| 生物炭负载纳米零价铁对污染土壤中铜钴镍铬的协同去除 |
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| 引用本文： | 席冬冬,李晓敏,熊子璇,姜智,张晓明,杨卫春.生物炭负载纳米零价铁对污染土壤中铜钴镍铬的协同去除[J].环境工程,2020,38(6):58-66. |
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| 作者姓名： | 席冬冬 李晓敏 熊子璇 姜智 张晓明 杨卫春 |
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| 作者单位： | 中南大学 冶金与环境学院, 长沙 410006 |
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| 摘 要： | 合成了一种低成本、高效生物炭负载纳米零价铁的复合材料(ZVI-SM)并应用于铜、钴、镍、铬污染土壤的修复。采用X射线衍射(XRD)、X射线光电子能谱(XPS)和金属吸附实验等方法,考察了不同碳化温度下制备的生物炭前驱体和生物炭复合材料对复合重金属污染修复的影响及去除作用机制。其中,吸附-还原后形成的FeCr2O4极大地降低了铬的毒性,同时提高了铜、钴、镍的去除率。Fe0的引入既提高了生物炭对重金属的吸附量,又解决了Cr(Ⅵ)毒性的问题;XPS的结果进一步阐明了生物炭可以作为电子传递介质,通过表面官能团得失电子与Fe0间形成强相互作用,增强了复合材料对多重金属离子的去除效果。除ZVI-SM500外,ZVI-SM100、300、400、700 4种材料对于铜、钴、镍、铬的去除率要远高于商用纳米Fe0和单纯的生物炭材料,表现为对铬和铜有较强的亲和力和反应性,均能在5 min内完全去除铜和铬,钴和镍也能在180 min内达到80%以上的去除率。在反应过程中存在显著的离子竞争效应:铬≥铜>钴>镍,这与金属离子的标准还原电位大小的趋势一致。土壤修复实验表明:ZNI-SM300用于污染土壤的修复,15 d后,Cr(Ⅵ)含量从480 mg/kg降至0.52 mg/kg,水溶态Cr总量从500 mg/kg降至1.2 mg/kg,两者的固定化效率均达到99%以上,并能达到完全去除水溶态的铜、钴、镍、Cr(Ⅵ)的效果。因此,以SM300为载体的纳米零价铁可作为复合重金属污染土壤修复的理想材料。
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| 关 键 词： | 生物炭 Fe0 六价铬 还原 重金属 协同去除 |
| 收稿时间： | 2020-03-24 |
SYNERGISTIC REMOVAL OF Cu,Co, Ni AND Cr FROM CONTAMINATED SOIL BY BIOCHAR-SUPPORTED NANOSCALE ZERO-VALENT IRON |
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| XI Dong-dong,LI Xiao-min,XIONG Zi-xuan,JIANG Zhi,ZHANG Xiao-ming,YANG Wei-chun.SYNERGISTIC REMOVAL OF Cu,Co, Ni AND Cr FROM CONTAMINATED SOIL BY BIOCHAR-SUPPORTED NANOSCALE ZERO-VALENT IRON[J].Environmental Engineering,2020,38(6):58-66. |
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| Authors: | XI Dong-dong LI Xiao-min XIONG Zi-xuan JIANG Zhi ZHANG Xiao-ming YANG Wei-chun |
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| Affiliation: | School of Metallurgy and Environment, Central South University, Changsha 410006, China |
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| Abstract: | In this study, a low-cost and highly efficient composite material (ZVI-SM) with nanoscale zero-valent iron loaded by biochar was synthesized and applied to the remediation of copper, cobalt, nickel and chromium contaminated soil. The effects of biochar precursors and biochar composites prepared at different carbonation temperatures on the remediation of heavy metal contamination, and their removal mechanisms were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and metal adsorption experiment. FeCr2O4 formed by adsorption and reduction greatly reduced the toxicity of chromium and improved the removal efficiency of copper, cobalt and nickel. The introduction of Fe0 not only increased the adsorption capacity of heavy metals to biochar, but also solved the problem of toxicity of Cr(Ⅵ). XPS further clarified that biochar could be used as the electron transfer medium; the strong interaction between the gain and loss electrons of the surface functional groups; Fe0 could enhance the removal effect of the composite material on multi-heavy metal ions; besides ZVI-SM500, the removal rates of rest of the four materials, ZVI-SM100, 300, 400, 700 for copper, cobalt, nickel, chromium were much higher than the commercial nanoscale Fe0 and single application of biological carbon materials; this kind of composite material (ZVI-SM) showed a strong affinity and reactivity to chromium and copper, and completely removed copper and chromium in 5 minutes. Cobalt and nickel could also achieve more than 80% removal rate in 180 minutes. There was a significant ion competition effect in the reaction process in the order of Cr≥Cu>Co>Ni, consistent with the trend of the standard reduction potential of metal ions. Soil remediation experiments showed that ZNI-SM300 for remediation of contaminated soil, after 15 days, the content of Cr(Ⅵ) decreased from 480 mg/kg to 0.52 mg/kg, and the total amount of water-soluble Cr decreased from 500 mg/kg to 1.2 mg/kg. The immobilization efficiency of both was more than 99%, while the total removal effect of water-soluble copper, cobalt, nickel and Cr(Ⅵ) was achieved. Therefore, the nanoscale zero-valent iron with SM300 as the carrier could be used as the ideal material for the remediation of soil contaminated by composite heavy metals. |
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