Viscosity modeling of water + alkanediols mixtures

In this study, both theoretical and empirical viscosity models were evaluated for binary associating liquid mixtures of water + 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol. The interaction between molecules in the mixtures was analyzed using the calculation of excess energy of flow obtained from Eyring's absolute rate theory. Free volume (FV) viscosity model was coupled with Peng-Robinson (PR) and perturbed-chain statistical associating fluid theory (PC-SAFT) equation of states (EoS); friction theory (FT) was coupled with PR EoS; no significant difference was observed in the modeling results using different EoS. A new mixing rule was found to improve the modeling results of FT coupled with the PR EoS for the binary mixtures studied. The empirical models correlated viscosity of aqueous diol systems well with average absolute percent deviation (AAD%) < 1.