Date of Award

2014

Document Type

Thesis

First Advisor

Lou, Jianzhong

Abstract

Mixed matrix membranes (MMMs) were prepared from Polydimethylsiloxane (PDMS) filled with surface-treated fumed silica (SiO2). Techniques (TGA, SEM, and FTIR) were employed to characterize the neat membrane (PDMS) and the mixed matrix SiO2-PDMS membrane (SiO2-PDMS). The results confirmed SiO2-PDMS has improved thermal property over neat PDMS. Uniform dispersion of SiO2 within the membrane was observed. Good material interaction between PDMS and fumed SiO2 was observed. The effects of SiO2 on the transport pattern and permeability of O2, N2, CO2, and CH4 were studied. Results showed that the presence of SiO2 in PDMS matrix had a significant impact on N2 transport pattern. The incorporation of SiO2 into polymer matrix gave rise to an increase in solubility dominant flux and a corresponding decrease in the diffusivity of the gases through the MMMs as evident in the permeability trend of: PCO2 > PCH4 > PO2 > PN2. 10% SiO2-PDMS maintained stability under continuous and repeated exposure to oxygen. 10% SiO2-PDMS exhibited both improved O2 permeability of about 640 Barrer and O2/N2 selectivity of 3.42 against neat PDMS with O2 permeability of about 520 Barrer and O2/N2 selectivity for O2 over N2 of 2.59. However, neat PDMS had a fair performance for the separation of CO2/CH4 gas pair with CO2 permeability of about 3239 Barrer and selectivity of 4.16 against 10% SiO2-PDMS with 2967 Barrer and selectivity 4.29. This confirmed that SiO2 as nano filler in PDMS is not a suitable material for separation of CO2/CH4 gas pair but could be suitable for the separation of CO2/N2 gas pair.

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