SISTEM CO2-ETANOL DALAM BENTUK GAS-EXPANDED LIQUID (GXL) SEBAGAI PELARUT UNTUK EKSTRAKSI SENYAWA XANTHONE DARI KULIT MANGGIS

CO2-eXpanded Liquid (CXL) has been known as a promising system in various applications. In this research, CO2 gas is introduced to Ethanol to form CO2-expanded Ethanol and used as a solvent to extract xanthone from mangosteen fruit rind. Ethanol was mixed with mangosteen fruit rind powder at ratio 5:1 (v/wt) and then CO2 was introduced at various pressures (0.50 MPa to 5.25 MPa) at room temperature for 24 hours until reach its equilibrium state. Xanthone which dissolved in ethanol were obtained from the extraction apparatus as CO2 degassed out from the system. Quantitative analysis method was developed by using High Performance Liquid Chromatography (HPLC) containing methanol:water as mobile phase to determine number of xanthone extracted at various pressures. Number of CO2 disolved in ethanol was calculated theoritically using Peng-Robinson EoS and UNIQUAC Excess Gibbs Energy equation by assuming that the system was in binary composition of ethanol-CO2. Thermodynamic analysis was carried to predict the non-ideality (activity coeficient) of the xanthone solubility in etanol-xanthone-CO2 system by using Two-Suffix Margules, Van Laar, Three-Suffix Margules, and UNIQUAC (Model I, II, III, and IV) equation of Excess Gibbs Energy. Xanthone solubility in CO2-expanded Ethanol is reaching its maksimum point (1.3380x10-05) at 2.80 MPa pressure or at 0.3272 mol fraction of CO2 disolved in ethanol. Thermodynamic binary parameters for each model were predicted by using Sum Square of Error (SSE) by fitting experimental data into the models. Activity coefficient of xanthone was obtained at 303 K at various pressure, 3,040.86 � 6,151.86 (model I), 2,765.21 � 5,966.26 (model II), 2,757.37 � 6,050.47 (model III), and 2,996.19 � 6,067.50 (model IV), while the lowest SSE was occurred by using van Laar eqution (Model II)