Alkaline Decomposition of Solid Solution of Ammonium-Sodium Jarosite with Arsenic

In this study, a solid solution of arsenical ammonium-sodium jarosite, with the approximate formula [(NH4)0.72 Na0.06(H3O)0.21]Fe3(2.52)(SO4)1.85 (AsO4)0.15 [(OH)4.41 (H2O)1.59], was synthesized. The precipitate particle main size 38 µm, spherical morphology. A decomposition reaction in alkaline media carried out; comprised three stages: an induction period, progressive conversion and stabilization period. process controlled by chemical reaction, period consistent shrinking core model. dissolution reactions compound NaOH were characterized ash layer formed residues made Fe(OH)3 adsorbed arsenate surrounding unreacted through which Na+, NH4+ SO42− ions diffused into solution. At same time, OH− from front until disappeared, indicating end reaction.