土壤矿物表面电场对Pb2+吸附的量子调控:极化与极化诱导共价作用
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西南大学资源环境学院,界面过程与土壤健康重庆市重点实验室

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Quantum Regulationof Pb2+ Adsorption by Electric Field at the soil Mineral Surfaces : Polarization and Polarization-induced Covalent Interaction
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Chongqing Key Laboratory of Interface Processes and Soil Health, College of Resources and Environment, Southwest University

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    摘要:

    重金属与矿物颗粒相互作用在重金属钝化/活化过程里扮演着关键角色,但难以定量表征其作用类型和强度。本研究基于轨道杂化理论,定量评估重金属Pb2+在矿物表面的库伦作用、极化作用与极化诱导共价作用及其贡献,阐明了Pb2+在矿物表面吸附的界面调控机制。结果表明,(1)矿物表面电荷数量表现为蒙脱石 > 二氧化硅 > 高岭石 > 赤铁矿,由于比表面积的差异导致表面负电荷密度和电场强度顺序为高岭石 > 二氧化硅 > 蒙脱石 > 赤铁矿;(2)Pb2+的吸附量依赖于矿物表面电荷数量,与电荷数量规律一致,但吸附强度则受表面电场调控;(3)Pb2+在土壤矿物表面的有效电荷系数表现为:高岭石(1.848 ± 0.038) > 蒙脱石(1.782 ± 0.062) > 二氧化硅(1.615 ± 0.029) > 赤铁矿(1.516 ± 0.036),根据有效电荷系数即可评估Pb2+在矿物表面吸附力类型和强度;(4)Pb2+在蒙脱石、高岭石和二氧化硅表面以库仑力吸附为主,占总吸附能的一半以上,在赤铁矿表面则以共价能为主,其贡献达到65%,但依赖于表面电场的极化与极化诱导共价作用对Pb2+吸附有重要调控作用;(5)红外光谱分析表明,随着表面电场增强,含硅矿物表面Si-O键吸收峰蓝移,表明矿物表面O原子与Pb2+间极化诱导共价作用增强。赤铁矿表面强电场增强了-OH基团和H2O分子的极化,Pb2+与OH基团之间产生了共价相互作用,从而使Fe-O-Fe键随pH升高而增强。本研究证明土壤矿物表面吸附Pb2+存在极化与极化诱导共价作用,并定量评估了其贡献。Pb2+有效电荷系数随表面电场强度增强而增大,矿物表面与Pb2+间极化与极化诱导共价作用随pH升高而增强,表明极化与极化诱导共价作用对Pb2+-矿物表面相互作用的重要影响。此研究为进一步通过对作用力的调节,定向调控土壤重金属的钝化/活化奠定理论基础。

    Abstract:

    【Objective】The interactions between heavy metals and mineral particles play a key role in the passivation/activation of heavy metals, significantly impacting on soil health, food safety and ecological stability. However, quantitatively characterizing the type and intensity of these interactions remains challenging. 【Method】Based on orbital hybridization theory, this study quantitatively evaluated the polarization, polarization-induced covalent interactions and Coulomb interactions of the heavy metal Pb2+ on mineral surfaces.【Result】The results show that: (1) The surface charge number follows the order: montmorillonite > silica > kaolinite > hematite. However, the order of surface negative charge density and electric field strength is kaolinite > silica > montmorillonite > hematite, due to differences in specific surface area. (2) The adsorption capacity of Pb2+ depends on the surface charge number, consistent with its trend, while the adsorption strength is governed by the surface electric field (3) Effective charge coefficients of Pb2+ on soil mineral surfaces, quantified using orbital hybridization theory, averaged as following: kaolinite (1.848 ± 0.038) > montmorillonite (1.782 ± 0.062) > silica (1.615 ± 0.029) > hematite (1.516 ± 0.036), demonstrating a positive correlation with surface electric field intensity. (4) The adsorption of Pb2+ on the surfaces of montmorillonite, kaolinite, and silica is primarily driven by Coulombic forces, which account for more than half of the total adsorption energy. In contrast, adsorption on the surface of hematite is mainly governed by covalent interactions, contributing approximately 65%. Additionally, polarization effects dependent on the surface electric field and polarization-induced covalent interactions play a crucial regulatory role in the adsorption of Pb2+. (5) Infrared spectroscopy analysis revealed that the absorption peak of the Si-O bond on the surface of silicon-containing minerals shifts to higher frequencies (blue shifts) as the surface electric field increases. This shift indicates an enhanced polarization-induced covalent interaction between O atoms and Pb2+ on the mineral surfaces. The strong electric field on the surface of hematite enhances the polarization of the -OH group and H2O molecules, leading to the formation of covalent interactions between Pb2+ and -OH groups. Consequently, the Fe-O-Fe bonds are strengthened as the pH increases. 【Conclusion】This study demonstrated that the adsorption of Pb2+ on the surface of soil minerals has polarization and polarization-induced covalent effects, and quantitatively evaluated its contribution. The effective charge coefficient of Pb2+ increases with the increase of surface electric field strength, and the polarization and polarization-induced covalent interaction between mineral surface and Pb2+ increase with the increase of pH, indicating that polarization and polarization-induced covalent interaction have an important influence on the interaction between Pb2+ and mineral surface. This research establishes a theoretical foundation for the directional regulation of heavy metal passivation/activation in soils through modulation of interfacial forces.

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曲佳雯,唐雨婷,席淑宁,刘新敏.土壤矿物表面电场对Pb2+吸附的量子调控:极化与极化诱导共价作用[J].土壤学报,,[待发表]
QU Jiawen, TANG YUting, XI Shuning, LIU Xinmin. Quantum Regulationof Pb2+ Adsorption by Electric Field at the soil Mineral Surfaces : Polarization and Polarization-induced Covalent Interaction[J]. Acta Pedologica Sinica,,[In Press]

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  • 收稿日期:2025-09-09
  • 最后修改日期:2026-03-10
  • 录用日期:2026-04-27
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