热解温度对秸秆生物炭钝化重金属污染土壤影响分析

Effect of Pyrolysis Temperature on Heavy Metal Contaminated Soil Passed by Straw Biochar

为了探究热解温度对以黄豆秸秆制备生物炭对土壤重金属Pb及Cd的吸附及钝化性能,以黄豆秸秆为原材料,在300、500、700℃热解温度下制备生物炭,并探究其对土壤重金属铅锌的钝化作用。实验结果表明随热解温度升高,生物炭中碳含量呈现上升趋势,且pH由8.95升高至10.23,灰分的含量却由34.5%下降至28.6%。热解温度能对生物炭吸附重金属Pb及Cd产生影响,并且热解温度升高,重金属吸附量呈现上升趋势,并且当热解温度为700℃时,生物炭对Pb及Cd的吸附量分别为1.2、26.8 mg/g。进一步探究表明热解温度能够提高生物炭对Pb及Cd的钝化性能,机制研究表明生物炭能够提高土壤中pH,并且热解温度升高提高了残渣态Pb及Cd的含量而降低酸可提取态Pb及Cd的含量。

In order to investigate the adsorption and passivation of heavy metals Pb and Cd in soil by biochar prepared from soybean straw under pyrolysis temperature,biochar was prepared from soybean straw at 300℃,500℃and 700℃,and its passivation effect on heavy metals Pb and Zn in soil was investigated.The experimental results show that with the increase of pyrolysis temperature,the C content in biochar increases,and the pH value increases from 8.95 to 10.23,while the ash content decreases from 34.5%to 28.6%.Pyrolysis temperature can affect the adsorption of heavy metals Pb and Cd by biochar.With the increase of pyrolysis temperature,the adsorption of heavy metals shows an upward trend.When pyrolysis temperature is 700℃,the adsorption of Pb and Cd by biochar is 1.2 mg/g and 26.8 mg/g,respectively.Further research shows that the pyrolysis temperature improves the passivation of Pb and Cd by biochar.The mechanism study shows that biochar could improve the pH of soil,and the pyrolysis temperature increases the content of residual Pb and Cd,while decrease the content of acid extractable Pb and Cd.