  The interphase mass transfer plays a critical role in determining the height
of packed column used in the absorption process. In a recent experiment (Song
D. Ind. Eng. Chem. Res. 2018, 57, 718), the direct impact of viscosity
($\mu_L$) on the physical mass transfer coefficient ($k_L$) was observed to be
higher in a packed column as compared to the wetted wall column. We offer a
plausible mechanism involving the wavy film and eddy enhanced mass transfer in
a packed column to explain the underlying physics via analytical and numerical
studies. The analytically derived mass transfer coefficient matches well with
experimental observation in a packed column. The countercurrent flow
simulations in a packed column with both uniform and wavy films also confirm
this behavior. The predicted $k_L$ shows steep variation with $\mu_L$ for a
wavy film than a uniform film and further confirms the proposed theory. A
similar relation ($k_L \propto \mu_L^{-0.38}$) for a wavy film is also observed
in theoretical, experimental, and numerical studies.
