Molecular dynamics simulations on salt deposition and nucleation in supercritical water

Supercritical water oxidation (SCWO) can be used as an efficient and environmentally friendly method to dispose organic wastewaters. However, salt deposition is typically encountered during SCWO treatment, so severely hindering its commercial application. This work presents a systematic and comprehensive summary of the solubility and deposition characteristics of inorganic salts under supercritical water conditions. The dissolution characteristics of inorganic salts in supercritical water and their general trends are summarized, and the effects of changes in salt phase behavior with temperature and pressure, and salt interactions on deposition characteristics are also examined. Molecular dynamics simulations show that deposition microscopically manifests itself as aggregation and growth of particles. The key to deposition lies in the number of small and medium-sized clusters that eventually form, with larger numbers being more difficult to deposit and more soluble.