• Journal of the Korean Chemical Society
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• v.30 no.4
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• pp.359-368
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• 1986

Solvent extraction equilibria of alkali metal cation with crown ether (DC18C6, DC24C8) and HDEHP have been studied. The extraction equilibrium constants increase in the order of, in the DC18C6 system, $Na^+, and in the DC24C8 system, $Rb^+. The species extracted to organic phase are $M_1(crown ether)_1\;(HDEHP)_1$. The magnitude of extraction equilibrium constant is determined by the distribution ratio of crown ether between organic and aqueous phase, and stability constant of crown ether-alkali metal complex.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.380-387
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• 2018

Finding poly(amidoxime) (PAO) based adsorbent with better performance in U(VI) extraction from seawater is a hot research topic. By employing plasma treatment, the bi-functionalized adsorbents containing amidoxime and phosphate (labelled as $PO_4/PAO$) were successfully synthesized. The obtained $PO_4/PAO$ was characterized and applied for the potential extraction of U(VI) from aqueous solution. The results show that $-PO_4$ enhanced the hydrophilicity of PAO. $PO_4/PAO$ possesses good selective sorption ability for U(VI) and excellent reusability. The findings is helpful to understand optimizing performance of PAO based adsorbents for uranium extraction from seawater.

• Analytical Science and Technology
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• v.36 no.4
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• pp.152-160
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• 2023

Adenosine and cordycepin are bioactive compounds with health benefits. Therefore, both substances are often used to assess the quality of Cordyceps products. Optimization and validation of the HPLC/DAD method for determining two nucleosides were studied. The samples were prepared using an ultrasound-assisted extraction (ultrasonic bath). The result was optimal conditions for aqueous extraction, an extraction time of 35 min, and an extraction temperature of 40 ℃. The Chromatographic separation was achieved using a reverse phase column (InfinityLab Poroshell 120 EC-C18, 4.6 × 250 mm, 2.7 ㎛) at 30 ℃ with a mobile phase gradient elution of water and methanol at a flow rate of 0.7 mL/min. The eluents were monitored via a diode array detector at 260 nm. Two nucleosides were separated by less than 12 min after injection. The developed method was found to be excellent linear (r² > 0.9999), accurate (% recovery 95.34-98.51), and precise (% relative standard deviation < 2.0). The limit of detection (LOD) and quantification (LOQ) were 0.45 and 1.38 mg/mL for adenosine and 0.47 and 1.43 mg/mL for cordycepin, respectively. This method was satisfactory for simultaneously quantitating two nucleoside contents, which were used to evaluate Cordyceps products.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2926-2936
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• 2021

Rare-earth (RE) industries generate a massive amount of radioactive residue containing high thorium concentrations. Due to the fact that thorium is considered a non-economic element, large volume of these RE processed residues are commonly disposed of without treatment. It is essential to study an appropriate treatment that could reduce the volume of waste for final disposition. To this end, this research investigates the applicability of carbon-based adsorbent in separating thorium from aqueous phase sulphate is obtained from the cracking and leaching process of solid rare-earth by-product residue. Adsorption of thorium from the aqueous phase sulphate by carbon-based electrodes was investigated through electrosorption experiments conducted at a duration of 180 minutes with a positive potential variable range of +0.2V to +0.6V (vs. Ag/AgCl). Through this research, the specific capacity obtained was equivalent to 1.0 to 5.14 mg-Th/g-Carbon. Furthermore, electrosorption of thorium ions from aqueous phase sulphate is found to be most favorable at a higher positive potential of +0.6V (vs. Ag/AgCl). This study's findings elucidate the removal of thorium from the rare-earth residue by carbon-based electrodes and simultaneously its potential to reduce disposal waste of untreated residue.

• The Korean Journal of Ecology
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• v.12 no.1
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• pp.21-35
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• 1989

It was found that seed germination and seedling growth of selected species were inhibited by phytotoxic substance released from black pine. The longer was the aqueous extraction time of black pine needles, the smaller was the relative germination and growth of the species were inhibited in aqueous leachate and rain leachate as well as in soil underneath the black pine trees. In addition, the growth of lettuce was suppressed in volatile substances from black pine needles. To detect phytotoxic substances of black pine needles, paper chromatography and high performance liquid chromatography were used and fourteen kinds of KDICical compounds were isolated and identified as phenolic acids including benzoic acids. The growth of lettuce was inhibited in the experiment using reagents identical to these KDICical substances and a great inhibition was observed in the concentration of less than 5$\times$ M.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.183-186
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• 2002

Experiments in the batch soil/aqueous systems were conducted to compare the sorption onto soil and extraction efficiency of sorbed phenanthrene in the presence of the micelle-forming anionic surfactant(SDS) or the micelle-like amphiphilic nano-sized polyurethane particles. Micelle-like amphiphilic nano-sized polyurethane(APU) particles synthesized from amphiphilic urethane acrylate anionomers(UAA) could solubilize phenanthrene within their hydrophobic interiors as the same way that surfactants micelles did in aqueous phase.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3444-3450
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• 2013

