TABLE OF CONTENTS JUSTIN SALMINEN [1] , [2] AND JOHN PRAUSNITZ [1] , [3]
Carbon dioxide as a useful reactive ingredient has increasingly gained interest in several process industries. These include buffered carbonate and alkaline systems that depend on the solubility and reactivity of the reactants. CO 2 gas is commonly used for pH control that facilitates dissolution and precipitation of carbonates.1 8 Techniques for removing acid gases like CO 2 and H 2S from flue gases by absorption are commonly used in coal gasification and sweetening of natural gases.9 ,10 Aqueous alkanolamine is often used for absorption. These well-studied systems include aqueous mixtures of monoethanolamine (MEA), n-methyldiethanolamine (MDEA), diethanolamine (DEA), and 2-amino-2-methyl-1-propanol (AMP).5 ,10 52 Ionic liquids have recently been studied for CO 2 absorption and other industrial applications.53 67 For process design, we require knowledge of molecular interactions, speciation, and solubilities as well as chemical equilibria in reactive multiphase systems. At specified temperature and liquid composition, the total pressure of the system is mainly determined by the concentration of non-dissociated dissolved CO 2 (aq) according to Henry s law. As discussed later, the non-dissociated CO 2 (aq) is in equilibrium with ionic bicarbonate, carbonate and other ionic species in the system, and with solid phases. Modeling of both phase equilibia and chemical equilibria provides a rigorous tool for describing aqueous industrial and environmental processes that contain CO 2.8 10 ,14 ,
