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Titolo:
ADSORPTION OF ALKYLTRIMETHYLAMMONIUM BROMIDES ON SILICA - CALORIMETRIC STUDY OF EFFECT OF COIONS
Autore:
WANGNERUD P; BERLING D; OLOFSSON G;
Indirizzi:
CHEM CTR LUND,DIV THERMOCHEM,POB 124 S-22100 LUND SWEDEN CHEM CTR LUND,DIV THERMOCHEM S-22100 LUND SWEDEN
Titolo Testata:
Journal of colloid and interface science
fascicolo: 2, volume: 169, anno: 1995,
pagine: 365 - 375
SICI:
0021-9797(1995)169:2<365:AOABOS>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
VARIABLE-CHARGE SURFACES; SOLID LIQUID INTERFACES; IONIC SURFACTANTS; CATIONIC SURFACTANTS; THERMODYNAMIC MODEL; ANIONIC SURFACTANTS; AQUEOUS-SOLUTIONS; ADSORBED LAYER; ENTHALPIES; 25-DEGREES-C;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
P. Wangnerud et al., "ADSORPTION OF ALKYLTRIMETHYLAMMONIUM BROMIDES ON SILICA - CALORIMETRIC STUDY OF EFFECT OF COIONS", Journal of colloid and interface science, 169(2), 1995, pp. 365-375

Abstract

Adsorption isotherms and differential enthalpies of adsorption have been determined for dodecyl- and tetradecyltrimethylammonium bromide onsilica at initial pH 9 and on mica in sodium, tetramethylammonium, and calcium bromide solutions of low concentrations. The adsorption isotherms show a clear difference between the influence of the various colons at low coverage and the effect is also seen in the calorimetric results. The initial adsorption is discussed in terms of a competition between surfactant ions and ions of the same charge. The colon effect disappears at higher adsorption densities. The relation between the shape of the adsorption isotherm and the charge properties of the surfaceand their variation with experimental conditions are discussed. The general trend of the change of the differential adsorption enthalpies with coverage is the same for the adsorption on silica and mica except in the initial stage. As the surface coverage increases, there is a steady decrease toward more exothermic values so, as the maximum adsorption is reached, the adsorption enthalpy for tetradecyltrimethylammonium bromide on silica is -10 kJ/mol more exothermic than the enthalpy ofmicelle formation. The change of the adsorption enthalpy with surfacecoverage is discussed in terms of changes in the structure of the aggregates formed at the surface. The calorimetric results are consistentwith the interpretation of the adsorption of surfactants on highly charged surfaces expressed in a newly developed thermodynamic model implying adsorption of small discrete aggregates at the lowest adsorption densities and bilayer formation in the later stages of adsorption. (C)1995 Academic Press, Inc.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/04/20 alle ore 00:14:15