20067
2006, 110, 20067-20072 Published on Web 09/23/2006
Transient Oxygen Clathrate-like Hydrate and Water Networks Induced by Magnetic Fields Sumio Ozeki* and Ichiro Otsuka Department of Chemistry, Faculty of Science, Shinshu UniVersity, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan ReceiVed: July 7, 2006; In Final Form: August 31, 2006
Recently, careful experiments of oxygen-dissolved pure water treated by high magnetic fields showed indirectly the existence of magnetic field-affecting water (MFA water), which brought about a decrease in the contact angle of water on metals, an increase in the electrolytic potential of water, inhibition of metal corrosion, and changes in the crystal structure of calcium carbonate due to magnetic treatment. Here we report the infrared and Raman spectroscopic evidence indicating quasi-stable structures in the MFA water; oxygen clathratelike hydrate and developed water networks, which were induced by magnetic interactions while a vacuumdistilled water, followed by oxygen exposure, crossed a steady magnetic field. The mechanism of MFA water formation and survival under thermal fluctuation is a challenging problem for the science community.
Many people using “magnetized water” believe in its ability to inhibit corrosion and scale formation in pipes and boilers, promote growth of plants and fishes, dye strings and cloths, and so forth;1 thus, many kinds of devices for magnetic field treatment (MT) of tap and industrial water are sold commercially worldwide. However, most people in scientific fields still suspect the existence of such magnetized water because there is no reason for pure water to be changed by MT and so many uncontrollable factors such as magnetic impurities, although there are many reports on the MT of water;1-13 the structure change of CaCO3,5,8,11 changes of crystal growth2,4,6 and properties,3,7,9 and inhibition of corrosion,13 and changes in water properties.10,12 Higashitani et al.8-10 stressed that the hydration layer around ions and colloids in aqueous solutions should be thickened by MT. Ozeki et al.14-16 inferred from the promotion in water adsorption and the lower pressure shift of the capillary condensation onset that the water/solid interaction in vacuum should be enhanced even by steady magnetic fields. A few papers recently reported that some properties of pure water changed very slightly when the pure water stood in steady, homogeneous magnetic fields: a 0.1% increase in the refractive index of a pure water at 10 T,17 a 5 mK rise in the melting point of ice at 5 T,18and a 0.3% increase in the intensity of the near-infrared band of 1930 nm at 14 T.19 These magnetic field effects were attributed to hydrogen-bond development. The changes due to steady, homogeneous magnetic fields were unreasonably larger than theoretical expectation, but very much smaller compared with the MT effects, suggesting that the magnetic flux changes should affect strongly the structure or properties of oxygenated water. In a previous paper,12 the change of the interfacial energy of the water/Pt interface due to MT was estimated to be -15 mJ cm-2, suggesting that a hydrated layer on a Pt surface may develop in MFA water. The increase in the energy corresponds * To whom correspondence should be addressed. E-mail: sozeki@ shinshu-u.ac.jp.
10.1021/jp0642793 CCC: $33.50
to ca. 200 nm in thickness of bulk ice. Because such a layer thickness seems to be too thick, the hydration energy near the solid surface should be enhanced. The interaction modification might arise from clathrate-like hydrates, although the O2 clathrate in bulk water is formed only over 109.2 atm at -1.0 °C.14 Our careful experiments, however, very recently showed the existence of “magnetic field-affecting water” (MFA water) indirectly through the remarkable results on contact angle, electrolysis, Raman bands, metal corrosion, and calcium carbonate formation.11-13 The MFA water required O2 and the relative motion of water against a magnetic flux and seemed to be accompanied by the formation of clathrate-like hydrate of O2 and promotion of hydration layer.12 In this report, we have tried to obtain the spectroscopic evidence indicating the existence of a quasi-stable structure in the MFA water, an oxygen clathrate-like hydrate, and developed water networks. Any experiment for MFA water has been carried out at 298 K after checking the contact angle, θ, of water on a Pt plate, whose changes are given as MT(∆θ). MFA water was prepared by MT under various atmospheres (vacuum, O2, and air) of a water distilled from ultrapure water in vacuum. In some