• Title/Summary/Keyword: 불소처리

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A Study on PTC/NTC Behavior of Fluorinated Carbon Black-filled HDPE Matrix Compounds (불소처리된 카본블랙을 충전한 HDPE 기지 컴파운드의 PTC/NTC 특성에 관한 연구)

  • Soo-Jin Park;Su-Wan Song;Min-Kang Seo;Jae-Sup Shin;Kyuchul Kim
    • Journal of the Korean Chemical Society
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    • v.47 no.2
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    • pp.147-154
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    • 2003
  • In this study, the fluorinated carbon blacks(CB) were used to reduce the negative temperature coefficient (NTC) phenomenon of the CB-filled high density polyethylene(HDPE) compounds in the fluorination pressure of 0.1-0.4 MPa. The changes in surface properties of the CB were investigated by using FT-IR, XPS and contact angle measurements. From the FT-IR results, the fluorinated CB showed the C-F absorption peak at 1400-1000 cm$^{-1}$ and the peak intensity was increased with increasing the fluorination pressure. Also, the analysis of XPS spectra of the fluorinated CB indicated that fluorine content was increased with increasing the fluorination pressure. Meanwhile, the surface free energy of the fluorinated CB was decreased with increasing the fluorination pressure. Consequently, the increase of fluorine contents on CB made a disappearance of NTC behaviors of CB/HDPE compounds, which was probably due to the reduction of CB reaggregation after melting point of the HDPE, resulting from decreasing the surface free energy of CB particles.

Preparation and Characteristics of Fluorinated Carbon Nanotube Applied Capacitive Desalination Electrode with Low Energy Consumption (불소화 탄소나노튜브를 적용한 저에너지 소모형 축전식 탈염전극의 제조 및 특성)

  • Yoo, Hyun-woo;Kang, Ji-hyun;Park, Nam-soo;Kim, Tae-il;Kim, Min-Il;Lee, Young-Seak
    • Applied Chemistry for Engineering
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    • v.27 no.4
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    • pp.386-390
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    • 2016
  • The surface of carbon nanotubes (CNTs) was modified by fluorination and applied to conductive materials to improve the energy efficiency of a capacitive desalination (CDI) electrode. CNTs were fluorinated at room temperature with a mixed gas of fluorine and nitrogen, and activated carbon based CDI electrodes were then prepared by adding 0-0.5 wt% of untreated CNTs or fluorinated CNTs with respect to the activated carbon. Fluorinated CNTs showed improved dispersibility in the electrode and also slurry as compared to untreated CNTs, which was confirmed by the zeta potential and scanning electron microscopy. Fluorinated CNTs added electrodes showed higher desalination efficiency but lower energy consumption than those of using untreated CNTs added electrodes. This was attributed to the decrease in the resistance of CDI electrodes due to the improved dispersibility of CNTs by fluorination.

Experimental Research on the Surface Changes and the Abrasion Resistance of Pit and Fissure Sealant by Fluoride (불소도포제에 의한 치면열구전색제의 마모저항성과 표면 변화에 관한 실험연구)

  • Hwang, Su-Hyun;Yu, Ji-Su
    • Journal of dental hygiene science
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    • v.10 no.5
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    • pp.373-378
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    • 2010
  • To test the effects of representative fluoride vanishes-1.23% APF gel and 5% NaF Fluoride Varnish-on the surface structure of pit and fissure sealant, this study classified samples of pit and fissure sealant into five groups: Group I deposited in distilled water for ten minutes, Group II treated with APF gel for one minute, Group III treated with APF gel for four minutes, Group IV treated with Fluoride Varnish for one minute, and Group V treated with Fluoride Varnish for four minutes. An abrasion test was carried out to measure changes in weight, along with observation of the surface structure by using an optical microscope, consequently drawing the following conclusions. 1. The results of the abrasion test using pit and fissure sealant, Concise, showed that Group III had the reduction in weight more increased than Group I and that Group V had less reduction in weight (p<0.05); the results of the abrasion test using Eco-S showed Group III had the reduction in weight more increased than Group I and that Group V had less reduction in weight (p<0.05). 2. The results of observation using an optical microscope showed that application of APF gel made the filler remarkable due to loss of substrate and that Group III treated with APF gel for four minutes had the toughest surface, followed by Group II treated with APF gel for one minute, Group I deposited in distilled water for ten minutes, Group IV treated with Fluoride Varnish for one minute, and Group V treated with Fluoride Varnish for four minutes.

