A multisectioned porous electrode for synthesis of D-arabinose

A multisectioned flow-through porous electrode, consisting of alternating conducting and insulating sections, was designed, built, and tested for the electrosynthesis of D-arabinose in aqueous solution. The laboratory prototype, consisting of ten independent porous graphite slices each of 5 mm thickness, can be adapted by external electrical connection to allow both traditional and sectioned operations to be run in a single device. The experimental study in this work focuses on use of the multisectioned arrangement to improve current-distribution uniformity in the porous-electrode reactor. A model electrosynthesis system, consisting of oxidation of sodium gluconate to D-arabinose in competition with the parallel reaction of oxygen evolution, has been chosen for investigation. Measurements in the sectioned electrode show that the performance, expressed in terms of current efficiency for gluconate oxidation, increases Significantly with an increase in the number of sections. A comparison of predicted theoretical performance with experimental measurements on the ten-section prototype has been used to extrapolate the performance of the sectioned electrode to configurations with larger numbers of sections. Extrapolation indicates that optimal performance in the 5 cm electrode can be achieved with fewer than 100 sections, a design that is feasible to construct with modem microfabrication technology. (C) 1999 The Electrochemical Society. S0013-4651(98)08-021-5. All rights reserved.