On some mechanistic aspects of the electrochemical oxidation of lactose at platinum and gold electrodes in alkaline medium

The electrocatalytic oxidation of lactose was performed in alkaline medium at both platinum and gold electrodes. Electrolysis carried out on Au electrodes showed that the conversion yield decreases when the initial concentration of lactose increases. This does not affect the selectivity in the production of lactobionic acid which is evaluated to be nearly 100%. The kinetic study on lead modified platinum electrodes showed that the oxidation of lactose into lactobionic acid follows an overall first order law with k(0) = 8.2 x 10(-4) min(-1) cm(-2) An infrared reflectance spectroscopic investigation reveals the presence of a lactone intermediate at low potentials. On a gold electrode, the chromatographic analyses confirm the IR spectroscopic studies, leading us to assume that the reaction mechanism depends on the applied electrode potential. (C) 1997 Elsevier Science S.A.