Electrocoagulation as an Alternative for the Removal of Chromium (VI) in Solution

Abstract

Context: The contamination of water sources by the discharge of effluents contaminated with chromium (VI) is a current environmental problem because it is a toxic pollutant for humans, animals, plants, and microorganisms; it can be carcinogenic and has a high solubility in an aqueous environment. This research aims to study the electrochemical removal of hexavalent chromium by electrocoagulation using iron and aluminum electrodes with monopolar configuration, evaluating the effect of residence time, voltage, and the number of electrodes on the removal efficiency.
 Methodology: The experiments were conducted in a 3L batch electrocoagulation cell, using 10 and 6 aluminum and stainless steel plates as electrodes, connected at a distance of 1.5 cm in a monopolar configuration in parallel to the power source. Contaminated solution with Cr (VI) was treated at a concentration of 50 mg/L, evaluating two levels of residence time (20 and 30 min), voltage (20 and 30 V), and the number of electrodes (6 and 10 electrodes).
 Results: After the electrocoagulation removal tests, it was obtained removal percentages between 60.15 and 92.9%. The most significant positive variable in the process was the increase in the residence time. It can be inferred that electrocoagulation performs better at lower voltages and longer residence times and that the joint effect of the increase of the number of electrodes and the contact time would increase the performance of the process, achieving greater removal.
 Conclusions: The process of reduction of chromium (VI) by electrocoagulation has the potential to be used for the cost-effective removal of heavy metals from water