cases, all procedures, that is, distillation, MT, and contact angle and spectroscopic measurements, were carried out under vacuum. Two sets of greaseless Pyrex distillation flasks with vacuum valves were made, which were separable in order to connect to the vacuum chamber for contact angle and IR measurements. The flasks were connected to a vacuum line (1 mPa) with a greaseless glass joints. Afterwards, pure water (Milli-Q water; 18 MΩ) in a reservoir furnished in the vacuum line was degassed by repeating a freezing-pumping-melting cycle more than five times and was followed by distillation due to temperature difference under vacuum. After distillation, in some cases O2 (purity: 99.99%) of various pressures or air (1 atm) was introduced through the vacuum line and stood until dissolution equilibrium. One of the flasks containing the distilled water was treated by reciprocating motion at 30 cycles/min (av © 2006 American Chemical Society
20068 J. Phys. Chem. B, Vol. 110, No. 41, 2006 0.32 m/s) for 2.5 h in the region of more than 2 T across the center (e6 T) of a steady magnetic field of a JASTEC TMTD6T150E1 superconducting magnet at 298 K. Another flask was also treated at zero field by the same procedures at the same time (NMT). The gas exposure and MT were carried out very carefully to avoid bubble formation. The two flasks containing the distilled water were connected to the chambers for contact angle and IR measurements under the same atmosphere as the distillation cell with greaseless flanges, and water droplets were gently dropped down from each flask on a Pt plate and into the thin interstice (without a spacer) between a pair of CaF2 windows, respectively, in vacuum, O2, or air. The contact angle of both MT and NMT waters was measured at the same time for both sides of several drops with a CCD camera system, as described previously.11,12 Water for Raman spectra was distilled into a vacuum fluorescent cell with a greaseless vacuum valve, exposed to O2 or air, and then followed by MT at 298 K and av 0.09 m/s. FT-IR spectra of MFA water were measured at 298 K using a JEOL FTIR Diamond-20 (600-4000 cm-1) with a vacuum Pyrex glass cell with a vacuum valve and a set of CaF2 windows whose light path was varied without any spacer and a JASCO FT/IR-6100 (1000-7000 cm-1) with a 0.1 mm light-path IR liquid cell in air. Microscopic Raman spectra of water film (2 mm) on a Pyrex glass plate were measured with a JASCO Laser Raman NRS-3200 spectrometer (100- 4000 cm-1) in air. Raman spectra of water also were measured at 298 K using a Shimadzu RF450 spectrofluorometer with a 10 mm fluorescence cell with a vacuum valve. The resolution was at most (1 nm (25 cm-1). Figure 1 shows atmosphere and magnetic field dependences of MT effects on IR absorption of vacuum-distilled water and the water exposed to O2 and air. The IR spectrum of the vacuumdistilled water remained unchanged by MT at 6 T (6T-MT). When the vacuum-distilled water was exposed to O2 of 98 Torr (∆θ ) 0°), no spectrum change was observed, as seen in Figure 1I (lower). 6T-MT of the vacuum-distilled water exposed to 98 and 695 Torr O2 decreased their contact angle, which are referred to as 6T-MT(∆θ ) -3.6°; 98 Torr O2) and 6T-MT(∆θ ) -6.8°; 695 Torr O2), and also induced new IR bands: the doublet peak at 1087 and 1046 cm-1 and the band in the range of 2840-2985 cm-1 whose intensities increased with O2 pressure. Air (1 atm) exposure of the distilled water never changed the IR spectrum again, but 6T-MT(∆θ ) -7.4°; air) also induced the new bands, whose difference spectrum between MT and NMT spectra (upper part of I) showed the doublet peak at 1085 and 1044 cm-1 and the band comprising 2981 (main peak), 2938, 2910, 2881, and 2839 cm-1, compared to the difference spectrum for the vacuum-distilled water that has no new bands. Increasing magnetic field intensity for MT (Figure 1II), all IR bands of usual water at 6900 cm-1 (overtone), 5180 cm-1 (combination), 3445 and 3210 cm-1 (stretching mode), 2100 cm-1 (association band), 1650 cm-1 (bending mode), and 900 cm-1 (restricted rotational mode), including the new bands (Figure 1III), were markedly strengthened by 3T-MT(∆θ ) -3.3°) and 6T-MT(∆θ ) -6.5°). Figure 1IV shows that the difference absorption intensities of the doublet peak increased with increase in O2 concentration in water, magnetic field intensity of MT, and contact angle decrease |∆θ|, demonstrating that the contact angle decrease or hydration enhancement due to MT should arise from some IR active structure induced by MT of O2-dissolving water. These new peaks and intensity enhancement in all bands disappeared by 5 min ultrasonication (∆θ ) 0°) of any MFA water. Moreover, when the vacuum-
