Surface Tension Measurements by Pendant Drop Method of 10 Pure Long-Chain Alkanes and Alcohols for Temperatures up to 573.15 K

As the main components of synthetic hydrocarbons obtained using gas to liquid conversion technologies, long-chain alkanes and alcohols play an important role in the Fischer–Tropsch process. So the reliable surface tension data of these fluids are significant for the understanding and eventual improvement of synthesis efficiency. In the present study, a new high temperature and high pressure pendant drop apparatus was developed and tested with n-heptane at temperatures from (303.15 to 473.15) K, and a good agreement between the experimental data and the literature data could be found. With the new apparatus, the experimental surface tension measurements of n-dodecane, n-hexadecane, 2,2,4,4,6,8,8-heptamethylnonane, n-octacosane, squalane, 1-dodecanol, 1,12-dodecandiol, 2-butyl-1-octanol, 1-hexadecanol and 2-hexyl-1-decanol were performed under saturation conditions over the temperature range from 303.15 K (348.15 K for n-octacosane and 1-hexadecanol, 373.15 K for 1,12-dodecandiol) to 573.15 K. The combined expanded uncertainties of temperature and surface tension with a level of confidence of 0.95 (k = 2) are estimated to be 20 mK and less than 1.5% over the entire temperature, respectively. Furthermore, the surface tension data were correlated with the modified van der Waals equation, and the average absolute deviations are within 0.65%. On the basis of the correlations, the comparisons of our experimental data with the available literature data were discussed, and the satisfactory agreement revealed that the experimental results of this work were reliable and reasonable.