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 (Pb2%2b, Cr6%2b, As5%2b, Cd2%2b, Hg2%2b). For the present paper, AsO43- 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. © 2013 Patiño et al.; licensee BioMed Central Ltd.

authors

• Flores M.U.
• Hernández J.
• Juárez J.C.
• Patiño F.
• Reyes I.A.
• Reyes M.
• Rivera I.

publication date

• 2013-01-01

published in

• Geochemical Transactions  Journal

keywords

• Activation energy; Alkaline decomposition; Kinetics; Reaction order; Synthetic jarosite with arsenic activation energy; arsenic; decomposition; ion; iron hydroxide; jarosite; lattice dynamics; particle size; potassium; reaction kinetics; sulfate

Digital Object Identifier (DOI)

• 10.1186/1467-4866-14-2

start page

end page

volume

• 14

issue

• 1