• 멤브레인
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• 제17권1호
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• pp.44-53
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• 2007

본 연구에서는 나노여과막과 역삼투막의 표면 개질을 통하여 유량의 향상 및 내오염성을 향상시키는 제조 방법을 개발하였다. 실란 화합물이 코팅된 복합막의 표면 성질이 막 오염 지수 MFI 값에 미치는 영향을 살펴보았다. 상용화된 역삼투막(RE1812-LP)과 나노여과막(ESNA 4040-LF) 복합막을 기저막으로 사용하여 실란 커플링제의 농도를 달리하여 개질 복합막을 제조하였다. 실란 커플링제 aminopropylmethoxydiethoxysilane은 아민 관능기와 3개의 알콕시 관능기를 가지며 아민 관능기가 가지는 친수성 특성이 개질막의 투과 수량 및 내오염성에 미치는 영향을 조사하였다. 개질막의 실란층의 안정적인 형성을 확인하기 위하여 FE-SEM, 접촉각 측정 및 제타 전위값 등의 표면 특성 변화를 살펴보았다. 특히 개질된 나노여과막의 2가 이온 수용액을 공급수로 할 경우 염제거율에 대한 영향 없이 내오염성이 현저히 증가함을 확인하였다.

• 한국재료학회지
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• 제18권9호
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• pp.457-462
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• 2008

Through the electrostatic interaction between the poly-diallydimethylammonium chloride (PDDA) modified Multi-walled carbon nanotube (MWNT) and $SnO_2$ suspension in 1mM $NaNo_3$ solution, MWNT-$SnO_2$ nanocomposites (MSC) for anode electrodes of a Li-ion battery were successfully fabricated by colloidal heterocoagulation method. TEM observation showed that most of the $SnO_2$ nanoparticles were uniformly deposited on the outside surface of the MWNT. Galvanostatic charge/discharge cycling tests showed that MSC anodes exhibited higher specific capacities than bare MWNT and better cyclability than unsupported nano-$SnO_2$ anodes. Also, after 20 cycles, the MSC anode fabricated by heterocoagulation method showed more stable cycle properties than the simply mixed MSC anode. These improved electrochemical properties are attributed to the MWNT, which adsorbs the mechanical stress induced from volume change and increasing electrical conductivity of the MSC anode, and suppresses the aggregation between the $SnO_2$ nanoparticles.

• Advances in nano research
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• 제5권3호
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• pp.215-230
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• 2017

The development of hybrid systems comprising nanoparticles and polymers is an opening pathway for engineering nanocomposites exhibiting outstanding mechanical, optical, electrical, and magnetic properties. Among inorganic counterpart, iron oxide nanoparticles (IONP) exhibit high magnetization, controllable surface chemistry, spintronic properties, and biological compatibility. These characteristics enable them as a platform for biomedical applications and building blocks for bottom-up approaches, such as the layer-by-layer (LbL). In this regard, the present study is addressed to investigate IONP synthesised through co-precipitation route (average diameter around 7 nm), with either positive or negative surface charges, LbL assembled with sodium sulfonated polystyrene (PSS) or polyaniline (PANI). The surface and internal morphologies, and electrochemical properties of these nanocomposites were probed with atomic force microscopy, UV-vis and Raman spectroscopy, scanning electron microscopy, cross-sectional transmission electron microscopy, and electrochemical measurements. The nanocomposites display a globular morphology with IONP densely packed while surface dressed by polyelectrolytes. The investigation of the effect of thermal annealing (300 up to $600^{\circ}C$) on the oxidation process of IONP assembled with PSS was performed using Raman spectroscopy. Our findings showed that PSS protects IONP from oxidation/phase transformation to hematite up to $400^{\circ}C$. The electrochemical performance of nanocomposite comprising IONP and PANI were investigated in $0.5mol{\times}L^{-1}$ $Na_2SO_4$ electrolyte solution by cyclic voltammetry and chronopotentiometry. Our findings indicate this structure as promising candidate for potential application as electrodes for supercapacitors.

