SEPARATION OF IRON IONS FROM TECHNOLOGICAL SOLUTIONS BY LIQUID EXTRACTION METHOD

ABSTRACT

The mixture of toluene and trialkylamine is the right choice of iron ions as an extractant for the technological solution of non-ferrous metals. This is because after extraction it is possible to observe a sharp decrease in the concentration of iron ions in the aqueous phase.

Keywords: separation, extraction, iron ions.

Liquid extraction is the process of transition of one or more solutes from one liquid phase to another. The second phase (extractant) is completely insoluble or partially soluble in the first phase, but it dissolves substances absorbed from the first phase. The initial aqueous solution containing the dispersant is in direct contact with the extractant. As a result, two phases are formed:

1) Extragent - a separate organic phase enriched with a dispersing substance.

2) Raffinate - an aqueous phase in which there is no dispersing substance.

The main stages of liquid extraction:

1) contact of media and phase dispersion;

2) separation of phases into layers (extract phase) and raffinate (depletion phase);

3) extraction of target components from the extract and regeneration of the extractant by distillation or re-extraction (reverse process to liquid extraction);

4) washing the extract to reduce the amount of mechanically removed starting solution [1].

When the extracted extract is treated with certain aqueous solutions, the target components are converted into a solution or precipitate. This process is called the re-extraction process.

The phase separation of the emulsion formed during extraction is usually performed in two stages. First, large droplets precipitate rapidly (float) and large droplets coalesce. Very small droplets remain in the form of "fog", which settles very slowly. Various devices are used to speed up this process.

The mechanism of the extraction process is shown in Figure 1. From this picture you can see the mechanism of extraction: after mixing the extractant with the initial solution, you can separate the extract and raffinate containing the solute [1].

Figure 1. The mechanism of the extraction process

The extraction process is important for many industries, as it allows you to purify many impurities and extract pure substances. Areas of application:

- chemical;

- oil refining;

- food;

- metallurgy;

- pharmaceutical.

This method can be used in the metallurgical industry in the production of non-ferrous metals in the purification of process solutions from iron ions.

For some enterprises producing non-ferrous metals, the presence of iron ions in process solutions adversely affects the process and makes it difficult to obtain a pure product. The use of liquid extraction in the purification of solutions from iron ions significantly simplifies the separation of iron ions from non-ferrous metal ions [2].

The proposed method has a number of advantages:

- this method can be used for solutions with an acidity of 10 to 70 grams per liter;

- significantly simplifies the work of production with the right choice of equipment;

- long service life of the extractant;

- the ability to purify the extractant from iron ions using the method of re-extraction;

- the extracted iron is easy to process.

Research plan.

1) Selection of an extractant (solvent and reagent) suitable for the separation of iron ions from the process solution.

2) Determine the ratio of organic and aqueous liquid phase required for the analysis.

3) Determination of the maximum solubility of iron ions in the selected extractant.

4) Selection of a re-extraction solution suitable for purification of the extractant from iron ions [3].

Perform research.

The following organic solvents were used as extractants:

- diesel fuel;

- chloroform;

- isobutyl alcohol;

- toluol.

The following substances were used as reagents:

- Cyanex – 272;

- tributylphosphate (TBP);

- trialkylamine (TAA);

- Aliquat.

After a number of studies, toluene was selected as a solvent for the extraction of iron ions, and trialkylamine was selected as the reagent. The ratio of organic and aqueous phases was 2/1. The maximum solubility of iron ions in the obtained compound was 6 g/dm³ [2].

Sulfuric acid with a concentration of 120 g/dm³ was selected as a re-extraction agent.

After performing all the experiments to determine the extractant, to determine the ratio of the organic phase to the aqueous phase, to determine the maximum solubility and the extractable solution, the first experiment was performed with the process solution.

The test was performed in a 200 ml volumetric flask with a ratio of the organic phase to the aqueous phase ½. Mixing was performed manually for 15 minutes [3].

Upon completion of the mixing, the separation of the two phases took place immediately. The results are presented in Table 1.

Table 1.

Research results

Summing up the experiment, it can be seen that the mixture of toluene and trialkylamine is the right choice of iron ions as an extractant for the technological solution of non-ferrous metals. This is because after extraction it is possible to observe a sharp decrease in the concentration of iron ions in the aqueous phase (the concentration of iron ions in the initial solution is 2352 mg/dm³, and the final concentration of iron in the extract is 54 mg/dm³) and the degree of purification was 97.7% [2].

Re-extraction (purification) of the extractant from iron ions with sulfuric acid was successful. The concentration of iron ions in the reconstituted solution was 2184 mg/dm³ and the losses were low (7%).

The results showed that this extractant (toluene and trialkylamine) can be used in the future for the separation of iron ions. The experiment was repeated 22 times with this extractant, the results were completely consistent.

Reference:

1. Gindin L. M. Extraction processes and their application. - M.: Nauka, 1984. - 281 p.
2. Zolotov Yu. A. Extraction in inorganic analysis. - M.: Publishing House of Moscow State University, 1988. - 82 p.
3. Zyulkovsky Z. Liquid extraction in the chemical industry. - L.: Goshimizdat, 2019. - 480 p.