Synthesis of porous Mn₃O₄ microparticles by the KMnO₄–AC reduction and combustion system

ABSTRACT

A direct method to synthesize porous hausmannite (Mn₃O₄) microparticles by the KMnO₄–AC reaction and combustion system is reported in this paper. In order to synthesize the manganese oxide, four experimental factors were considered: pH (3.0, 4.5 and 6.0), AC content (2.08 × 10⁻² and 8.33 × 10⁻² M), initial Mn(VII) content (4.55 × 10⁻⁴ and 9.1 × 10⁻⁴ M) and stirring velocity (300 and 500 rpm). The AC was added to the Mn(VII) aqueous solution and stirred for 2 h. For different pH levels, the Mn(VII) content in the solution was measured by UV/Vis spectrometry at 540 nm in order to evaluate the Mn reduction. Later, the manganese-loaded AC was calcined at 700°C in dry air at 1900 sccm during 60 min, indicating that the Mn₃O₄ content is directly proportional to the acidity of the solution. Spongy and porous Mn₃O₄ microparticles were synthesized considering the following levels: pH (3.0), an AC content (8.33 × 10⁻² M) and an initial Mn(VII) content (9.1 × 10⁻⁴ M) with 500 rpm.

KEYWORDS:

• Activated carbon
• hausmannite
• manganese oxide microparticles
• permanganate ions
• synthesis

Acknowledgments

The authors thank the financial support of CONACyT project CB2010-155444 and CONACyT project INFT-2009-01-123861 to carry out this research.