• Clean Technology
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• v.17 no.1
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• pp.19-24
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• 2011

The bubble point pressures of binary mixtures of carbon dioxide ($CO_2$) and N,N-dimethylformamide (DMF) were measured by using a high-pressure experimental apparatus equipped with a variable-volume view cell, at various $CO_2$ compositions in the range of temperatures above the critical temperature of $CO_2$ and below the critical temperature of DMF. The experimental bubble point pressure data were correlated with the Peng-Robinson equation of state (PR-EOS) to estimate the corresponding dew point compositions at equilibrium with the bubble point compositions. The experimentally measured bubble point pressures gave good agreement with those calculated by the PR-EOS. The variable-volume view cell equipment was verified to be an easy and quick way to measure the bubble point pressures of high-pressure compressible fluid mixtures.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.234-238
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• 2015

The separation of nitrogen heterocyclic compound (NHC) contained in a model coal tar fraction was compared by the methanol and formamide extraction. The model coal tar fraction comprising four kinds of NHC (NHCs : quinoline, iso-quinoline, indole, quinaldine) and three kinds of bicyclic aromatic compound (BACs : 1-methylnaphthalene, 2-methylnaphthalene, dimethylnaphthalene), biphenyl and phenyl ether was used as a raw material. The aqueous solution of methanol and formamide were used as solvents. A batch-stirred tank was used as the raw material - a solvent contact unit of this work. Independent of the solvent used, the distribution coefficient of NHCs sharply increased by decreasing the initial volume ratio of water to the solvent and increasing the equilibrium operation temperature, whereas, the selectivity of NHCs in reference to BACs decreased. Decreasing the initial volume ratio of solvent to feed resulted in deteriorating distribution coefficients, but the selectivity of NHCs in reference to BAC was almost the constant. The distribution coefficient of NHCs by the methanol extraction was 3~5 times higher than that of NHCs by the formamide extraction, inversely, the selectivity of NHCs based on BACs by the formamide extraction was 3~7 times higher than that of NHCs by the methanol extraction. Furthermore, two different solvent extraction methods by adding the extraction processing speed to the balance between solvency and selectivity of NHCs were compared.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.155-159
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• 2019

As a part of improving the quality for the fraction of the waste plastics pyrolysis oil (WPPO), the recovery of paraffin components contained in the fraction was investigated by dimethylformamide (DMF) equilibrium extraction. The fraction of a distilling temperature of $120{\sim}350^{\circ}C$ recovered from WPPO by the simple distillation and the aqueous solution of DMF were used as a raw material and solvent, respectively. The concentrations of paraffin components ($C_{12}$, $C_{14}$, $C_{16}$ and $C_{18}$) contained in the raffinate decreased by increasing the mass fraction of water in the solvent at an initial state ($y_{w,0}$), whereas, the concentrations of paraffin components contained in the raffinate increased by increasing the mass ratio of the solvent to the feed at an initial state $(S/F)_0$. The concentrations of $C_{12}$, $C_{14}$, $C_{16}$ and $C_{18}$ paraffin components present in the raffinate recovered at $(S/F)_0=10$ were about 1.37, 2.0, 2.46 and 3.16 times higher than those of the raw materials, respectively. Recovery rates (residue rates present in raffinate) of paraffin components rapidly increased with increasing $y_{w,0}$, and decreasing $(S/F)_0$. The raffinate recovered through this study was expected to be used as a renewable energy.

• Polymer(Korea)
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• v.24 no.6
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• pp.787-793
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• 2000

The acrylonitrile copolymer/dimethylformamide (DMF) solutions were prepared to investigate the gelation behavior and critical gel concentration (c＊). Gelation is rapidly progressed with the increase of molecular weight of copolymer, but significantly delayed with supercooling temperature and comonomer contents. The c＊ behavior showed contrary trend against gelation behavior. In dynamic viscoelastic test, two glass-transition region were observed in film obtained from gelled solution whereas one glass-transition in film obtained from true solution. This result supports the idea that an ordered junction zone is formed by the dipole-dipole interaction of intermolecularly neighboring stereo-regular parts of atactic acrylonitrile copolymer chains due to a nucleation process in the solution.

