Polymer Supported ZIF Membrane For Molecular Separation

Zeolitic imidazole frameworks are porous open crystalline materials consisting of metals units(such as Zn,Co)and organic linkers.Where the M-Im-M angle in ZIFs are similar to Si-O-Si angle(145°)which led to the synthesis of a large number of ZIFs with zeolite-type tetrahedral topologies.Because of their porous nature and tunable structure,ZIFs material has been widely used in many fields such as gas separation,gas storage,catalysis,chemical sensor and absorption of different pollutants from water.For effective application,it is important to fabricate zeolitic imidazole framework into membrane materials.Since ZIF membrane materials show superior capability of molecular discrimination,they are highly suggested for practical implementable for industrial application.However,ZIFs membranes are largely limited because of its poor interaction with substrate,less continuity among crystals and high cost in membrane fabrication.The purpose of my thesis is based on fabrication Zeolitic imidazole framework membranes,its effective growth with substrate modification and without substrate modification,and its application in gas separation and absorption of pollutants.Hence,the related literature have been introduced on the synthesis of ZIF membrane,different approaches of membrane fabrication on different modified substrate and its application in different fields in Chapter 1.ZIF-8 and ZIF-67 two types of zeolitic imidazole framework are fabricated on the LDH coated PAN-PVDF mixed polymer fibers with a facile and effective method in Chapter2.The LDHs(ZnAl-LDH and CoAl-LDH)have been coated on Boehmite(AlOOH)containing Electrospun polymer fibers through in situ hydrothermal method.The direct electrospining of Boehmite(AIOOH)in PAN?PVDF nanofibers facilitate the LDH growth on fibers and avoiding Sol-gel coating method which is long process of Aluminum precursor adding.The ZIF fabricated on LDH coated polymer fibers with high continuity and with control temperature constitutes a new multilayer structure.The as-prepared Polymer-LDH-ZIF membrane can be used to separate H2 from other gases as CH4/H2,N2/H2 and CO2/H2.Both ZIFs membrane show better separation performance for H2 separation,the selectivity of ZIF-67 for CH4/H2 is 12.8 much better than that of ZIF-8 which is 7.6.The theoretical studies and our investigation indicateZIF-67 have less fragile structure and narrow pore size compared with ZIF-8.Chapter 3 describes multilayer exfoliated ZIF-8 arranged in microvilli-like morphology in human intestine that has been fabricated on Electrospun polymer substrate.The fabrication of MOF is controlled through slow nucleation of organic linkers which provide a new shape to ZIF-8.This new shape of ZIF-8 highly resembles with humane intestine microvilli structures.This special ZIF-8 structure is supported on Polymers fibers in order to provide a functional shape.Polymer nanofibers sheet was immersed directly in ZIF precursor solution to grow uniform and thick layer of ZIF-8 on polymer support.The thickness of ZIF-8 was monitored with time interval(Increase the time interval can increase the thickness).The ZIF-polymer membrane is converted into a column shape by folding it in order to expose the internal surface for effective absorption of dyes.The dyes solution was passed through the ZIF-8-polymer column,the ZIF layer column absorb the dye with high efficiency and high permeability.The inter layer gapes provide high absorption sites for absorption.The dyes solution was also passed through normal ZIF-8 membrane which can absorb enough dye from the solution but the efficiency is lower than exfoliated shape ZIF.Our strategy demonstrate that the Shape change of ZIF-8 improve the absorption capacity.