蒙脱石表面碱金属离子的亚稳平衡吸附及其特异性效应
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1.西北农林科技大学资源环境学院/农业农村部西北植物营养与农业环境重点实验室;2.中国科学院水利部水土保持研究所/西北农林科技大学黄土高原土壤侵蚀与旱地农业国家重点实验室

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S153.3

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国家自然科学基金项目(42107332,42077135)、陕西省自然科学基础研究计划(2021JQ-170)和西北农林科技大学博士科研启动项目(2452018041)资助


Metastable Equilibrium Adsorption of Alkali Metal Ions on the Surface of Montmorillonite and Its Specific Effects
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Affiliation:

1.College of Natural Resources and Environment,Northwest A F University/Key Laboratory of Plant Nutrition and the Agri-Environment in Northwest China,Ministry of Agriculture and rural areas,Yangling;2.Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources/State Key Laboratory of Soil Erosion and Dryland Agriculture on the Loess Plateau,Northwest A F University;3.China

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Supported by the National Natural Science Foundation of China (Nos. 42107332, 42077135), Natural Science Basic Research Program of Shaanxi Province (No. 2021JQ-170) and Doctoral Research Startup Project of Northwest A&F University, China (No. 2452018041).

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    摘要:

    离子吸附的亚稳平衡是描述离子交换吸附中实际反应平衡特征及限度的重要理论范式。本研究旨在从理论上推导离子吸附的亚稳态平衡模型,建立离子平衡吸附量与活化能之间的数学关系,探讨碱金属离子亚稳平衡吸附的特异性效应。结合恒流混合置换技术及基于表面静电场理论的离子吸附动力学模型,探究了钾离子(K+)、钠离子(Na+)、锂离子(Li+)三种碱金属离子在铯离子(Cs+)-蒙脱石饱和样表面可能存在的亚稳平衡吸附作用。通过开展K+、Na+和Li+在Cs+-蒙脱石表面的吸附动力学实验,对理论模型进行验证。研究结果表明:(1)K+、Na+、Li+在Cs+-蒙脱石饱和样表面表现出显著的亚稳平衡吸附特征,交换离子的吸附活化能(能量势垒)来源于吸附态Cs+的解吸过程;(2)相同离子浓度条件下,表面静电场引起的离子强极化作用导致各离子的亚稳平衡吸附呈现出特异性效应;(3)离子吸附的亚稳平衡受到离子浓度和离子特异性效应的共同影响,离子平衡吸附量与离子吸附速率呈正比例关系。碱金属离子在蒙脱石表面的吸附平衡是亚稳平衡而不是真正的平衡,离子亚稳平衡吸附的存在应归因于活化能对离子吸附动力学的限制。碱金属离子不同的极化效应导致各体系的活化能不同,进一步触发了离子亚稳态平衡吸附的特异性效应。

    Abstract:

    【Objective】Metastable equilibrium is an important theoretical paradigm to describe the characteristics and extent of the actual reaction equilibrium in ion-exchange adsorption. This study aimed to theoretically derive the metastable equilibrium model of ion adsorption, establish the mathematical relationship between ion equilibrium adsorption amount and activation energy, and discuss the specific effect of alkali metal ion metastable equilibrium adsorption. 【Method】Using miscible displacement technology combined with the ion adsorption kinetic model and based on surface electrostatic field theory, the metastable equilibrium adsorption of K+, Na+, and Li+ on the surface of saturated Cs+-montmorillonite was investigated. The theoretical model was verified by carrying out adsorption kinetics experiments of K+, Na+, and Li+ on the Cs+-montmorillonite surface. 【Result】(1) Significant metastable equilibrium characteristics were observed during K+, Na+, and Li+ adsorption onto the surface of Cs+-montmorillonite saturated samples, and the adsorption activation energy (energy barrier) of exchange ions came from the desorption process of adsorbed Cs+; (2) Strong ion polarization caused by the surface electrostatic field resulted in specific effect of metastable equilibrium adsorption of each ion under the same ion concentration condition; (3) The metastable equilibrium of ion adsorption was affected by both ion concentration and specific ion effects, and the ion equilibrium adsorption capacity was proportional to the ion adsorption rate. 【Conclusion】The adsorption equilibrium of alkali metal ion at the montmorillonite surface is a metastable equilibrium rather than a real equilibrium. The presence of ionic metastable adsorption equilibrium should be attributed to the restraint of activation energies to ion adsorption kinetics. Also, the different polarization effects of alkali metal ions lead to different activation energies of each system, which further triggers the specific effect of ion metastable equilibrium adsorption.

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杜伟,胡斐南,许晨阳,李雄,吕家珑.蒙脱石表面碱金属离子的亚稳平衡吸附及其特异性效应[J].土壤学报,,[待发表]
DU Wei, HU Feinan, XU Chenyang, LI Xiong, LV Jialong. Metastable Equilibrium Adsorption of Alkali Metal Ions on the Surface of Montmorillonite and Its Specific Effects[J]. Acta Pedologica Sinica,,[In Press]

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