Solubilization of two organic dyes by cationic ester-containing gemini surfactants

A. R. Tehrani-Bagha, R. G. Singh, K. Holmberg*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

70 Citations (Scopus)


Solubilization of two different types of organic dyes, Quinizarin with an anthraquinone structure and Sudan I with an azo structure, has been studied in aqueous solutions of a series of cationic gemini surfactants and of a conventional monomeric cationic surfactant, dodecyltrimethylammonium bromide (DTAB). Surfactant concentrations both above and below the critical micelle concentration were used. The concentration of solubilized dye at equilibrium was determined from the absorbance of the solution at λ max with the aid of a calibration curve. The solubilization power of the gemini surfactants was higher than that of DTAB and increased with increasing alkyl chain length. An increase in length of the spacer unit resulted in increased solubilization power while a hydroxyl group in the spacer did not have much effect. Ester bonds in the alkyl chains reduced the solubilization power with respect to both dyes. A comparison between the absorbance spectra of the dyes in micellar solution with spectra in a range of solvents of different polarity indicated that the dye is situated in a relatively polar environment. One may therefore assume that the dye is located just below the head group region of the micelle. Attractive π-cation interactions may play a role for orienting the dye to the outer region of the micelle.

Original languageEnglish
Pages (from-to)112-118
Number of pages7
JournalJournal of Colloid and Interface Science
Issue number1
Publication statusPublished - 15 Jun 2012
MoE publication typeA1 Journal article-refereed


  • Anthraquinone dye
  • Azo dye
  • Ester bond
  • Gemini surfactants
  • Quinizarin
  • Solubilization
  • Sudan I

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