Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 39: Colloids and Complex Liquids II - Dynamics and Mechanical Properties
CPP 39.8: Vortrag
Donnerstag, 17. März 2011, 12:15–12:30, ZEU 222
Force Measuments between colloidal Particles across aqueous electrolytes using CP-AFM — •Liset Luederitz and Regine von Klitzing — Stranski-Laboratorium fuer Physikalische und Theoretische Chemie, Institut fuer Chemie, Technische Universitaet Berlin, Strasse des 17. Juni 124, D-10623 Berlin
The interaction forces between two colloidal silica particles across different electrolytes, CsCl, KCl, NaCl and LiCl were measured using CP-AFM technique. In our study the adsorption of counterions follows the Hofmeister series for CsCl, KCl and NaCl but LiCl has anomalous behaviour. The instability of the hydration shell of lithium could be a reason for the observed anomaly. The DLVO theory explains the interactions between the colloidal particles assuming only two types of forces, repulsive electrostatic forces and attractive van der Waals forces. At short separation some deviations from the theory are reported [1]. These deviations are called non DLVO forces and are present in water and electrolyte solutions. In this work we measured short range attractions at 10−4M ionic strength whereas at 10−3M short range repulsions are observed. Another interesting phenomenon observed was the charge reversal with the studied monovalent ions at 10−3M ionic strength and low pH.
1. Valle-Delgado, J.J.; Molina-Bolivar, J.A.; Galisteo-González, F.; Galvéz-Ruiz, J.; Feiler, A.; Rutland, M.W. J. Chem. Phys. 2005, 123, 12.