Global kinetics of the alkaline oxidative degradations of lactose

Abstract

The kinetics of the “classical” and the anthraquinone-2-sulfonate (AMS) catalysed alkaline oxidative degradation of lactose and related carbohydrates have been investigated. Batch experiments were carried out at initial sugar concentrations from 100 to 375 mol m⁻³, AMS concentrations from 0 to 5 mol m⁻³, di-oxygen concentrations from 0.28 to 1.38 mol m⁻³, a pH from 11.5 to 13.5 and temperatures at 293 and 303 K. A reaction network is presented that accounts for the main products formed. Regression analysis of the experimental data, using a multi-response Marquardt algorithm, allowed the experimental data to be described adequately by a reaction sequence consisting of different oxidation pathways starting from the sugar enediolates and having the formation of the latter as the common, most important, rate-determining step.