Chemical Engineering Communications
Gas-liquid mass transfer in an aerated stirred tank containing two liquid phases (a heptane/dodecane solution dispersed in water) was investigated by measuring the saturation of heptane in the exit gas. Heptane saturation as a function of organic phase composition in a gas-liquid-liquid system supports the view that the organic phase spreading coefficient, S, is an extremely important factor in the mass transfer rate in gas-liquid-liquid systems. When the spreading coefficient of the organic solution changes from negative to positive, the outlet gas becomes saturated, corresponding to a severalfold increase in mass transfer coefficient. This clearly reinforces the hypothesis that the mass transfer pathways between organic and gas phase change depending on the sign of S, leading to a different structure of mass transfer resistances: when S>0, there is direct contact between gas and organic phase; when S<0, there is not. At S close to 0, the situation is intermediate, there being some evidence that turbulent kinetic energy may play a role in determining the amount of direct contact between gas and organic phase. © Taylor & Francis Group, LLC.
Year of publication: 2010