ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
This article describes a dynamic model for formation and stability of CO2-hydrate on the interface of liquid CO2(LCO2) and ocean water at large depths. Experimental results indicate that a thin film of hydrate naturally forms on the interfaces between LCO2 and water, and inhibits diffusion between the two phases. Experiments further shows that the flux of CO2 through the hydrate film is dependent of the CO2-concentration in the ambient sea water. The model proposed here explains these phenomena by introducing four major mechanisms; diffusion of water to the LCO2-phase, formation of hydrate in the LCO2-hydrate interface, decay of hydrate in the water-hydrate interface, and diffusion of CO2 through the water phase. The model explains the CO2 flux not by diffusion through the hydrate film, but suggest a mechanism of continuous hydrate formation and decay. The overall effect is a “moving,” pseudo-steady-state hydrate film due to transport of CO2 through the film. The film velocity is dependent of liquid-liquid diffusivity parameters and reaction constant, and lacking experimental values of these parameters, an order-of-magnitude analysis is done by fitting the model to experimentally obtained data for the overall film velocity. The motivation for this work is to elucidate options for CO2 depositions in deep oceans, of which liquid CO2 sequestration is believed to be one of the most feasible. Spreading of CO2 from a liquid CO2-lake and associated lowering of pH in the ecosystem surrounding the lake is of large concern. The work presented here concludes that diffusion of CO2 in the ocean is largely reduced by the hydrate film and suggests that hydrate formation may alleviate some of the environmental concerns regarding deep ocean sequestration of liquid CO2. © 1994 John Wiley & Sons, Inc.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550260207
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