• Tuberculosis and Respiratory Diseases
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• v.62 no.3
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• pp.223-226
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• 2007

Tetrafluoroethylene is a colorless gas that can be used to synthesize a variety of fluoride compounds by polymerization (e.g., Teflon). Fluoride compounds have many applications in industry. There are several reports of inhalation injury from the pyrolytic product of fluoride compounds. When the polymer is heated under the conditions of inadequate ventilation, the fumes can cause polymer fume fever or pulmonary edema which manifested as symptoms such as fever, chill, profuse sweating, cough and dyspnea. However there are no reports of a direct lung injury caused by tetrafluoroethylene. We report a case of a 27-year-old male presented with acute lung injury after inhaling concentrated tetrafluoroethylene. He complained of cough and dyspnea after the accidental inhalation of tetrfluoroethylene at his workplace. The symptoms improved without any complications after conservative treatment with oxygen and steroid.

• Journal of the Korean Chemical Society
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• v.13 no.1
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• pp.68-74
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• 1969

Flourination of Ethyl, ${\alpha},{\beta$}-dichloro-${\beta$}-phenyl propionate, Ethyl ${\alpha},{\beta$}-dibromo ${\beta$}-phenyl propionate, Ethyl ${\alpha},{\beta$}-dichloro ${\beta$}-(p-chloro-phenyl) propionate, and dibromostyrene by potassium fluoride were investigated in presence of dimethyl formamide, diethylene glycol, and diethylene glycol monomethyl-ether. The reactivity of these organic halogen esters and hydrocarbons towards potassium fluoride was checked further by means of radioactive fluorine-18. tracer. Generally, the reaction gave monofluoride together with dehalogenated olefin. The formation of olefine was increased when the reaction was done at high reaction temperature in presence of diethylene glycol, whereas the lower reaction temperature in presence of diethyleneglycol monomethyl ether favored the formation of mono fluoride in a good yield. The procedures and methods of the identification of monofluorides were described and the feasibility of this reaction of fluorine containing ester including the F-18 labelled compounds was discussed.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.2
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• pp.361-382
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• 1997

The effect of fluoride pretreatment upon root resorption after delayed replantation was studied in beagle dogs. Upper and lower incisors were extracted and bench dried for 45 minutes. 1% Stannous fluoride solution, 2% neutral sodium fluoride gel and 1.23% acidulated phosphate fluoride gel were used for the pre-treatment of replanted root surface in the experimental groups. Replantation was done with no treatment in control group. After of an experimental periods 3 weeks, animals were sacrificed by perfusion followed by sample preparation. A histomorphometric method was applied for evaluation of tissue reactions observed in each group under light microscope. Scanning electron microscopic observation was done to find out any different surface topography between groups. The results were as follows: 1. Fluoride-treated groups showed in general the better healing patterns than untreated control group. 2. Comparisons between three experimental groups revealed the general superiority of APF-treated group over the other groups in terms of tissue healing reaction by showing the highest frequency in uncomplicated healing pattern and surface resorption and the lowest in inflammatory resorption, but with no statistical significance(p>.05). 3. Scanning elecron micrographs showed the irregular distribution of resorption cavities and the attached bone of variable size and shape in all groups. 4. It can be concluded that the types of fluoride did not have significant impact on the early tissue reactions after delayed replantation under the condition of the present experiment.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.909-914
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• 2007

Fluorine compounds are the essential chemicals for wet processes of semiconductor and LCD production line. Problems of conventional treatments for fluoride wastewater are their high operation costs and low fluoride removal capacity. In this study, cement paste containing various Ca-bearing hydrates such as portlandite, calcium silicate hydrate(CSH), and ettringite was investigated for fluoride removal. The objectives of this study are to assess the feasibility of using cement paste cured mixture of cement and water as an alternative agent for treatment of fluoride wastewater and to investigate fluoride removal capacity of the cement paste. The performance of cement paste was comparable to that of lime in the kinetic test. In column experiment where the effluent fluoride concentrations were below 0.5 mg/L. Then the leached calcium reached the maximum level of 800 mg/L. The nitrate reduced to the level of less than 10 mg/L. Nitrate in the wastewater was exchanged with interlayer sulfate of these cement hydrate LDHs. Phosphate concentration could be reduced to 10 mg/L by forming calcium phosphate. These results indicate that the cement paste generally has advantageous characteristics as an economical and viable substitute for lime to remove fluoride.

• Journal of the Korean Chemical Society
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• v.7 no.3
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• pp.189-196
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• 1963

Reactions between potassium fluoride with organic halogen-containing carboxylic acids in dimethyl formamide solvent gave a decarboxylation reaction for the case of fluoro carboxylic acids of the type of $CF_3\;COOH,\;C_3F_7COOH,\;and\;C_2F_5COOH,$ whereas an additional partial fluorination together with dimerization reaction occurred for the chlorine containing acids of the type of $CH_2ClCOOH,\;CH_3CHClCOOH, \;CHCl_2COOH\;and\;o-Cl-C_6H_4-COOH.$ The phenyl halides showed no reactivity, but the halides with two electron attracting substituents on the benzene ring gave mainly dimerization reaction. The esters and alcohols gave an usual fluorination reaction. The same reactions in absence of the solvent at the elevated temperature increase the yield of the dimerized product and gave the cyclized product, fluorenone, in case of ο-chlorobenzoic acid. It was found that the fluorination usually precede the decarboxylation reaction by checking the stiochemical sequence of reaction. Catalytic influence of potassium fluoride were discussed and the mechanism of the reaction was considered.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.109-114
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• 2020

