摘要
为探究HPO4^2–和H2PO4^–界面行为对土壤胶体凝聚的影响,以蒙脱石和胡敏酸胶体为研究对象,采用动态光散射技术比较研究HPO4^2–和H2PO4^–引发胶体颗粒凝聚过程的差异.结果表明,随着电解质离子强度的升高,HPO4^2–和H2PO4^–体系蒙脱石-胡敏酸混合悬液从慢速凝聚(线性增长)转化为快速凝聚(幂函数增长),但胶体凝聚过程对H2PO4^–体系离子强度的变化更敏感.HPO4^2–和H2PO4^–作用下凝聚体有效粒径增长、总体平均凝聚速率(TAA)、临界聚沉离子强度(CCIS)和活化能均存在明显差异;其中,与HPO4^2–相比,H2PO4^–体系中拥有更高的TAA、更低的CCIS和活化能,说明H2PO4–离子引发蒙脱石-胡敏酸混合胶体凝聚的作用更强,HPO4^2–体系中CCIS是H2PO4–中的2.43倍.HPO42–和H2PO4–体系中离子特异性效应的差异(活化能差值)随离子强度的降低而增大,主要由强电场中离子非经典极化作用引发.胡敏酸的添加明显增加了HPO42–体系中胶体的CCIS和活化能,而对H2PO4–体系未产生明显影响;HPO42–和H2PO4–离子特异性效应的强弱在不同比例蒙脱石/胡敏酸体系中表现为96%蒙脱石+4%胡敏酸>>99%蒙脱石+1%胡敏酸>100%蒙脱石.以上结果表明HPO4^2–和H2PO4^–对蒙脱石-胡敏酸混合胶体的凝聚存在强烈的离子特异性效应,胶体表面附近电场强度直接影响该效应的强弱.
In order to investigate the effect of interfacial behaviors of HPO4^2– and H2PO4^– on soil colloids aggregation,the aggregation kinetics of montmorillonite and humic colloids were monitored using a dynamic light scattering instrument.Results showed that the colloids aggregation in the HPO4^2– and H2PO4^– systems transformed from slow aggregation(linear growth)to fast aggregation(power function growth)with increasing ionic strength of the electrolytes.In addition,the aggregation was more sensitive to the changes in ionic strength in H2PO4^– system.Significant differences of the growth of effective particle size,total average aggregation(TAA)rate,critical coagulation ionic strength(CCIS),and activation energy were observed in colloids aggregation in the HPO4^2– and H2PO4^– systems.Compared with aggregation in HPO4^2– system,aggregation in H2PO4^– system has a higher TAA rate,lower CCIS and lower activation energy,indicating that H2PO4^– has a stronger effect on initiating colloid aggregation.Besides,the CCIS of HPO4^2– was 2.43 times as that of H2PO4^–.The difference of activation energies between the two systems increased with decreasing ionic strength,which might be caused by the ionic non-classical polarization in the strong external electric field.The addition of humic colloids significantly increased the CCIS and activation energy in HPO4^2– system,but not in H2PO4^– system.The Hofmeister effects of HPO4^2– and H2PO4^– on colloids aggregation followed the order of 96%montmorillonite+4%humic colloid>>99%montmorillonite+1%humic colloid>100%montmorillonite.These results indicated that there are strong Hofmeister effects of HPO4^2– and H2PO4^– on the aggregation of montmorillonite-humic colloids,and the Hofmeister effects were directly dependent on the electric field strength near the surface of the colloids.
作者
徐英德
汪景宽
李双异
高晓丹
XU Ying-de;WANG Jing-kuan;LI Shuang-yi;GAO Xiao-dan(College of Land and Environment,Shenyang Agricultural University,Shenyang 110866,China;College of Resources and Environment,Southwest University,Chongqing 400715,China)
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2019年第9期3914-3924,共11页
China Environmental Science
基金
国家自然科学基金资助项目(41601230)
中国博士后科学基金资助项目(2017M611265)
国家重点研发计划项目(2016YFD0200304)
