On mixed surfactant systems
Investigations were carried out with the intention to establish conditions at which it is possible to prepare two cationic + anionic surfactant systems with the predetermined characteristics. For this purpose, the first colloid system examined was n-dodecylamine nitrate with sodium n-dodecylsulfate, and as the second one negative silver iodide sol with n-dodecylamine nitrate. Each system was prepared separately as a positively, negatively or zero-charged colloid, and then put in contact with the second prepared system. Methylene blue B was also applied as a cationic surfactant. The results direct us to very interesting mutual interactions, very sensitive on associate structure present. Because of high colloid sensitivity on associate structures, very minute determinations of critical concentrations for associate formations were carried out. The results indicate a specific phenomenon which appears as a formation of small maxima on the curve surface tension vs surfactant concentrations. The model of a possible mechanism causing the observed phenomena is explained by a transition dilution, the consequence of which is the surface tension increase in a narrow surfactant concentration at which the associate transforms into a new higher ordered structure.
Key wordsColloids electrophoretic mobility surface tension surfactant
Unable to display preview. Download preview PDF.
- 1.Despotović R, Despotović LA, Fraj B, Salaj-Obelić I (1990) In: Tensioactivos y A (ed) Asociacion de Investigacion de Detergentes; Comunicaciones presentadas a las XXI Jornadas del Comite Espanol de la Detergencia. Barcelona, pp 327–338Google Scholar
- 2.Salaj-Obelić I, Despotović R (1989) In: Proc 7th Yugoslav Symposium on Surface Active Agents, Vol II, pp 457–465Google Scholar
- 3.Salaj-Obelić I, Ph D Thesis, in preparationGoogle Scholar
- 6.Caelles J, Comelles F, Parra IL, Sanchez J, Angeura S (1990) In: Tensioactivos y A (ed) Asociacion de Investigacion de Detergentes; Comunicaciones presentadas a las XXI Jornadas del Comite Espanol de la Detergencia. Barcelona, pp 113–130Google Scholar