Fig. 1
Experimental setup, Raman spectra, and snapshots of experimental result. (a) A detailed view of the inlet side consisting of two inlets (blue arrow: \(\text {CaCl}_{2}\) and orange arrow: \(\text {Na}_{2}\text {CO}_{3}\)) dedicated for injection of aqueous solutions and two channels (red arrows) for oil circulation. The purple box shows the location where monitoring was performed to ensure well mixing the reactants at the nozzle. Several droplet traps are installed on the storage platform to trap the droplets during the monitoring process. The unlabelled channels are not used during the experiments, denoted by X marks. (b) Raman spectra confirming the three different phases and their associated morphologies, with the spectrum of the oil in the reactor shown in cyan. (c) Snapshot of the droplet storage channel after 40 minutes, with droplets numbered 1-11 indicating presence of crystalline phases. (d) Snapshot of the droplet storage channel after 360 minutes with additional droplets numbered 12-20 on top of the ones in (c) where ACC has transformed into crystalline phases. (e) Zoomed-in view of the yellow box (\(800\,\upmu\)m width) from (d), providing better visualization of the calcium carbonate phases: ACC phase (irregular shape), vaterite crystal (spherical shape), and calcite crystal (rhombohedral shape).
