Genericity of confined chemical garden patterns with regard to changes in the reactants

Abstract

The growth of chemical gardens is studied experimentally in a horizontal confined geometry when a solution of metallic salt is injected into an alkaline solution at a fixed flow rate. Various precipitate patterns are observed-spirals, flowers, worms or filaments-depending on the reactant concentrations. In order to determine the relative importance of the chemical nature of the reactants and physical processes in the pattern selection, we compare the structures obtained by performing the same experiment using different pairs of reactants of varying concentrations with cations of calcium, cobalt, copper, and nickel, and anions of silicate and carbonate. We show that although the transition zones between different patterns are not sharply defined, the morphological phase diagrams are similar in the various cases. We deduce that the nature of the chemical reactants is not a key factor for the pattern selection in the confined chemical gardens studied here and that the observed morphologies are generic patterns for precipitates possessing a given level of cohesiveness when grown under certain flow conditions.

Direct and Reverse Chemical Garden Patterns Grown upon Injection in Confined Geometries

“…A zoom-in on a shell structure observed in the direct case as a possible structure other than the filaments is shown in Figure 3b for cobalt sulfate as the injected fluid. As it is generally the case in chemical gardens, 33 …”

“…32,33 Confinement in the thin gap of a horizontal cell 10 decreases the effect of buoyancy, whereas the use of injection limits the osmotic effects. Different patterns, generic with regard to changes in the chemicals, 33 have been observed when the concentrations are changed.…”

Filament dynamics in confined chemical gardens and in filiform corrosion

“…[14][15][16] In order to study their erratic growth, we perform image analysis. Each filament track is binarized and subsequently skeletonized as shown in Fig.…”

“…Such confined chemical gardens produce an array of morphologies, among which filaments are prominent. [14][15][16] The links between chemical gardens and certain types of corrosion are well established. Corrosion tubes are hollow tubular structures that have been noted and studied in iron corrosion under a variety of conditions.…”

Wavy membranes and the growth rate of a planar chemical garden: Enhanced diffusion and bioenergetics

“…The seed particle may be replaced by injected salt solutions (24). Furthermore, one can reduce the dimensionality of the system by the injection of salt solutions from a point-like source into a thin, horizontal layer of silicate solution contained within a Hele-Shaw cell (25)(26)(27). This approach was taken further by studying the formation of precipitate membranes in a microfluidic device at the planar interface between two parallel, cocurrent reactive fluid streams (28).…”