THE IMPORTANCE OF AXIAL DISPERSION IN LIQUID-PHASE FIXED-BED ADSORPTION OPERATIONS

Methods are given for computing concentration profiles and breakthrough curves in fixed bed adsorbers for Freundlich and Langmuir equilibria, for cases of zero and non-zero axial dispersion. The methods are limited to situations in which either particle diffusion or external film diffusion is the dominant mass transfer process. By considering parameter values typical of liquid phase systems, it is shown that the values of parameters representing the ratios of mass transfer resistances to the axial dispersion coefficient serve as indicators of whether or not axial dispersion effects are important. Axial dispersion can be significant whenever the particle size and/or flow rate is substantially smaller than usual.