• Asian Pacific Journal of Cancer Prevention
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• 제15권3호
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• pp.1299-1306
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• 2014

Background: Nano-biotechnology is recognized as offering revolutionary changes in various fields of medicine. Biologically synthesized silver nanoparticles have a wide range of applications. Materials and Methods: Silver nanoparticles (AgNPs) were biosynthesized with an aqueous extract of Pterocladiella (Pterocladia) capillacea, used as a reducing and stabilizing agent, and characterized using UV-VIS spectroscopy, Fourier Transform Infra red (FT-IR) spectroscopy, transmission electron microscopy (TEM) and energy dispersive analysis (EDX). The biosynthesized AgNPs were tested for cytotoxic activity in a human hepatocellular carcinoma ($HepG_2$) cell line cultured in Dulbecco's modified Eagle medium supplemented with 10% fetal bovine serum, 1% antibiotic and antimycotic solution and 2 mM glutamine. Bacterial susceptibility to AgNPs was assessed with Staphylococcus aureus, Bacillus subtilis [Gram+ve] and Pseudomonas aeruginosa and Escherichia coli [Gram-ve]. The agar well diffusion technique was adopted to evaluate the bactericidal activity of the biosynthesized AgNPs using Ampicillin and Gentamicin as gram+ve and gram-ve antibacterial standard drugs, respectively. Results: The biosynthesized AgNPs were $11.4{\pm}3.52$ nm in diameter. FT-IR analysis showed that carbonyl groups from the amino acid residues and proteins could assist in formation and stabilization of AgNPs. The AgNPs showed potent cytotoxic activity against the human hepatocellular carcinoma ($HepG_2$) cell line at higher concentrations. The results also showed that the biosynthesized AgNPs inhibited the entire panel of tested bacteria with a marked specificity towards Bacillus subtillus. Conclusions: Cytotoxic activity of the biosynthesized AgNPs may be due to the presence of alkaloids present in the algal extract. Our AgNPs appear more bactericidal against gram-positive bacteria (B. subtillus).

• 한국분말재료학회지
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• 제21권5호
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• pp.377-381
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• 2014

This work describes the coloration, chemical stability of $SiO_2$ and $SnO_2$-coated blue $CoAl_2O_4$ pigment. The $CoAl_2O_4$, raw materials, were synthesized by a co-precipitation method and coated with silica ($SiO_2$) and tin oxide ($SnO_2$) using sol-gel method, respectively. To study phase and coloration of $CoAl_2O_4$, we prepared nano sized $CoAl_2O_4$ pigments which were coated $SiO_2$ and $SnO_2$ using tetraethylorthosilicate, $Na_2SiO_3$ and $Na_2SiO_3$ as a coating material. To determine the stability of the coated samples and their colloidal solutions under acidic and basic conditions, colloidal nanoparticle solutions with various pH values were prepared and monitored over time. Blue $CoAl_2O_4$ solutions were tuned yellow color under all acidic/basic conditions. On the other hand, the chemical stability of $SiO_2$ and $SnO_2$-coated $CoAl_2O_4$ solution were improved when all samples pH values, respectively. Phase stability under acidic/basic condition of the core-shell type $CoAl_2O_4$ powders were characterized by transmission electron microscope, X-ray diffraction, CIE $L^*a^*b^*$ color parameter measurements.

• 한국응용과학기술학회지
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• 제29권2호
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• pp.311-316
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• 2012

우리는 순환전압전류법에 의한 LB 필름에 대한 전기화학적 특성을 조사하였다. 인지질 화합물은 ITO glass에 Langmuir-Blodgett법을 사용하여 제막하였다. 0.5, 1.0, 1.5 및 2.0 N $NaClO_4$ 용액에서 3 전극 시스템 (Ag/AgCl 기준전극, 백금선 카운터 전극 및 LB 필름이 코팅된 ITO 작업전극)으로 순환전압전류법을 사용하여 전기화학적 측정을 시도하였다. 측정 범위는 연속적으로 1650 mV로 산화시키고, 초기전위인 -1350 mV로 환원시켰다. 그 결과, 인지질 화합물의 LB 필름은 순환전압전류도표로부터 오직 산화전류로 인한 비가역공정으로 나타났다. LB 필름의 확산계수(D) 효과는 인지질 화합물 양의 증가로 인하여 감소하였다.

• Corrosion Science and Technology
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• 제16권5호
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• pp.257-264
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• 2017

Film of new Ti-15Zr-5Nb alloy formed during galvanic anodizing in orthophosphoric acid solution was characterized by optical microscope, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and Raman micro-spectroscopy. Its anticorrosive properties were determined by electrochemical techniques. The film had a layer with nanotube-like porosity with diameters in 500-1000 nm range. The nano layer contained significant amounts of P and O as well as alloying element. Additionally, Raman micro-spectroscopy identified oxygen as oxygen ion in $TiO_2$ anatase and phosphorous as $P_2O_7{^{4-}}$ ion in phosphotitanate compound. All potentiodynamic polarization curves in artificial Carter-Brugirard saliva with pH values (pH= 3.96, 7.84, and 9.11) depending on the addition of 0.05M NaF revealed nobler behavior of anodized alloy and higher polarization resistance indicating the film is thicker and more compact nanolayer. Lower corrosion rates of the anodized alloy reduced toxicity due to less released ions into saliva. Bigger curvature radii in Nyquist plot and higher phase angle in Bode plot for the anodized alloy ascertain a thicker, more protective, insulating nanolayer existing on the anodized alloy. Additionally, ESI results indicate anodized film consists of an inner, compact, barrier, layer and an outer, less protective, porous layer.

