STUDIES ON THE DISSOLUTION OF HEMATITE SOL IN MIXTURES CONTAINING COMPLEXING AND REDUCING AGENTS

This study deals with the dissolution of monodispersed spherical haema tite sol (particle size similar to 130 nm) in a mixture of organic che lating and reducing agents, viz., EDTA, ascorbic acid and citric acid at pH 2.8 at 353 K and evaluation of the dependence of the dissolution rates on the concentration of each of the individual constituents of the mixture. The study based on the 'grain model' shows a linear depen dence of dissolution rate on EDTA concentration; in the case of citric acid the concentration dependence is not linear but tends to level of f at concentrations above 33 mol m(-3). The dissolution rate decreases as ascorbic acid concentration is increased from 11 - 22 mol m(-3) an d reaches a limiting value with further increase in ascorbic acid conc entration.