useful for dealing with large scale environmental problems, but could also be used in a manufacturing setting.’
Ding’s team’s use of simple techniques will make it possible for them to produce their membranes on a larger, industrial sized, scale in the future, but first they will be improving the structure of the membranes to fine tune their performance. They are also working on other F-PBZ hybrid fibrous membranes to see what else they can do with them.