Mass transfer processes were evaluated in an artificial, non-uniform porous medium with a power law distribution of diffusion rate coefficients obtained from physical characterization of solute and porous medium. Breakthrough curves of several pulse experiments conducted at different velocities were compared (1) to analytical expressions for concentrations at mass transfer dominated times, and (2) to simulated breakthrough curves of a 1-D transport model. After correcting diffusion rate coefficients for irregularly shaped particles both analytical and numerical model were able to accurately represent breakthrough curves and latetime concentrations. The main conclusions of this study are the following. First, by connecting normalized breakthrough curves of experiments conducted at different velocities it is possible to obtain the derivative of the residence time distribution of the immobile domain, which completely describes the mass transfer behavior of the column. From the derivative of the residence time distribution, the scaling behavior of mass transfer dominated breakthrough curves can be predicted. Second, in presence of multiple rates of mass transfer the use of a single rate model may lead to velocity-dependent mass transfer rate coefficients. Third, a power law distribution of diffusion rate coefficients is directly related to the late-time slope of breakthrough curves, and, if pore diffusivity is constant for all particles of the porous medium, also to the distribution of grain sizes