• Advances in environmental research
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• v.3 no.1
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• pp.29-43
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• 2014

Pharmaceutical wastewater effluents are well known for their difficult elimination by traditional biotreatment methods and their important contribution to environmental pollution due to its fluctuating and recalcitrant nature. OTC is one of the nonbiodegradable antibiotics that makes antibiotic-resistant, so it can make be high risk for environment. NZVI can be a good choice for removal of OTC in aqueous solution. Response surface methodology (RSM) was used to optimize the amounts of NZVI and OTC to be used at pH 3 and under 200 W, UV-A irradiation. The responses were removal percent of absorption at 290 and 348 nm, TOC and COD of OTC. In the optimum condition, Linear model was performed 155 ppm of OTC were removed by 1000 ppm NZVI after 6.5 hours and the removal efficiency of absorption at 290 and 348 nm, TOC and COD were 87, 95, 85 and 89 percent, respectively. In the similar process, there is no organic compound after 14 hours. The parameters ORP, DO and pH were investigated for 6:30 hours to study the type of NZVI reaction in process. In the beginning of reaction, oxidation was the dominant reaction after 3 hours, photocatalytic reaction was remarkable. The mechanism of OTC degradation is proposed by HPLC/ESI-MS and four by products were found. Also the rate constants (first order kinetic chain reaction model) were 0.0099, 0.0021, 0.0010, 0.0049 and $0.0074min^{-1}$, respectively.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.411-420
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• 2020

Undesirable interfacial reactions between the cathode and sulfide electrolyte deteriorate the electrochemical performance of all-solid-state cells based on sulfides, presenting a major challenge. Surface modification of cathodes using stable materials has been used as a method for reducing interfacial reactions. In this work, a precursor-based surface modification method using Zr and Mo was applied to a LiNi_0.6Co_0.2Mn_0.2O₂ cathode to enhance the interfacial stability between the cathode and sulfide electrolyte. The source ions (Zr and Mo) coated on the precursor-surface diffused into the structure during the heating process, and influenced the structural parameters. This indicated that the coating ions acted as dopants. They also formed a homogenous coating layer, which are expected to be layers of Li-Zr-O or Li-Mo-O, on the surface of the cathode. The composite electrodes containing the surface-modified LiNi_0.6Co_0.2Mn_0.2O₂ powders exhibited enhanced electrochemical properties. The impedance value of the cells and the formation of undesirable reaction products on the electrodes were also decreased due to surface modification. These results indicate that the precursor-based surface modification using Zr and Mo is an effective method for suppressing side reactions at the cathode/sulfide electrolyte interface.

• Bulletin of the Korean Chemical Society
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• v.21 no.7
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• pp.727-733
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• 2000

Analytical potential energy surfaces have been constructed for the four-center elimination of HCI from 1,1-dichloroethylene.The potential functions are Morse-type functions which are modified by appropriate switching and attenuating functions with adjustable parameters. The parameters have been found by fitting the calculated vibrational frequencies, reaction endothermicity, equlibrium geometries of the reactant and products to those of experiments and ab initio calculations. The translational energy release obtained from classical trajectory calculations on this surface is in good agreement with the experiment.

• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.328-332
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• 2012

Etch rates of Si and high purity SiC have been compared for various fluorocarbon plasmas. The relative plasma resistance of SiC, which is defined as the etch rate ratio of Si to SiC, varied between 1.4 and 4.1, showing generally higher plasma resistance of SiC. High resolution X-ray photoelectron analysis revealed that etched SiC has a surface carbon content higher than that of etched Si, resulting in a thicker fluorocarbon polymer layer on the SiC surface. The plasma resistance of SiC was correlated with this thick fluorocarbon polymer layer, which reduced the reaction probability of fluorine-containing species in the plasma with silicon from the SiC substrate. The remnant carbon after the removal of Si as volatile etch products augments the surface carbon, and seems to be the origin of the higher plasma resistance of SiC.

• Journal of the Korean institute of surface engineering
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• v.27 no.3
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• pp.123-133
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• 1994

Oxidation behavior of STS 304 and 430, produced by POSCO, Korea, was studied in order to study the surface defects formed during manufacturing processes. Oxidation experiments were carried out in a preheat-ed furnace at 850~$1, 250^{\circ}C$ in air and in a simulated coke oven gas(COG) atmosphere. The reaction products were examined by XRD, SEM and EDX on their surfaces and cross sections. Protective $Cr_2O_3$-primary oxide film was formed initially, but at critical point this film was broken and a duplex scale consisting of $Fe_2O_3$- and Fe$Cr_2O_4$- was formed. It was more severely attacked in a simulated COG atmosphere than in air, and STS 304 was superior to STS 430 in oxidation resistance.

• Journal of the Korean Applied Science and Technology
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• v.11 no.1
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• pp.71-77
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• 1994

In order to review industrial application of amphoteric surfactants, new types of hydroxy sulfobetaine, 3-(N, N-dimethyl N-dimethyl-N-alkylammonio)-2-hydroxy-1-propane sulfonate and 3-(N, N-dimethyl N-acylammonio)-2-hydroxy-1-propane sulfonate were prepared by the reaction of quaternized sodium 1-chloro-2-hydroxy-3-propane sulfonate with N, N-dimethyl-N-alkylamine and N, N-dimethyl N-acylamido propylamine that have a straight chain radical of 12, 18 carbon atoms respectively in the presence of alkali catalyst. All the reaction products could be separated by means of column and thin layer chromatography, and the yields of all products ranged in $85{\sim}90%$, the structure of them could be confirmed from IR and $^{1}H$-NMR spectra.

