• Bulletin of the Korean Chemical Society
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• 제20권5호
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• pp.556-558
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• 1999

Lead-selective PVC membrane electrodes based on newly synthesized bis(crown ether)s containing 18-crown-6 moiety was prepared using standard PVC membrane composition. In order to monitor lead in environmental samples by lead sensor, especially good selectivity over alkali and alkaline earth metals has to be obtained. Thus, responses of the PVC membrane prepared with new bis(crown ether)s and Fluka ionophore V (crown ether) base to various cations include lead, alkali and alkaline earth metal ions were investigated for their use as a lead sensor. The polymeric liquid membrane based on trans-1 8-crown-6 ether exhibits the best overall potentiometric performances as a lead-selective electrode in terms of a wide linear dynamic range (between 10-6 and 10-2 M, Pb2+), excellent detection limit (less than 10-6 M) and good durability within limited error. The preferences of lead over other cations, such as Ag+, Hg2+, Na+, Ca2+ and even K+ in the aforementioned electrode are much better than the Fluka ionophore V system.

• Journal of the Korean Wood Science and Technology
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• 제24권3호
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• pp.51-56
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• 1996

The Bark lignin(alkali- and acid lignin), bark extractives(hot water-and $Na_2SO_3$ extractives) of Quercus acutissima and Pinus densiflora, and flavonoids were used to detect heavy metal adsorption. The adsorption ratio of heavy metals by lignin was assigned for 40 to 50%, but was not dependent on lignin kinds. However, in case of the addition of light metals such as $Ca^{++}$ and $Mg^{++}$ to lignin the adsorption ratio was increased by 20 to 40%, and $Pb^{++}$ was almost completely adsorbed. On hot water extractives, the adsorption ratio was very low because the substrate was water-soluble, so the substrate should be water-insoluble to adsorb the heavy metals. However, the adsorption ratios of $Cd^{++}$ and $Pb^{++}$ on $Na_2SO_3$ extractives were significantly increased, while those of $Zn^{++}$ and $Cu^{++}$, were similar to lignin. When four kinds of heavy metals were treated to $Na_2SO_3$ extractives together, more than 97% of $Pb^{++}$ and $Cu^{++}$ was adsorbed_ and $Zn^{++}$ was more adsorbed by 40%, and $Cd^{++}$ was not changed, comparing with the case that on kind of heavy metal was treated. There were differences between adsorption ratio of the kinds of flavonoids and heavy metals, and the adsorption ratio of heavy metals was assigned to 20 to 45% per 0.1g flavonoid.

• 인간식물환경학회지
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• 제24권6호
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• pp.585-593
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• 2021

Background and objective: Illegal open-air incineration, which is criticized as a leading source of air pollutants among agricultural activities, currently requires constant effort and attention. Countries around the world have been undertaking studies on the emission of heavy metal substances in fine dust discharged during the incineration process. A precise analytical method is required to examine the harmful effects of particulate pollutants on the human body. Methods: In order to simulate open-air incineration, the infrastructure needed for incineration tests complying with the United States Environmental Protection Agency (EPA) Method 5G was built, and a large-area analysis was conducted on particulate pollutants through automated scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS). For the test specimen, high-density polyethylene (HDPE) waste collected by the DangJin Office located in Choongcheongnam-do was used. To increase the identifiability of the analyzed particles, the incineration experiment was conducted in an incinerator three times after dividing the film waste into 200 g specimens. Results: Among the metal particulate matters detected in the HDPE waste incineration test, transition metals included C (20.8-37.1 wt%) and O (33.7-37.9 wt%). As for other chemical matters, the analysis showed that metal particulate matters such as metalloids, alkali metals, alkaline earth metals, and transition metals reacted to C and C-O. Si, a representative metalloid, was detected at 14.8-20.8 wt%, showing the highest weight ratio except for C and O. Conclusion: In this study, the detection of metal chemicals in incinerated particulate matters was effectively confirmed through SEM-EDS. The results of this study verified that HDPE waste adsorbs metal chemicals originating from soil due to its own properties and deterioration, and that when incinerated, it emits particulate matters containing transition metals and other metals that contribute to the excessive production and reduction of reactive oxygen species.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권6호
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• pp.431-435
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• 2000