Letters distilled water exposed to air was silently stood under a 6 T magnetic field for 13h, the MT water (∆θ ) -1.8°) showed no difference with NMT water in the IR spectra, suggesting that no fine gas bubble in water should be responsible for MFA water and that changes of magnetic flux, but not magnetic flux itself, should bring about MFA water, respectively. Because the promotion of IR bands due to MT suggests the increase in number of OH and OH connection, MFA water would contain developed hydrogen-bonded networks. Mass spectroscopy, however, gave no meaningful differences between NMT and MFA water, that is, no cluster size or hydrogen-bond development due to MT, although THz absorption spectroscopy (e 20 cm-1) suggested promotion in dielectric properties of collective motion of an MFA water. The Raman spectrum of the vacuum-distilled water film, measured with a Laser Raman spectrometer in air, was unchanged by MT(∆θ ) 0°), but the appearance of new faint bands at around 1080 and 1045 cm-1 (doublet) and 2981 cm-1 (Figure 2I), as well as increase in the bands of usual water at around 1600 cm-1 and in the region of 3200-3450 cm-1, were observed when followed by 6T-MT(∆θ ) -6.5°) after air exposure. These suggest that the MFA water should contain a structure having IR- and Raman-active vibration modes, such as O2 clathrate-like hydrates. Raman spectra of water were also measured at 298 K using a spectrofluorometer with a 10 mm fluorescence cell with a vacuum valve. The resolution was at most (1 nm. After water was distilled from a container having pure water into the fluolescent cell in vacuum, the vacuum-distilled water was exposed to 690 Torr O2 and then the sealed cell was treated by 6T-MT(∆θ ) -4.8°) at 298 K and 0.09 m/s. The Raman spectrum of the vacuum-distilled water was again quite unchanged by MT(∆θ ) 0°). Though the Raman spectrum was also unchanged by oxygenation of the distilled water, after followed by the MT(∆θ ) -4.8°) the Raman bands at around 1650, 3250, and 8400 cm-1 were enhanced significantly and a new band in the region of 5000 cm-1 appeared (not shown). The band intensities decreased down to the initial intensity within 24 h. Figure 2II shows the MT effects on Raman spectra of air-exposed water, measured by excitation due to lights of λex ) 350, 400, and 500 nm. 3T-MT(∆θ ) -3.8°) and 6TMT(∆θ ) -7.6°) enhanced markedly all of the Raman bands of water and presumably induced the appearance of several new bands in the regions of 4200, 4900, and 5600 cm-1, corresponding to the overtones and combination bands of the bending and stretching modes of hydrogen-bonded water. The new bands suggest again that the forbidden transition in the Raman combination modes should become forgiven by symmetry changes of O2 clathrate-like hydrates with the MT. Any change in the spectra with MT disappeared at 3 days after MT or after temperature rise to 323 K for 10 min, at which the contact angle recovered the initial value (∆θ ) 0°). We do not think that the remarkable peaks induced by MT arise from any contamination or any new chemical product because NMT spectra had no such peaks and short ultrasonication or temperature rise of MFA water made the peaks disappear. Notwithstanding, the wavenumbers of the new peaks forced us to reserve the conclusion because unfortunately the peaks appeared near the peaks of C-H stretching modes (30002940 cm-1) of organics as most probable contamination and at around similar position to silica bands (around 1100 cm-1), which reminds us of the “polywater” problem, at which D2O brought about no change of the faint 1100 cm-1 band, along
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Figure 1. MT effects on IR spectra of water. (I) Lower: IR absorption of vacuum-distilled water (bottom) and the distilled water exposed to O2 (middle) of 98.2 Torr (broken and dotted) and 695 Torr (solid) and air of 1 atm (top) at 298 K. Solid and dotted lines, MT; broken line, NMT. Upper: difference absorption spectra between the MT and NMT spectra. (II) Magnetic field dependence of MT effects on IR absorption of aerated vacuum-distilled water of the constant thickness of 0.1 mm. (III) Difference absorption spectra between MT and NMT spectra in the regions of 2900 and 1050 cm-1. Magnetic field/T: blue, broken line, 3 T; red, solid line, 6 T. (IV) Variation of difference absorption intensity of the double peak as functions of oxygen concentration (left), magnetic field intensity (middle), and contact angle (right); open, 1085 cm-1; closed, 1045 cm-1.
