• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.635-637
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• 2014

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1409-1412
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• 2012

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.1
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• pp.25-32
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• 2005

The purpose of this study was to examine an effect of fluoride recharging on fluoride release and surface change of fluoride-releasing restorative materials. Six commercially available fluoride releasing restorative materials (Fuji II LC Improved: FL, Compoglass F: CF, Dyract AP: DA, F2000: FT, Gradia Direct: GD, and Tetric Ceram: TC) were selected as experimental materials. Disk specimens were fabricated with split teflon mold to the final dimensions of 15 mm in diameter and 1 mm in thickness. Ten samples of each material were fabricated and stored in deionized water at $37^{\circ}C{\pm}1^{\circ}C$ for 3 months. Before fluoride recharging, all specimens were polished sequentially from #800 to #2000 emery papers. Fluoride recharging was done at 5-day interval using 2.0% NaF gel. The release of fluoride into the storage water was monitored using a fluoride ion electrode. Data were analyzed by one-way ANOVA and Tukey's multiple range test. The results obtained were summarized as follows; 1. Fluoride recharge capability were FL > CF > DA and TC group after 12 times exposure to 2.0% NaF gel (P<0.05). 2. All the experimental materials, except for FT group, showed the increase of fluoride release and surface roughness. 3. Fluoride-releasing rates returned to base line within 3 days.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.684-688
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• 2007

The results of potentiostatic electrolysis of aqueous solution containing fluoride by bipolar packed bed electrolytic cell filled with granular aluminium were summarized. Removal efficiency of fluoride ion which it analyzed with ion chromatograph were 53, 73, 90% in applied voltage. Control the concentration of supporting electrolyte were 10, 30, 50, 70 mg/L and volume of packing material were 0, 25, 50, 75%, respectively, the quantity of electricity was $2.58A{\cdot}hr$ when the concentration of supporting electrolyte was 50 mg/L and the volume of packing material was 75%. As the results of electrolytsis of fluoride aqueous solution containing fluoride 10, 30, 50, 70 mg/L for 3 hours at 10 V, the removal efficiency of fluoride were 93.3, 80, 68.6%. Then the quantity of electricity were 2.58, 3.89, $5.43A{\cdot}hr$ and the fluoride removal amounts per quantity of electricity were 4.0, 3.5, $2.0mg/A{\cdot}hr$.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.136-143
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• 2005

The replacement of dental restorations due to secondary caries is a continuing problem in restorative dentistry. The secondary caries can be partly prevented by using fluoride containing dental materials such as glass ionomer cement, which releases and be recharged with fluoride ion acting as a fluoride reservoir. For the purpose of investigating the behaviors of fluoride release and recharge of conventional and high viscosity glass ionomer cements, the experiment was performed on the seven specimens each from 4 kinds of materials ; 1 kind of conventional glass ionomer cement, 2 kinds of high viscosity glass ionomer cements and 1 kind of composite resin. The amount of fluoride release was measured over 7 days with pH/ion meter and fluoride specific electrode. After measuring daily fluoride release, the specimens were recharged with 2% NaF solutions for 4 minutes and measured for 3 days with recharging repeated two consecutive times. The results were as follows : 1. Significantly more fluoride was released at first day after recharge in all materials except Z-100. 2. High viscosity glass ionomer cements released more or nearly equal amount of fluoride after recharge compared with the initial release(P<0.05). 3. The fluoride release after recharge with 2% NaF solution was in order of Fuji IX, Ketac Fil, Ketac Molar, Z-100.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.3
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• pp.248-255
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• 2016

The leaves of three plant species, such as soybean, raspberry, and kudzu, exposed to hydrogen fluoride was collected in an area surrounding an emission source where the release accident occurred. The ultrasonic-assisted extraction and analysis of fluoride by ion chromatography was carried out. The mean concentration of fluoride in the leaves of three plant species exposed to hydrogen fluoride was $5,409{\pm}1,198mg\;F/kg\;dry\;wt$ and $788{\pm}339mg\;F/kg\;dry\;wt$, respectively. The mean fluoride concentration in ambient air were estimated to be $2.36{\pm}0.65mg/m^3$ ($2.89{\pm}0.79ppm$) and $0.35{\pm}0.15mg/m^3$ ($0.43{\pm}0.19ppm$) in exposed and unexposed sites, respectively. It seems likely that the passive monitoring using plant leaves could identify with respect to plant risk by fluoride in atmosphere.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.35-40
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• 2013

