• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.29-33
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• 2010

In this study, boron, carbon, nitrogen and fluorine co-doped $TiO_{2}$ photocatalysts using tetraethylammonium tetrafluoroborate (TEATFB) have been prepared by different heat treatment temperatures to decrease the band gap. To explore the visible light photocatalytic activity of the novel low‐zband gap $TiO_{2}$ photocatalyst, the removal of two dyes was investigated, namely, acridine orange and rhodamine B. XRD patterns demonstrate that the samples calcined at temperatures up to $800^{\circ}C$ clearly show anatase peaks. The XPS results show that all the doped samples contain N, C, B and F elements and the doped $TiO_{2}$ shows the shift in the band gap transition down to 2.98 eV as UV-DRS results. In these UV-Vis results, photocatalytic activity of the doped $TiO_{2}$ is 1.61 times better than undoped $TiO_{2}$. Specially, excellent photoactivity results were obtained in the case of samples treated at $700^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.317-322
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• 2016

While PFOS sodium salt ($C_8F_{17}SO_3Na$) was not degraded by microorganisms for 28 days, the 4 alternatives were biodegraded at the rates of 21.6% for $C_{25}F_{17}H_{32}S_3O_{13}Na_3$, 20.5% for $C_{15}F_9H_{21}S_2O_8Na_2$, 15.8% for $C_{23}F_{18}H_{28}S_2O_8Na_2$ and 6.4% for $C_{17}F_9H_{25}S_2O_8Na_2$, respectively. The acute toxicity test using Daphnia magna was conducted for 48 hours, the half effective concentration ($EC_{50}$) of PFOS sodium salt ($C_8F_{17}SO_3Na$) was evaluated in 54.5 mg/L. While the 4 alternatives did not show any effect at 500.0 mg/L. The surface tension of the PFOS salt ($C_8F_{17}SO_3Na$) is 46.2 mN/m at a concentration of 500.0 mg/L. While the surface tension of the 4 alternatives was found to be superior to PFOS sodium salt ($C_8F_{17}SO_3Na$). The surface tension of $C_{23}F_{18}H_{28}S_2O_8Na_2$ (20.9 mN/m) has the lowest, followed by $C_{15}F_9H_{21}S_2O_8Na_2$ (23.4 mN/m), $C_{17}F_9H_{25}S_2O_8Na_2$ (27.3 mN/m), $C_{25}F_{17}H_{32}S_3O_{13}Na_3$ (28.2 mN/m). The four kinds of alternatives ($C_{15}F_9H_{21}S_2O_8Na_2$, $C_{17}F_9H_{25}S_2O_8Na_2$, $C_{23}F_{18}H_{28}S_2O_8Na_2$, $C_{25}F_{17}H_{32}S_3O_{13}Na_3$) were found to be superior to PFOS sodium salt ($C_8F_{17}SO_3Na$) in terms of biodegradation, Daphnia sp. acute toxicity and surface tension, and thus they were considered applicable as PFOS alternatives. Especially biodegradation rate of $C_{15}F_9H_{21}S_2O_8Na_2$, $C_{23}F_{18}H_{28}S_2O_8Na_2$ and $C_{25}F_{17}H_{32}S_3O_{13}Na_3$ was relatively high as 15.8~21.6%, and Daphnia sp. acute toxicity and surface tension were considerably superior (surface tension 39~55%) to PFOS sodium salt. Therefore, these alternatives are considered to be available as an alternative of PFOS.

• Clean Technology
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• v.15 no.2
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• pp.116-121
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• 2009

In this paper, we investigated the effect of an indirect oxidation zone in an electrolysis reactor that used Ti/$IrO_2$ as the anode and SUS 316L as the cathode. Based on our preliminary results, the electrolysis reactor was operated with pole plate interval of 6 mm, current density 1.0 $A/dm^2L$ and electrolyte concentration 15%. The removal efficiency, COD (chemical oxygen demand), was additionally increased by 55% and 12.5${\sim}$15.0% in the direct and indirect oxidation zones, respectively. The removal efficiencies of T-N (total nitrogen) and T-P (total phosphorus) were found to be 88% and 75%, respectively. It was shown that the additional effect of the indirect oxidation zone on the removal was nearly negligible. Also, as the removal of COD,T-N and T-P took place during the initial2${\sim}$5 days of reaction, it was concluded that there was no need to extend the retention time of the electrolysis reactor.

