Open AccessSynthesis of Mn(II)-containing paratungstate B from aqueous solutions acidified by acetic acid
Author(s) -
Stus Vasyl'
Publication year - 2021
Publication title -
voprosy himii i himičeskoj tehnologii/voprosy himii i himičeskoj tehnologii
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.278
H-Index - 7
eISSN - 2413-7987
pISSN - 0321-4095
DOI - 10.32434/0321-4095-2021-135-2-39-48
Subject(s) - chemistry , aqueous solution , potentiometric titration , equilibrium constant , inorganic chemistry , acetic acid , protonation , titration , sodium tungstate , electrolyte , ion , organic chemistry , electrode , tungsten
The method of pH-potentiometric titration and mathematical simulation were used to study the equilibrium processes in aqueous solutions of the WO42––CH3COOH–H2O system in the acidity range Z=(CH3COOH)/(Na2WO4)=0.8–1.7 at СW=0.01 mol L–1 and T=2980.1 K, a constant ionic strength being maintained by sodium nitrate as a background electrolyte ((NaNO3)=0.10 mol L–1). We developed the models of polyoxotungstate anions formation and the equilibrium transformation processes, which adequately describe experimental pH vs. Z dependences. It was found that acetic acid using to create the solution acidity that is necessary for the formation of isopoly tungstate anion contributes only to the formation of protonated paratungstate B anions Нх[W12O40(ОН)2](10–х)– (where x=0–4). We calculated the logarithms of the concentration equilibrium constants of the polyanion formation and plotted the distribution diagrams. Double sodium-manganese(II) paratungstate B Na8(H2O)28Mn(H2O)2[H2W12O42]4H2O was synthesized at Z=1.00 to confirm the results of the mathematical modeling. The chemical composition of the prepared salt was established by chemical elemental analysis, thermal analysis, FTIR spectroscopy, and single crystal X-ray analysis. The stepwise process of salt dehydration was studied by means of differential thermal analysis.