Hydrothermal Synthesis of Clay Minerals from Ground Talc

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In order to investigate the hydrothermal synthesis of clay minerals, mechanochemically activated ground talc was hydrothermally treated with various salt solutions. Results obtained are as follows ;1. Talc was changed into X-ray amorphous material by the grinding using a vibrating mill. However, 29Si-NMR data showed that this amorphous material contains a cluster of original layr structure of talc.2. Tri-octahedral smectite and poorly crystallized talc are formed from the ground talc by the hydrothermal treatment with Na salts (NaOH,Na_2CO_3, NaHCO_3, and NaCl) solutions or distillled water at 200 or 250ﾟC for 168 hours. However, no sepiolote was obtained.3. In the Hydrothermal treatment with Al salt (AlCl_3, Al(NO_3)_3, Al_2(SO_4)_3, and NaAlO_2) solutions at 200 or 250ﾟC for up to 240 hours, products were differed depend on the Al to Si (in the starting material) ratio and pH conditions. In the acidic condition, tri-octahedral smectite was formed in the case of low Al/Si ratio. In the medium Al/Si ratio, di-octahedral smectite was formed. Kaolinite was formed in high Al/Si ratio. On the other hand, tri-octahedral smectite was formed in the low Al/Si ratio and serpentine was obtained in the high Al/Si ratio, in basic condition.