Functionalized Single Walled Carbon Nanotube/Polymer Nanocomposite Membranes for Gas Separation and Desalination

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dc.contributor.authorSurapathi, Anil Kumaren
dc.contributor.committeechairMarand, Evaen
dc.contributor.committeememberDavis, Richey M.en
dc.contributor.committeememberJohnson, Karlen
dc.contributor.committeememberMartin, Stephen M.en
dc.contributor.departmentChemical Engineeringen
dc.date.accessioned2014-03-14T21:23:02Zen
dc.date.adate2012-11-16en
dc.date.available2014-03-14T21:23:02Zen
dc.date.issued2012-10-26en
dc.date.rdate2012-11-16en
dc.date.sdate2012-11-08en
dc.description.abstractPolymeric membranes for gas separation are limited in their performance by a trade-off between permeability and selectivity. New methods of design are necessary in making membranes, which can show both high permeability and selectivity. A mixed matrix membrane is one such particular design, which brings in the superior gas separation performance of inorganic membranes together with the easy processability and price of the polymers. In a mixed matrix membrane, the inorganic phase is dispersed in the polymeric continuous phase. Nanocomposite membranes have a more sophisticated design with a thin separation layer on top of a porous support. The objective of this research was to fabricate thin SWNT nanocomposite membranes for gas separation, which have both high permeability and selectivity. SWNT/polyacrylic nanocomposite membranes were fabricated by orienting the SWNTs by high vacuum filtration. The orientation of SWNTs on top of the porous support was sealed by UV polymerization. For making these membranes, the CNTs were purified and cut into small open tubes simultaneously functionalizing them with COOH groups. Gas sorption of CO2 in COOH functionalized SWNTs was lower than in purified SWNTs. Permeabilities in etched membrane were higher than Knudsen permeabilities by a factor of 8, and selectivities were similar to Knudsen selectivities. In order to increase the selectivities, SWNTs were functionalized with zwitterionic functional groups. Gas sorption in zwitterion functionalized SWNTs was very low compared to in COOH functionalized SWNTs. This result showed that the zwitterionic functional groups are kinetically blocking the gas molecules from entering the pore of the CNT. SWNT/polyamide nanocomposite membranes were fabricated using the zwitterion functionalized SWNTs by interfacial polymerization. The thickness of the separation layer was around 500nm. Gas permeabilities in the CNT membranes increased with increasing weight percentage of the SWNTs. Gas permeabilities were higher in COOH SWNT membrane than in zwitterion SWNT membrane. Gas selectivities were similar to the Knudsen selectivities, and also to the intrinsic selectivities in the pure polyamide membrane. The water flux in SWNT-polyamide membranes increased with increasing weight percentage of zwitterion functionalized SWNTs, along with a slight increase in the salt rejection. Membranes exhibited less than 1% variability in its performance over three days.en
dc.description.degreePh. D.en
dc.identifier.otheretd-11082012-113518en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-11082012-113518/en
dc.identifier.urihttp://hdl.handle.net/10919/40297en
dc.publisherVirginia Techen
dc.relation.haspartSurapathi_AK_D_2012.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectPlasma Etchingen
dc.subjectFunctionalizationen
dc.subjectGas Permeationen
dc.subjectGas Adsorptionen
dc.subjectDesalinationen
dc.subjectCarbon Nanotubeen
dc.subjectPoly(acrylates)en
dc.subjectPolyamideen
dc.subjectNanocomposite membraneen
dc.titleFunctionalized Single Walled Carbon Nanotube/Polymer Nanocomposite Membranes for Gas Separation and Desalinationen
dc.typeDissertationen
thesis.degree.disciplineChemical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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