• 멤브레인
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• 제16권1호
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• pp.25-30
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• 2006

[ ${\alpha}$ ]-알루미나 튜브 지지체의 내부에 1Si : 1Na : 4Na : $6H_{2}O$의 비율로 제조한 합성 용액을 사용하여 수열합성법으로 NaA 제올라이트 분리막을 제조하였다. 합성된 제올라이트 분리막을 이용하여 iso-propyl alcohol (IPA)/물 혼합물의 조성비와 조업 온도 변화에 따른 선택도와 투과도의 변화를 알아보기 위한 투과증발 실험을 수행하였다. 총투과도는 공급 측 IPA의 농도가 증가함에 따라 감소하였고, 온도가 상승함에 따라 증가하는 경향을 보였다. 총투과도는 $60^{\circ}C$에서 공급물의 IPA농도가 0.6 몰분율일 때 $4.0{\times}10^3g/m^2\;hr$로 가장 높은 값을 보였다. 선택도는 IPA의 몰비가 0.8까지 증가하는 경향을 보였고 0.9 이상에서 감소하는 경향을 나타내었다 선택도는 $60^{\circ}C$, 0.8 몰분율에서 $1.8{\times}10^7$의 값으로 최고치를 나타내었다. NaA 제올라이트 분리막을 이용한 투과증발은 기존의 증류공정과 비교 시 훨씬 우수한 선택적 물 분리 성능을 나타내었다.

• 한국대기환경학회지
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• 제2권2호
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• pp.9-18
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• 1986

For identification and apportionment of sources emitting particulate matters in environment, the multi-elemental characterization of size-density fractionated particulate matters was carried out. Eight types of samples were tested; soil, flyash released from burning of bunker-Coil, diesel oil, coal, and soft coal, urban road-way dust, urban dust fall, and airborne particulate matter. The fractions of particulate matters obtained by heavy liquid separation methos with a series of dichloromethane-bromoform were then analyzed using atomic absorption spectrophotometry for Ni, Cr, Cu, An, Fe, Al, and Mg. Each sample showed a different concentration profile as a function of density, and a number of useful conclusions concerning characterization of elemental distribution were obtained. From the density distributions of elements in soil, the maximum value was found for all elements in the density range of 2.2 $\sim 2.9g.cm^{-3}$, including the density of $SiO_2$. However, the distribution of metallic compounds with the density lower than $2.2g.cm^{-3}$ was prevalent in urban roadway dust, urban dust fall, and airborne particulate matter. And the density distribution curves of these urban dusts also have the higher distribution at the density of 2.2 - 2.9g.cm^{-3}$, including the density of wind-blown silica. This tendency generally was prevalent in the natural source elements, such as Al, Fe, Mn, and Mg. The maximum values were found in the density ranges of 1.3 $\sim 2.2g.cm^{-3}$ from the density distribution of elements in oil fired flyash. These distributions of anthropogenic source elements, such as Zn, Ni, Cu, and Cr were higher predominately than those of natural source elements. And the higher distribution was found in the density range of $2.2 \sim 2.9g.cm^{-3}$ from the density distribution of elements in coal and soft-coal fired flyash. These distributions showed similar patterns to soil. But anthropogenic source elements somewhat predominated at the density ranges of $1.3 \sim 2.2g.cm{-3} and 2.9g.cm^{-3}$ to soil. Therefore the higher distribution of anthropogenic source elements in the density ranges of $1.3 \sim 2.2g.cm^{-3} and 2.9g.cm^{-3}$ was considered as anthropogenic origin.

• Nuclear Engineering and Technology
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• 제49권8호
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• pp.1711-1716
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• 2017

