Over the past few decades there has been great interest in exploring alternatives to conventional separation methods due to their high cost and energy requirements. Membranes offer a potentially attractive alternative as they potentially address both of these points. The overarching theme of this dissertation is to design nanocomposite membranes for processes where existing separation schemes are inadequate. This dissertation focuses on three challenges: 1) designing organic-inorganic hybrid membranes for reverse-selective removal of alkanes from light gases, 2) defect-free inorganic nanocomposite membranes that have uniform pores, and 3) nanocomposite membranes for minimizing protein fouling in microfiltration applications.
Reverse-selective gas separations that preferentially permeate larger/heavier molecular species based on their greater solubility have attracted considerable recent attention due to both economic and environmental concerns. In this study, dendrimer-ceramic hybrid membranes showed exceptionally high propane/nitrogen selectivities. This result was ascribed to the presence of stable residual solvent that affects the solubility of hydrocarbon species. Mesoporous silica-ceramic nanocomposite membranes have been fabricated to provide defectless mesoporous membranes. As mesoporous silica is iteratively synthesized in the ceramic macropores, the coating method and the surfactant removal step significantly affected permeance and selectivity. It was also shown that support layers can cause a lower selectivity than Knudsen limit.
Membrane fouling which results from deposition and nonspecific adsorption of proteins on the membrane surface is irreversible in nature, and results in a significant decrease in the membrane performance. To address this problem, two approaches were explored: 1) control of the surface chemistry tethering alumina membranes with organic components and 2) development of a novel photocatalytic membrane that exhibits hydrophilicity and can be easily regenerated. Both approaches can offer a viable route to the synthesis of attractive membranes, in that 1) the density of protein-resistant organic groups such as PEG is controllable by changing scaffolds or synthesis conditions and 2) the photocatalytic nanocomposite membranes can open the way for a new regeneration method that is environmentally benign.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2009-08-7152 |
| Date | 2009 August 1900 |
| Creators | Yeu, Seung Uk |
| Contributors | Shantz, Daniel F. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | application/pdf |
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