Study of Mn²⁺ and MnO₄⁻ products interaction in alkaline solution

Interaction of Mn²⁺ ions with MnO₄⁻ in alkaline medium is considered. The main component of this interaction is manganese oxyhydroxide MnO(OH) and not manganese dioxide, that is revealed by means of X-ray diffraction analysis, IR-spectrometry and chemical analysis. It is demonstrated that decomposition of MnO(OH) occurs in the wide temperature range (60-550 °C), that results in mixture of Mn₂O₃ and MnO₂ oxides formation

Formation characteristics of Fe₃O₄ magnetic particles precipitated from aqueous solutions and their sorption properties

Effect of temperature and iron concentration in solution on the phase composition, particle size, and magnetization was studied. It is shown that amount of the magnetite phase increases with the temperature increase. The magnetization slightly decreases with increase in the initial iron concentration. It is found that, regardless of the deposition conditions, spherical particles are formed, the average size of which varies within 7 to 15 nm. Comparison between the for removal efficiency and sorption capacity of the particles with the magnetite and hematite phase for cobalt was carried out. The sorption capacity of the particles is essentially independent of the phase composition and is about 18 mg/g for cobalt. For preparation of sorption material based on Fe₃O₄ magnetic particles, it is recommended to carry out the precipitation at the temperature of not lower than 80°C and the concentration of iron in solution of 0.15 to 0.3 M. The resulting particles comprise not less than 90 wt. % of magnetite phase and are characterized by magnetization of 65 to 70 A·m²/kg