Application of Piszkiewicz model on the electron transfer reaction of dithionite ion and bis-(2-pyridinealdoximato)dioxomolybdate(IV) complex

Abstract

The need to better understand the binding mode of antioxidants (sulfur oxyanions) kinetically is a concern in medicine. Hence, a spectrophotometric method was used to study the application of the Piszkiewicz model on the electron transfer reaction of dithionite ion (S2O42−) and bis-(2-pyridinealdoximato)dioxomolybdate(IV) complex at 303 K and an absorption maxima of 560 nm. It follows an acid dependent reductive pathway that is medium sensitive. Charge distribution from the reaction species contributes to the redox efficiency of the system, resulting in a primary salt effect (NaCl) with an enhanced reaction rate. Alteration of the reaction medium with ethanol led to an elevation of reduction time as the charge catalysis was distorted by a drop in the system permittivity. Likewise, sodium dodecyl sulfate in the system decreased the reduction rate of the complex due to the low impact of hydrophobic and ion interaction between the micelle and substrates. First order reaction kinetics was observed in the concentration of the redox partners and a 2:1 (complex: S2O42−) stoichiometry was obtained with the involvement of hydrogenated sulfite radical which resulted in the formation of sulfur dioxide and a Mo2+ deactivated complex. The occurrence of counterion catalysis is pronounced in the reaction system owing to the participation of like-charged substrates in the rate-controlling phase. The standard enthalpy (69.12 $$\pm$$ ± 0.05 kJ mol−1) and Gibbs energy (80.10 $$\pm$$ ± 0.07) kJ mol−1 suggest that the process is endothermic dependent. The investigation of the anionic surfactant effect on the reaction medium was quantitatively ascertained from the Piszkiewicz model of the complex interaction sequence.

Degradation of indigo carmine dye with peroxydisulphate ion in aqueous sulphuric acid phase: Kinetic study

“…In the oxidation of IC with peroxydisulphate ion; carbon dioxide and sulphur dioxide were tested by the involvement of six drops of limewater in the 0.3 cm −3 of the product solution, and a filter paper was dipped into an acidified 0.5 mol dm −3 K 2 Cr 2 O 7 solution, and it was transferred into the solution of the completed reaction mixture respectively. [24][25][26][27][28][29] Also, sulphonated anthranilic acid was identified via precipitation method as Zn(II) salt, Zn(C 7 H 7 O 5 NS) 2 . 30 By observing the absorbance decline of the dye at its λ max using a UV-visible spectrophotometer, the reaction rate of the IC with the oxidant was achieved.…”