Dynamical modeling of the electrochemical process to remove Cr (VI) from wastewaters in a tubular reactor

Abstract

This work is aimed at obtaining and calibrating a dynamical model of the electrochemical reduction of Cr(VI) in a tubular continuous reactor with a spiral wire shaped anode at different conditions of pH (1.0 to 2.0) and residence times. An industrial wastewater sampled from a Mexican electroplating industry with about 1000 mg dm-3 of Cr(VI) was used for the experiments. It was found that pH exerts a strong influence on the performance of electrochemical reduction of Cr(VI). Thus at a wastewater influent pH = 1.0 and a residence time in the reactor of 38.5 min it is possible to reduce the Cr(VI) concentration from 1000 to 0.37 mg dm-3. However at an influent pH higher than 1.5, an effluent Cr(VI) concentration lower than 0.5 mg dm-3 cannot be obtained. A more complete dynamic model was applied incorporating pH and the dispersion effects that affect the electrochemical Cr(VI) removal. The model, which adequately describes the performance of the electrochemical process, can be used to optimize the performance of this kind of reactor with more reliability. © 2007 Society of Chemical Industry.