A kind of polyimide nanofiltration membrane made in our laboratory was grafting-modified to enhance its separation performance in the recovery process of diesel deacidfying solvent. The relationship between the reaction time,the kind of solvent,the kind and concentration of monomer and the grafting rate was investigated. The separation performance of membranes before and after grafting,at different grafting rate was measured. The results indicate the desired grafting rate of membrane can be obtained by adop...