Kinetics of Manganese Oxides Dissolution in Sulphuric Acid Solutions Containing Oxalic Acid
- 1 Moscow State Engineering University (MAMI), Moscow, Russia
- 2 Moscow State Engineering University (MAMI), Moscow, Russia
- 3 Moscow State Engineering University (MAMI), Moscow, Russia
Abstract
The kinetics of the interaction of MnO 2 , Mn 2 O 3 , and Mn 3 O 4 , with sulphuric acid solutions and the effect of oxalic acid on this process are studied. As the sulphuric acid concentration is increased from 0.1 to 5 N, the dissolution rate of Mn 2 O 3 , Mn 3 O 4 to MnO 2 and Mn 2+ ions decreases, whereas it increases with the concentration of Mn 2+ ions. Upon the addition of H 2 O x , the complete dissolution of Mn 3 O 4 occurs more quickly. The reaction order with respect to the H + and O x 2- ions is +0.5 ± 0.1. A mechanism of MnO 2 dissolution promotion by O x 2- is proposed. The dissolution rate was found to depend on the concentrations of MnHO x - ions and was highest at pH 1.6 ± 0.2. A rate law and mechanism are suggested for manganese oxides dissolution.
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