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Abstract: Although electrochemical stability is an essential factor in relation to the potential applications of ionic clathrate hydrates to solid electrolytes, most studies regarding the proton conductors have focused on their ionic conductivity and thermal stability. Solid electrolytes in various electrochemical devices have to endure the applied potentials; thus, we examined the linear sweep voltammograms of various tetraalkylammonium hydroxide hydrates in order to shed light on the trend of electrochemical stability depending on the hydrate structure. We revealed that the electrochemical stability of Me4NOH hydrates is mainly affected by both their ionic concentration and cage occupancy. In particular, the true clathrate structures of β-Me4NOH hydrates are more electrochemically stable than their α-forms that possess partially broken hydrogen bonds. We also observed that the binary THF–Pr4NOH and pure Bu4NOH clathrate hydrates exhibit greater electrochemical stability than those of pure Me4NOH hydrates having lower or similar ionic concentrations. These results are considered to arise from the fact that each of the Pr4N+ and Bu4N+ ions occupies an extended space comprising four cages, which leads to stabilization of the larger unit, whereas a Me4N+ ion is completely included only in one cage. [Copyright &y& Elsevier]

In the present study, the hydrate anti-agglomerant (AA) performance of three biodegradable emulsifiers (Span 80, lecithin, and lanolin) was evaluated in oil-dominated systems using high-pressure rheological tests. The viscosity variations of the fluid systems were examined depending on the concentration of the emulsifiers and water cut during the entire hydrate formation process. The biodegradable emulsifying AAs prevented the drastic increase in the viscosity of the CH 4 hydrate slurry in mineral oil and significant hydrate agglomeration. The AA performance decreased in the following order: Span 80, lecithin, and lanolin. These biodegradable AAs create W/O (water-in-oil) emulsions, namely, small water droplets in mineral oil, by which more water is converted to hydrate that is well dispersed in the oil phase than in the cases without the AAs. The hydrate aggregates formed in the absence of the AAs contain more unconverted water that acts as a capillary bridge for hydrate aggregation or that is confined at the core of the hydrate particles by the partial conversion of water. The density of the dispersed hydrate particles in the AA tests is lower than that of the hydrate aggregates formed in the absence of the AAs. This is due to the unconverted water confined in the aggregates. Therefore, the AAs not only prevent hydrate agglomeration but also reduce the hydrate bedding risk by increasing the conversion of water to hydrate. Image 1 • Performance of a biodegradable emulsifier was evaluated for gas hydrate inhibition. • Viscosity and pressure variations of oil-dominated fluid systems were examined. • Emulsifier makes hydrates dispersed well in oil phase. • Hydrate agglomeration was prevented and reduce hydrate bedding risk reduced. [ABSTRACT FROM AUTHOR]

• Expression of AFPs on E. coli using cell surface display strategy was investigated. • Kinetic inhibition performance of AFPs was tested. • Monomer to hexamers of AFPs were displayed on surface of bacterial cells. • AFPs exhibited higher KHI effectiveness with increasing number of attached peptides. • KHI performance of AFPs is achieved with higher dosages of the cultures. The expression of anti-freeze proteins (AFPs) on the Escherichia coli using the cell surface display (CSD) strategy was investigated to determine the feasibility of the method as a potential application of kinetic hydrate inhibitors. Monomers to hexamers of type II and III AFPs were displayed on the surfaces of bacterial cells. The kinetic inhibition performance of the AFPs on the synthetic natural gas hydrate formation was tested. The displayed AFPs exhibited higher KHI effectiveness with the increase in the number of peptides attached to the cells. In addition, best KHI performance of the AFPs could be achieved with higher dosages of the cultures when the concentration of the inducer is optimized, regardless of AFP type. Only a small portion of AFPs in the cell cultures exhibited considerable KHI performance, which implies that the CSD could be an effective strategy, reducing the cost for the production and purification of the AFPs. [ABSTRACT FROM AUTHOR]