Precipitation of CaCO3 through induced mixing and its impact on solute breakthrough

Calcium carbonates precipitation plays an important role in several geological, biogeochemical and engineered processes. It has been extensively studied for its application in remediation of contaminated groundwater, enhancing oil and gas recovery, improving geological carbon storage, reducing leakage in tunnel buildings and also to understand dissolution processes in coastal karst aquifers. Most of these works are based on theoretical formulations,  numerical simulations or batch/column experiments and little experimental evidence under transport conditions are reported in the literature. In this work through mixing-induce precipitation experiments we propose the visualization and characterization of the dynamic of precipitation processes focused on the understanding of its influence in solute breakthrough. We performed the experiments in a transparent horizontal cell flow made of plexiglass with 26 x 20 x 1 cm dimensions. The tank was disposed horizontally and filled with glass beads of 2 millimeter. The flow-cell was initially saturated with double-deionized water. In the experimental investigation, two different chemical solutions containing 0,1 M CaCl₂ and 0,1 M NaCO₃ were injected in two separate inlet ports. Color tracer tests consisted on fluorescein were injected before and after the precipitation experiment with the objective of visualizing and quantifying the impact of precipitation in solute transport. We evaluated the effectiveness of the standard solute transport equation to represent precipitation processes and developed new mechanistic transport models.