Title: Silica Surface States and their Wetting Characteristics

Abstract

The wetting characteristics of silica (SiO₂) surfaces can be described by molecular dynamics (MD) and ab initio simulations, including comparison of silica surfaces (talc (001), siloxanated quartz, tridymite (001) and quartz (001)), some of which have not been considered previously in the literature. Classic MD and ab initio simulation methods have been used to determine the contact angle, interfacial water structure, hydroxylation reaction and hydration energy, the results of which are compared with experimental results reported in the literature. Additionally, wetting of silica surfaces depends on surface polarity and extent of hydroxylation. The non-polar siloxane surfaces are characterized by a contact angle of about 80°, an MD ‘water exclusion zone’ of about 3 Å, a relaxed interfacial water orientation, inertness to hydroxylation and minimal hydration energy. The polar silica surfaces can be wetted by water and have a more ordered interfacial water structure. Silanol groups form at the polar silica surface during hydroxylation reactions, and the calculated hydration energy of -1·2 and -1·6 eV matches the experimental heat of immersion measurements reported in the literature, which correspond to hydrogen (H) bonding with interfacial water. In conclusion, fundamental understanding of silica surfaces is important for understanding flotation phenomena and fluid flowmore » in silica nanopores.« less

Authors:

Jin, Jiaqi ^[1]; Wang, Xuming ^[1]; Wick, Collin D. ^[2]; Dang, Liem X. ^[3]; Miller, Jan D. ^[1]

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+ Show Author Affiliations

1. Univ. of Utah, Salt Lake City, UT (United States)
2. Louisiana Tech Univ., Ruston, LA (United States)
3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Publication Date:

Wed Nov 13 00:00:00 EST 2019

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Multi-Scale Fluid-Solid Interactions in Architected and Natural Materials (MUSE); Univ. of Utah, Salt Lake City, UT (United States). Multi-Scale Fluid-Solid Interactions in Architected and Natural Materials (MUSE)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1595107

Grant/Contract Number:  

SC0019285

Resource Type:

Accepted Manuscript

Journal Name:

Surface Innovations

Additional Journal Information:

Journal Volume: 8; Journal Issue: 3; Journal ID: ISSN 2050-6252

Publisher:

ICE Publishing

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; Silica; Polarity; Wetting; Contact Angle; Molecular Dynamics Simulation; Interfacial Water Structure; Ab-initio Simulation; Hydroxylation; Hydration Energy