4.3 Comparison of the Ionic Model with Other Microscopic Models of Water
147
permeability of the nanotube-based membranes was several orders of magnitude
higher than those for continuum hydrodynamic models. Thus, the increased permeability is not a result of the absence of hydrogen bonds, but the result of the reduction
of interaction on the intermolecular level, as is found between ionic species in the
ionic model. The result of Holt et al. correlated with the experimental measurement
of the electrical conductivity of nano-confined water by Artemov et al. [42], which
was found to be five orders of magnitude higher than that for bulk water, and was
explained by means of the ionic model of water. These results confirm that among
short-order molecular–molecular interaction, there is a long-order intermolecular
interaction in water, which can be changed by the confinement.
4. Water viscosity changes in a strong electric field (more evidence for long-range
order in water)
Water is known to have anomalous properties being placed in a strong external
electric field (several kV/cm or more) [37]. In particular, the phenomenon, known as
a floating water bridge has been observed in the gap between two beakers under high
voltage filled with chemically pure water [43]. Fuchs studied [44] this phenomenon
and found that the bridge exhibits the “hidden” properties of water that only become
visible in a strong electric field. In the Bernal–Fowler model, there are no such
configurations of molecular dipoles, which are stable enough to form a free-hanging
water wire no matter how large the external electric field is. On the contrary, the ionic
model provides an intermolecularly polarizable environment, which exhibits longorder caused by the ionic “sub-lattice” (see Fig. 4.5). The relative displacement of
the positive and negative intrinsic ions of water by an external electric field provides
the electrostatic stress necessary to counteract gravity. For the analysis of the effect
of the floating water bridge in the ionic model of water see Sect. 5.5.
5. The absence of hydrogen bonds between H 3 O
+ ion and H 2 O molecules (evidence
for the long-range interaction of ions with water molecules)
Botti et al. studied [45] the microscopic structure of a concentrated HCl solution by
neutron diffraction and found that the binding of water by the H 3 O
+ ion occurs at a
greater distance than that in the case of molecule–molecule interaction. Analyzing
the scattering data, the authors found that the local density around ions is higher
than that for neutral molecules as the intense peak at 1.45 Å appears on its radial
distribution function. This shrinkage of water induced by ions is in line with the ionic
model of water, which operates with swarms of water molecules around ionic species
(see Fig. 4.5). The increase of the local density around ions should be compensated
for by a decrease between the ions.
6. Semi-classical molecular-dynamic simulations (evidence that water is not an
ensemble of long-lived H 2 O molecules)
As discussed in Chap. 1, the density-functional theory (DFT)-based molecular
dynamics are inapplicable for the modeling of the electrodynamics of water, as,
minimizing the computational costs, it significantly underestimates the effect of
proton exchange on water structure. The excess-proton trajectories for ion recombination predicted by DFT do not agree with the diffusive trajectories observed in
147
permeability of the nanotube-based membranes was several orders of magnitude
higher than those for continuum hydrodynamic models. Thus, the increased permeability is not a result of the absence of hydrogen bonds, but the result of the reduction
of interaction on the intermolecular level, as is found between ionic species in the
ionic model. The result of Holt et al. correlated with the experimental measurement
of the electrical conductivity of nano-confined water by Artemov et al. [42], which
was found to be five orders of magnitude higher than that for bulk water, and was
explained by means of the ionic model of water. These results confirm that among
short-order molecular–molecular interaction, there is a long-order intermolecular
interaction in water, which can be changed by the confinement.
4. Water viscosity changes in a strong electric field (more evidence for long-range
order in water)
Water is known to have anomalous properties being placed in a strong external
electric field (several kV/cm or more) [37]. In particular, the phenomenon, known as
a floating water bridge has been observed in the gap between two beakers under high
voltage filled with chemically pure water [43]. Fuchs studied [44] this phenomenon
and found that the bridge exhibits the “hidden” properties of water that only become
visible in a strong electric field. In the Bernal–Fowler model, there are no such
configurations of molecular dipoles, which are stable enough to form a free-hanging
water wire no matter how large the external electric field is. On the contrary, the ionic
model provides an intermolecularly polarizable environment, which exhibits longorder caused by the ionic “sub-lattice” (see Fig. 4.5). The relative displacement of
the positive and negative intrinsic ions of water by an external electric field provides
the electrostatic stress necessary to counteract gravity. For the analysis of the effect
of the floating water bridge in the ionic model of water see Sect. 5.5.
5. The absence of hydrogen bonds between H 3 O
+ ion and H 2 O molecules (evidence
for the long-range interaction of ions with water molecules)
Botti et al. studied [45] the microscopic structure of a concentrated HCl solution by
neutron diffraction and found that the binding of water by the H 3 O
+ ion occurs at a
greater distance than that in the case of molecule–molecule interaction. Analyzing
the scattering data, the authors found that the local density around ions is higher
than that for neutral molecules as the intense peak at 1.45 Å appears on its radial
distribution function. This shrinkage of water induced by ions is in line with the ionic
model of water, which operates with swarms of water molecules around ionic species
(see Fig. 4.5). The increase of the local density around ions should be compensated
for by a decrease between the ions.
6. Semi-classical molecular-dynamic simulations (evidence that water is not an
ensemble of long-lived H 2 O molecules)
As discussed in Chap. 1, the density-functional theory (DFT)-based molecular
dynamics are inapplicable for the modeling of the electrodynamics of water, as,
minimizing the computational costs, it significantly underestimates the effect of
proton exchange on water structure. The excess-proton trajectories for ion recombination predicted by DFT do not agree with the diffusive trajectories observed in