Direct determination of concentration-dependent diffusion coefficient in polymeric membranes based on the Frisch method

► A novel algorithm is presented for direct determination of diffusion coefficient. ► It applies for gas permeation process through the nonporous polymeric membranes. ► Succeeding time lag method it reaches to precise diffusivities using Frisch method. ► A mathematical model developed and solved for the concentration dependent system. ► Simulation results are in reasonable conformity with experimental data.