Adsorption of sodium dodecyl sulfate at THF hydrate/liquid interface

Abstract

Understanding the interaction between sodium dodecyl sulfate (SDS) and gas hydrates provides insight into the role of SDS in promoting gas hydrate formation. The aim of this study was to investigate the relationship between tetrahydrofuran (THF) hydrate induction and SDS adsorption at the hydrate/liquid interface. The adsorption behavior was studied by zeta-potential and pyrene fluorescence measurements. The negative charge of the hydrate particles remains constant at SDS concentrations of 0 to 0.17 mM. The zeta-potential becomes more negative as the SDS concentration increases from 0.17 to 3.4 mM. The micropolarity of the THF hydrate/liquid interface decreases with increasing SDS concentrations, and then it remains almost unchanged at SDS concentrations above 0.17 mM. A monolayer of DS(-) is completed at a SDS concentration of 0.17 mM. The reduction of induction time in the presence of SDS levels off at a SDS concentration of 0.17 mM. This provides strong evidence that the short induction is due to the adsorption of DS- at the hydrate/liquid interface. The adsorption study of SDS on THF hydrates can be extended to other systems and we may screen suitable surfactants for accelerating or retarding gas hydrate formation.