Molecular dynamics simulations and spectroscopic study of the microstructural solvation shells, transport, and dielectric properties of the {K₂CO₃-H₂O} system at various concentrations

Understanding the behavior of potassium carbonate (K₂CO₃) in water is essential for improving its performance in various chemical and industrial applications. The physicochemical properties of K₂CO₃ aqueous solutions determine its reactivity, stability, and efficiency in processes such as CO2 capture and alkaline electrochemistry. In this study, we combined molecular dynamics simulations and spectroscopic experiments to elucidate the microstructural, dynamic, and dielectric behaviors of the {K₂CO₃-H₂O} system across concentrations ranging from 0.11 to 1.07 mol.kg^-1 at T = 298.15 K. The analyses reveal strong ion-water correlations, coordination changes within hydration shells, and concentration-dependent variations in ionic mobility and dielectric constant. Experimental FTIR and NMR measurements validated the simulated structures and provided deeper insights into the hydration mechanisms and ion-water interactions governing the dissolution and transport properties of K₂CO₃ in water.

Classical molecular dynamics simulations were performed using GROMACS 2020.6 with the CHARMM36 force field for ions and the SPC/E water model. Ionic interactions were modeled through long-range Coulombic and short-range Lennard-Jones potentials. Systems spanning 0.11-1.07 mol.kg^-1 were equilibrated for 100 ns in both NVT and NPT ensembles, followed by 100 ns production runs at 298 K and 1 bar using the PME algorithm for electrostatics. FTIR spectra were recorded on a Spectrum Two instrument in ATR mode over the 400-4000 cm^-1 range, and ¹³C NMR spectra were acquired using a JEOL 500 MHz spectrometer in D₂O, providing experimental validation of the simulation-derived structural insights.