Effects of PEG Molecular Weights on PVDF Membrane for Humic Acid-fed Ultrafiltration Process

This paper reports the performance and characterization of asymmetric PVDF ultrafiltration flat sheet membranes with polyethylene glycol (PEG) of different molecular weight as additives. The membranes were prepared via phase inversion technique by using DMAc as solvent and polyethylene glycol with molecular weights of 2000, 6000 and 20000 Da as additives in the dope formulation. The performance of membrane was characterized using humic acid as natural organic matter source. Membrane properties were evaluated in terms of pure water flux, and humic acid rejection. The results indicated that the pure water flux of membranes increased with the increase of PEG molecular weights. Fourier transform infrared spectroscopy results revealed the presence of PEG in the PVDF/PEG membrane with the significant appearance of the N-CH₃ peak at 2877 cm^-1. Scanning electron microscopy analysis was performed to investigate the effects of additives on the morphological structure of the membrane. It was disclosed that the porosity of the resulted membranes increased with the addition of PEG.