A mixed matrix membrane for butanol pervaporation based on micron-sized silicalite-1 as macro-crosslinkers

Herein, we report a method for the fabrication of an efficient membrane for butanol recovery from dilute aqueous solution using micron-sized particles of surface modified silicalite-1 as macro-crosslinkers within a polydimethylsiloxane (PDMS) matrix. In this work, silicalite-1 of nano- and micron-sized particles were synthesized and surface modified with a range of alkyloxysilanes in the fabrication of mixed matrix membranes (MMMs) in order to minimize the undesirable voids. Moreover, silicalite-1 particles in MMMs have a double function which not only provided transport channels of high selectivity, but also reacted with the hydroxyl groups of PDMS during membrane formation. The highest separation performance was obtained by incorporating micron-sized n-propyltrimethoxysilane (PTMS)-modified silicalite-1 into the PDMS membrane at a loading of 63 wt%. A high separation factor of 72.9 and a normalized total flux of 1156 g/m2h were obtained in separating n-butanol from a 1.5 wt% aqueous solution at 55 °C. Compared to the pure PDMS membrane, the separation factor and normalized butanol flux were increased by 83.6% and 19.7%, respectively. Most importantly, having a very high separation factor and flux, the optimized mixed matrix pervaporation membrane developed here may enable the economically viable production of n-butanol from fermentation feedstock.