• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.597-608
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• 1994

A new process for the production of high purity ${\alpha}-Al_2O_3$ from ammonium aluminium sulfate solution abtained through the sulfation of low grade bauxite ore with $(NH_4)_2SO_4$, and leaching of the sulfated product was investigated. This process is consisted of solvent extraction for Fe component removal from ammonium aluminum sulfate solution and homogeneous precipitation of Al containing precipitate from the refined ammonium aluminium sulfate solution by using urea as precipitator. The optimum conditions of solvent extraction with Alamine 336 as extractant were shaking time of 4min, organic phase ratio to aqueous phase of 0.25. The types of precipitation products from this precipitation were amorphous alumina gel, pseudo-boehmite and crystalline boehmite in the lower temperature of $100^{\circ}C$, in the range from $125^{\circ}C$ to $150^{\circ}C$, and above $150^{\circ}C$, respectively. And also amorphous alumina gel hydrate in $1000^{\circ}C$ and crystalline boehmite in $1250^{\circ}C$ were tranfered to ${\alpha}-Al_2O_3$, respectively. This alumina was identified as ${\alpha}-Al_2O_3$ of purity 99.7%.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.430-436
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• 2014

Allura Red (AR) is a water-soluble harmful tar-based food colorant (FD & C Red 40). Batch adsorption studies were performed for the removal of AR using bituminous coal based granular activated carbon as adsorbent by varying the operation parameters such as adsorbent dosage, initial concentration, contact time and temperature. Experimental equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The equilibrium process was described well by Freundlich isotherm. From determined separation factor ($R_L$), adsorption of AR by granular activated carbon could be employed as effective treatment method. Temkin parameter, B was determined to 1.62~3.288 J/mol indicating a physical adsorption process. By estimation of adsorption rate experimental data, the value of intraparticle diffusion rate constant ($k_m$) increased with the increasing adsorption temperature. The adsorption process were found to confirm to the pseudo second order model with good correlation. Thermodynamic parameters like change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The negative Gibbs free energy change (${\Delta}G$ = -2.16~-6.55 kJ/mol) and the positive enthalpy change (${\Delta}H$ = + 23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.656-662
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• 2013

The iron oxide ($Fe_3O_4$) particles in the coolant of the secondary system of a nuclear power plant reduce the heat transfer performance or induce corrosion on the surface of the heat transfer tube. To prevent these problems, we conducted a study to improve the dispersion stability of iron oxide using polymeric dispersant injection in simulated secondary system water. The three kinds of anionic polymers containing carboxyl groups were selected. The dispersion characteristics of the iron oxide particles with the polymeric dispersants were evaluated by performing a settling test and measuring the transmission, the zeta potential, and the hydrodynamic particle size of the colloid solutions. Polymeric dispersants had a significant impact on the iron oxide dispersion stability in an aqueous solution. While the dispersant injection tended to improve the dispersion stability, the dispersion stability of iron oxide did not increase linearly with an increase in the dispersant concentration. This non-linearity is due to the agglomerations between the iron oxide particles above a critical dispersant concentration. The effect of the dispersant on the dispersion stability improvement was significant when the dispersant concentration ratio (ppm, dispersant/magnetite) was in the range of 0.1 to 0.01. This suggests that the optimization of dispersant concentration is required to maximize the iron oxide removal effect with the dispersant injection considering the applied environments, the iron oxide concentration and the concentration ratio of dispersant to iron oxide.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.112-117
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• 2017

This study demonstrated the emission of combustion gases of medium density fibreboard (MDF)s coated with piperazinomethyl-bis-phosphonic acid (PIPEABP), methylpiperazinomethyl-bis-phosphonic acid (MPIPEABP), N,N-dimethylethylenediaminomethyl-bis-phosphonic acid (MDEDAP), or bis-(dimethylaminomethyl) phosphinic acid (DMDAP). Each MDFs were coated in three times with a brush with 15 wt% aqueous solution of the phosphorus-nitrogen acid additives. After the specimens were dried at room temperature, the emission of combustion gases was tested using a cone calorimeter (ISO 5660-1, 2). The peak smoke production rate ($SPR_{peak}$) of the specimens coated with phosphorus-nitrogen acids was 18.5 to 41.5%, which is lower than that of using the virgin plate. However, the production of peak carbon monoxide ($CO_{peak}$) was 6.7 to 24.2% higher than that of using the virgin plate. Also, the peak carbon dioxide ($CO_{2peak}$) was 4.2 to 24.4% lower than that of using virgin plate. While the peak oxygen depletion rate was much higher than the level of 15%, which can be fatal to humans and the resulting risk could thus be eliminated. Overall, the combustibility of coated specimens was partially suppressed, but showed a negative effect on the reduction of carbon monoxide.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.73-79
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• 2017

Maleic anhydride (MAH) grafted polypropylene (PP-g-MAH) copolymers were prepared by changing MAH and styrene monomer (SM) content, using a twin screw extruder at $190^{\circ}C$. The grafting degree was measured by non-aqueous back titration method. The grafting degree of PP-g-MAH-SM copolymer was higher than that of PP-g-MAH at the same MAH content. PP-g-MAH-SM/kenaf fiber (KF) composites were also prepared by using a PP-g-MAH as a matrix at $200^{\circ}C$ and the KF content was fixed at 20 wt%. Based on the degradation temperature investigated by TGA, the thermal stability of PP-g-MAH-SM/KF composites was more enhanced than that of PP-g-MAH only. Mechanical properties of the composites were also improved when MAH and SM applied together. The adhesion degree between the copolymer and KF was confirmed by both SEM pictures of the fractured surface and contact angles.

