The Beijing Key Laboratory of New Technology in Agricultural Application, Department of Agricultural Resource and Environment, Beijing University of Agriculture, Beinong Road 7, Huilongguan, Changping District, Beijing, 102206, China.
The Beijing Key Laboratory of New Technology in Agricultural Application, Department of Agricultural Resource and Environment, Beijing University of Agriculture, Beinong Road 7, Huilongguan, Changping District, Beijing, 102206, China; Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, No.12 Zhongguancun South St., Haidian District, Beijing, 100081, China.
J Environ Manage. 2022 Jun 15;312:114903. doi: 10.1016/j.jenvman.2022.114903. Epub 2022 Mar 18.
The performances of passivation materials mitigating Cadmium (Cd) bioavailability considerably vary with the pH condition of Cd-contaminated soils. However, less information was available for the method of improving Cd passivation efficiency taking into account the pH of the targeted soil. Furthermore, the underlying mechanism of Cd availability mitigation in soils with different pH has not been clearly explored. In this study, cotton straw biochar (CSB) and its modified products using NaOH (CSB-NaOH) were prepared and applied in two kinds of Cd-contaminated soils with different pH. It was found that CSB-NaOH was more effective than CSB in regulating the Cd bioavailability in the acid soil, while the opposite tendency was observed in alkaline soil. The difference of the Cd passivation efficiency is correlated with contributions of various Cd-biochar binding mechanisms, which cation exchange mechanism is largely eliminated for CSB-NaOH. The interaction of Cd with CSB/CSB-NaOH was further evidenced through characterization results of Scan Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR) and X-ray Photoelectron spectroscopy (XPS). Characterization results proved that carboxyl, hydroxyl and ethyl groups were the key functional groups involved in Cd passivation. XPS results showed that Cd binding methods varied between CSB and CSB-NaOH, which Cd and Cd-O were the main form of Cd binding to CSB while Cd-O was the main form on CSB-NaOH. In this work, it was demonstrated that in acid soil, pH change caused by biochar plays a more significant role in controlling the Cd bioavailability, while in alkaline soil, the strength of the Cd-biochar interaction is more decisive for the Cd passivation efficiency. This work provides information on how to select the suitable passivator to decrease the Cd bioavailability in terms of different soil pH and property.
钝化材料对减轻土壤中镉生物有效性的性能受镉污染土壤 pH 值条件的影响较大。然而，考虑到目标土壤的 pH 值，提高镉钝化效率的方法信息较少。此外，不同 pH 值土壤中镉有效性降低的潜在机制尚未得到明确探讨。本研究制备了棉秆生物炭（CSB）及其用 NaOH 改性的产物（CSB-NaOH），并将其应用于两种 pH 值不同的镉污染土壤。结果表明，CSB-NaOH 比 CSB 更能有效调节酸性土壤中镉的生物有效性，而在碱性土壤中则呈现相反的趋势。钝化效率的差异与各种镉-生物炭结合机制的贡献有关，其中 CSB-NaOH 中阳离子交换机制基本消除。通过扫描电子显微镜（SEM）、X 射线衍射（XRD）、傅里叶变换红外光谱（FTIR）和 X 射线光电子能谱（XPS）的表征结果进一步证实了 CSB/CSB-NaOH 与 Cd 的相互作用。表征结果证明，羧基、羟基和乙基是参与 Cd 钝化的关键功能基团。XPS 结果表明，CSB 和 CSB-NaOH 之间 Cd 的结合方式不同，CSB 上主要以 Cd 和 Cd-O 的形式结合 Cd，而 CSB-NaOH 上主要以 Cd-O 的形式结合 Cd。在这项工作中，证明了在酸性土壤中，生物炭引起的 pH 值变化在控制镉生物有效性方面起着更重要的作用，而在碱性土壤中，Cd-生物炭相互作用的强度对 Cd 钝化效率的决定作用更大。本研究为如何根据不同土壤 pH 值和性质选择合适的钝化剂来降低镉生物有效性提供了信息。
