Calcium Carbonate Particle Formation through Precipitation in a Stagnant Bubble and a Bubble Column Reactor

Abstract

The precipitation of CaCO3 via CO2 bubbling using well-defined membranes was used in this study to produce particles of a variety of structures. Studies into the mechanisms of particle formation via this method are limited and are mainly specific to hollow structures. Using a range of analytical techniques, particles produced with a stagnant bubble and in bubbling systems (crossflow and vertical flow) were investigated. The stagnant bubble work concluded that the particles are produced both in bulk but also at the gas/liquid interface which then fall down and collect at the base of the bubble, whereas in a dynamic system the bubble wake has an important role in precipitation of such particles. Precipitation occurs as the solution pH drops due to CO2 bubbling (acidic gas), and these particles are initially comprised of a solid core. As the pH drops further, these particles transform to ones with a hollow core and the pH plays an important role in controlling the particle shell thickness. Allowing the particles to age in solution allows for transformation of such particles from vaterite to calcite. Finally, the particle structure can also be altered by changing the bubbling set up as having a recirculation loop leading to the formation of particles exhibiting a stacked cube.

3D Printed Gas Distributor for Enhanced Production of CaCO3 via Bubbling Carbonation

“…As the pore size of the bubbling reactor increases, the size or the volume of the bubbles becomes larger, which reduces the gas–liquid interface area and the residence time of the bubbles. 29 , 36 This results in the increased time for the carbonation reaction. Figure 7 b shows the XRD patterns of CaCO 3 products under different conditions.…”

“…The time of the carbonation reaction gradually increases as the pore size of the gas distributor increases. As the pore size of the bubbling reactor increases, the size or the volume of the bubbles becomes larger, which reduces the gas–liquid interface area and the residence time of the bubbles. , This results in the increased time for the carbonation reaction. Figure b shows the XRD patterns of CaCO 3 products under different conditions.…”

“…22 − 28 It just needs a simple gas–liquid–solid three-phase reactor with low investment in equipment. The size of CO 2 bubbles 29 , 30 has a significant effect on the carbonization. The reaction temperature, 22 , 24 pH, 24 additive, 22 , 31 and the solution viscosity 24 also have influences.…”

“…Among them, the intermittent bubbling carbonation is a widely used method in industrial production of calcium carbonate. − It just needs a simple gas–liquid–solid three-phase reactor with low investment in equipment. The size of CO 2 bubbles , has a significant effect on the carbonization. The reaction temperature, , pH, additive, , and the solution viscosity also have influences.…”

Evaluation of Solidified Wastewater Treatment Sludge as a Potential SCM in Pervious Concrete Pavements

“…The span parameter is an additional parameter that shows the width of the size distribution and the volume-based size distribution is defined as: Span = (D 90 –D 10 )/D 50 . Span parameter indicates how far the 10 and 90 percent points are apart, normalized with the midpoint [ 35 , 36 ].…”