A Review of the Absorption and Desorption Processes of Carbon Dioxide in Water Systems

Abstract

This article is a comprehensive review of the literature dealing with the transfer of carbon dioxide to water where no chemical reactions are taking place. It reviews the studies related to the absorption and desorption kinetics, mass-transfer rates, effect of the contactor geometry, effect of water salinity, and the effects of temperature and pressure on the process in conventional reactors or the more recently common membrane contactors. The available data show inconsistent trends and an abundance of system-and geometry-specific correlations/models to predict the mass-transfer performance, which may explain the inefficient design of most industrially available contactors. Furthermore, no agreement can be found in the literature on the effect of temperature and pressure of the system, as well as the presence of additives in the water, on the solubility of CO 2 .

Absorption and desorption of carbon dioxide in several water types

“…As previously stated, CO 2 absorption/desorption has been studied using a myriad of reactor types, including but not limited to mechanically agitated tanks, bubble columns, packed‐bed absorption columns, and hollow fibre membranes . The mass transfer performance of most of these reactors/contactors is summarized in a previous work, which in turn highlighted major obstacles when comparing these studies against each other. For example, in the case of carbon dioxide absorption, various investigators reported an increase in the value of k L a with an increase in water salinity, while many others reported an opposite trend …”

“…Contradictory results are found in the literature and a consensus on a positive or negative impact has yet to be reached. This is aggravated by the fact that only a few investigators studied their effect on the absorption of CO 2 in water, rendering the need for further investigations of paramount importance …”

Effects of temperature and gas–liquid mass transfer on the operation of small electrochemical cells for the quantitative evaluation of CO2reduction electrocatalysts

“…For a 0.1 M NaHCO 3 solution at 25 1C, the solution pH should be 6.82 with a dissolved CO 2 concentration of 34.2 mM. 60 We were able to confirm this calculation by measuring a pH of 6.82 AE 0.01 for a 0.1 M NaHCO 3 solution which was allowed to equilibrate with 1 atm of CO 2 at 25 1C. Experimentally, it is convenient to make a temperature corrected pH measurement, whereas measuring the dissolved CO 2 concentration is not as readily accessible.…”

CO2 absorption into N-methyldiethanolamine aqueous-organic solvents

“…The determination of the absorbed gas flow rate was carried out in a double-wall thermostated bubble meter (5) of 10 À4 m 3 capacity, connected to the gas outlet (6) in the reactor, that allowed to operate under the required conditions. The liquid phase was loaded into a double-wall thermostated burette (7) of 2 Á 10 À4 m 3 capacity, connected to the liquid inlet of the reactor.…”

“…Alkanolamines react quickly, selectively and reversibly with CO 2 , in addition to their low volatility and reduced cost. A wide variety of alkanolamines has been studied in literature, such as the primary monoethanolamine (MEA), the secondary diethanolamine (DEA), the tertiary N-methyldiethanolamine (MDEA) or the sterically hindered 2-amino-2-methyl-2-propanol (AMP) [6,7]. The reaction kinetics will be different depending on whether the alkanolamine used is primary, secondary or tertiary, being also influenced by the aqueous or organic solvent employed.…”