Abstract: [Objective] The present work is for studying the preparation of adsorbent with modified tannin to provide technical basis for the application of natural tannin in the treatment of heavy metal ions pollution.[Method]With bayberry tannin (BT) and acacia mangium tannin (AMT) as raw material, the formaldehyde reacted with condensed tannin to form hydroxyl methylated tannin under alkaline conditions. Then the amide group of polyacrylamide (PAM), as nucleophilic reagent, reacted with hydroxyl methylated tannin to prepare bayberry tannin adsorbent PBT and acacia mangium tannin absorbent PAMT, respectively. The physicochemical properties of tannin before and after modification and adsorption of Pb(Ⅱ) and Cu(Ⅱ) were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and infrared spectroscopy(FTIR). The adsorption performances of Pb(Ⅱ) and Cu(Ⅱ) were also investigated.[Result]The results showed that the crosslinking reaction was occurred with the modification of BT and AMT, leading to increased particle size, but no significant change in the microscopic surface. The maximum adsorption capacities of 49.75 and 142.86 mg·g^-1 were obtained for Cu(Ⅱ)and Pb(Ⅱ)on PBT respectively, and the maximum adsorption capacities of 34.16 and 115.61 mg·g^-1 were obtained for Cu(Ⅱ)and Pb(Ⅱ)on PAMT, respectively.[Conclusion]The PAM modified tannin adsorbents have good stability and stronger adsorption capacity. The equilibrium adsorption capacities of Pb (Ⅱ) and Cu (Ⅱ) were higher than those of BT, AMT and PAM, indicating that the PAM modified biomass adsorbent has bright prospect.

Key words: tannin, PAM, PBT and PAMT adsorbents, Pb(Ⅱ)and Cu(Ⅱ), adsorption capacity