Unlocking the Catalytic Efficacy of Cationic-Nonionic Mixed Micellar Scaffolds for Oxidative Transformation:...

This study provides an in-depth investigation of the stability and catalytic efficiency of mixed surfactant systems at various compositional ratios (2:3, 3:2, 1:1, 1:4, and 4:1) as sustainable media for Cr(VI)-mediated oxidation of 2-butanol. Two mixed micellar systems, (CTAB-Brij-35) and (CTAB-TX-100), were formulated by using commercially available surfactants: cationic CTAB, nonionic Brij-35, and TX-100. Various experimental studies, including surface tension, zeta potential, DLS, UV-vis, ¹H NMR, FT-IR, and FESEM, were conducted to attain the goal. The observed CMC values of the mentioned binary micelles were determined by the surface tension method. Additionally, this extensive study aims to investigate the micellar characteristics (β, X₁, f₁, f₂, surface charge, and ΔG_M^ex) of cationic-nonionic mixed micelles. The more negative interaction parameter (β) values for 1:1 CTAB-Brij-35 compared to 1:1 CTAB-TX-100 indicate a more synergistic interaction in the equimolar CTAB-Brij-35 system. Furthermore, CTAB surface charge neutralization is more noticeable at the equimolar ratio CTAB-Brij-35, revealing that the CTAB-Brij-35 system (1:1) exhibits more synergism than the CTAB-TX-100 system (1:1). The encapsulation of 2-butanol molecules into the mixed micelles was confirmed by the different interaction study (DLS, ¹H NMR, and FESEM). The 1:1 CTAB-Brij-35 mixed micellar system catalyzes the oxidation reaction with impressive efficiency, reducing the reaction time from ∼19 to ∼1 h, while the 1:1 CTAB-TX-100 reduces it to ∼1.5 h. Our study shows that the mixed micelle with an equimolar ratio (1:1) is the best composition among the mole ratios, resulting in the highest kinetic output.