Ternary deep eutectic solvent-mediated one-pot solvothermal synthesis of biocarbon sheet-supported La2(CO3)3 nanowire with antibacterial activity for advanced phosphate adsorption

Biocarbon-supported lanthanum-based materials have garnered extensive attention in phosphate adsorption. Among diverse La species, lanthanum carbonate (LC) possesses balanced properties in phosphate affinity, biocompatibility, and stability. However, direct one-pot synthesis of positively charged biocarbon and simultaneous assembly of LC on the biocarbon is challenging. Herein, a ternary deep eutectic solvent (DES) composed of glucose, urea, and LaCl₃ was applied as the precursor and medium for the one-pot solvothermal synthesis of biocarbon sheet (BCS)-supported La₂(CO₃)₃ nanowire (BCS-LC). The as-prepared BCS-LC possesses a 2D lamellar structure with dispersed La₂(CO₃)₃ nanowire. The as-prepared BCS-LC is highly efficient in removing phosphorus from biogas effluent (from 83 to < 0.05 mg/L, around 99.9% removal) and natural pond water (from 5.1 to < 0.05 mg/L, > 99% removal) at 1 g/L dosage, which is superior for phosphate adsorption from practical solutions with complex co-existing substances or low phosphate concentration. The phosphate adsorption by BCS-LC is dominated by ligand exchange-induced inner-sphere complexation. DFT calculations further validate the favorable role of nitrogen-containing functional groups on the biocarbon sheet for enhancing affinity to phosphate anions. Furthermore, attributed to the nanowire morphology of LC, the as-prepared BCS-LC is high-efficient in inactivating S. aureus (with a 99.99% antibacterial rate) in the solution. Finally, this study developed a novel strategy by using the ternary DES as the precursor and medium for the synthesis of lanthanum-based adsorbent with antibacterial activity for advanced phosphate adsorption.