Titration of fatty acids solubilized in cationic and anionic micelles. Calorimetry and thermodynamic modeling
(2006) In The Journal of Physical Chemistry Part B 110(7). p.3288-3293- Abstract
- The electrostatic properties of charged surfactant micelles are investigated through titrations of fatty acid probes solubilized in the micelles. The titration process is followed by means of calorimetric measurements and by determining the pH values as a function of added base. This approach yields a complete thermodynamic description of the titration process. In particular, we find that the process is endothermic at 298 K. This is contrary to the titration of carboxylic acids in water, where Delta H is approximately 0. To identify the main effect underlying the difference in Delta H between titration in a micelle and water, a thermodynamic model has been developed which focuses on the transfer properties of charged and uncharged species... (More)
- The electrostatic properties of charged surfactant micelles are investigated through titrations of fatty acid probes solubilized in the micelles. The titration process is followed by means of calorimetric measurements and by determining the pH values as a function of added base. This approach yields a complete thermodynamic description of the titration process. In particular, we find that the process is endothermic at 298 K. This is contrary to the titration of carboxylic acids in water, where Delta H is approximately 0. To identify the main effect underlying the difference in Delta H between titration in a micelle and water, a thermodynamic model has been developed which focuses on the transfer properties of charged and uncharged species from bulk water to the surface of a micelle and which incorporates a dielectric discontinuity at the micellar surface. The model relies on the use of the Poisson-Boltzmann equation which is solved using a finite element method. Experimental results and the model calculations imply that the dielectric discontinuity at (or near) the micellar surface plays a major role and hence must be included when analyzing the titration behavior of an acid functionality at the surface of a charged micelle. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/417091
- author
- Söderman, Olle LU ; Jönsson, Bengt LU and Olofsson, Gerd LU
- organization
- publishing date
- 2006
- type
- Contribution to journal
- publication status
- published
- subject
- in
- The Journal of Physical Chemistry Part B
- volume
- 110
- issue
- 7
- pages
- 3288 - 3293
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- wos:000235560900050
- scopus:33644921493
- ISSN
- 1520-5207
- DOI
- 10.1021/jp056861h
- language
- English
- LU publication?
- yes
- id
- ccbf5d2e-44ae-49f8-94d0-18eb4f9eea72 (old id 417091)
- date added to LUP
- 2016-04-01 16:51:27
- date last changed
- 2022-01-28 22:39:26
@article{ccbf5d2e-44ae-49f8-94d0-18eb4f9eea72,
abstract = {{The electrostatic properties of charged surfactant micelles are investigated through titrations of fatty acid probes solubilized in the micelles. The titration process is followed by means of calorimetric measurements and by determining the pH values as a function of added base. This approach yields a complete thermodynamic description of the titration process. In particular, we find that the process is endothermic at 298 K. This is contrary to the titration of carboxylic acids in water, where Delta H is approximately 0. To identify the main effect underlying the difference in Delta H between titration in a micelle and water, a thermodynamic model has been developed which focuses on the transfer properties of charged and uncharged species from bulk water to the surface of a micelle and which incorporates a dielectric discontinuity at the micellar surface. The model relies on the use of the Poisson-Boltzmann equation which is solved using a finite element method. Experimental results and the model calculations imply that the dielectric discontinuity at (or near) the micellar surface plays a major role and hence must be included when analyzing the titration behavior of an acid functionality at the surface of a charged micelle.}},
author = {{Söderman, Olle and Jönsson, Bengt and Olofsson, Gerd}},
issn = {{1520-5207}},
language = {{eng}},
number = {{7}},
pages = {{3288--3293}},
publisher = {{The American Chemical Society (ACS)}},
series = {{The Journal of Physical Chemistry Part B}},
title = {{Titration of fatty acids solubilized in cationic and anionic micelles. Calorimetry and thermodynamic modeling}},
url = {{http://dx.doi.org/10.1021/jp056861h}},
doi = {{10.1021/jp056861h}},
volume = {{110}},
year = {{2006}},
}