CYLINDRICAL 3-DIMENSIONAL ELECTRODES UNDER LIMITING CURRENT CONDITIONS

Three-dimensional electrodes of cylindrical geometry, with current and electrolyte flows at a right angle, can be realized with an inner or outer position of the counter electrode. Furthermore, in the case of t he fluidized bed the performance of the electrode is also influenced b y the position of the current feeder. For the packed bed and the fluid ized bed the limiting current analysis has been applied to calculate t he variation of overpotential within the bed in relation to the penetr ation depth of the diffusion limited current density. Results obtained for both cylindrical geometries are compared with those of a rectangu lar electrode. In the case of a packed bed electrode the largest penet ration depth of the limiting current density is offered by the cylindr ical design with the counter electrode in an outer position. For fluid ized bed electrodes the situation is more complex, depending on the ra tio of the solution phase to the particulate phase resistance which is a function of the resistivity and the geometric parameters. However, the configuration with an outer counter electrode is generally more ad vantageous.