Performance Evaluation of Electro coagulation in Removal of Hexavalent Chromium from Aqueous Solution
The growth in civilization and industrial activities has caused a number of environmental problems. Hexavalent chromium is of particular environmental concern due to its toxicity and mobility and is challenging to remove from industrial wastewater. It is a strong oxidizing agent that is carcinogenic and mutagenic and diffuses quickly through soil and aquatic environments. Parameters affecting the electro-coagulation process, such as applied voltage, distance between electrodes, pH, combination of electrodes (AL - AL, MS – MS, MS – AL) and Contact time of electro-processing – their influence on electrocoagulation were studied.
In the first stage, experimental studies were carried out using different electrode combinations (AL – AL, MS – MS and MS –AL) with initial metal concentrations of 50ppm, constant voltage and constant dosage of 0.5gms of NaCl as an electrolyte by varying distance between electrodes. In the second stage, studies were carried out at different initial pH of 2, 4, 6 and 8 under the optimum current density and optimum spacing between electrodes obtained in the first stage of experiments for all electrode combination.
Cr (VI) ion concentration were effectively reduced to 89% in 60 minutes contact time with AL – AL Electrodes at 15 volts, 98% removal in 30 minutes with MS – MS Electrodes and 99% in 60 minutes with MS – AL Electrodes at 15 volts for synthetic chromium solution. The studies also showed that the Mild steel – Mild steel and Mild Steel– Aluminium electrode combination were more effective in removal of Cr (VI) compared to Aluminium – Aluminium Electrode combination.
Finally, Electrocoagulation studies were carried out for industrial waste water using iron electrodes as well as iron – aluminium electrode combination. Mild Steel and Aluminium Electrode combination showed maximum Cr (VI) removal efficiency when compared to Mild Steel – Mild Steel Electrodes.
Keywords - Electro-coagulation, Hexavalent Chromium, MS – MS Electrodes, AL – AL Electrodes, MS – AL Electrodes.