Synthesis of Todorokite

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Science  14 Feb 1986:
Vol. 231, Issue 4739, pp. 717-719
DOI: 10.1126/science.231.4739.717


Todorokite of chemical composition (Mg0.77Na0.03)(Mg0.18Mn2+0.60Mn4+5.2222) O12·3.07 H2O was synthesized by a two-step procedure. First, sodium birnessite was synthesized and magnesium was exchanged for sodium to form magnesium birnessite, which was autoclaved under a saturated steam pressure at 155°C for 8 hours to form well-crystallized todorokite. Synthesized todorokite particles consisted of fibers extending from a central plate. The plate itself was made of twinned fibers forming a trilling pattern. The infrared spectra and x-ray diffraction patterns were similar to those of natural todorokite samples. Calcium birnessite and nickel birnessite, when autoclaved under conditions similar to those for magnesium birnessite, yielded a todorokite structure. However, the formation of todorokite from calcium and nickel birnessite was less extensive.

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