The present study was conducted to investigate the adsorption potential of red mud for fluoride removal. Different operation parameters such as the effect of contact time, initial concentration, pH, competing anions, seawater, adsorbent dose amount, and adsorbent mixture were studied. Nearly 3 hr was required to reach sorption equilibrium. Equilibrium sorption data were described well by Langmuir model and the maximum adsorption capacity of red mud was 5.28 mg/g. The fluoride adsorption at pH 3 was higher than in the pH range 5-9. The presence of anions such as sulfate, nitrate, phosphate, and bicarbonate had no significant effect on fluoride adsorption onto red mud. The fluoride removal by red mud was greater in seawater than deionized water, resulting from the presence of calcium and magnesium ion in seawater. The use of red mud alone was more effective for the removal of fluoride than mixing red mud with other industrial waste such as oyster shells, lime stone, and steel slag. This study showed that red mud has a potential application in the remediation of fluoride contaminated soil and groundwater.

• Ecology and Resilient Infrastructure
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• v.5 no.1
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• pp.19-24
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• 2018

Water quality is affected by the pollutants flowing into rivers since the interaction between water bodies and sediments in various environmental conditions. Especially, accumulation of sediments increases in the stagnant water areas due to a relative long hydrological retention time in the water bodies. Therefore, it is an important factor of water quality to understand characterization of the material behavior in water bodies and sediments. In this study, the objective of the conditional experiments was small and medium sized streams located in Gyeonggi-do. To estimate how the changes of fluoride behavior, depending on the pH, ion type, concentration, and clay contents. The pH results showed a trend that adsorption amount of fluorine decreased and the dissolution of fluorine increased following by pH increasing. The concentration and type of ions results showed that $Cl^-$ and $SO{_4}^{2-}$ ions had no significant effect on the adsorption ability of fluorine, the amount of dissolution was increased because $OH^-$ ion had active competition with fluorine in the reaction. The ingredient of sediment results showed that the amounts of fluoride adsorption and dissolution were reduced in samples, which contain relatively large amounts of Silt and Clay components. This means that the environmental conditions of water bodies greatly affect the adsorption and dissolution of fluoride in the sediments, so that proper management of fluoride in the sediments must precede an understanding of the environmental conditions of the water bodies.

• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.258-263
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• 2018

This study attempted to utilize ultrafine precipitated calcium carbonate for fluoride removal from the wastewater of electronics industries. An average particle size of the calcium carbonate was $0.96{\mu}m$, and pH of the aqueous slurry was 10 with 70% in mass. The suspension solution showed approximately 2 mL/hr of the sedimentation rate. The present calcium carbonate solution could be comparable to the conventional aqueous calcium source, $Ca(OH)_2$, for the neutralization and removal of fluoride ions. Depending on the amount of an additional alkali source, less amounts of test Ca-source slurries were required to reach the solution pH of 7.0 than that of using the aqueous calcium hydroxide. It was also found from XRD analysis that more calcium fluoride precipitates were formed by the addition of calcium carbonate solution rather than that of calcium hydroxide. In addition, Minteq equilibrium modelling estimated various ion complexes of fluoride and calcium in this process.

• Journal of the Korean Chemical Society
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• v.45 no.2
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• pp.143-148
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• 2001

In this study, open tubular capillary columns for ion charomatography were developed to analyze trace amount of ions in samples. When small I,D. capillary column length is 1.0~5.0 m. The capillary columns were made using fused silica capillary(I.D:50㎛) and DMEOHA latex particles. The new conductivity cell and suppressor were also developed and made for capillary column ion chromatography. When several anions(fluoride, nitrite, nitale,chlorate,phosphte, sulfate) were analyzed using these capillary columns. reproducible and good chromatograms were obtained.