Formation of FeCl(2)/NaCl-nanoparticles in supercritical water investigated by molecular dynamics simulations: nucleation rates.

Nucleation and growth of FeCl(2) in supercritical water containing NaCl at different state points between temperatures of 798 and 873 K and system densities between 0.24 and 0.14 g cm(-3) have been studied by molecular dynamics simulations. The number of NaCl ion pairs was chosen to simulate particle formation in seawater and brine of higher salinity. Rigid SPC/E water was used to model the water molecules while a combination of Coulomb and Lennard-Jones potentials was used for the ions. Two different methods for determination of nucleation rates are applied and their results compared. We find decreasing nucleation rates with both increasing temperature and decreasing system density. Our results are also compared to those we recently obtained in an investigation of pure FeCl(2) from supercritical water. We find both increasing nucleation rates and a decreasing size of the critical cluster with increasing amount of NaCl.