High Flux Membranes for Organic Solvent Nanofiltration (OSN) - Interfacial Polymerization and Solvent Activation

M.F. Jimenez Solomon, Y. Bhole, A.G. Livingston
Imperial College London, UK

Keywords: organic solvent nanofiltration, solvent resistant, thin film composite membranes, interfacial polymerization, hydrophobic, surface modification, solvent activation

Summary:

Organic Solvent Nanofiltration (OSN) is an emerging technology for molecular separation and purification processes. A challenge in nanofiltration and reverse osmosis is to broaden the applications from aqueous to organic feeds. This requires solvent stable membranes that preserve their separation characteristics under a large range of solvents. Using integrally skinned (IS) asymmetric membranes we have difficulties controlling the structure of the top layer, which controls selectivity, flux and separation. One way to solve this problem is to make the top-layer in a separate step using alternative chemistries, resulting in Thin Film Composite (TFC) membranes, which have key advantages compared to IS asymmetric membranes. Here, polyimide UF membranes were used as supports for the formation of OSN TFC membranes by interfacial polymerization (IP). Promising results have been obtained by varying different parameters on the formation of the top-layer, enhancing flux and rejection. These novel OSN TFC membranes show good rejection, and dramatically improved permeabilities in different organic solvents, including DMF and THF. Finally, to further improve flux for non-polar solvents, different chemistries have been used, successfully enhancing flux in hydrophobic solvents; including Toluene. These are the first OSN TFC membranes prepared via IP stable in DMF.