Oxygen transfer number

Figure 3.26. Typical plot of data showing the relation between oxygen transfer number ATotr versus modified dimensionless power number at different conditions. (Adapted from Zlokarnik, 1979).

Figure 3.27. Typical plot of data of surface aerator efficiencies expressed as modified oxygen transfer number versus Froude number iVpr. The shaded area includes the range of different tested types. (Adapted from Zlokamik, 1979.)...

Thus, we measure formation rate in air, pure oxygen gas and then in an inert gas. If the rates do not differ significantly, then we can rule out gaseous transport mechanisms. There are other tests we can apply, including electriccd conductivity, transference numbers and thermal expcmsion. Although these subjects have been investigated in detail, we shall not present them here. 

Interestingly, the nonpolyether-type polymer electrolyte 7 showed a relatively high lithium transference number of 0.47 in the presence of LiTFSI. This is possibly due to the absence of strong binding of ether oxygen to the lithium cation. Moreover, anion trapping of the boron atom is not retarded by coordination of oxygen to the... 

A number of approaches to the air-water mass transport exist. In relation to transport processes in sewer networks, the main developments have been directed toward the air-water oxygen transfer. The following are the main theoretical descriptions that are relevant in this respect ... 

The value of the overall oxygen transfer coefficient, KLa = KLC>2, is central for the determination of the rate of oxygen transfer, F. Table 4.7 summarizes a number of empirical expressions proposed for the determination of K,a in gravity sewers (Jensen, 1994). 

Despite of the common reaction mechanism, peroxo complexes exhibit very different reactivities - as shown by the calculated activation energies -depending on the particular structure (nature of the metal center, peroxo or hydroperoxo functionalities, type and number of ligands). We proposed a model [72, 80] that is able to qualitatively rationalize differences in the epoxidation activities of a series of structurally similar TM peroxo compounds CH3Re(02)20-L with various Lewis base ligands L. In this model the calculated activation barriers of direct oxygen transfer from a peroxo group... 

The development of the mass burning rate [Eq. (6.118)] in terms of the transfer number B [Eq. (6.120)] was made with the assumption that no oxygen reaches the fuel surface and no fuel reaches °°, the ambient atmosphere. In essence, the only assumption made was that the chemical reactions in the gas-phase flame zone were fast enough so that the conditions mos = 0 = m[m could be met. The beauty of the transfer number approach, given that the kinetics are finite but faster than diffusion and the Lewis number is equal to 1, is its great simplicity compared to other endeavors [20, 21],... 

This situation, as discussed in the last section, closely resembles that of the droplet diffusion flame, in which the oxygen concentration approaches zero at the flame front. Now, however, the flame front is at the particle surface and there is no fuel volatility. Of course, the droplet flame discussed earlier had a specified spherical geometry and was in a quiescent atmosphere. Thus, hD must contain the transfer number term because the surface regresses and the carbon oxide formed will diffuse away from the surface. For the diffusion-controlled case, however, one need not proceed through the conductance hD, as the system developed earlier is superior. 

One last point. In the reaction of uranium(IV) where it is convenient to do a tracer experiment because there is only one metal ion product, we have actually determined the number of oxygens transferred to the uranyl ion product from the chlorite, and this number corresponds to 1.3 oxygen per chlorite transferred to the uranium. This is consistent with the results we reported some years ago (5) on the oxidation of uranium (IV) with Pb02 and Mn02, where indeed more than one oxygen is transferred. In conclusion, we feel that we have some direct evidence for two-electron transfer in these reactions and the formation of a chlorine(I) intermediate followed by the formation of chlorate. 

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