Synthesis and characterization of high-flux ZIF-90/poly-dimethyldiethoxysilane (PDMDES) mixed matrix membrane for enhanced pervaporation recovery of alcohols

In the present research, micron-sized zeolitic imidazolate framework-90 (ZIF-90) particles were synthesized utilizing an adapted synthesis route and subsequently incorporated into the poly-dimethyldiethoxysilane (PDMDES) polymer to fabricate ZIF-90/PDMDES mixed matrix membrane (MMM) with an objective to achieve enhanced pervaporation performance for the efficient separation of alcohols from aqueous solutions. Comprehensive characterization techniques were employed to investigate the properties of the ZIF-90 particles and the newly fabricated ZIF-90/PDMDES MMMs. Encouraging findings revealed that the incorporation of microporous ZIF-90 particles led to notable enhancements in hydrophobicity, alcohol affinity, and thermal stability of the MMMs. Notably, a distinctive cross-sectional morphology of the ZIF-90/PDMDES MMMs were observed at lower ZIF-90 loadings, a phenomenon attributed to the disparity between the ZIF-90 particle size and the inherent thickness of the PDMDES layer. Systematic evaluations were conducted to ascertain the influence of ZIF-90 loadings, feed concentration, and operational temperature on the pervaporation performance of ZIF-90/PDMDES MMMs. Accordingly, the optimal separation performance was obtained at the ZIF-90 loading of 5 wt% when separating ethanol from 5 wt% ethanol aqueous solution at 40 °C, yielding an impressive total flux of 6.51 kg∙m⁻² h⁻¹, a separation factor of 7.29, a PSI of 40.95 kg∙m⁻² h⁻¹, and an ethanol permeability of 7.45 × 10⁴ Barrer.