• Journal of the Korean Chemical Society
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• v.59 no.2
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• pp.142-147
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• 2015

Two new chitosan derivatives, polyamine grafted chitosan copolymers have been synthesized for corrosion protection of carbon steel in acidic medium. First, methyl acrylate graft chitosan copolymer (CS-MAA) was prepared by the reaction of chitosan (CS) and methyl acrylate (MAA) via the Michael addition reaction. Then, CS-MAA was reacted with ethylene diamine (EN) and triethylene tetramine (TN) respectively to synthesize ethylene diamine grafted chitosan copolymer (CS-MAA-EN) and triethylene tetramine grafted chitosan copolymer (CS-MAA-TN), and the structures were characterized by Fourier-transform infrared spectroscopy (FT-IR). At last, the corrosion inhibition activities on Q235 carbon steel were investigated by using gravimetric measurements, metallographic microscope, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The compounds CS-MAA-EN and CS-MAA-TN show an appreciable corrosion inhibition property against corrosion of Q235 carbon steel in 5% HCl solution at $25^{\circ}C$. It has been observed that CS-MAA-EN shows greater corrosion inhibition efficiency than CS-MAA-TN. The inhibition efficiency of CS-MAA-EN was close to 90% when the mass fraction concentration was 0.2%~0.3%; the inhibition efficiency of CS-MAA-TN was close to 85% when the mass fraction concentration was 0.02%. The present work provided very promising results in the preparation of green corrosion inhibitors.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.83-88
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• 1999

This study was carried out to examine the behavior of THM formation in water treated with chlorine dioxide where humic acid was used as THM precursor. THM was not detected in bromide-free water, but formed in water containing bromide. When 10 mg/l of chlorine dioxide was added to water containing 5 mg/l of humic acid and bromide respectively, 20.46 ${\mu}$g/l of THM was formed. It is postulated that chlorine dioxide oxidize bromide to hydrobromous acid, which subsequently reacted with humic acids similar to chlorine reaction. The formation of THM could be reduced at low pH. Among THM formed, CHBr$_3$ was the predominant species in the alkaline solution, while CHCl$_3$ in the acidic solution. A sample pretreated with chlorine dioxide for 24h before addition of chlorine showed a reduction of 75.1% in THM formation, compared with a sample not pretreated with chlorine dioxide and a sample treated by chlorine for 24h prior to addition of chlorine dioxide also showed a reduction of 37.8% in THM formation, compared with a sample not added with chlorine dioxide. It may explain that chlorine dioxide oxidizes directly a fraction of THM.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.1
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• pp.39-45
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• 2018

Ammonia Adsorbed Fly Ash (AAFA) samples produced from coal fired plants equipped with SNCR (Selective Non-Catalytic Reduction) of nitrogen oxides with urea have been chemically analyzed, and their physical and dissolution properties have been investigated. XRD results for the ammonia component in AAFA ascertained that ABS (ammonium bisulfate) and AS (ammonium sulfate) were deposited on fly ash as $SO_3$ reacted with unreacted ammonia at SNCR. SEM and EDS images showed that fine ashes on large fly ash surface of sphere type were agglomerated, due to adhesive role of ammonium salts attached fly ashes. Dissolution test results of ammonium salts absorbed on AAFA in distilled water or sea water showed that the proportion of un-ionized $NH_3$ to $NH_4{^+}$ were primarily a function of pH and temperature. Increasing pH and temperature causes an increase in the fraction of un-ionized $NH_3$. At pHs of 9.6 and 10.7, un-ionized $NH_3$ and $NH_4{^+}$ ions are present in equal amounts at distilled water and sea water, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.134-137
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• 2009

Commercially available elemental powders of Cu, Zn, Sn and Se were employed for crystallizing a stannite-type $Cu_2ZnSnSe_4$ compound by means of solid state reaction. $Cu_2ZnSnSe_4$ reaction chemistry was also modeled based on differential-thermal analysis and X-ray powder diffraction results. It was observed that Se tends to react preferably with Cu to form CuSe and $CuSe_2$ phases at low reaction temperature. The formation of $Cu_5Zn_8$ intermetallic phase was found to be the intermediate reaction path for the binary ZnSe formation. A solid state reaction at $320^{\circ}C$ reacted elemental powderst obinary selenides of CuSe, ZnSe and SnSe completely. The crystallization of $Cu_2ZnSnSe_4$ was was detected to begin at $300^{\circ}C$ and its weight fraction increased with an increase of reaction temperature, which most probably formed from the reaction between $Cu_2SnSe_3$ and ZnSe.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.2
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• pp.39-45
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• 2003

This study was performed to develop the new type enzyme immobilization sheet from carboxymethylated refiner mechanical pulp (CRMP) substrate. Enzyme immobilization was attempted to couple carboxyl groups of CRMP with amino groups of the enzyme, trypsin, through the reaction of carbodiimide reagent, 1-ethyl-3-(3-dimethyl aminopropyl)-carbodimide (EDC ). Immobilization carrier, water insoluble CRMP fraction (CRMP-IS), was successfully reacted with the enzyme, formed peptide linkage like -CONH- at 1680$cm^{-1}$ / and new ester linkage like -COO$CH_3$, methylester at 1735$cm^{-1}$ /, and produced enzyme immobilized substrate (CRMP-IST). The enzyme immobilized handsheet was prepared by mixing the above chelated enzyme immobilized substrate(CRMP-IST) with kraft pulp by paper sheet machine like papermaking process. The sheet weight and strength were increased with increasing dosage of CRMP-IST, and decreased at more than 10％ mixing of CRMP-IST, but higher than the controls. Concerning activities of immobilized trypsin(CRMP-IST) sheet by caseinolysis, the teared-off sheet with shaking was shown higher enzyme activities than sheet shape without shaking. In conclusion, this enzyme immobilized sheet would be expected easy handling for practical application and reutilization.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.17-20
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• 2002

