Synthesis of well-crystallized birnessite using ethylene glycol as a reducing reagent

Well-crystallized birnessite sheets containing K+ in the interlayers have been prepared using KMnO4, ethylene glycol and KOH by microwave heating at 90 °C for 10 min. Ethylene glycol was used as a reducing agent. The effect of KOH concentration on the formation of birnessite was studied. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TG), differential scanning calorimetric analysis (DSC) and Fourier transform infrared (FTIR). Birnessites were converted to cryptomelane upon heating at 400–800 °C and completely collapsed to form Mn3O4 at 1000 °C.