Calcium Carbonate Particle Formation through Precipitation in a Stagnant Bubble and a Bubble Column Reactor
Calcium Carbonate Particle Formation through Precipitation in a Stagnant Bubble and a Bubble Column Reactor
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DOI：
10.1021/acs.cgd.0c00741
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发表时间：
2020-08-05
影响因子：
3.8
通讯作者：
York, David W.
中科院分区：
文献类型：
--
作者：
Grimes, Christopher J.;Hardcastle, Thomas;York, David W.
本研究使用明确的膜通过 CO2 鼓泡沉淀 CaCO3，以产生各种结构的颗粒。通过这种方法对颗粒形成机制的研究是有限的，并且主要针对中空结构。使用一系列分析技术，对静止气泡和鼓泡系统（横流和垂直流）中产生的颗粒进行了研究。停滞气泡工作得出的结论是，颗粒既大量产生，也在气/液界面产生，然后落下并收集在气泡底部，而在动态系统中，气泡尾流在此类颗粒的沉淀中起着重要作用。当二氧化碳鼓泡（酸性气体）导致溶液 pH 值下降时，会发生沉淀，这些颗粒最初由固体核心组成。随着 pH 值进一步下降，这些颗粒会转变为空心颗粒，并且 pH 值在控制颗粒壳厚度方面起着重要作用。允许颗粒在溶液中老化允许这些颗粒从球霰石转变为方解石。最后，还可以通过改变起泡设置来改变颗粒结构，因为具有再循环回路，导致形成呈现堆叠立方体的颗粒。
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.