horiba 5002S-10C, Инструкция по эксплуатации

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55
Reference
The abundance ratio between the ammonium ion NH
4
+
and ammonia NH
3
based on the pH value is shown in Fig. 5.
It is understood that when the pH value becomes 12 or more (alkalinity), most
of the ammonium ions NH
4
+
convert to ammonia NH
3
.
Fig. 5 Abundance ratio between
ammonia NH
3
and ammonium ion NH
4
+
Therefore, when the pH value of the sample solution to be measured is
adjusted to 12 or more, most of the ammonium ions NH
4
+
in the sample
solution are converted to ammonia NH
3
(gases dissolved in the aqueous
solution), and as a result, ammonia NH
3
can permeate through the membrane.
For example, when sodium hydroxide NaOH is added to the sample solution
and the pH is adjusted to 12 or more, ammonium ions NH
4
+
convert to
ammonia NH
3
through binding with hydroxide ions OH
-
.
Fig. 6 Conversion from ammonium ions NH
4
+
to ammonia NH
3
NH
4
+
+ OH
-
→ NH
3
(Gas) + H
2
O … (1)
100
ammonia NH
3
(gases dissolved in
the aqueous solution)
ammonium ions NH
4
+
50
0
6 7 8 9 10 11 12 13 14 (pH)
Existing ratio (%)
NH NH
4
+
NH
4
+
NH NH
3
(Gas) (Gas) NH
3
(Gas)
NaOH
Sample solution