Micellar behaviour of sodium dodecyl sulfate in presence of a cationic dye

Abstract

It has been known for more than three-fourth of a century that indicator dyes have their colours altered when present in solutions along with soaps or detergents. The interaction of dye with surfactants leading to colour change has been attributed to novel effect which makes the detergents differ from other electrolytes (1) to the formation of ionpairs (2) of micelles (3) of an insoluble complex (4, 5) the presence of dyedimers and high aggregates with one or more soap molecules (4) of insoluble dye-detergent complex and induced micelles (6). The formation of a very insoluble salt between ionic dyes and oppositely charged detergent is a very general phenomenon (9). Many dyes in the above reference have been taken as a source of determination of cmc but, other shown a strong interaction with surfactant micelles.