Handbook of Solvents - George Wypych - ChemTech - Ventech!

21.3 Oxide solubilities in ionic melts 1495
N
pI ll = pI l + log
N
n +
Me , l l
n +
Me , l
[21.3.22]
where:
pN n+ , N n+ molar fractions of the most acidic cation in non-studied and the studied melts,
Me , ll Me , l
respectively.
21.3.4.3 The estimation of effect of temperature
The pP value obtained according the above equations can be corrected for temperature if it
differs from 700 o C. It has been shown that at relatively small temperature changes oxide
solubility is close to value predicted by the Shreder’s equation. 37 This allows one to estimate
the solubility products at different temperatures using the following equation:
pP = pP −
T2T* Tmp( T −T
)
( T * + T )
52 . * 2
where:
T* temperature at which pPT* is known
T2 temperature at which pP should be estimated
Tmp melting point of the oxide
21.3.5 CONCLUSIONS
2
[21.3.23]
The existing data allow
• to estimate level of contamination of melts by oxide containing impurities
• to predict oxide solubility in molten salts having different anion composition and
acidic properties
It should be emphasized, however, that there are problems which require further work:
• quantitative estimation of surface effect on oxide solubility
• the removal of oxide ion admixtures by the their conversion to oxide deposit.
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