• Resources Recycling
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• v.31 no.4
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• pp.40-48
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• 2022

In waste lithium iron phosphate (LFP) batteries, the cathode material contains approximately 4% lithium. Recycling the constituent elements of batteries is important for resource circulation and for mitigating the environmental pollution. Li contained in the waste LFP cathode powder was selectively leached using persulfate-based oxidizing agents, such as sodium persulfate, potassium persulfate, and ammonium persulfate. Leaching efficiency and waste LFP powder properties were compared and analyzed. Pulp density was used as a variable during leaching, which was performed for 3 h under each condition. The leaching efficiency was calculated using the inductively coupled plasma (ICP) analysis of the leachate. All types of persulfate-based oxidizing agents used in this study showed a Li leaching efficiency over 92%. In particular, when leaching was performed using (NH₄)₂S₂O₈, the highest Li leaching percentage of 93.3% was observed, under the conditions of 50 g/L pulp density and an oxidizing agent concentration of 1.1 molar ratio.

• Journal of the Korean Chemical Society
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• v.27 no.4
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• pp.262-267
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• 1983

A study has been carried out for a scheme of the selective extraction and determination of cesium, sodium and nuclides by the ion association with dicyclohexyl-24-crown-8 and sodium tetraphenylborate from primary coolant of a pressurized water reactor. For that purpose, the effects of hydrogen, cesium and borate ions on the extraction have been investigated. Interferences of iodine and xenon nuclides were found but could be removed by reducing with sodium thiosulfate and back extraction with 1 N hydrochloric acid solution, respectively.

• Analytical Science and Technology
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• v.7 no.2
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• pp.245-251
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• 1994

In order to determine sodium chondroitin sulfate in the mixture, chondroitinase ABC was used for enzymatic reaction. The procedure was rapid, simple, quantitative and the HPLC analysis of ${\Delta}Di-6S$(2-actamido-2-deoxy-3-0-(${\beta}$-D-gluco-4-enepyranosyluronic acid)-6-0-sulfo-D-galactose) in the sodium chondroitin sulfate was obtained. The absorbance was measured at 230nm and detection limit was $1{\mu}g/ml$. When we applied this method to the drugs(capsule, opthalmic solution), it gave the mean contents of $100.01{\pm}1.58%$ and $99.89{\pm}1.80%$ respectively.

• Resources Recycling
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• v.31 no.5
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• pp.3-19
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• 2022

Electro-membrane technology is a process for separating and purifying substances in aqueous solution by electric energy using an ion exchange membrane with selective permeability, such as electrodialysis (ED) and bipolar electrodialysis (BMED). Electro-membrane technology is attracting attention as an environmental friendly technology because it does not generate by-products during the process and the recovered base or acid can be reused during the process. In this paper, we investigate the principles of ED and BMED technologies and various characteristics and problems according to the cell configuration. In particular, by investigating and analyzing research cases related to the treatment of waste sodium sulfate (Na₂SO₄), which is generated in large amounts during the metal recovery process.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.104-111
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• 2015

This study shows the mechanical properties of alkali-activated slag cement (AASC) synthesized using sulfate with NaOH solution. The used sulfates were calcium sulfate ($CaSO_4$, denoted CS) and sodium sulfate ($Na_2SO_4$, denoted SS). The replacement ratio of sulfates was 2.5, 5.0, 7.5 and 10.0% by weight of slag. NaOH solution of 2M and 4M concentration was used. A sample was activated with sulfate and activated with blended activator (blending NaOH solution with sulfate) respectively. 24 mix ratios were used and the water-binder weight ratio for the test was set 0.5. This research carried out the compressive strength, flexural strength, ultrasonic pulse velocity (UPV), absorption and X-ray diffraction (XRD). In the case of samples with CS, sample with 7.5% CS, sample with 2M NaOH+5.0% CS and sample with 4M NaOH+5.0% CS showed the good performance in the strength development. In the case of samples with SS, sample with 10.0% SS, sample with 2M NaOH+7.5% SS and sample with 4M NaOH+2.5% SS obtained good performance in strength. The results of UPV and water absorption showed a similar tendency to the strength properties. The XRD analysis of samples indicated that the hydration products formed in samples were ettringite, CSH and silicate phases. In this study, it is indicated that when compared to the use of sulfate only, the use of both sulfate and NaOH solution makes mechanical properties of AASC better.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.89-89
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• 2011

Cellulose섬유의 염색시 섬유가 물속에 침지되면 섬유표면은 음전하가 형성되어, 용액 속에서 음이온으로 존재하는 염료와의 반발력으로 인해 염료가 섬유에 접근하기가 어려워지며 따라서 염색이 원활하게 이루어지지 않는다. 그러나 염욕에 염화나트륨(sodium chloride, NaCl)이나 망초 즉, 황산나트륨(Glauber's salt, sodium sulfate, Na2SO4)과 같은 전해질을 첨가하면, 양이온인 sodium 이온이 섬유표면과 음이온 염료사이의 반발력을 감소시킨다. 따라서 음이온의 염료는 섬유표면에 접근할 수 있고, 고유한 인력으로 염색이 가능하게 된다. 현재 Cellulose섬유의 상업적인 반응성염료 염색공정뿐만 아니라 최근 연구에서는 전해질 중 대부분 분말망초를 대부분 사용하고 있다. 그러나 분말망초는 별도의 용해과정이 필요할 뿐 아니라, 과량 사용시 용해되지 않은 분말이 섬유 표면에 흡착될 경우 불균염을 초래할 우려 등의 단점이 있다. 이와 같이 작업효율성을 향상시키고 염색을 효율적으로 진행시키기 위해 최근 액상형의 망초가 도입되고 있다. 이 연구에서는 분말 및 액상 망초를 조제로 사용하여 3종류의 Cellulose섬유를 반응성염료로 염색하였다. 담색, 중색, 농색 3가지 염료 농도에 대해 투입하는 망초의 type에 따라 각각의 Cellulose섬유별 균염성 정도에 대하여 비교해 보았다.

