AN EQUATION OF STATE FOR CARBOXYLIC-ACIDS

A cubic equation of state (CEOS) has been extended to treat systems co ntaining carboxylic acids by taking into account association. The inco rporation of chemical theory for carboxylic acids into the cubic equat ion of state is based on the simple and elegant approach for pure comp onents by Heidemann and Prausnitz (1976). Using the approach of Heidem ann and Prausnitz, a monomer-dimer chemical equilibrium model is built into the cubic equation of state to take care of association of carbo xylic acid molecules. A closed-form equation of state, which is in ter ms of monomer parameters and the chemical equilibrium constant, is der ived. The determination of the pure monomer parameters of an associati ng component is a crucial step in the application of an equation of st ate for associated systems. An internally consistent method is propose d to determine the pure monomer parameters for the associated componen t. The method reproduces the critical point and the saturated vapor pr essure of the associated component accurately.