Short communication Kurze Mitteilung

Ligand exchange separation of some transition metal ions and preconcentration of silver(I) and mercury(II) on alumina-immobilized m-aminobenzenesulphonic acid columns

Dhruv Kumar Singh and Rishi Raj Bhatnagar*

Department of Chemistry, Harcourt Butler Technological Institute, Kanpur-208 002, India

Ligandenaustauseh-Trennung einiger I:lbergangsmetaU-Ionen und Anreieherung yon Silber(I) und Quecksilber(II) an Aluminiumoxid-immobilisierten m-Aminobenzolsuffonsiiure- Siiulen

Use of immobilized ligands on solid supports for separation and preconcentration of metal ions has received considerable attention in recent years [1, 2]. The high sorption capacity of basic alumina for m-aminobenzenesulphonic acid has been utilized for the separation of metal ions on the basis of ligand exchange. The basic aluminium oxide (100-150 mesh) washed with hot water was sorbed with m-aminobenzenesulphonic acid (0.5% for 24 h). The rate of sorption studies for Cu 2+, Hg z+ and Ag + revealed that equilibrium was attained within 20 rain only in case of treated alumina due to the chelating agent,

Table 1. Kd-values a of metal ions

Metal Demineral- pH 4 pH 6 pH 8 pH 10 ions ized water

Zn 2 + 23.6 12.0 24.0 20.0 16.7 Cd z+ 36.5 18.8 50.0 51,8 55.6 Hg z+ 220.0 218,0 233.3 - - Cu 2 + 48.0 52.0 46.2 21.2 3.5 Ni 2 + 23.0 7.8 43.2 41.8 36.0 Mn 2+ 33.2 13,3 27.5 30.0 - Fe z+ 198.5 96.5 105.0 - - Co z + 4t.2 14.2 46.7 -- 140.0 Zr ~+ 50.0 41.2 45.5 48.5 - Cr 3+ 30.0 20.0 26.3 38.5 56.3 V 5+ 36.3 16.7 20.6 25.7 36.6 Mo 6+ 130.0 43.2 65.8 46.0 27.8 Ag + 380.0 381.6 390.0 - 13.2 Ru s + 550.0 372.7 371.4 - 300.0 Pt ~+ 54.5 48.9 73.3 -- 16.0 Os s+ 237.8 228.5 241.4 - -

" K a = Amount of metal ion in exchanger phase (g- l)

Amount of metal ions in solution phase (cm- 3)

* Present address: Department of Chemistry, Christ Church College, Kanpur-208 001, India Offprint requests to." R. R. Bhatnagar at Christ Church College

whilst 2 h were required for untreated alumina. The results of distribution studies of 16 metal ions in demineralised water and different pH-systems (4 -10 ) are presented in Table 1. The treated exchanger has been found to be selective for Ag +, Hg z+, Ru s + and Os s +. The reason for selective sorption and desorp- tion of certain metal ions can be attributed to the large differ- ences in stability constants of metal-m-aminobenzenesulphonic acid complexes at certain pH-values. The elution is based on the stability constant of metal-eluting ligand (eluent) complex. The quantitative separations achieved experimentally (Table 2) include Ni z + -Fe 3 +, Zn 2 +-Ag +, Zn 2 +-Hg z +, Cr 3 +-Fe a +, Pt 4 +- Ru s + and Cu z +-Ag +. The recovery of Ag + (108- 431 gg) and Hg 2 + (200- 401 gg) from dilute solutions in presence of Zn / +, Cd z +, Ni 2 +, Co z + and Cr 3 + (2 mg each) has also been studied at pH 4.

Table 2. Separation of metal ions on treated alumina columns

Sample Mixture Eluent Eluate Amount Amount Percen- (ml) loaded recovered tage

(gg) (gg) error

1 Ni z + A 30 293,6 293.0 0.20 Fe 3+ B 40 285,6 286.1 0.45

2 Zn z + A 30 327.0 328.6 0.48 Ag § C 50 535.0 533.8 0.22

3 Zn z + A 30 325.2 323.0 0.67 Hg 2 + D 50 401.2 400.0 0.29

4 Cr ~+ A 30 260.8 261,4 0.22 Fe 3 + B 40 285.6 280.0 1.96

5 Pt a+ C 40 390.2 388.0 0.46 Ru 8+ E 50 400.2 395,4 1.10

6 Cu 2+ F 30 460.8 458.2 0.56 Ag + C 50 350.0 352.0 0.57

Abbreviations used: A 0.01 tool/1 HCI; B 0.1 tool/1 sodium citrate; C 2mol/l NH3; D 0.01 tool/1 EDTA; E 0.5tool/1 thiourea; F0.1 mol/1 NH3

Acknowledgements. The authors are thankful to Prof. A.K. Vasishtha, Director and Professor R.S. Tewari, Head, Depart- ment of Chemistry, Hartcourt Butler Technological Institute, Kanpur-208 002, India, for providing research facilities. U.G.C., New Delhi is also acknowledged for financial assistance.

References

1. Watanesk S, Schilt AA (1986) Talanta 33:895 2. Singh DK, Bhatnagar RR (1986) Fresenius Z Anal Chem

325:195

Received August 15, 1987

Fresenius Z Anal Chem (t988) 329:878 �9 Springer-Verlag 1988

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