PAN/PVA composite nanofibrous membranes for separating oil-in-water emulsion

In this work, nanofibrous membranes for separating oil-in-water (O/W) emulsion were prepared by electrospinning. The membrane material was polymer blend of polyacrylonitrile (PAN)/polyvinyl alcohol (PVA), and by adjusting polymer composition and concentration, as well as applying crosslinking by glutaraldehyde (GD ) and hydrolysis inside NaOH solution, membrane with desired properties, particularly hydrophilicity and underwater oil repellency were obtained. For PAN/PVA composite membrane modified by glutaraldehyde for 1.5 h and NaOH for 1.5 h, the water contact angle initially was around 5° and decreased to 0 o with a transition time of only 0.3 s. The membrane also showed recommendable performance in O/W emulsion separation. Under a driving force of 0.8 kPa, the highest starting flux of 953 L/m 2 h and 532 L/m 2 h were registered with the treatment of surfactant-free emulsion (SFE) and surfactant-stabilized emulsion (SSE), respectively. The membrane recovered 96% of its initial flux in a 5-cycle reusability test using SFE, and the oil rejection coefficient maintained higher than 97%. FTIR and XPS characterizations confirmed the success in chemical modifications. It was also found that glutaraldehyde crosslinking helped to improve the macroscopic structure integrity of the membrane in aqueous environment.