ELECTROOXIDATION OF LACTOSE ON PLATINUM AND ON MODIFIED PLATINUM-ELECTRODES IN ALKALINE-MEDIUM

In this preliminary work, the electro-oxidation of lactose was investigated by cyclic voltammetry in alkaline medium on platinum electrodes. Tafel slopes and variation of electrochemical parameters indicated that the electrocatalytic oxidation of lactose was controlled by diffusion. The current densities were small, but underpotential deposition of metal adatoms (Bi, Pb and Tl) was found to give rise to large increases in the current densities of lactose oxidation. One of these systems (eg Pt-Bi) was used to realize long-time electrolysis with a triple pulse potential programme. The analysis of solutions was performed by ionic chromatography (HPIC) at regular intervals during lactose oxidation. High selectivity was achieved and lactobionate was the sole reaction product detected, with a conversion rate of ca 70% of the initial lactose after only two hours of electrolysis.