Towards green carbon capture and storage using waste concrete based seawater: A microfluidic analysis

Carbon capture and utilization technology is the research stream dedicated to mitigating the pressing effect of rising atmospheric carbon dioxide (CO2). The present study investigates a potential environmentally conscious solvent to capture and utilize CO2 using waste concrete and seawater under reactor conditions. Although seawater's CO2 soubility is low due to salinity, waste concrete raises seawater's pH and alkalinity, acting as a feedstock for CO2 dissolution and offsetting the adverse effects of salinity. To evaluate the performance of the novel natural seawater-concrete solutions for CO2 capture, time-dependent pH changes of solutions exposed to CO2 were measured in a microchannel using fluorescence microscopy. The concentration of dissolved CO2 in the solution was derived from pH change, revealing a 4-fold increase in the total dissolved carbon from 0.034 to 0.13 M and a 57.54% increase in the CO2 dissolution coefficient from 530 to 835 μm2/s in seawater upon concrete addition. Electrolysis further enhanced the CO2 capture capacity of the seawater-concrete solution by increasing the pH, enabling the solid precipitation of carbonate minerals. Raman spectroscopy and scanning electron microscopy showed that electrolysis-driven precipitates are mainly amorphous calcium carbonates, useful building blocks for seashells and coral reefs.

Experimental study on the dissolution of supercritical CO2 in PS under different agitators

In the continuous molding of microporous plastics, the polymer/CO2 homogeneous body needs to be formed in a very short time, which affects the subsequent bubble nucleation, bubble pore distribution, and growth, and is the key to the molding. It is known that the formation time of homogeneous body is shortened during the continuous molding of microporous plastics because of the agitator’s effect. However, different agitators have different effects on the dissolution rate. So, it is necessary to study not only the dissolution of gas in polymer melt under static condition but also the dissolution under the action of the agitator. In this article, the solubility and dissolution rate of supercritical CO2 in polymer melt PS at different temperatures and pressures were experimentally investigated under conical and screw agitators, and the numerical solution was also carried out.