State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China.
State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
J Hazard Mater. 2023 Feb 5;443(Pt B):130259. doi: 10.1016/j.jhazmat.2022.130259. Epub 2022 Oct 26.
Sulfidation effectively improves the electron transfer efficiency of nanoscale zero-valent iron (nZVI), but decreases the specific surface area of nZVI. In this study, sulfidated nZVI (S-nZVI) coated with rhamnolipid (RL-S-nZVI) was synthesized and used to stabilize Pb, Cd, and As in combined polluted soil. The stabilization efficiency of 0.3% (wt) RL-S-nZVI to water soluble Pb, Cd, and As in soil reached 88.76%, 72%, and 63%, respectively. Rhamnolipid coating inhibited the reduction of specific surface area and successfully encapsulated nZVI, thus reducing the oxidation of Fe. The types of iron oxides in RL-S-nZVI were reduced compared to S-nZVI, but the content and strength of Fe iron were obviously enhanced. Furthermore, rhamnolipid functional groups (-COOH and -COO) were also involved in the stabilization process. In addition, the stabilization efficiency of RL-S-nZVI to the bioavailable Pb, Cd, and As in soil increased by 41%, 41%, and 50%, respectively, compared with nZVI. The presence of organic acids, especially citric acid, improved the stabilization efficiency of RL-S-nZVI to the three metals. The result of BCR sequential extraction indicated that RL-S-nZVI increased the residual state of Pb, Cd, and As and reduced the acid-soluble and reducible state after 28 days of soil incubation. XRD and XPS analyses showed that the stabilization mechanisms of RL-S-nZVI on heavy metals involved in ion exchange, surface complexation, adsorption, co-precipitation, chemisorption, and redox.
硫化作用能有效提高纳米零价铁（nZVI）的电子传递效率，但会降低 nZVI 的比表面积。本研究合成了油酰胺基琥珀酸单酯磺酸钠（RL-S-nZVI）包覆的硫化纳米零价铁（S-nZVI），并将其用于稳定复合污染土壤中的 Pb、Cd 和 As。0.3%（wt）RL-S-nZVI 对土壤中水溶性 Pb、Cd 和 As 的稳定效率分别达到 88.76%、72%和 63%。油酰胺基琥珀酸单酯磺酸钠的包覆抑制了比表面积的降低，并成功包裹了 nZVI，从而减少了 Fe 的氧化。与 S-nZVI 相比，RL-S-nZVI 中氧化铁的类型减少，但 Fe 的含量和强度明显增强。此外，油酰胺基琥珀酸单酯磺酸钠的功能基团（-COOH 和 -COO）也参与了稳定过程。此外，与 nZVI 相比，RL-S-nZVI 对土壤中生物有效态 Pb、Cd 和 As 的稳定效率分别提高了 41%、41%和 50%。有机酸的存在，特别是柠檬酸，提高了 RL-S-nZVI 对三种金属的稳定效率。BCR 连续提取结果表明，RL-S-nZVI 增加了 Pb、Cd 和 As 的残渣态含量，降低了土壤培养 28 天后酸可提取态和可还原态含量。XRD 和 XPS 分析表明，RL-S-nZVI 对重金属的稳定机制涉及离子交换、表面络合、吸附、共沉淀、化学吸附和氧化还原。
