Intensification of the carbonation process, in which CO$_2$ is absorbed into an alkaline solution, represents a promising pathway for carbon capture and utilization. The main limitation of this process is the slow mass transfer caused by the low solubility of CO2 and limited interfacial area. The aim of this thesis was to develop and characterize an experimental ejector-based system capable of generating dense dispersions of microbubbles, thereby significantly increasing the interfacial area and enabling accelerated mass transfer.
The experimental setup was based on Carmin D2 ejector, a syringe pump, and a PDMS microchannel. The system was characterized by studying the effects of volumetric flow rate (1000–3000 μL/min) and the concentration of the nonionic surfactant Tween 20 (0-20 ppm) on bubble size, distribution, stability and density. For quantitative analysis, an automated protocol with two specialized macro codes was developed in ImageJ.
The results showed that increasing flow rate increased bubble size and their density up to 155 bubbles/mm$^2$. The addition of surfactant had a decisive effect, at only 10 ppm Tween 20, the number of stabilized bubbles at the highest flow rate increased by a factor of 4,6 (from 129 to 594) enabling surface coverage of up to 10 %. Time-resolved analysis confirmed that the surfactant effectively prevents coalescence, while Ostwald ripening remains the main destabilization mechanism.
In conclusion, the developed ejector-based system reliably generates dense microbubble dispersions in a microchannel and achieves a high specific interfacial area. The system shows strong potential for the intensification of the processes where mass transfer is the limiting step, such as carbonation, and provides a solid basis for further application-oriented research.
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