In
chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...
, sparging, also known as gas flushing in
metallurgy
Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys.
Metallurgy encompasses both the sc ...
, is a technique in which a
gas is bubbled through a
liquid
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
in order to remove ''other''
dissolved gas(es) and/or dissolved
volatile liquid(s) from that liquid. It is a method of
degassing. According to
Henry's law, the concentration of each gas in a liquid is proportional to the partial pressure of that gas (in the gaseous state) in contact with the liquid. Sparging introduces a gas that has little or no partial pressure of the gas(es) to be removed, and increases the area of the
gas-liquid interface In the physical sciences, an interface is the boundary between two spatial regions occupied by different matter, or by matter in different physical states. The interface between matter and air, or matter and vacuum, is called a surface, and studied ...
, which encourages some of the dissolved gas(es) to
diffuse into the sparging gas before the sparging gas escapes from the liquid. Many sparging processes, such as solvent removal, use air as the sparging gas. To remove oxygen, or for sensitive solutions or reactive molten metals, a chemically inert gas such as
nitrogen,
argon, or
helium is used.
Liquid chromatography
Solvents used in
high-performance liquid chromatography (HPLC) are often sparged with helium.
Engineering
In
biochemical engineering, sparging can remove low-boiling liquids from a solution. The low-boiling components evaporate more rapidly, so the gas bubbles remove more of them from the bulk solution containing higher-boiling components. It is an alternative to
distillation, and it does not require heat.
Environmental chemistry
In
environmental chemistry, air sparging is an ''in situ'' remediation technique that removes volatile pollutants from contaminated
groundwater and soil.
Metallurgy
In
metallurgy
Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys.
Metallurgy encompasses both the sc ...
, gas flushing removes dissolved gases from the
molten metal prior to the material being processed.
For example, before casting
aluminium alloys, argon bubbles are injected into liquid aluminium using a rotary
degasser. The argon bubbles rise to the surface, bringing with them some of the dissolved hydrogen. The degassing step reduces the occurrence of
hydrogen gas porosity. In the steel making process, this method is used very commonly for duplex steel and some high reactivity metals.
See also
*
Froth flotation, the use of gas bubbles to separate or extract hydrophobic liquids and/or solids from hydrophilic liquids
References
{{Reflist
Laboratory techniques
Metallurgy