Adsorption Isotherm of Sodium Dodecyl Sulfate In Hydrate Particles

Sodium dodecyl sulfate (SDS) has been known to accelerate gas hydrate formation. One possible mechanism proposed that SDS forms micelles in bulk water phase and the hydrophobic environment inside the micelles accommodates non-polar guest molecules such as methane, ethane, propane, etc. so the fast nucleation may be induced by having better contact between water and guest molecules [1]. However, recent studies [2-4] reported that SDS does not form micelles if the gas hydrate formation temperature is below the normal Krafft point (281-289 K) for SDS. We proposed [5] that SDS reduces the energy barrier of hydrate nucleation by adsorbing onto hydrate nucleus surface. We will characterize the SDS adsorption onto the CP hydrates using zeta-potential measurements and will present the SDS isotherm with particle size distribution of gas hydrates.

(1) Zhong, Y.; Rogers, R. E. Surfactant effects on gas hydrate formation. Chem. Eng. Sci. 2000, 55, 4175-4187.

(2) Watanabe, K.; Niwa, S.; Mori, Y. H. Surface tensions of aqueous solutions of sodium alkyl sulfates in contact with methane under hydrate-forming conditions. J. Chem. Eng. Data 2005, 50, 1672-1676.

(3) Di Profio, P.; Arca, S.; Germani, R.; Savelli, G. Surface promoting effects on clathrate hydrate formation: Are micelles really involved? Chem. Eng. Sci. 2005, 60, 4141-4145.

(4) Zhang, J. S.; Lee, S. Y.; Lee, J. W. Does SDS micellize under methane hydrate-forming conditions below the normal ambient Krafft point? J. Colloid Interface Sci. 2007, 315, 313-318.

(5) Zhang, J. S.; Lee, S. Y.; Lee, J. W. Kinetics of methane hydrate formation from SDS solution. Ind. Eng. Chem. Res. 2007, 46, 6353-6359.