Effects of surface roughness on self- and transport diffusion in porous media in the Knudsen regime - art. no. 125505

The effect of surface roughness on Knudsen diffusion in nanoporous media is investigated by means of dynamic Monte Carlo simulations in three-dimensio nal rough fractal pores. These simulations yield new insight and explain a number of apparent inconsistencies by revealing a striking difference betwe en the roughness dependence of transport diffusion and gradientless (self- or tracer) diffusion. Both analytical and simulation results show a signifi cant roughness dependence of self-diffusion in the Knudsen regime. Transpor t diffusion, on the other hand, is roughness independent, as the fluxes do not depend on the detailed residence time and molecular trajectories.