Study on the process and mechanism of nickel from wastewater by sinusoidal alternating current electrocoagulation

• 1、College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410006

Abstract：Nowadays, with increasing of heavy metal pollution and water consumption, the shortage of freshwater resources is one of the greatest challenges human facing. The electroflocculation method has great advantages in the sustainability and low-cost treatment in industrial polluted wastewater treatment. In this paper, the sinusoidal alternating current flocculation with double-iron electrode was used to remove the Ni2+ from wastewater. In addition, the removal efficiency of the Ni2+ was studied by optimizing the electrocoagulation parameters. Operating parameters have a great influence on electroflocculation performance. Under the optimal parameters, the possible mechanism of sinusoidal alternating current electrocoagulation removing Ni2+ was explored. The results indicated that electrolysis time was 25 min, the number of reactors was 5, current density was 7 mA/cm2 and initial pH of 7, 100 mg/L of Ni2+ wastewater could be effectively treated. The Ni2+ content was 0.440 mg/L and corresponding removal rates were 99.56%, which met the GB21900-2008 emission standards (total nickel content <1 mg/L). The floc produced by sinusoidal alternating current flocculation exhibited fine nanospheres with larger specific surface area by analyzing the surface morphology. It was found that the process of iron hydroxide floc adsorbing nickel forms many complex hydrates, which had the characteristics of poor amorphous crystallinity.

Keywords： Wastewater treatment Nickel ion Sinusoidal alternating current Electrocoagulation Operating parameters