Experimental synthesis of chlorite from smectite at 300 degrees C in the presence of metallic Fe
Experimental synthesis of chlorite from smectite at 300 degrees C in the presence of metallic Fe (in Chlorites; CNRS thematic school, Anonymous)
Clay Minerals (September 2003) 38 (3): 281-302
- alteration
- cation exchange capacity
- chemical reactions
- chlorite
- chlorite group
- clay mineralogy
- clay minerals
- experimental studies
- geochemistry
- high temperature
- iron
- metals
- montmorillonite
- Mossbauer spectra
- salinity
- saponite
- SEM data
- sheet silicates
- silicates
- smectite
- solution
- spectra
- synthesis
- TEM data
- temperature
- X-ray diffraction data
The alteration and transformation behaviour of montmorillonite (bentonite from Wyoming, MX-80) in low-salinity solutions (NaCl, CaCl (sub 2) ) in the presence of metallic Fe (powder and 8X4X1 mm plate) and magnetite powder was studied in batch experiments at 300 degrees C to simulate the mineralogical and chemical reactions of clays in contact with steel in a nuclear waste repository. The evolutions of pH and solution concentrations were measured over a period of 9 months. The mineralogical and chemical evolution of the clays was studied by XRD, SEM, Transmission Mossbauer Spectroscopy and TEM (EDS, HR imaging and EELS). Dissolution of the di-octahedral smectite of the starting bentonite was observed, in favour of newly formed clays (chlorite and saponite), quartz, feldspars and zeolite. The formation of Fe-chlorite was triggered by contact with the metallic Fe plate and Fe-Mg-chlorite at distance from the Fe plate (>2 mm).
