Stabilization and destabilization effects of the electric field on stochastic precipitate pattern formation

Abstract

Stabilization and destabilization effects of an applied electric field on the Liesegang pattern formation in low concentration gradient were studied with numerical model simulations. In the absence of an electric field pattern formation exhibits increasingly stochastic behaviour as the initial concentration difference between the outer and the inner electrolytes ( Δ ) approaches to zero. Our numerical simulation results have shown that, if the electric field promotes the transport of the reaction front of the outer electrolyte into the diffusion column, then the electric field stabilizes the stochastic pattern structure. This means that Liesegang patterns in the simulations will be decreasingly stochastic, in terms of reproducibility of band locations and of the band formation. Destabilization behaviour was observed in the reverse case, if the electric field retards the diffusion of the outer electrolyte. Simulation of pattern formation is presented using concentration perturbations in a deterministic model. The precipitation process is based on ion-product supersaturation theory (Ostwald's model).