Youn Yong Lee

Phase equilibria for carbon dioxide-ethanol-water system at elevated pressures

Abstract For applications related to the use of supercritical C02 to concentrate ethanol solutions from a fermentation broth, vapor-liquid equilibria for the CO 2 C 2 H 5 OH and the CO 2 C 2 H 5 OHH 2 O system were measured at 313.2, 323.2, 333.2, and 343.2 K at pressures up to 18.5 MPa over a wide range of ethanol concentration. A circulation type of equilibrium apparatus in which both vapor and liquid phases were continuously recirculated was adopted for measurements. Using C02, aqueous ethanol can be concentrated above atmospheric azeotropic composition (89.4 mol %) when the pressure in the ternary system CO 2 C 2 H 5 OHH 2 O is below the critical pressure of the binary system CO 2 C 2 H 5 OH. The experimental measurements for the phase equilibria were compared with the results predicted by Patel-Teja equation of state using each one of the four types of mixing rules: conventional, Wilson, Yu et al., and Adachi and Sugie. Good estimation was obtained for the phase equilibria of the binary systems except for the conventional mixing rule. It was also found that the phase behavior of the ternary system can be better predicted by the Patel-Teja equation of state with the Adachi and Sugie mixing rule than with the three other mixing rules, though the concentration is not estimated satisfactorily.

Mass-transfer and hydraulic characteristics in spray and packed extraction columns for supercritical carbon dioxide-ethanol-water system

Abstract Mass-transfer efficiencies and hydraulic characteristics of a 3.18-cm spray and a packed column for extracting ethanol from aqueous ethanol solution with supercritical carbon dioxide were investigated. Experiments were performed at 308.2, 313.2, and 323.2 K over a pressure range from 9.1 to 12.2 MPa. The influences of fluid properties, phase flow rates, column internals, and phase dispersion on mass-transfer efficiencies and hydraulic characteristics are discussed. An extension of a model for predicting mass-transfer efficiency in conventional liquid-liquid extraction to supercritical-fluid extraction was attempted. The model for mass-transfer efficiencies, developed for conventional spray and packed liquid-liquid extraction columns, was in good agreement with our experimental results.

Extraction of Perillyl Alcohol in Korean Orange Peel by Supercritical CO2

Supercritical fluid extraction (SFE) in a pilot plant was carried out to extract perillyl alcohol (POH) from Korean orange peel. The extract from the powder of Korean orange peel was obtained by supercritical CO2 at operating conditions of 50°C, 200 bar, and 6 CO2 kg/h/kg sample. Most of the POH was extracted within 14 hours in the experiment. The yield of extract containing POH was 2.5% based on the dry powder of the orange peel. The content of POH in the extracts was 2.8 × 10−3 (wt%) by GC analysis based on the dry powder, which indicated that SFE was approximately 30 times more efficient than the solvent-extraction method previously reported. A brief comparison of SFE and solvent extraction was made. The SFE extracts were further purified by open tubular chromatography to confirm POH in the extracts.

Fast determination of Langmuir isotherm parameters in large concentration of one solute

A simple method is presented to obtain the Langmuir isotherm parameters. Although this method is limited to the case of large concentration, a few injections enable the determination of the parameters. For a sample of thymine, with the injection volumes of 1.0 and 1.5 ml, the parameters of a and b are determined as 15.83 ml/ml and 0.12 ml/mg, respectively.

SUPERCRITICAL FLUID EXTRACTION OF PERILLYL ALCOHOL IN KOREAN ORANGE PEEL

A series of experiments for supercritical fluid extraction (SFE) were carried out to extract the perillyl alcohol (POH) from Korean orange peel. The yield of extract from the Korean orange peel powder was investigated under the temperatures of 30–60°C, the pressures of 150–200 bar, and the CO2 flow rates of 1.5–3.5 L/min. It was found that the yield of SFE extract containing POH was obtained as 1% of the dry powder of the orange peel. By GC-analysis of the peel oils obtained by SFE in the experimental ranges, the content of POH was 2.8 × 10−3 (%, wt.) based on the dry powder, which indicated that SFE was approximately 30 times more efficient than the solvent-extraction method previously reported. The SFE-extracts were further purified by gravity-flow packed column chromatography to confirm POH in the extracts.

Effect of sample sizes on peak shapes in preparative liquid chromatography

Cyclobutane pyrimidine dimers and monomers of thymine were separated on a C18 reversed-phase high performance liquid Chromatographic column. Using the two mathematical models, the effect of the sample sizes on peak shapes in preparative liquid chromatography was investigated. One of them is the linear kinetic model, and the other is based on the nonlinear adsorption isotherm. In case of small injections of sample, the good agreements between the calculated value by the linear kinetic model and experimental data were achieved. However, when sample size is increased, this model lacks in the prediction of large concentration profile of sample. However, the nonlinear model permits the accurate prediction of the location of the component ▪ band and the determination of the appropriate time to start and stop collection of the enriched fraction at the higher concentrations of monomer and the lower that of dimer. Therefore, extremely small amounts of dimer can be extracted from monomer solutions.

Simulation of the combined continuous and preparative separation of three close-boiling components in a gas-liquid chromatography

The combined continuous and preparative gas-liquid Chromatographic system was considered for separating continuously three close-boiling components, diethylether, dimethoxymethane, and dichloromethane. Their concentration profiles were simulated by the methematical model, which assumed the uniform distribution of stationary liquid phase and the linearity of the equilibrium isotherm.The operational principles of the system are that the least-absorbed component of the three components can be obtained purely before the elution of the most-absorbed components if the mixture is continuously injected into the one of the two sections (partition section) and at the same time, in the other section (desorption section), the three components remained in the column can be separated by the adjusting the experimental conditions and the column configuration. If the operations in the two sections are simultaneously finished within a time (switching time), continuous separations of the three components are feasible. The effect of the various operating conditions on the resolution is investigated. From the results of the simulations, the resolution is greatly affected by the additional column length in the desorption section and the switching lime can be determined by the desorbenl velocity.

Separation of close-boiling components by the combined continuous and preparative chromatography: Comparison of experimental data with calculated values in binary system

Operational characteristics of the combined continuous and preparative gas-liquid Chromatographic system were investigated for the separation of two close-boiling components, diethylether and dichloromethane. It was experimentally confirmed that the additional column length and the desorbent velocity were the most important factors to ensure the continuous separation of the feed mixture.The theoretical concentration profiles derived with the assumptions of the uniform film thickness and linear partition equilibrium were in relatively good agreement with the experimental data for the combined continuous and preparative Chromatographie system, and it could be used as a powerful predictive tool for determining the optimum operating conditions.