Aragonite crystallization in a Christmas-tree model microfluidic device with the addition of magnesium ions

Abstract

Aragonite is an important dimorph of calcium carbonate, industrially and biologically. However, aragonite is so thermodynamically unstable that it is difficult to understand its formation mechanism. A continuous microfluidic system was employed, in which crystallization was induced only by diffusion in a micron-scale channel. Calcium carbonate (CaCO 3 ) formed by liquid-liquid reaction and magnesium ions (Mg 2+ ) were used as additives. To assess the influence of Mg 2+ concentration, the Mg 2+ /Ca 2+ molar ratio was set to 1, 3, and 5. Laminar streams flowed in the detection channel with different concentration gradients. The initial crystallization time (t I.C ) increased exponentially and the density of crystals decreased as the Mg 2+ ion concentration increased. Following transformation of all particles into snowman or sphere shapes, they became spinose sphere-shaped crystals, which was the final form in this study.

Formation of Amorphous Calcium Carbonate and Its Transformation Mechanism to Crystalline CaCO3 in Laminar Microfluidics

“…Unraveling the fundamental mechanisms of calcium carbonate crystallization not only has great significance for understanding the mechanism of biomineralization, but also for developing its potential applications in encapsulation and drug delivery . However, more attention has been paid to research the effect of additives on the polymorphism and shape of calcium carbonate, − or more efforts have been devoted to the preparation of size or/and shape control of calcium carbonate crystals on microfluidic platforms. , Research on the environment phase of how to influence the crystallization process of ACC in microscale, and what new crystallization behaviors will appear when the crystallization process is completely diffusion-controlled, has not been investigated fully enough and further. As Matsuoka et al’s research revealed, the supercooled microflow can keep stable less than −20 °C in microchannels without freezing.…”

Aragonite and Its Composites: Preparations, Properties and Applications

“…Moreover, increasing the concentration of Mg 2 + ions reduced the required crystallization time for spinous sphere-shaped crystal formation. [75] Therefore, it can be inferred that different forms of aragonite crystals undergo a transformation process correlated to both magnesium ion concentration and reaction time.…”

“…(Copyright 2009 WILEY-VCH Verlag). From (F1) to (F4): Crystals obtained in micron-sized channels controlled by a continuous microfluidic system: (F1) Pentagonal-, snowman-, sphereshaped, and spinose sphere-shaped crystals observed for [Mg]/[Ca] = 3; (F2) magnified view of spinose sphere-shaped crystals; (F3) snowman-, sphere-, and spinose sphere-shaped crystals observed for [Mg]/[Ca] = 5; (F4) magnified view of sphere-shaped crystals [75]. (Copyright 2016, The Korean Society for Biotechnology and Bioengineering and Springer).…”

Lab on a chip for a low-carbon future

“…Microfluidic systems have been used recently to study carbonate precipitation 228,229 and they have shown a significant advantage over conventional experimental approaches by providing highly reproducible control over crystal polymorph, size, and shape. Therefore, future research should focus on developing frameworks for experimental design and data processing to determine the kinetics of CO 2 mineralization using desalination brine of various chemical compositions; one such approach is shown in Fig.…”