• Korean Chemical Engineering Research
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• 제46권2호
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• pp.397-401
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• 2008

레이저 애블레이션에 의해서 가지상 구조체 형상인 나노입자 응집체를 합성하였다. 기존 마이크론 금속섬유 필터의 표면상에 나노입자 응집체를 고착하여 여과성능을 향상시켰다. 에어로졸 상에서 소결 처리된 나노입자 응집체를 증착한 후 열처리를 하여 나노구조체가 표면상에 형성된 소결 처리된 나노입자 응집체 고착 필터를 제작하였다. 소결 온도가 증가할수록 마이크론 금속섬유 필터 표면상에 고착된 나노입자 응집체의 표면적 증가로 인하여 차압은 조금 증가하지만 여과효율은 현저하게 증가하였다.

• Carbon letters
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• 제28권
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• pp.47-54
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• 2018

High surface carbon aerogels with hierarchical and tunable pore structure were prepared using ionic liquid as carbon precursor via a simple salt templating method. The as-prepared carbon aerogels were characterized by nitrogen sorption measurement and scanning electron microscopy. Through instant visual observation experiments, it was found that salt eutectics not only serve as solvents, porogens, and templates, but also play an important role of foaming agents in the preparation of carbon aerogels. When the pyrolyzing temperature rises from 800 to $1000^{\circ}C$, the higher temperature deepens the carbonization reaction further to form a nanoporous interconnected fractal structure and increase the contribution of super-micropores and small mesopores and improve the specific surface area and pore volume, while having few effects on the macropores. As the mass ratio of ionic liquid to salt eutectics drops from 55% to 15%, that is, the content of salt eutectics increases, the salt eutectics gradually aggregate from ion pairs, to clusters with minimal free energy, and finally to a continuous salt phase, leading to the formation of micropores, uniform mesopores, and macropores, respectively; these processes cause BET specific surface area initially to increase but subsequently to decrease. With the mass ratio of ionic liquids to salts at 35% and carbonization temperature at $900^{\circ}C$, the specific surface area of the resultant carbon aerogels reached $2309m^2g^{-1}$. By controlling the carbonization temperature and mass ratio of the raw materials, the hierarchically porous architecture of carbon aerogels can be tuned; this advantage will promote their use in the fields of electrodes and adsorption.

• Journal of Electrochemical Science and Technology
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• 제12권4호
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• pp.458-464
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• 2021

Lithium ion batteries (LIBs) is a kind of rechargeable secondary battery, developed from lithium battery, lithium ions move between the positive and negative electrodes to realize the charging and discharging of external circuits. Zeolitic imidazolate frameworks (ZIFs) are porous crystalline materials in which organic imidazole esters are cross-linked to transition metals to form a framework structure. In this article, ZIF-67 is used as a sacrificial template to prepare nano porous carbon (NPC) coated cobalt nanoparticles. The final product Co/NPC composites with complete structure, regular morphology and uniform size were obtained by this method. The conductive network of cobalt and nitrogen doped carbon can shorten the lithium ion transport path and present high conductivity. In addition, amorphous carbon has more pores that can be fully in contact with the electrolyte during charging and discharging. At the same time, it also reduces the volume expansion during the cycle and slows down the rate of capacity attenuation caused by structure collapse. Co/NPC composites first discharge specific capacity up to 3115 mA h/g, under the current density of 200 mA/g, circular 200 reversible capacity as high as 751.1 mA h/g, and the excellent rate and resistance performance. The experimental results show that the Co/NPC composite material improves the electrical conductivity and electrochemical properties of the electrode. The cobalt based ZIF-67 as the precursor has opened the way for the design of highly performance electrodes for energy storage and electrochemical catalysis.

