Abstract
Spindle-shape goethite (α-FeOOH) fine particles which can be used as a starting material for maghemite (γ-Fe2O3) were produced by air oxidation of aqueous suspension of ferrous carbonate at an alkali molar ratio of 2 and temperatures of 40 to 55°C using a bubble column. The oxidation rate can be expressed apparently as zero-order in the concentration of total Fe(II) and first-order in the concentration of dissolved oxygen up to the fractional oxidation of 0.8 as in case of the formation of acicular goethite particles by a similar reaction method. The particle size based on major axis decreased with increasing reaction rate. At an initial loading of Fe(Il), the particle size could be correlated well with the reaction rate alone