Mixed Matrix Membranes Comprising of PDMS an Deep Eutectic Solvents Infused ZIF-8 for Ethanol Dehydration

Abstract

Mixed matrix membranes (MMMs) specially based on MOFs have shown remarkable separation performance in the past few years. To improve the performance of selective membranes fillers are being modified using different techniques. Direct incorporation of inorganic fillers in MMMs usually results in a poor polymer-filler interaction and unselective voids. To overcome this problem, deep eutectic solvent (DES) has been extensively used as a wetting agent. In this study an inorganic filler Zeolitic imidazolate framework-8 (ZIF-8) was used due to its appropriate pore size, selective property and shape. The properties of ZIF-8 were further enhanced by making a composite of ZIF-8 with a DL-Menthol and Lauric Acid-based DES. DES infused ZIF-8 was then used as a filler to fabricate MMMs. Polydimethylsiloxane (PDMS) was used as polymer matrix. FTIR results confirm DES impregnation over ZIF-8 particles. The efficiency of MMM for ethanol dehydration was assessed in a pervaporation set up at various temperatures and feed conditions. Hydrophobic properties of DES along with the nanoporous structure of ZIF-8 and large surface area provided by ZIF-8, has improved the membrane performance for alcohol dehydration. With the increase in % loading of filler the flux increases as well. MMMs loaded with 10 wt% of ZIF-8 infused DES demonstrated an increase in flux and a 50% reduction in activation energy as compared to pristine PDMS membrane