Electrodeposition of particles at nickel electrode surface in a laminar flow cell

Electrodeposition of polystyrene particles on a nickel electrode was observed in the laminar flow cell. The efficiency (rate) of the electrodeposition was determined depending on flow intensity, electrode polarization vs. Ag/AgCl electrode and ionic strength of the solution. The negative polystyrene latex particles were turned positive by adsorption of cetyl trimethyl ammonium bromide (CTAB) and experiments were performed at fixed concentration of the surfactant. It was found that at the CTAB concentration 5×10−5 mol dm−3 mostly single particles were deposited. It was observed that during the experiment, particles were deposited at a constant rate, which well correlated with the electrode polarization and their zeta potential. When the experiments were performed at various flow conditions in the laminar flow cell, the rate of deposition was found only weakly dependent on the flow intensity. That indicated that the hydrodynamic blocking effects were negligible under conditions encountered in the experiment. It was confirmed by the simulation of the dependence of the hydrodynamic blocking on the shear rate in the simple shear flow. At higher concentration of CTAB 5×10−4 mol dm−3 and for the electrode polarization of −1.5 V (vs. Ag/AgCl), transient aggregation at the electrode surface was observed. Qualitative aspects of this aggregation are presented. When the electrode polarization was removed the aggregates moved away except the initial ones, which were firmly attached to the surface. The observed phenomena can be explained in terms of clustering of particles by electrokinetic flows.