234
C. De Stefano· C. Foti . A. Gianguzza . D. Piazzese . S. Sammartano
Table 9.9. Parameters of Eq. 9.4 for the dependence on salinity of apparent protonation constants' of
amines, at t= 25·C
Amine
logTKi H
°i
°2
°3
en
9.91
0.003714
dien
9.80
0.003178
trien
9.67
0.001211
tetren
9.83
-0.000768
sper
10.70
0.000056
en
2
6.86
0.1594
-0.01958
0.00114b
dien
2
8.74
0.1481
-0.01865
0.00114
trien
2
8.87
0.1756
-0.02001
0.00114
tetren
2
9.01
0.1324
-0.01895
0.00114
sper
2
9.70
0.1260
-0.01932
0.00114
dien
3
3.66
0.4452
-0.06523
0.00344b
trien
3
6.12
0.3824
-0.06102
0.00344
tetren
3
7.73
0.3251
-0.05445
0.00344
sper
3
8.32
0.3368
-0.05403
0.00344
trien
4
2.38
0.8332
-0.1675
0.01095
tetren
4
3.90
0.7031
-0.1301
0.00812
sper
4
7.22
0.6003
-0.1114
0.00688
tetren
5
1.88
1.0958
-0.2321
0.01562
a Refer to the reaction: iH+ + A 0 ~ H/+.
b The parameter 03 was constrained, for i = 2, 3, to be constant for all the amines.
The parameters of Eq. 9.4 depend on: (i) the protonation step (mainly), i.e. the
charge of the protonated species; and (ii) the number of amino groups in the amine,
nN' For i = 1, ... 3, we have the following relationships, which are valid for all the amines
studied:
10gKr = 10gT Kr* + 5 (0.00722 - 0.00159 nN)
(9.8)
log~* = 10gTKr + 5 112 (0.179 - O.0077nN) - 0.02175 + 0.0014353/2
(9.8a)
10gKr = 10gTKr + 5 112 (0.500 - 0.0346nN) - 0.05145 + 0.002465312
(9.8b)
The decrease in apparent protonation constants with increasing salinity was accounted for by considering the formation of complex species between protonated
amines with A 1.117-. In all the amine-BA systems, the species B(am)I.117+ and
(am)Alf/·ll7-i) (with i = 1, ... , n; n = number of aminogroups) are formed. Formation
constants for amine-BA complex species are shown in Table 9.10.