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Abstract

The results of thermodynamic analysis of o-toluidine adsorption on a mercury electrode in the presence of various butan-1-ol amounts complete our previous studies on properties of mixed adsorption layers of toluidine isomers-butan-1-ol. The values of the relative surface excess Γ'_°T obtained for o-toluidine show that adsorption of this compound decreases with increasing of butan-1-ol concentration. Analysis of adsorption parameters derived from the Frumkin isotherm indicates that in the presence of 0.33 M BuOH in 1 M NaClO₄ with adjusted pH 3 as supporting electrolyte, ∆G⁰ values for o-toluidine are the highest and, at the same time, the strongest repulsive interaction occurs. In the presence of 0.11 M butan-1-ol, smaller values of ∆G⁰ for o-toluidine correspond to weaker repulsive interaction. Therefore the change of the Γ'_°T value for o-toluidine as a function of butan-1-ol concentration is the result of mutual changes of ∆G⁰ and interaction constant A between adsorbate molecules.

Keywords: Adsorption isotherm; Surface pressure; Surface charge density; Thermodynamics; Alcohols; Butanol; Toluidine.

References: 14 live references.