Buserite, layer structures

MnOj X HjO with a crystallographic layer structure, the interval between the layers is 10 A). This mineral is called Buserite or Todorokite . It displays strong ion exchange properties especially for transition metals. The ion exchange decreases in following order Cu, Co, Zn, Ni, Na, Ca, Mg . ... 

In the conventional precipitation and sol-gel routes, the resultant bimessite or buserite materials are usually Na type or K type, in which the cations are located in the interlayers, and MnOe octahedral units form the Cdl2-type structure in the layers. The stmcture and propaties of bimessite and buserite can be modified to load other cations, including alkali metals, alkaline earths, and transition metals, via two pathways. One pathway is interlayer substitution via ion exchange method at room temperature [14,22]. In this process, Na- or K-bimessite are stirred in a solution of dopants. Divalent metal cations, such as Mg ", Ni ", Co ", have been successfully ion exchanged with Na-birnessite mataials and used to prepare todorokite-type materials with tunnel stractures [22],... 

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