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Molecular Dynamics Simulations for the Co‐Adsorption of Binary Electrolytes at the Interface of Montmorillonite and Aqueous Solutions
Author(s) -
Yang Sen,
Li Xiong,
Jia Zengqiang,
Li Qinyi,
Yang Gang
Publication year - 2018
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2018.04.0145
Subject(s) - adsorption , electrolyte , ion , chemistry , aqueous solution , montmorillonite , inorganic chemistry , metal ions in aqueous solution , metal , molecular dynamics , chemical physics , computational chemistry , organic chemistry , electrode
Core Ideas Adsorption behaviors for different binary electrolytes at clay surfaces are presented. Major rather than minor adsorption modes are always more affected by co‐ions. Degrees of altering the adsorption numbers and strengths rely strongly on co‐ions. When alone and co‐existent, adsorption modes of metal ions remain consistent. Each binary system has peculiarities during adsorption as discussed in the text. Multiple electrolytes exist in almost all soil systems, and in this work, molecular dynamics was employed to tackle the adsorption of different binary electrolytes (PbCl 2 /CdCl 2 , PbCl 2 /NaCl, PbCl 2 /CsCl and KCl/CsCl) at montmorillonite–water interfaces, providing insights to the mechanisms of co‐adsorption and the impacts of co‐ions. In all cases, the adsorption modes of metal ions are not altered by co‐ions, while co‐ions exhibit the pronounced impacts on the adsorption numbers and strengths, and the main rather than minor adsorption modes are always more affected. In addition to these general principles, each type of binary systems has the peculiarities: Coexistence promotes Pb 2+ adsorption while inhibits Cd 2+ adsorption; Coexistence inhibits Pb 2+ adsorption while promotes Cs + adsorption; Coexistence promotes each other's adsorption of Pb 2+ and Na + ; Coexistence promotes Cs + adsorption while inhibits K + adsorption; All co‐ions improve Pb 2+ stabilities, while coexistence of Pb 2+ reduces Cd 2+ stabilities and improves Cs + and Na + stabilities; Competition for inner‐sphere binding sites is not beneficial for the stabilities of both K + and Cs + . Heavy and radioactive metal ions are a focus of this study and results are also helpful to manage their pollutions.