磷酸改性生物炭对土壤中Pb^(2+)和Cd^(2+)钝化特性

Passivation characteristic of Pb^(2+) and Cd^(2+) in soil by phosphoric acid modified biochar

为探究改性生物炭对于土壤重金属的钝化作用,用磷酸对600℃热解的小麦秸秆生物炭进行改性,通过培土钝化实验探究改性生物炭添加量对土壤pH、重金属赋存形态及弱酸可提取态的影响。研究表明,随着投放时间的增加,土壤逐渐呈现碱性。改性生物炭能够促进重金属离子由有效态向稳定态转化,且钝化效果与改性生物炭的添加量呈正相关。土壤中单一污染Pb^(2+)及Cd^(2+)的弱酸可提取态均随投放时间及生物炭添加量的增大而降低,其中前20 d的降低幅度最大。

In order to investigate the passivation of modified biochar on the heavy metal in soil, the wheat straw biochar pyrolyzed at 600 ℃ was modified by phosphoric acid.The soil preparation passivation experiment was carried out to explore the effects of modified biochar additions on soil pH,heavy metal occurrence forms, and the extractable state of weak acid were investigated.Result shows that the soil gradually became alkaline with the increase of adsorption time.Modified biochar was able to promote the conversion of heavy metals from effective state to stable state, and the passivation effect was positively correlated with the addition amount of modified biochar.The extractable states of Pb^(2+)and Cd^(2+)in single contaminated soil decreased with the increase of adsorption time and addition amount, in which the largest decrease range was occurred in the first 20 d.