• Transactions on Electrical and Electronic Materials
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• v.15 no.1
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• pp.49-54
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• 2014

In this study, we carried out an investigation of the etch characteristics of silicon (Si) film, and the selectivity of Si to $SiO_2$ in $SF_6/O_2$ plasma. The etch rate of the Si film was decreased on adding $O_2$ gas, and the selectivity of Si to $SiO_2$ was increased, on adding $O_2$ gas to the $SF_6$ plasma. The optical condition of the Si film with this work was 1,350 nm/min, at a gas mixing ratio of $SF_6/O_2$ (=130:30 sccm). At the same time, the etch rate was measured as functions of the various etching parameters. The X-ray photoelectron spectroscopy analysis showed the efficient destruction of oxide bonds by ion bombardment, as well as the accumulation of high volatile reaction products on the etched surface. Field emission auger electron spectroscopy analysis was used to examine the efficiency of the ion-stimulated desorption of the reaction products.

• Food Science and Preservation
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• v.18 no.5
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• pp.721-728
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• 2011

1(3)-palmitoyl-2-oleoyl-3(1)-stearoyl-(POS)-glycerol-enriched reaction products were synthesized from camellia oil, palmitic ethyl ester, and stearic ethyl ester via lipase-catalyzed interesterification. Response surface methodology (RSM) was employed to optimize the production of the POS-enriched reaction product (Y1, %) and the stearicand palmitic-acid contents at the sn-2 position due to acyl migration (Y2, %). The reaction factors were the enzyme amount (X1, 2-6%), reaction time (X2, 60-360 min), and substrate molar ratio of camellia oil to palmitic ethyl ester and stearic ethyl ester (X3, 1-3 mol). The predictive models for Y1 and Y2 were adequate and reproducible as no lack of fit was signified (0.128 and 0.237) and as there were satisfactory levels of R2 (0.968 and 0.990, respectively). The optimal conditions for the reaction product for maximizing Y1 while minimizing Y2 were predicted at the reaction combination of 5.86% enzyme amount, 60 min reaction time, and 1:3 substrate molar ratio (3 moles of palmitic ethyl ester and 3 moles of stearic ethyl ester). Actual reaction was performed under the same conditions as above, and the resulting product contained 20.19% TAG-P/O/S and 12.71% saturated fatty acids at the sn-2 position.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.416-422
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• 1999

The characteristics of inductively coupled Cl$_2$/BCl$_3$ plasmas during the GaN etching were studied using plasma mass spectrometry by measuring the relative amounts of reactive ions, neutrals, and etch products. GaN etch rates increased with the increase of pressure and showed a maximum near 25mTorr for the pure $Cl_2$ and near 30mTorr for $Cl_2$$BCl_3$. The addition of$ BCl_3$ to $Cl_2$ also was increased GaN etch rates until 50%BCl$_3$ was mixed to $Cl_2$. The GaN etching with pure $Cl Cl_2$ appears to be related to the combination of Cl$_2^{+}$ ion bombardment and the chemical reaction of Cl radicals. In the case of the GaN etching with Cl$_2$/BCl$_3$, in addition to the combined effect of$_2^{ +}$ ions and Cl radicals, $_BCl2^{+ }$ ions appear to be responsible for some of GaN etching even though they do not have significant effect on the GaN etching compared to $Cl_2^{+}$ and Cl. $Ga^{+ }$ , $GaCl^{+}$ , $GaCl_2^{+}$ , and $N_2^{+}$ were observed as the positive ions of etch products, and the intensities of these etch products showed the same trends as those of GaN etch rate. Among the etch products, Ga and $N_2$ appear to be the main etch products.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.393-397
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• 1999

Among various reactions which metal sulfides can undergo in the reducing environment, the lattice exchange reaction was examined in a attempt to selectively remove heavy metal ions contained in the Fe-Coagulants acid solution. We have examined Zeta potential along with pHs to investigate surface characteristics of ${FeS}_{(s)}$. As a result of this experiment, zero point charge(ZPC) of FeS is pH 7 and zeta potential which resulted from solid solution reaction between Pb(II) and ${FeS}_{(s)}$ is similar to that of ${PbS}_{(s)}$. Solubility characteristics of ${FeS}_{(s)}$ is appeared to that dissolved Fe(II) concentration increased in less than pH 4, and also increased with increasing heavy metal concentration. Various heavy metal ions(Pb(II), Cu(II), Zn(II)) contained in Fe-coagulants acid solution were removed selectively more than ninety-five percent in the rang of pH 2.5~10 by ${FeS}_{(s)}$. From the above experiments, therefore, We could know that the products of reaction between heavy metal ions and $FeS_{(S)}$ are mental sulfide such as $PbS_{(S)}$, $CuS_{(S)}$ and $ZnS_{(S)}$.