Preparation of hollow fibers for the removal of volatile organic compounds from air

Abstract

Hollow-fiber membranes were prepared to remove volatile organic vapors (VOCs) from a nitrogen or air stream. Conditions were found to spin hollow fibers of high performance for the removal of VOCs. The effect of temperature on the permeation of nitrogen gas and acetone vapor was studied. It was found that nitrogen permeation was governed by diffusion while vapor permeation was governed by sorption. There were two distinct mechanisms for vapor permeation, depending on temperature. Performance data for hollow fibers with and without a silicone rubber coating at the internal surface were compared. The effect of the presence of water vapor in the feed was also studied.

Membrane-Mediated Extraction and Biodegradation of Volatile Organic Compounds From Air

“…The separation factor can also be written in terms of the permeabilities of the two penetrants and the relative partial pressure driving forces (Ashworth, 1992;Koros, 1993;Stern, 1994): Written in this manner, the separation factor can be seen to have contributions derived from penetrant solubility (S A /S B ) and penetrant mobility (D A /D B ). Selective solubility is the controlling factor in processes involving the separation of vapors from gases, such as VOC removal from air (Baker, 1987;Watson, 1990;Lund, 1996;Deng, 1998). The motion of polymer segments in the membrane controls mobility selectivity.…”

“…This is due to the strongly exothermic nature of absorption of organic vapors into PDMS (Leemann, 1996). Similar temperature dependence was noted for pervaporation of carbon dioxide and methane through polypropylene and PDMS membranes coated with fluoropolymer films (Oh, 1996), acetone and ethanol permeation through microporous glass (Qiu, 1991), and acetone pervaporation through silicone rubber (Deng, 1998) Penetrant concentration, as indicated by the partial pressure of the penetrant in the vapor phase, has a greater effect upon permeability through PDMS at lower temperatures (below 50 °C). At low feed-gas temperatures, permeability increases with penetrant partial pressure, presumably due to increasing diffusivity due to polymer swelling (Leemann, 1996).…”

Separation of gasoline vapor from nitrogen by hollow fiber composite membranes for VOC emission control

“…There have been some efforts to modify silicone polymers by fluorination and cross-linking so as to improve the chemical resistance of the membranes for VOC separation [11]. Other attempts have also been made to explore the possibility of using microporous polyimide and polyetherimide membranes without coating to separate organic vapors from air or nitrogen [12][13][14][15]; presumably, the membrane permselectivity is due to surface diffusion of VOC molecules sorbed on the wall of the membrane pores.…”

Development of thin-film composite hollow-fiber membranes from modified polyphenylene oxide for gas separation applications

“…In the first case, a 22.5 wt % solution of PEI in dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP), containing 1.0 -1.5 wt % of lithium nitrate was used following the method similar to that described by Deng and others. 13 In the second case, a spinning procedure described by Kneifel and Peinemann 14 was adopted.…”