ABSORPTION OF OXYGEN INTO AQUEOUS ALKALINE SUSPENSIONS OF FERROUS HYDROXIDE LEADING TO FORMATION OF EXTREMELY FINE GOETHITE AND MAGNETITE PARTICLES

The absorption of oxygen into aqueous alkaline suspensions of ferrous hydroxide leading to formation of extremely fine goethite and magnetite particles was performed using a bubble column with draft tube. The overall oxidation rates in both the systems were found to be promoted by the solid dissolution in the liquid film around a gas bubble even in this gas dispersed equipment, and were compared with prediction on the basis of a film-theory model incorporating the diffusion, the chemical reaction and the solid dissolution as the parallel steps. The trend of augmentation of the enhancement factor due to the solid dissolution could be represented by this modified model. © 1990, Taylor & Francis Group, LLC. All rights reserved.