kinetic modeling of the Alkaline decomposition of potassium arsenojarosite

Mizraim Flores, Francisco Patiño, Iván A. Reyes, Isauro Rivera, Martin Reyes and Julio Juárez
J. Braz. Chem. Soc.,23:6, 1018-1023, 2012.


A sample of potassium arsenojarosite was synthesized and thoroughly characterized. The obtained sample is a solid solution of potassium arsenojarosite, whose approximate formula is [K0.75(H3O)0.25]Fe1.84[(SO4)1.82(AsO4)0.18][(OH)2.34(H2O)3.66]. The decomposition process in alkaline medium was studied in the induction and progressive conversion periods, and the reaction order and activation energy were determined for each case. Under the used experimental conditions, results are consistent with the spherical particle model with decreasing core and chemical control. In both processes, four partial models and two global models were developed in order to describe their basic behavior. The models were validated, and it was proved that they favorably describe the decomposition process in alkaline medium.