• Applied Biological Chemistry
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• v.17 no.2
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• pp.125-137
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• 1974

The chemical structure of glycolipid of Selenomonas ruminantium cell wall was to be elucidated. The bacterial cells were treated in hot TCA and the glycolipid fractions were extracted by the solvent $CHCl_3\;:\;CH_3OH$ (1 : 3). The extracted glycolipids fraction was further separated by acetone extraction. The acetone soluble fraction was named as the spot A-compound. The acetone insoluble but ether soluble fraction was named as the spot B-compound. These two compounds were examined for elucidation of their chemical structure. The results were as follows: 1. The IR spectral analysis showed that O-acyl and N-acyl fatty acids were linked to glucosamine moiety in the spot A-compound. However in the spot B-compound in addition to O and N-acyl acids phosphorus was shown to be attached to glucosamine. 2. It was recognized by gas liquid chromatography that spot A compound contained beta-OH $C_{13:0}$ fatty acid in predominance in addition to the fatty acid with beta-OH $C_{9:0}$, whereas the spot B compound was composed of the predominant fatty acid of beta-OH $C_{13:0}$ with small amount of beta-OH $C_{9:0}$. 3. According to the paper chromatographic analysis of hydrazinolysis products of the spot A compound, a compound of a similar Rf value as the chitobiose was recognized, which indicated a structure of two molecules glucosamine condensed. The low Rf value of the hydrazinolysis product of the spot B-compound confirmed the presence of phosphorus attached to glucosamine. 4. The appearance of arabinose resulting from. ninhydrin decomposition of the acid hydrolyzate of the spot A compound indicated that the amino group is attached to $C_2$ of glucosamine. 5. The amount of glucosamine in the N-acetylated spot A compound decreased in half of the original content by the treatment. with $NaBH_4$, indicating that there are two molecules of glucosamines in the spot A compound. The presence of 1, 6-linkage between two molecules of glucosamine was suggested by the Morgan-Elson reaction and confirmed by the periodate decomposition test. 6. By the action of ${\beta}-N-acetyl$ glucosaminidase the N-acetylated spot A compound was completely decomposed into N-acetyl glucosamine, whereas the spot B compound was not. This indicated the spot A compound has a beta-linkage. 7. When phosphodiesterase or phosphomonoesterase acted on $^{32}P-labeled$ spot B compound, $^{32}P$ was not released by phosphodiesterase, but completely released by phosphomonoesterase. This indicated that one phosphorus is linked to glucosamine moiety. 8. The spot A compound is assumed to have the following chemical structure: That is glucosaminyl, ${\beta}-1$, 6-glucosamine to which O-acyl and N-acyl fatty acids are linked, of which the predominant fatty acid is beta-OH $C_{13:0}$ fatty acid in addition to beta-OH $C_{9:0}$ fatty acid 9. The spot B compound is likely to have the linkage of $glucosaminyl-{\beta}-1$, 6-glucosamine to which phosphorus is linked in monoester linkage. Furthermore both O-acyl and N-acyl fatty acids contained beta-OH $C_{13:0}$ fatty acid predominantly in addition to beta-OH $C_{9:0}$ fatty acid.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.58-65
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• 2010

AlN thin films were deposited on sapphire substrates and ZnO templates by rf-magnetron sputtering. Powder-sintered AlN target was adopted for source material. Thickness of AlN layer was linearly dependent on plasma power from 50 to 110 W, and it decreased slightly when working pressure increased from 3 to 10 mTorr due to short mean free path of source material sputtered from AlN target by Ar working gas. When $N_2$ gas was mixed with Ar, the thickness of AlN layer decreased significantly because of low sputter yield of nitrogen. AlN layer was also deposited on ZnO template. However, it showed weak thermal stability that the interface between AlN and ZnO was deteriorated by rapid thermal annealing treatment above $700^{\circ}C$. In addition, ZnO layer was largely attacked by MOCVD ambient gas of hydrogen and ammonia around $700^{\circ}C$ through inferior AlN layer deposited by sputtering. And AlN layers were fully peeled off above $900^{\circ}C$.