The effects of relatively low lead content (0.2~0.3) on the 2223 phase formation and transport property of Bi-2223/Ag tapes have been investigated. The results show that lead contents have great impact on the phase assemblage of precursors, subsequently, on the phase formation and transport property of silver sheathed BSCCO-2223 tapes. Powders containing Pb=0.25 and Pb=0.3 resulted in the nearly identical $J_c$ values in fully processed tapes, but leaded to significant difference on the phase formation process. For the case of Pb=0.2, both low conversion fraction of 2212 to 2223 and low $J_c$ value were obtained in final reacted tape, which was probably due to lack of enough liquid phase to facilitate the phase transformation.

• Journal of the Korean Chemical Society
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• v.21 no.1
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• pp.67-72
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• 1977

Author studied on the isolation technique and properties of the products obtained by the reaction of soybean oil with maleic anhydride. Before studying above purpose, oleic acid and linoleic acid contained in soybean oil were reacted with maleic anhydride. Thin-layer chromatography using silica coated plate and solvent system consisting of petroleum ether-diethyl ether = 7:3∼5:5 (v/v) resulted in good effects on the isolation of maleic anhydride adducts. Four fractions were separated and fraction No. 2 were analyzed by IR & UV spectrophotometer, obtaining the following conclusions. In the case of oleic acid adduct and linoleic acid adduct, it were conjectured that the succinic acid type adduct was formed. In the case of conjugated $C_{18}$ fatty acid adduct, cyclohexene type adduct was formed which differed from oleic acid and linoleic acid adduct.

• Journal of the Korean Ceramic Society
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• v.26 no.3
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• pp.416-422
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• 1989

The particle size of synthesized SiC powders was decreased with increasing carbon content when the mixture of carbon and silica was carbonized at 1, 45$0^{\circ}C$ after hydrolysis of the mixture with the ranges of 3.1 to 3.5 in the mole ratio of Carbon/Alkoxide. The reacted fraction of $\beta$-SiC nearly had nothing to do with the mole ratio of Carbon/Alkoxide. When the reaction was made by adding 0.5wt% additives in the composition of 3.1 in the mole ratio of carbon/alkoxide, the additives decreased the yield of $\beta$-SiC and its sequence was Ba2O3>B>Fe>Al>Al2O3>Si. The effect of additives promoted the transformation of $\beta$-SiC to $\alpha$-SiC form and shwoed the increasing tendency of lattice constant. The two colors of $\beta$-SiC powder came out : one was the black grey with addition of Al, Al2O3 and B the other the light grey with addition of Fe, B2O3 and Si.

• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.100-106
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• 2007

The objective of this study was to evaluate the efficiency of $(NH_4)_2HPO_4$, $Na_2HPO_4{\cdot}12H_2O$, $CaHPO_4{\cdot}2H_2O$, $Ca(H_2PO_4)_2{\cdot}H_2O$ and $H_3PO_4$ for the stabilization of soils contaminated with multi-metals containing Pb, Cd and As. The application rate of stabilizers to soils was determined based on $PO_4/Pb_{total}$ molar ratio of 0.5, 1, 2, 4. The results of Korea Standard Test and TCLP (EPA Method 1311) showed the reduction of metal leachabilities below the regulatory limits for Pb and Cd when $H_3PO_4$ and $Ca(H_2PO_4)_2{\cdot}H_2O$ were applied. However, stabilization efficiency for Cd was low and in case of As leaching concentration increased rather. It is considered that $PO_4$ reacted effectively $Pb^{2+}$ due to leaching Pb under low pH condition created by adding $H_3PO_4$. Accordingly Pb was stabilized by dissolution and precipitation of hydroxypyromorphite. From the change of metals fraction using sequential extraction procedure when $H_3PO_4$ applied as a stabilizer, we confirmed that residual fraction increased more than 60% and this result was accorded with XRD analysis that detected only hydroxypyromorphite peak in $H_3PO_4$.

• Parasites, Hosts and Diseases
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• v.31 no.3
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• pp.269-276
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• 1993

To ascertain that tegument of Pnragonimus westermoni has specific antigenic proteins, the tegumental fraction was isolated from 10-month-old worms by 0.1% digitonin solution, and subjected to SDS-PAGE and immunoblot. Component proteins of tegumental syncytium comprised of 94, 74 (76-66), 62, 54, 44, 42, 38, 28, 26, 25, 24, 17, 15.5 and 13.5 kDa proteins. Of them, the 94, 44 and 42kDa proteins were more specific to tegument, especially the 94 kDa protein was the most prevailing one. In immunoblot, antigens of the 94, 90, 78, 76, 74, 68, 65, 63, 60, 59 and 54 kDa proteins were commonly detected by 7 sera of 10 human paragonimlasis, but none of them reacted with 5 sera of clonorchiasis. In conclusion, the 94 kDa protein was the major tegumental protein, as well as the specific antigen. The 76 and 66 kDa proteins were the minor components of tegument, which were also specific antigens of R westermcni.