• 한국환경과학회지
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• 제21권4호
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• pp.421-435
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• 2012

Novel $N_2O_2$ tetradentate ligands, H-3BPD and H-2BPD were synthesized. Hydrochloric acid salts of Br-3BPD, Cl-3BPD, Br-2BPD and Cl-2BPD having Br and Cl substituents at the $para$ position of the phenol hydroxyl group, were synthesized. The ligands were characterized by C. H. N atomic analysis, $^1H$ NMR, $^{13}C$ NMR, UV-visible, and mass spectra. The proton dissociation constants ($logK_n{^H}$) of the phenol hydroxyl group and secondary amine of the synthesized $N_2O_2$ ligands were shown by four step wise values. The orders of the calculated overall proton dissociation constants ($log{\beta}_p$) were Br-3BPD < Cl-3BPD < H-3BPD in case of 3BPD and Br-2BPD < Cl-2BPD < H-2BPD in case of 2BPD respectively. The order agreed well with that of $para$ Hammett substituent constants(${\delta}_p$). The stability constants($logK_{ML}$) of the complexes between the synthesized ligands and transition metal(II) ions agreed with the order of $log{\beta}_p$ of the ligands. The order of the $logK_{ML}$ value of the each transition metal (II) ion was Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II), which agreed well with that of Iriving-Williams series.

• Advances in environmental research
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• 제5권2호
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• pp.125-140
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• 2016

The paper is focused on the economic analysis of two hydrometallurgical processes for recovery of yttrium and other rare earth elements (REEs) from fluorescent phosphors of spent lamps. The first process includes leaching with sulphuric acid and precipitation of a mixture of oxalates by oxalic acid, the second one includes leaching with sulphuric acid, solvent extraction with D2EHPA, stripping by acid and recovery of yttrium and traces of other rare earths (REs) by precipitation with oxalic acid. In both cases the REEs were recovered as oxides by calcination of the oxalate salts. The economic analysis was estimated considering the real capacity of the HydroWEEE mobile's plant ($420kg\;batch^{-1}$). For the first flow-sheet the cost of recycling comes to $4.0{\euro}kg^{-1}$, while the revenue from the end-product is around $5.40{\euro}kg^{-1}$. The second process is not profitable, as well as the first one, taking into account the composition of the final oxides: the cost of recycling comes to $5.2{\euro}kg^{-1}$, while the revenue from the end-product is around $3.56{\euro}kg^{-1}$. The process becomes profitable if the final RE oxide mixture is sold for nearly $50{\euro}kg^{-1}$, a value rather far from the current market prices but not so unlikely since could be achieved in the incoming years, considering the significant fluctuations of the Res' market.

• 보존과학회지
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• 제29권4호
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• pp.421-435
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• 2013

본 연구는 수중 발굴 도자기에 있어 상대습도 조건에 따른 수용성 염의 표면거동을 조사하여 도자기 보존관리에 적합한 환경기준을 제시하고자 한다. 실험 24주간 전기전도도 누적총량(${\mu}s/cm$)으로 [고습조건(RH70%+RH80%)/저습조건(RH20%+RH40%)]의 상대적 비율 분석결과, 고습조건이 저습조건에 비해 이온용출량이 증가하였고, 특히 청자 시료의 경우 그 증가폭이 두드러졌다. 또한 고습조건 시편들의 전기전도도 누적총량을 시료의 물리적 특성과 비교한 결과, 이온용출량은 시료의 흡수율 및 기공률의 증가에 따라 비례하였다. 수중 발굴 도자기는 매장환경의 특성상 염에 의한 물리 화학적 손상 및 2차오염이 크게 우려된다. 따라서 도자기의 이상적인 보존에는 습도변화에 비교적 안정적인 저습조건의 항온항습 수장고가 권장되며, 수장고 설비에 있어 시료의 재질특성에 따른 사전분류가 선행될 필요가 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1229-1232
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• 1994

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li secondary battery. This paper describes the effects of lithium salts, plasticizer addition and temperature dependence of conductivity of PEO electrolytes. Polyethylene oxide(PEO) based polymer electrolyte films were prepared by solution casting an acetonitrile solution of preweighed PEO and Li salt. After solvent evaporation, the electrolyte films were vacuum-dried at $60^{\circ}C$ for 48h, the thickness of the films were $90{\sim}110{\mu}m$. The conductivity properties of prepared PEO electrolytes are summarized as follows. PEO electrolyte complexed with $LiClO_4$ shows the better conductivity of the others. $PEO-LiClO_4$ electrolyte when $EO/Li^+$ ratio is 8, showed the best conductivity. Optimum operating temperature of PEO electrolyte is $60^{\circ}C$. By adding propylene carbonate and ethylene carbonate to $PEO-LiClO_4$ electrolyte, its conductivity was higher than $PEO-LiClO_4$ without those. Also $PEO_8LiClO_4$ electrolyte remains static up to 4.5V vs. $Li/Li^+$.

