Surface tension prediction for pure fluids

Abstract

Abstract For the surface tension of organic compounds, σ = [ 𝒫·(ρ l ‐ ρ v )] 4 is proposed where 𝒫 = 𝒫 0 ·(1 − T r ) 0.37 ·T r ·exp(0.30066/T r + 0.86442·T ). ρ l and ρ v are molar densities of liquid and vapor, respectively, T r = T/T c , and 𝒫 0 is a temperature‐independent, compound‐dependent constant similar to Sugden's parachor. This new expression, derived from statistical‐mechanics, represents the experimental surface tension data of 94 different organic compounds within 1.05 AAD%. We also propose 𝒫 0 = 39.6431· [0.22217 − 2.91042 × 10 −3 ·(ℛ*/T )·T /P ] as a corresponding‐states expression to correlate the temperature‐independent parameter 𝒫 0 for various compounds. Here, ℛ* = ℛ m,ref , ℛ m is the molar refraction, ℛ m,ref is the molar refraction of the reference fluid (methane), and T br is the reduced normal boiling point. When this generalized expression is used, surface tensions for all 94 compounds can be predicted within 2.57 AAD% at all temperatures investigated.