Design of an Organic-Inorganic Amine Monomer to Prepare Thin Film Composite Membranes for Bioethanol Purification

A novel hybrid organic-inorganic amine monomer has been designed and synthesized to prepare thin film composite (TFC) membranes for bioethanol dehydration via pervaporation. Different from the conventional amine monomer, m-phenylenediamine (MPD), used for interfacial polymerization, the new monomer was molecularly designed to sandwich an inorganic component nonafluorohexylmethyldichloro silane (ClSi) between two MPD molecules. Nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectrometry were used to characterize and verify the chemical structures of the new monomer and the polyamide film. As a result, the advantages of polymeric and inorganic materials are effectively integrated in the newly developed TFC membranes, and these membranes exhibit a superior pervaporation separation performance as compared to most reported membranes in the literature for ethanol dehydration. Their best pervaporation performance shows a flux of 1.9 kg/m²-h and a separation factor of 108 for the dehydration of the 85/15 wt% ethanol/water mixture at 50 °C. These novel TFC membranes show a great potential to compete with commercially available membranes.