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 friendly solvent to capture and utilize CO2 using waste concrete and seawater under reactor conditions. Although seawater’s CO2 solubility 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 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 and a 53.3% increase in the CO2 dissolution rate in seawater upon concrete addition. Electrolysis further enhanced the CO2 capture capacity of the seawater-concrete solution by increasing pH, enabling 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