• Clean Technology
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• v.20 no.4
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• pp.390-397
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• 2014

This study was performed to investigate the effects of fluidizing media on $N_2O$ production in fluidized bed incineration of sewage sludge. The fluidized media were prepared in a form of 2 mm bead by mixing zeolite powders in our lab. Sand having 0.4 mm of the mean size showed 0.44 m/s of minimum fluidization velocity ($U_{mf}$), while the prepared zeolite media 0.5 m/s. When the ratio of fluidizing media height to the inside diameter of the incinerator (bed aspect ratio) increased from 1.4 to 3.1, it was found that $U_{mf}$ of the zeolite media was varied from 0.5 m/s to 0.7 m/s. Under the operation conditions in 1.79 of excess air ratio, $909^{\circ}C$ of bed temperature and ca. 1.65 m/s of superficial velocity, as the weight of fluidizing meadia was increased, $O_2$ concentration in the flue gas was slightly decreased, and $CO_2$ increased. Above 6 kg of fluidizing media weight (1.98 of bed aspect ratio), it was observed that $N_2O$ concentration was significantly reduced, which might result from the decomposition of $N_2O$ on the zeolite media rather than transformation of $N_2O$ to NOx. On the other hand, in a variation of the zeolite media mixing ratio to sand and bed temperature at a constant total bed height, significant difference was exhibited in $N_2O$ emission concentration according to the temperature. Considering the operation temperature in the incineration, the effective calcination temperature of the zeolite media was suggested to be around $900^{\circ}C$.

• Journal of the Korean Institute of Gas
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• v.4 no.2 s.10
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• pp.1-6
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• 2000

In this experiment, we made the plasma reactor which adhere needle electrode in order to treat safely an NOx which was included in the gas. Also we experimently investigated characteristics of equipment and inspected efficiency. As a reaction gas, by using mixture gas of $NO/N_2$ and $N_2/O_2$, we setted up initial NO concentration and gas flow rate was set at 2 ${\iota}$/min. As a reaction characteristics of NOx, when discharge input power was high, NO concentration decreased and when the oxygen concentration increased, the NO decomposition was easy and decomposition energy efficiency was high. Also in case that NO concentration increased, NO decomposition energy efficiency was high but decomposition rate was low. The characteristics of ozone, when discharge input power was high, ozone increased and when $NO/N_2$ concentration increased, the ozone decreased.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.772-775
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• 2013

We have grown a p-GaN film on sapphire by MOCVD and explored the post-annealing effort on the film after depositing a $2500{\AA}$ thick $SiO_2$ protective layer on it. By etching the $SiO_2$ protective film after the heat treatment, the hole concentration was measured, and compared with the data values before the heat treatment. In addition to the concentration, the hole mobility was also monitored while varying the atmospheric gas ratio of $N_2$ and $O_2$, the rapid thermal annealing temperatures ($750^{\circ}C$ and $650^{\circ}C$) and times (1 to 15 min.) In order to investigate the optical and structural properties of the film, room temperature and low temperature PL measurements were conducted.

• Journal of the Korean Chemical Society
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• v.24 no.4
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• pp.288-294
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• 1980

Methanolysis rate constants were determined for $CH_3O(CO)Cl,\;CH_3S(CO)Cl\;and\;CH_3S(CS)Cl\;in\;CH_3OH-CH_3CN$ mixtures. Results show that the rates are not predominantly influenced by the bulk solvent properties but are partly influenced by specific electrophilic solvation.Polarity of the solvent is not a dominant factor but it nevertheless plays a role in charge stabilization of the $S_N1$ like transition state. The methanolysis proceeds through $S_N1$ mechanism for $CH_3S(CS)Cl$ for which both specific solvation of leaving group by methanol and charge stabilization by a high dielectric medium are important, while for $CH_3O(CO)Cl\;methanolysis occurs\;via\;S_N2$ mechanism in which both of the solvent effects are unimportant.

• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.1-5
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• 2000

Cathodoluminescence(CL) properties of ZnO:Zn green phosphor were investigated. ZnO:Zn phosphor was synthesized by varying reducing agents and firing temperatures. ZnS, charcoal and 5% H2 gas mixed with 95% N2 gas(5H2-95N2) were used as the reducing agent and atmosphere. The highest CL intensity of ZnO:Zn phosphor was observed under the condition of 5H2-95N2 atmosphere and firing temperature of 90$0^{\circ}C$ for 1h. Charocal and ZnO as reducing agents in the syntehsis of ZnO:Zn phosphor exhibited about 60% and 40%, respectively, of the CL intensity obtained with 5H2-95N2 atmosphere.