School of Civil Engineering, Beijing Jiaotong University.
●Contact Person: Dr. DU Saizhao（dusz@bjtu.edu.cn）
Speaker
ZHANG Guoping
(Prof.)
University of Massachusetts Amherst.
Department of Civil & Environmental Engineering.
01.Speaker IntroductionDr. ZHANG Guoping is currently a professor in the Dept. of Civil & Environmental Eng. at the University of Massachusetts Amherst, and had prior appointments at Louisiana State University and the University of Nottingham (UK). He obtained a Ph.D. from Massachusetts Institute of Technology in 2002, and an M.Eng. and dual B.Eng. degrees from Tsinghua Univ. (China) in 1994 and 1991 respectively. His research interests are divided into four major areas: green geopolymers and alkaline-activation for sustainability, nanomechanical and microscale characterization of clay-based geomaterials, hydrophobicity and surface modifications of minerals, and clay-biopolymer interactions. He has published more than 100 articles in a variety of journals and more than 50 conference proceeding papers.
02.Lecture OutlineThe electrical double layer (EDL), adopted by a plethora of disciplines (e.g., clay science, soil mechanics, electrochemistry, interface science, materials science, colloid chemistry), describes a nanoscale layer of electrolyte solutions (usually with water as the solvent) adjacent to a charged electrode (e.g., anode, cathode) surface, where the oppositely charged counter ions balance the net charges of the electrode. A unique feature is that the concentration of the counter ions decreases nonlinearly with the distance from the charged electrode surface, and hence EDL is often also termed “diffuse double layer (DDL)”, which has been used interchangeably with EDL. The word “double” means that the EDL consists of two distinct or distinguishable layers: (1) a so-called Stern or Helmholtz layer, where “the counter ions are bound, usually transiently (i.e., as exchangeable ions, such as cation exchange)”, and (2) a real diffusive layer where the counter ions diffuse away from the electrode surface, as indicated by the concentration of counterions decreases asymptotically to that of the bulk solution. Because clay minerals possess negative permanent charges on face surfaces and variable charges on edge surfaces, which can be treated as a microscale electrode, the original concepts and theories of electrode-based EDL can be applied to clay particles.
This webinar aims to report a summary review of the origins, concepts, and recent validations on the EDL on clay surfaces. In particular, the effects of clay mineral surfaces’ diversity, heterogeneity, and nanostructure (e.g., cavities in the tetrahedral sheet, broken bonds on edge surface) on the EDL behavior and structure are discussed, such as “inner sphere complexes”, “outer sphere complexes”, spillover of double layer, differences between interlayer complexes and EDL, and hidden EDL. Finally, interpretation of exemplary engineering phenomena is highlighted to reflect the essence and importance of understanding the EDL concepts and theories as well as the underlying sciences.
03.Course Introduction《Frontier of geotechnical engineering》 is an all English online course for foreign students from the Civil Engineering School of BJTU. Based on this course, a series of online academic public lectures are specially held. This course is also opened to the public. All interested students or researchers are welcome to attend FREE without any registration.
●Please refer to link below for more information regarding BJTU Series Online Academic Open Lectures:
https://mp.weixin.qq.com/s/yq7QzTz028ZoeI6jT783gQ
You are welcomed to follow our official wechat account for more info. (Geotechnical Department, Beijing Jiaotong University. “北交岩土”)【岩土工程新进展】
线上开放课程第六讲
Electrical Double Layer on Clay Surfaces: Origins, Concepts, and Phenomena●主办单位:北京交通大学 土建学院 城市地下工程教育部重点实验室
