In recent years, due to its excellent performance in adsorbing heavy metals in sewage, biochar has attracted more and more attention. This paper studied the adsorption properties and mechanism of pine wood and soybean straw, which were produced under different pyrolysis temperature of 400, 600, and 800 °C. The biochar was characterized by scanning electron microscopy, elemental composition analysis and BET surface analyzer. Six types of biochar were used for adsorption experiments with solutions containing Pb2+, respectively. The influences of pyrolysis temperature, solution pH on the adsorption performance of biochar Pb2+ were discussed. The results show that, the specific surface area of pine wood biochar is significantly higher than that of soybean straw biochar. The internal functional groups of soybean straw biochar are abundant. With the increase of pyrolysis temperature, the C content, specific surface area, and the amount of alkali metal all rise. Meanwhile, the adsorption capacity of biochar to Pb2+ in the solution all increase. Under the same pyrolysis temperature, the adsorption capacity of soybean straw biochar is stronger than that of pine biochar. As pH increases, the adsorption capacity of pine wood and soybean straw biochar would be stronger, especially for pine wood biochar.
Keywords Biochar, Pyrolysis temperature, Cation exchange