Kinetic and Mechanistic Study of the Reduction of Chromium(VI) by Lactic Acid

Abstract

The kinetics and mechanism of the reduction of chromium(VI) by lactic acid (Lac) in aqueous acidic medium was studied with spectrophotometry in a temperature range of 298.15 K~313.15 K. Under the conditions of the pseudo‐first order ([Lac] 0 ≫ [Cr(VI)] 0 ), the observed rate constant ( k obs ) increased with the increase in [Lac] and [H + ]. There is no salt effect. Based on the experimental results, a probable reaction mechanism of oxidation was proposed. The rate equation derived from the mechanism could explain all the experimental phenomena. Activation parameters along with rate constant of the rate‐determining step have been evaluated.