Adsorption in membranes with polydispersed pores gives a dispersed breakthrough curve even when mass transfer is so fast that it reaches saturation. Such a breakthrough is due to unequal flows in unequally sized pores. A theory of polydispersed pores can predict the breakthrough curves for the removal of lead ions from model solutions if the pore-size distribution is known. Such predictions are in better agreement for lead adsorption than predictions based on mass transfer. The results suggest ways in which More effective membrane chromatography can be achieved. (c) 2015 American Institute of Chemical Engineers