Simultaneous Studies of Redox Reaction of Chromium(VI) and Arsenic(III) in Aqueous Phase: A Kinetic and Mechanistic Approach

A kinetic and mechanistic approach was used to simultaneously study the oxidation of As(III) and reduction of Cr(VI) in aqueous phase, and in the presence of Fe(III). Reactions were monitored by UV-visible spectrophotometry. The stoichiometry of the reaction was 11111111.PNG. The rate equation for the reaction is proposed as 2222221.PNG where k2 is the second order rate constant. The reaction was not affected by Fe(III) ions within the studied concentration range of 0.001 – 0.009 molL-1. From the reaction between 3331.PNG a plausible mechanism involving an ester formation by the reactants leading to the eventual formation of As(V) and Cr(III) was proposed.