Electrophoretic mobility of colloidal gold particles in electrolyte solutions

Area of Science:

• Colloid and Surface Science
• Electrochemistry
• Nanotechnology

Background:

• Understanding colloidal particle behavior is crucial in various applications.
• Electrophoretic mobility is a key parameter for characterizing charged particles in suspension.
• Gold nanoparticles are widely used in diagnostics, drug delivery, and electronics.

Purpose of the Study:

• To investigate the electrophoretic mobility of gold nanoparticles in different electrolyte solutions.
• To determine the influence of electrolyte concentration and type on particle charge and zeta-potential.
• To analyze the electrokinetic behavior of gold nanoparticles using established theoretical models.

Main Methods:

• Measurement of electrophoretic mobility for five sizes of spherical colloidal gold particles.
• Experiments conducted in aqueous potassium chloride (KCl) and sodium phosphate solutions.
• Electrolyte concentration varied from 0.005 to 0.154 M.
• Analysis using the simplified electrokinetic formula by Ohshima.

Main Results:

• Measured mobilities were independent of electrolyte type but dependent on concentration.
• Effective electrokinetic charge density and total particle charge remained constant with increasing electrolyte concentration.
• A negative effective electrokinetic surface charge was observed in both KCl and sodium phosphate solutions.
• Zeta-potential exhibited a maximum absolute value in both electrolyte systems.

Conclusions:

• Electrolyte concentration significantly impacts the electrokinetic behavior of gold nanoparticles.
• The effective surface charge and total charge of gold nanoparticles are stable across varying electrolyte concentrations.
• Gold nanoparticles consistently display negative surface charge and zeta-potential in the studied electrolytes.