Effect of the electrode geometry on the performance of a batch electrochemical reactor used for Cr(VI) removal

The efficient removal of hexavalent chromium from aqueous media is a problem that has found a solution by electrochemical methods. In this work, the effect of electrode geometry on the performance of a stirred tank electrochemical reactor designed for this purpose is evaluated. Two electrode configurations are evaluated: static rings (SR) and electro baffles (EB). The electrodes installed in the batch reactor are static, so the stirring is done with a system of two impellers, whose distance between them is also a variable studied. Five cases are assessed. The evaluation of the cases contemplates experimental tests of Cr(VI) reduction to know its effect on the reaction rate and energy consumption. Computational fluid dynamics analysis is also performed to assess the hydrodynamic environment inside the reactor and relate it to experimental performance. The results show that the electrode geometry affects the Cr(VI) reduction rate as it promotes the process to be controlled by mass transfer. The hydrodynamic analysis shows that the process requires two aspects: an efficient circulation of the fluid inside the tank and homogeneous flow conditions in the vicinity of the electrode surface.