• 한국연소학회지
• /
• 제5권2호
• /
• pp.37-50
• /
• 2000

In the present study, a systematic chemical kinetic calculations were made to investigate the augmentation of $NO-NO_2$ conversion due to the addition of various hydrocarbons (methane, ethylene, ethane, propylene, propane) in the nonthermal plasma treatment. It is included in the present conclusion that the reaction between hydrocarbon and oxygen radicals induced by electron collision, is believed to be a primarily process for triggering the overall NO oxidation and the eventual NOx reduction. Upon the completion of the initiating step, various radicals (OH, $HO_2$ etc.) successively are produced by hydrocarbon decomposition form the primary path of $NO-NO_2$ conversion. When the initiating step is not activated, hydrocarbon consumption rate appeared to be very low, thereby the targeted level of NO conversion can only be achieved by the addition of more input energy. Present study showed ethylene and propylene to have higher affinity with O radical under all conditions, thereby both of these hydrocarbons show very fast and efficient $NO-NO_2$ oxidation. It was also shown that propylene is superior to ethylene in the aspect of NOx removal.

• Bulletin of the Korean Chemical Society
• /
• 제33권11호
• /
• pp.3539-3543
• /
• 2012

Butacaine sulfate is an ester of p-aminobenzoic acid which has been widely used as a local anaesthetic and it is a long standing agent particularly for spinal anaesthesia. For this reason, a kinetic study of oxidation of butacaine sulfate by sodium N-chlorobenzenesulfonamide (chloramine-B or CAB) has been carried out in $HClO_4$ medium at 303 K in order to explore this redox system mechanistic chemistry. The rate shows a first-order dependence on both $[CAB]_o$, and $[substrate]_o$, and a fractional-order dependence on acid concentration. Decrease of dielectric constant of the medium, by adding methanol, increases the rate of the reaction. Variation of ionic strength and addition of benzenesulfonamide or NaCl have no significant effect on the rate. The reaction was studied at different temperatures and the activation parameters have been evaluated. The stoichiometry of the reaction has been found to be 1:2 and the oxidation products have been identified by spectral analysis. The observed results have been explained by plausible mechanism and the related rate law has been deduced.

• 열처리공학회지
• /
• 제8권2호
• /
• pp.137-148
• /
• 1995

The nitridation kinetics of titanium powder were studied by isothermal and non-isothermal (dynamic) methods in high purity nitrogen under I atm pressure. For the comparison with nitridation, the oxidation kinetics of titanium powder were also studied in dry oxygen at I atm pressure. An automatic recording electrobalance was used to measure the weight gain as a function of time and temperature. For the reaction with nitrogen, the nitride was formed at over $700^{\circ}C$. The reaction with nitrogen followed the parabolic rate law, and the activation energy was calculated to be 31 kcal/mol in the isothermal method (above $900^{\circ}C$). The non-stoichiometric TiNx has been synthesized by the nitridation at a proper temperature and time, followed by the homogenizing treatment above $1100^{\circ}C$. In comparison with the stoichiometric $TiN_{1.0}$ and the non-stoichiometric TiNx ($TiN_{0.5}$ and $TiN_{0.65}$), the hot oxidation characteristics of the former is superior to that of the latter. However, both non-stoichiometric nitrides make little difference in the hot oxidation characteristics.

• Bulletin of the Korean Chemical Society
• /
• 제8권5호
• /
• pp.389-393
• /
• 1987

The oxidation of carbon monoxide by gaseous oxygen on 0.53, 1.02, and 1.51 mol $\%$CoO-doped $-Fe_2O_3$ catalysts has been investigated in the temperature range from 340 to 480$^{\circ}C$ under various CO and $O_2$ partial pressures. The oxidation rates have been correlated with 1.5-order kinetics; the 0.5-order with respect to $O_2$ and the first-order with respect to CO. In the above temperature range, the activation energy is 0.34 $\pm$ 0.01 eV${\cdot}$$mol^{-1}$. The electrical conductivity of 0.53, 1.02, and 1.51 mol %CoO-doped $\alpha$-$Fe_2O_3$ has been measured at 350$^{\circ}C$ under various $P_{CO}and $P_{O_2}$. From the conductivity data it was found that $O_2$ was adsorbed on Vo formed by doping with CoO, while CO appeared essentially to be chemisorbed on the lattice oxygen of the catalyst surface. The proposed oxidation mechanism and the dominant defect were supported by the agreement between the kinetic data and conductivities.

