• Journal of the Korean Chemical Society
• /
• v.15 no.5
• /
• pp.219-222
• /
• 1971

The kinetics of the solvolysis of benzyl and p-or m-substituted benzyl bromides in various alcohols have been determined by an electric conductivity method. From these reactions, a curved Hammett plot is obtained and a mechanism is proposed to account for the nonlinear behavior observed. In addition, effects of solvent polarity on the activation parameters for the solvolysis of benzyl bromides are discussed.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• v.4 no.3
• /
• pp.195-200
• /
• 2000

The kinetics of the reaction between carbonyl sulfide and aqueous monoethanolamine were studied over a range of temperature (298-348 K) and amine concentrations using a wetted-sphere absorber. The key physicochemical properties used to interpret the data included the solubility and diffusivity of the COS in the aqueous amine solution. The experimental data were interpreted using a zwitterion mechanism, which produced an Arrhenius plot with third-order kinetic rate constants. The fit of these data was $K_3$=$1.32\times10(sup)10exp(\frac{-6136}{T}}$

• Bulletin of the Korean Chemical Society
• /
• v.18 no.11
• /
• pp.1199-1203
• /
• 1997

The investigation of cure kinetics of biphenyl epoxy (4,4-diglycidyloxy-3,3,5,5-tetramethyl biphenyl)-xylok resin system with four different catalysts was performed by differential scanning calorimeter using an isothermal approach. All kinetic parameters of the curing reaction including the reaction order, activation energy and rate constant were calculated and reported. The results indicate that the curing reaction of the formulations using triphenylphosphine (TPP) and 1-benzyl-2-methylimidazole (1B2MI) as a catalyst proceeds through a first order kinetic mechanism, whereas that of the formulations using diazabicyloundecene (DBU) and tetraphenyl phosphonium tetraphenyl borate (TPP-TPB) proceeds by an autocatalytic kinetic mechanism. To describe the cure reaction in the latter stage, we have used the semiempirical relationship proposed by Chern and Poehlein. By combining an nth order kinetic model or an autocatalytic model with a diffusion factor, it is possible to predict the cure kinetics of each catalytic system over the whole range of conversion.

• Journal of the Korean Chemical Society
• /
• v.16 no.5
• /
• pp.284-289
• /
• 1972

Rates of the reactions of m-and p-ring-substituted thiobenzamides with benzyl bromide in acetone have been determined by an electric conductivity method. The Hammett rule has been adopted for these reactions. It has been observed that an electron-attracting substituent accelerates the reaction while an electron-donating substituent retards the reaction, and a mechanism which accounts for the observed kinetics has been postulated. The activation energies and entropies of activation for these reactions have also been calculated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.11a
• /
• pp.163-166
• /
• 1998

The mechanism of methane sensing by Pd-SiC diode was investigated over the temperature range of 400~$600^{\circ}C$. The effects or methane gas reaction on the parameters such as barrier height, initial rate of methane gas reaction are investigated. The methane gas reaction kinetics on the device are also discussed. The physical and chemical mechanism responsible for methane detection are proposed. Analysis of steady-state reaction kinetics using I-V method confirmed that methane gas reaction processes are responsible for the barrier height change in the diode.

• Bulletin of the Korean Chemical Society
• /
• v.7 no.6
• /
• pp.462-465
• /
• 1986

Kinetics and Mechanism of $N_2H_4-KBrO_3$ reaction in the presence of allyl alcohol have been studied. The pseudo-first order rate constant for gas evolution was found to be $10^{-4}{\sim}10^{-2}\;sec^{-1}\;at\;25.0{\pm}0.1^{\circ}C$, increasing with concentration of hydrogen ion. When concentrations of sulfuric acid and allyl alcohol are both sufficiently high, the following overall reaction explains experimental results reasonably well: $N_2H_4\;+\;BrO_3^-\;+\;H^+\;{\to}\;N_2\;+\;HOBr\;+\;2H_2O,\;CH_2\;=\;CHCH_2OH\;+\;HOBr\;{\to}\;CH_2-OHCHBrCH_2OH$. More complicated reaction mechanisms at lower acidity conditions have been contemplated.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.8
• /
• pp.1887-1890
• /
• 2009

• Applied Chemistry for Engineering
• /
• v.5 no.3
• /
• pp.517-523
• /
• 1994

The effects of cure kinetics and mechanism of DGEBA(diglycidyl ether of bisphenol A)/MDA(4,4'-methylene dianiline) with SN(succinonitrile) and HQ(hydroquinone) as an additive and accelerator were investigated. Cure kinetics was evaluated by Kissinger equation and fractional-life method through DSC analysis. The activation energy has hydroxyl group as an accelerator, the activation energy and the starting cure-temperature were lower than those of DGEBA/MDA/SN system. Cure mechanism of those systems was investigated through FT-IR according to the various SN contents. The ratio was SN : HQ = 4 : 1. It has been known that the cure reactions of an epoxy-diamine system are composed of primary amine-epoxy reaction, secondary amino-epoxy reaction and epoxy-hydroxyl group reaction. But in DGEBA/MDA/SN system, primary amino-CN group reaction and CN group-hydroxyl group reaction were added to the above mentioned reactions. These reactions attributed to the long main chain and the low crossliking density. And in DGEBA/MDA/SN/HQ system, hydroxyl group of HQ formed a transition state with epoxide group and amime group and also opened the ring of the epoxide group rapidly, then amino-epoxy reaction took place easily.

• Membrane and Water Treatment
• /
• v.9 no.2
• /
• pp.95-104
• /
• 2018

Copper pollution around the world has caused serious public health problems recently. The heavy metal adsorption on traditional membranes from wastewater is limited by material properties. Different adsorptive materials are embedded in the membrane matrix and act as the adsorbent for the heavy metal. The carbonized leaf powder has been proven as an effective adsorbent material in removing aqueous Cu(II) because of its relative high specific surface area and inherent beneficial groups such as amine, carboxyl and phosphate after carbonization process. Factors affecting the adsorption of Cu(II) include: adsorbent dosage, initial Cu(II) concentration, solution pH, temperature and duration. The kinetics data fit well with the pseudo-first order kinetics and the pseudo-second order kinetics model. The thermodynamic behavior reveals the endothermic and spontaneous nature of the adsorption. The adsorption isotherm curve fits Sips model well, and the adsorption capacity was determined at 61.77 mg/g. Based on D-R model, the adsorption was predominated by the form of physical adsorption under lower temperatures, while the increased temperature motivated the form of chemical adsorption such as ion-exchange reaction. According to the analysis towards the mechanism, the chemical adsorption process occurs mainly among amine, carbonate, phosphate and copper ions or other surface adsorption. This hypothesis is confirmed by FT-IR test and XRD spectra as well as the predicted parameters calculated based on D-R model.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.1
• /
• pp.151-153
• /
• 2002