37. Muthukumaran, P.; Brinkley, R.L.; Gupta, Ram B. Lattice-fluid equation of state with hydrogen-bond cooperativity. AIChE J. (2002), 48, 386-392.

Abstract

Hydrogen bonding plays an important role in thermodn. properties of polar fluids. Existing equations of state that include h-bonding cannot accurately predict the phase behavior for polar fluids. In the theories for h-bond-chain forming mols., h-bonding strength is considered a const. at a given temp. and pressure. IR spectroscopy and ab initio calcns. show that the h-bonding strength depends on whether or not the mol. was previously h-bonded at other sites. When an h-bond is formed between an already hydrogen-bonded species and a free species, the second h-bond has different energetic characteristics from the primary h-bond. In the case of l-alkanol self-h-bonding, the equil. const. for the second h-bond is ten times that for the primary h-bond. This phenomenon called h-bond cooperativity was incorporated in a lattice-fluid-hydrogen-bonding equation of state. Calcns. for pure l-alkanols, show that the theory can be improved significantly by the incorporation of h-bond cooperativity. Agreement with the phase behavior and spectroscopic h-bonding data improves using cooperativity, without any addnl. adjustable parameters. Heat of mixing calcns. agree well with the exptl. data.

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