Oxidation curve

Fig. 1.90 Kinetic interpertation of paralinear oxidation. Curves a and b correspond to the growth of the inner compact layer and the outer porous layer, respectively curve c represents the total weight and is the algebraic sum of curves a and b. Note that as oxidation proceeds, y tends to a limiting value y, (curve a) and the overall rate of oxidation tends to a constant...

Figure 46. Separation of the overall oxidation curve into its two components a relaxation curve, responsible for the initial slope and the position of the chronoamperometric maximum, and a diffusion curve that controls the overall shape of the chronoampero-gram. (Reprinted from T. F. Otero, H.-J. Grande, and J. Rodriguez, J. Phys. Chem. 101, 3688, 1997, Figs. 1, 3, 6, 7, 13. Copyright 1997. Reprinted with permission from the American Chemical Society.)...

In order to check the survival of methanol adsorbate to the transfer conditions, the following experiment was performed. After adsorption of methanol and solution exchange with base electrolyte, the Pt electrode was transferred to the UHV chamber over a period of ca. 10 min, then back to the cell where it was reimmersed into the pure supporting electrolyte. A voltammogram was run and compared with that of an usual flow cell experiment. The results, (see Fig. 2.5a,b), show that the transfer procedure is valid. The areas under the oxidation curve are the same. As in the case of adsorbed CO on Pt (see Fig. 1.4), the change in the double peak structure indicates that some surface re-distribution may occur. 

The details of modeling the space charge distribution in oxides are presented elsewhere.249 Figure 36 presents the resulting space charge distribution in as-formed (curve 1) and aging oxides (curves... 

Fig. 31. Percentage of heat evolved, as a function of time, during the reaction of doses A, B, and C (Fig. 30) of stoichiometric mixture (CO + JO2) at the surface of a sample of gallium-doped nickel oxide (curve A in Fig. 31 corresponds to dose A in Fig. 30, etc. Reprinted from (63) with permission J. Chim. Phys. 

Figure 1 has shown that the maximum chemisorption of oxygen on chars from untreated wood occurs at HTT 450°-500°C. However, in order to understand better the effect of metal ions on the total process consisting of pyrolysis and subsequent chemisorption and oxidation of wood char, it was necessary to carry out pyrolysis, isothermal chemisorption and oxidation reactions in a single experiment. A typical overall pyrolysis, isothermal chemisorption (140°C) and oxidation curve is shown in Figure 2. The temperature program is (1) heat from 25° to 500°C at 5°C/min, (2) cool at...

Figure 1. Solid lines - cyclic voltammetric curves for hydrogen and oxygen adsorption at the three Pt single crystal planes investigated determined from the pure (CO free) 0.1 M HC10, solution. Dotted lines - cyclic voltammetric curves of adsorbed CO oxidation (note the sensitivity for the CO oxidation curves has been ten fold attenuated. Sweep rate 50 mv/s.

In both cases, the COad oxidation peaks shifted significantly to more cathodic potentials with the Pt-Ru electrode. On high area platinum without ruthenium as discussed in Copter 2, the oxidation curve was made up of two peaks, i. e. peaks for easily oxidized COad (eoCOad) and hard-to-... 

Fig. 16.18 Relationship between dissolved frac- tribution of the metal in the Fe oxide curve I lotion of various metals and dissolved fraction of cation of the metal at the Fe oxide surface curve...

The mathematical processing of co-oxidation curves can be oriented to determine, independently of any hypothesis about the recombination constants, the three relative parameters ... 

Table IV. Kinetic Parameter Values for Co-Oxidation Curves of Ethers0...

Fig. 5.6 Current-potential curves for the processes controlled by the mass transport of electroactive species. Curves 1 to 3 are for reversible processes in solutions containing (1) both Ox and Red, (2) Ox only, and (3) Red only. Curves 4 and 4 are for an irreversible reduction (curve 4) and oxidation (curve 4 ) in...

