Electrochemistry/Colloid Chemistry Interaction: (a) Effect of Particle Size on Electrokinetic Phenomena and Coagulation; (b) Anodic Deposition of Colloidal Metal

Thermodynamic treatement of the problem of electrochemical potential of metal particles in the colloidal range leads to a · conclusion that the latter depends on particle radius. This phenomenon reflects also upon the electrokinetic potential of the colloids. Hence, in a polydisperse system particles are at different zeta- potential. The difference may be very significant towards the lower limit of the colloidal range. A quantitative treatement based on the Stern model of the electrical double layer shows the effect to be the strongest around the pzc and subsides towards high positive or negative potentials. As a result of this effect, the iso-electric point, rate of coagulation and electrophoretic mobility are also dependent on the particle radius. Deposition of metal from colloidal solution has also been investigated on the example of colloidal gold. It was shown that the negatively charged gold particles deposit at the anode