Dissolved gases are gases that are naturally present in water or absorbed from the surrounding air. Common dissolved gases include carbon dioxide, oxygen and nitrogen. In laboratory water purification, carbon dioxide is often the most important dissolved gas because of its effect on resistivity and ion exchange resin life.
Even after water has been purified, it can absorb carbon dioxide from air during storage or dispensing. This is one reason why storage tank design, tank vent filtration and recirculation are important in high-purity water systems.
Dissolved gases may come from:
Carbon dioxide dissolves in water and forms weak carbonic acid. This can dissociate into ionic species, increasing conductivity and reducing resistivity.
Dissolved carbon dioxide can reduce the apparent resistivity of purified water even when the water has low levels of other ionic impurities. It also increases the load on deionization cartridges because ion exchange resins must remove the ionic species formed from dissolved carbon dioxide.
This can cause:
Dissolved oxygen may also be important in certain analytical or electrochemical applications, although it is usually less critical than carbon dioxide in standard laboratory water systems.
Dissolved gases can be controlled by:
For systems requiring very high resistivity stability, degassing may be used before or after deionization stages.
Dissolved gases may affect:
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TKA Ultrapure Water Technologies India Pvt. Ltd. is an Indian company focused on the design, manufacture and support of laboratory water purification systems… Read More
