A diffusion type of model is proposed for modeling of the scale effect in column apparatuses. The mass transfer with chemical reaction model is investigated. The influence of the radial non-uniformity of the velocity distribution on the mass transfer efficiency, column height and scale-up is obtained. The effect of Fourier and Damkohler numbers on the process efficiency is analyzed. The present data show that mass transfer efficiency in column apparatuses decreases with the column diameter increase. (C) 2008 Elsevier Ltd. All rights reserved.