College of Resources and Environment, Jilin Agricultural University, Changchun, 130118, China.
Institute of Agricultural Resources and Environment, Jilin Academy of Agricultural Sciences (Northeast Agricultural Research Center of China), Changchun, 130033, China.
Sci Rep. 2020 Jun 1;10(1):8831. doi: 10.1038/s41598-020-65814-3.
In order to clarify the mechanism and effect of bentonite-supported nanoscale zero-valent iron (nZVI@Bent) on Cr(VI) removal in soil suspended liquid, nZVI@Bent was prepared by liquid-phase reduction method in this research. A number of factors, including the mass ratio of Fe to bentonite during preparation of nZVI@Bent, nZVI@Bent dosage, soil suspended liquid pH value and reaction temperature were assessed to determine their impact on the reduction of Cr(VI) in soil suspended liquid. The nZVI@Bent was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to analyze the mechanism of removal of Cr(VI) from the soil. The results showed that the temperature of soil suspended liquid had a significant effect on the removal efficiency. Calculated by the Arrhenius formula, nZVI@Bent removes Cr(VI) from the soil suspended liquid as an endothermic reaction with a reaction activation energy of 47.02 kJ/mol, showed that the reaction occurred easily. The removal of mechanism Cr(VI) from the soil by nZVI@Bent included adsorption and reduction, moreover, the reduction process can be divided into direct reduction and indirect reduction. According to XPS spectrogram analysis, the content of Cr(III) in the reaction product was 2.1 times of Cr(VI), indicated that the reduction effect was greater than the adsorption effect in the process of Cr(VI) removal. The experiment proved that nZVI@Bent can effectively remove Cr(VI) from soil suspension, and can provide technical support for repairing Cr(VI)-polluted paddy fields.
为了阐明膨润土负载纳米零价铁（nZVI@Bent）在土壤悬液中去除 Cr(VI)的机制和效果，本研究采用液相还原法制备了 nZVI@Bent。考察了制备 nZVI@Bent 过程中 Fe 与膨润土的质量比、nZVI@Bent 用量、土壤悬液 pH 值和反应温度等因素对土壤悬液中 Cr(VI)还原的影响。通过扫描电子显微镜（SEM）、X 射线衍射（XRD）和 X 射线光电子能谱（XPS）对 nZVI@Bent 进行了表征，分析了去除土壤中 Cr(VI)的机理。结果表明，土壤悬液温度对去除效率有显著影响。通过 Arrhenius 公式计算，nZVI@Bent 从土壤悬液中去除 Cr(VI)是一个吸热反应，反应活化能为 47.02 kJ/mol，表明反应容易发生。nZVI@Bent 从土壤中去除 Cr(VI)的机理包括吸附和还原，而且还原过程可以分为直接还原和间接还原。根据 XPS 图谱分析，反应产物中 Cr(III)的含量是 Cr(VI)的 2.1 倍，表明在去除 Cr(VI)的过程中还原作用大于吸附作用。实验证明，nZVI@Bent 能有效去除土壤悬液中的 Cr(VI)，可为修复 Cr(VI)污染稻田提供技术支持。
