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Title: Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces

Abstract

Bubble attachment phenomena are examined using Molecular Dynamics Simulations (MDS) for the first time. The simulation involves a nitrogen nano bubble containing 906 nitrogen molecules in a water phase with 74,000 water molecules at molybdenite surfaces. During a simulation period of 1 ns, film rupture and displacement occurs. The attached nanobubble at the hydrophobic molybdenite face surface results in a contact angle of about 90º. This spontaneous attachment is due to a “water exclusion zone” at the molybdenite face surface and can be explained by a van der Waals (vdW) attractive force, as discussed in the literature. In contrast, the film is stable at the hydrophilic quartz (001) surface and the bubble does not attach. Contact angles determined from MD simulations are reported, and these results agree well with experimental and MDS sessile drop results. In this way, film stability and bubble attachment are described with respect to interfacial water structure for surfaces of different polarity. Interfacial water molecules at the hydrophobic molybdenite face surface have relatively weak interactions with the surface when compared to the hydrophilic quartz (001) surface, as revealed by the presence of a 3 Å “water exclusion zone” at the molybdenite/water interface. The molybdenite armchair-edge andmore » zigzag-edge surfaces show a comparably slow process for film rupture and displacement when compared to the molybdenite face surface, which is consistent with their relatively weak hydrophobic character.« less

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1417435
Report Number(s):
PNNL-SA-130354
Journal ID: ISSN 1643-1049; KC0301050
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Physicochemical Problems of Mineral Processing
Additional Journal Information:
Journal Volume: 54; Journal Issue: 1; Journal ID: ISSN 1643-1049
Country of Publication:
United States
Language:
English
Subject:
Molecular dynamics simulations (MDS); film stability; bubble attachment; interfacial water structure

Citation Formats

Jin, Jiaqi, Dang, Liem X., and Miller, Jan D. Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces. United States: N. p., 2018. Web. doi:10.5277/ppmp1821.
Jin, Jiaqi, Dang, Liem X., & Miller, Jan D. Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces. United States. doi:10.5277/ppmp1821.
Jin, Jiaqi, Dang, Liem X., and Miller, Jan D. Mon . "Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces". United States. doi:10.5277/ppmp1821.
@article{osti_1417435,
title = {Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces},
author = {Jin, Jiaqi and Dang, Liem X. and Miller, Jan D.},
abstractNote = {Bubble attachment phenomena are examined using Molecular Dynamics Simulations (MDS) for the first time. The simulation involves a nitrogen nano bubble containing 906 nitrogen molecules in a water phase with 74,000 water molecules at molybdenite surfaces. During a simulation period of 1 ns, film rupture and displacement occurs. The attached nanobubble at the hydrophobic molybdenite face surface results in a contact angle of about 90º. This spontaneous attachment is due to a “water exclusion zone” at the molybdenite face surface and can be explained by a van der Waals (vdW) attractive force, as discussed in the literature. In contrast, the film is stable at the hydrophilic quartz (001) surface and the bubble does not attach. Contact angles determined from MD simulations are reported, and these results agree well with experimental and MDS sessile drop results. In this way, film stability and bubble attachment are described with respect to interfacial water structure for surfaces of different polarity. Interfacial water molecules at the hydrophobic molybdenite face surface have relatively weak interactions with the surface when compared to the hydrophilic quartz (001) surface, as revealed by the presence of a 3 Å “water exclusion zone” at the molybdenite/water interface. The molybdenite armchair-edge and zigzag-edge surfaces show a comparably slow process for film rupture and displacement when compared to the molybdenite face surface, which is consistent with their relatively weak hydrophobic character.},
doi = {10.5277/ppmp1821},
journal = {Physicochemical Problems of Mineral Processing},
issn = {1643-1049},
number = 1,
volume = 54,
place = {United States},
year = {2018},
month = {1}
}