Fabrication of blend polyvinylidene fluoride/chitosan membranes for enhanced flux and fouling resistance

The fabrication of polyvinylidene fluoride (PVDF) membranes was studied using chitosan as a hydrophilic additive for flux enhancement and stability. Chitosan (CS) was blended with PVDF at 0.5, 1.0, 1.5, 2.0 and 2.5% (w/w) concentration, to prepare mixed matrix membrane using the phase inversion method. CS presence within the polymer matrix was confirmed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The fabricated membranes were also analyzed for their structural and surface characteristics, including pore size distribution, porosity, contact angle, wettability and surface roughness. The water contact angle of the membranes has decreased upon the addition of CS. However, the wettability of the membranes was affected more profoundly due to an increase in their pore size. Microfiltration tests showed that the addition of CS was helpful in the reduction of fouling by bovine serum albumin (BSA). However, membranes with CS content higher than 1.0% endured surface micro-ruptures during the filtration tests due to swelling resulting from high water uptake. This simple method of fabrication of PVDF/CS membranes is a potential solution for the low flux and fouling of common PVDF microfiltration membranes. Furthermore, understanding the impact of CS on the fabricated membranes can facilitate the fine tuning of the membrane properties to achieve higher efficiencies.