3D Janus sponge with controllable pore size for stable separation of oil-water emulsion and dye contaminants

The development of separation materials with high flux, anti-oil fouling, long-term stability, and the ability to remove various pollutants is an urgent requirement in the field of oil-water separation. Herein, we designed a Janus sponge with multiple separation functions. Specifically, we first prepared the PCA-CS gel coating on the polyurethane (PU) sponge through the co-deposition of protocatechuic acid (PCA) and chitosan (CS), and then Janus sponge was obtained through bottom-up approach of adsorbing stearic acid (SA) and an ethanol suspension of titanium dioxide (TiO 2 ). The prepared Janus sponge exhibits excellent wetting behavior and oil adhesion resistance, and can maintain stable performance in acidic, alkaline, saline solutions and ultrasonic environment. The pore size of the Janus sponge can be adjusted by mechanical compression to efficiently separate various types of emulsions, dyes and mixed wastewater. Among them, the emulsion and dye separation efficiency can both be above 99.6 %, and can maintain the high flux with 15372.7 L m −2 h −1 . More importantly, the prepared Janus sponge can effectively remove the emulsified oil droplets from the wastewater generated by the automotive final assembly shop. Consequently, it can be predicted that Janus sponge exhibits great application potential in emulsion and dye wastewater treatment.