Superhydrophobic polyvinylidene fluoride microporous membranes via combining TIPS with rolling embossing: the influence of pre-evaporation

Superhydrophobic microporous membranes hold great promise for applications in membrane contactor processes and oil-water separation, and it is crucial to develop a simple method to prepare stable superhydrophobic membrane. We investigated the impact of pre-evaporation time on membrane performance during the preparation of superhydrophobic membranes, employing a combination of TIPS with rolling embossing. To ensure the success of the roll pressing process, we initially conducted pre-evaporation experiments to determine the optimal pre-evaporation time. Subsequently, the embossed membranes underwent comprehensive characterization using SEM, XRD, AFM, contact angle measurement, porosity analysis, pore size determination, N2 flux measurement, and assessment of mechanical stability. The surface of the embossed membrane showcased a micron-submicron hierarchical structure reminiscent of the lotus leaf surface, resulting in a high water contact angle (WCA) of 151° and a low solid contact angle (SA) of 9.5°. Furthermore, the embossed membrane exhibited favorable porosity, pore size, N 2 flux, and liquid entry pressure (LEP). The micro-submicron hierarchical structure demonstrated excellent mechanical stability. Ultimately, the embossed membranes demonstrated remarkable separation efficiency and operational stability in emulsion separation. Even after 20 cycles, the PVDF micropores maintained a high flux of 982.10 L•m − 2 •h − 1 and a retention rate (α) of 98.67%. Notably, the embossed membranes effectively removed 100% of mechanical impurities and water from waste diesel fuel.