A novel process for selective absorption of CO2/SO2 mixture gas with a single absorbent derived from seawater-based industrial wastewater

Herein, a novel method is proposed for selectively capturing SO2 and CO2 gases using a single absorbent derived from seawater-based industrial wastewater. The method is based on the thermodynamic properties of the absorbent, which produces a driving force for the preferential capture of SO2 over CO2 gas due to the difference in Gibbs free energy and formation enthalpy. Once SO2 and CO2 were captured in the aqueous medium, they were mineralized into calcium sulfate dihydrate (gypsum) and MgCO3, respectively. To enhance the industrial applicability of the final products, the crystallization properties of each precipitate, such as the particle size, crystallinity, polymorph, and purity were investigated at different ion concentrations in the aqueous suspension. The results demonstrated that the crystalline structures of both CaSO4 and MgCO3 are highly affected by the ion distribution in the aqueous medium, thus controlling the target structures. A higher saturation level leads to larger particle sizes via stronger agglomeration between crystallites. However, the residual calcium ion concentration inhibits crystal growth during MgCO3 nucleation; thus, the number of hydrates was controlled for each sample. We hope that this study provides a viable option for the scale-up of the carbon capture utilization and storage technology and an alternative carbon capture technique to address the limitations and viability of currently employed technologies.