• 한국물환경학회지
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• 제30권3호
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• pp.292-297
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• 2014

We synthesized the self-organized nanoporous oxide with potentiostatic anodization of iron foil. The iron oxide nanocomposite (INCs) were fabricated in 1M $Na_2SO_4$ containing 0.5wt% NaF electrolyte holding the potential at 20, 40 and 60 V for 20min, respectively. Field Emmision Scanning Electron Microscopy (FESEM) and X-ray Diffractometer (XRD) were used to evaluate the micromorphology and crystalline structure of INC film. Also, this study was performed to evaluate the fenton reaction using INC film with hydroperoxide for degradation of cyanide dissolved in water. In case of INC-40V in the presence of $H_2O_2$ 3%, the first-order rate constant was found to be $1.7{\times}10^{-2}min^{-1}$, and indicated to be $1.2{\times}10^{-2}min^{-1}$ on commercial hematite powder. This result is shown to be good performance enough to replace the powder type for treatment of wastewater.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1100-1101
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• 2015

In this work, the effect of addition of acetylacetone on microstructure and quality of nanoporous $TiO_2$ photo-electrodes was studied in dye-sensitized solar cells (DSCs) and structure and electrical properties of fabricated cells were investigated. From the results, the DSCs fabricated with acetyl acetone showed highest photovoltaic performances. This behavior may be attributed to paste agglomeration decrease and interconnection and bonding improvement between $TiO_2$ particles. Furthermore, the most favorable dye absorption time results to be 10h: exceeding this time a decrease in efficiency is observed despite the increasing amount of dye absorption. The $TiO_2$ photo-electrode prepared under the conditions of acetylacetone ratio of 15% and dye absorption time of 10hr showed the better photovoltaic performance ($J_{sc}=12.48mA/cm^2$, $V_{oc}=0.69V$, ff=0.68, ${\eta}=5.86%$).

• 청정기술
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• 제13권1호
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• pp.64-71
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• 2007

천연가스로부터 유기 황 화합물인 THT와 TBM의 제거를 위한 적합한 흡착제의 선정이 수행되었다. 황 화합물에 대한 포화 흡착량은 Na-Y, Na-ZSM-5, Na,K-ET(A)S-10, Na-모더나이트, Na,K-클리놉틸올라이트, Ti/MCM-41, Ti/SBA-15이 포함되어진 나노세공 물질 및 무정형 티타노실리케이트에 대하여 펄스 흡착 방법에 의해 측정되었다. 측정되어진 물질들 중 Na-Y 와 Na,K-ET(A)S-10 제올라이트에서 THT와 TBM에 높은 흡착 용량을 보였다. Na,K-ET(A)S-10에서의 THT에 대한 포화 흡착량은 효율적인 흡착제로 잘 알려진 Na-Y 제올라이트와 비슷하였다. Na,K-ET(A)S-10에서의 THT와 TBM의 흡착량과 흡착능은 Na,K-ET(A)S-10의 결정성이 좋을수록 증가하였다. 모사되어진 천연가스를 이용한 파과 평가로부터 THT와 TBM 사이의 경쟁적 흡착에 관한 연구에서 Na,K-ET(A)S-10은 THT에 선택적으로 흡착하는 것으로 나타났다. Na,K-ET(A)S-10의 THT에 대한 파과 용량은 1.19 mmol/g 이었다. 이러한 결과들은 Na,K-ETS-10과 Na,K-ETAS-10의 높은 흡착 성능이 제올라이트 구조의 넓은 기공 성질과 유기 황 화합물과의 강한 정전기적 상호작용을 지닌 제올라이트 구조 속의 높게 교환되어진 양이온에 기인하는 것으로 보인진다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.155-155
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• 2017

Surface modifications are commonly utilized to adjust the properties of the titanium and its alloy surface to the specific needs of the medical applications, but there are disadvantages such as poor osteoconductive properties and low adhesion of bone cell to implant surface. In order to improve these disadvantages, changes in surface properties have an important effect on osseointegration during implantation. In this paper we applied new technological method for improving a unique surface modification using the characteristic of an electrolytic Solution. Thus, in the electrolyte containing NaF in Na2SO4, TiO2 nanoporous was uniformly formed, and HAp nanoparticles were electrodeposited around the TiO2 nanopores, but in the electrolyte containing NH4F in (NH4)H2PO4, the coarse protrusions including HAp nano particles were regularly deposited onto the TiO2 barrier layer. The surface characteristics and the distributed elements and have been investigated by EDS analysis, and ultra-fine structure of surface are carried out using FE-SEM. To investigate the behavior of the anion, the analysis of chemical states was performed by XPS, and the narrow spectrums for Ti2P, Ca 2p, and P 2p seems to be almost similar depending on the characteristics of the electrolyte solution respectively. In addition, Ca 2p spectrum could be resolved into two peaks for Ca 2p3/2 and 2p1/2 at 347.4 and 351.3 eV, which are related to hydroxyapatite. And, the P peak can also be deconvoluted into two peaks for P1/2 and P3/2 levels with binding energy 134.2 and 133.4 eV, respectively. From the result of soaking test, the apatite morphologys were well-formed onto the modified surface according to the different conditions.

