PMID- 16852465
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20070724
LR  - 20060720
IS  - 1520-6106 (Print)
IS  - 1520-5207 (Linking)
VI  - 109
IP  - 24
DP  - 2005 Jun 23
TI  - Thermodynamics and kinetics of hydroxide ion formation in 12 CaO x 7 Al2O3.
PG  - 11900-6
AB  - We have examined the thermodynamics and kinetics of hydroxide (OH-) ions that 
      formed in cages of 12 CaO x 7 Al2O3 (C12A7) with nanoporous structures. It is 
      confirmed using thermogravimetric-evolved gas analyses (TG-EGA) that hydration in 
      C12A7 is mediated by a reaction between an oxide (O2-) ion in the cage and an H2O 
      molecule in the atmosphere to form two OH- ions in the cages. To simply and 
      exactly quantify the OH- content from infrared absorption measurements of 
      OH-stretching band, we propose a method combined with a thermodynamic analysis, 
      allowing the simultaneous determination of the molar extinction coefficient of 
      the OH-band, enthalpy, and entropy for the hydration. Hydration enthalpy in C12A7 
      is extremely high compared with other oxides and was enhanced by the marked 
      instability of O2- ion in the cage. Consequently, high solubility of OH- ion is 
      retained up to unusually high temperatures. Furthermore, we determined diffusion 
      coefficients of species relevant to the hydration process and demonstrated that 
      inward diffusion of OH- ions is the rate-determining process.
FAU - Hayashi, Katsuro
AU  - Hayashi K
AD  - Frontier Collaborative Research Center, Tokyo Institute of Technology, S2-13, 
      4259 Nagatsuta, Yokohama 226-8503, Japan. k-hayashi@lucid.msl.titech.ac.jp
FAU - Hirano, Masahiro
AU  - Hirano M
FAU - Hosono, Hideo
AU  - Hosono H
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Phys Chem B
JT  - The journal of physical chemistry. B
JID - 101157530
EDAT- 2006/07/21 09:00
MHDA- 2006/07/21 09:01
CRDT- 2006/07/21 09:00
PHST- 2006/07/21 09:00 [pubmed]
PHST- 2006/07/21 09:01 [medline]
PHST- 2006/07/21 09:00 [entrez]
AID - 10.1021/jp050807j [doi]
PST - ppublish
SO  - J Phys Chem B. 2005 Jun 23;109(24):11900-6. doi: 10.1021/jp050807j.