• Applied Biological Chemistry
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• v.41 no.5
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• pp.390-394
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• 1998

The tuber of Liriope platyphylla was extracted with 80% aqueous MeOH and solvent-fractionated with EtOAc, n-BuOH and $H_2O$. Evaluation of growth inhibitory activity of each fractions on various carcinoma cells, A549, SK-OV-3, SK-Mel-2, XF-498 and HCT-15, indicated the n-BuOH fraction to be the highest in the activity. From the fraction, two saponin compounds were isolated through Amberlite XAD-II and silica gel column chromatographies, repeatedly, and their chemical structures were elucidated as spicatoside A and B by interpretation of spectral data, NMR and IR, and adaptation of acid hydrolysis. Spicatoside A showed growth inhibitory activity on carcinoma cells, and the $IC_{50}$ values against A549, SK-OV-3, SK-Mel-2, XF-498 and HCT-15 cells were determined to be 17.3, 21.7, 14.9, 18.8 and $15.6\;{\mu}g/ml$, respectively.

• Applied Biological Chemistry
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• v.38 no.5
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• pp.478-483
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• 1995

To investigate the constituents of antimutagenic factor from brown rice, methanol extracts were fractionated into ether, ethylacetate, buthanol and aqueous fractions. The ether fractions showed distinct antimutagenic effect and active spot were selected by silica gel chromatography. The specific activity of active spot decreased with isolation of the active components from the methanol extract. Qualitative analyses of the active spot by using various spraying reagents revealed that ninhydrin and orcinol did not develop colored reactions. But, ferric chloride, 2,7-dichlorofluorescein, antimony pentachloride, phosphomolybdic acid, bromothymol blue and rhodamine 6G led to colored reactions. These results suggested that the consitituents of active material were neither polar nor nitrogen-containing compounds and that they may contain phenolic compounds and fatty acid derivatives. Main compounds of the active spot were analyzed to be o-hydroxy benzyl alcohol(saligenin), octanoic acid(caprylic acid), 9,12-cis-octadecadienoic acid(linoleic acid), 11-cis-octadecenoic acid(oleic acid), hexadecanoic acid(palmitic acid), 1H-indole-2-carboxylic acid and 1,2-benzenedicarboxylic acid(phthalate) in GC/Mass spectrum, and antimutagenicity of these active compounds using standard regeant was reconfirmed in S. typhimurium reversion assay.

• Journal of Applied Biological Chemistry
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• v.56 no.1
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• pp.23-27
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• 2013

The roots of Brassica rapa ssp. were extracted with 95% aqueous ethanol and the concentrated extracts were partitioned using ethyl acetate (EtOAc), n-butyl alcohol and $H_2O$, successively. From the EtOAc fraction, five flavonoids were isolated through repeated silica gel and octadecyl silica gel (ODS) column chromatography (c.c.). Based on NMR, mass spectrometry (MS) and IR spectroscopic data, the chemical structures of the compounds were determined to be licochalcone A (1), 4,4'-dihydroxy-3'-methoxychalcone (2), liquirtigenin (3), liquiritin (4), and isoliquiritin (5). This is the first report of these compounds isolated from the root of this plant.

• Journal of Applied Biological Chemistry
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• v.59 no.4
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• pp.357-360
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• 2016

Chrysanthemum morifolium flowers were extracted with 80 % aqueous MeOH, and the concentrated extract was partitioned into EtOAc, n-butyl alcohol (n-BuOH), and water fractions. The repeated silica gel and octadecyl silica gel column chromatographies for the EtOAc and n-BuOH fractions led to isolation of four flavonoids. The chemical structures of the compounds were determined as acacetin (1), apigenin (2), apigenin-7-O-${\beta}$-$\small{D}$-glucopyanoside (3), acacetin-7-O-${\beta}$-$\small{D}$-glucopyranoside (4) based on spectroscopic data analyses including nuclear magnetic resonance, mass spectrometry, and infrared spectrometry.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.541-546
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• 2000

Methods to determine L-dopa(L-3,4-dihydroxyphenylalanine) in aqueous solution by spectrofluorimetry based upon the ligand sensitized luminescence of Tb(III) ion L-dopa complex have been studied. Tb(III) ion and Lu(III) ion were used as ligand sensitized fluorescencer and co-fluorescence enhancer, respectively. The effects of excitation wavelength, pH, concentration of Tb(III) ion, concentration of Lu(III) ion and emission wavelength on the fluorescence intensity were investigated. The fluorescence intensity of the Tb(III) ion L-dopa complex was further increased with addition of Lu(III) ion. The calibration curve for L-dopa was linear over the range from 5.0 ${\times}$ $10^{-7}$ M to 1.0${\times}$ $10^{-4}$ M and the detection limit was 4.0 ${\times}$ $10^{-8}$ M under the optimal experimental conditions of 300 nm, 8.0, 1.0 ${\times}$ $10^{-4}$ M and 545 nm for excitation wavelength, pH, concentration of Tb(III) ion and emission wavelength, respectively. When Lu(III) ion was added to Tb(Ⅲ) ion L-dopa complex, the concentration range of linear response and detection limit were 1.0${\times}$$10^{-8}$ M to 2.0 ${\times}$ $10^{-4}$ M and 1.0 ${\times}$ $10^{-9}$ M, respectively under the optimal experimental conditions of 300 nm, 8.5, 1.0 ${\times}$ $10^{-5}$ M, 1.0 ${\times}$ $10^{-5}$ M, 545 nm for excitation wavelength, pH, concentration of Tb(III) ion, concentration of Lu(III) ion and emission wavelength, respectively.