title: Raman Spectroscopic Studies of Clathrate Hydrate Formation in the Presence of Hydrophobized Particles.
abstract: In the present work, Raman spectroscopy was used to study the structure of water molecules in the vicinity of glass particles with different hydrophobicity, immersed in water and in tetrahydrofuran and cyclopentane hydrates. The glass particle surfaces were clean (hydrophilic), coated with N,N-dimethyl-N-octadecyl-3-aminopropyl trimethoxysilyl chloride (partially hydrophobic), or coated with octadecyltrichlorosilane (hydrophobic). The Raman spectra indicate that, prior to nucleation, water molecules in the vicinity of hydrophobic surfaces are more ice-like ordered than those in the bulk liquid or near either hydrophilic or partially hydrophobic surfaces. Furthermore, the degree of hydrogen-bond ordering of water observed prior to hydrate nucleation, as measured by the ratio of the inter- and intramolecular Raman OH bands, was found to have an inverse relationship with the mean induction time for hydrate formation. Following hydration formation, no significant difference in the water molecule structure was observed in the hydrate phase based on their Raman OH bands, irrespective of surface hydrophobicity. These observations made with Raman spectroscopy provide the foundations for a quantitative link between hydrate nucleation promotion and water-ordering near solid surfaces, which could enable direct comparisons with results from corresponding molecular dynamics simulations.
authors.affiliation: School of Chemical Engineering, The University of Queensland , Brisbane, Australia.
authors.forename: Huijuan
authors.initials: H
authors.lastname: Li
authors.affiliation: School of Mechanical and Chemical Engineering, The University of Western Australia , Perth, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Stanwix
authors.affiliation: School of Mechanical and Chemical Engineering, The University of Western Australia , Perth, Australia.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Aman
authors.affiliation: School of Mechanical and Chemical Engineering, The University of Western Australia , Perth, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Johns
authors.affiliation: School of Mechanical and Chemical Engineering, The University of Western Australia , Perth, Australia.
authors.forename: Eric
authors.initials: E
authors.lastname: May
authors.affiliation: School of Chemical Engineering, The University of Queensland , Brisbane, Australia.
authors.forename: Liguang
authors.initials: L
authors.lastname: Wang