Preparation of polymer blend membranes based on cellulose acetate and quaternized polyethersulfone for ultrafiltration

Abstract

Aim: The present study was aimed to develop the ultrafiltration (UF) membranes were prepared from blends based on cellulose acetate (CA) and quaternary ammonium salt of polyethersulfone (QASPES) at various compositions. Materials and Methods: All membranes were prepared by the diffusion-induced phase separation method, namely casting a thin film of the polymeric solution on a glass plate and, after allowing the solvent to evaporate for a predetermined period at the desired humidity and temperature conditions, immersing it into a bath of non-solvent (water, solvent, and surfactant) for final precipitation. Before membrane casting, a gelation bath of 2 L of distilled water (non-solvent), containing 2% N,N-dimethyl formamide (DMF) (solvent) and 0.2% sodium lauryl sulfate (surfactant) was prepared and cooled to 10°C. Results and Discussion: QASPES conformed by Fourier transform infrared and nuclear magnetic resonance. The blend membranes prepared are characterized in terms of compaction time, pure water flux, water content, and scanning electron microscopy. It is observed that the surface hydrophilicity of the CA-QASPES blend membranes has enhanced remarkably with increase of QASPES content. During compaction study, the steady-state flux is reached within 3–4 h at 414 kPa pressure. Pure water flux and water content of the membranes are found to increase, especially when QASPES content in CA membrane is simultaneously increased. Cross-section morphology of the membranes is analyzed using scanning electron microscope. Conclusion: We conclude that the incorporation of the hydrophilic moiety (QASPES) in blend membranes plays a major role in improving the flux and performance characteristics of membranes. The proposed techniques would be economical, convenient, and safe.