Abstract
Suspension of a Tunisian palygorskite is studied by acid-base potentiometer and mass titrations in order to determine the point of zero charge (PZC). The Gran plot method, commonly used to determine the equivalence points, is applied for the hydroxide titration with the purpose to calculate the average number of protons reacted per surface site (Z) and then the surface site density of palygorskite suspension at a given ionic strength. The dissociation coefficients of palygorskite surface are calculated and consequently the surface constants acidities are determined by graphical extrapolation method. The studied samples, performed at different ionic strengths, presented Z vs. pH curves with a common crossing point at pH = 9.8 (pHPZC). For the purpose of eliminating the influence of the palygorskite dissolution and the hydrolysis of soluble ions, the net number of surface reacted protons per surface site (Z net) is determined. Z net vs. pH leads to PZC of 8.8 witch is in agreement with the mass titration results. For illustrating the acidic characteristics of palygorskite surface, two surface protonation models are tested: the one site-one pK a, ≡ SOH ⇆ SO− + H+, pK a 6.2–6.88; and the two sites-two pK as model, ≡SIOH ⇆ ≡SIO− + H+, pK a1 5.26–5.89 and ≡SIIOH ⇆ ≡SIIO− + H+, pK a2 9.15–9.71. Both of them give a good description of the experimental data.
Similar content being viewed by others
References
Neeman, A. and Singer, A. Appl. Clay Sci., 2004, vol. 25, P. 121.
Galan, E., Clay Miner., 1996, vol. 31, p. 443.
Zhuang, J. and Yu, G.R., Chemosphere, 2002, vol. 49, P. 619.
Minerals in the Soil Environments, Dixon, J. and Weed, S., Eds., Madison (WI): SSSA, 1989, 2nd ed.
Itami, K. and Fujitani, H., Colloids Surf. A, 2005, vol. 265, p. 55.
Appel, C., Lena, Q., Dean Rhue, M.R., and Kennely, E., Geoderm., 2003, vol. 113, p. 77.
Hayes, K.F., Redden, G., Ela, W., and Leckie, J.O., J. Colloid Interface Sci., 1991, vol. 142, p. 448.
Schroth, B.K. and Sposito, G., Clays Clay Minerals, 1997, vol. 45, p. 85.
Kriaa, A., Hamdi, N., and Srasra, E., Anal. Chem. Ind. J., 2005, vol. 2, p. 10.
Avena, M. and de Pauli, C.P., J. Colloid Interface Sci., 1998, vol. 202, p. 195.
Noh, S.J. and Schwartz, A.J., J. Colloid Interface Sci., 1989, vol. 130, p. 157.
Neeman, A. and Singer, A., Soil. Sci. Soc. Am. J., 2000, vol. 64, p. 427.
Alkan, M., Demirbas, O., and Dogan, M., J. Colloid Interface Sci., 2005, vol. 281, p. 240.
Gran, G., Analyst, 1952, vol. 77, p. 661.
Solgic, Z. and Marjanovic-Krajovan, Y., Chim. Anal., 1968, vol. 50, p. 122.
Bailey, S.W., in Cristal Structures of Clay Minerals and Their X-Ray Identification, Brindley, G.W. and Brown, G., Eds., London: Mineral Soc., 1980, p. 2.
Du, Q., Sun, Z., Forsling, W., and Tang, H.J., J. Colloid Interface Sci., 1997, vol. 187, p. 221.
Chorover, J. and Sposito, G., Geochim. Cosmochim. Acta, 1995, vol. 59, p. 875.
Citeau, L., Thesis, Paris: Inst. Ntl. d’Agronomie, 2004.
Dove, P.M. and Craven, C.M., Geochim. Cosmochim. Acta, 2005, vol. 69, p. 4963.
Wanner, H., Albinsson, Y., Karnland, O., Wieland, E., Wersin, P., and Charlet, L., Radiochim. Acta, 1994, vol. 66/67, p. 157.
Author information
Authors and Affiliations
Corresponding author
Additional information
Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 7, pp. 834–842.
The text was submitted by the authors in English.
Rights and permissions
About this article
Cite this article
Frini-Srasra, N., Kriaa, A. & Srasra, E. Acid-base properties of Tunisian palygorskite in aqueous medium. Russ J Electrochem 43, 795–802 (2007). https://doi.org/10.1134/S1023193507070099
Received:
Issue Date:
DOI: https://doi.org/10.1134/S1023193507070099