单一电解质体系下恒电荷土壤胶体扩散双电层中滑动层厚度的计算  

CALCULATION OF THICKNESS OF SHEAR PLANE IN DIFFUSE DOUBLE LAYER OF CONSTANT CHARGE SOIL COLLOID IN SINGLE ELECTROLYTE SYSTEM

作　　者：丁武泉[1,2] 朱启红[1] 王磊[1] 罗雅雪 李强[1] 朱华玲[2] 胡斐南[2] 朱龙辉[2] 李航[2] 

机构地区：[1]环境材料与修复技术重庆市重点实验室,重庆文理学院水环境修复重点实验室,重庆文理学院材料与化工学院,重庆402160 [2]土壤多尺度界面与过程调控重庆市重点实验室,西南大学资源环境学院,重庆400716

出　　处：《土壤学报》2015年第4期859-868,共10页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(41101223);重庆市自然科学基金项目(cstc2014jcyj A80031,CSTC2013jcyj A20024);中央高校基本业务费专项资金项目(XDJK2014D049);重庆市大学生创新创业训练计划项目(201410642005)资助

摘　　要：土壤胶体颗粒表面滑动层厚度是一个重要的物理参数。利用Gouy-Chapman理论推导得到单一电解质体系中滑动层厚度计算公式,测得三种紫色土胶体颗粒表面电位值和ζ电位值,通过计算得到滑动层厚度值。结果表明:(1)在2∶1型电解质体系中三种紫色土胶体表面电位和zeta电位绝对值均远低于1∶1型电解质体系,两种单一电解质体系下三种紫色土表面电位值随电解质浓度变化差异要远大于zeta电位值;(2)两种单一电解质体系下三种紫色土胶体滑动层均离双电层中Stern层较远,而与Gouy层靠近,并且在2∶1电解质体系中的滑动层厚度要远低于1∶1电解质体系;(3)三种紫色土胶体颗粒随着电解质浓度升高,其滑动厚度均变薄。不同表面电位土壤胶体颗粒,在电解质浓度较低时,它们的滑动层厚度差异显著;当电解质浓度较高时,它们的滑动层厚度之间差异不明显。When a colloidal particle carrying surface charge is dispersed in an aqueous solution, it adsorbs a large volume of ions, reverse in charge at its solid/liquid interface, thus forming an electric double layer （EDL） , which plays a vital role in ion sorption and desorption at the solid/liquid interface of charged colloidal particles and in stability of the colloidal particle suspension and stability of protein system According to the theory of the EDL model, a shear layer exists between the shear plane where Zeta potential （ ζ ） exists in the electric double 2ayer and the particle surface, and thickness of the shear layer is the distance between the shear plane and the particle surface. Thickness of the shear layer is not only an important physical parameter in the research on colloid and interface chemistry, hut also closely related with some electro-chemical properties, such as electrodialysis, electrophoresis, streaming potential and sedimentation potential. Nowadays, researchers commonly use the colloidal particle double electro layer model and DLVO theory in their studies on thickness of the shear layer and hold that the shear layer is very close to the Stern layer or the outer Helmholtz layer; and as thick as the diameter of about 2- 3 water molecules, about 0.5 nm, because they deem zeta potential approximate to the surface charge of colloidal particles. Meanwhile some researchers have figured out that the shear layer is 0.03 μm, 0.1 μm, 〈 0.25 IX m or no more than 2μm and believe that particle surface charge is infinite. And also some researchers have concluded through theoretical analysis that the shear layer is very closed to the Gouy plane in the electric double layer, however, its actual position is hard to determine. In light of the above described analyses, it is quite clear that the results the researchers obtained as to thickness of the shear layer vary sharply, mainly because it is very hard to measure accurately colloidal particle surface charge. In the colloid diffuse electro doub

关 键 词：滑动层厚度 恒电荷土壤 胶体颗粒 表面电位 ZETA电位 

分 类 号：X131.3[环境科学与工程—环境科学]