蒙脱石纳米颗粒聚集中的离子特异性效应  

Specific Ion Effect of Aggregating Montmorillonite Nanoparticles

作　　者：刘汉燚 刘新敏[1] 田锐[1] 李航[1] 李睿[1] LIU Hanyi;LIU Xinmin;TIAN Rui LI;Hang LI Rui(Chongqing Key Laboratory of Soil Multi-scale Interfacial Process, College of Resources and Environment, Southwest University, Chongqing 400715, China)

机构地区：[1]土壤多尺度界面过程与调控重庆市重点实验室西南大学资源环境学院,重庆400715

出　　处：《土壤学报》2018年第3期673-682,共10页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(41530855;41501240;41501241)资助~~

摘　　要：原子力显微镜(AFM)是一种研究颗粒聚集与黏附力比较直观的显微工具。运用原子力显微镜观察测定了几种碱金属氯化盐溶液处理的蒙脱石颗粒在风干条件下的形貌图和黏附力。结果发现,蒙脱石颗粒聚集存在明显的离子特异性效应。在50 mmol L^(-1)的高浓度条件下,CsCl体系中蒙脱石颗粒聚集的高度、直径以及针尖与颗粒的黏附力均存在离子特异性效应,其序列满足LiCl<NaCl<KCl<RbCl<CsCl。在10 mmol L^(-1)的低浓度条件下,除Cs^+处理蒙脱石高度为2~10 nm,其余高度均为1~2 nm的单粒,离子特异性效应不明显。影响颗粒聚集中的离子特异性效应的主要因素为离子体积和量子涨落效应,在低浓度下量子涨落和体积效应作用弱,因此聚集行为差异不明显;在高浓度下离子体积和量子涨落贡献大,导致了不同离子体系下颗粒聚集体以及与针尖的黏附力差异增大。【Objective】The phenomenon of aggregation of colloid particles varying from ion to ion the same in valence in solutions the same in electrolyte concentration is referred to as specific ion effect or Hofmeister effect. In this study, aggregation of montmorillonite colloid particles were observed under an atomic force microscope（AFM） and their adhesion force measured, in an attempt to analyze specific ion effect of the particles in aggregation and hence to provide experimental support to theoretical studies on interactions between ions and particles, and references for further studies on specific ion effects of aggregating particles in strong electric fields.【Method】The montmorillonite particles that had gone through a 200 mesh sieve were added into LiCl, KCl, NaCl, RbCl and CsCl solutions 10, 30 and 50 mmol L-1 in concentration, separately, and prepared into montmorillonite suspensions, which were then dripped onto mica sheets, separately, air dried, and scanned with AFM. 【Result】（1） With rising concentration of electrolyte in the system, aggregation of montmorillonite particles occurred horizontally first and then vertically.（2）In solutions varying in electrolyte, but the same in concentration, the montmorillonite particles aggregation degree exhibited obvious specific ion effects. The montmorillonite particles in all the electrolyte solutions 10 mmol L-1 in concentration were all around 1 nm in height; in the Cs＋ system, montmorillonite particles were about 300 nm in diameter, and aggregated horizontally, while those in the other ionic systems were merely 100 nm, and did not aggregate horizontally. In the electrolyte solutions 30 mmol L-1 in concentration, Montmorillonite particles in the Rb～＋ system reached 400 nm in diameter and about 4 nm in maximum height, which indicates that the particles aggregated horizontally, and vertically, too, though not much, and in the Cs＋ system, Montmorillonite particles did aggregate horizontally and vertically. And in the solutions 50 mmol L-1 in

关 键 词：原子力显微镜(AFM) 蒙脱石 聚集 离子特异性效应 黏附力 

分 类 号：S153.3[农业科学—土壤学]