Uranium tetrafluoride ($UF_4$) is the most used nuclear material for producing metallic uranium by reduction with Ca or Mg. Metallic uranium is a raw material for the manufacture of uranium silicide, $U_3Si_2$, which is the most suitable uranium compound for use as nuclear fuel for research reactors. By contrast, ammonium uranyl carbonate is a traditional uranium compound used for manufacturing uranium dioxide $UO_2$ fuel for nuclear power reactors or $U_3O_8-Al$ dispersion fuel for nuclear research reactors. This work describes a procedure for recovering uranium and ammonium fluoride ($NH_4F$) from a liquid residue generated during the production routine of ammonium uranyl carbonate, ending with $UF_4$ as a final product. The residue, consisting of a solution containing high concentrations of ammonium ($NH_4^+$), fluoride ($F^-$), and carbonate ($CO_3^{2-}$), has significant concentrations of uranium as $UO_2^{2+}$. From this residue, the proposed procedure consists of precipitating ammonium peroxide fluorouranate (APOFU) and $NH_4F$, while recovering the major part of uranium. Further, the remaining solution is concentrated by heating, and ammonium bifluoride ($NH_4HF_2$) is precipitated. As a final step, $NH_4HF_2$ is added to $UO_2$, inducing fluoridation and decomposition, resulting in $UF_4$ with adequate properties for metallic uranium manufacture.

• 공업화학
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• 제17권3호
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• pp.235-242
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• 2006

Liquid phase alkylation of biphenyl (BP) was studied over large pore zeolites. Selective formation of the least bulky products, 4,4'-diisopropylbiphenyl (4,4'-DIPB) occurred only in the isopropylation of BP over some large pore molecular sieves. H-mordenites (MOR) gave the highest selectivity among them. The dealumination of MOR enhanced catalytic activity and the selectivity of 4,4'-DIPB because of the decrease of coke-deposition. Non-selective catalysis occurs on external acid sites over MOR with the low $SiO_2/Al_2O_3$ ratio because severe coke-deposition deactivates the acid sites inside the pores by blocking pore openings. The selectivity of DIPB isomers was changed with reaction temperature. Selective formation of 4,4'-DIPB was observed at moderate temperatures such as $250^{\circ}C$, whereas the decrease of the selectivity of 4,4'-DIPB occurred at higher temperatures as $300^{\circ}C$. However, 4,4'-DIPB was almost exclusive isomer in the encapsulated DIPB isomers inside the pores even at high temperatures. These decreases of the selectivity of 4,4'-DIPB are due to the isomerization of 4,4'-DIPB on the external acid sites. Some 12-membered molecular sieves, such as SSZ-24, MAPO-5 (M:Mg, Zn, Si), SSZ-31, and ZSM-12, which have straight channels, gave 4,4'-DIPB with moderate to high selectivity; however; SSZ-55, SSZ-42, and MAPO-36 (M: Mg, Zn) gave lower selectivity because of cages in 12-membered one dimensional channels. Three dimensional H-Y and Beta zeolites also yield 4,4'-DIPB in low yield because of their wide circumstances for the isopropylation of BP. The increasing the size of alkylating agent enhanced the shape-selective alkylaiton even for the zeolites, such as UTD-1. The ethylation of BP to ethylbiphenyls (EBPs) and diethylbiphenyls (DEBPs) over MOR was non-selective. The ethylation of BP to EBPs was controlled kinetically. However, there was difference in reactivity of EBPs and DEBPs for their further ethylation. 4-EBP was ethylated preferentially among the isomers, although the formation of 4,4'-DEBP was less selective. The least bulky 4-EBP and 4,4'-DEBP have the highest reactivity among EBPs and DEBPs for the ethylation to polyethylbiphenyls (PEBPs). These results show that the environments of MOR pores are too loose for shape selective formation of the least bulky isomers, 4-EBP and 4,4'-DEBP in the ethylation of BP, and that MOR pores have enough space for the further ethylation of 4,4'-DEBP.

• 공업화학
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• 제35권4호
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• pp.303-308
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• 2024

