EXTRACTION OF COPPER, ZINC AND IRONFROM HYDROCHLORIC ACID SOLUTIONS BY MEANS OF

BIFUNCTIONAL EXTRACTANT KELEX 100

Svetlana Zhivkova and George Kyuchoukov

Institute of Chemical EngineeringBulgarian Academy of Sciences

Sofia , Bulgaria

INTRODUCTION

The recovery of valuable materials from waste industrial solutions is an important component of the environmentally benign technologies. Liquid-liquid extraction aims at removal and separation of components in aqueous feed solutions. The selectivity removal of copper, zinc and iron from hydrochloric acid solutions by means of solvent extraction has been studied. The metal anion complexes are extracted from hydrochloric acid medium. The individual extraction of copper, zinc, iron, and simultaneous extraction of the two ion pairs Cu – Zn and Zn – Fe has been studied

The AIM of the work is to investigate the possibility for effective removal of copper, zinc and iron from hydrochloric acid solutions by means of solvent extraction using bifunctional extractant Kelex 100.

RESULTS

The studies on the removal of copper, zinc and iron from hydrochloric acid solutions show that with the increase of the concentration of hydrochloric acid and chloride anions, the extraction of both the copper and the zinc decreases, the zinc being better extracted than copper. Iron extraction increases with the concentration of hydrochloric acid and chloride anions, because Kelex 100 protonates in higher degree and extracts better the anion complex of 3-valent iron.

In the simultaneous extraction of zinc and iron - the extraction isotherm for copper has an ascending part beginning from the highest concentration in the raffinate as a result of the gradual zinc consumption and a descending part begining when the concentration of zinc in the raffinate is less 0.01 M. Zinc was predominantly extracted from solutions containing zinc and copper together.

In the simultaneous extraction of zinc and iron - much better extraction of zinc then iron has been registered - the complete recovery of zinc from the feed solution is performed in 4 extraction stages. The extraction isotherm for iron is shown on the table. It has been found that considerable extraction of iron takes place only in the first extraction stage.

EXPERIMENTAL

All experiments are carried out with model aqueous solutions.The content of hydrochloric acid and chloride anions was keep constant and metal concentracion is: For individual presence of copper: [Cu2+]=0.9652 M (61.33 g/l), [H+]=1.814 M, [Cl-]=7.359 M;For individual presence of zinc : [Zn2+]=0.9537 M (62.44g/l), [H+]=1.795 M, [Cl-]=7.496 M;For individual presence of iron: [Fe tot]=1.131 M (63.13g/l), [H+]=6.697 M, [Cl-]=7.371 M.For pair copper – zinc simultaneous presence of both metals in initial solution the concentration is:[Cu2+]=0.9592 M, [Zn2+]=0.3534 M, [H+]=1.834 M, [Cl-]=7.243 M.For pair iron – zinc simultaneous presence of both metals in initial solution the concentration is:[Fetot]=0.9643 M, [Zn2+]=0.3858 g/l, [H+]=2.949 M, [Cl-]=4.043 M.

The composition of the organic phase is:20 v/v % Kelex 100 as extractant, 15 v/v % 1-Octanol as modifier and 65 v/v % kerosene as diluent.The commercial bifunctional agent Kelex 100® with his active compound Alkyl-8-hydroxyquinolineis a typical bifunctional extractant.Deprotonated and conditioning extractant were used.

Kelex 100®:

NR

O H

C 2 H 5

|R = — C H — ( C H 2 ) 2 — C H — ( C H 2 ) 3 — C H 3

| C H 3

Figure 1Коефициент на разпределение на метала като функция

на киселинноста, from initials solutions:[Cu2+]=0.9652 M (61.33 g/l), [H+]=1.814 M, [Cl-]=7.359 M;[Zn2+]=0.9537 M (62.44g/l), [H+]=1.795 M, [Cl-]=7.496 M;[Fe tot]=1.131 M (63.13g/l), [H+]=6.697 M, [Cl-]=7.371 M.

Figure 2Extraction isotherms

of copper and zinc from feed solution:[Cu2+]=0.9592 M, [Zn2+]=0.3534 M,

[H+]=1.834 M, [Cl-]=7.243 M.

Extraction isotherms of metals from feed solution:[Fetot]=0.9643 M (53.85 g/l), [Zn2+]=0.3858 g/l,

[H+]=2.949 M, [Cl-]=4.043 M.

CONCLUSION

In the individual extraction of copper, zinc and iron, with the increase of the concentration of hydrochloric acid and chloride anions, Kelex 100 protonates in higher degree and extracts better the iron.

In the simultaneous extraction of copper and zinc, Kelex 100 extracted zinc better than copper. In the simultaneous extraction of zinc and iron, Kelex 100 extracted totally zinc, and iron remained in the

raffinate .ACKNOWLEDGEMENTS This study has been carried out with the financial support of both, the Grant scheme №BG051PO001-3.3.04/ 30 /28.08.2009under the Operational Program “Human Resources Development” 2007-2013, co-financed byEuropean Social Fund of European Community.

Table

[Zn2+], g/l

0.0 0.1 0.2 0.3

[Zn2

+ ], g

/l

0.0

0.1

0.2

0.3

0.4

Zn(II)

HORN HORN.HCl

Figure 3Extraction isotherm of zinc.

Extraction isotherm

of iron∆ [Fetot], g/l

I 4.628

II 0.5531

III 0.4102

IV

V

[Me2+], (M)

0.0 0.2 0.4 0.6 0.8 1.0

[Me(

II)]

, (M

)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

Zn(II)

Cu(II)

[H+], M

0.0 0.4 0.8 1.2 1.6 2.0 2.4____

[Me]

/[M

e] R

0.0

0.4

0.8

1.2

1.6

2.0

Fetot

Cu(II)

Zn(II)