Three phase hollow fiber-liquid phase microextraction (HF-LPME), which is faster, simpler and uses a more environmentally friendly sample-preparation technique, was developed for the analysis of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) in human urine. For the effective simultaneous extraction/concentration of NSAIDs by three phase HF-LPME, parameters (such as extraction organic solvent, pH of donor/acceptor phase, stirring speed, salting-out effect, sample temperature, and extraction time) which influence the extraction efficiency were optimized. NSAIDs were extracted and concentrated from 4 mL of aqueous solution at pH 3 (donor phase) into dihexyl ether immobilized in the wall pores of a porous hollow fiber, and then extracted into the acceptor phase at pH 13 located in the lumen of the hollow fiber. After the extraction, 5 ${\mu}L$ of the acceptor phase was directly injected into the HPLC/UV system. Simultaneous chromatographic separation of seven NSAIDs was achieved on an Eclipse XDB-C18 (4.6 mm i.d. ${\times}$ 150 mm length, 5 ${\mu}m$ particle size) column using isocratic elution with 0.1% formic acid and methanol (30:70) at a HPLC-UV/Vis system. Under optimized conditions (extraction solvent, dihexyl ether; $pH_{donor}$, 3; $pH_{acceptor}$, 13; stirring speed, 1500 rpm; NaCl salt, 10%; sample temperature, $60^{\circ}C$; and extraction time, 45 min), enrichment factors (EF) were between 59 and 260. The limit of detection (LOD) and limit of quantitation (LOQ) in the spiked urine matrix were in the concentration range of 5-15 ng/mL and 15-45 ng/mL, respectively. The relative recovery and precision obtained were between 58 and 136% and below 15.7% RSD, respectively. The calibration curve was linear within the range of 0.015-0.96 ng/mL with the square of the correlation coefficient being more than 0.997. The established method can be used to analyse of NSAIDs of low concentration (ng/mL) in urine.

• Analytical Science and Technology
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• v.17 no.4
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• pp.289-294
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• 2004

A high performance liquid chromatographic method was designed for the quantitative analysis of oxymatrine in Sophora Radix. The separation of oxymatrine was performed by reversed-phase chromatography with a $C_{18}$ column and a buffered aqueous solution containing acetonitrile, and monitored by UV absorption at 215 nm. Extraction of oxymatrine in Sophora Radix was carried out using various solvents and extraction methods. The optimum extraction efficiency for the crushed Sophora Radix was achieved by reflux at $80^{\circ}C$ in 50% ethanol for five hours. Most extraction methods used to complicate pretreatments. In this study, sublimation was employed for a extraction method without going through complicate pretreatments. Sublimation was carried out under high vacuum ($1{\times}10^{-3}$ torr) and at high temperature ($200^{\circ}C$). Extraction efficiency using Sublimation was found to be inferior to other extraction methods.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.78-85
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• 2006

In textile industries, waste effluent containing zinc is generated during the manufacture of rayon yarn from the wood pulp or cotton linters. Due to the strict environmental regulations and the presence of toxic metallic and other constituents, the discharge of industrial effluents in the sewage or disposal of solid sludge as landfill is restricted. Before recycling of zinc as zinc sulphate solution to the spinning-bath of the rayon manufacturing plant the zinc sulphate solution must be free from calcium, which is deleterious to the process as gypsum precipitates with the increase in concentration and forms scale in the bath. In the present work an attempt has been made to develop a process following solvent extraction technique using thiophosphinic extractants, Cyanex 272 and 302 modified with isodecanol and diluted in kerosene to recover zinc from rayon effluent. Various process parameters viz. extraction of zinc from different concentration of solution, distribution ratio, selective extraction, O/A ratio on extraction and stripping from the loaded organic, complex formation in the organic phase etc. have been studied to see the feasibility of the process. The extractant Cyanex 302 has been found selective for the recovery of 99.99% of zinc from the effluent above equilibrium pH 3.4 maintaining the O/A ratio of 1/30 leaving all the calcium in the raffinate. It selectively extracted zinc in the form of complex $[R_{2}Zn.3RH]_{org}$ and retained all the calcium in the aqueous raffinate. The zinc from the loaded Cyanex 302 can be stripped with 10% sulphuric acid at even O/A ratio of 10 without affecting the stripping efficiency. The stripped solution thus obtained could be recycled in the spinning bath of the rayon plant. The raffinate obtained after the recovery of zinc could be disposed safely without affacting environment.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.168-172
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• 2007

The separation of indole from a model mixture comprising four kinds of nitrogen heterocyclic compounds [indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine (Qu)], three kinds of bicyclic aromatic compounds [1-methylnaphthalene (1MN), 2-methylnaphthalene (2MN), dimethylnaphthalene (DMN)], biphenyl (Bp) and phenyl ether (Pe) was examined by batch cocurrent 4 stages equilibrium extraction. The model mixture used as a raw material in this work was prepared according to the components and compositions contained in coal tar fraction (the temperature ranges of fraction: $240{\sim}265^{\circ}C$). An aqueous solution of formamide was used as a solvent. Indole was recovered more than 99% through 4 stages of the equilibrium extraction. The range of selectivity of indole in reference to DMN obtained through the 5 stages equilibrium extraction was found to be 63~118. The process for separation and recovery of indole contained in coal tar was studied by using the experimental results obtained from this work and the previous work.