Comparative interaction of an anionic dye, ponceau 4R with triple viz., anionic, non-ionic and cationic micellar systems: Spectral and conductometric analysis

Abstract

In this work, the interaction of ponceau 4R dye (P4R) with triple viz., anionic, nonionic and cationic micellar systems has been studied. The three surfactants employed were nonionic pluronic L-64 (PL-64), anionic sodium dodecyl sulphate (SDS) and cationic cetyl trimethyl ammonium bromide (CTAB). All the three dye - surfactants systems were investigated through UV - visible spectroscopy, conductivity, FT-IR, pH effect and SEM studies. There was short and strong bonding between the dye and all the three types of micelles as observed from FT-IR studies. The conductivity studies displayed greater interaction with CTAB than with SDS. The free energy of micellization, ∆G was observed to be -16.07 kJ mol−1 for P4R+ CTAB and -13.83 kJ mol−1 for P4R + SDS, demonstrating greater spontaneity and stability of the former combination. This can be explained due to strong electrostatic attraction between negatively charged P4R dye and positively charged micelle of CTAB. Overall, the anionic ponceau 4R dye has been successfully incorporated into the nonionic, anionic and cationic micellar systems. This is probably the first report of interaction of a similarly charged dye and surfactant system.