Hydrophobic modification of PVDF membranes for biodiesel purification

In this study, Nafion (R) solution was utilized to modify the surface of commercial polyvinylidene fluoride (PVDF) membrane in order to enhance the hydrophobicity of membrane for biodiesel purification. In order to modify the membranes, the commercial PVDF membranes were dipped in Nafion (R) solution for different coating times (0, 3, 5, 7, 10 min) at constant pressure and temperature. The modified membranes were characterized by Fourier transform infrared spectroscopy (FTIR) spectra, contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy and purification experiments. The presence of Nafion (R) functional groups in the membrane structure was indicated by FTIR spectra at around 1970 cm(-1) 1057 cm(-1). The contact angle measurements exhibited that the surface contact angle of the membranes was increased by increasing the coating time in the Nafion (R) solution. The SEM images showed that coating the Nafion (R) solution caused a reduction in porosity, pore size and surface roughness of modified membrane. This reduction was increased with increasing in coating time in Nafion (R) solution. Thus, the denser membrane with less porosity was produced for modified PVDF membranes. The modified membranes were applied for purification of biodiesel produced from canola oil using dead end filtration cell. The results show that the yield of biodiesel production was increased with increasing in coating time while biodiesel flux was decreased.