Related Experiment Video
Updated: Jul 15, 2026

Creating Sub-50 Nm Nanofluidic Junctions in PDMS Microfluidic Chip via Self-Assembly Process of Colloidal Particles
Published on: March 13, 2016
Charging mechanism in colloidal particles leading to a linear relation between charge and size
Filip Strubbe1, Filip Beunis, Matthias Marescaux
1Ghent University, Electronics and Information Systems, Sint-Pietersnieuwstraat 41, Ghent B-9000, Belgium. filip.strubbe@elis.ugent.be
Abstract:
Colloidal particles that are dissolved in a liquid can become charged by preferential adsorption or dissociation of surface molecules. The assumption of a constant surface charge density leads to a particle charge that is proportional to the square of the radius. Recent experiments however have shown that in a number of cases the charge is linearly proportional to its size. We present a simple model for the charging of colloidal particles leading to a linear relation between charge and size in the framework of the mean-field Poisson-Boltzmann theory. The model is based on preferential adsorption or dissociation of surface molecules, in combination with a large concentration of chargeable surface sites. The model also predicts a surface potential that is independent of the particle size. Numerical simulations show that this model is in good agreement with analytical approximations.
Related Concept Videos
Colloidal precipitates
The Colloidal State
Continuous Charge Distributions
The electric charge can also be subjected to an analogical...
Coulomb's Law
Newton's third law applies to the Coulomb force — the force on...
Factors Affecting Activity Coefficient
The activity coefficient value for an ion is close to one when the solution has almost zero ionic strength, i.e., when the solution shows close to ideal behavior. As the ionic strength of the solution increases from 0 to 0.1 mol/L, a decrease in the...
Precipitate Formation and Particle Size Control
The obtained precipitate should be either a pure substance of known composition or easily converted to one by a simple process, such as ignition or drying. In addition, the precipitate should be insoluble and easily filterable. In general, filterability...

