Interaction of Methyl Orange with Submicellar Cationic Surfactants

Abstract

Abstract The interaction of aqueous Methyl Orange (MO), an azo dye, with alkyltrimethylammonium and N-hexadecylpyridinium halide surfactants in submicellar concentration ranges has been investigated. The interaction gives rise to a new absorption band of MO with a maximum at ca. 370 nm, and the appearance of the new band has been attributed to change in the chromophore microenvironment in water structure enforced closely packed ion pairs of the dye with submicellar cationic surfactant. The strength of the interaction depends on the alkyl chain length of the surfactant, the surfactant head group and the counter ions.