Fluoride Migration of Frozen Antarctic Krill According to Thawing Methods (해동방법에 의한 냉동크릴의 불소이동)

  • Kim, Kil-Hwan;Kim, Dong-Man;Kim, Young-Ho;Yoon, Hye-Hyun
    • Korean Journal of Food Science and Technology
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    • v.22 no.2
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    • pp.168-171
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    • 1990
  • This study was purposed to elucidate the migration phenomenon of fluoride from the chitinous sections into the muscle flesh of the frozen krill during thawing. The fluoride content ratio between chitinous sections and muscle flesh in the frozen krill was 94.8 : 5.2. Among the several thawing methods used, migration velocity of fluoride was the highest in the krill thawed with microwave and the lowest in the krill thawed at low temperature $(4^{\circ}C)$. The migrated amount of fluoride after thawing was various depended upon the thawing methods, and the increased amount during thawing was 2-5 times higher than Initial amount before thawing.

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Effects of the Fluorination of Activated Carbons on the Chromium Ion Adsorption (활성탄소의 불소화가 크롬이온 흡착에 미치는 영향)

  • Kim, Min-Ji;Jung, Min-Jung;Choi, Suk Soon;Lee, Young-Seak
    • Applied Chemistry for Engineering
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    • v.26 no.1
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    • pp.92-98
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    • 2015
  • In this study, phenol-based activated carbons (ACs) were fluorinated at various fluorine partial pressures (0.01~0.03 MPa) and the $Cr^{6+}$ ion adsorption of fluorinated ACs was investigated. According to BET and XPS results, the specific surface area and total pore volume of fluorinated ACs increased by 24.7 and 55.8%, respectively, and fluorine functional groups were introduced to AC surface. The most optimized condition of $Cr^{6+}$ ion adsorption was confirmed at the fluorine partial pressure of 0.02 MPa. And also the removal efficiency of $Cr^{6+}$ ion was up to 98% at 300 mg/L of the initial concentration, and these results showed an approximately three-fold increase compared to that of using untreated ACs. Furthermore, the $Cr^{6+}$ ion adsorption of fluorinated ACs was completed in less than 30 min in contrast with untreated ACs, which was expected to be an increase of the affinity between $Cr^{6+}$ ions and ACs surfaces by fluorination.

THE EFFECTS OF SODIUM FLUORIDE ON SQUAMOUS CELL CARCINOMA CELL LINE CULTURED IN VITRO (실험실 내에서 배양된 편평상피암 세포주에 대한 염화불소의 효과)

  • Park, No-Boo
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.18 no.2
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    • pp.316-322
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    • 1996
  • The effects of Sodium Fluoride on squamous cell carcinoma cell line(SCC-cells) cultured in vitro have been studied with respect to cytotoxicity and induction of chromosome aberrations. Cytotoxicity of NaF on SCC-cells, as determined by a decrease in colony-forming ability, linearly increased with dose of NaF(150-300 ug/ml) or exposure time (3-24h). SCC-cells treated with 30-60ug/ml NaF for 24h were analyzed for chromosome aberrations. A significant increase in the frequency of chromosome aberration at the chromatid level was induced by NaF in a dose-dependent manner. These results suggest that NaF is a toxic substance which inhibit cell proliferation and causes DNA damage in SCC-cells cultured in Vitro.

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Physical-Chemical Properties of Graphite Foams Produced with Fluorinated Mesophase Pitch (불소화 메조페이스 핏치로 제조된 그라파이트 폼의 물리/화학적 특성)

  • Kim, Ji-Hyun;Kim, Do Young;Lee, Hyung-Ik;Lee, Young-Seak
    • Korean Chemical Engineering Research
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    • v.54 no.6
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    • pp.830-837
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    • 2016
  • In order to improve the compressive strength of graphite foams (GFms), mesophase pitch (MP) was stabilized in air atmosphere and then fluorinated at different conditions. The Fluorine/Carbon (F/C) in surface-chemical contents of fluorinated MP has range of 23.75%~61.48% according to the different fluorine partial pressure. The compressive strengths of GFms prepared from fluorinated MP were increased in proportion to the apparent densities. The compressive strength of the GFm produced from MP with 35.93% of F/C (%) showed maximum value in $2.93{\pm}0.06MPa$, which was increased up to 27.95% than that of the GFm prepared from un-fluorinated MP. This result was attributed that the interface bonding between of MPs due to fluorine functional groups with high surface energy helped to improve compressive strength of the GFm.

