Review of gas–liquid mass transfer enhancement by nanoparticles from macro to microscopic

Gas–liquid mass transfer is an extremely common process in the chemical industry and enhancing this process can help achieve high efficiency and low energy consumption. The addition of nanoparticles in the liquid phase is an important method for enhancing such transfers. In this paper, the preparation methods of nanofluids are briefly described and the parameters associated with nanofluid transport, such as mass-transfer coefficient, liquid volumetric mass-transfer coefficient, mass transfer interface area, and gas holdup, are introduced. Then, the latest experiments and mechanisms for the effect of nanofluids on the gas–liquid mass transfer process are reviewed from the viewpoint of transport parameters. The reasons for the enhancement of gas–liquid mass transfer by nanofluids are given: shuttle effect, mixing of the gas–liquid boundary layer, and inhibition of bubble coalescence. Finally, the problems existing in current research are assessed and, toward enhancing gas–liquid mass transfer using nanoparticles, future research directions are proffered.