Kinetics and mechanism of chromic acid oxidation of oxalic acid in absence and presence of different acid media. A kinetic study

Abstract

Kinetics and mechanism of the reaction of Cr (VI) where only undissociated oxalic acid is kinetically active. Kinetic evidence for the formation of a Cr(VI)9 oxalic acid 1 : 1 complex has been obtained and the equilibrium constant for their formation has been determined. The 1 : 1 complex exists most likely in an open chain form. The rate-limiting step of the oxidation reaction involves the breaking of the C9 C bond in the 1 : 2 complex. Oxidizing ability of Cr(VI) species have been discussed. Mechanism with the associated reaction kinetics is assigned.

Cooxidation of anilides and oxalic acid by chromic acid: A one-step, three-electron oxidation

“…Fast Ϫ иCO ϩ Cr(VI) 9 9 : Cr(V) ϩ CO 2 2 Fast Cr(V) ϩ (COOH) 9 9 : 2CO ϩ Cr(III) 2 2 Earlier studies lend strong support for this scheme [20]. The activation enthalpies and entropies of the oxidation of benzanilides by Cr(VI) in the presence of oxalic acid in aqueous acetic acid medium are linearly related (Table III).…”

Removal of Chromium from a Contaminated Soil Using Oxalic Acid, Citric Acid, and Hydrochloric Acid: Dynamics, Mechanisms, and Concomitant Removal of Non-Targeted Metals

“…Previous studies have shown OX to have a significant role in both Cr(VI) reduction and Cr(III) complexation [14,44,45]. CA also can increase the reduction of Cr(VI) and the subsequent formation of soluble Cr(III)-citrate [45], and solubilize the Cr(III) by complexation and desorb the Cr(VI) by competition for surface sites [24].…”