• 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.

• Membrane Journal
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• v.24 no.4
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• pp.317-324
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• 2014

It is very well known that the conventional polyamide (PA) thin film composite (TFC) reverse osmosis (RO) membranes have excellent permselective properties, but their chlorine tolerance is not good enough. In this study, to improve such chlorine tolerance, microporous membranes containing hydrophilic functional groups such as -COOH were used as a support to prepare PA TFC RO membranes, employing the conventional interfacial polymerization method. Meta-phenylene diamine (MPD) and 2,6-diamine toluene (2,6-DAT) were used as diamine monomers and tri-mesoyl chloride (TMC) as an acid monomer. The membranes prepared were characterized using various instrumental analytical methods and permeation test set-up. The flux obtained from the membranes prepared so was more than $1.0m^3/m^2day$ at 800 psi of operating pressure, while the salt rejection was over 99.0%. The chlorine tolerance of them was also found to be better than that of the membrane prepared by using conventional polysulfone support without hydrophilic functional groups.

• Membrane Journal
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• v.30 no.5
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• pp.283-292
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• 2020

Various kind of solutions need to be separated, purified, and concentrated using membranes in the field of industries. However, when the solution contains strong acids, the use of membrane is limited. Acid resistant membrane currently available in market does not show high efficiency of flux. This review explains the causes and mechanisms of changes in surface properties and performance of polyamide membranes when exposed to acidic solutions, and this can be used in the development of a membrane with acid resistance and high flux.

• 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.

• Journal of Food Hygiene and Safety
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• v.20 no.4
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• pp.191-198
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• 2005

The purpose of this study was to determine the level of acrylamide in various processed foods, some of which were chosen because they were known to contain an excessive amount of acrylamide. A total of 190 food products based on steamed rice, cereals, and potato chips were purchased from retail markets and analyzed with the LC-MS/MS method. Acrylamide was found to be widely distributed in all of the foods. The fried Potato chips contained the highest levels of acrylamide, at $470-3,572{\mu}g/kg$; these were lowered to $38-633{\mu}g/kg$ by vacuum frying. The median concentration of acrylamide was higher in snacks containing potato ($448{\mu}g/kg$) than in those with no potato ($133{\mu}g/kg$). The concentrations of acrylamide were 2-96 $\mu$g/kg in Korean staple foods, $48-61{\mu}g/kg$ in bone-extract soups, and $0-57{\mu}g/kg$ in Bulgogi sauce. These results suggest that the components of processed ffods and the processing methods are important determinants of acrylamide formation.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.748-751
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• 2003

Acrylamide is considered as potential carcinogen and genotoxicant. Swedish National Food Administration reported that acrylamide was detected in heat treated starch rich food products. Acrylamide formation during food processing was confirmed by researchers of other countries including UK, Norway, Japan, Switzerland, and United States. It is noticed that the formation of acrylamide in potato products was greater than other food products. It may be due to high concentration of asparagine and glucose in potato products comparing to those of other food products. Interaction between asparagine and glucose during heat treatment resulted in acrylamide formation via Maillard reaction. Analytical method (LC-MS/MS) adopted by FDA was performed to monitor acrylamide concentrations in domestic food products. Acrylamide quantitation in several food categories, such as raw materials, boiled foods, fried foods, hardtacks, breads, breakfast cereals, potato chips, french fries, biscuits, and others, were carried out.

• Korean Journal of Food Science and Technology
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• v.53 no.3
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• pp.245-251
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• 2021

We determined the quality characteristics, acrylamide concentration, and antioxidant activity of Nurungji prepared using white rice, brown rice, gamma-aminobutyric acid (GABA) brown rice, oats, and barley. The moisture content of Nurungji prepared using white rice was the lowest (1.48%) and the highest (6.53%) was obtained in barley Nurungji. The brightness (L^*) of white rice Nurungji was the highest, whereas that of GABA brown rice Nurungji was the lowest. The acrylamide concentration was the lowest (37.24 ㎍/g) in white rice Nurungji and the highest (255.50 ㎍/g) in oats Nurungji. The levels of total polyphenol and total flavonoid were the lowest in white rice Nurungji and high in oats and GABA brown rice Nurungji. The antioxidant activity was higher in Nurungji prepared using oats, GABA brown rice, brown rice, and barley than that using white rice. It is necessary to select an appropriate grain when preparing Nurungji by considering the amount of acrylamide produced.

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.178-185
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• 1999

For the process control of silicon nitride gelcasting, the composition effect of acryamide system on the viscosity of slip and mechanical property of gelcast green body were investigated. The slip was prepared by ball milling of silicon nitride suspension prepared with acrylamide monomer and polyelectrolyte dispersant after premixing them by attritor. The slip mixed with initiator was vacuum deaired and cast into molds, and then polymerized. The consolidated green body was obtained by drying the gelated slip. The viscosity measument and the diametral compression test was done to evaluate the rheological behaviro of slip and mechanical property of gelcast body, respectively. Experimental results showed that the high solid loading of silicon nitride slip was obtained up to 46 vol% with a low viscosity. The mechanical property of gelcast body mainly increased with increasing the concentration of monomer. The gelcast body was machinable above the ∼3 MPa of tensile strength. The relative density of pressured-sintered body was 98.5% at 1760$^{\circ}C$, 3 h.

• Journal of the Korean Wood Science and Technology
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• v.27 no.3
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• pp.63-72
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• 1999

For the purpose of improving the wet strength properties of paper, cellulosic fibers were modified by the processes of carbarmoylethylation and N-chlorocarbamoylethylation. Carbamoylethylated cellulose was prepared by the reaction of acrylamide with cellulosic fibers under the alkali catalyst, and N-chlorocarbamoylethylated cellulose was prepared by the addition of sodium hypochlorite into the carbamoylethylated cellulose. In carbamoylethylation reaction, the conditions of NaOH concentration, temperature and acrylamide addition rate were considered to be important factors. An initial reactivity and degree of substitution(DS) in carbamoylethylation of cellulosic fibers were effective according to increasing the addition rates of alkali, acrylamide and the temperature condition of $40^{\circ}C$. The effective wet strength properties by N-chlorocarbamoylethylation of cellulosic fibers were indicated under the conditions of DS 0.06. The wet strength of sheet was improved to 85% at the 100% basis of dry strength. From the photograph of scanning electron microscopy, fiber cuttings on the edge of sheet sample used in tensile strength testing were found in the N-chlorocarbamoylethylated sheet, due to the improvement of fiber bonding strength. The hypochlorite treatment was effective in the recycling of N-chlorocarbamoylethylated sheet, and was reduced the wet strength of sheet to be able to reslush.

• Proceedings of the Korean Fiber Society Conference
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• 1990.06b
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• pp.18-18
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• 1990