리튬 이차 전지는 고에너지 및 친환경 특성으로 인해 전기 자동차, energy storage system (ESS) 등의 중대형 에너지원으로의 활용이 대두되고 있다. 현재 상용화되고 있는 리튬 이차 전지의 특성은 고에너지 밀도 및 안전성에 대한 요구를 완전히 충족시키지는 못하고 있다. 이러한 요구들을 충족하기 위해 고체 전해질에 대한 많은 연구가 이루어지고 있다. 고체 전해질을 상용화하기 위해서는 유기 액체 전해질에 비해 낮은 이온전도도와 높은 전극과의 계면 저항을 극복하는 것이 중요한 과제이다. 이에 본 연구에서는 이온전도성을 가지면서 수산기를 갖고 있어 전극과의 접착성이 좋은 고분자인 poly(vinyl alcohol) (PVA) 매트릭스에 oligo(3,4-ethylenedioxythiophene) (oligo(EDOT))을 첨가하여 동종의 polythiophene (PTh) 기반 전극과의 계면 저항을 낮추고, 다공성 silicon dioxide (SiO₂) filler를 첨가하여 리튬 염 해리능력을 향상시켜 이온전도도를 높인다. 그리고 첨가제로 인해 낮아진 고체 전해질의 기계적 특성을 boric acid (BA)를 사용하여 가교 구조를 도입함으로써 전기화학적 안정성을 향상시킨다.

• 자원리싸이클링
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• 제31권1호
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• pp.21-28
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• 2022

폐리튬이온배터리를 고온에서 용융환원시키면 코발트, 니켈 및 구리 금속합금상을 얻을 수 있다. 이러한 금속합금상으로부터 금속을 분리회수하기 위한 공정을 개발하기 위해 코발트, 니켈 및 구리 금속을 혼합한 금속혼합물을 3% 과산화수소를 함유한 2 M 황산용액으로 침출하면 9.6%의 구리와 함께 코발트와 니켈이 모두 침출된다. 침출용액에서 Cyanex 301로 구리(II)가 선택적으로 추출되었으며, 30% 왕수로 구리(II)를 탈거했다. 구리가 분리된 여액에서 이온성액체인 ALi-SCN으로 Co(II)를 선택적으로 추출했으며, 15%의 암모니아용액으로 3단의 교차식 탈거를 통해 모두 탈거했다. 본 연구를 통해 코발트, 니켈 및 구리 금속혼합물의 황산침출액에서 용매추출로 세 금속을 분리할 수 있는 공정을 제안했다.

• Advances in materials Research
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• 제9권3호
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• pp.219-231
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• 2020

The aim of this study is to investigate the durability of fly ash based geopolymer mortar with and without protective coatings in aggressive chemical environments. The source materials for geopolymer are Fly ash and Ground Granulated Blast furnace Slag (GGBS) and they are considered in the combination of 80% & 20% respectively. Two Molarities of NaOH solution were considered such as 8M and 10M. The ratio of binder to sand and Sodium silicate to Sodium hydroxide solution (Na₂SiO₃/NaOH) are taken as 1:2 and 2 respectively. The alkaline liquid to binder ratio is 0.4. Compressive strength tests were conducted at various ages of the mortar specimens. In order to evaluate the performance of coatings on geopolymer mortar under aggressive chemical environment, the mortar specimens were coated with two different types of coatings such as epoxy and Acrylic. They were then subjected to different chemical environments by immersing them in 10% standard solutions of each ammonium nitrate, sodium chloride and sulphuric acid. Drop in compressive strength as a result of chemical exposure was considered as a measure of chemical attack and the drop in compressive strength was measured after 30 and 60 days of chemical exposure. The compressive strength results following chemical exposure indicated that the specimens containing the acrylic coating proved to be more resistant to chemical attacks. The control specimen without coating showed a much greater degree of deterioration. Therefore, the application of acrylic coating was invariably much more effective in improving the compressive strength as well as the resistance of mortar against chemical attacks. The results also indicated that among all the aggressive attacks, the sulphate environment has the most adverse effect in terms of lowering the strength.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.49.2-49.2
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• 2009