• 한국세라믹학회지
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• 제42권3호
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• pp.205-210
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• 2005

Tetraethyl Orthosilicate(TEOS)를 $SiO_2$ 전구체 용액으로 사용하여 Polyacrlamide gel 방법으로 나노 실리카 분말을 합성하였다. 이 gel 공정법은 비교적 간단한 중합법이며, 고분자 망상구조가 $SiO_2$의 응집을 억제하므로 비교적 낮은 하소온도에서 나노입자를 합성할수 있었다. $SiO_2$ 분말입자의 크기는 gel 전구체중의 ammonium persulphate와 N,N'-methylene-bis-acryamide(BIS)의 농도에 영향을 받았다. 실리카 입자의 크기는 ammonium persulphate의 농도가 증가할수록 작아졌으며 그 농도가 0.01M일때 가장 작은 10nm크기의 입자를 얻었다. 또한 그 입자의 크기는 BIS의 농도가 증가할수록 작아졌으며 그 높도가 0.05M일때 입자의 크기는 5nm였다.

• Korean Chemical Engineering Research
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• 제44권5호
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• pp.540-546
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• 2006

파일럿 크기의 흐름반응기에서 유기와 무기 첨가제가 질소산화물의 선택적 무촉매 환원반응에 미치는 영향을 공정변수 변화에 따라 고찰하였다. 질소산화물 저감효율은 반응기의 체류시간과 초기 NOx 농도 증가에 따라 증가하였다. 요소용액에 의한 NOx 환원반응은 $850^{\circ}C$에서 시작되어 $970^{\circ}C$에서는 최대값을 나타내었으며, NSR = 2.0까지 증가 하였다. 유기첨가제로서 에탄올과 페놀의 첨가는 온도창을 저온 영역으로 이동시켰으며, 에탄올 구조내의 탄화수소에 의한 부반응으로 최대의 NOx 저감효율이 감소하였다. NaOH 첨가는 NaOH의 연쇄반응과 $N_2O$ 저감으로 인하여 온도창을 확대시키고, 최대 NOx 저감효율을 10％ 정도 향상시켰다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.21-24
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• 2003

In general, to enhance physical properties of PET-layered silicate nanocomposites $(P_{et}LSNs)$, it has been well known that the organic modifiers should introduce into gallery regions. However, the organic modifiers in$(P_{et}LSNs)$ may result in thermal decomposition by melt processing at high temperature, and it necessarily lead to deteriorate various physical properties of final products. Therefore, in this study, $(P_{et}LSNs)$ excluding and including organic modifiers were prepared by solution method $(S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom})$ and we (focused on the effects of the organic modifiers in $P_{et}$ LSNs with exfoliation structure on the crystallization behaviors, the optical transparency, the thermal stability and the mechanical property. The absence and existence of organic modifiers in $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were investigated by EA and TGA, and nano-structure of silicate layers in $S-P_{et}LSNs$ was evaluated by using WXRD, SAXS and TEM. $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were mixed with neat PET as masterbatches by melt method $(M-P_{et}LSNs_{eom} and M-P_{et}LSNs_{iom})$, and also neat PET was mixed with organically modified layered silicates (OLS) by conventional direct melt method $(D-P_{et}LSNs) at 270^{\circ}C$. As results, it was found that $M-P_{et}LSNs_{eom}, M-P_{et}LSNs_{iom}, and D-P_{et}LSN$ showed a exfoliated structure and exhibited faster crystallization rate, better thermal stability and mechanical property than those of neat PET due to the dispersed and detaminated silicate layers in PET matrix. Whereas, considering organic modifiers effect, $M-P_{et}LSNs_{eom} and D-P_{et}LSN$ exhibited slower crystallization rate, poorer optical, thermal and mechanical properties, in comparison to $M-P_{et}LSNs_{eom}> due to the thermal decomposition of organic modifier in $D-P_{et}LSNs$ during melt method.