The in-situ synthesis of a high-flux ZIF-8/polydimethylsiloxane mixed matrix membrane for n-butanol pervaporation

In pervaporation processes, membranes with high flux can relief the cost issue of industry scaling-up due to the required smaller membrane area. Herein, a novel in-situ synthesis (ISS) method was adopted to fabricate ZIF-8/polydimethylsiloxane (PDMS) mixed matrix membranes (MMMs) with outstanding permeability. ZIF-8 with high hydrophobicity, benefiting from its flexible pore structure, can provid a suitable pore structure for selectively recovering organic compounds. In the membrane preparation process, the solution C (PDMS/tetraethyl orthosilicate/Zn2+) and solution D (PDMS/dibutyltin dilaurate/2-methylimidazole) were co-processed other at the C-D interface via spin-coating. ZIF-8 crystallization occurred coupled with PDMS polymerization. An effective active layer was formed including (i) continuous and defect-free PDMS layer and (ii) a ZIF-8/PDMS layer that can add passable diffusion channels, which lifted the barrier of physical incorporation of porous materials. Defect-free MMMs based on ISS method possess unprecedented total flux of 2046.3 g/m(2) h (1.6 times higher than pure PDMS membrane) and without any decline in separation factor under 20 wt% ZIF-8 loading for n-butanol pervaporation recovery. The ZIF-8/PDMS MMM prepared by ISS method showed promising in n-butanol separation.