(186j) Adsorption of Kinetic Inhibitors On Clathrate Hydrates

This work presents the adsorption behaviors of two kinetic inhibitors, polyvinyl pyrrolidone (PVP) and polyvinylcaprolactam (PVCap), on cyclopentane (CP) hydrates. CP hydrate particles are negative in the absence of inhibitors, and they become neutral as the inhibitor concentration increases. The adsorption of PVP is well fitted to the Langmuir-type, and the isotherm of PVCap is of the BET-type. Although PVCap monomers preferably adsorb on hydrates compared with PVP monomers, the isotherms of PVP and PVCap overlap with each other at concentrations up to 0.05 mM, corresponding to a water-based weight fraction of 0.6% and 0.5 % for PVP and PVCap, respectively. Above this concentration, a multilayer adsorption occurs for PVCap, giving rise to a thick adsorption layer, and thus making PVCap more effective in retarding the diffusion of hydrate formers from the bulk phase to the hydrate surface where the hydrate growth prefers to proceed. The determination of inhibitor adsorption isotherms can be utilized to screen a new effective kinetic hydrate inhibitors.