Micellar flocculation for the treatment of synthetic dyestuff effluent: Kinetic, thermodynamic and mechanistic insights

Abstract

This research work is an attempt to evaluate the role of micellar flocculation (MF) for the treatment of dye-contaminated water. Solubilization of dye by organized assemblies of anionic surfactants and its subsequent complexation with the metal cations during flocculation has been found as the active phenomena in this treatment methodology. Base soap (BS) being a mixture of anionic surfactants along with the salt of the divalent cation (Ca2+) was employed to capture and separate the reactive dye, reactive red 195 (RR-195), in the form of flocs at optimized concentrations of soap, dye, and flocculant. The effect of contact time, temperature, pH, and electrolyte has also been investigated to figure out the optimum conditions necessary to perform this adsorptive removal. The surface characteristics of adsorbent and favorability of adsorption were evaluated with the help of different isotherm models i.e., Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin. Furthermore, kinetic and thermodynamic calculations were performed for a better understanding of the nature of the said removal. Herein, the results reveal that this removal process is spontaneous, favorable, and exothermic. The excellent removal of RR-195 (≈99%) through micellar flocculation suggests that it’s an economical, sustainable, and efficient approach for the treatment of industrial effluent containing dyes.