Fabrication of asymmetric and symmetric membranes based on PES/PEG/DMAc

Phase inversion is one of the main techniques for fabrication of asymmetric structural membranes and occasionally for the formation of a symmetric structure. Microporous membrane has been utilized for size-selective filtration in sample pre- or post-treatment applications. In this study, symmetrical or sponge-like membrane with highly interconnected pores based on polyethersulfone (PES) was fabricated via a combination of phase inversion techniques. The membrane pore sizes and distributions were controlled in the microfiltration range and the effects of humidity and polyethylene glycol (PEG) as a pore-forming agent on membrane morphology were investigated. Scanning electron microscopy (SEM) used to evaluate membrane cross section morphology, the porosity was calculated through the liquid immersion method, and pure water flux (PWF) was measured in a dead-end apparatus. We found that the humidity and pore-forming agent have a great impact on the formation of fully sponge-like structure in PES-based membrane. The results confirmed that by introducing PEG as pore-forming agent the sponge-like structure forms and molecular weight of additives as well as humidity alters the membrane morphology. Being located in a moist environment before immersion in non-solvent bath and after addition of PEG with different molecular weight (M W) will change the morphological structure of PES-based membrane, flux and retention properties. For nominal sample, the water permeability and porosity were 490.57 L/m2h and 90.39 %, respectively. Eventually the application of this membrane was investigated to determine the optimal potential in microorganisms filtration.