Poly-Vinylidene Fluoride (PVDF)/ Span-85 Membrane for Omega-3 PUFA Concentration: Membrane Performance and Fouling Analysis

For increasing the efficiency of the omega-3 production, the effect of span-85 surfactant as a hydrophobic agent (0, 1, 2, 3 and 4 wt%) on the formation of a porous structure in a sub-layer PVDF membrane was studied. Also, the cross-sectional morphology of PVDF membranes was analyzed using scanning electron microscopy (SEM) and the surface property was evaluated using contact angle test. The capacity of the membranes to concentrate omega-3 was examined by the filtration of lantern fish oil. Also, the fouling of the membrane caused by oil filtration was evaluated. All filtration tests were performed in batch mode. Results of the SEM images demonstrated that the addition of span-85 resulted in the forming of a membrane with a denser and more hydrophobic structure. The addition of 2 wt% span-85 increased the omega-3 concentration, while the higher level of span-85 showed a negative effect. The best efficiency of the membrane was 42.64 wt% which was obtained by PVDF/2 wt% span-85. This efficiency was about 11% higher than the control PVDF (0 wt%). Taken together, the presence of span-85 affected the phase inversion process during the membrane formation, which improved omega-3 concentration. Moreover, the more hydrophobic surface of the membrane resulted in higher cake formation.