A model to describe the retention of solute could reduce the need of repeated testing for each new application and be useful for understanding the separation mechanisms of nanofiltration.For uncharged solutes

the separation is achieved by sieving effect

and steric-hindrance pore(SHP)model is appropriate.But obtaining membrane pore radius (rp) from SHP model needs permeation experiments of uncharged solutes

which are difficult and burdensome.On the other hand

the molecular weight cut-off (MWC) is a concept that is strongly established in membrane field.By introducing the MWC in SHP model

the existing information about the membrane can be used

which can simplify the implementation of model.In this paper

the correlation between the Stokes radius (rs) and molecular weight (MW) was established.[HJ*4/9]Then based on the assumption that the membrane pore radius equals the Stokes radius of uncharged solute with molecular weight equal to MWC

rp and rs can be expressed as functions of MWC and MW respectively.On the basis of SHP model and Spiegler-Kedem model

a model named as MWC parameters steric-hindrance pore model (MWC-SHP) was established.Permeation experiments of aqueous solution of glucose and sucrose with spiral membrane (NF270) were conducted and the structural parameters (rp and the ratio of membrane porosity to membrane thickness) were estimated by using MWC-SHP model and SHP model respectively.The results estimated from MWC-SHP model were in agreement with SHP model.Moreover

rejection prediction of uncharged solutes by nanofiltration with MWC-SHP model was in agreement with experimental data

which showed MWC-SHP model could be applicable to the evaluation of the structure of nanofiltration membrane and rejection prediction of uncharged solutes.