Suction or gravity-fed oil-water separation using PDMS-coated glass filters

The environmental hazards caused by oil-contaminated water has led to many research efforts in pursuit of high efficiency, low-cost methods which can effectively separate oil and water, with separation efficiencies that can exceed 99%. One promising route is the use of superhydrophobic materials which can allow for selective separation, due to the differences in chemical properties between oil (hydrophobic) and water (hydrophilic). Here, we present a simple and cost-effective PDMS-coated superhydrophobic filter that has been developed to separate liquids, both under the influence of gravity and via suction pressure. By varying the initial filter porosity and polymer coating thickness, the physical resilience and flux of the filter could be controlled and tailored to the intended application. The best performing filters were shown to have high separation efficiencies (> 98%), in addition to exhibiting the possibility for high fluid flux (up to 7504 L.m−2.h−1). The filters reported here displayed great potential for use in many application areas that require the separation of oils from water, either through straightforward filtration or integration into specialised devices.