Abstract Adsorption of metal ions at clay surfaces plays a critical role in a variety of geochemical, environmental and engineered processes, and p-DFT calculations with dispersion corrections were employed with aim to comprehensively understand the adsorption of metal ions at hydrated kaolinite surfaces, considering both (00 1 ¯ ) and (001) surfaces and different metal ions (Mn+ = Li+, Na+, K+, Mg2+, Ca2+, Al3+, Fe3+). Ion-specific effects resulting from adsorption also became the focus of this study. For adsorption of alkali ions, inner-sphere complexes dominated for (00 1 ¯ ) surface while owing to hydroxide formation, outer-sphere complexes dominated for (001) surface. Both charge sources and surface structures can significantly alter adsorption structures and their relative stabilities, and surface structures can further perturb ion-specific sequences. Hydroxide formation at (00 1 ¯ ) surface was favored for metal ions (Mn+) of higher oxidation states: Non-existent for M+, geometrically stable but disfavored for M2+ while dominant for M3+. Al3+ adsorption was likely to form AlOH2+, Al(OH)2+ and Al(OH)3 and released more H+ than base cations, which further caused soil acidification. Hydroxide formation affected significantly the extents of ion-specific effects and may further alter their sequences. Results were also helpful to rationalize and guide experimental studies.

中文翻译：

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金属离子在高岭石表面的吸附：离子特异性效应，以及电荷源和氢氧化物形成的影响

摘要 金属离子在粘土表面的吸附在各种地球化学、环境和工程过程中起着至关重要的作用，为了全面了解金属离子在水合高岭石表面的吸附，采用了具有色散校正的 p-DFT 计算。 (00 1 ¯ ) 和 (001) 表面和不同的金属离子（Mn+ = Li+、Na+、K+、Mg2+、Ca2+、Al3+、Fe3+）。吸附产生的离子特异性效应也成为本研究的重点。对于碱离子的吸附，内球配合物主要用于（00 1 ¯ ）表面，而由于氢氧化物的形成，外球配合物主要用于（001）表面。电荷源和表面结构都可以显着改变吸附结构及其相对稳定性，和表面结构可以进一步扰乱离子特异性序列。在 (00 1 ¯ ) 表面形成氢氧化物有利于较高氧化态的金属离子 (Mn+)：对于 M+ 不存在，几何稳定但不利于 M2+ 而对 M3+ 占优势。Al3+吸附很可能形成AlOH2+、Al(OH)2+和Al(OH)3，释放的H+多于碱阳离子，进一步导致土壤酸化。氢氧化物的形成显着影响了离子特异性效应的程度，并可能进一步改变它们的序列。结果也有助于合理化和指导实验研究。Al(OH)2+和Al(OH)3释放的H+多于碱阳离子，进一步导致土壤酸化。氢氧化物的形成显着影响了离子特异性效应的程度，并可能进一步改变它们的序列。结果也有助于合理化和指导实验研究。Al(OH)2+和Al(OH)3释放的H+多于碱阳离子，进一步导致土壤酸化。氢氧化物的形成显着影响了离子特异性效应的程度，并可能进一步改变它们的序列。结果也有助于合理化和指导实验研究。