The isomorphous substitution of Fe3+ for Si4+ in the tobermorite (Ca5Si6H2O18·4H2O) structure and its effects on the cation exchange properties of tobermorites were investigated. Fe3+- substituted 11Å tobermorites were synthesized under hydrothermal conditions. The cation exchange capacities of these Fe3+-substituted tobermorites ranged between 82-122 meq/100g while specific Cs sorption ranged from 420-800 Kd. 57Fe Mossbauer Spectroscopy, in addition to other techniques, was used to investigate the Fe-substitution in the tobermorite structure. None of the Mossbauer spectra revealed any absorption line due to Fe2+. The observed spectra were fitted to one or more closely overlapping quadrupole doublets. The assignment of Fe3+ among the available tetrahedral and octahedral sites was made based on the distinct differences in the observed isomer shifts. The extent of Fe3+IV vs. Fe3+VI site occupancies was determined from the corrected intensities of the respective quadrupole doublets.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering