Phase Inversion Synthesis of PEI/PSf Membranes: Role of DMF and NMP in Morphology and Water Flux

Due to the increasing scarcity and pollution of water resources suitable for drinking water supply, conventional treatment methods are becoming insufficient, which in turn increases the need for advanced treatment technologies. Among these advanced methods, membrane processes are of particular importance. A membrane is a selectively permeable material that separates two homogeneous phases. Membrane processes offer some advantages as having smaller footprint, high-quality effluent water, reduced construction requirements, and lower consumption of chemical additives. However, there are disadvantages such as membrane fouling and relatively high initial investment and operational costs. Therefore, research and development studies on membrane production are rapidly progressing. In this study, phase inversion method was used to synthesise flat-sheet UF membranes with 15 wt% Polyetherimide (PEI) and 15 wt% Polyethersulfone (PSf) as polymers, and 85 wt% 1-Methyl-2-Pyrrolidone (NMP) and 85 wt% 1,1-Dimethyl formamide (DMF) as solvents. The effects of NMP and DMF solvents on the morphology and permeability of membranes synthesised with PEI and PSf polymers were investigated.The synthesised membranes were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy (FT/IR), contact angle measurement, viscosity, water retention capacity, and porosity analysis. In addition, the distilled water and lake water flux performances of the membranes were evaluated. As a result of the study, it was observed that when compared to DMF, hydrophilicity was enhanced and the permeability performance of the membranes were increased with the use of NMP.