CFD and experimental validation of an electrochemical reactor electrode design for Cr(VI) removal

Pollution caused by Cr(VI) in water is an important social concern owing to the harmful effects of Cr(VI) on human health and the environment. Electrochemical treatment with rotating carbon steel electrodes has previously been used to remove Cr(VI), but drawbacks such as high power consumption, construction difficulties, and costly maintenance have discouraged its implementation at an industrial level. Therefore, it is vital to develop a more efficient and practical electrochemical reactor to remove this type of pollutant from aqueous media. In this work, the performance of an electrochemical reactor electrode design was assessed for the removal of Cr(VI) from aqueous media. Static carbon steel electrodes were incorporated to reduce power consumption and two electrodes designs were tested, namely ring electrodes (C1) and bar electrodes (C2). In the case of C2, the electrodes also acted as baffles in the stirred tank. Agitation was provided by standard four-blade 45° pitched blade turbine impellers. Computational fluid dynamics analysis and experimental measurements of torque, mixing, and treatment time were conducted to evaluate the performance of the electrochemical reactor using the proposed configurations. Compared with the previous design, the new configurations reduced treatment time and energy consumption. Further, the wall shear stress was calculated to estimate electrode passivation.