Adsorption And Ion-exchange From Aqueous Solutions Under Magnetic Field Influence
Adsorption and Ion-exchange from Aqueous Solutions under magnetic Field Influence
B. A. Baran
Technological University of Podillya, Khmelnitskiy, Ukraine
The magnetic field action mechanism on aqueous solutions has not been completely cleared up yet. However, according to a lot of data it is connected with the hydration of particles (molecules or ions) dissolved in water. The hydration nature affects the main properties of the aqueous solutions, i.e. their thickness, solubility, diffusion coefficient of a soluble substance, electric conduction, etc.
Evidently the phase of hydration greatly influences the process of sorption either ion-changing or molecular ones. Mobility and chemical activity of the molecules depend on the quantity of hydrate sheath, depending on polarizating action of an ion and quantity of dipole moment of a molecule the metastable aquacomplexes of various sizes can be formed.
By means of NMR it was determined that after magnetic field action the molecules of water are monomerizel, becom more movable. Thermographic analyses has showed that under magnetic field influence the boiling point of water somewhat decreases and water heat conduction increases. Under these conditions evaporations heat decreases by 12%. That means that hydrogen bonds energy among water molecules decreases. In this case the "structure" temperature of the solution increases. Thus the magnetic field affects thase physical and chemical processes in acqueous solutins in which hydrogen bonds are of dominant significance.
5-25% increase of dye sorption quantity under the influence of magnetic field on textile materials takes place sorption velocity of some dyes on activated carbon can increase by 2-2.4 times. It is explained by the fact that in contradistinction to flat surfaces the movement particles in micropores depends on hydrate sheats sizes. Besides the dyes molecules have hydrophilic polar groups and hydrofobic weak polar ones. With various hydrogen bonds energies among them and water molecules. Identically magnetic field influ-
ences effectively the velocity of ion exchange only by means of microporic sorbents. The solution temperature increase results in increase of ion hydration heat at the expence of decrease of the energy which is necessary for destruction of the initial water structure while forming hydrate complexes. In this case, such role is played by "structure" temperature. Strengthening of ions hydrate sheaths can impede their movement in the sorbents micropores. The ability of ions to be hydrated is characterized by the relation of their charges to radii as well as the tendency to form aquacomplex. That\’s why the correlation between magnetic field effect and ions hydration heats is observed. The increase of water moleculs movement under the ions mobility, increase velocity of their sorption. That also depends on the type of sorbent. The natural clinoptilolyt in Na-form sorbs Ba2+ ions from 0.01 N solutions BaCl2 both under ordinary conditions and at the action on magnetic fields. It is conditioned by small ion-exchanging capacity of zeolite and small size of its pores.
Sorption of Ba2+ ions on zeolite takes place with moderate velocity and a great effect of magnetic field is observed- after its acting on BaCl2 solution the sorption process slows down. The quantity of this effect depends on the exchange phase: while the phase increases the effect gradually decreases.
Slowing down of Ba2+ ions sorption can be explained by the fact that owing to weakening of aqueous bonds energy among molecules of water the hydration heat increases: the energy necessary for initial water structure breaking and including the water molecules in coordinate ions sphere, decreases. While Ba2+ ions exchanging on NaX zeolite, the effect of magnetic field is not observed. A and X zeolites are different by crystal structure, in particular by the pores size.
In A type zeolite the size of the entrance "window" is 0.43 nm аnd in NaX type one the size of the entrance \’\'window\’\’ is 0.7 nm, that\’s why in the latter case small changes of Ba2+ ion hydrate sheath don\’t affect their movement within pores of the zeolite.
Ion-exchange resign has a net structure which doesn\’t have true pores (continuous and gel structure), that\’s why the character of magnetic field influence on ion exchange in such a resign somewhat different that the character of magnetic field influence of zeolite with crystalline structure.
When ordinary water is substitudes by hevy one (D2O) the magnetic field effect while Ba2+ ions sorbtion from 0.02 N of BaCl2 solution under the same conditions has not been observed. That can be connected with nuclear spin of ordinary hydrogen (H) and deuterium (D) which is different in both cases.
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