Naslov
50 Years of Fundamentals of the Homogeneous Charge Double Layer Model

Autori
Mirnik, Mirko

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Electrokinetic Phenomena '98, Theory, Methods and Applications, Proceedings, / Ribitsch, Volker - Graz : Universität Graz, 1998

Skup
Electrokinetic Phenomena '98, Theory, Methods and Applications

Mjesto i datum
Salzburg, Austrija, 14.04.1998. - 17.04.1998

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Double Layer Model

Sažetak
Charging reactions and electric potential functions of different double layer theories of typical colloidal systems are described graphically. The main emphasis is put on the description of the point charge double layer model and its theoretical postulates. The theoretical postulates are compared with experimental results published by many world laboratories. It is demonstrated that they all support the point charge double layer model. It is demonstrated that the Debye-Hückel length of ions fixed on the surface of particles is a multiple of the same length of the ions in the bulk of electrolyte. The dependence of the electrolytic mobility is inversely proportional to the radius of the ion atmosphere of the ions that are fixed oh the surface of colloidal particles. The functions “electrolytic mobility versus coagulating counter-ion concentration and its charge number” is described and compared with experimental plots of some inorganic sols and organic lattices. The dependence of the adsorbed amount of constituent ions, e.g., of I-, on fresh precipitates, e.g., AgI, is defined and the influence on their starting concentration and concentration of added electrolytes is demonstrated. It is proved that the aged AgI precipitates peptize under the influence of electrolytes and that the peptized particles coagulate under practically identical condition as the fresh precipitates. It is demonstrated that the coagulated AgI is an ideal counter ion exchanger of very low exchanging capacity. The exchanging concentrations depend on the charge numbers and on the concentrations of the exchanging ions. Using the light scattering technique the kinetics of coagulation of inorganic sols is demonstrated to be of the second order. Also, the dependence of the critical coagulation concentration on the constituent ion concentration, on its charge number and on the solvent composition is demonstrated. The single particle light scattering technique proves that lattices coagulate by the second order reaction mechanism. It is proved that the colloidal crystals are formed because of their extremely high charge per particle number and in the absence of any electrolytes. Their crystallographic form is either body or face centered cubic. It can not be hexagonal as it may be concluded from the hexagonal patterns of the microphotographs.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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