APPLICATION OF ANION EXCHANGE FOR THE SEPARATION AND CONCENTRATION OF TRACE TITANIUM

R. D. Glukhovskaya, Yu. L. Lel’chuk, E. D. Luker

(Presented by the scientific seminar of the Department of Analytical Chemistry)

The study of the sorption and desorption of anionic chloride complexes of a number of metals on the anion exchangers AN-2F and Tseralit FF enabled us to develop highly sensitive methods for determining trace iron [1–3] and trace copper and iron from a single sample [4] in certain materials used in the production of phosphor L-34.

In the present communication, results are given from a study of the sorption and desorption of titanium chloride complexes on the same anion exchangers. The purpose of the work is to determine the conditions for separating and concentrating traces of this element and to develop a method for the simultaneous determination of trace iron, copper, and titanium from a single sample in the same materials.

Experimental Part

Hydrochloric acid was almost completely purified of traces of copper, iron, and titanium by isothermal distillation followed by chromatographic purification on columns with AN-2F and Tseralit FF.

The initial standard titanium solution with a titer of 100 μg/ml was prepared from titanium dioxide by fusion with potassium pyrosulfate. The titer of the solution was checked by the gravimetric method [5].

Working standard solutions with titers of 1 and 5 μg/ml were prepared by diluting the initial solution with hydrochloric acid of the appropriate concentration.

Titanium in the solutions studied was determined photometrically in the form of a colored complex with diantipyrylmethane [6]. The latter was synthesized by condensation of antipyrine with formaldehyde in a hydrochloric-acid medium [7].

The calibration curve was constructed in the range from 1 to 10 μg at pH 4–5. Into 25-ml volumetric flasks were placed 1 to 10 μg of the standard titanium solution, 1 ml of a 7% ascorbic acid solution, 2 drops of a 5% copper sulfate solution, and 5 ml of a 5% diantipyrylmethane solution, and the volume of the solution was brought to the mark with 5 N hydrochloric acid. The contents of the flasks were mixed and, after 30–40 min, the optical density of the solutions was measured in cuvettes with a layer thickness of 5 cm using a blue light filter with a transmission maximum at 413 mμ. Water served as the comparison solution. The optical-density readings of the blank were subtracted from the sample readings.

Preparation of the columns for operation was described by us earlier [1–4]. In the actual

It was first established that titanium from solutions of a titanium salt in 0.1 N hydrochloric acid is not sorbed by anion exchangers. Acid of this concentration was subsequently used by us for eluting titanium from anion-exchange columns.

The study of titanium sorption in hydrochloric acid solutions of various concentrations was carried out as follows: 10 ml of hydrochloric acid of a given normality, with a specified addition of titanium, was passed through columns packed with AN-2F or ceralite FF with a bed height of 22 cm, at a rate of 2–3 ml per minute. Charging the anion exchanger into the Cl form and washing the sorbed complex were carried out with hydrochloric acid of the same concentration. Titanium was eluted with 0.1 N hydrochloric acid, in separate portions of which the titanium was determined with diantipyrylmethane [6]. The experiments performed showed that the chloride complex of titanium is not sorbed by ceralite FF and is completely washed out with 40–60 ml of hydrochloric acid at concentrations from 0.1 to 10 N. Similar results were obtained on AN-2F at HCl concentrations from 0.1 to 6 N. However, when more concentrated HCl solutions are used, the behavior of the chloride complex of titanium with respect to AN-2F changes sharply. From the sorption curve (Fig. 1) it is evident that in 7 N hydrochloric acid solutions partial sorption is observed, while at 8–10 N concentration the anion exchanger firmly retains the complex, which is not removed when a further 100 ml of hydrochloric acid of the same concentration is passed through.

Fig. 1. Sorption curve of the chloride complex of titanium.

The curve in Fig. 2 characterizes the dynamics of elution of the sorbed

Fig. 2. Elution curve of the chloride complex of titanium.

of the chlorinated titanium chloride complex from the anion-exchange column with AN-2F. For complete elution of titanium, 15–20 ml of 0.1 N hydrochloric acid is sufficient.

We also determined the exchange capacities of anion exchangers for titanium under static conditions by the procedure described earlier [4] and calculated the distribution coefficients \((\varphi)\). The data obtained are given in the table.

Table

Results of studying the exchange capacity of anion exchangers for titanium under static conditions
(Solution volume 50 ml. Amount of anion exchanger 0.25 g. Titanium added 4.658 mg)

Conclusions

The processes of sorption and desorption of titanium on the anion exchangers ceralite FF and AN-2F were studied. It was established that, under dynamic conditions, titanium is not sorbed by ceralite FF from 0.1–10 N HCl solutions, but it is quantitatively sorbed by the anion exchanger AN-2F at an HCl concentration of 8–10 N. For elution of the sorbed titanium, 15–20 ml of 0.1 N HCl is sufficient.

The data obtained were used to develop a sorption-photometric method for the determination of traces of titanium in certain materials.

References

1. R. D. Glukhovskaya, Yu. L. Lel’chuk, Proceedings of the Scientific and Technical Conference of the Tomsk Branch of the Mendeleev All-Union Chemical Society, 54, 1968.

2. R. D. Glukhovskaya, Yu. L. Lel’chuk. Abstracts of reports of the meeting on analytical chemistry of semiconductor substances, 19, 46, Kishinev, 1965.

3. R. D. Glukhovskaya, Yu. L. Lel’chuk, E. D. Lukker. Izv. TPI, vol. 152, 52, 68 (1969).

4. Yu. L. Lel’chuk, R. D. Glukhovskaya, E. D. Lukker, G. N. Dembovskaya. Izv. TPI, vol. 174, 68 (1968).

5. Yu. N. Knipovich, Yu. V. Morachevskii. Analysis of Mineral Raw Materials. Goskhimizdat, Leningrad, 755, 1956.

6. L. L. Skripova, G. A. Chervenchuk, A. N. Pokrovskaya. Izv. TPI, vol. 174, 1968.

7. V. P. Zhivopistsev. Factory Laboratory, No. 10, 1186 (1960).