Integrated CO2 capture and mineralization: impact of biopolymers as crystal growth modifiers on calcium carbonate crystallization

Accelerated CO2 mineralization can utilize billions of tons of CO2 annually. However, its widespread use, especially in aqueous systems, is limited by the lack of profitable applications of the produced carbonates. This study examines the effects of CO2 injection rate, reaction temperature, ultrasonication, and biopolymers (gelatin, xanthan, pectin) as crystal growth modifiers during integrated CO2 capture and mineralization using arginine as a CO2 absorption promoter. Our findings indicate that varying the CO2 injection rate (0.1–0.9 L/min) has minor improvements in Ca2+ conversion to CaCO3, with the Ca2+ to CO2 absorption promoter ratio being the primary factor. Higher CO2 injection rates resulted in smaller crystal sizes, while increased reaction temperatures improved Ca2+ conversion to CaCO3 and reduced vaterite content. Ultrasonication produced smaller (0.39 ± 0.07 μm), spherical porous vaterite particles. Gelatin caused excessive foaming, while xanthan led to particle agglomeration. Pectin yielded the best results, producing well-separated, homogeneous spherical vaterite particles. The consistent production of well-dispersed spherical porous CaCO3 particles through aqueous CO2 mineralization under ambient conditions paves the way for their high-end applications in industrial contexts.