20070 J. Phys. Chem. B, Vol. 110, No. 41, 2006
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Figure 2. Changes of Raman spectra of vacuum-distilled water and aerated vacuum-distilled water with MT at 298 K. (I) Difference Raman spectra between NMT and MT water films on a Pyrex glass plate measured with a Laser Raman spectrometer. (II) Magnetic field dependence of Raman spectra of aerated vacuum-distilled water treated by magnetic fields. The spectra were measured by excitation due to lights of 350, 400, and 500 nm with a spectrofluorometer. Any change in the spectra with MT disappeared at 3 days after MT, at which the contact angle recovered the initial value (∆θ ) 0°).
with 1400 and 1600 cm-1 bands.20 Therefore, we must examine the isotope effects on the peak positions. When the vacuum-distilled water was exposed to 18O2 (99 atomic%; ISOTEC, Inc.) of 634 Torr, 6T-MT(∆θ ) -5.0°; 18O ) made the doublet peak 1086 and 1044 cm-1 and the peaks 2 in the region of 2981 cm-1 (main) for 6T-MT(∆θ ) -6.4°; 16O ) shift to the doublet peak at 975 and 952 cm-1 and the 2 peaks at around 2850 cm-1 (main), as shown in Figure 3I. To confirm the peak shifts due to the isotope, we exposed the vacuum-distilled water to the gas mixture of 16O2 (345 Torr) and 18O2 (342 Torr), followed by 6T-MT(∆θ ) -5.5°). All of the peaks originating from 16O2 or 18O2 exposed water were found at the corresponding positions. The experimental peak positions of MFA water dissolving 18O2 seem to be much lower than those estimated from the mass ratio of 16O2 to 18O2 (e.g., 1025 and 984 cm-1 for the doublet peak), suggesting some interactions between an oxygen molecule and water molecules, such as electron transfer from triplet O2 to water cage.12 The doublet might result in O2 dimer formation, but preliminary ESR experiments gave no signal changes from aerated water after MT. Anyway, the new peaks must be attributed to certain species containing O2. However, D2O dissolving air did not bring about a peak shift of the new IR bands observed in the H2O systems but only peak
intensity reduction, although the contact angle also decreased. Figure 3II shows that the doublet peak appeared at 1082 ( 6 cm-1 and 1043 ( 6 cm-1, irrespective of the molar fraction of D2O (99.9%; Wako, Inc.) in aerated mixtures of light and heavy water, XH2O; 1(H2O) [MT(∆θ ) -6.6°)], 0.80 [MT(∆θ ) -6.7°)], 0.50 [MT(∆θ ) -6.4°)], 0.20 [MT(∆θ ) -5.5°)], and 0(D2O) [MT(∆θ ) -4.5°)]. The peak reduction suggests that water should interact with O2. If the species is oxygen clathrate-like hydrates, then a clathrate cage comprising D2O would suppress the vibrational modes of oxygen species, for example, through symmetry change from vibrational modes forgiven in light water to forbidden transition. Another possibility is that peak shift and peak broadening due to D2O may be too large to be detected. In both cases, D2O dissolving air can be “magnetized” by MT, but no new IR peaks may appear. We believe that the spectroscopic data proved that an MFA water is a real, but transient, material. The MFA water is obtained when a magnetic flux changes relatively across water dissolving oxygen, in which a transient structure, such as oxygen clathrate-like hydrates and promoted hydrogen-bonded networks, is formed and survives for a while. Then, the remaining questions are how to interact between oxygenated water and changing magnetic flux and how to propagate or maintain the MFA structure independent of thermal fluctuation. Srebrenik
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Figure 3. Isotope effects on IR spectra of oxygenated vacuum-distilled H2O and aerated D2O treated by magnetic field of 6 T at 298 K. (I) IR spectra of vacuum-distilled water dissolving 16O2 of 687 Torr (black, solid), a mixture of 16O2 (345 Torr) and 18O2 (342 Torr) (blue, dotted-broken), and 18O2 of 634 Torr (red, dotted) after MT. 6T-MT(∆θ ) -5.0°; 18O2) made the doublet peak 1086 and 1044 cm-1 and the peaks in the region of 2981 cm-1 (main) for 6T-MT(∆θ ) -6.4°; 16O2) shift to the doublet peak at 975 and 952 cm-1 and the peaks at around 2850 cm-1 (main). (II) D2O effects on IR spectrum of MFA water. The addition of D2O dissolving air to the MFA water (H2O) did not bring about a peak shift of the new IR bands observed in the H2O systems but only peak intensity reduction. Molar fraction of H2O, XH2O; 1(H2O) [MT(∆θ ) -6.6°)], 0.80 [MT(∆θ ) -6.7°)], 0.50 [MT(∆θ ) -6.4°)], 0.20 [MT(∆θ ) -5.5°)], and 0(D2O) [MT(∆θ ) -4.5°)].
