The process of absorption of CO2 in ethanol was studied in a transparent channel under various flow conditions of a co-current gas-liquid flow

and the concentration and velocity distributions in the liquid in the vicinity of gas-liquid interface were measured with holographic interferometry and laser Doppler anemometer respectively.An exponential increase of concentration within the boundary layer could be observed.The concentration gradient increased with increasing velocities of liquid and/or gas and the velocity boundary layer was thicker than that of concentration.A mass balance based approach was used for estimating liquid mass transfer coefficients

and average mass transfer coefficients in the liquid phase were obtained for different flow conditions.The results were compared to those calculated with the Whiteman’s two-film model.