Treatment Features of Fluorine-containing Wastewater Using Calcium as a Precipitant for Its Reuse (처리수(處理水) 재사용(再使用)을 위한 칼슘 침전법(沈澱法)에 의한 불소폐수(弗素廢水) 처리(處理) 특성(特性))

  • Kim, Young-Im;Baek, Mi-Hwa;Kim, Dong-Su
    • Resources Recycling
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    • v.16 no.4
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    • pp.27-32
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    • 2007
  • The characteristics of fluorine removal from wastewater have been investigated by precipitation method using calcium as a precipitant for the purpose of the reuse of treated wastewater. In the conditions of 10 mM of the initial concentration of fluorine and pH 4, the precipitation of fluorine was rapidly progressed within a few minutes after the precipitant was added and the precipitation of fluorine was observed to follow a second order reaction. Also, as the addition of precipitant was increased, the reaction rate constant of fluorine precipitation was found to rise. Postulating that the maximum fluorine removal was attained at pH 4, about 70% of fluorine was precipitated compared with the maximum removal when 10 times of equivalent amount of calcium was employed at pH 2 and the fluorine removal was about 96% compared with its maximum value at pH 3 under the same addition of precipitant. The fluorine precipitation reaction was found to be endothermic and the coexistence of $SiF_6{^{2-}}$ with fluorine resulted in its less removal. Finally, the isoelectric point of the precipitate was examined to be ca. pH 5.

A Study on the Tetrafluoroborate Decomposition Reaction and Removal of Fluoride Using Aluminum (알루미늄을 이용한 불화붕산염의 분해 반응 및 불소 처리에 관한 연구)

  • Joo, Hyun-Jong;Kim, Moon-Ki
    • Journal of Korean Society of Environmental Engineers
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    • v.35 no.4
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    • pp.257-262
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    • 2013
  • The fluorine-containing waste water tends to show a higher removal efficiency through the coagulative precipitation process with calcium. However the tetrafluoroborate produced from the etching process is difficult to remaval due to it's low reactivity with calcium. The objective of this study is improving the efficiency of fluoride ion removal in tetrafluoroborate through decomposing. Research on tetrafluoroborate decomposition depending on reaction pH, temperature, and aluminum dosage were conducted, using a laboratory-scale reactor. The result shows that the reaction of tetrafluoroborate with aluminum is faster with lower pH, higher water temperature, and higher Al/T-F (Aluminum/Total Fluoride) mole ratio. It is found that there was no big change in concentration after over 120 minutes of reaction. This study is to be able to improve the efficiency of tetrafluoroborate and fluoride wastewater treatment by using aluminum.

Surface and Corrosion Protection Properties of Fluorine Doped PVDF by Plasma Fluorination (플라즈마 불소화에 의해 제조된 불소 도핑 PVDF의 표면 및 부식방지 특성)

  • Kim, Seokjin;Lim, Chaehun;Kim, Daesup;Lee, Young-Seak
    • Applied Chemistry for Engineering
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    • v.32 no.6
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    • pp.653-658
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    • 2021
  • Polyvinylidene fluoride (PVDF) is a promising coating material because of its outstanding processability. The PVDF coating, however, has limitations in anti-corrosion application due to its weak hydrophobicity compared to that of other fluoropolymers. In this study, plasma fluorination was performed using carbon tetrafluoride (CF4) gas to improve anti-corrosion properties of PVDF. The fluorine content and hydrophobicity of PVDF were investigated in different CF4 flow rates, followed by the determination of anti-corrosion properties. The fluorine content on the surface of the PVDF film increased by up to 46.70%, but the surface free energy was independent of CF4 flow rate. Meanwhile, the surface roughness of the PDVF film tended to increase by up to 150% and then decrease with increasing CF4 flow rate. It is considered that the plasma fluorination affects the surface free energy due to the introduction of fluorine functional groups and surface etching. In addition, the degree of corrosion of the PVDF-coated Fe plate was significantly reduced from 49.2% to 19.0% compared to that of the uncoated Fe plate. In particular, the degree of corrosion of the fluorinated PVDF-coated Fe plate was 13.6%, which was 28.4% lower than that of the PVDF-coated Fe plate, showing improved anti-corrosion protection.