Synthesis of Mixed Matrix Membranes for Energy and Environmental Applications

Abstract

The production of renewable fuels have received great attention due to the problematic effects of non-renewable fuels on environment. Ethanol purification is very essential for obtaining fuel grade ethanol but the conventional processes to convert bio mass to bio fuel is very high energy intensive and costly process. Concentration of ethanol during fermentation process generally ranges up to 1-15% depending upon the source of bio mass. The water contents should be reduced to 1-3 wt% for obtaining fuel grade ethanol. Distillation is commonly adopted technique for the separation of ethanol from fermentation broths. However, this technique is very high energy intensive hence opening the doors of some other techniques such as gas stripping, adsorption etc. Another technique which is used to separate water/alcohol mixture is via hydrophobic pervaporation. Pervaporation is a membrane based separation process in which feed is entered in the form of liquid and vapors are obtained as permeate. Polymeric membrane and inorganic membranes are not widely accepted due to tradeoff relationship between flux and selectivity. This thesis mainly focused on the synthesis of Zeolitic Imidazole Framework (ZIF) based Mixed Matrix Membrane (MMM) to increase the separation performance of ethanol/water mixture. Polydimethylsiloxane (PDMS) is an elastomer which is widely used for hydrophobic pervaporation due to its high selectivity, chemical stability and high hydrophobic nature. During the course of this thesis, ZIF-67; a hydrophobic filler was selected and synthesized due to its high chemical and thermal stability and high hydrophobic nature. ZIF-67/PDMS membranes were synthesized using polyimide (PI) as a support. Different characterization techniques were adopted to confirm the purity and performance of fillers and membranes. Membranes were tested on home based pervaporation unit to check the performance parameters of pervaporation.