• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.6
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• pp.303-308
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• 2017

The $FeCl_3$ waste solution used to etch various metals contains valuable metal such as nickel. In this study, we recovered as high purity nickel carbonate crystalline powders from nickel-containing etching waste solution after regeneration of iron chloride. Firstly we eliminated about of the iron impurities under the condition of pH 4 using 5 % NaOH aqueous solution and then removed the remaining impurities such as Ca, Mn and Zn etc. by using solvent extractant D2EHPA (Di-(2-ethylhexyl) phosphoric acid). Thereafter, nickel carbonate powder having a purity of 99.9 % or more was obtained through reaction with sodium carbonate in a nickel chloride solution.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.266-272
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• 1992

Azacrownoalkyl phenylphosphinic acids were synthesized and their competitive solvent extraction characteristics from water to chloroform layer were investigated. Phosphinic acids were synthesized in good yields by one step reaction of phenylphosphinate, aldehyde, and monoazacrown ether and then basic hydrolysis of the resulting phosphinate dsters. These complexing agents revealed a wide effective pH range in extraction of alkali metal ions from water to the organic phase and total metal ion loading at pH 11 was about 75%. The selectivity of the cation extraction was determined mainly by the cavity size of the azacrown ethers, showing $Na^+$ >> $K^+$ > $Rb^+$ > $Li^+$ > $Cs^+$ for the alkyl phenylphosphinic acid ${\underline{2}}$, containing monoaza-15-crown-5 and $K^+$ >> $Rb^+$ > $Na^+$ > $Cs^+$ > $Li^+$ for the alkyl phenylphosphinic acid, ${\underline{3}}$, containing monoaza-18-crown-6 moiety. Applicable pH range of these azacrown ether phosphinic acids in solvent extraction of alkali metal cations was wider than a crownether carboxylic acid with similar selectivity, showing considerable amount of metal ion loading in slightly acidic or neutral media.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.9
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• pp.671-682
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• 1998

Chemical structure and electrical characteristics of 5 commercial crosslinked polyethylenes (XLPE) used as insulating materials for medium voltage distribution power cables in Korea were investigated. It was found that each XLPE shows different properties depending on the type of XLPE. Chemical structural irregularities of pellets change considerably by crossliking reaction, with some irregularities being disappeared after crosslikeng reaction. It was also found through a solvent extraction study that additives such as crosslinking agent and antioxidants act as major source retarding water tree growth. Low molecular weight polyethylene chains plays a different role in water tree growth of XLPE.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.540-545
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• 1992

Kinetics and mechanism on the solvent extraction of nickel(Ⅱ) with 8-hydroxyquinoline (HOx) was studied spectrophotometrically. Absorbance variation was measured by changing the 8-hydroxyquinoline concentration in the chloroform organic phase and the pH values in the aquous phase. By analyzing absorbance data the reaction rate was found to be the first order for 8-hydroxyquinoline concentration and the inverse first one for [H$^+$]. Therefore the rate determining step of the extraction reaction is the formation of the one-to-one metal chelate NiOx$^+$ and the rate equation is as follows; -d[Ni$^{2+}$]/dt = k[Ni$^{2+}$][Ox$^-$] = k'[Ni$^{2+}$][HOx]$_0$/[H$^+$]. The value of k' was evaluated from the slope of plot of log [Ni$^{2+}$]$_0$/[Ni$^{2+}$]$_t$ versus time and the rate constant k was calculated according to the equation k' = k ${\times}$ K$_{HOx}$ / K$_{D,HOx}$. From the temperature dependence of the extraction rate, the activation energy E$_a$ = 6.26 kcal/mol is calculated, and activation parameters, ${\Delta}$G$^{\neq}_{298}$ = 6.59 kcal/mol, ${\Delta}$H$^{\neq}_{298}$ = 5.68 kcal/mol, ${\Delta}$S$^{\neq}_{298}$ = -3.09 eu/mol are estimated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.293-299
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• 2020

This study was undertaken to optimize combining the processes of enzymatic hydrolysis and extraction for lycopene production from autumn olive berry. The autumn olive berry was pulverized and suspended in water, followed by treatment with various hydrolytic enzymes including Ceremix, Celluclast, AMG, Viscozyme, Pectinex, Promozyme, Ultraflo and Tunicase. Reaction solutions were subjected to extraction by applying different organic solvents including acetone, ethyl acetate, hexane and chloroform. Highest yields of lycopene extraction were obtained with the Ceremix (hydrolysis enzyme) and chloroform (extraction solvent) combination. Subsequently, using this ideal combination, enzymatic hydrolysis conditions, including enzyme concentration, pH and temperature, were statistically optimized to 0.58%, 5.5 and 54.4℃, respectively, by applying the response surface method. The lycopene extraction yield increased 2.3-fold (22.6 mg/100g) by using the selected combined process. We propose that these results could be used for the future development of bioactive materials required for bio-health care products.

• Applied Chemistry for Engineering
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• v.35 no.3
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• pp.222-229
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• 2024

The use of low-toxic, hypoallergenic, and environmentally friendly natural pigments has increased. With growing interest in health, research on natural extracts containing beneficial substances for the human body is actively underway. In this study, natural pigments were extracted from sprout barley using a solvent extraction method and CCD-RSM was used to optimize the extraction process. The experiment's independent variables included extraction temperature, alcohol/ultra-pure volume ratio, and extraction time. The response variables were set to achieve a target chromaticity (L = 45, a = -35, b = 45), and to maximize DPPH radical scavenging activity evaluating the antioxidant capacity. The statistical significance of the main effect, interaction effect, and effect on the response value was evaluated and analyzed through the F and P values for the regression equation variables calculated using RSM optimization. Additionally, the reliability of the experiment was also confirmed through the P values of the probability plot graph. The extraction conditions for optimizing the four reaction values are 76.1 vol.% alcohol/ultra pure water volume ratio, an extraction temperature of 52.9 ℃ , and an extraction time of 49.6 min. Under these conditions, the theoretical values of the reaction values are L = 45.4, a = -36.8, and b = 45.0 DPPH radical scavenging activity = 30.9%. When the actual experiment was conducted under these optimal extraction conditions and analyzed, the measured values were L = 46.2, a = -36.1, and b = 48.2, and antioxidant capacity = 31.1% with an average error rate of 2.9%.

