Oxygen absorption rates

Probably an important pro-oxidant for all mbbers is ultraviolet (UV) hght. Blake and Bmce [ 17] performed a study of the oxygen absorption rates of unvulcanized NR mbbers under exposure to UV light. It was observed that exposure to light caused dramatic increases in the oxygen absorption... 

Second, the energy of emission activation is close to the energy of activation of adsorption of oxygen by silver - 146 kj/mol [49]. This implies that emission of O-atoms occurs due to energy of defect annihilation in the surface-adjacent layers of catalyst due to adsorption of oxygen. From the stand-point of such assumption it is obvious that depletion of emission is linked with sloroing down of the oxygen absorption rate (as shown, for instance, in Fig. 6.12). 

Oxygen Absorption Rate - The Effect of a Dispersed Organic Phase... 

In order to estimate the real effect of a dispersed organic phase on the productivity of fermentation, the oxygen absorption rate has to be defined. Knowing its mathematical expression, the rate equation can then be incorporated into the differential mass balance equations of fermentation and, after solving these equations, the concentration of components in a fermentation... 

As previously discussed, the oxygen absorption rate can essentially be increased using a dispersed organic phase with higher solubility and/or diffusivity. The... 

The relations of molar extinction coefficients and oxygen absorption rates, plotted vs. time, are illustrated in Figures 3 and 4 (solvents, benzene and butyric acid, respectively). The variation of coefficients was parallel to the rate of oxygen absorption—i.e. the larger the coefficient, the higher the oxygen absorption rate. It is considered therefore that the catalyst at its maximum absorption coefficient is in a desirable form for oxidizing acrolein. 

Fig. 24. Relationship between partial pressure of oxygen and oxygen absorption rate by poly(L-lysine)-heme complex (a) and equilibrium curve for CO binding by poly(L-lysine)-heme complex (b)107,108)...

Wasserman, A. E. and Hampson, J. W. 1960. Whey utilization. III. Oxygen absorption rates and the growth of Saccharomyces fragilis in severed propagators. AppL Microbiol. 8, 293-297. 

The oxygen absorption rate per unit volume qj v can be estimated by... 

Since the oxygen is sparingly soluble gas, the overall mass-transfer coefficient KL is equal to the individual mass-transfer coefficient KL. Our objective in fermenter design is to maximize the oxygen transfer rate with the minimum power consumption necessary to agitate the fluid, and also minimum air flow rate. To maximize the oxygen absorption rate, we have to maximize KL, a, C - CL. However, the concentration difference is quite limited for us to control because the value of C L is limited by its very low maximum solubility. Therefore, the main parameters of interest in design are the mass-transfer coefficient and the mterfacial area. 

Yoshida F., Ikeda A., Imakawa S., Miura Y, Oxygen Absorption Rates in Stirred Gas-liquid Contactors, Ind. Eng. Chem. 52 (1960) 5,... 

The oxygen absorption rates were measured in an apparatus essentially the same as that used previously by the author. The temperature at which the measurements were carried out was 110° = = 0.1° and the reaction mixtures were stirred at the rate of 1200 = = 15 r. p. m. 

Table 2 shows the effect of anthraquinone on the maximum oxygen absorption rate of anethol. This effect can be shown more clearly in figure 1 in which the V has been plotted against time. All the values of V have been calculated to N. T. P. 

Kppect op Anthraquinone on the Maximum Oxygen Absorption Rate op Anethol... 

In a previous article, the author has briefly pointed out the importance of the maximum oxygen absorption rate. Subsequent work has shown that its value is one of the most significant properties in all auto-oxidation measurements. Its importance has been overlooked by previous investigators. Its position with respect to the two axes seems to determine the purity of the substance to be oxidized. If several experiments are carried out under similar conditions, this maximum remains, within experimental error, always the same with the same substance, and it is very characteristic with each individual substance. If one now adds a small quantity of a foreign substance, the position of this maximum is changed and there... 

An equation has been derived showing a simple quantitative relationship between the maximum oxygen absorption rate, the concentration of the catalyst and the time necessary for the oxidation rate to attain a maximum value. This equation holds for measurements made with... 

The importance of the maximum oxygen absorption rate has been emphasized as one of the most characteristic properties in all auto-oxidation phenomena. 

This value corresponds to oxygen absorption rates which have been measured in shaken flasks and fermenters under optimum conditions. In our fermenters, a maximum oxygen absorption rate of 250 mmoles 02/hour/l was achieved when a strong stream of air was supplied and the solution was stirred at 2000 r.p.m. The determination of the oxygen transfer rates was made by the sulfite oxidation method. 

Although absorption plus chemical reaction sounds more complex than physical absorption or desorption, the absorption of oxygen in sulfite solutions is often used to characterize the performance of bubble columns or stirred reactors. With a 0.2-1.0 N solution of sodium sulfite and a small amount of copper sulfate as catalyst (10 M), the rate of oxidation is independent of sulfite concentration, and the oxygen absorption rate is constant until nearly all the sulfite has reacted ... 

Calculate the oxygen absorption rate in Ib-mol/hr-ft (of reactor cross section), allowing for the ehange in molar flow rate of the gas. 

A partial oxidation is carried out by bubbling oxygen through a solution of reactant B in a stirred reactor. Batch tests show the oxygen absorption rate decreases as the conversion of B increases (Table 7.4). The initial reaction rate divided by the oxygen solubility is less than the value predicted from correlations for though the predicted rate is uncertain by 30%. 

Thermogravimctric Analy.sis (TGA) weight I0S.S on heating thermo-oxidative stability, oxygen absorption rate... 

The oxidation process takes place once a fresh coal surface is exposed to air however, the oxygen absorption rate is inversely proportional to time if the temperature remains constant. Therefore, if the coal is stockpiled so that the temperature in the pile does not rise appreciably insofar as the heat is removed at least as fast as it is generated by the oxidation process, the oxidation rate and, thus, the deterioration or weathering rate of the coal will lessen with time (Vaughn and Nichols, 1985). 

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