Calorimetric study of the adsorption of short-chain nonionic surfactants on silica glass and graphite: Dimethyldecylamine oxide and octyl monoglucoside

Z. Király, G. H. Findenegg

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

The material and enthalpy balances of adsorption of the nonionic surfactants N,N-dimethyldecylamine-N-oxide (C10DAO) and n-octyl β-D-monoglucoside (C8G1) from dilute aqueous solutions onto hydrophilic silica glass and hydrophobic graphite (graphitized carbon black) were determined at 298.15 K up to the critical micelle concentration. An automated flow sorption/microcalorimeter system was used for simultaneous measurements of the adsorption isotherm and the enthalpy isotherm of displacement. The formation of the adsorption layer is discussed in terms of the differential molar enthalpy data of adsorption as a function of surface coverage, and the results are related to the aggregated structure of nonionic surfactants at silica/solution and graphite/solution interfaces studied by atomic force microscopy. On silica, a low-density adsorption region (exothermic) is followed by a high-density adsorption region to produce globular surface aggregates of both C8G1 and C10DAO. On graphite, the formation of a flat, ordered monolayer (exothermic) is followed by the formation of C8G1 surface hemicylinders or, probably, a flat, less ordered bilayer of C10DAO. In either case, the adsorption in the high-density adsorbate region is endothermic, like micelle formation in aqueous bulk solution, as is to be expected on the basis of current models of surface aggregation of nonionic surfactants on hydrophilic and hydrophobic surfaces.

Original languageEnglish
Pages (from-to)8842-8849
Number of pages8
JournalLangmuir
Volume16
Issue number23
DOIs
Publication statusPublished - Nov 1 2000

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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