| 摘要: |
| 我国目前土壤重金属污染形势严峻，土壤污染防治工作进入战略性阶段。铁锰氧化物在土壤中广泛赋存，对环境中重金属具有显著的吸附络合作用，含氧阴离子的存在极大地影响重金属在土壤环境中的迁移转化，因此深入探究重金属和含氧阴离子在铁锰氧化物表面的吸附络合及其相互作用机制，对阐明重金属在土壤环境中的迁移转化过程具有重要意义。通过介绍土壤中常见的铁锰氧化物，总结铁锰氧化物对重金属离子、含氧阴离子的吸附络合、相互作用机制及其影响因素，对近年来的相关模型和常用检测技术方法进行综述，最后针对土壤铁锰氧化物和重金属界面交互过程研究领域存在的局限，提出未来潜在研究方向，对土壤系统和污染修复研究具有重要指导意义。 |
| 关键词: 铁锰氧化物 重金属 含氧阴离子 吸附络合 |
| DOI：10.7515/JEE221031 |
| CSTR：32259.14.JEE221031 |
| 分类号: |
| 基金项目:国家重点研发计划（2020YFC1807600）；国家自然科学基金项目（42207005） |
| 英文基金项目:National Key Research and Development Program of China (2020YFC1807600); National Natural Science Foundation of China (42207005) |
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| Research progress on the mechanism for the adsorption and complexation of heavy metals onto iron and manganese oxides and its inf luencing factors in soil environment |
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HUANG Wenyan1, YANG Wenjun1*, TANG Yetao1, QIU Rongliang1, 2, 3
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1. School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory for Environmental Pollution Control and Remediation Technology, Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, Sun Yat-sen University, Guangzhou 510006, China
2. College of Natural Resources and Environment, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, South China Agricultural University, Guangzhou 510642, China
3. Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
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| Abstract: |
| Background, aim, and scope Currently, our country’s soil heavy metal (HM) pollution situation is severe, and the task for soil prevention and pollution control has entered a strategic stage. Iron and manganese oxides are widespread in soil. HMs are readily adsorbed by iron and manganese oxides due to their high surface activity and large specific surface area. Meanwhile, the existence of oxyanions also has a great effect on the adsorption and complexion of HMs. It is therefore important to investigate the molecular mechanism of the adsorption, complexation and the interaction with HMs and oxyanions on iron and manganese oxides. And it is also of great significance for us to elucidate the migration and transformation processes of HMs in the soil. Materials and methods This review introduces the common iron and manganese oxides in soil, summarizes the mechanism and influencing factors of HMs and oxyanions adsorbed on iron and manganese oxides, and reviews the related models and common detection techniques in recent years. Results The ions are adsorbed on the surface of iron and manganese oxides through specific and non-specific adsorption. Electrostatic interaction, the formation of ternary complexes and surface precipitation promote the adsorption of oxyanions and HMs onto iron and manganese oxides. Various environmental factors such as pH, Eh, ionic strength, organic matter, the properties of oxyanions and oxides will affect the adsorption and interaction of ions on iron and manganese oxides. In addition to the classical adsorption isotherms Langmuir and Freundlich, the surface complexation models such as charge distribution-multisite complexation models (CD-MUSIC) are commonly used to describe the adsorption process. The Fourier transform infrared spectroscopy (FTIR), X-ray absorption fine structure (XAFS), mathematical analysis and quantum chemical calculations are often conducted to interpret the surface complexation products, and to represent the mechanisms at the molecular level. Discussion Compared to iron oxides, few studies have been performed regarding the adsorption mechanism of the ion adsorbed on manganese oxides in soil environments, especially under the coexistence of heavy metal ions and oxyanions conditions. There is still a lack of systematic comparison and exploration of the changes in adsorption characteristics caused by the properties of oxyanions. Moreover, there are relatively few reports about the adsorption mechanism of crystal planes and adsorption sites. Meanwhile, the previous studies of the molecular scale focus on laboratory experiments which mainly used single mineral as experimental material, it is supposed that these conclusions are not applicable in the nature environment. At this stage, the study of single-factor effects on the dynamic process of the adsorption and complexation of heavy metals is relatively extensive. The further study of coupled reaction kinetic models should be paid more attention, which could help us resolve the multivariable coupling process of the adsorption and complexation. Conclusions At present, there have been systematic studies on the adsorption and complexation, influencing factors and interactions of HMs and oxyanions on iron and manganese oxides. The combined application of several models and test techniques makes the interpretation of the adsorption process and the structure of complexes clearer. Recommendations and perspectives Therefore, future research could focus on the properties of manganese oxides and oxyanions, as well as the effect of oxide crystal planes on the adsorption and complexation processes. These applicability of laboratory studies are meaningful for complex natural soil system and contaminated soil remediation research. More attention should be paid to the application of laboratory experimental mechanisms in more complicated natural environments. |
| Key words: iron and manganese oxide heavy metal oxyanion adsorption complex |
