Low pressure high flux thin film nanofibrous composite membranes prepared by electrospraying technique combined with solution treatment

In this study, high flux thin film nanofibrous composite (TFNC) membrane consisting of a nonwoven nanofibrous supporting layer and a thin hydrophilic barrier layer was developed and used as an ultrafiltration media to separate an oil/water emulsion at low feeding pressure. Firstly, the hydrophilic barrier layer was fabricated by electrospraying polyvinyl alcohol (PVA) on nanofibrous polyacrylonitrile (PAN) substrate. Secondly, the deposited PVA top layer was swollen to merge imperceptibly into an integrated barrier film on the supporting layer by immersing PVA/PAN double-layer membranes into suitable solvent water and nonsolvent acetone mixture, and then chemically crosslinked by glutaraldehyde in water/acetone solution. The water content of water/acetone solution and the immersion time were optimized to achieve the integrated and nonporous PVA barrier layer. Filtration performance of the resulting PVA/PAN TFNC membranes was evaluated by the oil/water emulsions separation system. Results showed that the optimized TFNC membrane possessed high flux (347.8 l/m2 h) with high rejection rate (99.6%) at very low feeding pressure (0.2 MPa). It is believed that the strategy for fabricating TFNC membranes described here can be extended easily to fabricate TFNC membranes from many other polymeric membrane materials simply by choosing the suitable solution system for post-treatment.