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COMPARISON
OF THE EXTRACTION EFFICIENCY OF SOME METAL CATIONS BY CROWN ETHERS
Ranka KubiCek,
Jozo Budimir, Hatidza Pasalic, Snjezana Maric, and
Amira Cipurkovic
Department
of Chemistry, Faculty of Technology, University of Tuzla, 75000 Tuzla, Bosnia
and Herzegovina
The effect of crown ethers on
extraction of metal cations: Pb(II), Fe(III), Hg(II), Cu(II) and Cd(II) was
investigated. Extraction was carried out on model systems composed of metal
cation, water, anion for ion association formation, crown ether and organic
solvent. Crown ethers: [18]crown-6 (18C6), dicyclohexano-[18]crown-6
(DC18C6), dibenzo-[18]crown-6 (DB18C6), hexathia-[18]crown-6 (18S6), hexaaza-[18]crown-6 (18N6) and organic solvents benzene, chloroform
and dichloromethane were used.
The extraction results showed
that:
·
The order of the
extractability of Pb(II) in water/benzene system was: DC18C6 < 18C6 <
DB18C6. The greatest extraction efficiency, obtained with DB18C6, amounting
to 65.36 %.
·
Cu(II) and
Cd(II) ions were not extracted by above mentioned crown ethers in extraction
systems water/benzene.
·
Fe(III) ions
were extracted with great efficiency in water/chloroform system by using
crown ethers containing oxygen as heteroatom at corresponding pH of HCl
solution. The greatest efficiencies, ranging from 95-99%, were achieved at
HCl concentrations: 6 mol/dm3 with 18C6, 5 mol/dm3 with
DB18C6, and 4 mol/dm3 with
DC18C6.
·
Hg(II) ions
showed different extraction efficiency in extraction systems water/chloroform
and water/dichloromethane, while the order for crown ethers efficiency was:
18S6 > 18C6 > 18N6. Extraction efficiency obtained with crown ether
18S6 was 90.5% in the system containing
chloroform and 86% in the
dichloromethane system.
M.V. Alfimov et
al., J. Am. Chem. Soc. 121 (1999) 4992.
Y. Takeda, Ch.
Takagi, Sh. Nakai, K. Endo, Sh. Katsua, Talanta 48 (1999) 559.
S. Katsua, F.
Tsuchya, Y. Takeda, Talanta 51 (2000) 637.
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