• 한국표면공학회지
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• 제49권3호
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• pp.280-285
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• 2016

In this study, we investigated the influences of potassium fluoride(KF) addition on the surface characteristics of plasma electrolytic oxidation(PEO) coating produced on Al alloy. The PEO of marine grade Al alloy(5083 grade) was conducted in KOH 1g/L solution adding different concentrations of KF(0, 1 and 2 g/L) under a galvanostatic regime. With KF addition, unusual behavior was observed on the voltage-time characteristic curves, which can be characterized by the following process: (i) initial rapid increase in voltage (ii) a short plateau after 1st breakdown (iii) gradual increase in voltage (iv) intermittent fluctuation of voltage after 2nd breakdown. The SEM observation revealed irregular surface morphology with KF addition, as compared with one formed without KF addition, which had a reticulate structure. The XRD analysis detected the formation of aluminium hydroxide fluoride hydrate($H_{4.76}Al_2F_{3.24}O_{3.76}$) on surface grown by PEO process with KF. Particularly, at very early stage of the process (~ 120 s), thin film was formed having nanoporous structure, and F element was confirmed on surface by EDS analysis. The thickness and surface roughness of the coating increased with increasing KF concentration. As a result, KF addition was found to be less beneficial influences on PEO of marine grade Al alloy, and therefore needs further research to improve its capability.

• 한국결정성장학회지
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• 제29권2호
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• pp.77-81
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• 2019

최근 환경오염에 관한 문제가 대두됨에 따라서 친환경 수처리 공법에 관한 다양한 방법들이 논의되고 있다. 현재 시장을 주도하고 있는 고분자 멤브레인은 저가이나, 내화학성 및 내구성 측면에서 많은 문제점을 안고 있다. 이에 따라 친환경적이며 내구성, 내화학성이 뛰어난 세라믹 멤브레인의 기공 구조, 크기 및 표면 처리를 통하여 고효율의 수처리용 세라믹 멤브레인을 제작하였다. $ZrO_2$ 및 $TiO_2$의 균일한 코팅막 형성을 통하여 멤브레인의 기공 크기를 조절 하였다. 테입케스팅, 졸겔 공정법을 활용하여 멤브레인 표면에 성공적으로 나노기공을 가지는 세라믹 코팅막을 형성하였다. 세라믹 멤브레인의 미세조직 분석, 코팅막의 기공의 크기 분석을 진행하였으며 이에 대한 수처리 특성 변화를 관측하였다.

• 한국환경과학회지
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• 제23권5호
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• pp.943-962
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• 2014

Industrial gas drying, dilute gas mixtures purification, air fractionation, hydrogen production from steam reformers and petroleum refinery off-gases, etc are conducted by using adsorptive separation technology. The pressure swing adsorption (PSA) has certain advantages over the other methods, such as absorption and membrane, that are a low energy requirement and cost-effectiveness. A key component of PSA systems is adsorbents that should be highly selective to a gas being separated from its mixture streams and have isotherms suitable for the operation principle. The six standard types of isotherms have been examined in this review, and among them the best behavior in the adsorption of $CO_2$ as a function of pressure was proposed in aspects of maximizing a working capacity upon excursion between adsorption and desorption cycles. Zeolites and molecular sieves are historically typical adsorbents for such PSA applications in gas and related industries, and their physicochemical features, e.g., framework, channel structure, pore size, Si-to-Al ratio (SAR), and specific surface area, are strongly associated with the extent of $CO_2$ adsorption at given conditions and those points have been extensively described with literature data. A great body of data of $CO_2$ adsorption on the nanoporous zeolitic materials have been collected according to pressure ranges adsorbed, and these isotherms have been discussed to get an insight into a better $CO_2$ adsorbent for PSA processes.