超臨界流體分離技術乃利用溶質在超臨界流體中較大的溶解度的變化來進行，而影響固體溶解度的因素除了溫度、壓力外，共溶劑的添加亦有可能，因此，欲發展此一分離製程，則固體在超臨界流體中的溶解度實驗數據及一個可以準確預測相行為及計算溶質溶解度的熱力學模式是主要的關鍵所在。本研究以一套半流動式的高壓相平衡實驗裝置在溫度313.15 K~333.15 K以及壓力15 MPa~28 MPa(150 bar~280 bar)的條件下量測單一β-胡蘿蔔素以及在丙酮、乙醇、正己烷等共溶劑參與下β-胡蘿蔔素在超臨界二氧化碳中的平衡溶解度數據。對於熱力學模式的關聯，選用Peng-Robinsion狀態方程式(PREOS)並配合VDW2混合律，此外，本研究將嘗試幾種以流體密度或無限稀釋溶液理論為基礎的半經驗及其修正模式如Chrastil、Mendez-Santiago和Jiang等，來探討共溶劑濃度對β-胡蘿蔔素溶解度的影響，希望能提供進一步分離程序設計時所需之最適熱力學計算模式。
The solubilities of β-carotene in pure supercritical carbon dioxide with, respectively, the cosolvents of ethanol, acetone, and n-hexane were measured using a semi-flow type apparatus and ranged from 15 MPa to 28 MPa under a temperature range of 313.15 K to 333.15 K. With regard to the experimental solubilities in pure supercritical carbon dioxide, the data are consistent with values reported in the literature with a magnitude order from 10^(-8) to 10^(-7) in mole fraction. The experimental results showed that the cosolvents increased the solubility, and the effect in the order of acetone >n-hexane >ethanol with exceptions under some experimental conditions as described in the paper. The largest enhancement in the solubility by a cosolvent appears at 333.15 K, 15 MPa with 10% n-hexane in the solvent mixture. The experimental solubility data of β-carotene in CO2 were correlated fairly well with the Peng-Robinson equation of state incorporated with the modified van der Waals mixing rule, and with the method of Debenedetti and Kumar. The experimental data of β-carotene+CO2+ethanol, β-carotene+CO2+acetone, and β-carotene+CO2+n-hexane systems were correlated with the modified empirical equation of Chrastil.
關聯:
Journal of the Chinese Institute of Chemical Engineers, Vol.37 no.4, pp.329-339
