Redox Equilibria in the System Fe(OH)3(H2SO4)-Na2SO3-H2O Involving Precipitation of Iron(II) Sulfite as a Fe2O3 Precursor

Experimental data on the equilibria Fe²⁺/Fe³⁺ and SO₃ ²⁻/SO₄ ²⁻ in the system Fe(OH)₃(H₂SO₄)-Na₂SO₃-H₂O are presented. The quantitative relations between the reduction of Fe(III) and the precipitation of FeSO₃·2.5H₂O as a Fe₂O₃ precursor have considered graphically.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1, 2005, pp. 41–44.Original Russian Text Copyright © 2005 by Vasekha, Motov.     

Synthesis of nanoscale nickel(II) and cobalt(II) sulfides

Ranges of stability and regions of the stoichiometric stability of sulfide phases of nickel(II) and cobalt(II) are determined in water–salt solutions. Regions of the homogeneity of NiS and CoS monosulfides are considered. The composition of a microemulsion used as a nanoreactor for synthesizing sulfides is determined, and its phase diagram is plotted. The results from estimating the size of the obtained nanocrystals are presented.     

FeCl2-Na2SO3-H2O system as a basis for recovery of iron(II) sulfite from solution

The FeCl₂-Na₂SO₃-H₂O system was studied along seven sections with the molar ratios Na₂SO₃: FeCl₂ = 5: 1, 5: 2, 5: 3, 5: 4, 5: 5, 5: 10, and 5: 15, including six points on each section where pH ranges from 1.5 to 4.0 in 0.5 steps. Equal-undersedimentation lines for cations and anions were plotted. The iron(II) system forms sodium ferrisulfites NaFe₅O_0.5(SO₃)₅ · 5H₂O, NaHFe₅(SO₃)₆ · 5H₂O, Na₂Fe₅(SO₃)₆ · 4H₂O, and NaHFe₂(SO₃)₃; the iron(III) system forms Na₂Fe₆(SO₃)₇ · 10H₂O. The regions where these compounds sediment were demarcated, and their characterizations were carried out.     

Sulfite solutions for conversion of iron hydrate wastes formed at copper-nickel industries

Possibility was examined of using spent solutions of sulfur dioxide gas sorbents, together with sodium sulfite and pyrosulfite, for conversion of iron hydrate wastes produced by copper-nickel industries to red iron oxide pigment.     

Synthesis and properties of double copper(I)–nickel(II) sulfite

Pourbaix diagrams of Cu–H₂SO4–H₂O and Ni–H₂SO₄–H₂O systems have been refined, and stability regions of the sulfite phases have been determined. State diagrams of double copper(I)–copper(II) and copper(I)–nickel(II) sulfites have been constructed. Double copper(I)–nickel(II) sulfite has been isolated from aqueous solutions saturated with sulfur dioxide. The solutions at different ratios of the metals have been studied by spectrophotometry; the isolated double sulfite has been studied by X-ray diffraction, IR spectroscopy, dispersion analysis, and thermal analysis. Fundamentals of thermodynamic prognostication of the Cu₂SO₃·MSO₃ double sulfites synthesis have been elaborated.