• 멤브레인
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• 제31권6호
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• pp.371-383
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• 2021

음이온 교환막은 수소를 생산할 수 있는 수전해와 수소 연료를 사용하여 전기 에너지를 사용할 수 있는 연료전지 시스템에 사용될 수 있다. 음이온 교환막은 알칼라인 조건에서 수산화 이온(OH^-) 전도를 기반으로 작동한다. 하지만, 음이온 교환막은 상대적으로 낮은 이온 전도도와 알칼라인 안정성을 보이기 때문에 아직 수전해 및 연료전지에 상용화되는 데 한계가 존재한다. 이를 해결하기 위해서는 고분자 구조를 합리적으로 설계하여 새로운 음이온 교환막 소재를 개발하는 것이 필수적이다. 특히, 고분자의 물성, 이온전도도, 그리고 알칼라인 안정성이 우수하게 유지될 수 있도록 고분자 구조 및 합성 방법 등을 제어하여 한다. 음이온 교환막 중에서 Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) 기반의 소재는 상용화 되어 접근이 용이하다. 또한, 다른 고분자에 비해 상대적으로 기계적인 특성 및 화학적 안정성이 높아 음이온 교환막 개발에 자주 사용되고 있다. 본 총설에서는 음이온 교환막에서 사용되는 PPO 기반의 고분자 소재 개발 전략 및 특성에 대해서 소개하고자 한다.

• 대한화학회지
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• 제14권1호
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• pp.65-74
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• 1970

양이온 교환수지와 시트르산 이온($Cit^{3-}$)이 들어있는 용액에서 방사성 알칼리 토류 금속 이온이 수지와 용액 사이에 어떻게 분배되는가를 실온에서 조사함으로써 그들 금속 이온의 시트르산 착물형성에 관한 연구를 하였다. 용매로서 $H_2O$, 아세톤-$H_2O$ 및 에탄올-$H_2O$를 사용하였다. 용액의 pH는 7.2-7.5로 조절하였고 이온 강도는 0.10-0.12로 유지하였다. 본 연구의 결과 $Ba^{++}$과 $Sr^{++}$은 어떤 용매계에서도 1:1착물(M $Cit^-$)을 형성하는 것을 알았다. 그리고 $Ca^{++}$은 수용액에서는 1:1착물을 형성하지만 혼합 용매계에서는 1:1착물(Ca $Cit^-$)과 1:2착물(Ca $Cit_2^{4-}$)을 형성함을 알았다. 그리고 이들 착물의 안정도는 $Ba^{++}\;<\;Sr^{++}\;<\;Ca^{++}$ 의 순으로 커지며 또 혼합용매의 유기 성분의 농도 증가순으로 커짐을 알았다.

• 한국대기환경학회지
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• 제27권4호
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• pp.395-404
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• 2011

Asian dust evens took place in Seoul on 27~28 March and 31 March~1 April 2007, during which the mass and chemical compositions of $PM_{10}$ were measured at urban area in Seoul, Korea. In conjunction with $PM_{10}$ compositions, the behaviors of gas precursors such as CO, $O_3$, $SO_2$, and $NO_2$ and meteorological parameters and air mass trajectories were thoroughly examined. The earlier case was a weak dust incidence which was characterized by elevated concentrations of CO, $SO_2$ and $NO_2$ as well as secondary aerosols. In contrast, the later showed the trait of the dust aerosols associated with high $PM_{10}$ mass and $Ca^{2+}$ concentrations. In general, the fractions of ionic species against mass decreased with increase in dust loading. The ratios of ${SO_4}^{2-}$ to ${NO_3}^-$ and $SO_2$ to $NO_2$ were similar in temporal variations, suggesting the concentrations of secondary aerosols were sensitive to the level of precursor gases. In this study, $Na^+$ and $Cl^-$ were also highly elevated during the heavy dust episode, which is thought to have originated from alkaline soils spreading through the northeast regions of China.

