Mathematical modeling for nanofiltration of ionic liquids (ILs) solutions could assist to understand transfer mechanism and predict experimental values. In this work, modeling by solution-diffusion model for nanofiltration of long-alkyl-chain ILs aqueous solutions was proposed. Molecular simulations were performed to validate the existence of ion cluster in long-alkyl-chain Its aqueous solution. Based on the results of simulations, parameters used in the solution-diffusion model were modified, such as concentration of ILs and diameter of ion cluster. The modeling process was developed for three long-alkyl-chain ILs aqueous solutions with different concentrations (1-alkyl-3-methylimidazolium chloride: [C(6)mim]Cl, [C(8)mim]Cl, [C(10)mim]Cl). The calculated values obtained from modified solution-diffusion model could well match the experimental values. (C) 2020, Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.