• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.434-440
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• 2003

The powders of L $a_{0.8}$C $a_{0.2}$Mn $O_3$ Colossal Magnetoresistance (CMR) materials were synthesized by sol-gel process. Lanthanum(H), Calcium(II) and Manganese(III) 2,4-Pentanedionate were dissolved in a mixed binary solution consisted of propionic acid and methanol with PEG (15 wt%) aqueous solution. The progress of reactions was monitored by FT-IR spectroscopy. The Lao scao.2Mn03 gel powders were annealed at various temperatures. The structural changes were investigated by FT-IR, CP/MAS $^{ 13}$C solid state NMR spectroscopy and XRD. The thermochemical property, particle characterization, microstructure of sintered sample, and cation composition of gel powder were studied by TG/DTA, FE-SEM and ICP-AES. The magnetic characterizations were identified through measurement of magnetic moment by VSM.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.632-637
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• 2010

Liquid-liquid equilibrium data for the quaternary system water +tetrahydrofuran + butyl acetate + isoamyl alcohol mixture were measured at 298.15 K and atmospheric pressure. Binodal curves, tie-lines, distribution, and selectivity for the quaternary system have been determined in order to investigate the effect of using binary solvents, butyl acetate and isoamyl alcohol, on extracting tetrahydrofuran from aqueous solution. In addition, these experimental tie-line data were also compared with the values predicted by the UNIFAC model. For the quaternary system, an average root-mean-square deviation for the system in 75/25, 50/50, and 25/75 mass ratios as mixed solvents are(3.35, 5.21 and 5.65) %, respectively.

• Polymer(Korea)
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• v.27 no.4
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• pp.370-376
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• 2003

Poly(DL-lactide-co-glycolide) nanoparticles were prepared by the modified spontaneous emulsification solvent diffusion method. Polymer solution was prepared by two water-soluble organic solvents, such as ethanol and acetone. Because of its biocompatible nature, PEG-PPG diblock copolymer was used as surfactant and stabilizer. The influence of several preparative variables on the nanoparticle formation, such as type and concentration of stabilizing agent, stirring methods, water/oil phase ratio and polymer concentration were investigated in order to control and optimize the process. After preparation of nanoparticles, particle size and distribution were evaluated by the light scattering particle analyzer. As results, the particle size was 50-200 nm and dispersibility was monodisperse. It was found that the appropriate selections of binary solvent mixtures and polymeric concentrations in both organic and aqueous phases could provide a good yield and favorable physical properties of PLGA nanoparticles.

• Membrane Journal
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• v.17 no.1
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• pp.61-66
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• 2007

A zeolite membrane shows better thermal, mechanical and chemical stabilities than a polymer membrane. Water was separated from iso-propyl alcohol (IPA)/water mixtures by pervaporation using the NaY zeolite membrane synthesized in the laboratory. The effects of a mole fraction of IPA in the feed solution and an operating temperature were studied on the permeation flux behavior and the separation factor of water with respect to IPA. As a mole fraction of IPA increased, the water flux as well as the separation factor decreased. As the experimental temperature increased, the water permeation flux increased while the separation factor decreased. For IPA/water binary mixtures, the water flukes through the NaY zeolite membrane were observed to be $1.9{\times}10^2{\sim}3.5{\times}10^3\;g/m^2{\cdot}hr$ and the separation factors were found to be $7.0{\times}10^2{\sim}2.0{\times}10^4$.

• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.479-486
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• 2003

In this study, poly(DL-lactide-co-glycolide) nanoparticles loaded with water-insoluble vitamins such as vitamin A (Retinol) and vitamin E acetate were prepared by the emulsification diffusion method. Polymer solution was prepared by the two water-miscible organic solvent, such as ethanol and acetone. Because of its biocompatible property, polyethyleneglycol-polypropyleneglycol diblock copolymer was used as surfactant and stabilizer. The influence of some preparative variables on the nanoparticle formation and on the loading efficiency of active agents, such as the type and concentration of stabilizing agent, the stirring methods, the water/oil phase ratio and the polymer concentration were investigated in order to control and optimize the process. After preparation of nanoparticles loaded with active agent, particle size and distribution were evaluated by the light scattering particle analyzer. The loading efficiency of active agents was evaluated by the UV-visible spectroscopy. As the results, particle size were 50-200 nm and dispersibility was monodisperse. The optimum loading efficiency of active agents was observed 50-60%. It was found that the appropriate of selections of binary solvent mixtures and polymeric concentrations in both organic and aqueous phases could provide good yield and favorable physical properties of PLGA nanoparticles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.136-152
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• 2017

The thermodynamic models, PC-SAFT (Perturbed-Chain Statistical Associated Fluid Theory) state equation and the Two-model approach liquid activity coefficient model NRTL (Non Random Two Liquid) + Henry + Peng-Robinson, for modeling the Rectisol process using methanol aqueous solution as the $CO_2$ removal solvent were compared. In addition, to determine the new binary interaction parameters of the PC-SAFT state equations and the Henry's constant of the two-model approach, absorption equilibrium experiments between carbon dioxide and methanol at 273.25K and 262.35K were carried out and regression analysis was performed. The accuracy of the newly determined parameters was verified through the regression results of the experimental data. These model equations and validated parameters were used to model the carbon dioxide removal process. In the case of using the two-model approach, the methanol solvent flow rate required to remove 99.00% of $CO_2$ was estimated to be approximately 43.72% higher, the cooling water consumption in the distillation tower was 39.22% higher, and the steam consumption was 43.09% higher than that using PC-SAFT EOS. In conclusion, the Rectisol process operating under high pressure was designed to be larger than that using the PC-SAFT state equation when modeled using the liquid activity coefficient model equation with Henry's relation. For this reason, if the quantity of low-solubility gas components dissolved in a liquid at a constant temperature is proportional to the partial pressure of the gas phase, the carbon dioxide with high solubility in methanol does not predict the absorption characteristics between methanol and carbon dioxide.