Synthesis and catalytic activity of Birnessite-Type Manganese Oxide synthesized by solvent-free method

Redox reaction between KMnO₄ and glucose usingsolvent-free method produces the octahedral layer birnessite-type manganese oxide. The effects of mole ratios, temperatures, and calcinations time on the structures and crystallinity of the oxides were studied throughthe X-ray powder diffraction analysis. The mole ratio of KMnO₄/glucose (1:3) produces the purebirnessite with low crystallinity, whereas the mole ratio of KMnO₄/glucose (3:1) yields high crystalline birnessite with minor components of hausmannite-type manganese oxide.The increasing of the temperature and calcinations times (300-700 °C and 3-7 h, respectively) willimprove the crystallinity and the purity of the as-synthesized oxide. Further experiments also showed that the as-syntesized octahedral layer birnessite-type manganese oxides have catalytic activity on the degradation of methylene blue (MB) dye with H₂O₂ as oxidant. The results revealed that the effective degradation could be achieved only in the presence of both the birnessite and H₂O₂, whereas without the addition of catalyst (H₂O₂only) or addition of H₂O₂ (catalyst only), the 3.5% and 15.5% of MB removal were obtained, respectively. (paper)