Abstract: Biomass coke adsorbent was prepared from biomass waste (rice husk, orange peel and walnut shell), and the biomass coke was modified by steam, H₃PO₄ or H₂O₂ to enhance its adsorption performance of benzene. The factors affecting coke yield and adsorption performance of biomass coke were studied. The results showed that the coke yield of three kinds of biomass was gradually decreased with the increase of pyrolysis temperature, and the coke yield of rice husk was significantly higher than that of walnut shell and orange pee. There are C—H bonds on the surface of the three biomass coke, a large number of C—O bonds on the surface of rice husk coke, and aromatic cyanogens containing C≡N bonds on the surface of orange peel coke. Among the three kinds of original biomass coke, walnut shell coke had higher benzene adsorption efficiency, and rice shell coke was relatively poor. After steam activation and pore expansion, the benzene removal rate of rice shell coke could be still maintained at about 85% for 60 min, and the benzene removal efficiency of H₃PO₄ modified rice shell coke also reached above 80%, while the benzene adsorption performance of H₂O₂ modified rice shell coke had not changed significantly.

Key words: biomass coke, rice husk coke, walnut shell coke, orange peel coke, steam activation, phosphoric acid modification