• Mass Spectrometry Letters
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• v.11 no.4
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• pp.71-76
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• 2020

While montelukast (ML), a cysteinyl-leukotriene type 1 receptor (CysLT1) antagonist is widely used to treat symptoms of rhinitis or asthma, its formulations are mainly limited to solid preparation due to its instability. Recently, there have been attempts to develop various ML dosage forms, and this situation increases the demand of sensitive and creditable methods to determine ML in various samples such as plasma. Thus, here, a simple and efficient method to determine ML in rat plasma using liquid-liquid extraction (LLE) and multiple reaction monitoring was presented. The mixture of DCM:EtOAc (25:75, v/v), the optimized extract solvent for LLE was found to be effective to extract ML without hydrophilic salts and proteins from the sample with limited volume. Also, the use of zafirlukast, instead of expensive ML-d6, as the internal standard makes the present method economical. The developed method was successfully validated in terms of selectivity, matrix effects (-14.8--6.9%), linearity (r230.998 within 0.5-500 ng/mL), sensitivity (the limit of detection and the lower limit of quantitation, ≤0.5 ng/mL), accuracy (88.4-100.6%), precision (3.0-13.3%), and recovery (80.8-86.3%) by following the FDA guidelines. Finally, the applicability of the validated method to pharmacokinetics (PK) studies was confirmed by the successful determination of PK parameters through it following oral administration of Singulair® granule in rats. Therefore, the present method can contribute to the development of new ML formulations through its performance to determine ML in rat plasma efficiently and sensitively.

• Mass Spectrometry Letters
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• v.13 no.4
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• pp.146-151
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• 2022

Rotigotine (RTG) is a non-ergot dopamine agonist used to manage the early stage of Parkinson's disease (PD) as transdermal patch. However, the poor medication compliance of PD patients and skin issues related with repeated applications of RTG patches lead to the search for alternative formulations and it also requires appropriate analytical methods for their in vivo evaluation. Thus, here, a sensitive, efficient, and cost-effective method to determine RTG in rat plasma using liquid-liquid extraction (LLE) and multiple reaction monitoring was developed. The use of 20 µL of rat plasma for sample treatment, 8-OH-DPAT as the internal standard, and methyl tert-butyl ether as the LLE solvent in the present method gives it advantages over previous methods for the analysis of RTG in biological samples. The good analytical performance of the developed method was confirmed in specificity, linearity (the coefficient of determination ≥0.999 within 0.1-100 ng/mL), sensitivity (the lower limit of quantitation at 0.1 ng/mL), accuracy (81.00-115.05%), precision (≤10.75%), and recovery (81.00-104.48%) by following the FDA guidelines. Finally, the applicability test of the validated method to the in vivo evaluation of a RTG formulation showed that the present method is the only method which can be accurately applied to that longer than 24 hours, critical for the development of formulations with reduced dosing frequencies. Therefore, the present method could contribute to the development of new RTG formulations helpful to people suffering from PD.

• Resources Recycling
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• v.25 no.2
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• pp.3-9
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• 2016

Separation of Zr(IV) and Hf(IV) from sulfuric acid solutions was investigated by extraction with several acidic extractants such as Versatic acid, LIX 63, and Cyanex 301. From strong sulfuric acid solutions, the separation of Zr(IV) and Hf(IV) by Versatic acid and LIX 63 was not possible, while selective extraction of Hf(IV) over Zr(IV) was obtained with Cyanex 301. However, the extraction percentage of the two metals was much lower compared to that by D2EHPA. Mixing of TBP with Cyanex 301 and D2EHPA led to negative effect on the extraction and separation of the two metal ions. The difference in the extraction reaction and separation selectivity between HCl, $HNO_3$ and $H_2SO_4$ media with each extractant was discussed.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.989-996
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• 2007

In this study, abiotic transformation of 1-naphthol(1-NP) via oxidative-coupling reaction and its reaction products were investigated in the presence of Mn oxides. The reaction products were characterized for their relative polarity using solvent extraction experiment and reverse-phase HPLC, and for structure using CCMS and LC/MS, and for absorption characteristics using UV-Vis spectrometry. The reaction products present in aqueous phase were more polar than parent naphthol and comprised of 1,4-naphthoquinon(1,4-NPQ) and oligomers such as dimers and trimers. Hydrophilic component present in water phase after solvent$(CH_2Cl_2)$ extractions was identified as naphthol polymerized products having molecular weight(m/z) ranging from 400 to 2,000, and showed similar UV-Vis. absorption characteristics to that of foil fulvic acid. Transformation of 1,4-NPQ, which is non-reactive to Mn oxide, to the polymerized products via cross-coupling reaction in the presence of 1-NP was also verified. In this experimental conditions(20.5 mg/L, 1-NP, 2.5 g/L $MnO_2$, pH 5), the transformation of 1-NP into the oligomers and polymerized products were about 83% of initial 1-NP concentrations, and more than 30% of the reaction products was estimated to be water insoluble fractions, not extracted by $H_2O$ methanol. Results from this study suggest that Mn oxide-mediated treatment of naphthol contaminated soils can achieve risk reduction through the formation of oligomers md polymer precipitation.