Krafft point
The Krafft point is a narrow temperature range ( Krafft temperature ) above which the solubility of anionic and cationic surfactants increases sharply as a result of the formation of micelles (micelle formation). It is a triple point at which the surfactants exist as monomers , micelles, and as hydrated solids. It is named after Friedrich Krafft , who developed the emulsion theory.
The Krafft point is determined by measuring the turbidity in accordance with DIN 53918. In the case of soaps , the Krafft point is the temperature at which a hot, transparent soap solution becomes cloudy on cooling.
Since there is a weak dependency on the total surfactant concentration in the system, it is also referred to as the Krafft boundary .
literature
- F. Krafft, A. Stern: About the behavior of fatty acid alkalis and soaps in the presence of water. Part I and II in: Ber. German chem. Ges. 27, Volume 4, 1894, pp. 1747–1761, Part III: The soap as crystalloids. 28, Volume 3, 1895, pp. 2566-2573, Part IV: The soap as colloids. 28, Vol. 3, 1895, pp. 2573-2582.
- F. Krafft, A. Strutz: About the behavior of soap-like substances against water. In: Ber. German chem. Ges. 29, Vol. 2, 1896, pp. 1328-1334.
- F. Krafft: About a theory of colloidal solutions. In: Ber. German chem Ges. 29, Vol. 2, 1896, pp. 1334-1344.
- F. Krafft, R. Funke: About the action of water on heptylamine soaps. In: Ber. German chem. Ges. 33, Volume 3, 1900, pp. 3210-3212.
- Amelie Sabine Zapf: Investigations into the behavior of highly swollen lyotropic phases with calcium, magnesium and sodium dodecyl sulfate. Dissertation, 2008 (PDF file; 5.29 MB).
Web links
- Entry to Krafft point . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.K03415 Version: 2.3.3.
- Eiper, Frankowski, Opielka, Welzel: Oil paint surface cleaning, p. 24.
Individual proof
- ↑ H.-J. Butt, K. Graf, M. Kappl: Physics and chemistry of interfaces . Wiley-VCH, 2003, ISBN 9783527404131 .