Novel simultaneous oil-water separation strategy with Janus membrane via integrating two opposite wettability microfibers

In the realm of oil-water separation, a prevalent issue is the inherent limitation of most materials to exhibit either hydrophilicity or lipophilicity. This singular affinity impedes the seamless separation of light oil/water and water/heavy oil mixtures. Although some materials have been identified to exhibit Janus wettability—encompassing both lipophilic and hydrophilic properties—further refinement of experimental strategies is essential to accommodate the diverse requirements of separating these mixtures. Our research introduces an innovative approach by mechanically grinding fibers to create two microfibers with distinct wettabilities. Subsequently, an interdigital Janus microfiber membrane (IJMM) was crafted through a filtration process. This IJMM demonstrated exceptional efficiency in the continuous separation of the three-phase system involving light oil, water, and heavy oil, achieving average separation rates of 94% for light oil, 96.7% for water, and 93% for heavy oil. This development effectively addresses the challenge of needing to modify conditions for the separation of various oil/water mixtures. Moreover, we formulated a mixed oil (MO) with a density comparable to that of water for separation, which was designed to replicate the non-stratified conditions of oil and water in complex environments. The IJMM was capable of efficiently and simultaneously separating the MO/water mixtures, with average separation efficiencies of 98.7% for MO and 96.7% for water. Consequently, our membrane via integrating two opposite wettability microfibers presents a novel strategy for the continuous and simultaneous separation of light oil/water/heavy oil mixtures, offering promising prospects for oil-water separation in complex applications with non-stratified conditions.