Magnetic Field Effect on Water Surface Tension in Aspect of Glass and Mica Wettability

Abstract

It was reported in many papers that the magnetic field (MF) affects properties of water, and, among others, its surface tension. Thus, it should be reflected in changes of the wetting contact angle of a water droplet deposited on the solid surface. In this study, the water contact angles were measured on the glass and mica surface. The water was first exposed to the static magnetic field (MF) (15 mT or 0.27 T) for 1, 5, and 10 min under dynamic conditions. Then applying the van Oss et al. approach (LWAB), it was found that the MF effect is reflected in the changes of the calculated acid-base components of the solids, especially the electron donor parameter. However, the total surface free energy of the solids remained practically unchanged. Moreover, the apparent surface free energy of the solids calculated from the water contact angle hysteresis (CAH), i.e., the difference between the advancing and receding contact angles, changes in the same way as the electron donor parameter does. Since the solid surfaces were not magnetically treated, the acid-base components, which are mainly results from hydrogen bonding interactions, may be indirect evidence of the water structure changed by the MF action. All of the mentioned changes are greater for the glass than for a more hydrophilic mica surface and depend upon the time of MF exposure and its strength. The magnetic field effect on the changes of the surface-free energy parameters for the mica and glass is opposite what may be due to the difference in the surface hydrophilicity. A “magnetic memory” effect was also found. The effect of MF on the water surface tension depends on the circulation time. It increases with the field duration. Moreover, the changes in the work of water adhesion indicate the possibility of solid surface wettability changes by the external MF water treatment. However, these are preliminary results that need further confirmation by other techniques.