• Bulletin of the Korean Chemical Society
• /
• v.30 no.6
• /
• pp.1341-1348
• /
• 2009

Electrocatalytic oxidation of two anti-inflammatory drugs (Mefenamic acid and Indomethacin) was investigated on a cobalt hydroxide modified glassy carbon (CHM-GC) electrode in alkaline solution. The process of oxidation and its kinetics were established by using cyclic voltammetry and chronoamperometry techniques as well as steady state polarization measurements. Voltammetric studies indicated that in the presence of under study drugs, the anodic peak current of low-valence cobalt species increased, followed by a decrease in the corresponding cathodic current. This result indicates that the drugs were oxidized via cobalt hydroxide species immobilized on the electrode surface via an E$\acute{C}$ mechanism. A mechanism based on the electrochemical generation of Co (IV) active sites and their subsequent consumption by the drugs in question was also investigated. The constants rate of the catalytic oxidation of the drugs and the electron-transfer coefficients reported.

• Journal of environmental and Sanitary engineering
• /
• v.15 no.3
• /
• pp.88-93
• /
• 2000

The objective of this study was to depict the kinetic behavior of the platinum catalyst for the deep oxidation of VOCs and their mixture. The oxidation characteristics of VOCs, which were benzene, toluene, and styrene, was studies on a 0.5% $Pt/{\gamma}-Al_2O_3$ catalyst. The reactivity increases in order benzene>toluene>styrene. In mixtures, remarkable effects on reaction rate and selectivity have been evident ; the strongest inhibiting effect was shown by styrene and increases in a reverse order with respect to that of reactivity. The reaction model reveals that there is a competition between the two reactants for the oxidized catalyst. Thus, the nontoxic catalytic oxidation process was suggested as the new VOCs control technology.

• Korean Chemical Engineering Research
• /
• v.54 no.3
• /
• pp.340-349
• /
• 2016

Electro oxidation system was designed in this study for the reduction of COD (Chemical Oxygen Demand) from high-strength wastewater, produced during refinery turnaround period. First, BDD (Boron Doped Diamond) electrode was synthesized and electro oxidation system of actual industrial wastewater was developed by adopting the synthesized BDD electrode. The experiments were carried out under various operating conditions under certain range of current density, pH, electrolyte concentration and reaction time. Secondly, reaction kinetics were identified based on the experimental results, and the kinetics were embedded into a genetic mathematical model of the electro oxidation system. Lastly, design and operating parameters of the process were optimized to maximize the efficiency of the pretreatment system. The coefficient of determination ($R^2$) of the model was found to be 0.982, and it proved high accuracy of the model compared with experimental results.

• Polymer(Korea)
• /
• v.24 no.2
• /
• pp.252-258
• /
• 2000

Various crosslinked poly(4-vinylpyridines) (CHP4VP) having different degrees of crosslinking were synthesized by radical copolymerization of 4-vinylpyridine with if N,N' -1, 6-hexamethylenebisacrylamide, and CHP4VP- Cu(II) complexes were prepared by the method of adsorption equilibrium. The catalytic activity of the complexes for the oxidation of ascorbic acid (AA) was investigated. The oxidation of AA by these complexes showed a kinetic behavior of the Michaelis-Menten type. The catalytic activity of CHP4VP-Cu(I ) catalytic system was increased with increasing the degree of crosslinking of CHP4VP, and its activity was scarcely decreased even after repeated use. However, the tendency of the catalytic activity of CHP4VP-Cu(II) complexes was decreased for the oxidation of AA when compared with that of the previously reported catalytic system containing crosslinked poly(4-vinylpyridine) prepared using N,N'-methylenebisacrylamide as a crosslinker. These results indicate that the degree of crosslinking of CHP4VP and the hydrophobicity of the crosslinker play an important role in the catalytic system of the oxidation of AA.

• Journal of Electrochemical Science and Technology
• /
• v.13 no.2
• /
• pp.292-307
• /
• 2022

The study presents kinetics of degradation and mineralization of an anti-epileptic drug Lamotrigine (LAM) in the aqueous matrix by electrochemical advanced oxidation process (EAOP) on Ti/DSA (Ta₂O₅-Ir₂O₅) and Stainless Steel (SS) anodes using sodium sulphate as supporting electrolyte. On both the anodes, kinetic behaviour was pseudo-first-order for degradation as well as mineralization of LAM. On Ti/DSA anode, maximum LAM degradation of 75.42% was observed at an associated specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm² and 100 ppm Na₂SO₄ concentration. Maximum mineralization attained was 44.83% at an associated specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm² and 50 ppm concentration of Na₂SO₄ with energy consumption of 2942.71 kWh/kgTOC. Under identical conditions on SS anode, a maximum of 98.92% LAM degradation was marked after a specific charge (Q) of 3.1 (Ah/litre) at a current density of 1.38 mA/cm² and 100 ppm concentration of Na₂SO₄. Maximum LAM mineralization on SS anode was 98.53%, marked at a specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm² and 75 ppm concentration of Na₂SO₄, with energy consumption of 1312.17 kWh/kgTOC. Higher Mineralization Current Efficiency (MCE) values were attained for EAOP on SS anode for both degradation and mineralization due to occurrence of combined electro-oxidation and electro-coagulation process in comparison to EAOP on Ti/DSA anode due to occurrence of lone electro-oxidation process.

