Kinetic Study of Ru(III) Promoted Oxidation of L-Tryptophan in an Anionic Surfactant Medium by Hexacyanoferrate(III)
Abstract. The kinetic investigation of Ru(III) promoted oxidation of L-tryptophan (Trp) by [Fe(CN)6]3- has been performed in anionic sodium dodecyl sulfate (SDS) micellar medium by recording the decrease in absorbance at 420 nm, corresponding to [Fe(CN)6]3- using UV-visible spectrophotometer. Pseudo-first-order condition has been used to examine the progress of reaction as a function of [Fe(CN)6 3-], ionic strength, [OH-], [SDS], [Ru3+], [Trp], and temperature by changing one variable at a time. The results exhibit that [OH-], [SDS], and [Trp] are the decisive parameter showing an appreciable effect on reaction rate. The reaction exhibits first- order kinetics in the studies concentration range of Ru(III), [Fe(CN)6]3- and at lower [Trp] and [OH-]. The incremental trend observed in the reaction rate with electrolyte concentration shows a positive salt effect. The reaction rate is almost ten times faster in SDS micellar medium compared to the aqueous medium. [Fe(CN)6]3- does not show any appreciable effect on the critical micellar concentration (CMC) of SDS as the polar head of SDS and [Fe(CN)6]3- both are negatively charged. The K+ obtained from K3[Fe(CN)6] and KNO3 decreases the repulsion between the negatively charged heads of the surfactant molecules thereby decreasing the CMC of SDS. The activation parameters also support the outer-sphere electron transfer mechanism as proposed by us.
| Main Authors: | , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedad Química de México A.C.
2023
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| Online Access: | http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1870-249X2023000100046 |
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