Abstract: MATH/CHEM/COMP 2002, Dubrovnik, June 24-29, 2002
COMPARISON OF THE EXTRACTION EFFICIENCY OF SOME METAL CATIONS BY CROWN ETHERS
Ranka KubiCek, Jozo Budimir, Hatidza Pasalic, Snjezana Maric, and
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: crown-6 (18C6), dicyclohexano-crown-6 (DC18C6), dibenzo-crown-6 (DB18C6), hexathia-crown-6 (18S6), hexaaza-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.
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