FERRIC HYDROUS OXIDE SOLS .3. PREPARATION OF UNIFORM PARTICLES BY HYDROLYSIS OF FE(III)-CHLORIDE, FE(III)-NITRATE, AND FE(III)-PERCHLORATE SOLUTIONS

The methods of preparation of ferric hydrous oxide sots consisting of particles, uniform in shape, of narrow size distribution are described in detail. To produce such sots, acidic solutions, containing ferric ions and nitrate, perchlorate, or chloride ions, respectively, were aged at elevated temperatures for times ranging from a few hours to a few weeks. Solids formed from the solutions containing chloride consisted of either β-FeOOH or α-Fe2O3 depending on the concentration of ferric and chloride ions, whereas particles generated in solutions containing nitrate or perchlorate ions consisted of α-Fe2O3. Particle shape varied greatly as the conditions of colloid preparation were altered. It was possible to produce systems consisting of cubic, ellipsoidal, pyramidal, rodlike, and spherical particles. Such dispersions differed greatly in color. Complete domains are given in terms of ferric salt and corresponding acid concentrations which delineate regions of particle formation of given chemical composition and shape. Electrokinetic measurements show relatively small difference in point of zero charge for the various sots studied. © 1978 Academic Press, Inc.