• Molecules and Cells
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• 제42권6호
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• pp.460-469
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• 2019

Bacterial ${\alpha}-type$ carbonic anhydrase (${\alpha}-CA$) is a zinc metalloenzyme that catalyzes the reversible and extremely rapid interconversion of carbon dioxide to bicarbonate. In this study, we report the first crystal structure of a hyperthermostable ${\alpha}-CA$ from Persephonella marina EX-H1 (pmCA) in the absence and presence of competitive inhibitor, acetazolamide. The structure reveals a compactly folded pmCA homodimer in which each monomer consists of a 10-stranded ${\beta}-sheet$ in the center. The catalytic zinc ion is coordinated by three highly conserved histidine residues with an exchangeable fourth ligand (a water molecule, a bicarbonate anion, or the sulfonamide group of acetazolamide). Together with an intramolecular disulfide bond, extensive interfacial networks of hydrogen bonds, ionic and hydrophobic interactions stabilize the dimeric structure and are likely responsible for the high thermal stability. We also identified novel binding sites for calcium ions at the crystallographic interface, which serve as molecular glue linking negatively charged and otherwise repulsive surfaces. Furthermore, this large negatively charged patch appears to further increase the thermostability at alkaline pH range via favorable charge-charge interactions between pmCA and solvent molecules. These findings may assist development of novel ${\alpha}-CAs$ with improved thermal and/or alkaline stability for applications such as $CO_2$ capture and sequestration.

• 전기화학회지
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• 제3권2호
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• pp.69-71
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• 2000

카르복시산과 이황하물 다리를 가지며 산화환원 활성이 있는 칼릭스[4]아렌을 합성하였고 그것이 은과 금 표면 위에 자발적으로 흡착하는 것을 관찰하였다. 칼릭스[4]아렌은 특이한 구조 때문에 수용액에서 알칼리 토금속이온에 선택적인 친화력을 보인다 한편 둥그런 이온 수용체를 전극 위에 고정시켰을 때 금속 이온을 포획하는 것을 전압전류법 및 분광학적인 연구를 통해 확인하였다. 아울러 EDTA와 같은 강한 킬레이트제를 이용하여 이온을 가역적으로 제거할 수 있음을 보였다.

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1292-1295
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• 2006

세 종류의 전해질 수용액(염화암모늄형, 염화아연형, 알칼리형)과 조해성재료($CaBr_2$ 또는 $CaCl_2$)를 filter paper 내부에 함침시켜 망간 일차전지용 전해질막을 제조하였다. 전해질막의 두께는 $250{\sim}300{\mu}m$ 이며 유연성 또한 매우 좋았다. 전해질막의 전기화학적 특성은 수분공급을 위해 첨가된 조해성 재료의 종류 및 함량에 크게 의존하였고, $CaCl_2$가 첨가된 계에서 상대적으로 높은 이온전도도 및 방전용량이 얻어졌다.

• 한국산업융합학회 논문집
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• 제21권6호
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• pp.395-408
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• 2018

Even after the Fukushima nuclear accident in 2011, the rate of production of electric energy using nuclear energy is increasing, but there is a great danger such as the radioactive waste produced when using nuclear power, the catastrophic accident of nuclear power plant, and connection with nuclear weapons. In particular, Cs present in the ionic form of alkaline elements has a long half-life (30.17 years) because it is readily absorbed by the organism and emits intense gamma rays, thus presenting a serious radiation hazard. Therefore, it must be completely removed before it can be released into the natural ecosystem, because it can adversely affect not only humans but also natural ecosystems. Many adsorbents and ion exchangers which have high Cs removal efficiency have been used in recent years to completely separate and remove by self separation in water. Many adsorbents and ion exchangers which have high Cs removal efficiency have been used in recent years to completely separate and remove by self separation in water. In addition, researches have been doing to synthesize magnetic materials with adsorbents such as HCF and PB, and it shows a great effect in the removal rate of Cs present in wastewater or the maximum Cs adsorption amount. In particular, when a magnetic material was applied, excellent results were obtained in which only Cs was selectively removed from other cations. However, new problems such as applicability in the sea where Cs is directly released, applicability in various pH ranges, and failure to preserve the magnetizing force possessed by the magnetic body have been found. However, researches using ferromagnetic field with stronger magnetic properties than those of magnetic bodies is considered to be insufficient. Therefore, it is considered that if the researches combining the ferromagnetic field with the magnetization ability and functional adsorbents more actively, the radioactive material Cs which adversely affects the natural ecosystem can be effectively removed.

