| 许亚琼,王雪佳,李荣华,肖然,张增强.纳米零价铁改性生物炭对污染土壤中Cd稳定化效果及作用机制研究[J].农业环境科学学报,2022,41(11):2478-2487. |
| 纳米零价铁改性生物炭对污染土壤中Cd稳定化效果及作用机制研究 |
| Effects and mechanisms of nano zero-valent iron-modified biochar on Cd stabilization in contaminated soils |
| 投稿时间：2022-02-27 |
| DOI：10.11654/jaes.2022-0185 |
| 中文关键词: Cd 纳米零价铁改性生物炭（nZVI-BC） 污染土壤修复 稳定化机制 |
| 英文关键词: Cd nano zero-valent iron modified biochar（nZVI-BC） remediation of contaminated soil stabilizing mechanism |
| 基金项目:国家自然科学基金项目（41907120）；中央高校基本科研业务费（SWU020002） |
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| 中文摘要: |
| 为研究纳米零价铁改性生物炭（nZVI-BC）对土壤镉（Cd）的长效稳定机制，特别是生物炭（BC）老化过程中nZVI-BC与Cd的界面相互作用，本研究以玉米秸秆为原料制备了nZVI-BC，采用批吸附与养护试验相结合的方法并利用现代光谱分析手段探究了nZVI-BC对液相Cd （Ⅱ）的吸附和对土壤中Cd的稳定化效果与作用机制。结果表明： nZVI负载显著提高了生物炭对Cd （Ⅱ）的吸附能力，nZVI-BC对Cd （Ⅱ）的饱和吸附量是BC的4.3倍（125.5 mg·g-1 vs 23.61 mg·g-1）。nZVI-BC对Cd （Ⅱ）的吸附更符合伪二级动力学方程，吸附过程以化学吸附为主；其等温吸附更符合Langmuir模型，属于单层吸附。随着养护时间的增加，生物炭表面的Cd负载量逐渐增加，老化后BC表面形成的含氧官能团是Cd饱和吸附力增加的主要原因。相比而言，nZVI-BC上Cd的负载量呈先增加后逐渐降低的趋势。沉淀与表面络合是nZVI-BC固定土壤中Cd的主要机制，而Fe含量的降低和Fe的氧化则是导致其Cd固定量降低的主要原因。尽管如此，nZVI-BC对Cd的吸附仍保持在较高水平且远高于BC。综上所述，nZVI-BC可以作为一种能够适用于中度污染农田中Cd修复的高效稳定化材料。 |
| 英文摘要: |
| To study the long-term stabilization mechanisms of nano zero-valent iron-modified biochar（nZVI-BC）on soil Cd, especially the interfacial interaction between nZVI-BC and Cd during the aging process of biochar, the influence of nZVI-BC on Cd immobilization in neutral-alkaline soils was investigated using combined methods（including batch adsorption experiments and simulation trials） and characterized using novel spectrum analysis techniques. The results showed that the nZVI loading significantly improved the adsorption capacity of biochar for Cd（Ⅱ）, and the saturated adsorption capacity of nZVI-BC for Cd（Ⅱ）was 4.3 times higher than that of BC（125.5 mg·g-1 vs 23.61 mg·g-1）. The adsorption of Cd（Ⅱ）by nZVI-BC agreed with the Pseudo-second-order kinetic equation, and the adsorption process was mainly chemical adsorption. Its isothermal adsorption was more consistent with the Langmuir model, which belongs to monolayer adsorption. With the increase in culture time, the Cd loading on the surface of the biochar gradually increased, and the oxygen-containing functional groups formed on the BC surface after aging were the main reason for the increase in Cd saturation adsorption capacity. In contrast, the Cd load on the nZVI-BC first increased and then decreased gradually. Precipitation and surface complexation were the main mechanisms for nZVI-BC to fix Cd in the soil, and the reduction of Fe content and oxidation were the main reasons for the reduction of Cd fixation. However, the adsorption of Cd by nZVI-BC remained at a high level and was much higher than that of BC. In conclusion, nZVI-BC can be used as a highly effective stabilizing material for Cd remediation in moderately polluted farmlands. |
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