abstract: Membranes are a key part of pervaporation processes, which is generally a more efficient process for selective removal of alcohol from water than distillation. It is necessary that the membranes have high alcohol permeabilities and selectivities. Polydimethylsiloxane (PDMS) based mixed matrix membranes (MMMs) have demonstrated very promising results. Zeolitic imidazolate framework-71 (ZIF-71) demonstrated promising alcohol separation abilities. In this dissertation, we present fundamental studies on the synthesis of ZIF-71/PDMS MMMs. Free-standing ZIF-71/ PDMS membranes with 0, 5, 25 and 40 wt % ZIF-71 loadings were prepared and the pervaporation separation for ethanol and 1-butanol from water was measured. ZIF-71/PDMS MMMs were formed through addition cure and condensation cure methods. Addition cure method was not compatible with ZIF-71 resulting in membranes with poor mechanical properties, while the condensation cure method resulted in membranes with good mechanical properties. The 40 wt % ZIF-71 loading PDMS nanocomposite membranes achieved a maximum ethanol/water selectivity of 0.81 ± 0.04 selectivity and maximum 1-butnaol/water selectivity of 5.64 ± 0.15. The effects of synthesis time, temperature, and reactant ratio on ZIF-71 particle size and the effect of particle size on membrane performance were studied. Temperature had the greatest effect on ZIF-71 particle size as the synthesis temperature varied from - 20 to 35 ºC. The ZIF-71 synthesized had particle diameters ranging from 150 nm to 1 μm. ZIF-71 particle size is critical in ZIF-71/PDMS composite membrane performance for alcohol removal from water through pervaporation. The membranes made with micron sized ZIF-71 particles showed higher alcohol/water selectivity than those with smaller particles. Both alcohol and water permeability increased when larger sized ZIF- 71 particles were incorporated. ZIF-71 particles were modified with four ligands through solvent assisted linker exchange (SALE) method: benzimidazole (BIM), 5-methylbenzimidazole (MBIM), 5,6- dimethylbenzimidazole (DMBIM) and 4-Phenylimidazole (PI). The morphology of ZIF- 71 were maintained after the modification. ZIF-71/PDMS composite membranes with 25 wt% loading modified ZIF-71 particles were made for alcohol/water separation. Better particle dispersion in PDMS polymer matrix was observed with the ligand modified ZIFs. For both ethanol/water and 1-butanol/water separations, the alcohol permeability and alcohol/water selectivity were lowered after the ZIF-71 ligand exchange reaction. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2017

This research aimed to develop new composite membranes using a polymer of intrinsic microporosity (PIM-1) and metal organic frameworks (MOFs) for use in gas separations. PIM-1 was successfully synthesised using the high temperature method (40 min, 160 oC) and the resulting polymer was cast into membranes. PIM-1 membranes were chemically modified by reacting hexamethylenediamine (HMDA) with the nitrile group of PIM-1 to form HMDA-modified PIM-1 membranes. Surfaces of PIM-1 membranes were also modified by basic hydrolysis to form amide-modified PIM-1 membranes. These polymer materials were characterized by different techniques (GPC, NMR, ATR-IR, TGA, Elemental analysis and nitrogen sorption analysis). In addition, eight MOF materials [MIL-101(Cr), ED-g-MIL-101(Cr), TEPA-g-MIL-101(Cr), MIL-101(Cr)-NH2, MIL-101(Al)-NH2, UiO-66(Zr), UiO-66-NH2 and UiO-66(COOH)2] were successfully synthesized. They were chosen due to having high surface areas and large porosity. These MOF compounds were characterized using PXRD, SEM, TGA, and low pressure N2.Successful PIM-1/MOF MMMs were fabricated utilising PIM-1 and the MOFs outlined above with various loadings. The highest MOF loading achieved was 28.6 wt. %, apart from MIL-101(Cr)-NH2, for which it was 23.1 wt. %, and MIL-101(Al)-NH2, for which it was 19.8 wt. %. The morphology of MMMs was characterized by scanning electron microscopy (SEM), proving the dispersion of MOF fillers. Novel PIM-1 supported MOF membranes were successfully prepared by depositing ZIF-8 and HKUST-1 layers on the surfaces of unmodified and modified PIM-1 membranes. These materials were characterized using PXRD, SEM, ATR-IR and SEM-EDX. Gas permeation properties of the MOF/PIM-1 MMMs and PIM-1 supported MOF membranes were determined using a time lag method. Most MMMs tested showed an increase in the permeability and stable selectivity as the MOF amount was increased. However, this was not true for MIL-101(Al)-NH2, where the permeability and selectivity decreased. In contrast, PIM-1 supported ZIF-8 and HKUST-1 membranes caused a sharp decrease in the permeability and increase in the selectivity.