Removal of Ni(II) and Cr(VI) Ions From Electroplating Wastewater Using Ferrous Sulfate

Background: In this study, the ferrous sulfate was used to remove Cr(VI) and Ni(II) ions from a real Ni-Cr plating industry wastewater. Methods: This is an applied study. The type of sampling was composite by three 5 L containers. Wastewater chemical and physical characteristics were measured in accordance with the standard methods. The concentration of un-removed metal ions was estimated by ICP-OES. The Jar test was used to carry out the chemical coagulation experiment. The results indicated that the rate of removal depended on the pH of 1.5-11, the diverse contact time of 30-120 min, and the coagulant measurement ranging from 0.5-2 g/L. Results: The optimum removal of Cr(VI) ions was observed at a pH of 7 up to 83.88% in 0.5 g/L of coagulant for 40 min. While the optimum removal of Ni(II) ions was found at a pH of 5 up to 56.33 % in 0.5 g/L of coagulant for 40 min. The scanning electron microscopy results revealed the difference between the coagulant surface while coagulation. Also, the Energy-Dispersive X-ray spectroscopy (EDX) analysis showed the presence of Cr(VI) and Ni(II) ions on the surface of the ferrous sulfate after coagulation. Conclusion: Ultimately, the results indicated that ferrous sulfate could be an operative chemical coagulant to remove Cr(VI) and Ni(II) ions from the plating industry wastewater, especially for Cr(VI) particles. The results of this study can be a useful guide to the real plating industry wastewater treatment operators.