Hydrothermal synthesis and stability evaluation of mansfieldite in comparison to scorodite

In this work, the hydrothermal synthesis and stability evaluation of mansfieldite (AlAsO4·2H2O) is described. The synthesis involves hydrothermal precipitation at 160 °C from equimolar (CAl = CAs = 0.3 M) Al (III) – As (V) nitrate solutions over a period of 24 hours. X-ray diffraction (XRD) characterization showed the synthesized mansfieldite material to have the same structural characteristics (crystal lattice parameters) with the mansfieldite mineral. The product, upon examination with field emission gun scanning electron microscope, field emission gun variable pressure scanning electron microscope and field emission gun transmission electron microscope, was found to consist of individual crystals of 1 to 4 μm.Long term leachability studies (up to six weeks) in the pH range 5 to 9 at 22 °C determined mansfieldite to be more reactive than scorodite and hence not a satisfactory carrier for the fixation of arsenic in the environment.