Heavy Metal removal by using liquid liquid extraction

Abstract

Toxic metals are mostly present in the environment due to natural phenomenon and human activities as well.
Exposure of these non-essential elements in the environment causes severe effects. They are known to cause problems
in humans as well as in aquatic life [1]. Solvent extraction is recommended as a suitable method for the removal of
heavy metals from the wastewaters of the chemical and electronic industries. Common extractent are organic
compounds with molecular mass 200-450, almost insoluble in water (5-50 ppm), that selectively extract metals from
aqueous solutions. On the basis of data from the literature, the extraction conditions are reviewed for the metals that
cause problems in waste waters. The extraction conditions are understood to mean the type of extractent, anion present
in the aqueous phase, and pH [2]. The extraction behaviours of Zn (II) and Cu (II) from perchlorate media have been
investigated using bis-2-ethylhexyl phosphoric acid (D2EHPA) and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl
ester, (PC-88A) in toluene. The extraction of Zn (II) was found to be quantitative in the pH range 2.5 to 3.0 and 3.0 to
4.0 D2EHPA and PC-88A in toluene, respectively, while Cu (II) was extracted quantitatively in the pH range 6.0 to 8.0
and 5.5 to 7.0 D2EHPA and PC-88A in toluene, respectively. Zn (II) was stripped with HCl, while Cu (II) with H2SO4
and HNO3 from the organic phase containing D2EHPA and PC-88A, respectively [3].