292
M. E. Sastre de Vicente· T. Vilariiio
Table 11.2. Recipe of sea water and other parameters used for calculations
Sea water ions
Ionic Concentration c,
(f= (fo + ac; + bc~
(molr')
(fo (A)
a(Amor'l)
b(Amor 2 1 2 )
Na+
0.92146 C'W
3.77
-0.190
0.0246
K+
0.02034 C'W
3.42
-0.327
0.0503
Mg2+
0.10573 C'W
6.41
-0.214
0.00448
ci+
0.002068 C'W
5.78
-0.0107
0.0201
CI
1.08246 C'W
3.056
SO
0.05608 C'W
2.981
Dielectric constant: Er= Eo -8l, + b,3/2 with 8= 19.57 ±0.081 mol-' and b =4.6 ±0.1 13/2 mol- 3 / 2 (from
Vilarino and Sastre de Vicente 1999).
I Kl = II; O;(y;) I
I Modeling Q;(y;) I
I
I
Semiempirical Models
Statistical mechanical
· Pitzer (17)
approaches
· Guggenheim (18)
. Mean spherical
· Scatchard (19)
approximation
· Quassi-Lattice (20,21)
Origin
Debye-Huckel theory or
Integral equation theories
Quassi-Lattice model
Equation type
Explicit functions in I
Implicit (not functions in I)
Obtained parameters
Coefficients from linear
No coefficients
regression
Solution by Newton-Rhapson
Effect of physical-chemical
Not straightforward
Straightforward
parameters:
· Charge
· Concentration
· Diameter (Volume, Surface)
· Dielectric constant
Fitting of data
Good
Good
Numerical difficulty
Low
Low
Fig. 11.2. Comparison of different aspects associated to MSA and other approaches
theory is used for the calculation of the salting coefficient of amines from pK* data.
On the other hand, the MSA approximation is applied to predict the size of alkylamines
in that media, assuming a hard sphere contribution for the activity coefficient of the
neutral molecule of alkylamine. These data are compared to those calculated from
molar volumes proposed by several authors and taking neutral molecules as spheres.