최근, 플루이딕스칩 제작에 있어서 가격이 저렴하며 구조물 형성이 쉽다는 장점으로 인하여 유리 기판을 플라스틱 기판으로 대체하려는 연구가 많이 진행하고 있다. 하지만 플라스틱 기판은 유리 기판에 비하여 많은 장점을 갖고 있음에도 불구하고, 기판 표면이 소수성이기 때문에 유체의 흐름을 저하시키는 문제점이 있다. 기존의 플라스틱 기판을 친수성으로 개질하는 방법으로는 화학적처리, 자외선 조사, 산소플라즈마 처리 등의 방법이 있었으나, 화학적처리 방법은 공정의 민감성과 폐기물로 인한 양산적용의 한계가 있고, 자외선 조사법 및 산소 플라즈마 처리는 친수성이 영구적이지 않다는 결정적인 문제점이 있다. 이는 플라스틱 플루이딕스칩의 신뢰도를 크게 저해하여 상용화에 큰 문제점으로 작용한다. 이러한 문제점을 극복하기 위한 새로운 방법의 친수성 표면처리가 요구되어 지고 있다. 본 연구에서는, 기존 플라스틱 기판의 친수성 표면처리 방법들의 문제점들을 개선하고자 플라스틱 기판의 변형을 야기하지 않는 저온 PE-CVD 방식을 이용하여 균질한 두께의 $SiO_2$박막을 형성 하였으며, 형성된 박막을 liquid self-assembled monolayer(L-SAM)방식을 이용하여 아민 표면으로 개질하였다. 이를 통해, 플라스틱 채널 상에서 유체의 원활한 흐름, 형성된 아민 표면에 단백질 및 DNA와 같은 생체 물질 고정화의 용이성 및 영구적 표면개질의 특성을 얻을 수 있었다. 이뿐만 아니라, 플라스틱 기판 외에도 재료에 관계없이 모든 물질의 표면을 생체 안정성이 뛰어난 친수성 표면으로 개질 할 수 있으며, 알데히드 및 카르복시산 등의 다양한 작용기로 변형이 쉽다는 장점이 있다. 개질된 친수성 표면의 평가를 위하여 시간에 따른 접 촉각 및 형광 스캐너(Fluorescence Scanner)를 이용하여 영구적인 친수성 특성 및 생체물질 적합성을 파악하였다. 또한, L-SAM 조건에 따른 아민의 형성정도를 측정하기 위하여 XPS(X-ray Photoelectron Spectroscopy) 분석을 실시 하였다. 최적화된 표면처리를 실제 플라스틱 플루이딕스칩에 적용하여, 유체의 흐름을 관찰 하였다.

• 대한금속재료학회지
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• 제48권10호
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• pp.893-900
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• 2010

In the present work, the impact loads and their effects on the surface damage under the simultaneous cavitation bubble and solid particle collapses in the sea water have been quantitatively investigated for the austenitic 304 stainless steel by using a vibratory cavitation test device. To do this, angular $SiO_2$ solid particles with an average size of $150{\mu}m$ were dispersed into the test liquid, and the measured impact amplitudes were converted into the impact loads by a steel ball drop test. The maximum impact load was determined to be 28.2 N in the absence of solid particles, but increased to 33.7 N in the presence of solid particles. In addition, the critical impact loads, $L_{crit}$, required to generate pits with sizes greater than $3{\mu}m$ were measured to be 19.6 N and 16.6 N, respectively, for the cavitation bubble collapse and solid particle collapse. As a result of the cavitation erosion test, the incubation time and erosion rate were 1.2 times lower and 1.5 times higher, respectively, by a solid particle collapse compared to those only by the cavitation bubble collapse, indicating a drastic decrease in a resistance to cavitation erosion by the solid particle collapse.

• 접착 및 계면
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• 제20권3호
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• pp.102-109
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• 2019

PET기재 필름 위에 코팅된 다층박막 필름의 층별성분을 ATR FT-IR과 Pyro GC/MS(Gas Chromatography/Mass Spectroscopy)를 이용하여 분석을 시도하였다. 필름의 단면은 액체질소에 담근 후 파괴시켜 얻었으며 광학 현미경을 이용하여 관찰하였다. 이 결과 코팅층의 총 두께는 $70{\mu}m$였으며 3개의 층으로 관찰되었다. 각 층의 두께는 너무 얇기 때문에 표면층을 제외하고는 직접분석이 어려워 적절한 용매로서 각 층을 드러나게 한 후 ATR FT-IR과 pyro-GC/MS를 이용하여 분석을 시도하였다. 이 결과 3개 층은 공통적으로 우레탄-아크릴레이트 공중합체로 밝혀졌다. 또한 무기 혹은 금속성분의 첨가여부는 XPS와 SEM-EDAX를 이용하여 분석하였으며 도장층 (1)에는 나노크기의 실리카 입자가 도장층 (2)에서는 알루미늄 박편이 존재함을 알게 되었다.