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Abstract

Flow-driven precipitation experiments are performed in model porous media shaped within the confinement of a Hele-Shaw cell. Precipitation pattern formation and the yield of the reaction are investigated when borosilicate glass beads of different sizes are used in a mono-layer arrangement. The trend of the amount of precipitate produced in various porous media is estimated via visual observation. In addition, a new method is elaborated to complement such image analysis based results by titration experiments performed on gel-embedded precipitate patterns. The yield of confined porous systems is compared to experiments carried out in unsegmented reactors. It is found that the obstacles increase the amount of product and preserve its radial spatial distribution. The precipitate pattern is successfully conserved in a slightly cross-linked hydrogel matrix and its microstructure is examined using SEM. The spatial distribution of the precipitate across the cell gap is revealed using X-ray microtomography.

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... The resulting structures, often referred to as chemical gardens, can be seen as a simple example of self-organizing systems that exhibit all kinds of different morphologies under different chemical and physical conditions (37,38). Apart from precipitation and crystallization, structure growth is driven by fluid advection through either active injection (39)(40)(41)(42) or osmosis and convection (43,44). In the past years, they have also been increasingly studied in quasi-two-dimensional (2D) settings using microfluidic devices like Hele-Shaw flow cells (10,40,45,46). ...
... In the field of chemobrionics, confined quasi-2D flow setups (Hele-Shaw flow cells) are commonly used to study precipitation reactions and the resulting pattern formation. The experiments mostly use radial injection of the fluid (10,41,42,(45)(46)(47) rather than injection from one side as in our setting. Although we used different injections and chemical compositions, Rocha et al. (46) showed the formation of similar morphologies over the time of the experiment. ...
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... The resulting structures, often referred to as chemical gardens, can be seen as a simple example of self-organising systems that exhibit all kinds of different morphologies under different chemical and physical conditions [29,30]. Apart from precipitation and crystallisation, structure growth is driven by fluid advection through either active injection [31,32,33,34] or osmosis and convection [35,36]. In the past years, they have also been increasingly studied in quasi-2-dimensional settings using microfluidic devices like Hele-Shaw flow cells [32,37,38,39]. ...
... In the field of chemobrionics, confined quasi-2-dimensional flow-setups (Hele-Shaw flow cells) are commonly used to study precipitation reactions and the resulting pattern formation. The experiments mostly use radial injection of the fluid [37,39,38,33,34,40] rather than injection from one side as in our setting. Even though we used different injection and chemical composition, also e.g. ...
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