Premium
Bordeaux‐R interactions with surfactants: thermochromic investigations of proton ionisation in cationic, nonionic and anionic surfactant solutions
Author(s) -
Khamis Mustafa I,
Jumean Fawwaz H,
Savelieff Masha G
Publication year - 2007
Publication title -
coloration technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 1472-3581
DOI - 10.1111/j.1478-4408.2007.00101.x
Subject(s) - thermochromism , pulmonary surfactant , cationic polymerization , chemistry , ionization , nonionic surfactant , proton , micelle , critical micelle concentration , analytical chemistry (journal) , aqueous solution , chromatography , organic chemistry , ion , biochemistry , physics , quantum mechanics
Apparent thermodynamic parameters for the hydroxy proton ionisation of Bordeaux‐R were obtained in micellar solutions using the thermochromic method. The effect of addition of the surfactants CTAB, TX‐100 and SDS was investigated in buffered solutions in the pH range of 6–13. Ionisation constants in water and in the presence of surfactants were determined spectrophotometrically and the p K ′ of Bordeaux‐R in water was found to be 10.90 in the absence of surfactant. However, at concentrations above critical micelle concentration, p K ′ dropped to 10.14 with CTAB, increased to 11.29 with TX‐100 but was insensitive to SDS addition. Standard enthalpies and entropies of ionisation were obtained using the thermochromic method. This method, in conjunction with p K and spectral measurements and comparison with different azo dyes, has been shown to provide detailed information on the mechanism of dye–surfactant interaction.