Effects of synthesis parameters on the formation of birnessite-type manganese oxides

The optimum conditions for preparation of Na-birnessite, both for room temperature synthesis process and the hydrothermal synthesis process are presented. The synthesis parameters which include concentration of NaOH solution, aging conditions, drying conditions for the room temperature process, and reaction temperature and concentration of NaOH solution for the hydrothermal process were investigated by X ray diffraction analysis and scanning electron microscopy. The X ray diffraction show that the structures of manganese oxides are dependent on the NaOH/Mn(NO3)2 mole ratio. The crystal water in the 1.00 nm layered phase is readily dehydrated from the interlayer space.