FORMATION OF SPINDLE-SHAPE GOETHITE EXTREMELY FINE PARTICLES BY AIR OXIDATION OF AQUEOUS SUSPENSION OF FERROUS SPECIES

Abstract

Spindle-shape goethite (a-FeOOH) extremely fine particles were produced by air oxidation of an aqueous suspension consisting of a mixture of FeS0₄ and Na₂CO₃ at 30-40°C, using a standard-type bubble column. The time dependences of the fractional oxidation of total Fc(II7rpar; were measured under various combinations of experimental conditions. The shape and size (i.e., major and minor axes) of prepared a-FeOOH particles were observed with the aid of transmission electron microscopy. From such measurements and observations, the mechanism of spindle-shape a-FeOOH particle formation was deduced; the total number of a-FeOOH nuclei is fixed in the early stage of the oxidation reaction, and subsequently, only the particle growth tends to take place until leading to the final size, depending on the reaction condition, i.e., reaction rate.

Keywords:

• Goethite
• spindle-shape
• particle growth
• size control
• bubble column

Additional information

Notes on contributors

H. KUMAZAWA

Address for correspondence: Faculty of Engineering, Toyama University, 3190 Gofuku, Toyama 930, Japan.