| 摘要: | 在本研究中，利用兩種預測型的熱力學模型來計算固體溶質於超臨界二氧化碳中的溶解度，分別為官能基貢獻法的PSRK狀態方程式，及透過量子化學進行運算的PR+COSMOSAC狀態方程式。因於PSRK狀態方程式的計算中，需使用純物質的臨界性質，於是另外找了四種官能基貢獻法分別為JR、CG、MG和NRR，以及PR+COSMOSAC狀態方程式來計算其所需的臨界性質。而PR+COSMOSAC只需要分子結構，並利用該結構進行量子化學與COSMO溶合計算的結果，不需要其他的輸入檔，即可計算流體的相平衡。最後利用固體溶質的熔點及熔化熱計算固相的逸壓，並透過熱力學相平衡的計算，即可得到固體溶質於超臨界二氧化碳中的溶解度。
為了系統性的比較此兩種方法於溶解度計算的差異，本研究一共探討了101個固體溶質於超臨界二氧化中的溶解度，由於PSRK會有缺乏官能基定義及參數的問題，故PSRK僅能計算其中59個系統，以不同臨界性質的計算結果分別表示為PSRK-JR、PSRK-CG、PSRK-MG、PSRK-NRR及PSRK-PRCS，其誤差(ALD-x)分別為1.962、1.410、1.346、1.468及1.468，然而在同樣的59個系統中，藉由PR+COSMOSAC計算所得到的誤差(ALD-x)為1.003，且因PR+COSMOSAC無缺乏參數的問題，故可應用於預測本研究中的101個系統，而其溶解度預測之誤差(ALD-x)為0.921，亦有良好的表現。本研究進一步從中挑選出23種固體溶質，探討其與20種有機共溶劑及超臨界二氧化碳混合的三元系統，一共組合出61個系統，利用PR+COSMOSAC進行溶解度的預測，其結果顯示計算誤差(ALD-x)為0.719，亦具有一定的準確度，而PSRK因缺參數的緣故，僅能計算其中53個系統，利用PSRK-JR、PSRK-CG、PSRK-MG、PSRK-NRR及PSRK-PRCS進行溶解度的預測，誤差(ALD-x)結果分別為1.800、1.299、1.372、1.342及1.384。
;In this study, two predictive thermodynamic models were applied to predict the solubility of pure solid solute in supercritical carbon dioxide. One is the PSRK EOS (Predictive Soave-Redich-Kwong equation of state) and the other is the PR+COSMOSAC EOS. The PSRK EOS is based on the group contribution concept. The required critical properties and acentric factor of pure solid solute for PSRK EOS are also determined from group contribution methods (four different models are evaluated: JR, CG, MG and NNR) and PR+COSMOSAC EOS, due to the absence of experimental data in literature. The PR+COSMOSAC EOS utilizes quantum mechanical calculation results of molecules to predict phase equilibrium of fluids and does not required critical properties and acentric factor as input. However, it should be noted that the melting temperature and heat of fusion of solid solutes are necessary to estimate the solid phase fugacity in the solubility calculation for both EOS.
The solubility of 101 solid solutes in supercritical carbon dioxide is investigated in this study. Because of the missing parameter issue and lack of functional group definitions in group contribution methods, the PSKR EOS can predict solubility for only 59 solid solutes. The overall average logarithmic deviation (ALD-x) in solubility for these 59 solid solutes are 1.96, 1.41, 1.35, 1.47, 1.47 and 1.00 from PSRK-JR, PSRK-CG, PSRK-MG, PSRK-NNR, PSRK-PRCS and PR+COSMOSAC, respectively. The PR+COSMOSAC EOS, in general, provides more accurate results than group contribution methods. Since the PR+COSMOSAC EOS does not have the missing parameter issue, it can be applied to predict all solid solutes considered in this study and provide a similar accuracy (ALD-x = 0.92). In addition, the accuracy of six aforementioned approaches in predicting solubility of 23 solid solutes in supercritical carbon dioxide with 20 organic cosolvents (a total of 61 ternary systems) was also investigated. The PR+COSMOSAC EOS still provides the most accurate results (ALD-x = 0.71) in the ternary systems compared to those from PRSK EOS (ALD-x = 1.87, 1.32, 1.39, and 1.82 from PSRK-JR, PSRK-CG, PSRK-MG, and PSRK-NNR, respectively, for 18 solid solutes and a total of 53 ternary systems). This study shows that the PR+COSMOSAC EOS could provide useful information for design of industry process when no experimental data are available. |
