Transport Process of Carbon Dioxide in Seawater and Synthetic Seawater

Abstract

Carbon dioxide (CO₂) ocean sequestration technologies, such as dissolution into seawater, are important to mitigate global warming. In this study, solution processes of CO₂ gas in seawater and synthetic seawater were experimentally and theoretically studied under various pressures and temperatures to evaluate the transport process of CO₂ in seawater. The solubilities of CO₂ in seawater and synthetic seawater were measured by a change in pressure due to absorption at temperatures ranged from 277 K to 333 K near atmospheric pressures, and ranged from 277 K to 298 K at pressures of 1 MPa, 2 MPa, and 3 MPa. It was obtained that the solubilities of CO₂ increase with an increase in pressure, but decrease with an increase in temperature. The solubility of CO₂ in synthetic seawater decreases with an increase in salt concentration. An empirical correlation for solubility of CO₂ in seawater at various temperatures and pressures was obtained based on the experimental data. In the theoretical analysis for the solution of single CO₂ bubble in seawater, the single CO₂ bubble was assumed to be stationary and surrounded by infinite liquid seawater. The rate of solution of bubble in liquid is affected strongly by various parameters, such as solubility, diffusion coefficient, bubble radius, and temperature.