tailieunhanh - Electrokinetics in a cylindrical capillary

Electrokinetic phenomena are induced by the relative motion between a fluid and a solid surface and are directly related to the existence of an electrical double layer with excess charges. In this work, we use a theoretical study of electrokinetics in a narrow cylindrical capillary to obtain the streaming potential and electroosmosis coefficients under the thin double layer assumption. | Lương Duy Thành và Đtg Tạp chí KHOA HỌC & CÔNG NGHỆ 190(14): 103 - 109 ELECTROKINETICS IN A CYLINDRICAL CAPILLARY Luong Duy Thanh1,*, Phan Van Do1, Pham Thi Thanh Nga1, Nguyen Trong Tam2, Pham Thi Na3, Phan Thi Ngoc3 1 Thuyloi University, 2Vietnam Maritime University, 3 University of Science - TNU ABSTRACT Electrokinetic phenomena are induced by the relative motion between a fluid and a solid surface and are directly related to the existence of an electrical double layer with excess charges. In this work, we use a theoretical study of electrokinetics in a narrow cylindrical capillary to obtain the streaming potential and electroosmosis coefficients under the thin double layer assumption. We use the obtained theoretical coefficients to compare with experimental data available in literature. The results show a good agreement between the theory and the experimental data and that validates the obtained model. The model for a narrow cylindrical capillary is a basis to understand electrokinetics in porous media. Keywords: electrokinetics, zeta potential, porous media, electric double layer, INTRODUCTION* Electrokinetic phenomena consist of different effects such as streaming potential, electroosmosis etc. When the pore fluid is mechanically forced to flow through a porous media, some of the excess charges are dragged to move, therefore causing streaming electric current in porous media, which is referred to as the streaming potential effect (SP). Conversely, an applied electric field forces the excess charges to move, therefore driving pore fluid flow, which is referred to as the electroosmosis effect (EO). Electrokinetics plays an important role in geophysical applications, environmental applications, medical applications and other applications. For example, SP measurement is used to detect subsurface flow in oil reservoirs or to monitor subsurface flow in geothermal areas and volcanoes. It is also used to detect seepage of water through retention structures such