Optimization of determination of CO2 gas hydrates surface tension in the presence of non-ionic surfactants and TBAC

Abstract

The gas hydrates formation, in spite of its disadvantages, has some advantages such as separating, transferring and storing gas. Therefore, determining the appropriate promoters for the gas hydrates’ formation is as important as selecting an appropriate inhibitor. One of the effective promoters is tetra-n-butyl ammonium chloride (TBAC). Due to TBAC non-destructive environmental effects and its extraordinary effect on the thermodynamics of gas hydrates, this salt is one of the most widely used promoters. TBAC was discussed in the context of hydrate structure formation and Alkyl Poly Glucoside (APG) as a nonionic surfactant, because of its characteristics like biodegradability, emulsifiers and reasonable prices. In this study, the surface tension between CO2 hydrates was determined at constant temperatures and pressures with different concentrations. For this purpose, the classical nucleation theory has been used. The experimental data show that at constant temperature, the induction time is reduced by increasing TBAC concentration and adding APG. Also, the surface tension value reduces significantly due to adding APG, which this reduction has led to an upward trend with increasing temperature. Finally, the surface tension values obtained from the developed method were compared by presented correlations.