• Korean Journal of Food Science and Technology
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• v.50 no.2
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• pp.191-197
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• 2018

This study investigated the influence of starch extraction (ST-EX) solutions on the extraction yield and characteristics of Chinese yam (CY) starches from domestic Dioscorea batatas. Ascorbic acid (VitC), $Na_2S_2O_3$, $NaHCO_3$, and $Na_2CO_3$ were used as ST-EX solutions (0.4%, w/v). The extracted CY starches were examined for ST-EX yield, chemical composition, size distribution, X-ray diffraction, solubility, swelling power, gelatinization, and pasting viscosity. The highest ST-EX yield was obtained from $NaHCO_3$, followed by VitC. Lower protein content, relative crystallinity, and gelatinization enthalpy were found in CY starches from alkaline ST-EX solutions ($NaHCO_3$ and $Na_2CO_3$). Size distribution and gelatinization temperature did not generally differ for CY starches from the different ST-EX solutions. Pasting viscosities increased in the order from $Na_2CO_3$ > $Na_2S_2O_3$ > $NaHCO_3$ > VitC ST-EX solutions. Thus, VitC may be most appropriate to extract CY starch from Dioscorea rhizomes, considering its ST-EX yield, total starch content, and variation in pasting viscosity.

• Korean Journal of Food Science and Technology
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• v.54 no.1
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• pp.75-79
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• 2022

Fresh, washed ginseng can be contaminated with microorganism loads as high as 6.5 log CFU/g for total bacteria and 4.3 log CFU/g for mold. The goal of this study was to test eight antibacterial agents on ginseng. Immersing fresh ginseng washed in 1% (w/w) sodium citrate, sodium diacetate, sodium acetate, citric acid, and sodium lactate solution for 1 h resulted in a bactericidal effect of 31.0-97.5% for total bacteria. Among the organic acids, sodium citrate had the best antibacterial effect, with total bacteria reduced from 6.5 log to 4.9 log CFU/g. A 1% (w/w) vitamin B₁ lauryl sulfate solution with surfactant function by hydrophilic and hydrophobic sites can reduce 2.7 log CFU/g (99.8% inactivation) on total bacteria. In the 1% (w/w) calcium oxide solution, total bacteria were reduced by 3 log, showing an excellent inactivation effect of 99.9%. Calcium oxide is a highly useful material for inactivation of microorganisms in fresh ginseng.

• Analytical Science and Technology
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• v.31 no.1
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• pp.47-56
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• 2018

Finding the blood left at a crime scene is very important to reconstruct or solve a criminal case. Although numerous reagents have been developed for use at crime scenes, luminol is the most representative. Bluestar Forensic has been used in recent years, but is expensive and cannot be stored after preparation. This study aims to develop a new luminol reagent that can be stored for a long period of time while maintaining the chemiluminescence intensity at the level of Bluestar Forensic. Because luminol dissolves well in aqueous alkaline solutions, the use of sodium hydroxide in the preparation of luminol reagents can promote the decomposition of hydrogen peroxide. Magnesium sulfate, sodium silicate, and potassium triphosphate have been used as hydrogen peroxide stabilizers. The effects of the addition of these substances on the chemiluminescence emission intensity and the storage period of the luminol reagents were confirmed. The addition of a hydrogen peroxide stabilizer was shown to have no significant affect on the chemiluminescence emissions intensity or stabilized pH of the luminol reagent during storage. It also greatly increases the shelf life of the reagents. The use of magnesium sulfate as a hydrogen peroxide stabilizer is the most appropriate. When sodium perborate is used instead of hydrogen peroxide as an oxidizing agent, there is no significant change in the sensitivity and chemiluminescence emissions intensity, but the storage period is shortened. However, after the reaction with blood, the pH of the mixed solution does not increase significantly, and is judged to be more suitable than a reagent made of hydrogen peroxide.

• Journal of Soil and Groundwater Environment
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• v.15 no.1
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• pp.29-38
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• 2010

Batch tests were carried out to examine the influence of the presence of soil and Fe(II) sorption capacity of soil on the ferrous catalyzed sodium persulfate oxidation for the destruction of organic pollutants in the application of in-situ chemical oxidation. Laboratory column tests were also conducted to investigate the transport of oxidant and catalyst in contaminated groundwater. Test results proved that Fe(II) was adsorbed on soil surface, and thus soil behaved as a heterogeneous catalyst, enhancing the naphthalene removal rate up to 50%. Column tests that were conducted with and without dissolved Fe(II) showed that naphthalene removal ratio were 24% and 25%, respectively. The removal efficiency was not enhanced with dissolved Fe(II), since the dissolved Fe(II) flew out of the column as the oxidant progressively injected into the column saturated with Fe(II). It indicates that the injected oxidant could not interact with dissolved Fe(II). But target organic pollutant was degraded in soil column system, implying that sulfate radical was produced by the reaction of dissolved persulfate with Fe(II) adsorbed on soil.