Molecular-based equations of state for associating fluids: A review of SAFT and related approaches

We present a review of recent advances in the statistical associating fluid theory (SAFT). In contrast to the "chemical theory", in which nonideality is explained in terms of chemical reactions between the species, SAFT and s imilar approaches relate nonideality to the intermolecular forces involved. Such physical theories can toe tested against molecular simulations, and i mprovements to the theory can be made where needed. We describe the origina l SAFT approach and more recent modifications to it. Emphasis is placed on pointing out that SAFT is a general method and not a unique equation of sta te. Applications to a wide variety of fluids and mixtures are reviewed, inc luding aqueous mixtures and electrolytes, liquid-liquid immiscible systems, amphiphilic systems, liquid crystals, polymers, petroleum fluids, and high -pressure phase equilibria.