Kinetics of Leaching of Iron Oxide in Clay in Oxalic Acid and in Hydrochloric Acid Solutions

Abstract Iron oxide in samples of clay containing 8.15 % iron oxide was leached in aqueous oxalic acid and hydrochloric acid solutions. Leaching experiments were conducted in the temperature range of 40–80°C for times up to 90 minutes in 0.2 M to 2 M acid solutions. The mixed kinetic mechanism seemed to be the most appropriate model to fit the kinetic data of leaching in oxalic acid while product layer diffusion controlled reaction model seemed to be the most appropriate one for leaching in hydrochloric acid. The Arrhenius activation energy for leaching in oxalic acid was found to be 41.035 kJ/mole while that for hydrochloric acid was 50.82 kJ/mole