A high ZIF-8 loading PVA mixed matrix membrane on alumina hollow fiber with enhanced ethanol dehydration

Abstract

In this work, a zeolitic imidazolate framework-8 (ZIF-8)/polyvinyl alcohol (PVA) mixed matrix membrane (MMM) was coated onto α-aluminum oxide (α-Al2O3) hollow fibers for ethanol dehydration by utilizing the pervaporation technique. ZIF-8/PVA solution was prepared via a drying-free, water-based method to obtain a uniform distribution MMM. Before coating the MMM onto the hollow fiber, a pristine PVA solution was first dip-coated onto hollow fiber as a gutter layer to prevent phase separation. Different weight ratios of ZIF-8-loaded MMMs were prepared. The results showed that at high ZIF-8 loading (39 wt %), a high permeate flux (685 g/m2 h) and high separation factor (4821) can be observed. Furthermore, compared with free-standing ZIF-8/PVA MMMs, hollow fiber supported ZIF-8/PVA MMMs exhibit a thinner coating thickness but higher pervaporation separation index (approximately 1.5–2 times). The main contribution of this study is not only fabricated the high loading ZIF-8/PVA composite membrane with enhanced performance, but also coated onto the hollow fiber membrane which opens a gate for scale-up production.