Historical perspective
On importance of external conditions and properties of the interacting phases in formation and stability of symmetrical and unsymmetrical liquid films☆

https://doi.org/10.1016/j.cis.2019.102085Get rights and content

Highlights

  • •

    in real dispersions, the liquid films formation is always highly dynamic.

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    rates of film syneresis and energy transfer determine bubble's collisions outcome.

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    when dissipated energy is re-supplied, a colliding bubble can bounce indefinitely.

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    if the liquid film survives initial disturbances it can reach equilibrium thickness.

  • •

    hydrophilic/hydrophobic properties affect mechanism of unsymmetrical film rupture.

Abstract

Importance of external conditions and properties of phases creating liquid films, in outcome of the air bubble collisions with liquid/air and liquid/solids interfaces in clean water and in liquid solutions, is critically reviewed. The review is focussed on initial stages of the liquid films formation by bubbles colliding with interfaces, as well as, on analysis of the most important factors responsible for the collision's outcome, that is, either the rapid bubble bouncing or formation of the symmetrical or unsymmetrical liquid films and their thinning to the critical rupture thicknesses. Data on formation of liquid films under dynamic conditions, both in pure liquids and solutions of electrolytes and various surface-active substances, are reviewed and importance of hydrodynamic boundary conditions at interacting interfaces for energy balance in the system is discussed. It is shown that the liquid films stability, which in stagnant systems are directly determined by properties of the liquid/gas and liquid/solid interfaces, can be quite different in dynamic environment. A mechanism of the bubble bouncing from various interfaces in terms of interplay between energy exchange and kinetics of liquid film drainage is analyzed. It is shown that this mechanism is universal and irrelevant on the nature of interacting phases. Moreover, mechanisms responsible for wetting (unsymmetrical) film stability under dynamic conditions are discussed in light of the most recent studies, showing a crucial role of electrolyte, kind and concentration of surface-active substances, electrical surface charge, hydrophilic/hydrophobic properties of solids and presence of air entrapped (nano- and/or micro-bubbles) at surfaces of highly hydrophobic solids in the liquid films rupture.

Section snippets

Symbols and abbreviations

σsurface tension
ρdensity
μviscosity
Tkinetic energy of an air bubble/liquid system
Vtotal potential energy of an air bubble/liquid system
Vggravitational component of the total potential energy
Vssurface component of the total potential energy
Drate of viscous dissipation of energy
Aair bubble area
ggravitational acceleration
Ωtotal volume of a computational domain (liquid column)
x, rcoordinates of a liquid column in cylindrical coordinates system
uliquid velocity vector, with components u

Liquid films in clean liquids under dynamic conditions

As it has been already discussed above, for formation of stable DS, containing millions of single liquid films, surface-active substances (SAS) are needed as stabilizing agents. Adsorption of the SAS molecules at various interfaces changes kinetics of drainage of the liquid films, hence the stability and timescale of their rupture [19,[22], [23], [24], [25], [26], [27], [28], [29]]. This is mainly due to changes in hydrodynamic interfaces boundary conditions [24,[30], [31], [32], [33], [34]].

Liquid films in solutions under dynamic conditions

If external disturbances related to the collisions between interacting phases do not cause rupture of the liquid films then they reach their equilibrium thicknesses where the specific forces of interactions in thin liquid layers (DLVO theory – disjoining pressure) come to act. The total disjoining pressure in the thin film is considered as an additive sum of different components, namely electrostatic forces, van der Waals forces and non-DLVO components, like for example solvation, hydrophobic,

Concluding remarks

Importance of dynamic effects, always accompanying the initial stages of liquid films formation by the bubbles colliding with different interfaces, both in pure liquids and solutions of electrolytes and various surface-active substances, is described. Influence of external disturbances, hydrodynamic boundary conditions at the interfaces of interacting phases, effect of electrical surface charge, presence of electrolyte and various types of surface-active substances on formation and stability of

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

Partial financial support from the Polish National Science Centre (grant No. 2017/25/B/ST8/01247) and the project by the statutory research found of ICSC PAS is acknowledged with gratitude.

References (116)

  • B.V. Derjaguin et al.

    Rabinovich Y

    Adv Colloid Interface Sci

    (1987)
  • N.V. Churaev et al.

    Adv Colloid Interface Sci

    (1992)
  • D. Exerowa et al.

