ARTÍCULO

SYNTHESIS AND TOPOLOGY OF THE REACTION OF MERCURY JAROSITE IN NAOH MEDIUM

Sayra Ordoñez, Francisco Patiño, Iván A. Reyes, Mizraim U. Flores, Victor H. Flores, Elia G. Palacios, Martín Reyes
Proceedings, European Metallurgycal Conference, EMC, Vol.1, Pag.537-552, ISBN 978-3-940276-61-2, 2015.

ABSTRACT:

In this work, we propose the slow addition of reagents to a Fe2(SO4)3·nH2O solution contained in a oneliter glass reactor, which in turn was immersed in oil in order to improve heat transfer. Hg(NO3)2·H2O was slowly added using different temperature, pH and stirring conditions. The obtained precipitates were vacuum filtered and rinsed with hot distilled water to remove the iron, sulfate and nitrate excess. A total of 11 syntheses were performed, and the obtained products were characterized by dichromatometry, gravimetry, Atomic Absorption Spectroscopy (AAS), X-ray diffraction (XRD) and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS), as well as Inductively Coupled Plasma Spectrometry (ICP). Of the syntheses we performed, synthesis number four is the one that presents optimal experimental conditions in order to obtain mercury jarosite: 0.27 mol L−1 Fe2(SO4)3·nH2O, 0.58 mol L−1 Hg(NO3)2·H2O, 93 °C (366 K) and 400 rpm mechanical stirring for 24 h. The synthesized sample has the approximate formula Hg0.4(H3O)0.2Fe2.71(SO4)2.17(OH)4.79(H2O)2.12; 9.59 grams of this compound were obtained. The study on the topology of the reaction of mercury jarosite in alkaline medium (NaOH) was conducted under the following conditions: 0.05 mol L−1 NaOH, pH 12.70, T 30 °C (303 K), d0 38 μm and 500 rpm magnetic stirring. SEM-EDS results indicate that the OH− ions diffuse from the bulk of the solution, through the ash layer, and towards the particle, while the (SO4)2− and Hg2+ ions diffuse from an unreacted core towards the solution, which suggests that the kinetic model that best describes the dissolution is that of constant size spherical particles and unreacted core.