Metal-assisted multiple-crosslinked thin film composite hollow fiber membrane for highly efficient bioethanol purification

Abstract

Polyamide (PA)-based thin film composite (TFC) membranes have been extensively applied in various membrane-based separations. However, research works for bioethanol purification are relatively limited due to insufficient hydrophilicity and chain packing density of the PA selective layer by conventional interfacial polymerization. In this work, a new TFC hollow fiber (HF) membrane is fabricated by metal-assisted multiple crosslinking strategy, that is, metal-coordinated crosslinking of the pristine PA layer and coordination complexation between metal ions and phytic acid (PhA) for advanced water/ethanol separation. By tuning coordination abilities of metal ions with PA and PhA and the cycle number of PhA/metal ion assembly, PA-based TFC HF membrane is perfected. Additionally, a joint experiment/simulation characterization is deployed to reveal the coordination abilities of various metal ions with the pristine PA and grafted PhA. Ultimately, the synergistic effect between PA layer and PhA-metal ion complexes (i.e., 1 + 1 > 2 effect) is embodied in the separation performance of water/ethanol separation. The resulting TFC-Fe3+-PhA membrane with the strongest PhA-metal ion coordination ability exhibits the best water/ethanol separation performance, i.e., the separation factor of 1703 (34 times higher than pristine PA TFC HF membrane) and total flux of 1705 g/m2 h. This metal-assisted multiple crosslinking strategy is therefore believed to shed important lights on the development of next-generation high-performance TFC membranes for bioethanol purification.