Estabilidade coloidal de etanossois de (hidr) oxidos de ferro (III)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1986

RESUMO

The iron (hidr)oxide sols obtained by oxidation of Fe(CO) 5 ethanolic solutions with H2O2 (aq.) were studied. The particles of these sols are amorphous, colloidally stable and have narrow size distribution.It is that the particle size can be controlled adjusting reaction conditions, by adition of acetic acid or sodium acetate. The reaction stoichiometry was studied analising the gases evolved during the process, and the final oxidation state of the iron ions formed. It was found that uncomplete conversion of carbon monoxide to carbon dioxide occurs, allowing to say that the actual reaction between the reactants is none of the originally proposed. The colloidal stability of the ethanossols was studied, by coagulation experiments of the Schmoluchowski type. Stability factors founded show that the colloidal stability of these sols is determined not only by eletrostatic, DLVO-type, forces. There are evidences that these sols can be also thermodinamically stabilysed. The acetic acid decomposition kinetics was followed. Results show that a first order (surface reaction) model is obeyed, and that the rate constant changes slowly with aging. Crystalization of the amorphous polymer was follwed by IR spectroscopy. The final phase present in water rich dispersions is goethite, a-FeOOH.

ASSUNTO(S)

oxido de ferro processos quimicos compostos organometalicos

ACESSO AO ARTIGO

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