Features of Magnetic Treatment of Calcium Bicarbonate Waters
- PDF / 1,296,805 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 114 Downloads / 178 Views
ICAL CHEMISTRY OF WATER TREATMENT PROCESSES
Features of Magnetic Treatment of Calcium Bicarbonate Waters R. D. Chebotarevaa, *, A. V. Nanievaa, and S. V. Remeza a
Dumansky Institute of Colloid and Water Chemistry, National Academy of Sciences of Ukraine, Kiev, 03142 Ukraine *e-mail: [email protected] Received August 7, 2017; revised May 21, 2020; accepted June 18, 2020
Abstract—It was shown that magnetic treatment is more efficient for bicarbonate water containing free carbon dioxide at subequilibrium concentration. After removing the excess of carbon dioxide by purging with an inert gas or by long boiling, a CaCO3 precipitate forms, which mainly consists of acicular aragonite. This is likely to be due to the fact that the water degassing disturbs the spatial structure of water and brings it to a metastable state, which is more sensitive to the action of the magnetic field. Magnetic treatment of water favors the directional crystallization of the precipitate of the calcium carbonate precipitate in the form of acicular aragonite mainly in the bulk of the solution, rather than on the surface of the vessel (heating pipe). Supersaturation of water with bicarbonate ions affects similarly. Magnetization of water, as well as its degassing, boiling, or other physical actions, brings the water structure to a metastable state, in which smaller clusters break up and then coalesce into larger ones. Obviously, this leads to the liberation of oxygen dissolved in water, which was previously bound to water molecules; the oxygen concentration in water after magnetic treatment increases. The metastable state of water that is caused by the action of the magnetic field forms for a time of half an hour to 60 min, and then the water structure is restored to the initial state. Keywords: cluster structure of water, calcium carbonate, magnetic treatment of water DOI: 10.3103/S1063455X20050057
INTRODUCTION One of the challenges of industrial water treatment is hardness scaling on the surface of water-heating equipment [1]. This is due to the fact that a significant part of the impurities in natural water is ions of the carbonate buffer system (Ca2+, HCO3− , CO32 − , CO2), which maintain carbon dioxide equilibrium of water with the environment and, under certain conditions, can form a poorly soluble precipitate of calcium carbonate. The dissolution of atmospheric carbon dioxide in water gives slightly dissociated carbonic acid: CO2 + H2O ↔ H2CO3, which is in dynamic equilibrium with bicarbonate ions occurring in water as salts with the cations Са, Mg, Na, K, and others:
2Са (HCO3 )2 ↔ СаCO3 + CO2 + H2O. If the content of free carbonic acid in water is lower than that necessary for maintaining equilibrium, then such a solution is supersaturated with calcium carbonate (unstable state), which can precipitate from the solution under the action of external factors: a temperature increase; the presence of seeds (crystallization nuclei) in water; or a physical action: intense stirring, magnetization, sonication, etc. [2–5]. The investigation of the m
Data Loading...
