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 (C_j), initial pH, salt dose, distance between electrodes (ID) and initial Cr(VI) concentration (C_i) 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, C_j 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.