Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, PR China.
J Hazard Mater. 2019 Jul 5;373:250-257. doi: 10.1016/j.jhazmat.2019.03.076. Epub 2019 Mar 19.
Biochar system technology has been proved as a sustainable remediation method for metal contaminated soils. However, little attention has been paid to the interaction between biochar and oxide minerals and their influence on metal immobilization in soils. In this study, batch-type Zn sorption experiments were conducted using the mixture of γ-AlO and rice straw biochar as a model binary geosorbent systems. In addition, advanced spectroscopic technics such as EXAFS, FTIR and XRD were performed to reveal the mechanism. EXAFS spectroscopy revealed that 62% of Zn existed as Zn-Al layered double hydroxide (LDH) on γ-AlO at pH 7.5 (for 2 mM Zn loading) within 24 h, which was 19% in the mixture. The Zn in biochar samples mainly existed as Zn-OM (53%-76%) and ZnSiO (21%-47%), while the proportion of ZnSiO (0-6%) was negligible compared with Zn-Al silicate (26-48%) in the mixtures. The overall findings confirmed that Al released from γ-AlO was sorbed in parallel with Zn on biochar to form Zn-Al silicate, rather than Zn-Al LDH on the γ-AlO surface. These results unveiled the dynamic interactions between amended biochar and soil oxide minerals which can significantly affect the immobilization pathways of metals in contaminated soils.
生物炭系统技术已被证明是一种用于修复受金属污染土壤的可持续方法。然而，人们对生物炭与氧化物矿物之间的相互作用及其对土壤中金属固定的影响关注甚少。在本研究中，使用γ-AlO 和稻草生物炭混合物作为模型二元地质吸附剂系统进行了批式 Zn 吸附实验。此外，还采用了 EXAFS、FTIR 和 XRD 等先进的光谱技术来揭示其机制。EXAFS 光谱表明，在 pH 7.5（2 mM Zn 负载量）下，24 小时内，62%的 Zn 以 Zn-Al 层状双氢氧化物（LDH）的形式存在于 γ-AlO 中，而混合物中的含量为 19%。生物炭样品中的 Zn 主要以 Zn-OM（53%-76%）和 ZnSiO（21%-47%）的形式存在，而混合物中 ZnSiO（0-6%）的比例与 Zn-Al 硅酸盐（26-48%）相比可以忽略不计。总的研究结果证实，从 γ-AlO 释放的 Al 与生物炭上的 Zn 平行吸附，形成 Zn-Al 硅酸盐，而不是 γ-AlO 表面上的 Zn-Al LDH。这些结果揭示了改性生物炭与土壤氧化物矿物之间的动态相互作用，这可能会显著影响污染土壤中金属的固定途径。
