Dear Colleagues,

Gas–liquid contactors are one of the most important units in the chemical industry. In particular, bubble column reactors are widely used in absorption, oxidation, chlorination, oxichlorination, carboxylation, carbonylation, sulfonation, hydrogenation, polymerization, alkylation, esterification, etc. Most of these processes are accompanied by a slow chemical reaction. Fischer–Tropsch, methanol and dimethyl ether syntheses, and aerobic fermentation and biological wastewater treatment could also be implemented in effective gas–liquid contactors. Most of the gas–liquid contactors provide excellent mixing and mass and heat transfer characteristics.

The hydrodynamic behavior of the gas–liquid reactors is very complex, irrespective of their simple construction. When a chemical reaction takes place, several dead zones and many local inhomogeneities are formed. This leads to different local liquid mixing and volumetric liquid-phase mass transfer coefficients across the gas–liquid reactor. The radial profiles of both the gas holdups and liquid velocities are also different. These phenomena depend on the prevailing hydrodynamic regime. That is why new methods for reliable flow regime identification should be developed. In this Special Issue, all these important topics will be covered. Both new theoretical approaches and experimental techniques for better understanding of the hydrodynamic and mass transfer behavior of various gas–liquid contactors (bubble columns, agitated vessels, airlift reactors, etc.) will be presented.

Prof. Dr. Stoyan Nedeltchev
Guest Editor

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• hydrodynamics
• mixing
• gas–liquid mass transfer
• bubble columns
• agitated vessels
• airlift reactors
• new measurement techniques
• reactor modelling