    Adv Colloid Interface Sci

    (1992)
  • R. Sedev et al.

    Adv Colloid Interface Sci

    (1999)
  • D.S. Valkovska et al.

    Adv Colloid Interface Sci

    (2002)
  • D. Exerowa et al.

    Adv Colloid Interface Sci

    (2003)
  • E.D. Manev et al.

    Adv Colloid Interface Sci

    (2005)
  • M. Krasowska et al.

    Adv Colloid Interface Sci

    (2007)
  • D. Exerowa et al.

    Adv Colloid Interface Sci

    (2009)
  • E. Mileva et al.

    Curr Opin Colloid Interface Sci

    (2008)
  • E. Mileva

    Curr Opin Colloid Interface Sci

    (2010)
  • E. Bonaccurso et al.

    Curr Opin Colloid Interface Sci

    (2008)
  • S.I. Karakashev et al.

    Adv Colloid Interface Sci

    (2014)
  • S.I. Karakashev et al.

    Adv Colloid Interface Sci

    (2015)
  • G. Gochev

    Curr Opin Colloid Interface Sci

    (2015)
  • G. Gochev et al.

    Adv Colloid Interface Sci

    (2016)
  • B.W. Ninham et al.

    Curr Opin Colloid Interface Sci

    (2017)
  • K. Malysa

    Adv Colloid Interface Sci

    (1992)
  • D. Langevin

    Comptes Rendus Mécanique

    (2017)
  • J. Zawala et al.

    Colloids Surf A Physicochem Eng Asp

    (2016)
  • J. Zawala et al.

    Colloids Surf A Physicochem Eng Asp

    (2017)
  • M. Kostoglou et al.

    Colloids Surf A Physicochem Eng Asp

    (2011)
  • R.G. Horn et al.

    Adv Colloid Interface Sci

    (2011)
  • D. Langevin

    Curr Opin Colloid Interface Sci

    (2015)
  • M. Wegener et al.

    Int J Heat Mass Trans

    (2014)
  • R. Manica et al.

    Adv Colloid Interface Sci

    (2016)
  • M. Krzan et al.

    Colloids Surf A Physicochem Eng Asp

    (2007)
  • V. Ulaganathan et al.

    Colloids Surf A Physicochem Eng Aspects

    (2014)
  • J. Zawala et al.

    Adv Colloid Interface Sci

    (2015)
  • S.S. Dukhin et al.

    Adv Colloid Interface Sci

    (2015)
  • S.S. Dukhin et al.

    Colloids Surf A Physicochem Eng Asp

    (2016)
  • V. Ulaganathan et al.

    Colloids Surf A Physicochem Eng Asp

    (2016)
  • J. Zawala et al.

    Colloids Surf A Physicochem Eng Asp

    (2017)
  • T. Sanada et al.

    Chem Eng Sci

    (2005)
  • F. Suñol et al.

    Colloids Surf A Physicochem Eng Asp

    (2010)
  • P. Attard

    Adv Colloid Interface Sci

    (2003)
  • M.A. Hampton et al.

    J Colloid Interface Sci

    (2008)
  • M.A. Hampton et al.

    Adv Colloid Interface Sci

    (2010)
  • M. Krasowska et al.

    Curr Opin Colloid Interface Sci

    (2019)
  • C. Yang et al.

    J Colloid Interface Sci

    (2001)
  • J. Zawala et al.

    Int J Miner Process

    (2008)
  • J.D. Miller et al.

    Colloids Surf A Physicochem Eng Aspects

    (2004)
  • D. Kosior et al.

    Colloids Surf A Physicochem Eng Asp

    (2014)
  • I.B. Ivanov et al.

    Chem Eng Sci

    (1985)
  • A. Scheludko

    Adv Colloid Interface Sci

    (1967)
  • D. Exerowa et al.

    Foam and foam films: theory, experiment, application

    (1997)
  • R. Manica et al.

    Soft Matter

    (2016)
  • B. Liu et al.

    Phys Rev Lett

    (2019)
  • I.U. Vakarelski et al.

    Langmuir

    (2018)
  • M. Krasowska et al.

    J Phys Chem C

    (2019)

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    ☆

    This review is to honor Dotchi Exerowa and Dimo Platikanov for their extraordinary contribution to the colloid and interface science, especially in the area of foam films, foams, wetting films and development of unique methodologies to study forces of interactions in thin liquid layers.

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