• 한국세라믹학회지
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• 제33권9호
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• pp.1057-1063
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• 1996

Y2O3-CeO2-ZrO2 powders were prepared from water-soluble salts using a coprecipitation method. The forming process of oxide and the characteristics of the calcined powders treated in different drying conditions were investigated. The oxidation was occurred at the temperature of around 40$0^{\circ}C$ and the main crystallization of ZrO2 around $600^{\circ}C$. On calcination at $600^{\circ}C$ heating lamp-dried powders consisted of agglomerates of globular morphology with average agglomerate size of 2.27${\mu}{\textrm}{m}$ and specific surface area of 68.3m2/g and spray dried powders contained dense spheric particles with average agglomerate size of 1.35${\mu}{\textrm}{m}$ and specific surface area of 11.0m2/g which exhibited low agglomeration tendency. Removal of the water by a freeze-drying technique produced calcined powders containing flake-like secondary particle structures with wide agglomerate size distri-bution of 0.1-60${\mu}{\textrm}{m}$ and specific surface area of 24.5${\mu}{\textrm}{m}$. The 20 MPa-pressed density (36.8-41.4% T,D) of calcined powders did not nealy depend on drying methods whilst compaction ratio of calcined powders derived from freeze-drying was the highest ( 6.24) among three drying methods. On continuous heating up to 150$0^{\circ}C$ the sinterability of calcined powders derived from heating lamp-drying was superior to those derived from spray-and freeze-drying. The final sintered density of calcined powders was the highest (96% T,D at 150$0^{\circ}C$) in case of heating lamp-drying.

• 한국분말재료학회지
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• 제26권3호
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• pp.237-242
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• 2019

In this study, ultrasonic spray pyrolysis combined with salt-assisted decomposition, a process that adds sodium nitrate ($NaNO_3$) into a titanium precursor solution, is used to synthesize nanosized titanium dioxide ($TiO_2$) particles. The added $NaNO_3$ prevents the agglomeration of the primary nanoparticles in the pyrolysis process. The nanoparticles are obtained after a washing process, removing $NaNO_3$ and NaF from the secondary particles, which consist of the salts and $TiO_2$ nanoparticles. The effects of pyrolysis temperature on the size, crystallographic characteristics, and bandgap energy of the synthesized nanoparticles are systematically investigated. The synthesized $TiO_2$ nanoparticles have a size of approximately 2-10 nm a bandgap energy of 3.1-3.25 eV, depending on the synthetic temperature. These differences in properties affect the photocatalytic activities of the synthesized $TiO_2$ nanoparticles.

• 한국분말재료학회지
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• 제28권6호
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• pp.497-501
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• 2021

Cobalt (Co) is mainly used to prepare cathode materials for lithium-ion batteries (LIBs) and binder metals for WC-Co hard metals. Developing an effective method for recovering Co from WC-Co waste sludge is of immense significance. In this study, Co is extracted from waste cemented carbide soft scrap via mechanochemical milling. The leaching ratio of Co reaches approximately 93%, and the leached solution, from which impurities except nickel are removed by pH titration, exhibits a purity of approximately 97%. The titrated aqueous Co salts are precipitated using oxalic acid and hydroxide precipitation, and the effects of the precipitating agent (oxalic acid and hydroxide) on the cobalt microstructure are investigated. It is confirmed that the type of Co compound and the crystal growth direction change according to the precipitation method, both of which affect the microstructure of the cobalt powders. This novel mechanochemical process is of significant importance for the recovery of Co from waste WC-Co hard metal. The recycled Co can be applied as a cemented carbide binder or a cathode material for lithium secondary batteries.

• 암석학회지
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• 제28권4호
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• pp.227-236
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• 2019

논산 관촉사 석조미륵보살입상은 중립 내지 조립질의 흑운모 화강섬록암으로 구성되어 있으며 석불의 제작 시기 및 장소에 대해 고문헌에 반야산의 서북쪽에서 제작되어 동쪽으로 이동하였다는 기록이 있어 채석지가 명확하다. 또한 석불과 주변 기반암의 암상, 조직, 전암대자율 및 감마스펙트로미터 비교 결과, 모두 유사한 특성으로 보여 동일한 기원의 암석으로 판단된다. 이 석불에서 관찰되는 표면오염물에 의한 훼손은 환경적인 요인과 보수물질의 노후에 의한 복합적 요인이 발생하는 것이며, 2007년 제거작업 이후에도 점차 증가하는 경향을 보이므로 지속적인 모니터링이 필요할 것으로 판단된다. 조류의 경우 석조문화재의 표면에 생물학적 오염이 발생하는 경우 착생이 가장 빠르게 진행되며, 곰팡이와 공생체를 이루어 이차적으로 지의류의 착생 가능성이 있어 위치 및 분포 범위에 대한 변화 관찰이 요구된다. 또한 노후된 보수물질은 염의 정출에 따른 오염물 발생, 탈락으로 인한 결합력 저하 등으로 이차적인 훼손이 발생할 수 있으므로 적절한 보존관리를 통해 안정성을 확보하는 것이 바람직하다.

