Solubility-based membrane separation, in which the more soluble species
preferentially permeates across the membrane, has attracted considerable recent attention
due to both economic and environmental concerns. This solubility-selective mode is
particularly attractive over a diffusivity-selective mode in applications in which the
heavier species are present in dilute concentrations. Examples include the recovery of
volatile organic components (VOCs) from effluent streams and the removal of higher
hydrocarbons from natural gas. Recently, nanocomposites have shown great promise as
possible membrane materials for solubility-selective separations. The chemical
derivatization of inorganic mesoporous substrates has been explored to synthesize
organic-inorganic nanocomposite membranes. The most exciting feature of this
approach is that it enables the rational engineering of membrane nano-architecture with
independent control over the free volume and chemistry to create membranes with
highly customizable permselectivity properties. In this study, we synthesized the organic-inorganic nanocomposite membranes
by decorating the surfaces of commercially available mesoporous alumina substrates,
and surfactant-templated highly ordered mesoporous silicate thin films placed on
commercially available macroporous inorganic substrates, with a selective organic
material that is physically or chemically anchored to the porous surfaces.
Hyperbranched melamine-based dendrimers, with nanometer dimension and chemical
composition designed to target certain components, were used as filling agents. We
evaluated these membranes for several environmentally relevant separations, such as the
recovery of the higher hydrocarbon from air and the removal of trace VOCs from air or
water, while exploring the impact of organic oligomer size, chemistry, and surface
coverage, as well as substrate pore size and structure, on membrane performance. First,
we did a model study to verify the feasibility of dendrimer growth inside mesopores by
using ordered mesoporous silica. Alumina-ordered mesoporous silica (alumina-OMS)
hybrid membranes were prepared as new inorganic porous substrates. Finally, we
synthesized dendrimer-ceramic nanocomposite membranes by growing several
generations of melamine-based dendrimers with diverse functional groups directly off
the commercial alumina membranes. Composite membranes show very high
propane/nitrogen selectivity up to 70.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1070 |
| Date | 15 May 2009 |
| Creators | Yoo, Suk Joon |
| Contributors | Ford, David M., Shantz, Daniel F. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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