The Mechanism And Enhancement Of Gas-liquid Interfacial Mass Transfer

Gas-liquid mass transfer is often encountered in chemical engineering process. However, up to now, most researches in the field are based on macro phenomenon. The classic mass transfer theories and hypothesis are developed on the basis of some empirical and semi-empirical correlations. Therefore, the inherent mass transfer characteristic and mechanism have not yet been well known. It is of virtual significance to deeply investigate the micro mechanism of interfacial mass transfer and develop accuracy non-linear mass transfer pattern taking into account the interfacial non-equilibrium principle.The mass transfer process of methanol-CO2, ethanol-CO2, n-propanol- CO2, n-butanol-CO2 and influence of various concentrations sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), cetyl trimethyl ammonium bromide (CTAB), polyacrylic acid (PAA) on mass transfer at different body velocities were studied respectively using micro holographic interferometer, and the concentration distribution near the interface, interfacial concentration and concentration boundary layer thickness on liquid side were determined.On the basis of molecule thermodynamics, combining the general chemical potential driving force equation of mass transfer flux, the non-equilibrium principle at the interface was proposed and a concentration correlation between two phases at the interface is derived and solved under both quiescent and mobile conditions in the absorption processes of bubble,respectively, good agreements have been achieved between the calculated data and experimental data. For the absorption process of gaseous species into stationary droplets, equilibrium relation and non-equilibrium relations at the interface were used to analyze and predict the absorption time for a physical absorption at a relatively low solubility of gas, and the concentration distribution within the droplet at different times is solved. In addition, based on convection-diffusion equation, considering the effect of interfacial resistance on mass transfer, concentration field near the interface around bubble in liquid phase was solved, and the results were at good agreement with the experimental data.The enhancement of gas-liquid mass transfer is very important in the intensification of chemical engineering process. CO₂ absorption in the slurries containing different concentration activated carbon particles and water at various stirrer speeds were studied experimentally in a thermostatic reactor, and the enhancement factors were determined. A quantitative model for predicting enhancement factor was proposed based on film model and non-equilibrium principle, which could well explain the effect of particles concentration and stirring intensity on enhancement factor, and the prediction value of present model are at considerable agreement with experimental data.