Steady-state oxidation

Breiter MW. 1967. A study of the intermediates adsorbed on platinized platinum during the steady-state oxidation of methanol, formic acid and formaldehyde. J Electroanal Chem 14 407-413. 

Fig. 20. Schematic diagram showing the estimation of the time-average rate of S02 oxidation under periodic flow interruption or reduction employing steady-state oxidation rate vs liquid loading data (Figure from Haure etal., 1989, with permission, 1989, American Institute of Chemical Engineers.)...

Choi, Y.J., Chae, H.J., and Kim, E.Y., Steady-state oxidation model by horseradish peroxidase for the estimation of the non-inactivation zone in the enzymatic removal of pentachlorophenol, J. Biosci. Bioeng., 88, 368-373, 1999. 

If step III in Scheme 6 is ignored, a simplification is reached that has been demonstrated to be reasonable with certain substrates (see below). As a consequence, then the 1 catalysts should oxidize targeted reductants in accordance with Eq. (13) (here [Fe-TAML] is the total concentration of all TAML iron in solution). Eq. (13) implies that the catalysis by 1 mimics the steady-state oxidation by peroxidase enzymes, where Compound I is much more reactive than Compound II (55). 

Steady-State Oxide Thickness. The steady-state etching rate (R = S/M) does not contain any of the kinetic parameters thus it does not contain any information about the kinetics of the oxidation process. In contrast, the steady-state oxide thickness is determined by the kinetics of the transport and oxidation processes thus one can learn about these processes by studying the steady-state oxide thickness. The silicon material balance (Eq. 9)... 

HRP-catalyzed steady-state oxidation of ferrocenes by H2O2 is fun to study by UV-vis spectroscopy because ferricenium ions generated are the only absorbing species at 500-700 nm (Fig. 3). A problem, actually solved by using micellar solutions, is the limited solubility of ferrocenes in water. The kinetics of oxidation of n-alkylferrocenes (alkyl = H, Me, Et, Bu and CsHn) (119) and later of larger variety of ferrocenes shown in Chart 1 (120) via Eq. (37) has been studied in detail in micellar systems of Triton X-100, , and SDS, mostly at pH 6.0 and 25 °C. Ferrocenes with longer alkyl radicals are oxidized immeasurably slow. 

Second-Order Rate Constants for the Oxidation of Ferrocenes and Ferrocyanide by Compounds I (k6) and II (k7) and for the HRP-Catalyzed Steady-State Oxidation ( ) at [H202] 2.4 x 1 4 M (pH 6, 25 °C)... 

Thus, the conclusion from the spectroscopic investigations into the steady-state oxidation of methanol is that the surface contains a potential-dependent intermediate, single-bonded CO at less positive potentials, and bridge-bonded CO at the more positive potentials. A possible mechanism fitting the conclusion of the spectroscopy is... 

Two models were presented for the steady state oxidation of hydrogen over nickel. Both include a step for the formation of nickel oxide, one from adsorbed oxygen and the other from gaseous oxygen. The equilibrium constants for these two processes were calculated so as to discriminate between the models, the... 

The chemisorption process of methanol on clean platinum surfaces has been found to be far faster than the steady-state oxidation rate for methanol, with the result that the initial electro-oxidation current is found rapidly to decay with time. The origin of this decrease is now known to be the accumulation of adsorbed intermediates on the surface whose further oxidation to COz is slow, and the rate differences allow us to separate the... 

For the optimal efficiency to occur at steady state, oxidative phosphorylation progresses with a load. Such a load. /L is an ATP-utilizing process in the cell, such as the transport of substrates. A load, which will make the steady state the optimal efficiency state, can be identified through the total exergy loss T,c... 

These conclusions are supported by a series of related experiments on the same recombinant pea cytosolic enzyme in which the steady state oxidation of / -cresol has also been found to exhibit sigmoidal kinetics (Celik et al., 1999). In this case, the data were satisfactorily fitted to the Hill equation, Eq. (2),... 

