Kinetic study of carbon dioxide hydrate formation by thermal analysis in the presence of two surfactants: Sodium dodecyl sulfate (SDS) and lauryl alcohol ethoxylate (LAE)

Abstract

In the present study, formation kinetics of carbon dioxide hydrate has been investigated by thermal analysis. Since differential scanning calorimetry has no agitation, a small amount of two surfactants of sodium dodecyl sulfate (SDS) and lauryl alcohol ethoxylate (LAE) has been used to improve gas/aqueous solution interface and increase gas diffusion into the solution. A central composite design of experiment has evaluated the hydrate formation kinetics aiming to maximize the heat ratio and heat flow rate, while minimizing of the relaxation time is desirable. The optimal values of CO2 hydrate formation has been found to be at gas pressure of 3.045MPa and surfactant concentration of 29ppm in the presence of LAE2. It is clear that the kinetics of hydrate formation is promoted at higher pressure. The driving force is the key component of a hydrate nucleation and growth. On the other hand, LAE2 leads to a more increased the kinetics hydrate formation because it can represent lower gas-liquid interfacial tension than SDS. Moreover, the surfactant concentration considerably affected the kinetics hydrate formation after CMC value of surfactants. That means the formation of surface micelles helps diffuse the gas into the bulk.