Estimations of surface tensions at different temperatures by a corresponding-states group-contribution method

Two new equations (CSGC-ST1 and CSGC-ST2) for estimating surface tensions by applying a corresponding-states group-contribution method (CSGC) were proposed. The CSGC-ST1 equation needs only the normal boiling point data of substances to estimate accurately the surface tensions of pure substances at different temperatures. On the other hand, if the surface tension data at 20°C are available, the CSGC-ST2 equation yields estimates with higher accuracies. Group-contribution parameters for 86 groups were obtained by correlating the surface tension experimental data at different temperatures (totally 3699 datum points) of 427 pure substances including various alkanes, alkenes, cyclo-, aromatic and oxygenated hydrocarbons as well as compounds containing sulfur, nitrogen and halogen. Correlated results showed that the new models provided a wide-range of applicability and their estimation accuracies were significantly superior over the conventional corresponding-states methods currently used.