Novel atmospheric scorodite synthesis by oxidation of ferrous sulfate solution. Part II. Effect of temperature and air

We have previously reported a novel method for producing stable scorodite (FeAsO4·2H2O) under atmospheric conditions in which ferrous sulfate was oxidized by oxygen in the presence of high concentrations of arsenic(V). This work examines the effects of reaction temperature (95, 70, 50 °C) and the oxidizing agent (air, pure oxygen gas) to optimize scorodite formation in a practical process. Crystalline scorodite of low solubility could be prepared at 70 °C within only 7 h using either oxygen or air sparging and small particles were even formed at 50 °C using air oxidation.