Effect of cationic surfactant on Ru(III) catalyzed L-glutamic acid oxidation by hexacyanoferrate(III)

Abstract

In CTAB micellar medium, the kinetic investigation of Ru(III) promoted oxidation of L-glutamic acid (Glu) by [Fe(CN)₆]³⁻ was carried out by recording the decline in absorbance at 420 nm, which corresponds to [Fe(CN)₆]³⁻. By adjusting one variable at a time, the progression of the reaction has been inspected as a function of [OH⁻], ionic strength, [CTAB], [Ru³⁺], [Glu], [Fe(CN)₆³⁻], and temperature using the pseudo-first-order condition. The findings demonstrate that [OH⁻], [CTAB], and [Glu] are the key parameters that have a discernible impact on reaction rate. In the studied concentration range of Ru(III), [Fe(CN)₆]³⁻, and at lower [Glu] and [OH⁻], the reaction displays first-order kinetics. The incremental trend in reaction rate with electrolyte concentration demonstrates a positive salt effect. CTAB substantially catalyzes the process, and after reaching a maximum, the rate remains nearly constant at increased [CTAB]. The observed decline in the CMC of CTAB may be caused by the reduced repulsion between the positively charged heads of the surfactant molecules caused by the negatively charged OH⁻, and [Fe(CN)₆]³⁻. The activation parameters also support the outer-sphere electron transfer mechanism as recommended by us.