• Journal of the Korean Chemical Society
• /
• v.27 no.3
• /
• pp.183-188
• /
• 1983

The catalytic oxidation of $SO_2$ has been investigated in the presence of vacuum-activated 10 mol % Ni-doped ${\alpha}-Fe_2O_3$ under various partial pressures of $SO_2\;and\;O_2$ at temperatures from 320 to $440{\circ}C$. Over the temperature range $320{\sim}440{\circ}C$, the activation energy is 13.8 $kcal{\cdot}mol^{-1}$. The oxidation rates have been correlated with 1.5 order kinetics; first order with respect to $SO_2$ and 0.5 order with respect to $O_2$. From the kinetic data and conductivity measurements, the adsorption, oxidation mechanism of $SO_2$ and the defect structure of vacuum-activated 10 mol % Ni-doped {\alpha}-Fe_2O_3$ are suggested. $O_2\;and\;SO_2$ appear to be adsorbed essentially as ionic species. Two surface sites, probably an $O^{2-}$ lattice and an oxygen vacancy which is induced by Ni-doping, might be required to adsorb $SO_2\;and\;O_2$. The conductivity measurements and kinetic data indicate that the adsorption process of $SO_2\;{(SO_2+O^{2-}}_{(latt)}{\rightleftharpoons}{{SO_3}^-}_{(ads)}+e')$ is the rate-determining step.

• Journal of the Korean Chemical Society
• /
• v.30 no.2
• /
• pp.231-236
• /
• 1986

Oxidation of $[Mo_2O_4(C_2O_4)_2(OH_2)_2]^{2-}$ with hydrogen chromate yields the molybdenum (VI) complex, $[Mo_2O_4(C_2O_4)_2(OH_2)_2]^{2-}$. Stoichiometry for the reaction of $[Mo_2O_4(C_2O_4)_2(OH_2)_2]^{2-}$ with hydrogen chromate are expressed as ${3Mo_2}^V+2Cr^{VI}\;{\rightleftharpoons}\;{3Mo_2}_{VI}+2Cr^{III}$. Observed rate constants are dependent on $[H+]^2$. The kinetic data are consistent with a mechanism in which three successive single-electron steps convert $Cr^{VI}$to $Cr^{III}$ by way of intermediate Cr^V$ and $Cr^{IV}$. Mechanism of the reaction are presented and discussed.

• Journal of the Korean Chemical Society
• /
• v.30 no.1
• /
• pp.57-62
• /
• 1986

Oxidation of $[Mo_3O_4(C_2O_4)_3(H_2O)_3]^{2-}$ with HCr$O_4^-$ yields the molybdenum(Ⅳ) complex, $[Mo_2O_5(C_2O_4)_2(H_2O)_2]^{2-}$. Stoichiometry for the reaction of $[Mo_3O_4(C_2O_4)_3(H_2O)_3]^{2-}$ with HCr$O_4^-$ are expressed as $2Mo_3^{IV} + 4Cr^{VI} {\to} 3Mo_2^{VI} + 4Cr^{III}$. Observed rate constants are dependent on hydrogen ion concentration. The kinetic data are consistent with a mechanism in which three successive single-electron steps convert $Cr^{VI}$to $Cr^{III}$ by way of intermediate $Cr^V$ and $Cr^{IV}$. Detailed mechanisms are presented and discussed.

• Journal of the Korean Chemical Society
• /
• v.29 no.2
• /
• pp.111-120
• /
• 1985

The oxidation reaction of CO on the catalysts 4 mol%, 8 mol%, and 12 mol% Cd-doped ${\alpha}-Fe_2O_3$ is individually investigated. Regardless of Cd doping level, over-all reaction order for the oxidation of CO is 1.5; the first order with respect to CO and the one-half order with respect to $O_2$. Over the temperature range of 350∼$460^{\circ}C$, the activation energy for CO oxidation is 10.10∼11.30Kcal/mol. From the agreement between the kinetic data and conductivity measurements, the reaction mechanism is suggested. Especially from the effect of Cd doping, the fact that catalytic activity of ${\alpha}-Fe_2O_3$ is due to the excitation of electrons which are traped on oxygen vacancy is found, and the adsorption sites for reactant molecules are found.

• Journal of the Korean Chemical Society
• /
• v.57 no.6
• /
• pp.703-711
• /
• 2013

In the present investigation, kinetic studies of oxidation of formic acid with and without catalyst and promoter in aqueous acid media were studied under the pseudo-first order conditions [formic acid]T ${\gg}[Cr(VI)]_T$ at room temperature. In the 1,10-phenanthroline (phen) promoted path, the cationic Cr(VI) phen complex is the main active oxidant species undergoes a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition through several steps leading to the products $CO_2$ and $H_2$ along with the Cr(III) phen complex. The anionic surfactant (i.e., sodium dodecyl sulfate, SDS) and neutral surfactant (i.e., Triton X-100, TX-100) act as catalyst and the reaction undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Whereas the cationic surfactant (i.e., N-cetyl pyridinium chloride, CPC) acts as an inhibitor restricts the reaction to aqueous phase. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. The neutral surfactant TX-100 has been observed as the suitable micellar catalyst for the phen promoted chromic acid oxidation of formic acid.