Regeneration of hexavalent chromium from a simulated rinse etching solution using an electrochemical reactor with two compartments separated by a ceramic membrane

Abstract

[EN] The performance of a batch electrochemical reactor with two compartments separated by a ceramic diaphragm for the regeneration of Cr(VI) from a simulated rinse etching solution has been studied under constant cell voltage mode and in galvanostatic operation. The effect of the applied current (I) and cell voltage (U) on the Figures of Merit (fractional conversion, current efficiency, space-time yield and specific energy consumption) for the Cr(III) to Cr(VI) electrochemical oxidation is analyzed. As both I and U parameters increase, the current efficiency () for the electrochemical oxidation of Cr(III) is decreased due to the oxygen evolution side reaction, which causes an increment in the specific energy consumption (Es). On the other hand, an increment of the values of I and U leads to greater values of both Cr(III) fractional conversion (X) and space-time yield () due to the oxygen turbulence-promoting action. Comparing the results obtained under both operation modes, in galvanostatic operation higher values of X,  and  coupled with lower values of Es are obtained. Hence, working in galvanostatic operation at a relatively low applied current (1.5A) is the optimum option since the energy consumed is quite low, the current efficiency is relatively high and the amount of Cr(VI) recovered is close to 70%.