化工进展2025，Vol.44Issue(3)：1706-1715,10.DOI:10.16085/j.issn.1000-6613.2024-0372
亚/超临界水中典型硫酸盐Na2SO4和K2SO4的溶解特性及机理
Dissolution characteristics and mechanisms of typical sulphates Na2SO4 and K2SO4 in sub-/supercritical water
摘要
Abstract
Supercritical water oxidation is an effective technology capable of efficiently and harmlessly treating toxic and complex organic wastes.However,inorganic salt solubility decreases dramatically near the critical point of water,and deposited salt can lead to reactor clogging,which has become a fundamental bottleneck for the large-scale application of this technology.Therefore,the dissolution characteristics and mechanisms of typical sulphates Na2SO4 and K2SO4 in sub-/supercritical water were investigated in this study.Na2SO4 and K2SO4 solubilities in water were obtained over a wider temperature and pressure range.It was found that the solubilities of Na2SO4 and K2SO4 increased about 8931 times and 36211 times in the water density range of 84.13-540.46kg/m3,respectively.The solubility of K2SO4 was higher than that of Na2SO4 under the same conditions.Solubility did not strictly increase with increasing water density.Na2SO4 solubility(64.375mg/L)at high density(215.18kg/m3 at 25MPa and 663.15K)was significantly 13 times lower than that(906.141mg/L)at low density(195.73kg/m3 at 21MPa and 643.15K).Because the former was in the supercritical state while the latter was in the subcritical state.The decreasing rate of solubility at 643.15-663.15K was much higher than that at 663.15-723.15K,which was consistent with the trend of water density and dielectric constant with temperature.Micro-mechanisms such as ion nucleation properties in the binary brine system of Na2SO4 and K2SO4 were revealed by molecular dynamics.Cl-had a lower charge/radius ratio than SO42-and SO42-with polyatomic ionic structure had more coordination layers than Cl-with monatomic,thus the solubility of chloride salts was higher than that of sulphate salts.Hydrated Na+,K+and SO42-ions could be formed at room temperature and pressure,and water molecules had a strong electrostatic shielding effect on salt ions.The electrostatic shielding effect was weakened under supercritical conditions,and ions collided and aggregated to form clusters,resulting in salt crystals.The results could provide a guidance for the further development of supercritical water technology.关键词
超临界水/硫酸钠/硫酸钾/溶解度/分子动力学模拟Key words
supercritical water/sodium sulfate/potassium sulfate/solubility/molecular dynamics simulation分类
资源环境引用本文复制引用
冯鹏,徐东海,何冰,刘欢腾,杨立杰,王攀,刘青山..亚/超临界水中典型硫酸盐Na2SO4和K2SO4的溶解特性及机理[J].化工进展,2025,44(3):1706-1715,10.基金项目
国家自然科学基金(22078258) （22078258）
西安交通大学青年拔尖人才支持计划(ND6J018) （ND6J018）
中央高校基本科研业务费(xtr052022009) （xtr052022009）
西安科学家和工程师团队建设项目(23KGDW0001-2023). （23KGDW0001-2023）
