Development of hollow fiber membranes for solvent resistant nanofiltration
Lim, Siow Kee
Date of Issue2017-09-05
School of Civil and Environmental Engineering
Singapore Membrane Technology Centre
Solvent-resistant nanofiltration (SRNF) is an emerging membrane-based separation technology that can separate molecules of 200-1000 Da in various organic solvents efficiently. It has the potential to replace or be combined with traditional separation processes in industry to lower energy consumption and reduce waste. As hollow fiber membranes can offer advantages over flat sheet membranes and are not known to be commercially available for SRNF applications, this study aims to develop hollow fiber membranes that can perform nanofiltration in challenging polar aprotic solvents such as dimethylformamide (DMF) at a lower operating pressure than existing SRNF membranes. Polyamide-imide hollow fibers were fabricated by non-solvent induced phase separation and crosslinked using 3-aminopropyl trimethoxysilane (APTMS) so that they were stable in DMF. The crosslinked membranes were characterized by their gel content, swelling property, contact angle and mechanical properties. A conditioning treatment with either isopropanol (IPA) or deionized (DI) water was found to affect the morphology and performance of the membranes. Nanofiltration tests were carried out under 2 bar using Rose Bengal (1017 Da) in IPA and DMF. The membranes were tested in continuous operation for 7 days and stable performance in terms of flux and rejection could be attained, showing their potential to be applied in SRNF processes effectively.