Adsorption‐Inhibition of Clathrate Hydrates by Self‐Assembled Nanostructures

Abstract

The mechanism by which safranine O (SFO), an ice growth inhibitor, halts the growth of single crystal tetrahydrofuran (THF) clathrate hydrates was explored using microfluidics coupled with cold stages and fluorescence microscopy. THF hydrates grown in SFO solutions exhibited morphology changes and were shaped as truncated octahedrons or hexagons. Fluorescence microscopy and microfluidics demonstrated that SFO binds to the surface of THF hydrates on specific crystal planes. Cryo-TEM experiments of aqueous solutions containing millimolar concentrations of SFO exhibited the formation of bilayered lamellae with an average thickness of 4.2 � 0.2 nm covering several μm 2 . Altogether, these results indicate that SFO forms supramolecular lamellae in solution, which might bind to the surface of the hydrate and inhibit further growth. As an ice and hydrate inhibitor, SFO may bind to the surface of these crystals via ordered water molecules near its amine and methyl groups, similar to some antifreeze proteins.

A Microfluidic Approach for the Study of Ice and Clathrate Hydrate Crystallization

“…After the hydrate crystals were allowed to adsorb the inhibitor molecules from the solution, an inhibitor-free solution was injected into the channels. Figure 5 presents THF hydrates after solution exchange with two types of inhibitors: AFGP 1-5 labeled with fluorescein isothiocyanate (FITC) (Figure 5A) and safranine O (see Table of Materials), which is a fluorescence dye 26 (Figure 5B). This is the first demonstartion of an AFGP binding to the surface of a clathrate hydrate.…”

A Microfluidic Approach for the Study of Ice and Clathrate Hydrate Crystallization

“…1. To obtain THF hydrates, prepare a THF/water solution with a molar ratio of 1:15, which is a volume ratio of 1:3.3 26 . Maintain this ratio in all solutions used in the following experiments, including those containing AF(G)Ps or other inhibitors.…”