Morphology and performance of pvdf membranes composed of triethylphospate and dimethyl sulfoxide solvents

This study investigated the impact of different solvents on the characteristics and filtration performance of polyvinylidene fluoride (PVDF) membranes. PVDF membranes were fabricated via the non-solvent induced phase separation (NIPS) technique by dissolving 20% w/w PVDF in triethyl phosphate (TEP) and dimethyl sulfoxide (DMSO), separately. The Hansen solubility parameter was studied as the kinetic aspect that influences membrane formation. The characteristics of the membranes were investigated including the membrane morphological structure, surface roughness, chemical group composition, and tensile strength. The filtration performance of the resulting membranes was also conducted using cross-flow filtration including pure water permeability (PWP), synthetic CaCO3 suspension rejection, and membrane recovery after long-term filtration. The experimental results showed that DMSO has a closer solvent affinity with the non-solvent resulting in a membrane with higher porosity than the TEP membrane with a denser structure. Furthermore, the PVDF/DMSO membrane also had higher PWP than the PVDF/TEP membrane. However, in terms of the filtration performance of the CaCO3 suspension, the PVDF/TEP membrane showed the best performance with higher flux permeation, better flux recovery of up to 96.6%, and the highest solute rejection reaching 100%. The analysis of the experimental results are discussed further.