- Title
- Interpretation of negative values of the interaction parameter in the adsorption equation through the effects of surface layer heterogeneity
- Creator
- Karakashev, Stoyan; Manev, Emil; Nguyen, Anh
- Relation
- Advances in Colloid and Interface Science Vol. 112, Issue 1-3, p. 31-36
- Publisher Link
- http://dx.doi.org/10.1016/j.cis.2004.06.002
- Publisher
- Elsevier BV
- Resource Type
- journal article
- Date
- 2004
- Description
- For this purpose, the adsorption states of a homologue series of ethoxylated nonionic surfactants on air/water interface have been determined using four different models and literature data (surface tension isotherms). The results obtained with the Frumkin adsorption isotherm imply repulsion between the adsorbed species (corresponding to negative values of the interaction parameter), while the classical lattice theory for energetically homogeneous surface (e.g., water/air) admits attraction alone. It appears that this serious contradiction can be overcome by assuming heterogeneity in the adsorption layer, that is, effects of partial condensation (formation of aggregates) on the surface. Such a phenomenon is suggested in the Fainerman–Lucassen–Reynders–Miller (FLM) 'Aggregation model'. Despite the limitations of the latter model (e.g., monodispersity of the aggregates), we have been able to estimate the sign and the order of magnitude of Frumkin's interaction parameter and the range of the aggregation numbers of the surface species.
- Subject
- adsorption; interactions; surface heterogeneity; aggregation
- Identifier
- http://hdl.handle.net/1959.13/33951
- Identifier
- uon:3408
- Identifier
- ISSN:0001-8686
- Language
- eng
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