ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2024
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IF 10.8
Wanli Lian,Guanghui Yu,Jie Ma,Juan Xiong,Cuiyun Niu,Ran Zhang,Haijiao Xie,Liping Weng
Despite extensive study, geochemical modeling often fails to accurately predict lead (Pb) immobilization in environmental samples. This study employs the Charge Distribution MUlti-SIte Complexation (CD-MUSIC) model, X-ray absorption fine structure (XAFS), and density functional theory (DFT) to investigate mechanisms of phosphate (PO4) induced Pb immobilization on metal (hydr)oxides. The results reveal that PO4 mainly enhances bidentate-adsorbed Pb on goethite via electrostatic synergy at low PO4 concentrations. At relatively low pH (below 5.5) and elevated PO4 concentrations, the formation of the monodentate-O-sharing Pb-PO4 ternary structure on goethite becomes important. Precipitation of hydropyromorphite (Pb5(PO4)3OH) occurs at high pH and high concentrations of Pb and PO4, with an optimized log Ksp value of −82.02. The adjustment of log Ksp compared to that in the bulk solution allows for quantification of the overall Pb-PO4 precipitation enhanced by goethite. The CD-MUSIC model parameters for both the bidentate Pb complex and the monodentate-O-sharing Pb-PO4 ternary complex were optimized. The modeling results and parameters are further validated and specified with XAFS analysis and DFT calculations. This study provides quantitative molecular-level insights into the contributions of electrostatic enhancement, ternary complexation, and precipitation to phosphate-induced Pb immobilization on oxides, which will be helpful in resolving controversies regarding Pb distribution in environmental samples.
研究领域:
环境科学
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地球化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF SOILS AND SEDIMENTS
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2021
·Vol. 21
·期 7
·2540-2550
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IF 3.308
Yang Han,Ye Zhi,Feng Fang,Xu Nan,Yang Jing,Yao Zihan,Li Zuling,Chen Jianping
Purpose Lead (Pb(II)) can be accumulated in soil and transferred to humans via the food chain. Therefore, it is essential to improve Pb(II) immobilization during soil remediation. Materials and methods Nanosized zero-valent iron (nZVI) from green tea extract (tea polyphenols, TPs) was successfully synthesized as an additive reductant. Further, the nZVI was supported on montmorillonite (Mont), resulting in a GT-nZVI@Mont composite characterized by multiple techniques, including Zeta potential, SEM, TEM, XRD, and XPS. Moreover, the transport experiments and the toxicity characteristic leaching procedure (TCLP) were conducted to identify the optimum conditions (i.e., GT-nZVI@Mont dosage, Pb(II) concentration, and pH) for the remediation. Results and discussion The experimental results showed that the enhanced transportability of GT-nZVI@Mont was about 40% more than that of GT-nZVI. Meanwhile, Pb(II) immobilization was increased at various pH values (especially under anoxic conditions). The Pb(II) immobilization capacity of GT-nZVI@Mont was 900.8 mg∙g -1 (per unit of Fe content), which was significantly higher than 530.1 mg∙g -1 per unit of Fe content in GT-nZVI. Such enhancement could be ascribed to the synergistic effects of the wrapped TP around the Fe 0 core and the Mont interlayer support, capable of protecting the Fe 0 surface from further oxidation. When GT-nZVI@Mont reacted with the Pb(II) in soil, TPs’ unwrapped coverage increased the reaction sites of Fe 0 cores for Pb(II) reduction and adsorption. Conclusions GT-nZVI@Mont with sufficient transportability provided efficient in situ remediation of Pb(II) in contaminated soil at a wide pH range.
研究领域:
环境科学
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纳米材料
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土壤学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2023
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IF 13.6
Junpeng Li,Rui Bai,Wei Chen,Chongyuan Ren,Fan Yang,Xiaochun Tian,Xiaofeng Xiao,Feng Zhao
Mineralization of lead ions (Pb 2+ ) to pyromorphite using phosphorus-containing materials is an effective way to remediate lead (Pb) contamination. Bone char is rich in phosphorus, but its immobilization of Pb 2+ is limited by poor phosphate release. To utilize the phosphorus in bone char and provide a suitable growth environment for phosphate-solubilizing bacteria, bone char and Pseudomonas rhodesiae HP-7 were encapsulated into bio-beads, and the immobilization performance and mechanism of Pb in solution and soil by bio-beads were investigated. The results showed that 137 mg/g of phosphorus was released from bone char in the presence of the HP-7 strain. Pb 2+ removal efficiency reached 100 % with an initial Pb 2+ concentration of 1 mM, bone char content of 6 g/L, and bio-bead dosage of 1 %. Most Pb 2+ was immobilized on the surface of the bio-beads as Pb 5 (PO 4 ) 3 Cl. The soil remediation experiments showed a 34 % reduction in the acid-soluble fraction of Pb. The bio-beads showed good stability in long-term (30 d) soil remediation. The present study shows that bone char can be turned into an efficient Pb immobilization material in the presence of phosphate-solubilizing bacteria. Thus, bio-beads are expected to be used in the remediation of Pb-contaminated environments.
研究领域:
环境科学
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微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2023
·
IF 9.8
Qihui Yu,Hao Liu,Guocheng Lv,Xin Liu,Lijuan Wang,Libing Liao
The contamination of heavy metal lead has a serious impact on the natural environment and organisms. Among various materials for lead removal, animal bone derived hydroxyapatite has received extensive attention. However, there are different opinions among researchers regarding the mechanism of lead removal by hydroxyapatite , possibly due to varying initial lead concentrations used in different studies and lack of accuracy in the study of lead removal mechanisms. In present work, we synthesized a carbon-containing hydroxyapatite (CHAP) through pyrolysis of bovine bone with excellent lead removal efficiency, and further investigated the lead removal mechanism of CHAP under high and low initial lead concentrations by combining XRD Rietveld refinement, FTIR, XPS, HRTEM etc. methods. The results showed that under low initial Pb 2+ concentration condition, the main mechanism of lead removal by CHAP was chemical precipitation (94.1 %), with small contributions of lead complexation with carbon functional groups and cation-π interactions on the amorphous carbon in CHAP, and surface adsorption on the precipitates. Under high initial Pb 2+ concentration condition, chemical precipitation remained the main mechanism (74.68 %), but the contributions of the other three mechanisms increased, and ion exchange appeared in the later stage of the removal process. This study provides new insights on the lead immobilization mechanism by CHAP at different initial Pb 2+ concentrations in water.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）