The experimental approach was outlined in Sec. 2.3. HyperthermaJ beams of energy selected Ar atoms or N2 molecules were directed at polymer surfaces that were continously bathed with the effluent of a low pressure RF plasma source of oxygen atoms (see Fig. 7). Interaction of the effusive 0-atom beam with polymer samples produced both CO and CO 2 continuously, and data were collected under conditions of steady-state oxidation, as verified by the unchanging signals from CO and CO2 in the mass spectrometer. Product TOF distributions were collected at m/z = 28(CO+) and 44(002 ), following impingement of hyperthermaJ beam pulses on polymer surfaces that had reached a steady state of oxidation. 

The first step in the experimental procedure consists of preparative electrolysis of the aromatic compound A to A . The preparative potentiostat is then disconnected and a UME is inserted into the cathodic compartment. The steady-state oxidation current of A is recorded as a function of time for a certain time period to ascertain that the stability of A is high. If this is indeed the case, the alkyl halide RX is added to the solution while it is stirred for a few seconds to assure that homogeneous conditions apply for the reaction of Eq. 90. The recorded current is observed to decay exponentially towards zero. A plot of In / versus t is shown in Figure 16 for four different combinations of aromatic compounds and sterically hindered alkyl halides. From the slopes of the straight lines, -2A etCrx, A et values can readily be obtained. The method is useful for the study of relatively slow reactions with kET < 10 M- s-. ... 

Figure 16. Current decay curves the natural logarithm of the steady-state oxidation plateau current of radical anions (mediators) plotted against time (s) for the following four combinations of mediator/substrate benzophenone/l-bromo-2,2-dimethylpropane (-(-) perylene/l-bromo-2,2-dimethylpropane (x) perylene/l-bromoadamantane ( ) and quinoxaline/2-chloro-2-methyl-propane (O). All measurements were obtained with a 10-pm platinum disk electrode in DMF/0.1 M BU4NBF4 at 22°C. From S. U. Pedersen and K. Daasbjerg, Acta Chem. Scand, 43 30 (1989) [36],...

Zhdan et al. ° have found an unreactive form of O on Ir(l 11) even at 1100 K, and have gone on to study the steady-state oxidation on this surface, establishing a Langmuir-Hinshelwood mechanism for reaction between chemisorbed O and chemisorbed CO. Two forms of adsorbed O on Ir(lll) have also been identified by Ivanov et al., only one of which is active in CO oxidation. 

The Steady State Oxidation States of the Metals and Reduction in the Formation of Carbon Oxides (CO,... 

Another explanation was the following. The organomontmorillonite used was a natural montmorillonite that contained iron. Chemical analysis of the clay confirmed the presence of a low amount of iron. It was recalled that iron and, in more general terms, metals are likely to induce the photochemical degradation of polymers. Iron at low concentration had a prooxidant effect that was due to the metal ion of iron that can initiate the oxidation of the polymer by the well-known redox reactions with hydroperoxides [93]. It was concluded that the transition metal ions, such as Fe, displayed a strong catalytic effect by redox catalysis of hydroperoxide decomposition, which was probably the most usual mechanism of filler accelerating effect on polymer oxidation. A characteristic of such catalytic effect was that it did not influence the steady-state oxidation rate, but it shortened the induction time. 

The lattice gas model with this approximation was used for the description of the reaction of gases on metal surfaces. Among the studied reactions was the steady state oxidation of CO over Ir, hydrogen over Pt, the kinetics of the CO - NO and CO-O2 reactions over Rh and Pt, showing a complex dynamic behavior. 

Fig. 3. Concentration profile inside the reactor without flow reversal (alternative 1) for hydrogen in the oxidation step (a) at the end of each period during the transient and (b) in the periodic steady state (oxidation 0.-5

Figure 13. Variation of A and with potential in steady state and transient (x, 0.8 0, 0.32 A, 0.08 mA crn ) oxidation and i—V relation in steady state oxidation. (9,0)Galvanostatic oxidation transients potentiostatic steady state) oxi-...

Fleischmann, M., Mansfield, J.R. and Wynne-Jones, W.K.F. (1965) The anodic oxidation of acetate ions at smooth Pt electrodes. Part 1. The non-steady state oxidation of Pt. Journal of Electroanalytical Chemistry, 10,511. 

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