AN EQUATION OF STATE FOR CARBOXYLIC-ACIDS

A cubic equation of state (CEOS) has been extended to treat systems containing carboxylic acids by taking into account association. The incorporation of chemical theory for carboxylic acids into the cubic equation of state is based on the simple and elegant approach for pure components by Heidemann and Prausnitz (1976). Using the approach of Heidemann and Prausnitz, a monomer-dimer chemical equilibrium model is built into the cubic equation of state to take care of association of carboxylic acid molecules. A closed-form equation of state, which is in terms of monomer parameters and the chemical equilibrium constant, is derived. The determination of the pure monomer parameters of an associating component is a crucial step in the application of an equation of state for associated systems. An internally consistent method is proposed to determine the pure monomer parameters for the associated component. The method reproduces the critical point and the saturated vapor pressure of the associated component accurately.