• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.189-198
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• 1994

The adsorptive behaviors of carbon monoxide and methanol over $V_2O_5$catalyst were studied by means of thermal desorptlon spectroscopy (TDS) under ultrahigh vacuum conditions. Carbon monoxide adsorbed on oxygen-deficient V sites as well as on V=O groups of the $V_2O_5$ surface. CO adsorbed on the V sites desorbed at 380 K while CO adsorbed on the V=O groups formed carbonate species with surface oxygen of $V_2O_5$ and desorbed as $CO_2$ resulting in the reduction of the surface of she $V_2O_5$catalyst. The amount of CO adsorbed in the form of carbonate species increased by both the pre- and post-adsorbed oxygen. The adsorptive behavior of methanol over the catalyst was studied by thermal desorption experiments of $CH_3OH$, HCHO, CO, and $H_2$ upon methanol adsorption at 298 K. The results showed that methanol was adsorbed dissociatively on the $V_2O_5$catalyst as methoxy and hydroxyl groups at 298K.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 1993.04a
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• pp.1-23
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• 1993

중유회는 중유 화력발전소 보일러의 전지집진기에서 생성되는 분진으로 지금까지는 산업폐기물로 폐기되어 왔으나 이의 절대량이 증가하고 환경규제가 엄격하여짐에 따라 그대로 폐기할 수는 없게 되었다. 한편 이중에는 바나듐과 니켈 등의 유가금속이 3-10% 함유되어 있어 자원으로서의 가치가 충분하다. 이에 본 연구에서는 중유회로부터 바나듐과 니켈을 효과적으로 추출, 분리하여 재활용하기 위한 목적으로 바나듐과 오산화바나듐으로 니켈을 황산니켈로 각각 회수하는 방법에 관한 기초연구를 행하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.04a
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• pp.54-55
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• 1995

무기막은 고분자막에 비해서 고온에서의 사용이 가능하고 구조적 안정성 등이 우수한 특징이 있다. 이러한 무기막에 촉매를 담지하거나 코팅하여 분리막의 역할과 촉매로서의 역할을 동시에 수행하는 막반응기로의 응용이 가능하다. 본 연구에서는 Redox mechanism에 의한 부분산화반응을 일으키는 촉매인 오산화바나듐을 sol-gel법으로 코팅한 무기막을 제조하여, 막내부에 오산화바나듐의 격자산소를 이용하는 부분산화 반응물이 존재할 때 선택적으로 증가하는 산소의 투과특성을 조사하였다.

• Analytical Science and Technology
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• v.23 no.6
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• pp.511-517
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• 2010

Dissolution procedure of vanadium pentoxide, which is widely used as a catalyst for production of sulfuric acid or an oxide reaction of the numerous organic compounds, was investigated. Reagent of vanadium pentoxide was completely dissolved in aqua regia-$H_2O_2$-HF solution, but plate type of vanadium pentoxide sample was not clearly dissolved with mixed acids. Thus, in order to establish the dissolution procedure for plate type of vanadium pentoxide, the solubility of vanadium pentoxide was investigated through comparison of acid treatment-fusion and microwave digestion methods. The optimized acid for dissolution of vanadium compound was found to be mixing acids of aqua regia, $H_2O_2$ and HF. Acid-fusion and microwave digestion methods have a similar property in the solubility of vanadium compound, but the latter was more quick and convenient procedure. The content of vanadium pentoxide was found to be $97.9{\pm}0.9%$ using an inductively coupled plasma atomic emission spectrometer after dissolution of a sample with the microwave digestion system.

• Resources Recycling
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• v.26 no.5
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• pp.61-66
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• 2017

Vanadium Dioxide has been investigated for use as a "spectrally-selective" window coating to block infrared transmission and reduce the loss of building interior heat through windows. The preparation of thermochromic $VO_2$ powder by the reductive reaction with hydrogen was studied. The reductive reaction method has many advantages of easy and mass production of $VO_2$ powder according to controlled reaction without semi-conductor equipments like sputter and beam evaporator. The reaction temperature, time, concentration of reductive gas, post-annealing condition and W addition as dopant would affect the characterization of $VO_2$ powder and its thermochromism. Many applications for electrical device and energy-saving technologies is expected.

