Initial CO2 Concentration Research Articles

Carbon Dioxide Euthanasia of Cats

SUMMARY Euthanasia of 11 adult cats and 20 kittens was carried out in a U.F.A.W. Euthanasia Cabinet and the times to loss of consciousness, respiratory arrest, and death noted. In most instances, animals were placed in a wire mesh cage and lowered to the floor of the cabinet which had been primed previously with CO2 gas. Initial CO2 concentration varied from 28 to 79 per cent with a concomitant O2 range of 15 to 4 per cent. With concentrations of CO2 greater than 60 per cent, loss of consciousness occurred within 45 seconds and respiratory arrest within 5 minutes. With lower initial concentrations of CO2 loss of consciousness occurred in 90 seconds. Respiration continued for up to 20 minutes when further CO2 was added. When animals were placed in the cabinet before CO2 was introduced, loss of consciousness did not occur for up to 150 seconds after starting the CO2 gas flow. Although a few animals showed some excitement before loss of consciousness, in no case was this either marked or prolonged. It is considered that CO2 provides a suitable alternative to chloroform for euthanasia of cats by non- veterinary personnel employed by Animal Welfare Societies.

Autoxidation of Aromatic Hydrocarbons Catalyzed with Cobaltic Acetate in Acetic Acid Solution. II. Oxidation of Ethylbenzene and Cumene

Abstract The oxidation of ethylbenzene and cumene catalyzed with cobaltic acetate in acetic acid was studied kinetically in order to elucidate the reaction mechanism and the roles of cobaltic salt. The maximum absorption rate of oxygen as well as the maximum reduction rate of Co(III) in the oxidation of ethylbenzene or cumene were of first order with respect to the initial concentration of hydrocarbon, of inverse first order with respect to the initial concentration of Co(II), and of second order with respect to the initial concentration of Co(III). The kinetic equations are therefore just the same as in the case of toluene, but d[Co(III)]/d[O2] gave a quite different average value of 3.8, showing that almost no regeneration of Co(III) from Co(II) due to oxidation with peroxidic compounds occurred. Both rates were remarkably accelerated by the addition of sodium acetate and also influenced by a small amount of water. The order of oxygen absorption rate in oxidation was toluene>ethylbenzene>cumene in contrast to the order of hydrogen abstraction rate by peroxy radicals. The apparent activation energy for these hydrocarbons was found to be 10.1 kcal mol−1.

Effect of solute concentration on the diffusivity of carbon dioxide in water

When a gas diffuses in a liquid under normal conditions, and the concentration of the diffusing gas is small, the general practice is to assume a constant diffusion coefficient. Recent work on the CO 2-water system reported that the “integral” diffusion coefficient of CO 2 decreased about 30 per cent when the initial concentration of CO 2 was increased from 0 to 60 per cent of the equilibrium value. A careful study in a liquid jet has been made of the diffusion of CO 2 in water at 25°C as a function of solute concentration to test the reported results. While a slight variation of diffusivity may have been observed, it was not statistically significant; for all practical purposes the diffusion coefficient of CO 2 in water can be considered to be constant.