FORMATION OF FUNCTIONAL FINE PARTICLES BY GAS-LIQUID REACTION

In the formation of acicular and spindle-shape goethite (alpha-FeOOH) and acicular lepidcrocite (gamma-FeOOH) fine particles by air oxidatio n of aqueous suspensions of ferrous species, the particle size based o n the major axis has been found to be proportional to the oxidation re action rate raised to the power -0.30 similar to -0.44. This functiona l relationship was interpreted on the basis of the concept that the nu cleation rate can be expressed as m-order in supersaturation of an int ermediate species, polynuclear ferric hydroxo-complex.