Selective extraction of zinc(II) over iron(II) from spent hydrochloric acid pickling effluents by liquid-liquid extraction

J Hazard Mater. 2008 Feb 11;150(3):669-78. doi: 10.1016/j.jhazmat.2007.05.019. Epub 2007 May 13.

Abstract

The selective removal of zinc(II) over iron(II) by liquid-liquid extraction from spent hydrochloric acid pickling effluents produced by the zinc hot-dip galvanizing industry was studied at room temperature. Two distinct effluents were investigated: effluent 1 containing 70.2g/L of Zn, 92.2g/L of Fe and pH 0.6, and effluent 2 containing 33.9 g/L of Zn, 203.9g/L of Fe and 2M HCl. The following extractants were compared: TBP (tri-n-butyl phosphate), Cyanex 272 [bis(2,4,4-trimethylpentyl)phosphinic acid], Cyanex 301 [bis(2,4,4-trimethylpentyl) dithiophosphinic acid] and Cyanex 302 [bis(2,4,4-trimethylpentyl) monothiophosphinic acid]. The best separation results were obtained for extractants TBP and Cyanex 301. Around 92.5% of zinc and 11.2% of iron were extracted from effluent 1 in one single contact using 100% (v/v) of TBP. With Cyanex 301, around 80-95% of zinc and less than 10% of iron were extracted from effluent 2 at pH 0.3-1.0. For Cyanex 272, the highest extraction yield for zinc (70% of zinc with 20% of iron extraction) was found at pH 2.4. Cyanex 302 presented low metal extraction levels (below 10%) and slow phase disengagement characteristics. Reactions for the extraction of zinc with TBP and Cyanex 301 from hydrochloric acid solution were proposed.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Hydrochloric Acid / chemistry*
  • Industrial Waste
  • Iron / chemistry*
  • Metallurgy
  • Organophosphates / chemistry
  • Organothiophosphorus Compounds / chemistry
  • Phosphinic Acids / chemistry
  • Waste Disposal, Fluid / methods*
  • Water Pollutants, Chemical / chemistry*
  • Zinc / chemistry*

Substances

  • Cyanex 272
  • Cyanex 302
  • Industrial Waste
  • Organophosphates
  • Organothiophosphorus Compounds
  • Phosphinic Acids
  • Water Pollutants, Chemical
  • bis(2,4,4-trimethylpentyl)dithiophosphinic acid
  • tributyl phosphate
  • Iron
  • Zinc
  • Hydrochloric Acid