20072 J. Phys. Chem. B, Vol. 110, No. 41, 2006 et al. proposed a quantum model for the magnetic effect on water clathrate Ca2+(H2O)4 in bulk water.21 The rotational behavior of H2O seems to closely resemble that of H2 (ortho-/ para-hydrogen) if the oxygen in a water molecule is bound to an adsorption site, for example, on solid surface16 and an O2 molecule, in which each water molecule has in practice only one rotational degree of freedom left. In our case, the clathrate would be replaced by (O2)m(H2O)n. The mechanism could give new scientific insight into water and oxygen clathrate hydrate and their magnetic interaction. Moreover, the MFA water may be regarded as a clean, safe solvent for preparing new materials or a reactant having new activity, different from normal water. For the sake of practical use of MFA water, we proposed an easy, rapid, cheep, and reproducible method for making an MFA water and the contact angle as a measure for progression of MT. The magnetic water treatment will be a promising technique because a magnetic field having a strong power of material transmission is an ecologically clean and soft energy and a compact device for MFA water could be constructed easily using permanent magnets. Using various MFA water having continuously controlled properties, industrial, agricultural, and materials processing will change extensively and foods, cosmetics, sanitation, and pasteurization would be improved. Acknowledgment. We are grateful to Prof. M. Takeda-Wada (Shinshu University) for THz spectroscopic experiments and Prof. K. Yamaguchi (Tokushima Science and Technology University) for mass-spectrometry experiments. This work was supported by Grant-in-Aid of Scientific Research for Priority Area (Area 767, No.15085204) from MEXT of Japan.
Letters References and Notes (1) Klassen, V. I. Magnetization of Water Systems (in Russian); Nauka: Moscow, 1982. (2) Szkatu-a, A.; Ba-anda, M.; Kopec´, M. Eur. J. Appl. Phys. 2002, 18, 41. (3) Ho-ysz, L.; Chibowski M.; Chibowski, E. Colloids Surf., A 2002, 208, 231. (4) Gehr, R.; Zhai, Z. A.; Finch, J. A.; Rao, S. R. Water Res. 1995, 29, 933. (5) Knez, S.; Pohar, C. J. Colloid Interface Sci. 2005, 281, 877. (6) Herzog, R. E.; Shi, Q.; Patil, J. N.; Katz, J. L. Langmuir 1989, 5, 861. (7) Tomba´cz, E.; Busch, K. W.; Busch, M. A. Colloid Polym. Sci, 1991, 269, 278. (8) Higashitani, K.; Kage, A.; Katamura, S.; Imai, K.; Hatade, S. J. Colloid Interface Sci. 1993, 156, 90. (9) Higashitani, K.; Iseri, H.; Okuhara, K.; Kage, A.; Hatade, S. J. Colloid Interface Sci. 1995, 172, 383. (10) Higashitani, K.; Oshitani, J. J. Colloid Interface Sci. 1998, 204, 363. (11) Otsuka, I.; Fukui, K.; Nakagawa, K.; Ozeki, S.; Nakayama, T.; Hosogi, T.; Saeki, C. J. JRICu (in Japanese) 2005, 44, 196. (12) Otsuka, I.; Ozeki, S. J. Phys. Chem. B 2006, 110, 1509. (13) Otsuka, I.; Saravanan, G..; Ozeki, S.; Nakayama, T.; Hosogi, T.; Saeki, C. J. JRICu (in Japanese) 2006, 45, 60. (14) Ozeki, S.; Wakai, C.; Ono, S. J. Phys. Chem. 1991, 95, 10557. (15) Ozeki, S.; Miyamoto, J.; Watanabe, T. Langmuir 1996, 12, 2115. (16) Ozeki, S.; Miyamoto, J.; Ono, S.; Wakai, C.; Watanabe, T. J. Phys. Chem. 1996, 100, 4205. (17) Hosoda, H.; Mori, H.; Sogoshi, N.; Nagasawa, A.; Nakabayashi, S. J. Phys. Chem. A 2004, 108, 1461. (18) Inaba, H.; Saitou, T.; Tozaki, K.; Hayashi, H. J. Appl. Phys. 2004, 96, 6127. (19) Iwasaka, M.; Ueno, S. Newsletter of InnoVatiVe Utilization of Strong Magnetic Fields 2004, 5, 9. (20) Polywater controversy boils over. Chem. Eng. News 1970, June 29, 7. (21) Srebrenik, S.; Nadiv, S.; Lin, I. J. Magn. Electron. Sep. 1993, 5, 71.
