Inhibition of calcium and magnesium carbonate crystallization with sodium polyacrylate

Abstract

It is known that when water are used for technological purposes, in circulating water supply systems of enterprises as a coolant during continuous heating and cooling, the formation of insoluble precipitates, most often calcium carbonates, occurs on the walls of heat exchangers, which leads to a large number of problems, even production can be stopped for cleaning equipment. To prevent the formation of salts, it is necessary to use precipitation inhibitors. Sodium polyacrylate was investigated as a precipitation inhibitor. The composition, morphology and IR spectra of calcium carbonate precipitate obtained in the absence and in the presence of sodium polyacrylate were studied. It was established that the effect of sodium polyacrylate on the mechanism of crystallization of carbonate sediment depends on the pH of the initial solution. The results of IR spectroscopy, X-ray diffraction analysis and images obtained by electron microscopy indicate the participation of polymer molecules in the formation of the crystalline structure of the carbonate precipitate.

Polysaccharides as Effective and Environmentally Friendly Inhibitors of Scale Deposition from Aqueous Solutions in Technological Processes

“…The influence of alkaline earth metal ions present in the extracted water on the crystallization of calcium carbonate is of practical importance for understanding the mechanism of sediment formation. Thus, the influence of the Mg 2+ ion concentration and temperature on the crystal structure of CaCO 3 was shown in [ 64 , 65 ]. It was found that the composition of polymorphic calcium carbonate formed during precipitation was determined by both the pH value and the duration of the crystallization process [ 64 ].…”

“…Thus, the influence of the Mg 2+ ion concentration and temperature on the crystal structure of CaCO 3 was shown in [ 64 , 65 ]. It was found that the composition of polymorphic calcium carbonate formed during precipitation was determined by both the pH value and the duration of the crystallization process [ 64 ]. At t = 80 °C in the presence of Mg 2+ ions, the main polymorphic modifications of calcium carbonate were aragonite and magnesian calcite, and the content of aragonite increased as the duration of the crystallization process increased.…”

“…The nature of the interaction between NaCMC and the calcium scale is quite complex. The main reason for the influence of NaCMC on the crystallization of calcium carbonate is likely the specific adsorption of NaCMC on the forming surfaces of calcium carbonate and sulfate, both due to the electrostatic interaction of ionized carboxyl groups with Ca 2+ ions located on the crystal surface, and the coordination and hydrogen bonds between oxygen atoms and OH groups of D-glucose fragments [ 23 , 64 , 75 , 122 ]. This interaction leads to the formation of polymorphic forms without pronounced morphological features and changes in the size of calcium carbonate particles [ 132 , 133 ].…”