Researchers developed a low-cost membrane that can efficiently separate oil and water, according to a study conducted on May 25, 2018.
This study was conducted by the researchers at the University of British Columbia. This development will aid in faster cleanups of oil spills and improved treatment of industrial wastewater in the future.
By applying a small voltage using a regular alkaline battery, the copper mesh of the membrane can be switched from oil-removal to water-removal mode. When the membrane is in the oil-removal mode, water is retained and heavy oil is allowed to pass through the mesh. In water-removal mode, the mesh allows water to pass through while retaining light oil. Therefore, this switching mode makes it easier for the user to achieve almost complete separation of both light and heavy oils from water using a single membrane.
There are other membrane treatments with similar mechanism. However, those methods often rely on toxic, unstable chemical coatings that take time to activate. Also, the separation is not as accurate as in this method. Chun Haow (Bryan) Kung, a chemical engineering master’s student at UBC said, “Our membrane is free of additives and is capable of achieving at least 98 per cent purity for the separated oil and water. It needs a single electrical charge to switch operations, and requires no special equipment or conditions.”
For the preparation of the membrane, a simple copper mesh was initially immersed in an electrolyte solution. Then, two small voltages were applied for a total of two minutes. The surface structure of the mesh is changed by this process and it will be able to switch back and forth from attracting water and repelling oil to attracting oil and repelling water. Furthermore, researchers put the membrane through 30 consecutive separation cycles to test the robustness of the mesh.