Earth Planets Space, Vol. 56 (No. 12), pp. 1241-1245, 2004
Jun Kameda1, Kazuko Saruwatari1, Hidemi Tanaka1, and Fumiaki Tsunomori2
1Department of Earth and Planetary Science, Graduated School of Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
2 Laboratory for Earthquake Chemistry, Graduated School of Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
(Received May 31, 2004; Revised September 13, 2004; Accepted November 16, 2004)
The mechanism of hydrogen generation during the mechanochemical treatment of biotite was examined by grinding experiments using a ball mil in H2O or D2O as a grinding media. From the linear relationship between the amount of generated hydrogen and the increase of the surface area of ground powders, the hydrogen productivity of biotite is estimated to be 0.036mmol/m2, which agrees with the previous results in spite of the difference in the grinding conditions. D2 analyses by a mass spectrometry indicate that the produced amount of D2 accounts for only 10% of the total hydrogen and that more than 90% of hydrogen takes a form of a mixture of HD and H2. The observed isotope distribution clearly indicates that hydroxyls within the crystal structure can be a major source for the generation of hydrogen. Hydrogen generation originated from hydroxyls may indicate the higher hydrogen productivity of phyllosilicates than those of quartz and alkali feldspar.
Key words: Hydrogen generation, mechanochemical treatment, biotite, hydrogen isotope.