Molecular Dynamics Study on the Nucleation Characteristics of Mixed Na₂SO₄/K₂SO₄ Solution in Supercritical Water

Nucleation properties of mixed Na2SO4/K2SO4 solutions were investigated by molecular dynamics simulations. In the mixed solution, ions were attracted to each other and collided to form ion pairs or small clusters, and deposition occurred after further collisions up to a certain scale. The radial distribution function, hydrogen bonding, PMF curves, and coordination number indicated that K+ had a stronger ability to attract water molecules, and in the presence of K+, water molecules in the vicinity of Na+ were decreased, and the probability of collision between Na+ and SO42– ascended. This accelerated the deposition of Na2SO4. The deposition mechanism in the mixed solution was summarized based on the simulation results. It was also found that the nucleation of Na2SO4 was more sensitive to temperature and that of K2SO4 was more sensitive to concentration in the mixed solution.