Experimental and molecular dynamics simulation study on solubility characteristics of chloride and sulfate salts in supercritical water

Supercritical water gasification (SCWG) shows great potential in converting organic waste into hydrogen-rich gas with low environmental impacts and significant economic benefits. However, a comprehensive analysis of the solubility of inorganic salts in supercritical water is still scarce, hindering the application of SCWG high-salt organic waste. In this work, solubility characteristics of chloride and sulfate salts in the range of 673 K to 773 K and 22 MPa to 30 MPa are explored using both experimental and molecular dynamics simulation methods. The results indicate that salt solubility in supercritical water increases with decreasing temperature and increasing pressure. The solubility of cations and anions follows the order of K⁺ > Na⁺ > Ca²⁺ and Cl^- > SO₄^2-, respectively. The addition of type I salt significantly enhances type II salt solubility in the ternary system. This work is expected to offer a reference for the optimization design of SCWG reactors.