Vapor separation by mixed matrix polymeric membranes


Thesis Type: Doctorate

Institution Of The Thesis: Middle East Technical University, Faculty of Engineering, Department of Chemical Engineering, Turkey

Approval Date: 2018

Thesis Language: English

Student: FATMA ŞAHİN

Principal Supervisor (For Co-Supervisor Theses): Halil Kalıpçılar

Co-Supervisor: Berna Topuz

Abstract:

ZIF-8, ZIF-L, ZIF-7 and ZIF-67 were synthesized from fresh and recycled synthesis solutions. The crystal morphology, N2 adsorption capacity and thermal behavior of ZIFs from recycled solutions were similar to those obtained from the fresh solution. The recycling procedures improved the efficiency of crystallization such that 0.36 g ZIF-7/g organic linker was obtained after two recycling steps, although only 0.16 g ZIF-7/ g organic linker can be obtained after single step synthesis using fresh solution. From an environmental perspective, the developed procedures allowed to consume a great extent of organic linker used for synthesis, therefore the amount of waste organic linker was reduced. A PDMS-based membrane is potentially appropriate for separation of organic solvents from N2. Six different membrane - pure PDMS membrane, ZIF-8/PDMS MMMs, ZIF-L/PDMS MMMs, ZIF-67/PDMS MMMs, ZIF-7/PDMS MMMs and ZIF-71/PDMS MMMs were prepared. Incorporation of ZIF-L enhanced the VOCs permeability and VOC/N2 selectivity by 60 % and 33 % with respect to pure PDMS membrane. Single VOCs/N2 mixtures and multicomponent VOCs/N2 mixtures were tested at different temperatures. It was found that VOCs and N2 showed inverse response with temperature change. Effect of VOCs concentration in the feed stream was determined via decreasing VOCs concentration by 1 % in the feed stream. It was observed that VOCs permeability and α VOCs/N2 decreased % 27 and 40 %, respectively.