Improved microfiltration and bacteria removal performance of polyethersulfone membranes prepared by modified vapor‐induced phase separation

Polyethersulfone (PES) microfiltration membranes were fabricated by a combined vapor‐induced phase separation and wet phase separation method. The effect of different non‐solvent additives in casting solution, ie, acetone, diethylene glycol, and triethylene glycol (TEG) was investigated on the membrane morphology and performance. Scanning electron microscopy images showed that the membrane containing TEG additive had a skinless symmetric structure with well interconnected pores. The permeability of the PES/PVP/TEG membranes increased by decreasing PES and TEG and increasing PVP concentration. Bacteria removal performance of the prepared membranes was investigated by the filtration of E. coli suspension. The membrane made from casting solution containing 15 wt.% PES, 16 wt.% PVP, and 20wt.% TEG showed a pure water flux of ~ 5370 L/m² h at low transmembrane pressure of 10 psi and 100% bacteria removal efficiency. The results of in vitro cytotoxicity test and cell viability assay showed non‐toxic nature of the prepared membranes.     

Monitoring of Vapor-Induced Phase Separation during Spin Coating of PVDF by Optical Scattering

Solutions of poly(vinylidene fluoride) (PVDF) and dimethyl sulfoxide (DMSO) were spin cast under varying relative humidity environments. To elucidate film formation mechanisms, in situ optical scattering was used to monitor the physical processes occurring during spin coating. SEM micrographs and optical scattering taken together show that vapor-induced phase separation (VIPS) is a process that controls morphology during spin coating. Time periods were identified in the optical scattering patterns allowing for real time identification of phase separation for greater process control.