• Resources Recycling
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• v.31 no.2
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• pp.20-32
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• 2022

This study implemented a chelating agent (Ethylenediaminetetraacetic acid, EDTA) in purification to obtain high-purity vanadium pentoxide (V₂O₅) for use in VRFB (Vanadium Redox Flow Battery). V₂O₅ (powder) was produced through the precipitation recovery of ammonium metavanadate (NH₄VO₃) from a vanadium solution, which was prepared using a low-purity vanadium raw material. The initial purity of the powder was estimated to be 99.7%. However, the use of a chelating agent improved its purity up to 99.9% or higher. It was conjectured that the added chelating agent reacted with the impurity ions to form a complex, stabilizing them. This improved the selectivity for vanadium in the recovery process. However, the prepared V₂O₅ powder exhibited higher contents of K, Mn, Fe, Na, and Al than those in the standard counterparts, thus necessitating additional research on its impurity separation. Furthermore, the vanadium electrolyte was prepared using the high-purity V₂O₅ powder in a newly developed direct electrolytic process. Its analytical properties were compared with those of commercial electrolytes. Owing to the high concentration of the K, Ca, Na, Al, Mg, and Si impurities in the produced vanadium electrolyte, the purity was analyzed to be 99.97%, lower than those (99.98%) of its commercial counterparts. Thus, further research on optimizing the high-purity V₂O₅ powder and electrolyte manufacturing processes may yield a process capable of commercialization.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.491-495
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• 2005

Vanadium pentoxide xerogels with a doping ratio of $Al/V_2O_5$ ranging from 0.01 to 0.05 were synthesized by doping Al into $V_2O_5$ xerogel via the sol-gel process. By using the synthesized $Al_xV_2O_5$, the $Li/Al_xV_2O_5$ cells were assembled to investigate the chemical and electrochemical properties. Surface morphology of the $Al_xV_2O_5$ xerogel showed an anisotropic corrugated sheet-like matrix, and the interlayer distance was about $11.5{\AA}$. The IR spectra of the $Al_xV_2O_5$ revealed that the doped Al was coordinated to the vanadyl group in $V_2O_5$. The $Al_xV_2O_5$ xerogels showed enhanced reversibility and energy density compared with the $V_2O_5$ xerogel. The specific capacity of the $Al_{0.05}V_2O_5$ xerogel was more than 200 mAh/g at 10 mA/g discharge rate, and cycle efficiency was about 90% after the 31st cycling test between 1.9 V and 3.9 V.

• Resources Recycling
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• v.31 no.2
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• pp.40-48
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• 2022

In this study, the effects of solution components were investigated in the recovery of vanadium as ammonium metavanadate from vanadium-ore-salt roasting-water leaching solution. The vanadium-containing solution is strongly alkaline (pH 13), so the pH must be lowered to 9 or less to increase the ammonium metavanadate precipitation efficiency. However, in the process of adjusting the solution pH using sulfuric acid, aluminum ions are co-precipitated, which must be removed first. In this study, aluminum was precipitated in the form of an aluminum-silicate compound using sodium silicate, and the conditions for minimizing vanadium loss in this process were investigated. After aluminum removal, the silicate was precipitated and removed by adjusting the solution pH to 9 or less using sulfuric acid. In this process, the concentration and addition rate of sulfuric acid have a significant influence on the loss of vanadium, and vanadium loss was minimized as much as possible by slowly adding dilute sulfuric acid. Ammonium metavanadate was precipitated using three equivalents of ammonium chloride at room temperature from the aluminum-free, aqueous solution of vanadium following the pH adjustment process. The recovery yield of vanadium in the form of ammonium metavanadate exceeded 81%. After washing the product, vanadium pentoxide with 98.6% purity was obtained following heat treatment at 550 ℃ for 2 hours.

• Particle and aerosol research
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• v.16 no.4
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• pp.95-105
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• 2020

Vanadium Pentoxide (V2O5) has been emerged as alternative electrode materials for supercapacitors due to their low cost, natural abundance, and environmental friendliness. Graphene (GR) loaded with V2O5 can exhibit enhanced specific capacitance. In this study, we present three-dimensional (3D) crumpled graphene (CGR) decorated with V2O5. The V2O5-graphene composites were synthesized from a colloidal mixture of graphene oxide (GO) and Ammonium metavanadate (NH4VO3), via aerosol spray drying and post heat treatment process. The average size of composite was ranged from 1.82 to 4.6 ㎛. Morphology of the composite changed from a crumpled paper ball to spherical ball having relatively smooth surface as the content of V2O5 increased in the composites. The electrochemical performance of the V2O5-graphene composites was examined. The V2O5-graphene composite electrode showed the specific capacitance of 312 F/g. In addition, the device possessed acceptable cyclic stability, with 84% after 2000 cycles at 2 A/g. These outstanding properties are expected to make the composites prepared in this study as promising electrode materials for supercapacitor applications.