Barbotage is a term derived from French and it means the process of gas flow in the form of bubbles through the liquid layer. It is used to increase the surface contact of liquid with gas and to mix liquids or suspensions.
Barbotage - or barboting - is a term referring to one of many processes in the chemical industry. In these processes, several phases, i.e. gas, liquid and solid, come into contact in one apparatus. Barbotage accelerates the mixing of liquid and ozone, and the barboter used for this process is also called a bubbler. Barbotage is the way to ozonating liquids. Barboter is a cable section with openings or a bell with cutouts that release gas bubbles.
What is the barbotage of gas in the liquid?
Barbotage of gas (ozone) in a liquid is the basic way of contacting the liquid and gas phases. Individual bubbles with specific diameters arise when the gas exits the nozzle immersed in the liquid. Bubbles are affected by buoyancy force that lifts them up. The greater is the volume increase, the more bubbles appear. As the bubbles flow up, the distances between them decrease. They can move in two ways, and therefore two forms are distinguished:
• free barbotage - when individual bubbles flow separately – we use that method to ozone oils
• chain barbotage - when the bubbles are arranged in a chain (this occurs due to exceeding the critical volume value of the gas flow rate, which is determined by comparing bubble diameters in both types of barbotage).
Bubbles can move in a laminar or turbulent motion.
3 zones are distinguished during barbotage:
The key issue in the barbotage is to estimate the value of the interfacial area in the apparatus. Appropriate calculations allow to obtain two important values, i.e. the size of the interfacial area per one bubbler hole and the height column of the liquid.
Barbotage in absorption and rectification
Barbotage is used in absorption and rectification. Absorption is the process of penetration of one substance into another, resulting in any continuous phase. It is very common in nature - e.g. breathing. In addition, this phenomenon is used on an industrial scale. Absorption is frequently referred to, e.g. in the context of environmental issues. Today's companies are under intense pressure to conduct operations based on a specific environmental strategy to reduce pollution. Absorption allows purification of gases from harmful components such as sulfur oxides.
The next area of barbotage application is rectification - i.e. fractional distillation or fractionated distillation. It is carried out on a large scale in industry, e.g. petrochemicals or spirits. This is usually made in specially designed rectification columns, zone columns or columns with a cooling or heating jacket are less frequently used. There is a miniaturized version of such columns - for example in chemical laboratories.
Barbotage and biotechnologies
Barbotage process is also used in many other areas, like biotechnologies necessary, e.g. in the modern veterinary or pharmaceutical industry. Different types of bioreactors (fermenters) are used in which microbes and plant and animal cells are grown. Various types of bioreactors include, among others, barbotage bioreactors. Their shape resembles a cylindrical column and the air is supplied from below. The appropriate level of oxygenation of the reaction environment is extremely important in the aerobic biodegradation process carried out here, hence a sufficient number of small air bubbles is necessary in barbotage bioreactors. The most well-known examples of the use of this type of bioreactors include biological wastewater treatment plants whose construction corresponds to current ecological trends aimed at caring for the natural environment.
Written by Jakub Hubert Luft
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