HCO3, the Bicarbonate ion, is the main alkaline factor in almost all water.
Alkalinity serves as a buffer, neutralizing acids. It is of no great significance in most situations, but it is a problem in areas like the beverage industry, boiler towers, cooling towers, and the textile industry. Excessive alkalinity, for example, can interfere with dying of textiles and it defeats the acidity of fruit flavors in beverages.
Alkalinity is a measure of the capacity of
water or any solution to neutralize or
“buffer” acids. This measure of acid neutralizing capacity is important in figuring
out how “buffered” the water is against
sudden changes in pH.
Alkalinity should not be confused with pH.
pH is a measure of the hydrogen ion (H
+
)
concentration, and the pH scale shows the
intensity of the acidic or basic character of a
solution at a given temperature. The reason
alkalinity is sometimes confused with pH is
because the term alkaline is used to describe
pH conditions greater than 7 (basic).
The most important compounds in water that
determine alkalinity include the carbonate
(CO3
2-
) and bicarbonate (HCO3 -) ions.
Carbonate ions are able to react with and
neutralize 2 hydrogen ions (H
+
) and the
bicarbonate ions are able to neutralize H
+
or
hydroxide ions (OH
-
) present in water. The
ability to resist changes in pH by
neutralizing acids or bases is called
buffering.
Treatment: Bicarbonate alkalinity can be reduced by aeration, which reduces free carbon dioxide. It can also be treated by feeding acid to lower pH. Strong Base Anion exchange also reduces alkalinity.
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