Removal of Hexavalent Chromium from Wastewater by Electrocoagulation (EC): Parametric Evaluation, Kinetic Study and Operating Cost

This work reports the results of experimental work to evaluate the effect of current density (Cj), initial pH, salt dose, distance between electrodes (ID) and initial Cr(VI) concentration (Ci) for efficient removal of Cr(VI) from wastewater using batch electrocoagulation (EC). Experimental results show that Fe/Fe electrode combination with initial pH of 4.0, Cj of 43.103 A m−2, ID of 1.0 cm and NaCl dose of 0.33 g L−1(conductivity: 912 µS cm−1) are desirable operating parameters to reduce Cr(VI) contamination of wastewater from 40 mg L−1 to below 0.05 mg L−1 after 60 min of EC. Kinetic analysis for Cr(VI) removal by EC follows first-order kinetic model. Sludge generated from the EC bath was characterized using FESEM and EDX analysis. Further, estimated energy consumption for EC was calculated as 1.78 kWh m−3 with electrode utilization of 0.0057 kg m−3 and operational cost of 0.1517 US$ m−3.