Exclusion Zone Phenomena in Water—A Critical Review of Experimental Findings and Theories
1
Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD 20892, USA
2
School of Biomedical Sciences, Faculty of Health, Institute of Health and Biomedical Innovation, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia
3
School of Earth, Environmental and Biological Sciences, Science and Engineering Faculty, Institute for Future Environments, QUT, Brisbane, QLD 4000, Australia
4
School of Biomedical Sciences, Faculty of Health, Institute of Health and Biomedical Innovation, QUT, Australian Prostate Cancer Research Centre—Queensland, Translational Research Institute, Brisbane, QLD 4059, Australia
*
Authors to whom correspondence should be addressed.
Int. J. Mol. Sci. 2020, 21(14), 5041; https://doi.org/10.3390/ijms21145041
Received: 9 May 2020 / Revised: 27 June 2020 / Accepted: 13 July 2020 / Published: 17 July 2020
(This article belongs to the Special Issue The Structure and Function of the Second Phase of Liquid Water)
The existence of the exclusion zone (EZ), a layer of water in which plastic microspheres are repelled from hydrophilic surfaces, has now been independently demonstrated by several groups. A better understanding of the mechanisms which generate EZs would help with understanding the possible importance of EZs in biology and in engineering applications such as filtration and microfluidics. Here we review the experimental evidence for EZ phenomena in water and the major theories that have been proposed. We review experimental results from birefringence, neutron radiography, nuclear magnetic resonance, and other studies. Pollack theorizes that water in the EZ exists has a different structure than bulk water, and that this accounts for the EZ. We present several alternative explanations for EZs and argue that Schurr’s theory based on diffusiophoresis presents a compelling alternative explanation for the core EZ phenomenon. Among other things, Schurr’s theory makes predictions about the growth of the EZ with time which have been confirmed by Florea et al. and others. We also touch on several possible confounding factors that make experimentation on EZs difficult, such as charged surface groups, dissolved solutes, and adsorbed nanobubbles.
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Keywords:
water; exclusion zone; diffusiophoresis; repulsive van der Waals
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MDPI and ACS Style
Elton, D.C.; Spencer, P.D.; Riches, J.D.; Williams, E.D. Exclusion Zone Phenomena in Water—A Critical Review of Experimental Findings and Theories. Int. J. Mol. Sci. 2020, 21, 5041. https://doi.org/10.3390/ijms21145041
AMA Style
Elton DC, Spencer PD, Riches JD, Williams ED. Exclusion Zone Phenomena in Water—A Critical Review of Experimental Findings and Theories. International Journal of Molecular Sciences. 2020; 21(14):5041. https://doi.org/10.3390/ijms21145041
Chicago/Turabian StyleElton, Daniel C., Peter D. Spencer, James D. Riches, and Elizabeth D. Williams 2020. "Exclusion Zone Phenomena in Water—A Critical Review of Experimental Findings and Theories" International Journal of Molecular Sciences 21, no. 14: 5041. https://doi.org/10.3390/ijms21145041
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