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Dissolution Study of Salt of Long Chain Fatty Acids (Soap Scum) in Surfactant Solutions. Part I: Equilibrium Dissolution

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Journal of Surfactants and Detergents

Abstract

Dissolution of calcium salt of a long chain fatty acid or soap scum is a major challenge for hard surface cleaners since soap scum forms when soap is exposed to hard water and has very low water solubility. In this paper, the aqueous equilibrium solubility of calcium octadecanoate (or calcium stearate) was measured as a function of pH as well as chelating agent (ethylenediaminetetraacetate disodium salt) and surfactant concentrations. Anionic, nonionic, and amphoteric surfactants were studied. The highest soap scum solubility was observed at high pH with an amphoteric surfactant. Under this condition, the chelant effectively binds calcium, and the stearate anion forms mixed micelles well with the amphoteric surfactant, which is in zwitterionic form at high pH.

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Acknowledgments

Financial support for this work was provided by the industrial sponsors of the Institute for Applied Surfactant Research at the University of Oklahoma, including Akzo Nobel, Clorox, Conoco/Phillips, Church and Dwight, Dow, Ecolab, Halliburton, Huntsman, Oxiteno, Procter & Gamble, Sasol, SC Johnson, and Shell. Dr. Scamehorn holds the Asahi Glass Chair in the School of Chemical, Biological and Materials Engineering at the University of Oklahoma. Dr. Sabatini holds the Sun Oil Company Chair in the School of Civil Engineering and Environmental Science at the University of Oklahoma.

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Authors and Affiliations

  1. Institute for Applied Surfactant Research, University of Oklahoma, Norman, OK, USA

    Sukhwan Soontravanich, Heyde E. Lopez, John F. Scamehorn & David A. Sabatini

  2. Clorox Technical Center, Pleasanton, CA, USA

    David R. Scheuing

Authors
  1. Sukhwan Soontravanich
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  2. Heyde E. Lopez
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  3. John F. Scamehorn
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  4. David A. Sabatini
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  5. David R. Scheuing
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Correspondence to John F. Scamehorn.

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Soontravanich, S., Lopez, H.E., Scamehorn, J.F. et al. Dissolution Study of Salt of Long Chain Fatty Acids (Soap Scum) in Surfactant Solutions. Part I: Equilibrium Dissolution. J Surfact Deterg 13, 367–372 (2010). https://doi.org/10.1007/s11743-010-1208-5

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  • DOI: https://doi.org/10.1007/s11743-010-1208-5

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