In chemistry, sparging, also known as gas flushing in metallurgy, is a technique which involves bubbling a chemically inert gas, such as nitrogen, argon, or helium, through a liquid. This can be used to remove dissolved gases (e.g. oxygen) from the liquid. By Henry's Law, the amount of dissolved gases in a liquid depend on the partial pressure of the gases exposed to the liquid. Sparging increases the gas-liquid interface.
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Liquid chromatography
Solvents used in high performance liquid chromatography (HPLC) are often sparged with helium.
Engineering
In biochemical engineering, sparging can also be a method to remove low-boiling liquids from a solution. The low-boiling components tend to evaporate more rapidly, hence they may be removed from the bulk solution containing higher-boiling components. It is an alternative to distillation, and it does not require heat.
Environmental chemistry
This technique is also used in environmental chemistry to extract the oil contaminants from subsoil water and the ground.
Metallurgy
In metallurgy, this process is used to remove dissolved gases from the melt prior to the material being processed. For example, before casting aluminium alloys, argon bubbles are injected into liquid aluminium using a rotary degasser. The resulting argon bubbles will rise to the surface bringing with them a quantity of the dissolved hydrogen. This degassing treatment reduces the occurrence of hydrogen gas porosity.