PREPARATION AND DECOMPOSITION OF AMMONIOJAROSITE AT ELEVATED-TEMPERATURES IN H2O-(NH4)(2)SO4-H2SO4 MEDIA

Ammoniojarosite samples were prepared at 368 and 483 K. The XRD patterns of these samples were identical, showing sharp peaks corresponding to d lines of reported ammoniojarosite. TG-DTA curves show that the decomposition of ammoniojarosite starts at similar to 643 K, with complete conversion to Fe2O3 at similar to 1073 K. Hydrothermal decomposition of ammoniojarosite was studied by varying H2SO4 concentration, time, temperature and (NH4)(2)SO4. It was observed that, depending on the acid concentration, the jarosite was stable up to 503 K. At 523 K complete decomposition of jarosite takes place within 3 h.