The authors regret to inform that an error occurred in Eq. (2), Eq. (7) as well as Figs. 3, 6 and 7 of the article with the aforementioned title. In the equations, the mean real liquid velocity (v_L) should be applied instead of the fluid superficial velocity (u_L): [Formula presented] [Formula presented] The equations are related to the fitted curves based on the axial dispersion model (Fig. 3) and to the extracted axial dispersion coefficients (Figs. 6 and 7). The correct figures are now presented via this corrigendum. It is worth mentioning that none of these mistakes affects the originality of the article's text and the presented results. The authors would like to apologise for any inconvenience caused.