Spontaneous classification of functional fine particles by dynamics of the precipitation bands

Abstract

When an outer electrolyte diffuses into a gel containing an inner electrolyte, rhythmic patterns of precipitate are formed, which is known as the Liesegang phenomenon. The patterns are static and stationary in the sense that the formed precipitation objects stay at the given position. Dynamically changing precipitation patterns can be formed if the complex formation of precipitate is possible. In this study, spontaneous appearance of traveling waves, spiral formation and chemical turbulence of precipitation bands is reported. The formation of spatiotemporal patterns allows us to spontaneous classification of fine particles because size distribution of particles varies with location. We investigated the effect of the inner electrolyte and gel concentrations on morphology of precipitation bands.