Intelligent device composed of two membranes with opposite wettability for identification and purification of both water and oil phases from oil-in-water and water-in-oil emulsions

Oil/water separation based on superwettable materials has been a fast-growing field due to the economical, energy-efficient separation process but superior separation efficiency. Nevertheless, the separation of compli-cated oil/water systems that may contain oil-in-water and water-in-oil emulsions in one batch, which actually is of great importance for true applications, has not been explored. Herein, we created an intelligent device composed of two porous membranes with opposite superwettability, e.g., one of them displays super-hydrophobicity/superoleophilicity, whereas the other shows superhydrophilicity/underwater super-oleophobicity. Highly efficient separation and purification of both water and oil phases from complicated oil/ water systems can be achieved by the integration of two membranes with opposite superwettability in one single device. The oil-in-water and water-in-oil emulsions can be automatically identified and purified by the right membrane due to their suitable wettability, which avoid the failure of the separation for unknown type of emulsion. Consequently, clean water and oil can be obtained only through a single operational unit using such a separation device. This work paves the way toward true industrial applications related to oil/water separation in which the type or composition of the oil/water systems may change from time to time.