512 
PACIFIC SCIENCE, Vol. XX, October 1966 
TABLE l 
Composition and CEC of Synthetic Gels (Air-Dried Basis)* 
A! 
A 2 
Bi 
Bo 
b 3 
B 4 
Si0 2 
8.99 
30.82 
32.51 
41.58 
46.53 
48.38 
AI 9 O 3 
24.92 
22.96 
20.72 
12.54 
9.46 
7.48 
H 2 0 (LOI) 
11.86 
7.64 
6.69 
6.88 
5.86 
5.07 
h 2 o — 
47.03 
25.89 
27.64 
29.21 
30.87 
34.18 
Total 
92.80 
87.31 
87.56 
20.21 
92.54 
95.11 
Na 2 0 (by difference) 
7.20 
12.69 
12.44 
9-79 
7.46 
4.89 
Si/Al 
0.306 
0.671 
1.382 
2.814 
4.159 
5.487 
CEC (me./ 100 g) 
245 
455 
420 
292 
190 
120 
CEC/A1 
0.501 
1.01 
1.03 
1.19 
1.02 
0.82 
Approx, inflection 
point, pH 
6 
5 
5 
6 and 4 
4 
4 
* Analyst, Mr. H. Tenma. 
held on the silanol groups are in fact partly 
ammonium ions and partly ammonia molecules. 
The equilibrium in (14) is strongly favored 
to the left, and, as excess ammonium ions are 
removed from the equilibrium system, ammonia 
is liberated into the washing alcohol, dissolving 
in it as ammonia molecules. This is quite dif- 
ferent from the loss due to hydrolysis, in which 
cations are lost by replacement with protons 
produced by the dissociation of the dispersing 
medium, usually water. Dissociation of sodium 
ions into the washing alcohol seems to be pre- 
vented, probably because the proton activity in 
alcohol is too small to cause hydrolysis. 
© © © dj — i — — 1 
4 5 6 7 8 9 10 II 
pH 
Fig. 5. Exchange curves of synthetic aluminosilicate gels and a silica gel. From top, A 2 (©), B 4 (©), 
B 2 (©), A x (O), B 3 (O), B 4 (C) and silica gel ( ©). 