The goal of this research is to compare the metal binding characteristics of an anoxic selector activated sludge system and a conventional activated sludge system. Metal biosorption by biomass harvested from experimental systems was determined by a series of batch experiments. Heavy metals studied in this research were zinc, cadmium, and nickel. The sorption isotherm showed that the selector sludge had significantly higher sorption capacity than did the control sludge. Metal biosorption behavior closely followed a Freundlich isotherm model for equilibrium concentrations. ECP contents of biomass estimated by alkali extraction technique showed that ECP levels in the selector sludge significantly higher than that in the sludge harvested from the conventional system, indicating that the higher metal sorption capacity of selector sludge may be due to the selection of the ECP-producing bacteria (i.e., Zoogloea sp.) by the selector system.

• 분석과학
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• 제32권4호
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• pp.121-130
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• 2019

Alumina is one of the most important ceramic materials because of its useful physical and chemical properties. Recently, high-purity alumina has been used in various industrial fields. This leads to increasing demand for reliable elemental analysis of impurities in alumina samples. However, the chemical inertness of alumina makes the sample preparation for conventional elemental analysis a tremendously difficult task. Herein, we demonstrated the feasibility of laser ablation for effective sampling of alumina powder. Laser ablation performs sampling rapidly without any chemical reagents and also allows simultaneous optical emission spectroscopy and mass spectrometry analyses. For six alumina samples including certified reference materials and commercial products, laser-induced breakdown spectroscopy (LIBS) and laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) analyses were performed simultaneously based on a common laser ablation sampling. LIBS was found to be useful to quantify alkali and alkaline earth metals with limits-of-detection (LODs) around 1 ppm. LA-ICP-MS could quantify transition metals such as Ti, Cu, Zn, and Zr with LODs in the range from a few tens to hundreds ppb.

• 공업화학
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• 제29권1호
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• pp.112-116
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• 2018

주조공정 중 주형제조 시 점결제로 사용되는 silicate계 바인더의 주요원료 중 하나인 물유리와 첨가제(Si, 알칼리 금속)의 혼합특성을 살펴보았다. 물유리와 첨가제 그리고 비율에 따라 제조된 혼합물은 FT-IR분석을 통해 분자결합구조를 살펴보았으며, 점도측정으로 분자구조와의 상관관계를 비교하였다. 물유리에 Si 소스의 제공은 물질 내 Si 망상결합을 촉진시켜 점도는 증가하였고, 알칼리 금속을 첨가하였을 경우에 물유리의 Si 망상결합을 억제하여 점도가 낮아졌다. 물유리와 리튬 실리케이트(lithium silicate, LS)의 혼합물의 점도는 LS의 함량이 20 wt% 이하에서는 LS의 함량이 증가할수록 증가하였지만, 20 wt%를 초과할 경우 점차 낮아졌다. 물유리에 KOH를 첨가함으로써 점도를 낮출 수 있었으며, 콜로이달 실리카(colloidal silica, CS) 또는 potassium methyl siliconate (PMS)와의 혼합을 효과적으로 이용하는 데 이용할 수 있다.

• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1260-1264
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• 2005

