Lorne, Benoit and Perrier, Frédéric and Avouac, Jean-Philippe (1999) Streaming potential measurements 1. Properties of the electrical double layer from crushed rock samples. Journal of Geophysical Research B, 104 (B8). pp. 857-877. ISSN 0148-0227. http://resolver.caltech.edu/CaltechAUTHORS:20120910-104113980
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The ξ potential has been inferred from streaming potential measurements with crushed rock samples as a function of pH and electrolyte concentration for various salts. The value obtained for crushed Fontainebleau sandstone at pH = 5.7 and a KCl solution with a resistivity of 400 Ω m is −40 ± 5 mV, where the error is dominated by sample to sample variations. The sensitivity of the ξ potential to the electrolyte resistivity for KCl is given experimentally by ρ_f^(0.23±0.014) where ρ_f is the electrolyte resistivity. The point of zero charge (pzc) is observed for pH = 2.5 ± 0.1, and the ξ potential is positive for pH < pzc and negative for pH > pzc. For pH > 5 the variations of the ξ potential with pH can be approximated by ξ(pH)/ξ(5.7) = 1 + (0.068 ± 0.004)(pH - 5.7) for ρ_f = 100 Ω m. The ξ potential has been observed to be sensitive to the valence of the ions and is approximately reduced by the charge of the cation, unless specific adsorption takes place like in the case of Al^3+. The experimental results are well accounted for by a three-layer numerical model of the electrical double layer, and the parameters of this model can be evaluated from the experimental data. The sensitivity of the ξ potential to the rock minerals has also been studied. The ξ potential obtained for granitic rocks is comparable to that obtained for Fontainebleau sandstone but can be reduced by a factor of 2–4 for sandstones containing significant fractions of carbonates or clay. To take into account the effect of the chemical composition of the electrolyte, a chemical efficiency is defined as the ratio of the ξ potential to the ξ potential measured for KCl. This chemical efficiency is measured to be ∼80% for typical groundwater but can be as low as 40% for a water with a high dissolved carbonate content. The set of empirical laws derived from our measurements can be used to assess the magnitude of the streaming potentials expected in natural geophysical systems.
|Additional Information:||© 1999 American Geophysical Union. Received 3 April 1998; accepted 20 April 1999; published 10 August 1999. The authors are grateful to the Laboratoire de Détection et de Géophysique for financial and technical support. Funds were also received from the French Ministry of Environment. Most of the experiments were performed with the help of Thierry Froidefond and Pierre Lalance. In addition, Jean Aupiais and his team of chemists helped with advise, equipment, measurements, and analysis of the electrolytes. Patrick Dupont is thanked for the fabrication of many pieces of the apparatus. The authors also acknowledge enlightening exchanges with Laurence Jouniaux, Jean-Pierre Pozzi, Paul Glover, and André Revil and especially thank Steve Pride for introducing them to the work of Davis et al. ). M. Johnston and B. J. Wanamaker are thanked for their detailed and constructive review.|
|Official Citation:||Lorne, B., F. Perrier, and J.-P. Avouac (1999), Streaming potential measurements 1. Properties of the electrical double layer from crushed rock samples, J. Geophys. Res., 104(B8), 17,857–17,877, doi:10.1029/1999JB900156.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||12 Sep 2012 17:57|
|Last Modified:||26 Dec 2012 16:08|
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