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Physica A 314 (2002) 696705 www.elsevier.com/locate/physa
 

Summary: Physica A 314 (2002) 696­705
www.elsevier.com/locate/physa
Nanobubbles: the big picture
Phil Attard, Michael P. Moody, James W.G. Tyrrell
Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
Abstract
Nanobubbles, whose existence on hydrophobic surfaces immersed in water has previously been
inferred from measurements of long-ranged attractions between such surfaces, are directly imaged
by tapping mode atomic force microscopy. It is found that the nanobubbles cover the surfaces
in an irregular, interconnected or close-packed network whose morphology is dependent on pH
and whose lifetimes are at least of the order of hours. Their height is of the order of 30 nm and
their radius of curvature is of the order of 100­300 nm. It appears that the nanobubbles form
from a solution supersaturated with air. A thermodynamic and statistical mechanical analysis of
the homogeneous nucleation of liquid droplets from a supersaturated vapour shows that although
a single droplet can be in equilibrium with a ˙nite volume of gas, for a gas reservoir the
equilibrium state is represented by a single macroscopic droplet, which grows by collisions and
by Ostwald ripening. It is concluded that the electric double-layer repulsion between neighbouring
nanobubbles on the hydrophobic surface plays a role in their stabilisation.
c 2002 Elsevier Science B.V. All rights reserved.
PACS: 61.16.Ch; 68.10.Cr; 82.65.Dp

  

Source: Attard, Phil - School of Chemistry, University of Sydney

 

Collections: Chemistry