Document Type : Research Paper


1 Ph.D. Candidate, Petroleum University of Technology Ahwaz, Iran

2 Professor, Department of Gas Engineering, Petroleum University of Technology, Ahwaz, Iran


A device is designed and constructed for measuring the equilibrium surface tension of water and a number of other solutions. The measured equilibrium surface tension of water, as a reference fluid, has good consistency with literature data. Moreover, the equilibrium surface tension of the aqueous solutions of surfactants and polymer composed of sodium dodecyl sulphate (SDS), Triton CG-110, dimethyl di-dodecyl-ammonium bromide (DDAB), and polyethylene glycol (PEG) with different molecular weights of 200, 300, 400, and 600, as well as that of the ternary solutions of SDS/PEG/water, Triton CG-110/PEG/water, and DDAB/PEG/water at 293.15 K and atmospheric pressure are measured. The equilibrium surface tension of the aqueous solutions of PEG 600 are measured at 296.15 K because PEG 600 is solid at 293.15 K. The measured data are compared with the predictions of thermodynamic models, and the results show that Redlich-Kister (RK) model has the lowest error in predicting the experimental data.


  • An experimental setup for measuring equilibrium surface tension of solutions is designed and constructed.
  • To show the reliability of the experimental setup, some data on pure water are measured and compared with the literature data, and good consistency is observed.
  • The equilibrium surface tension of aqueous solutions of different surfactants (sodium dodecyl sulphate (SDS), Triton CG-110, dimethyl di-dodecyl-ammonium bromide (DDAB)) and polyethylene glycol with molecular weights of 200, 300, 400, and 600 and the equilibrium surface tension of ternary solutions of PEG–surfactant–water have been measured and reported.
  • Redlich–Kister (RK) thermodynamic surface tension model has the lowest error in predicting the experimental data.


Main Subjects

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