Kinetic Analysis of the Decomposition of the KFe3(SO4)2-x(CrO4)x(OH)6 Jarosite Solid Solution in Ca(OH)2 Medium

Journal of the Brazilian Chemical Society

Patiño, Francisco¹  Reyes, Iván A.¹  Flores, Mizraim U.¹  Gutiérrez, Emmanuel J.¹  Mireles, Ister¹  Consejo Nacional de Ciencia y Tecnología, México, Mexico¹  Flores, Víctor H.¹  Universidad Politécnica Metropolitana de Hidalgo, Tolcayuca, Mexico¹  Unidad Profesional Adolfo López Mateos, México, Mexico¹  Reyes, Martín¹  Universidad Tecnológica de Tulancingo, Tulancingo, Mexico¹  Acosta, Manuel¹  Universidad Autónoma del Estado de Hidalgo, Mineral de la Reforma Hidalgo, Mexico¹  Universidad Juárez Autónoma de Tabasco, Cunduacán, Mexico¹  Cruz, Roel¹  Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico¹ 

关键词:  jarosite;    chromate ion;    solid solution;    dissolution rates;    kinetics analysis;   

DOI  :  10.5935/0103-5053.20150357

学科分类：化学（综合）

来源: SciELO

【 摘 要 】

The decomposition of the solid solution of potassium jarosite with chromium(VI) in Ca(OH)2 media was studied in the present work. According to experimental results, the incorporation of CrO42- into the crystal structure of jarosite resulted in a solid solution with the following approximate formula: [K0.86(H3O)0.14]Fe2.67[(SO4)1.23(CrO4)0.77][(OH)5.01(H2O)0.99]. The experimental data describe a reaction based on the shrinking core model with chemical control for spherical particles. A reaction order of n = 0.67 and an activation energy (Ea) of 63.75 kJ mol-1 were obtained in the induction period (tind). The progressive conversion period is characterized by the diffusion of K+, SO42- and CrO42- ions into the solution. In this stage, n = 1.99 with respect to OH-, and Ea = 51.56 kJ mol-1. The CrO42- diffusion is slower compared to that of sulfate, a slight amount of chromate is adsorbed in the layer of the solid residue consisting on Fe(OH)3. Finally, the equations that satisfactorily describe the reaction process were established from the data obtained.

【 授权许可】

Unknown