Hierarchical composite membrane with multiscale roughness structures for water-in-oil emulsion separation

Abstract A hierarchical structure composite membrane, which consisted of a polyvinylidene fluoride (PVDF) nanofiber selective layer, a polymethyl methacrylate (PMMA) microspheres layer, and a polyacrylonitrile (PAN) nanofiber support layer, was successfully fabricated by electrospinning. The morphology, mechanical property, wettability and the water-in-oil (W/O) emulsion separation performance of the electrospun PAN-PMMA-PVDF membranes were investigated. The mechanism of W/O emulsion separation was clarified. The results indicated that surface roughness of the composite membrane can be manipulated by changing the concentration of PMMA spinning solution (8-14 wt%). The PAN-PMMA(12)-PVDF membrane was determined to be a suitable material based on the separation performance for W/O emulsion. Furthermore, the membrane with the water contact angles of 131°, showed a good tensile strength and flexibility, fast oil permeability, and high hydrophobicity. More importantly, this membrane had high porosity (85.1%), which exhibited high flux (2408 L·m−2·h−1) and good separation efficiency (92%) for methylbenzene, as well as the good reusability. Overall, this study provides a way to fabricate nanofibrous mats with hierarchical structure and multiscale surface roughness. The proposed membranes are viable alternatives for W/O emulsion separation with high efficiency.