All reagents employed in these experiments were of analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd., China. All glasswares were rinsed with deionized water three times prior to their use. EDTA, dimethyl sulfoxide (DMSO) and SOCl2 were used in the chemical modification of the biomass. Stock solution of 1000 mg L−1 of Pb(II) was prepared by dissolving a desired amount of Pb(NO3)2 in deionized water and making the volume up to 1000 mL in a brown volumetric flask. A series of work solutions with the concentrations ranging from 20 to 600 mg L−1 of Pb (II) were prepared by appropriate dilution of the stock solution immediately prior to their use.