Application of the Gouy-Chapman equation in metal speciation modelling

H. S.T. Driver, H. A. Elliott, P. W. Linder

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

While expanding a speciation model to include adsorption of trace elements in marine aquatic systems, we encountered a confusing presentation of the Gouy-Chapman (G-C) equation which is used to quantify ion sorption on charged particles. The G-C equation relates particle surface charge (σ in C m-2) and surface potential (ψ in V) as: σ = [8×n(o)×ε(r)×ε(o)×kT]1/2 sinh[Zeπ2kT] where n(o) is the concentration of ions (m-3), ε(r) is the dimensionless dielectric constant of the surrounding medium, ε(o) is the permittivity of vacuum, kT is the Boltzmann constant times the absolute temperature, z is the ion valence, and e is the charge of an electron (C). For an aqueous medium of ionic strength I (M) containing uniunivalent electrolytes at 25°C, σ = 0.1174 I1/2 sinh(19.46ψ). The square root argument of the G-C equation has alternatively been reported as [(2/π)×n(o)×ε(r)×kT], making it unclear how the factor of 0.1174 is obtained. We have reconciled these different expressions in order to assist others in applying the G-C equation in speciation models including electrostatic adsorption.

Original languageEnglish (US)
Pages (from-to)61-62
Number of pages2
JournalChemical Speciation and Bioavailability
Volume3
Issue number2
DOIs
StatePublished - Jul 1991

All Science Journal Classification (ASJC) codes

  • Toxicology
  • Chemical Health and Safety
  • Health, Toxicology and Mutagenesis

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