Seung Nam Joung

Measurement and correlation of solubility of disperse anthraquinone and azo dyes in supercritical carbon dioxide

The solubility of three disperse anthraquinone dyes and two azo dyes in supercritical CO2 was measured. The tested dyes are Celliton fast blue B, l-amino-2-methylanthraquinone, 1-methylaminoanthraquinone, disperse Red 1 and 4-[4-(phynylazo)phenylazo]-o-cresol. Solubility measurements were made at 313.15-393.15 K and 10-25 MPa in a high-temperature autoclave phase equilibrium apparatus. Pure physical properties of the dyes such as critical constants, molar volumes and vapor pressures were estimated based on semi-empirical methods. Also, the data were quantitatively modeled by both an empirical density correlation and a quantitative equation of state recently proposed by the present authors based on nonrandom lattice theory. We found that anthraquinone disperse dyes in general show higher solubility than azo disperse dyes in supercritical CO2 within the experimental ranges.

Extraction of lanthanide ions from aqueous solution by modified supercritical CO2: tri-n-butylphosphate+CO2 and bis-2-ethylhexyl phosphoric acid+CO2

Abstract High-pressure single-phase limit of binary tri-n-butylphosphate (TBP)+CO2 and bis-2-ethylhexyl phosphoric acid (B2EHPA)+CO2 was measured. By a variable-volume view-cell apparatus, the phase transition pressures of each system were measured at various phase-equilibrium conditions (313.15–333.15 K, 10–25 MPa, 3.7–18.9 mol% TBP and 1.0–45.0 mol% B2EHPA). Based on this data, supercritical fluid extraction (SFE) was carried out for lanthanide ions from acidic aqueous solution. In the first place, SFE was carried out for Nd3+ over a wide range of conditions (0–5 M HNO3, 313.15–333.15 K and 10–25 MPa) and optimum SFE process conditions are evaluated. In the second place, SFE was carried out at 313.15 K and 25 MPa for six types of lanthanide ions (La3+, Ce3+, Nd3+, Sm3+, Eu3+, and Yb3+) from 1 M HNO3 acidic solution and the characteristics of different metals on the SFE were compared.

Measurements and Correlation of Hydrogen-Bonding Vapor Sorption Equilibrium Data of Binary Polymer Solutions

Vapor sorption equilibrium data of ten binary polymer/solvent systems were measured using sorption equilibrium cell equipped with a vacuum electromicrobalance. Tested solvents were water, methanol, ethanol and npropanol and polymer solutes were poly(ethylene glycol), poly(propylene glycol), poly(tetramethylene glycol) and poly(ethylene oxide). The measured sorption obtained in the present work, were compared with existing literature data and the degree of reliability of the measured data was discussed. Vapor sorption equilibrium data obtained in the present study were correlated by UNIQUAC model and the multi-fluid non-random lattice fluid hydrogen bonding equation of state (MF-NLF-HB EOS) recently proposed by the present authors.

Modifier effects on supercritical CO2 extraction efficiency of cephalotaxine fromCephalotaxus wilsoniana leaves

The effects of modifiers such as methanol, water, diethylamine in methanol (10 v/v %), and diethylamine in water (10 v/v %) were investigated at three different concentrations (1, 5, and 10 v/v %) of the modifiers in supercritical CO2 (SC-CO2) in order to enhance the supercritical fluid extraction (SFE) efficiency of cephalotaxine fromCephalotaxus wilsoniana leaves. Among the modifiers employed, methanol basified with diethylamine was found to greatly enhance the extraction efficiency relative to any other modifiers employed. The results suggest that cephalotaxine in plant matrices may be readily changed from SC-CO2-insoluble salt to SC-CO2-soluble free base by basified modifiers. In addition, SC-CO2 modified with basified methanol could enhance the extraction efficiency of cephalotaxine more than 30% when compared to the conventional organic solvent extraction.

Thermolysis of Scrap Tire Using Supercritical Toluene

With toluene in the supercritical state, scrap tire was decomposed into low molecular weight hydrocarbon liquid and solid residual. The experiment was carried out at 523.15, 573.15 and 623.15 K and pressures of 5, 10, and 15 MPa. The liquid and solid residual products were further separated by a simple filtering method. The reaction time, tire weight and the amount of the solvent were determined for the optimal thermolysis. The decomposition percent and TGA were used to evaluate the decomposition characteristics in terms of temperature and pressure. The GC-MS was applied to the decomposed liquid products from the various conditions. The average molecular weight of the decomposed liquid products tended to become lower with the increasing temperature.

Oxidation characteristics of phthalic and adipic acids by supercritical water

Supercritical water oxidation (SCWO) was carried out in a flow-type reactor for modeling of waste-water containing phthalic or adipic acid. For each acid, the reaction order and rate constant, k, were determined over a wide range of experimental conditions : temperatures from 633.15 to 713.15 K, pressures from 18 to 29 MPa, excess amounts of hydrogen peroxide from zero to 800 percent, and the mean residence time in the reactor from 1.1 to 49.1 seconds. The concentration of both acids in model wastewater was set by 500 ppm. For phthalic acid, we found that the orders of decomposition reaction with respect to the reactant concentrations were 0.56 for phthalic acid, 0.31 for hydrogen peroxide, and 0.53 for water. For adipic acid, the orders of oxidation were 0.78 for adipic acid, 0.53 for hydrogen peroxide, and 0.74 for water. Then measured activation energy for phthalic acid was 33.08 kcal/mol and that for adipic acid was 19.51 kcal/mol, respectively.