The Extraction of Zirconium(IV) from Sulfuric Acid Solutions with High-Molecular Weight Quaternary Ammonium Compound

Abstract

The extraction of zirconium sulfate in aqueous sulfuric acid solutionswith trioctylmethylammonium chloride (Aliquat-336; R₃R'NC1) in organic solvents has been investigated under different conditions. In addition, the organic phases extracted sulfuric acid and zirconium sulfate were examined by IR and NMR spectroscopies. It has been found that Aliquat-336 extracts zirconium(IV) from sulfuric acid solutions according to the following ion-exchange reactions.
i) The extraction of sulfuric acid is at first carried out through the equilibria, SO₄^2-(aq) + 2 R₃R'NCl(org) ↔ (R₃R'N)₂SO₄(org) + 2Cl^-(aq) (R₃R'N)₂SO₄(org) + H⁺(aq) + HSO₄-(aq) ↔ 2R₃R'NHSO₄(org)
ii) The extraction of zirconium is expressed as the equilibri um reaction Zr(SO₄)₃^2-(aq) + 2xR₃R'NHSO₄(org) + (1-x) (R₃R'N)₂SO₄(org) ↔ (R₄R'N)₂[Zr(SO₄)₃](org) + xH₂SO₄(aq ) + SO₄^2-(aq) x=[R₂R'NHSO₄]/{2[(R₃R'N)₂SO₄] + [R₄R'NHSO₄]}
Moreover, the hydrolyzed species (R₃R'N) [ZrO (OH) (SO₄)] is formed when zirconium is further extracted in an organic phase.