Zeta Potential Studies of Titanium Dioxide and Silver Nanoparticle Composites in Water-Based Colloidal Suspension

We determine the zeta potential (ZP) by using electrophoretic laser light scattering and Laser Doppler Velocimetry (LDV). Particle sizes are measured by photon correlation spectroscopy (PCS). We studied the ZP for colloidal suspensions of TiO₂ and Ag metal particles in order to determine the kinetic interaction and charge exchange between the particles. We investigated the natural tendency of the particles for aggregation and varied the pH of the solution. It was found that the ZP versus pH curve for the mixed TiO₂/Ag did not behave as the average of the individual TiO₂ and Ag curves as one would expect, and instead there was a slight horizontal shift towards higher pH values which implies that the particles in the mixed TiO₂/Ag colloid are interacting with the result of charge exchange. The average particle size was measured in terms of effective diameter, for the TiO₂, Ag and the mixed TiO₂/Ag particles. The results indicated an increase of approximately 100 nm in the effective diameter of the mixed TiO₂/Ag particles size compared to the size of the individual TiO₂ particles. This can be explained as the fact that 50 nm Ag particles are adsorbed on the surface of the TiO₂ particles.