Effects of Different Anions on Negatively Charged Colloidal Aggregation of Montmorillonite
Author(s): FU Qiang, GUO Xia, TIAN Rui, LI Hang, School of Resources and Environment, Southwest University, Chongqing Key Laboratory of Soil Multi-Scale Interfacial Process
Pages: 28-34
Year: 2016 Issue: 4
Journal: Journal of Southwest Agricultural University
Keyword: light scattering; anion; aggregation; Hofmeister effects;
Abstract: Hofmeister effects,or specific ion effects,are prevalent in the solid/liquid interface reaction.Various kinds of anions and cations are present in the soil solution,and because the soil carries a net negative charge,the effects of anions are believed to be so weak that they can be neglected.In the present study,the effects of the interfacial reactions of three mono-valent anions（H2PO4-,Cl- and NO3-）on the aggregation of montmorillonite particles were studied,based on the dynamic light scatting technique.The main results of this study were as follows.The montmorillonite aggregation rate in the three anions systems differed significantly.The CCC values obtained for H2PO4-,Cl- and NO3- were 79.29,13.91,and 17.07mmol/L,respectively.The activation energies reflecting specific ion effects in natural soil aggregation process ranked as H2PO4->NO3->Cl-,indicating that the anion-specific effects can significantly affect negatively charged colloidal aggregates.The above-mentioned differences can be interpreted by the polarization effects of the three anions resulting from their extranuclear cloud structure.
Pages: 28-34
Year: 2016 Issue: 4
Journal: Journal of Southwest Agricultural University
Keyword: light scattering; anion; aggregation; Hofmeister effects;
Abstract: Hofmeister effects,or specific ion effects,are prevalent in the solid/liquid interface reaction.Various kinds of anions and cations are present in the soil solution,and because the soil carries a net negative charge,the effects of anions are believed to be so weak that they can be neglected.In the present study,the effects of the interfacial reactions of three mono-valent anions（H2PO4-,Cl- and NO3-）on the aggregation of montmorillonite particles were studied,based on the dynamic light scatting technique.The main results of this study were as follows.The montmorillonite aggregation rate in the three anions systems differed significantly.The CCC values obtained for H2PO4-,Cl- and NO3- were 79.29,13.91,and 17.07mmol/L,respectively.The activation energies reflecting specific ion effects in natural soil aggregation process ranked as H2PO4->NO3->Cl-,indicating that the anion-specific effects can significantly affect negatively charged colloidal aggregates.The above-mentioned differences can be interpreted by the polarization effects of the three anions resulting from their extranuclear cloud structure.
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