Transition sandwich Janus membrane of cellulose acetate and polyurethane nanofibers for oil–water separation

Through sequential electrospinning, a sandwich Janus membrane (PU-(CA/PU)-CA) was constructed with hydrophobic polyurethane (PU) nanofiber membrane as the top layer, cellulose acetate/polyurethane (CA/PU) blend nanofiber membrane as the intermediate transition layer and hydrophilic cellulose acetate (CA) nanofiber membrane as the bottom layer. The effects of membrane structure, composition and thickness on the mechanical properties, permeability and separation ability of PU-(CA/PU)-CA nanofiber membrane were studied. The results show that the transition sandwich structure PU-(CA/PU)-CA membrane has good mechanical properties, high permeability and selective separation ability, and can realize the unidirectional transmission of water and efficient oil–water separation. When the membrane thickness is 80 μm, the hydraulic permeability is 3.4 ± 0.4 × 10 4 L/(m 2 h bar), the oil–water separation efficiency reaches 99 ± 0.4%, and the tensile strength is 95.8% higher than that of the double-layer PU-CA membrane. The thermal stability and antifouling ability of PU-(CA/PU)-CA nanofiber membrane have also been improved, and the reusability is good. CA/PU transition interlayer improves the interfacial compatibility between CA and PU nanofiber membrane, enhances the performance of PU-(CA/PU)-CA nanofiber Janus membrane, and shows its application prospect in the field of separation and purification. Graphical abstract