Three new quaternary tantalum thiophosphates, $K_{0.18}TaPS_6,\;K_{0.28}TaPS_6,\;and\;Rb_{0.09}TaPS_6$ have been synthesized by using reactive alkali metal halide fluxes and structurally characterized by single crystal X-ray diffraction techniques. The crystal structures of $K_{0.18}TaPS_6,\;K_{0.28}TaPS_6,\;and\;Rb_{0.09}TaPS_6$ contain 3-dimensional open framework anions, $[TaPS_6]^{x-}$(x = 0.09, 0.18, 0.28) with the empty channel which disordered alkali metal cations, $K^+\;and\;Rb^+$ are located in. Crystal data: $K_{0.18}TaPS_6$, tetragonal, space group$I4_1$/acd (no. 142), a=15.874(3) $\AA$, c=13.146(4) $\AA$, V=3312.7(12) ${\AA}^3$, K, Z=16, R1=0.0545. Crystal data: $K_{0.28}TaPS_6$, tetragonal, space group $I4_1$/acd (no. 142), a=15.880(2) $\AA$, c=13.134(3) $\AA$, V=3312.1(10) ${\AA}^3$, Z=16, R1=0.0562. Crystal data: $Rb_{0.09}TaPS_6$, tetragonal, space group I41/acd (no. 142), a=15.893(3) $\AA$, c=13.163(4) $\AA$, V=3324.7(15) ${\AA}^3$, Z=16, R1=0.0432.

• 한국농공학회논문집
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• 제58권3호
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• pp.39-46
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• 2016

This study investigated the potential use and the effectiveness of biomass ashes for the stabilization of heavy metals in soil through a series of experiments. The ashes used for the experiments were obtained from the gasification of biomass including miscanthus and woodchips. The amounts of nickel and chromium released from the soil and ash mixture were analyzed. Chemical analysis showed that the ash contained unburned carbon as well as silica and alkali metals. Miscanthus ashes have C (83.400 %) > Si (9.040 %) > K (3.180 %) > Ca (1.800 %), and woodchip ashes have C (93.800 %) > Ca (2.220 %) > Fe (1.370 %) > K (1.200 %). KSLT and TCLP test results implied that the heavy metal concentrations were below the environmental standards and would not impose the risks. The results also showed that Ni releases were more limited as more ashes were mixed with the soil due to the increases in exchangeable, carbonate, and oxide nikels. Both miscanthus and woodchip ahses were effective in stabilizing nickel and chromium through mixing with the soil. It could be seen that ashes produced from biomass gasification can be used to stabilize the heavy metals in soils.

• 유기물자원화
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• 제15권4호
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• pp.107-114
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• 2007

다당류의 일종인 알긴산을 이용한 중금속 제거에 관한 연구가 수행되어졌다. 알긴산은 pH 4에서 480mg/g의 납 이온을 흡착하였으며 이것은 다른 생물흡착제에 비해서 약 2배 정도의 높은 흡착능이다. 납 이온에 대한 등온흡착선을 묘사하기 위하여 Langmuir model 식을 이용하였으며 실험결괴는 모델식에서 얻어진 결과와 잘 부합되었다. 온도가 증가함에 따라서 흡착능은 증가하였으며 이는 알긴산과 납 이온의 흡착은 흡열반응임을 보여준다. 납 이온의 흡착에 대한 알칼리 금속(칼슘, 마그네슘 이온)의 영향은 거의 없었으며 대부분의 흡착은 30분 내에 이루어졌다. 구리, 수은, 스트론튬, 세슘 과 같은 다른 금속 이온에 대한 흡착능도 조사되었다.

• Journal of Information Display
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• 제13권3호
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• pp.113-118
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• 2012

Metal oxide semiconductors were considered promising materials as backplanes of future displays. Moreover, the adoption of carrier-suppressing metal into indium-zinc oxide (IZO) has become one of the most important themes in the metal oxide research field. In this paper, efforts to realize and optimize IZO with diverse types of carrier suppressors are summarized. Properties such as the band gap of metal in the oxidized form and its electronegativity were examined to confirm their relationship with the metal's carrier-suppressing ability. It was concluded that those two properties could be used as indicators of the carrier-suppressing ability of a material. As predicted by the properties, the alkali earth metals and early transition metals used in the research effectively suppressed the carrier and optimized the electrical properties of the metal oxide semiconductors. With the carrier-suppressing metals, IZO-based thin-film transistors with high (above $1cm^2/V{\cdot}s$) mobility, a lower than 0.6V/dec sub-threshold gate swing, and an over $3{\times}10^6$ on-to-off current ratio could be achieved.