Effect of the ultrasonic irradiation on the Cr(VI) electroreduction process in a tubular electrochemical flow reactor

The electroplating, leather tanning, and textile industries are facilities that discharge wastewaters contaminated with high concentrations of Cr(VI), which is carcinogenic and has negative health effects. Low-cost technologies to remove this pollutant must be generated with high-efficiency reactors. Electrochemical Cr(VI) reduction is a low-cost alternative process, which has been studied and applied with success at the laboratory level. In this work, the hydrodynamic behavior of the fluid into the sonoelectrochemical tubular flow reactor with spiral-helicoid-wire low-cost electrode material (carbon steel) was evaluated. The fluid behavior was evaluated by computational fluid dynamics (CFD). In addition, the dispersion the reactor was evaluated experimentally and by CFD. The reactor presented large dispersion that was considered into the model to describe the sonoelectrochemical process to reduce the Cr(VI) in wastewaters. Moreover, an empirical model to describe the electrochemical reduction of the Cr(VI), with and without ultrasonic irradiation, was validated experimentally at different pHs.