Solvent resistant nanofiltration (SRNF) membranes based on metal-organic frameworks

The incorporation of metal-organic frameworks (MOFs) as fillers in polydimethylsiloxane (PDMS) membranes was investigated. Mixed matrix membranes (MMMs) with MOFs [Cu3(BTC)2], MIL-47, MIL-53(Al) and ZIF-8 as dispersed phases were synthesized and characterized. The membranes were applied in solvent resistant nanofiltration (SRNF), more in particular in the separation of Rose Bengal (RB) from isopropanol. The membranes showed increased permeance but lower retention compared to unfilled membranes. Membranes were characterized with scanning electron microscopy (SEM) where poor adhesion of the fillers to PDMS was observed. Chemical modification of the fillers with N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA) allowed synthesis of defect-free membranes with higher retention of RB, due to good interaction with fillers and decreased membrane swelling.