不同电解质体系中土壤胶体凝聚动力学的动态光散射研究-朱华玲

[Article]www.whxb.pku.edu.cn物理化学学报(WuliHuaxueXuebao)ActaPhys.-Chim.Sin.,2009,25(6)：1225-1231JuneReceived:December8,2008;Revised:March12,2009;PublishedonWeb:April16,2009.*Correspondingauthor.Email:hli22002@yahoo.com.cn;Tel:+8623-68250674.国家自然科学基金(40371061)和重庆市教委科学技术研究项目(KJ050205)资助鬁EditorialofficeofActaPhysico-ChimicaSinica不同电解质体系中土壤胶体凝聚动力学的动态光散射研究朱华玲李兵熊海灵李航*贾明云(西南大学资源环境学院,重庆400716)摘要：利用动态光散射技术研究在不同浓度的KNO3和Mg(NO3)2中土壤胶体颗粒的凝聚过程动力学.通过分析凝聚过程中光强和有效粒径随时间的变化得到:(1)根据凝聚过程中光强的稳定与否,可以判断土壤胶体凝聚过程中碰撞的发生是由布朗运动支配还是由重力作用支配;(2)在不同的电解质体系下土壤胶体凝聚表现为快速凝聚特征或不同的慢速凝聚特征,并且在慢速凝聚中存在一个对重力敏感的电解质浓度;(3)两种电解质作用下的土壤胶体凝聚特征相似,但对Mg(NO3)2体系浓度变化的敏感性远远大于KNO3体系.此外,通过分析凝聚平均速率随电解质浓度的变化,找到慢速凝聚与快速凝聚的电解质浓度转折点,即临界絮凝浓度(CFC),提供了一个实验测定CFC的可能方法.关键词：动态光散射;土壤胶体;快速凝聚;慢速凝聚;动力学中图分类号：O648DynamicLightScatteringStudyontheAggregationKineticsofSoilColloidalParticlesinDifferentElectrolyteSystemsZHUHua-LingLIBingXIONGHai-LingLIHang*JIAMing-Yun(CollegeofResourceandEnvironment,SouthwestUniversity,Chongqing400716,P.R.China)Abstract：SoilcolloidalaggregationkineticswasstudiedatdifferentconcentrationsofKNO3andMg(NO3)2bydynamiclightscattering.Byanalyzingthechangeinlightintensityandeffectivediameterofaggregateswithtime,weconcludethat:(1)ThestabilityofthelightintensityinanaggregationprocessisabasisforjudgingifthecollisionisdominatedeitherbyBrownforceorgravity;(2)Withdifferentelectrolytesystems,soilcolloidalaggregationexhibitsafastdiffusion-limitedclusteraggregation(DLCA)characterorvariousslowreactionlimitedclusteraggregation(RLCA)charactersandagravitysensingelectrolyteconcentrationexistsinRLCA;(3)TheaggregationcharactersinducedbytwoelectrolytesareessentiallysimilarbuttheaggregatingprocessismoresensitivetotheMg(NO3)2electrolyteconcentrationchangethantoKNO3.Byanalyzingthechangeofaverageaggregationvelocitywithelectrolyteconcentration,theturningpointwhereelectrolyteconcentrationchangesfromslowtofastaggregationisdesignatedasthecriticalflocculationconcentration(CFC).AnewmethodformeasuringtheCFCexperimentallyisthusprovided.KeyWords：Dynamicligh