Synthesis of seawater-derived superhydrophobic calcium carbonate via CO2 mineralization by utilizing L-Arginine/L-Lysine oleate-based self-assembly structures

Superhydrophobic materials have been gaining popularity owing to their self-cleaning, anti-freezing, and anticorrosion properties. This study presents an approach for the synthesis of superhydrophobic calcium carbonate via CO 2 mineralization using carbon capture utilization (CCU) technology. By using biodegradable amino acids (L-arginine/L-lysine) and oleic acid, various biosurfactant self-assembly structures were formed as surfacemodifying agents of calcium carbonate owing to the saponification and lyotropic phase transition. Moreover, calcium cations were recovered from salt -farm wastewater using pH-swing ion separation for sustainability and waste management. we presented various self-assembly structures depending on the ratio of amino acids to oleic acid, such as spherical micelles, liquid crystal nanoparticles, and vesicles for L-arginine oleate and spherical micelles, cylindrical micelles, and planar lamellar structures for L-lysine oleate. The synthesized calcium carbonates were 87.95 % purified scalenohedral calcite under micellar L-arginine oleate and 87.08 % purified spherical calcite under micellar L-lysine. Moreover, their surface areas were 28.85 m 2 /g for L-arginine and 13.46 m 2 /g for L-lysine. They were significantly improved and larger than that of commercial calcium carbonate (3.45 m 2 /g). In comparison, larger agglomerated calcite particles were produced under the other self-assembled structures. During mineralization, the amount of calcium oleate adsorbed on the surface of calcium carbonate played a crucial role in particle formation. Notably, superhydrophobic calcium carbonates were synthesized with a contact angle of 168.66 degrees under spherical micelles of L-arginine oleate and 167.46 degrees under spherical micelles of L-lysine oleate. The in-situ surface modification method utilizing biosurfactant self-assembled structures was expected to revitalize the carbon capture and utilization.