Investigation of Influencing Factors and Mechanism of Antimony and Arsenic Removal by Electrocoagulation Using Fe–Al Electrodes

Exposure to antimony (Sb) and arsenic (As) through contaminated surface water poses a great threat to human health. In this work, Sb and As were removed simultaneously by electrocoagulation (EC) using Fe–Al electrodes. The effects of current density, pH, initial concentration, aeration intensity, and anions were investigated. A higher current density achieved better removal performance. The optimum pH range was 5.0–7.0. Sb and As removals were slower at higher initial concentrations. Preoxidation was beneficial to As removal, whereas anoxic conditions were more favorable for Sb removal. Nitrate and sulfate had little influence on the performance of the EC process, but significant inhibition was observed in phosphate-rich solutions. Scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis demonstrated that adsorption onto iron and aluminum hydroxides/oxyhydroxides was the predominant mechanism involved in Sb and As removal. Finally, over 99% of Sb and As were removed from a practical wastewater sample, indicating that EC using Fe–Al electrodes provides an alternative method for Sb and As removal.