Environmental leaching characteristics of scorodite synthesized with Fe(II) ions

The leaching characteristics of scorodite particles synthesized from Fe(II) under different conditions, such as reaction time and temperature, were investigated. The solution conditions, such as pH and temperature, were changed in leaching experiments. The results showed that the leaching characteristics depend on the synthesis temperature of scorodite particles, particle size, type of solvent and so on. Since the amount of As dissolved from particles with the high Fe/As molar ratio is relatively low, the Fe/As molar ratio of the particles is an important factor to control the dissolution of As from scorodite particles. The results of leaching tests with repeated renewal solution showed that pH of solution is the most important factor in the As dissolution. It was found that the addition of goethite to the scorodite is also effective to reduce the amount of As in solution.

► Scorodite with high Fe/As and 7-h reaction had low As solubility near pH=5.
► Scorodite with low S and 1-h reaction had low As solubility at pH=0–2.
► Scorodite had lower solubility than iron arsenate hydrate in NaCl solution.
► Consecutive As leaching in pH=6.86 buffer solution might converge to zero.
► Adding goethite to scorodite had the apparent effect of reducing the As leaching.