Simple Coacervation of Sodium Polyphosphate Obtention

Abstract

Contrary to complex coacervation, simple one is not much quantitatively studied. Some authors examine polyphosphate coacervate properties such as thermal evolution 1, viscosity 2 or solubility in acid solutions 3. We experimentally induced sodium polyphosphate coacervation by univalent cation supply. This result seems to be inexplicable by present theories 4-5. So, we studied different parameters relating to coacervation and developed a theory of this phenomena for sodium polyphosphate solutions.

Spectroscopic Study and Local Coordination of Polyphosphate Colloidal Systems

“…[PP(H 2 O)Na] and [PP(H 2 O)Eu], rather than chemical formulas, are just schematic representations of the colloidal species present in the system. Therefore the pseudo-equilibrium represented by eq 3 is governed by the well-known equilibrium laws of thermodynamics and also by electrostatic interactions in the aqueous medium (DLVO theory) . Just by changing the solvent, for example, the situation could be dramatically changed.…”

“…The possibility of incorporation of different fillers opens a way to many different applications. , In general, the formation of these coacervates may be understood as a compromise involving different effects such as electrostatic repulsive and van der Waals attractive and repulsive solvation forces. A simple DLVO (Derjaguin−Landau−Verwey−Overbeek) electrostatic model has been used to explain the phenomenon …”

The coacervate route for polyphosphate glasses preparation

“…Sodium polyphosphate, (NaPO 3 ) n , also known as Graham's salt, is a water-soluble glassy product obtained from the melting of sodium dihydrogen phosphate, NaH 2 PO 4 [1]. The polymeric structure of Graham's salt is built by large polyphosphate chains, with reported average lengths attaining up to 30 PO 3 units [1][2][3][4], leading to the general formula (NaPO 3 ) n . Changes in the chemical properties of the aqueous (NaPO 3 ) n solution, such as addition of electrolytes or changes in the dielectric constant, e.g.…”

“…Changes in the chemical properties of the aqueous (NaPO 3 ) n solution, such as addition of electrolytes or changes in the dielectric constant, e.g. by the addition of methanol, lead to the coacervation process through the formation of colloidal vesicles followed by their aggregation, leading to liquid-liquid phase separation, being the coacervate the denser phase [1][2][3][4][5]. Drying procedures of the coacervates in silica gel vacuum desiccator lead to solid transparent glassy materials.…”

Characterization of polyphosphate glasses preparation using CRTA

“…Simple coacervation of polyphosphates [7] is a kind of flocculation which leads to a compound containing 50% of water and 50% of dry sul~stances, in weight. It is obtained when sodium polyphosphate (Graham's salt) and cationic species are together in solution, for specific concentrations.…”