Simultaneous Removal of Coexisting Fe(II) and Cr(VI) from Wastewater by Electrocoagulation (EC) Process Using Different Types of Connection Modes

The current study describes the simultaneous removal of Cr(IV) and Fe(II) ions from wastewater by electrocoagulation (EC) process. Experiments were performed to evaluate a wide range of process conditions as electrode material, electrode connection mode, initial ion concentration (C o ), initial pH, current density (CD), salt dose (C s ), and electrode distance (IED) on the removal of coexisting Fe(II) and Cr(VI). Experimental results infer that to achieve 99.65% removal of Fe(II) ions and 99.91% Cr(VI) ions from initial concentration of 20 mg/L of Fe(II) and 40 mg/L of Cr(VI), CD of 12.93 mA/cm 2 , initial pH of 6, IED of 1 cm, and salt concentration of 0.33 g/L, using Fe/Fe electrode in monopolar connection is desirable. Electric energy consumption was found to vary significantly from 9.70, 50.80, to 65.90 kW/m 3 using monopolar (M), series monopolar (SM), and series bipolar (SB) connection mode respectively. Water quality analyses for turbidity, total dissolved solid (TDS), nitrate, sulfate, alkalinity chlorine, hardness, etc. amid EC process were assessed at varied operating parameters. Kinetics analysis indicates that removal of Fe(II) and Cr(VI) ions apparently follows first-order kinetic model. FESEM-EDX and XRD analysis shows the adsorption of iron and chromium ions and other contaminations in the sludge generated in the EC bath.