STUDY OF BEHAVIORAL ABOUT THE DECOMPOSITION REACTION OF THE SOLID SOLUTION KFE3(SO4)2?X(CRO4)X(OH)6 IN CA(OH)2 MEDIA

The decomposition of the solid solution KFe3(SO4)2?x(CrO4)x(OH)6 and its capacity todetain CrO4 2? under alkaline conditions were studied. A solution of Ca(OH)2 was the media used. The incorporation of CrO42? in crystalline structure of jarosite, resulted in a solidsolution 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 datadescribe a reaction based in the model of decreasing core with chemical control.Decomposition curve shows an induction period, characterized by the formation of active centers where is initiated and established a reaction front, that is the beginning of the progressive conversion period, during which is formed a layer of inert products of Fe(OH)3and is characterized for the massive diffusion of K+, SO42? and CrO42? toward the solution.However, the mappings by SEM-EDS from a particle decomposed partially, shows that the SO42? is released preferentially, meanwhile, an important quantity of the CrO42? is adsorbedin the layer of Fe(OH)3.