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Technology |
Henry’s law states that, at a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
A formula for Henry's Law is:
where:
- C = the gas consentration in water
- H = the solubility of the gas in water
- p = the partial pressure of gas in air
While the proportion of oxygen and nitrogen in air is approximately 1:4, it is approximately 1:2 in water. The solubility of gas in water is dependent on a variety of factors:
- The solubility of a gas in water is directly dependent upon the pressure at the surface between gas and water. If we choose to base the solubility of a gas, such as oxygen, on the conditions of contact between air and water in an open basin, it is dependent on the prevailing atmospheric pressure. It is possible to increase the pressure, and the quantity, of dissolved gas by injecting it at a certain depth. The greater the depth is, the more efficient the transfer will be.
- An increase of temperature reduces the ability of water to dissolve oxygen.
- Impurities in water reduce oxygen solubility when compared with water that is free from impurities. Impurities include salt, pollutants, organic substances etc. It is especially important to note that saturated seawater contains less oxygen than saturated freshwater.
- The size of the contact area between gas and water is of crucial importance: the larger the contact area, the more readily oxygen is dissolved. In additional to this, turbulence in both the aqueous and the gaseous state can increase the rate of dissolution.
Pressure, contact area and turbulence are factors used to increase the efficiency of oxygenation systems. |
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| Ove Gjelstenli |
| Telephone: | +47 22 02 77 17 |
| Fax: | +47 22 02 77 01 |
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