Original scientific paper

Interactions of Sodium Dodecylbenzenesulfonate and Calcite in 0.55 M NaCl Solution

Damir Krznarić ; Ruđer Bošković Institute, Center for Marine Research, P.O.B. 1016, 10001 Zagreb, Croatia
Nada Filipović-Vinceković ; Ruđer Bošković Institute, Department of Chemistry, P.O.B. 1016, 10001 Zagreb, Croatia
Vesna Babić-Ivančić ; Ruđer Bošković Institute, Department of Chemistry, P.O.B. 1016, 10001 Zagreb, Croatia
Halka Bilinski ; Ruđer Bošković Institute, Department of Chemistry, P.O.B. 1016, 10001 Zagreb, Croatia

Abstract

Complex mutual interactions of calcite and sodium dodecylbenzene sulfonate (NaDBS) were studied in 0.55 M NaCl solution, using several complementary techniques.
Adsorption of NaDBS on calcite could be resolved from other processes such as adsorption onto the reaction vessel and/or formation of solid crystalline phase, when a special a.c. voltammetric procedure was used below the critical micelle concentration (c.m.c. = = 9 x 10-5 mol/L). A two-plateau type isotherm was obtained. Initial adsorption of NaDBS occurs at Ca2+ ions on the calcite/solution interface through electrostatic interactions. The second stage of adsorption was described as hydrophobic interaction between hydrocarbon chains from bulk solution and those electrostatically adsorbed on calcite, forming surface aggregates.
The results of adsorption were analyzed by a two-step adsorption model. The equilibrium constants and &2 for the first and second adsorption step, the surface aggregation number, re, the amount of adsorbed monomer, the saturated adsorption, rm and the standard free energy of surface aggregate formation for one mole of surfactant, AG^m, were calculated.

Keywords

Hrčak ID:

135607

URI

https://hrcak.srce.hr/135607

Publication date:

3.4.1997.

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