Prediction of solubility of nonpolar gases in micellar solutions of ionic surfactants
DSpace at IIT Bombay
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Title |
Prediction of solubility of nonpolar gases in micellar solutions of ionic surfactants
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Creator |
ROY, S
MEHRA, A BHOWMICK, D |
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Subject |
thermodynamics
association interfaces systems phase micellar solubilization nonpolar gases ionic surfactants |
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Description |
The solubilities of methane, carbon dioxide, ethane, and propane have been determined experimentally at 1 atm partial pressure and 25 degrees C in aqueous solutions of sodium dodecyl sulfate and cetyltrimethylammonium bromide. For this purpose a specially developed apparatus is used, which is relatively simple compared to those reported in the literature hitherto. Above the CMC, the solubility of each gas increases linearly with surfactant concentration indicating micellar solubilization. The degree of solubilization is greatest for propane and decreases in the order propane > ethane > carbon dioxide > methane. Both the length of the alkyl chain and the properties of the head-group region (i.e., the micelle-water interfacial tension) are observed to determine the intramicellar solubility. A method for estimating the solubilities is also proposed based on the rationale that the micellar phase may be represented by a droplet of a "model solvent" into which the solubilizate molecule dissolves as it would in a bulk solvent. The mixture of the solute species and the model solvent is assumed to behave as a regular solution. Accordingly, a characteristic solubility parameter is estimated for the model solvent from the interaction potential between two adjacent surfactant molecules in a micelle. The solubility computed using the regular solution approximation is further corrected for the Laplace pressure that acts across the curved micelle-water interface and generally reduces the intramicellar solubility. It is concluded that for small nonpolar solutes, micellar solubilities may be reasonably well predicted by assuming that the model solvent has a solubilizing capacity (i.e., solubility parameter) close to that of a bulk equivalent alkane. (C) 1997
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Publisher |
ACADEMIC PRESS INC
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Date |
2011-07-12T12:54:35Z
2011-12-26T12:48:54Z 2011-12-27T05:34:24Z 2011-07-12T12:54:35Z 2011-12-26T12:48:54Z 2011-12-27T05:34:24Z 1997 |
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Type |
Article
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Identifier |
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 196(1), 53-61
0021-9797 http://dx.doi.org/10.1006/jcis.1997.5181 http://dspace.library.iitb.ac.in/xmlui/handle/10054/3330 http://hdl.handle.net/10054/3330 |
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Language |
en
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