As regards the l,l-bis(acylamido)-l-deoxyalditols, the first structural study was that of Fletcher and coworkers,69 who conducted oxidations with lead tetraacetate. These authors postulated an empirical relationship between the position of the oxidation curve in a graph and the number of hydroxyl groups present. They compared the curves afforded by a series of l,l-bis(acetamido)-l-deoxyalditols with those of alditols having the same number of free hydroxyl groups, and observed a close correspondence. At present, periodate oxidation is widely applied to these mono- or di-saccharide derivatives. Under controlled conditions, the methylation technique can also be applied.42... 

Various workers (Parks 1974) have observed a correlation between the oxidation of ascorbic acid to dehydroascorbic acid and the development of an oxidized flavor. Smith and Dunkley (1962A) concluded, however, that ascorbic acid oxidation cannot be used as a criterion for lipid oxidation. Their studies showed that although ascorbic acid oxidation curves for homogenized and pasteurized milk were similar, the homogenized samples were significantly more resistant to the development of an oxidized flavor. Furthermore, whereas pasteurization caused an appreciable decrease in the rate of ascorbic acid oxidation compared to raw milk, the pasteurized samples were more susceptible to oxidation. 

Figure 7. Electrode polarization curves for oxygen-containing solutions with a mixed potential resulting from oxygen reduction accompanied by Fe2+ oxidation. Curves are schematic but in accord with available data at significant points...

Fig. 4. Electrophoretic mobilities (Ug)of natural (untreated) - curve A - and treated particles as a function of salinity (S°/°<>) for two sets of samples from Keithing Burn (KB 1 open symbols - 31 March 1982 KB 2 closed symbols - 30 dune 1982). Shaded area B indicates the spread of results from other estuaries (redrawn from Fig. 3 of Hunter and Liss 1979). Curve D - suspended particles centrifuged and resuspended in UV- oxidized sample supernatant and then UV-oxidized. Curve C - natural samples (particles plus supernatant) UV-oxidized. Curve E - sample supernatant UV-oxidized to form new particles (UV-PPT). Several UV-PPT samples from KB2 were centrifuged and the particles resuspended in their original untreated sample supernatant. The resulting changes in Ug are indicated by the dashed lines (asterisks - final values). Keithing Burn suspended matter is mostly composed of iron oxides (after Loder and Liss, 1985).

Fig. 8 Simultaneous SWV (downward curves) and ECL (upward curves) responses for (Ru-PVP/ds-CT DNA)2 films on PG electrodes in pH 5.5 buffer after incubations at 37°C with saturated styrene oxide. Curve labels are incubation times in min. (From Ref. [53] with permission. Copyright American Chemical Society.)...

It means that in reality the macroradicals are concentrated in a thin layer near the surface of polymer particles. Fig. 8 shows the temperature dependence of the rate constants of oxidation reactions for the three polymers investigated (curves b, c, d). One can see that in the temperature range investigated this dependence is in agreement with the Arrhenius equation. Let us examine the initial sections of oxidation curves. Analysis of the curves shows that they can be represented as a superposition of two different exponents corresponding to two different rate constants of radical oxidation. The temperature dependence of rate constants determined from the initial sections of oxidation curves of polymethyl-metacrylate is shown in Fig. 8 (curve a). Following fact is of interest ... 

Figure 4. Oxidation curves for JCPA-60 at temperature programming...

Fig. 7.5 also shows that S02 oxidation and gas heat up end when the heatup path reaches Fig. 7.4 s equilibrium % S02 oxidized curve. 

Because the mixed potential involves many unknown variables, it is difficult to calculate the concentration of metal ions in the slurry directly from a measurement of the mixed potential. However, relative changes in ion concentration may be inferred from changes in the mixed potential. When the Cu ion concentration increases, the reversible potential increases, shifting the entire Cu/Cu oxidation curve in the noble direction. As a result, the equilibrium with the reduction reaction shifts in the noble direction (higher potential). Thus, an increase in potential is indicative of an... 

F ure 4 5 Schematic illustration of the relationship between and [Cu. Increasing [Cu ] increases the reversible potential for copper dissolution, ec,/cu2+ shifts the Cu/Cu oxidation curve, and hence the intersection with the reduction reaction, in the noble direction. Therefore, an increase in [Cu T increases the mixed corrsion potential... 

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