Transport of the substance through thin membranes with narrow pores after the preceding stage of surface diffusion

A model of the substance transport through thin membranes is discussed. Existence of a step of the surface diffusion of permeable particles is assumed preceding its entrance into membrane channel. An expression is given for the stationary flow, which has earlier been obtained for other transport models. It is shown that the permeant affinity to the membrane surface is the main condition for the validity of the scheme in question.