Dissolution Rate Of CO2 Research Articles

ＣＯ２液滴の水または海水に対する溶解挙動の観察

Sequestration of liquid CO2 into intermediate depth ocean has been considered as a means to reduce atmospheric concentration of this greenhouse gas and to mitigate global warming. The dissolution behavior of CO2 into pure/sea water was investigated under conditions in the intermediate ocean, that is, high pressure and low temperature. In these conditions, the CO2 clathrate hydrate film was formed at the interface between CO 2, and (sea) water. The hydrate film has been considered to affect and decrease the dissolution rate.In the experiments, LIF technique was used. LIF intensity showed pH of CO2 dissolved water. Therefore, we could know the dissolution rate of CO2 and the non-uniform two dimensional CO2 concentration distribution during the CO2 dissolution with or without the hydrate film in pure/sea water.The dissolution rate was faster in pure water than in sea water. The dissolution rate with the hydrate became about half of that without hydrate both in case of pure/sea water.

Study of the (electro)chemical equilibria in molten carbonate under MCFC cathode gas conditions. Part II: non-equilibrium study of (electro)chemical reactions involved in oxygen reduction in molten carbonate

Assuming fast CO2 dissolution into the melt, the recombination reaction rate of O2− with CO2 was determined at 8.1±0.1×10−2 atm−1 s−1 with oxide addition experiments. This is a few times higher than the value of 1.7×10−2 atm−1 s−1 determined by Lu and Selman using the same experimental method [1]. Both values are six orders of magnitude smaller than the value of 7.6×104 atm−1 s−1 obtained by Nishina et al. from CV measurements [2]. A slow CO2 dissolution rate, though unlikely, was discussed as possible explanation for this discrepancy. For the fast and slow recombination reaction rates an acidic and basic melt was calculated respectively in the cathode in an operating MCFC. It was found here that the predominant reduced oxygen species in molten Li/K carbonates changes from peroxide in basic melts to probably superoxide in acidic melts, which is in accordance with most of the recent literature 2, 3, 4, 5, 6, 7, 8, 9, 10. In the former case effects from autocatalytic reactions on the performance of the MCFC cathode as suggested by Adanuvor et al. are likely [11]. Non-equilibrium experiments showed that the cyclic voltammetry (CV) response of the reversible reduction of O22−toO2−in basic melts is characterised by the para meter γ=cO2−DO2−/cO2−2DO2−2 which was determined here at γ=2.9±0.2/pO2 atm−1/2. The equi librium constants for 12O2+O2−⇔O2−2 and CO2−3⇔CO2+O2− were determined at 0.55±0.2 atm−1/2 and 1.5×10−8 atm respectively. The diffusion constant of peroxide at 4±2×10−6 cm2 s−1. These values are in reasonable accordance with literature data 7, 8, 12.

Kinetics on the dissolution of CO2 into water from the surface of CO2 hydrate at high pressure

AbstractKinetic study on the dissolution of CO2 from the surface of a liquid CO2 droplet in water was conducted, and a mechanism of the decay of CO2 hydrate was proposed. The model was applied to the experimental data which showed that the radius of liquid CO2 droplets in water reduced linearly with time. It was proved that the dissolution rate of CO2 into water is dominated by the decay of CO2 hydrate on the surface of the droplet. The rate constant of the decay of CO2 hydrate was estimated to be 1.25 × 10−6 m s−1. From a viewpoint of liquid CO2 disposal in the deep ocean, it is predicted that the thin membrane of CO2 hydrate at the interface between seawater and liquid CO2 will control the dissolution of CO2 into seawater. © 1995 John Wiley & Sons, Inc.