This work presents the results of laboratory scale tests of the CARBOFLUOREX (CARBOnate FLUORide EXtraction) process - a novel technology for the recovery of U and Pu from the solid fluorides residue (fluorination ash) of Fluoride Volatility Method (FVM) reprocessing of spent nuclear fuel (SNF). To study the oxidative leaching of U from the fluorination ash (FA) by Na₂CO₃ or Na₂CO₃-H₂O₂ solutions followed by solvent extraction by methyltrioctylammonium carbonate in toluene and purification of U from the fission products (FPs) impurities we used a surrogate of FA consisting of UF₄ or UO₂F₂, and FPs fluorides with stable isotopes of Ce, Zr, Sr, Ba, Cs, Fe, Cr, Ni, La, Nd, Pr, Sm. Purification factors of U from impurities at the solvent extraction refining stage reached the values of 10⁴-10⁵, and up to 10⁶ upon the completion of the processing cycle. Obtained results showed a high efficiency of the CARBOFLUOREX process for recovery and separating of U from FPs contained in FA, which allows completing of the FVM cycle with recovery of U and Pu from hardly processed FA.

• Journal of Oral Medicine and Pain
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• v.21 no.2
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• pp.207-224
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• 1996

This study was designed to determine the most effective concentration of fluoride and energy density of laser irradiation for the anticarious effect. For this study surface hardness in enamel was measured before and after irradiation with pulsed Nd;YAG laser and the topical application of fluoride. Of the permanent mandibular anterior hovine teeth, healthy, carious free ones were used. Three hundred specimens were made. Specimens within 25~45 Vickers hardness numbers were assigned to 20 control and experimental stoops ; each containing 15 specimens. After forming artificial carious lesions, 10 J/$\textrm{cm}^2$, 20 J/$\textrm{cm}^2$, and 30 J/$\textrm{cm}^2$ energies were irradiated on the enamel surface of each experimental group. Also NaF, NH4F, Elmex gel(amine fluoride) and APF gel fluoride compounds were applied topically. Next, all the specimens were placed into the pH circulatory procedures for eight days. Vickers hardness numbers were measured using a microhardness tester. Surface changes of the enamel were observed using an scanning electron microscope. The comparative ana1ysis yielded the following results : 1. The reduction of surface hardness of the enamel surface was less in all groups with fluoride application than in the group without fluoride application. 2. The APF gel croup with 10 J/$\textrm{cm}^2$ irradiation showed the lowest reduction of surface hardness. 3. The reduction of surface hardness of the enamel surface in the group of laser irradiation without fluoride application not showed any significant difference according to the energy density of the laser. 4. Under the scanning electron microscope, in enamel irradiated with 10J/$\textrm{cm}^2$ showed appearance similar to acid etching surface. In enamel irradiated with 20 J/$\textrm{cm}^2$, line enamel crack was detected. In enamel irradiated with 30j/$\textrm{cm}^2$, severe enamel crack and fusion of enamel were detected. These results suggest that one could obtain the best anticariogenic effects without damage to teeth in the group of application of APF gel after laser irradiation with 10 J/$\textrm{cm}^2$.

• Journal of the Korean Chemical Society
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• v.14 no.3
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• pp.201-206
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• 1970

Furfuryl acetate was chlorinated in presence of acetic acid using carbontetrachloride as the solvent. When the chlorination proceeded at the low concentration of acetic acid, the formation of the tetrachloride was more efficient than that of higher concentration. The chlorination done in presence of various Lewis acids such as aluminum chloride, hydrogen fluoride, and borontrifluoride could not give high yield of tetrachloride, but trichloride. In case of borontrifluoride and hydrogen fluoride, the decomposition of the reaction mixture was apparent. The results were discussed in terms of the stability of furfuryl nucleus towards an electron acceptor and the convenient procedure of preparing trichloro furfuryl acetate was described.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4449-4459
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• 2022

In this study, an NF₃ plasma etching reaction with a cobalt oxide (Co₃O₄) films grown on the surface of inorganic compounds using granite was investigated. Experimental results showed that the etching rate can be up to 1.604 mm/min at 380 ℃ under 150 W of RF power. EDS and XPS analysis showed that main reaction product is CoF₂, which is generated by fluorination in NF₃ plasma. The etching rate of cobalt oxide films grown on inorganic compounds in this study was affected by surface roughness and etch selectivity. This study demonstrates that the plasma surface decontamination can effectively and efficiently remove contaminated nuclides such as cobalt attached to aggregate in concrete generated when decommissioning of nuclear power plants.

• Clean Technology
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• v.19 no.2
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• pp.184-188
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• 2013

To increase flash point which is related to flammability, seven unprecedented new cleaning agents containing fluoride atoms have been invented. These newly synthesized cleaning agents's physical properties which were conducted by Korea Institute of Petroleum Management by using a standard method showed excellent values. Particularly, flash point of newly synthetic cleaning agents is more higher than that of fluoride free compound. A specimen for cleaning ability was prepared by cutting in $60mm{\times}40mm$ size of stainless steel plate. The surface of the above specimens was applied with four kinds of contaminants, such as paraffin based drawing oil, flux abietic acid, water-insoluble cutting oil, and lubricating oil. Contaminated specimens were immersed in new compounds (1-7) for 1 to 5 minutes to dissolve oil in the cleaning agent. Although the data indicate that all compounds (1-7) exhibit lower cleaning ability toward cutting oil, it is observed that in the case of the present study more than 80% of pollutants on the surface were almost removed within 5 minutes.