DISSOLVED-OXYGEN CONCENTRATION IN AN UNDIVIDED ROTATING CYLINDER ELECTRODE REACTOR

The steady state mass balance for dissolved oxygen in an undivided rot ating cylinder electrode reactor was established. Cases involving the absence or presence of a diffusion controlled oxygen reduction reactio n were treated. The results show that in the absence of the oxygen red uction reaction and under low electrolyte velocities employed industri ally, the rotating cylinder electrode reactor, exhibiting a continuous stirred tank reactor behaviour, yields lower dissolved gas concentrat ions than a plug flow reactor. Therefore, the rotating cylinder electr ode reactor leads to lower redissolution rates of the detached metalli c particles by oxygen corrosion. The effect of the dissolved gas conce ntration in the inlet electrolyte also demonstrates the benefits of a prior degassing step in the flow sheet. The simpler equation derived i n the absence of oxygen reduction may be used in its presence for inle t dissolved oxygen concentrations below saturation and industrially re levant electrolyte velocities ranging from approx. 0 to 0.3 m s-1 if m etal deposition current efficiency is higher than 87% or, conversely, if the dissolved metal concentration to dissolved oxygen concentration ratio is greater than 27. An even simpler equation based on the added hypothesis of total desorption of the gas produced can also be used w ith electrolyte velocities below 0.025 m s-1. Finally, the derived equ ations allow optimization of the rotating cylinder electrode reactor.