title: Alkaline decomposition of synthetic jarosite with arsenic.
abstract: The widespread use of jarosite-type compounds to eliminate impurities in the hydrometallurgical industry is due to their capability to incorporate several elements into their structures. Some of these elements are of environmental importance (Pb(2+), Cr(6+), As(5+), Cd(2+), Hg(2+)). For the present paper, AsO4 (3-) was incorporated into the lattice of synthetic jarosite in order to carry out a reactivity study. Alkaline decomposition is characterized by removal of sulfate and potassium ions from the lattice and formation of a gel consisting of iron hydroxides with absorbed arsenate. Decomposition curves show an induction period followed by a conversion period. The induction period is independent of particle size and exponentially decreases with temperature. The conversion period is characterized by formation of a hydroxide halo that surrounds an unreacted jarosite core. During the conversion period in NaOH media for [OH(-)] > 8 × 10(-3) mol L(-1), the process showed a reaction order of 1.86, and an apparent activation energy of 60.3 kJ mol(-1) was obtained. On the other hand, during the conversion period in Ca(OH)2 media for [OH(-)] > 1.90 × 10(-2) mol L(-1), the reaction order was 1.15, and an apparent activation energy of 74.4 kJ mol(-1) was obtained. The results are consistent with the spherical particle model with decreasing core and chemical control.
authors.affiliation: Centro de Investigaciones en Materiales y Metalurgia, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo km. 4.5, Pachuca, Hidalgo, C.P. 42184, Mexico.
authors.forename: Francisco
authors.initials: F
authors.lastname: Patiño
authors.affiliation: Centro de Investigaciones en Materiales y Metalurgia, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo km. 4.5, Pachuca, Hidalgo, C.P. 42184, Mexico.
authors.forename: Mizraim U
authors.initials: MU
authors.lastname: Flores
authors.affiliation: Centro de Investigaciones en Materiales y Metalurgia, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo km. 4.5, Pachuca, Hidalgo, C.P. 42184, Mexico.
authors.forename: Iván A
authors.initials: IA
authors.lastname: Reyes
authors.affiliation: Centro de Investigaciones en Materiales y Metalurgia, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo km. 4.5, Pachuca, Hidalgo, C.P. 42184, Mexico.
authors.forename: Martín
authors.initials: M
authors.lastname: Reyes
authors.affiliation: Centro de Investigaciones en Materiales y Metalurgia, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo km. 4.5, Pachuca, Hidalgo, C.P. 42184, Mexico.
authors.forename: Juan
authors.initials: J
authors.lastname: Hernández
authors.affiliation: Centro de Investigaciones en Materiales y Metalurgia, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo km. 4.5, Pachuca, Hidalgo, C.P. 42184, Mexico.
authors.forename: Isauro
authors.initials: I
authors.lastname: Rivera
authors.affiliation: Centro de Investigaciones en Materiales y Metalurgia, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo km. 4.5, Pachuca, Hidalgo, C.P. 42184, Mexico.
authors.forename: Julio C
authors.initials: JC
authors.lastname: Juárez
keywords: Activation energy; Alkaline decomposition; Kinetics; Reaction order; Synthetic jarosite with arsenic