Study On Solubility Of Solid Solute In Supercritical Or Subcritical Fluids

Super(sub)-critical fluid has been widely used in the field of polymer preparation,extraction of the natural products and so on with its green chemical characteristics.Super(sub)-critical fluid phase equilibrium data,as an important property parameters,was used to provide support for the application of supercritical fluid technology.But the research of super(sub)-critical fluid phase equilibrium data is scarce.In this work,the dynamic method was used to measure the solubility of polystyrene(PS)with molecular weight of 100000 and 260000 g·mol-1 in the SCCO2 at the temperature(313,323 and 333 K)and pressure(from 9.0 to 18.0 MPa).The static method was used to measure the solubility of PS with molecular weight of 100000 and 260000 g·mol-1 in the sub-R134a at the temperature(313,323,and 333 K)and pressure(from 5.0 to 18.0 MPa).And the solubility of cinnamic acid in SCCO2,sub-R134a and SCCO2 with co-solvent(ethanol,ethyl acetate and n-pentane)at the temperature(308,318 and 328 K)and pressure(from 9.0 to 18.0 MPa).The influence of temperature,pressure and molecular weight of the solute to the solubility data were analyzed from the view of molecular micro level.In addition,the solubility enhancement factor(?)of the solute and the entrainment factor(?)in super(sub)-critical fluid was also calculated and analyzed.Six semi-empirical models(Chrastil,A-L,K-J,S-S,M-S-T and Bartle model)were applied to calculate the experimental solubility of PS and cinnamic acid in SCCO2 and subcritical R134a.And four semi-empirical models(Gonzalez,Sovova,Tang and Sauceau model)were used to calculate the experimental solubility of cinnamic acid in SCCO2 with co-solvent.The average absolute relative deviation(AARD)was also counted to show the precision of models.The partial molar volume of solute was calculated by K-J model.And the enthalpy values of solute,including ?OHtotai,?Hsub.and ?Hsol.were estimated through Chrastil and Bartle models.At last,the molecular association theory was used to deduce a new model which got used to calculated the solubility of solute in super(sub)-critical fluids.The 993 solubility data of this work and literature was used to inspected the new model,and the correlation resullts was improved campared with other models.The new model can be used to count the solubility of solute in the super(sub)-critical fluids.