Electrophoretic mobility of a colloidal particle with constant surface charge density

Area of Science:

• Colloid and Surface Science
• Physical Chemistry
• Nanotechnology

Background:

• Electrophoretic mobility is commonly used to determine zeta potential.
• Zeta potential is concentration-dependent for particles with constant surface charge density.
• Surface charge density is a more characteristic property for such particles.

Purpose of the Study:

• To develop a systematic, non-computational method for determining the surface charge density of spherical colloidal particles.
• To provide an alternative to zeta potential calculations that are influenced by electrolyte concentration.
• To offer a more fundamental characterization of particle surface properties.

Main Methods:

• Derivation of analytical equations linking electrophoretic mobility, zeta potential, and surface charge density.
• Utilizing two key equations: electrophoretic mobility to zeta potential and zeta potential to surface charge density.
• Applying the method to experimental electrophoretic mobility data without numerical computer calculations.

Main Results:

• A direct, analytical method for calculating surface charge density from electrophoretic mobility was established.
• The method bypasses the need for complex numerical simulations or computer programs.
• Demonstrated applicability using existing electrophoretic mobility data for gold nanoparticles.

Conclusions:

• The proposed method offers a straightforward and accurate way to determine surface charge density.
• This approach provides a more intrinsic material property compared to the concentration-dependent zeta potential.
• The findings are valuable for characterizing and understanding colloidal and nanoparticle systems.