[Zero-Valent Iron (ZVI) Activation of Persulfate (PS) for Oxidation of Arsenic (Ⅴ) Form Aqueous Solutions]

Arsenic is one of the most toxic substances yet discovered and arsenic contamination of water has become a global environmental problem in need of a solution. This study has identified the capacity of sodium persulfate (PS), activated by zero-valent iron (ZVI) to remove As(Ⅴ) from waste-water is much greater than the capacity of PS alone due to the production of sulfate radicals in the process. Five parameter types including PS and ZVI dosage, reaction temperature, initial pH value, and initial As(Ⅴ) concentration are discussed in detail. These parameters affect the removal rate dynamics as an influencing factor of the As(Ⅴ) concentration. The material structure before and after the reaction was characterized by X-ray photoelectron spectroscopy analysis (XPS) and scanning electron microscopy (SEM). It was demonstrated that under this solution of 20-100 mg·L^-1 of As(Ⅴ), the removal rate of As(Ⅴ) is more than 98% and a pseudo-second order kinetic model can be used to describe the reaction. The removal mechanism of ZVI/PS to As(Ⅴ) was explored by comparing the results of X-ray photo-electron spectroscopy of samples taken before and after reaction with ZVI/PS. PS can accelerate the corrosion of ZVI and then promote the adsorption of As(Ⅴ), moreover, it can also form precipitates and coprecipitates with iron oxide/hydroxide to achieve an enhanced removal of As(Ⅴ).