• Bulletin of the Korean Chemical Society
• /
• 제15권8호
• /
• pp.616-622
• /
• 1994

The oxidation of carbon monoxide by gaseous oxygen in the presence of a powdered $Nd_{1-x}Sr_xCoO_{3-y}$ solid solution as a catalyst has been investigated in the temperature range from 150$^{\circ}$C to 300$^{\circ}$C under various CO and $O_2$ partial pressures. The site of Sr substitution, nonstoichiometry, structure, and microstructure were studied by means of powder X-ray diffraction and infrared spectroscopy. The electrical conductivity of the solid solution has been measured at 300$^{\circ}$C under various CO and $O_2$ partial pressures. The oxidation rates have been correlated with 1.5-and 1.2-order kinetics with and without a $CO_2$ trap, respectively; first-and 0.7 order with respect to CO and 0.5-order to $O_2$. For the above reaction temperature range, the activation energy is in the range from 0.25 to 0.35 eV/mol. From the infrared spectroscopic, conductivity and kinetic data, CO appears essentially to be adsorbed on the lattice oxygens of the catalyst, while $O_2$ adsorbs as ions on the oxygen vacancies formed by Sr substitution. The oxygen vacancy mechanism of the CO oxidation and the main defect of $Nd_{1-x}Sr_xCoO_{3-y}$ solid solution are supported and suggested from the agreement between IR data, conductivities, and kinetic data.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2000년도 추계학술발표강연 및 논문개요집
• /
• pp.68-68
• /
• 2000

• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2001년도 추계총회 및 학술발표회
• /
• pp.9-9
• /
• 2001

• Environmental Analysis Health and Toxicology
• /
• 제14권3호
• /
• pp.121-126
• /
• 1999

The present paper describes a study of the photochemical kinetics and its oxidation mechanism of DBT. The photolysis of DBT in aqueous solution media have shown to have significant oxidation activities for the photolytic desulfurization of DBT. The oxidation effect was more pronounced in 4 % NaCl solution. A mechanism was proposed that the desulfurization process arise from the substution of sulfur by the hydroxyl radicals in different aqueous medium.

• 한국수산과학회지
• /
• 제15권1호
• /
• pp.83-93
• /
• 1982

In this work, lipid oxidation and the kinetics of the oxidation reaction in fried file-fish meat were investigated when sun-dried file-fish was stored under the conditions of various water activities and temperature, 35, 45, 55 and $35/55^{\circ}C$. The storage stability and the development of browning by oxidative rancidity were also discussed. Monolayer coverage value of water content in dried file-fish was $8.03\%$ at $0.21\;a_w$Lipid oxidation at $35^{\circ}C$ was developed with increasing water activity but at $45^{\circ}C$and $55^{\circ}C$ it was rapidly progressed without clear differences between water activities except $0.44\;a_w$. The rate of reaction was more sensitive to storage temperature than to water activity. Browning in methanol-chloroform fraction was developed linearly by the progress of lipid oxidation which suggested that lipid oxidation was greatly influential to the development of browning in dried fish meat. In kinetical analysis the oxidation followed a zero order reaction mechanism as a function of carbonyl value. The activation energies obtained from the Arrhenius plot ranged 9.0 to 10.8 Kcal/mol and $Q_10$ values, 1.6-1.7. Shelf-lives at the storage of 35,45 and $55^{\circ}C$ ranged 58 days to 8 days. And in the fluctuating temperature storage at $35/55^{\circ}C$, shelf-lives were 17, 16, 15 and 13 days at 0.44, 0.52, 0.65 and $0.75\;a_w$, respectively. The shelf-lives for assessed from the accelerated shelf-life test were 125, 123, 120 and 106 days at 0.44, 0.52, 0.65 and $0.75\;a_w$, respectively, in the case of storage at $25^{\circ}C$.

• Applied Biological Chemistry
• /
• 제37권5호
• /
• pp.414-420
• /
• 1994

망간 산화물 birnessite, pyrolusite, hausmannite의 표면에서 일어나는 3가 크롬의 산화현상을 조사하였다. 이들은 zero point of charge, 표면적, 그리고 결정도 등에서 차이가 많은데, 크롬 산화현상은 모두 1차 반응이었으며 반응용액의 pH 및 최초 3가 크롬농도가 반응에 큰 영향을 미쳤다. 일반적으로 hausmannite에 의한 산화가 가장 빨랐으며 pyrolusite에 의한 산화는 상대적으로 매우 느렸다. 용액 pH와 최초 3가 크롬농도의 상호 작용이 전체 반응속도를 조절하는 것 같으며 pH가 높고 3가 크롬농도가 높을 경우 망간산화물 표면에 3가 크롬 침전되거나 complex를 형성할 수 있을 것이다. Birnessite와 hausmannite에서는 $pH\;3.0{\sim}5.0$ 범위에서 pH가 낮을수록 산화력이 높았으나 pyrolusite의 경우에는 pH가 높을수록 산화력이 증가하였다. 반응속도는 온도에 또한 민감했다. pH 3.0에서의 산화반응의 activation energies는 일반적으로 diffusion에 필요한 activation energy보다 크게 나타났으나 반응속도를 결정하는 단계가 무엇인지는 확실하지 않다.