• 화훼연구
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• 제18권1호
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• pp.9-14
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• 2010

본 연구는 털깃털이끼(Hypnum plumaeforme Wilson)의 조직배양시 무성아와 배우체 유기에 미치는 IAA와 kinetin의 영향을 조사하기 위하여 실시하였다. 배양재료는 멸균한 배우체의 정단을 Knop 배지(1865)의 다량요소와 Nitsch와 Nitsch배지 (1956)의 미량요소를 첨가한 고체배지에 배양하여 획득하였다. 배양 초기에는 배양한 배우체의 정단으로부터 원사체가 형성되었으며, 배양 4주에는 새로운 배우체로 전환되었다. 무균의 배우체를 다져서 IAA와 kinetin을 각 0.01, 0.1, 1, $10{\mu}M$의 농도로 단용첨가한 동일배지에 배양한 결과 배우체로부터 원사체 무성아는 물론 이차 원사체도 형성되었다. 그러나 IAA와 kinetin의 농도에 따라 원사체 형성 및 눈 유기가 달라지는 경향을 보였는데, 낮은농도의 IAA와 kinetin을 첨가하는 경우 무성아 형성과 눈의 유기가 촉진되는 경향을 보였다. 특히 kinetin $0.01{\mu}M$을 첨가한 배지에서 눈과 원사체 형성율이 가장 높았다. 배우체의 형성을 위하여kinetin $0.01{\mu}M$을 첨가한 배지에서 형성된 모든 배양재료를 다시 IAA와 kinetin이 0.01, 0.1, 1, $10{\mu}M$씩 단용첨가된 배지에 계대배양하였다. 계대배양한 후 이차 원사체로부터 원사체와 캘러스가 형성되는 과정을 거쳐, 마침내 배우체가 유기되었다. IAA는 배우체 유기와 생장을 조절하였고, kinetin은 무성아 형성과 배우체 유기에 영향을 미쳤다. 본 연구의 결과 조직배양시 첨가한 생장조절물질은 털깃털이끼의 발달과정 전반에 중대한 영향을 미치는 것을 알 수 있었다.

• Asian Journal of Atmospheric Environment
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• 제6권3호
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• pp.234-243
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• 2012

The wintertime high loading for atmospheric pollutants is certainly expected in the Byunsan Peninsula of Korea because of a great-scale reclamation project having construction of 33 km tidal sea dike impounding an area of over 40,000 ha and long-range transport. The goal of this study is to trace the origin of this wintertime burden for ambient particulate matter (hereafter called "PM") in the Byunsan Peninsula of Korea. The size-segregated (i.e., cutoff size from 0.01 ${\mu}m$ to 4.7 ${\mu}m$) PM sampling was conducted at a ground-based site of Byunsan Peninsula located in the west coast of Korean Peninsula during the height of dike constructing. Data archived in this study are the mass concentrations of ionic, elemental, and carbonic components in size-fractioned PM. The elemental mass of individual submicrometer particles was also analyzed. The sum of 5-source (i.e., elemental carbon, organic materials, inorganic secondary pollutants, crustal matter, and sea-salts) concentrations shows the bimodal distribution (major and minor peaks formed around $D_p$, 0.65 ${\mu}m$ and $D_p$, 4.7 ${\mu}m$, respectively) by border with 0.19 ${\mu}m$ of cutoff size. The concentrations of EC in $PM_{1.1-0.01}$ in winter and spring times were 4.62 ${\mu}g\;m^{-3}$ and 3.74 ${\mu}g\;m^{-3}$, respectively. Elemental masses of submicron individual particles are classified into two groups, i.e., the major elements (Cl, Al, Si, S, and P) and the minor trace elements. Cluster analysis differentiated the elements in submicron individual particles into 4-cluster. Among them, three clusters are in agreement with the major (Al, Si, S, and P), minor (Fe, Ca, and K), and trace compositions of coal burning. Meanwhile, Cl classified as an independent cluster has different source profile which was mainly due to the Saemangeum seawall project. Some highly toxic elements (e.g., Cr, Mn, and As (and/or Pb)) were also detected in some part of submicron individual PM. As a consequence, the combination of the Saemangeum project and winter monsoon played a considerable part in the double aggravation of wintertime air pollution in the Byunsan Peninsular.