Self-driven oil/water separator with super-high separation rate

Oil/water separation is of great significance due to the severe threats of oily wastewater to the environment and human health. However, the existing methods still cannot spontaneously and continuously separate the oil/water mixture with high rates and low costs. Here, a novel oil/water separation method based on a self-driven oil jet phenomenon was proposed to resolve the aforementioned problem. We designed a self-driven oil/water separator (SOWS) composed of an oil container with some oil and a water container with some water. The oil container, whose whole bottom was covered with underwater superoleophilic pores, underwater superoleophilic ring region, and other underwater superoleophobic region, was fixed in the water container. The underwater oil droplet was easily captured by the superoleophilic region and spontaneously penetrated the pore, generating an oil jet. The resultant force from Laplace pressure and hydrostatic pressure drove the droplet to generate the jet and affected the droplet flow rate. Based on the self-driven oil jet and suitable optimization, the SOWS realized the spontaneous and continuous oil/water separation with the separation rate of 42929.4 L∙m−2∙h−1 which was much faster than the reported oil/water separation methods. Moreover, the SOWS could efficiently separate the oil/water mixture with different oil content and oil viscosity. This method shows an outstanding practical application prospect in the oily wastewater treatment.