Zeolite Imidazole Framework (ZIF)-based Membranes For Pervaporation Applications

ZIF, as one of the most potential porous crystalline material, has many advantages including high porosity, high surface area, good stability, strong adsorption capacity, and etc. ZIF material has therefore received wide attentions in the fields of catalysis,separation and energy storage. Because of its tunable structure and favorable affinity with the polymer matrix, it has a great potencial for applications in pervaporation membranes as compared with most other traditional inorganic particles of rigid frameworks. The purpose of this thesis is to explore the applications of ZIF materials in pervaporation membranes and to optimize the membrane performance to solve existing issues of ZIF-based membrane.Firstly, ethanediamine(EDA)-modified zeolitic imidazolate framework(ZIF)-8particles(ZIF-8-NH2) is synthesized and incorporated in the polyvinylalcohol(PVA)matrix to fabricate novel PVA/ZIF-8-NH2 mixed matrix membranes for pervaporation dehydration of ethanol. The PVA/ZIF-8-NH2 mixed matrix membranes exhibit enhanced membrane homogeneity and separation performance because of the higher hydrophilicity and restricted agglomeration of the particles, as compared to corresponding mixed matrix membranes loaded with unmodified particles. The effect of ZIF-8-NH2 loading in the mixed matrix membranes is studied and the mixed matrix membrane with a 7.5 wt%ZIF-8-NH2 loading shows the best pervaporation performance for ethanol dehydration at40 o C. Various characterization techniques are employed to investigate the mixed matrix membranes loaded with ZIF-8 and ZIF-8-NH2 particles. The impact of operation conditions on pervaporation performance is also carried out. The performance benchmarking shows that the mixed matrix membranes have superior separation factors and comparable flux to most other PVA hybrid membranes.In additions, ZIF-90 nanoparticles were also synthesized and modified with dodecylamine(DLA) by imine condensation reaction in order to improve the particle hydrophobicity and its compatibility with the PDMS matrix. The pervaporation performance of pristine PDMS membrane and novel PDMS/DLA-ZIF-90 mixed matrix membrane are investigated. Various characterizations are also performed to examine theirmorphology and fundamental properties.On the basis of the above works, a new ZIF seeding approach for the synthesis of ZIF-8 continuous layer on polymer substrate was employed in this work. A novel seeding method is employed to cover a high-quality seeding layer on the substrate surface,polyimide substrate membrane is firstly modified by ethylenediamine(EDA) and then soaked in imidazole-2-carboxaldehyde(ICA) solution to induce the reaction between ICA and EDA-modified polyimide. Due to the ICA modification, the new seeding method offers a special advantage of high mechanical stability and excellent ZIF crystal structure as compared with other seeding methods. The as-fabricated ZIF-8/polyimide composite membranes show uniform morphology, excellent IPA/water separation performance, and exceptional mechanical strength. The novel ZIF seeding method can be potentially expanded to other composite membranes with ZIF continuous layer.