Effective one-step removal-inertization of hazardous metals (Cd and Hg) by environmental friendly reagents

• The use of a safe reagent for oxidizing/complexing elemental cadmium and mercury.
• High yield one-step dissolution-sequestration of toxic metals in mild conditions.
• New complexes of cadmium and mercury with cyclic dithioxamides and iodine.
• Potential application in leaching of toxic metals from Hi-Tech waste.

[HMe2pipdt]I3 (Me2pipdt = N,N′-dimethyl-piperazine-2,3-dithione, 1) is capable to quantitatively dissolve elemental Cd and Hg to produce in a one-step reaction the [CdI(Me2pipdt)2]I3 (2) and [HgI2(Me2pipdt)] (3) complexes. Crystals of 2 and 3 have been structurally characterized and crystallize in the P-1 and C2/c space group respectively. In 2 Cd(II) shows a coordination geometry intermediate between the square pyramidal and the trigonal bipyramidal. In 3 Hg(II) adopts a distorted tetrahedral geometry which involves a S,S chelating ligand and two iodine atoms in the coordination sphere. Vibrational spectroscopy findings are in agreement with structural results showing in the far-infrared region to be a diagnostic probe in recognizing triiodides.

The non-cytotoxic reagent [HMe2pipdt]I3 (Me2pipdt = N,N′-dimethyl-piperazine-2,3-dithione) has shown to be effective in removing and inerting quantitatively elemental cadmium and mercury, very toxic metals, under mild conditions, giving in a one-step reaction the [Cd(Me2pipdt)2I]I3 and [Hg(Me2pipdt)I2] complexes, respectively.Figure optionsDownload as PowerPoint slide