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第一作者：Siqi Wen
通讯作者：薛文静 副教授
通讯单位：扬州大学环境科学与工程学院
DOI：10.1016/j.cej.2024.155676
近年来，电镀和采矿等工业活动导致铅（Pb）流入河流并在沉积物中过度富集，对水生生物构成潜在风险。基于此，本研究通过硫化改性和凹凸棒土（ATP）负载制备了凹凸棒土负载硫化纳米零价铁 (S-nZVI@ATP)，并首次应用于Pb污染沉积物的修复。全面研究了S-nZVI@ATP对Pb污染沉积物的固定化作用及机理，以及修复过程中微环境的变化。表征分析表明，S-nZVI均匀负载于ATP表面，并成功加载了ATP的特征官能团Al/Mg-OH和Si-O。培养实验表明，S-nZVI@ATP显著降低了沉积物中Pb的有效性和浸出毒性，其固定化效率分别高达94.08%和73.15% (P < 0.05)，同时促进了酸溶性Pb向残渣态的转化。这一现象说明S-nZVI@ATP在固定Pb方面表现出优异的性能。沉积物pH升高、Eh降低有利于Pb的固定化。S-nZVI@ATP的加入改变了沉积物细菌群落的结构和组成，以变形菌门、厚壁菌门和拟杆菌门为优势门。除蔗糖酶外，脲酶和过氧化氢酶活性分别提高了1.23倍和2.48倍。相关性分析显示pH、Eh、变形菌和厚壁菌在沉积物中固定铅的重要性。反应后材料的表征表明S-nZVI@ATP对沉积物中Pb的固定作用机制主要有吸附、络合、离子交换、静电吸引、还原和沉淀作用。
Fig. 1. SEM of ATP (a), S-nZVI (b), and S-nZVI@ATP (c); TEM of S-nZVI (d), and S-nZVI@ATP (e); EDS image (f) and mapping (g) of S-nZVI@ATP.Fig. 2. XRD spectra (a) and FTIR spectra (b) of ATP, S-nZVI, and S-nZVI@ATP; XPS spectra of S-nZVI@ATP: wide-scan spectra (c); C 1s spectra (d); O 1s spectra (e); Fe 2p spectra (f); S 2p spectra (g) and Si 2p spectra (h).Fig. 3. Changes in the concentration of DTPA-extractable Pb (a) and the concentration of TCLP-leachable Pb (b) during 10 d of incubation; The packing diagram of Pb fractions in sediments after 10 d of incubation (c); Changes in sediment pH (d), Eh (e), and OC (f) content during 10 d of incubation. Different lowercase letters represent significant differences within each treatment using one-way ANOVA (P < 0.05).Fig. 4. Relative abundances of 16S rRNA genes at the phylum (a) and class (b) levels; Hierarchically clustered heat map analysis of community composition at the phylum level in sediment (c); Venn diagram of OTUs (d); and Bray-Curtis distance heatmap between different treatment groups (e).Fig. 5. Changes in sediment urease (a), catalase (b), sucrase (c) after 10 d of incubation and enzyme activities increased or decreased multiples at 10 d (d). Different lowercase letters represent significant differences within each treatment using one-way ANOVA (P < 0.05).Fig. 6. Changes in the concentration of DTPA-extractable Pb (a) and the concentration of TCLP-leachable Pb (b) during 10 d of incubation with lake water and tap water; Changes in the total iron leaching concentration during 10 d of incubation. Different lowercase letters represent significant differences within each treatment using one-way ANOVA (P < 0.05).Fig. 7. Pearson’s correlation coefficients among the DTPA-Pb, TCLP-Pb, fraction of Pb, sediment physicochemical properties, the relative abundance of dominant bacterial communities at the phylum level, and enzyme activities.Fig. 8. The element mapping images (a), EDS spectra (b), XRD spectra (c), and FTIR spectra (d) of S-nZVI@ATP before and after incubation.![]()
Fig. 9. The immobilization mechanisms of Pb contaminated sediments by S-nZVI@ATP.本工作首次研究了S-nZVI@ATP对Pb污染沉积物的固定化作用及其微环境效应：
1、ATP的负载改善了S-nZVI的分散性，丰富了复合材料表面官能团种类。
2、S-nZVI@ATP显著降低了DTPA-Pb和TCLP-Pb，增加了Pb稳定组分的比例（P < 0.05），从而降低了Pb的迁移率。
3、S-nZVI@ATP显著提高了沉积物pH和OC，降低了Eh (P < 0.05)，其中pH的增加和Eh的降低促进了Pb的固定化。
4、ATP、S-nZVI和S-nZVI@ATP的应用均不同程度地影响了沉积物细菌群落的多样性和丰度，变形菌门和厚壁菌门的相对丰度增加，拟杆菌门、酸杆菌门和放线菌门的相对丰度降低。
5、S-nZVI@ATP显著提高了脲酶和过氧化氢酶活性（P < 0.05），且均与DTPA-Pb、TCLP-Pb和Pb的酸溶分数呈极显著负相关（P < 0.01）。
6、通过SEM-EDS、XRD和FTIR对反应后材料进行表征，结果表明S-nZVI@ATP对Pb的固定化主要通过吸附、络合、离子交换、静电吸引、还原和沉淀等作用，固定化产物主要为Pb0、PbS和Pb(OH)2。
Siqi Wen, Weilong Lin, Qi He, Yiqun Xu, Xiaoyu Shi, Jiaming Guo, Yang Gao, Wenjing Xue*, Evaluation of a novel attapulgite loaded sulfidized nanoscale zero-valent iron for immobilization of Pb in sediment: performance, microenvironmental response, and mechanisms, Chemical Engineering Journal, 498 (2024) 155676, https://doi.org./10.1016/j.cej.2024.155676
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