pH Dependance of Scorodite Formation in As(V) Solution Using Magnetite as the Solid Iron Source

Arsenic-containing wastewater, which is mainly generated in nonferrous metal-smelting plants, threatens the natural environment and human health owing to its high toxicity and mobility. A promising arsenic immobilization method to solve this problem is to immobilize arsenic as scorodite. In this study, the method of scorodite synthesis using magnetite as the iron source was investigated, which can be performed using low-cost materials under atmospheric pressure without using an autoclave. The generation and crystallization behaviors of the intermediate of the gel-like precursor of scorodite were investigated by monitoring the concentration of each iron ion in solution and characterizing the precipitate. By clarifying the effect of the solution pH for each reaction step, the mechanism and suitable conditions of this process are discussed.