Adducts Formation of Various Heavy Metal Thiocyanato-N Complexes with Nonionic Surfactantt

Abstract

On adding a small amount of Triton X-100, a nonionic surfactant to an aqueous solution of some divalent or trivalent metal ions containing potassium thiocyanate in excess, various colored tarry gels deposited. The colors were as follows: Ti(III1) violet, VOID yellow brown, Cr(III) purple, Fe(III) deep red, Fe(II) white, Co(II) deep blue, Cu(II) dark brown, and Zn(I0 white. Scan), Mn(II), and Ni(II) ions did not form such gels. These gels w ere stoichiometric adduct such as K₂[M^II(NCS)₅]⋅2Triton, and K₂[M^III(NCS)₅]⋅2Triton. The compositions remained essentially constant on preparing with various concentrations of potassium thiocyanate and Triton. Although such higher thiocyanato-N complexes would exist not so many in the aqueous solution, Triton might selectively bind to the complex of higher order, and the equilibria of complex formation would be forced to move. The recovery of metal ions remaining in the supernatant liquid was minimized when the Triton addition was conducted at a molar ratio of Triton/metal ion =2. Qualitative tests on the other heavy metals made it clear that 30 metal ions produced similar gels, but 20 metal ions did not. The nature of alkali-metal ion or alkaline earth-metal ion as a counter ion of thiocyanate had the serious effect on the gel yield. t Adducts of Heavy Metal Thiocyanato-N Complexes with Nonionic Surfactant. II.