Osmotic contribution to the flow-driven tube formation of copper–phosphate and copper–silicate chemical gardens

Abstract

We have produced hollow copper-containing precipitate tubes using a flow-injection technique, and characterized their linear and volume growth. It is shown that the ratio of the volume increase rate to that of pumping is constant independent of the chemical composition. It is also found that osmosis significantly contributes to the tube growth, since the inward flux of chemical species dominates during the precipitate pattern formation. The asymmetric hydrodynamic field coupled with the inherent concentration and pH gradients results in different particle morphology on the two sides of the precipitate membrane. While the tubes have a smooth outer surface, the inner walls are covered with nanoflowers for copper phosphate and with nanoballs for copper silicate.

Influence of microscopic precipitate structures on macroscopic pattern formation in reactive flows in a confined geometry

“…Such chemical character dependent tube permeability was also reported elsewhere for the comparison of copper phosphate and silicate chemical gardens. 24 To wrap up the macroscopic pattern characteristics, we conclude that significantly different patterns can be obtained even when applying the same experimental conditions (reactant concentrations, flow rate, gap width, etc.) if the chemical composition of the injected reactant solution is varied.…”

Magnetic‐Field‐Manipulated Growth of Flow‐Driven Precipitate Membrane Tubes

“…The copper(II)‐phosphate system has been extensively studied, and a phase diagram that maps compositions at which precipitate membrane tubes grow vertically at a constant rate has also been obtained . Such membrane structures have facilitated the determination of osmotic contribution during the tube growth, which also provides a procedure to compare the permeability of membranes composed of different chemical elements …”

“…[8] Such membrane structures have facilitated the determination of osmotic contribution duringt he tube growth, which also provides ap rocedure to comparet he permeability of membranes composed of different chemical elements. [9] Flow-drivenp recipitation patternsa re also investigated in horizontally and radially propagating systems. If the host liquid layer is sufficiently deep, buoyancy plays an important role in determining product properties, for example, the thermodynamically unstable polymorpho fagiven chemical compound can be synthesized.…”

High-speed tracking of fast chemical precipitations

“…Although even simple reaction-diffusion systems can produce precipitate structures with hierarchy, 15 flow chemistry may provide even more tempting possibilities. [16][17][18] Precipitation reactions performed under different flow conditions have been thoroughly investigated, and therefore the effect of different reactants [19][20][21] and enhanced buoyancy 22 and the role of physical parameters, such as oscillatory pressure change during injection 23 and permeability differences of membrane structures, 24 are understood. Also, the ion-mobility-dependent unidirectional thickening of 1D precipitate membranes is explained on the basis of the coupling of transport processes and precipitation reactions in a microfluidic channel.…”