• Membrane Journal
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• v.9 no.2
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• pp.132-139
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• 1999

Solid scintillation proximity membranes were prepared for measuring the amount of radioactivity in laboratories contaminated by the radionuclide of $^3H$-cortisol. The membranes, consisting of polysulfone as a polymer matrix and cerium activated yttrium silicate as a fluor, were used to monitor the amount of radioactivity without the aid of a scintillation cocktail required for the conventional wipe test. The test results of the cocktail-free wipe test showed that the prepared membranes were efficient to monitor radionuclide-contaminated areas with the good counting ability as well as with the decrease of overall production of radioactive waste. On the other hand, solvent treatment of the prepared membranes could induce a significant variation of membrane morphology, but the counting efficiency of the solvent-treated membranes was not improved than that of the untreated one.

• Journal of the Korean Chemical Society
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• v.29 no.3
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• pp.226-232
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• 1985

Dioxomolybdenum(VI) complexes, MoO$_2$(H-Sal-R)$_2$, R; arylamines, have been synthesized by reactions of dioxobis (salicylaldehydato) molybdenum(VI) with various primary amines. These complexes have been characterized by electric conductivity and spectroscopic studies. Infrared, uv-vis, and proton nmr spectra show that the complexes are six-coordinated with cis-MoO$_2$ group. And mass spectra indicates that the combining ratios for Mo (VI)-ligand are 1 : 2. They are yellow, stable for a considerably long time in the atmosphere at room temperature and slightly soluble in alcohol, dichloromethane and dimethylformamide but insoluble in benzene, ether and carbon tetrachloride.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.965-970
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• 2008

The separation of sulfone components using light cycle oil(LCO) after oxidation was carried out by solvent extraction method using various polar solvents such as water, n-methyl-2-pyrrolidone(NMP), dimethyl sulfoxide, ethyl acetate, acetonitrile, dimethyl formamide, and methyl alcohol. It was found that phase separation between LCO layer and solvent occurred under mixed solvent adding a proper amount of water. The mixture solvent of NMP and water was a promising extraction solvent due to the selective removal and high distribution coefficient of sulfone component in LCO. 99.5% over of sulfur contents in LCO can be removed by 4 stages equilibrium extraction.

• Journal of Adhesion and Interface
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• v.4 no.4
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• pp.22-27
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• 2003

Chemical modification of carbon nanotube (CNT) was carried out using $HNO_3$ and $H_2SO_4$ and characterized by analyzing the CNT before and after the modification using FT-IR and titration. Aggregation behaviors were investigated using a real-time video microscope after the chemically modified CNT(mCNT) had been dispersed in organic solvents such as toluene, dimethylformamide (DMF) and N-methylpyrrolidone (NMP) by ultrasonication. The mCNT showed better dispersion in polar sovents of DMF and NMP than the rCNT. CNT/ poly(methylmethacrylate) (PMMA) films were prepared from solution DMF/PMMA solutions. The films containing mCNT also revealed the improved dispersion.

• Fire Science and Engineering
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• v.33 no.4
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• pp.9-15
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• 2019

The flash points of DMF based organic solvent mixtures used in the synthetic leather manufacturing process were measured. The test group was composed of seven types of solvent mixtures, which included DMF, toluene, and MEK. Each flash point was tested according to the international standard test methods of KS M 2010. The flash points were then predicted using some prediction models and compared with the measured data. From the analysis results, the binary mixtures with a mole ratio of less than approximately 0.7 showed that the measured values were under 25 ℃. This showed that the expectation for the flammable risk lowering effects due to the mixing of high flash point materials was reduced. In addition, the predicted values were evaluated using the average absolute deviation (A.A.D). The results showed that the Le Chatelier's models had an "A.A.D" of 1.95 ℃ and were the closest to the measured values.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.93-100
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• 2004

The smear media possible to sampling and radiation detection was prepared and evaluated for the surface contamination using indirect method. The films were made by impregnating Cerium Activated Yttrium Silicate (CAYS) in a polysulfone membrane. The membranes used solution as a dimethylformamide (DMF) and methylene chloride (MC), polysulfone as a polymer matrix and CAYS as a inorganic scintillator. The proximity membranes were prepared with single- and double-layered structure. The solidified methods were immersion to the nonsolvent bath such at water and ethanol and solvent evaporation. The measurement of the photon produced by interaction with radiation and inorganic scintillator used a photomultiflier tube (PMT), amplifier, and counter. In the comparison with the low background alpha/beta counter, the counter rate using inorganic scintillator proximity membrane for the $\^$14/C surface contamination was about 50%. Also. the $^3$H counting results revealed that the prepared membranes were efficient to monitor the surface contaminated with the low energy be-ray emitter nuclides.