• Journal of Ecology and Environment
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• 제37권3호
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• pp.131-137
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• 2014

To investigate the solute pattern of salt marsh plants in Suncheon Bay in Korea, plants and soil samples were collected at three sites from July to September 2011. The soil pH around the investigated species was weakly alkaline, 6.9-8.1. The total ion and Cl- content of site 1 gradually increased, while those of site 2 and site 3 were lowest in August and highest in September. The exchangeable $Ca^{2+}$, $Mg^{2+}$ and $K^+$ in the soil were relatively constant during the study period, but the soil exchangeable $Na^+$ content was variable. Carex scabrifolia and Phragmites communis had constant leaf water content and very high concentrations of soluble carbohydrates during the study period. However, Suaeda malacosperma and S. japonica had high leaf water content and constant very low soluble carbohydrate concentrations. Carex scabrifolia accumulated similar amounts of $Na^+$ and $K^+$ ions in its leaves. Phragmites communis contained a high concentration of $K^+$ ions. Suada japonica and S. malacosperma had more $Na^+$ and $Cl^-$ ions than $K^+$ ions in their leaves. Suaeda japonica had higher levels of glycine betaine in its leaves under saline conditions than C. scabrifolia and P. communis. Consequently, the physiological characteristics of salt marsh chenopodiaceous plants (S. japonica and S. malacosperma) were the high storage capacity for inorganic ions (especially alkali cations and chloride) and accumulation of glycine betaine, but monocotyledonous plant species (C. scabrifolia and P. communis) showed high $K^+$concentrations, efficient regulation of ionic uptake, and accumulation of soluble carbohydrates. These characteristics might enable salt marsh plants to grow in saline habitats.

• 한국환경과학회지
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• 제8권3호
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• pp.411-417
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• 1999

The interfacial chemical behavior, lattice exchange and dissolution, of $FeS_{(S)}$ as one of the important sulfide minerals was studied. Emphases were made on the surface characterization of hydrous $FeS_{(S)}$, the lattice exchange of Cu(II) and $FeS_{(S)}$, and its effect on the dissolution of $FeS_{(S)}$, and also affect some organic ligands on that of both Cu(II) and $FeS_{(S)}$. Cu(II) which has lower sulfide solubility in water than $FeS_{(S)}$ undergoes the lattice exchange reaction when Cu(II) ion contacts $FeS_{(S)}$ in the aqueous phase. For heavy metals which have higher sulfide solubilities in water than $FeS_{(S)}$, these metal ions were adsorbed on the surface of $FeS_{(S)}$. Such a reaction was interpreted by the solid solution formation theory. Phthalic acid(a weak chelate agent) and EDTA(a strong chelate agent) were used to demonstrate the effect of organic lignads on the lattice exchange reaction between Cu(II) and $FeS_{(S)}$. The $pH_{zpc}$ of $FeS_{(S)}$ is 7 and the effect of ionic strength is not showed. It can be expected that phthalic acid has little effect on the lattice exchange reaction between Cu(II) and $FeS_{(S)}$. whereas EDTA has very decreased the removal of Cu(II) and $FeS_{(S)}$. This study shows that stability of sulfide sediments was predicted by its solubility. The pH control of the alkaline-neutralization process to treat heavy metal in wastewater treatment process did not needed. Thereby, it was regarded as an optimal process which could apply to examine a long term stability of marshland closely in the treatment of heavy metal in wastewater released from a disussed mine.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.244-254
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• 2018

Surface modified poly ${\text\tiny{L}}$-lactic acid (PLLA) samples with hydroxyapatite (HA), heparin and bone morphogenetic protein-2 (BMP-2) mediated by polydopamine (pDA) coating (PLLA/pDA/HA/Hep/BMP-2) were prepared, and their effects on the enhancements of bone formation and osseointegration were evaluated in vitro and in vivo as compared to PLLA, PLLA/pDA/HA, and PLLA/pDA/Hep/BMP-2. The changes in surface chemical compositions, morphologies and wettabilities were observed by X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and water contact angle measurements. Pre-coating of HA particles with pDA provided uniform and homogeneous anchoring of particles to PLLA surface. In addition, the strong ionic interaction between heparin and pDA led PLLA surface readily heparinized for loading of BMP-2. In vitro experiments revealed that the levels of alkaline phosphatase (ALP) activity, calcium deposition, and osteocalcin (OCN) gene expression were higher in MG-63 human osteosarcoma cell lines grown on PLLA/pDA/HA/Hep/BMP-2 than on control PLLA, PLLA/pDA/HA, and PLLA/pDA/Hep/BMP-2. In vivo studies using micro-computed tomography (micro-CT) also showed that PLLA/pDA/HA/Hep/BMP-2 screw exhibited greatest value of bone volume (BV) and bone volume/tissue volume (BV/TV) among samples. Histological evaluations with H&E and Von Kossa staining demonstrated that a combination of HA and BMP-2 contributed to the strong osseointegration.