RU2491977C1 - Extraction of iron ions from water solutions with vegetable oils - Google Patents

Abstract

FIELD: medicine, pharmaceutics.

SUBSTANCE: invention can be applied in chemical industry, metallurgy and purification of industrial and domestic sewages. Extraction of iron with vegetable oils is realised from water solution with ratio water (W) to organic (O) phase W:O≥3 for Fe (III) and W:O= 3-6 for Fe(II); at pH 2-3 for Fe (III) and 9-11 for Fe (II) and Fe (III). Time of extraction for Fe (III) is 1-3 min and not more than 60 min for Fe (II).

EFFECT: method ensures high degree of efficiency of iron extraction from water solutions with simultaneous efficiency and safety of the process.

2 cl, 10 dwg, 3 tbl

Description

The method of extraction of iron from aqueous solutions relates to the field of extraction of substances with organic extractants from aqueous solutions and can be used in non-ferrous and ferrous metallurgy, as well as for the treatment of industrial and domestic wastes.

A known method of producing iron by reducing iron ores to metal [Ripan R., Chetyanu I. Inorganic chemistry, part 2. - M .: Mir, 1972, p. 485].

The disadvantage of this method is the high energy consumption and the formation of environmentally hazardous emissions into the atmosphere.

The closest technical solution is the method of extraction of iron ions from hydrochloric acid aqueous solutions with tributyl phosphate (TBP) in the processing of natural and industrial raw materials [I.D. Reznik, G.P. Ermakov, Y.M. Schneerson. Nickel, part 3. - M.: Science and Technology LLC, 2004. 608 p. Materials of the VII International Conference "Sustainable Development of Mountain Territories in the Context of Global Changes", Vladikavkaz. 2010. S. 45].

The disadvantage of this method is the contamination of the final products with phosphorus due to the solubility of TBP in hydrochloric acid solutions. In addition, the extractant undergoes hydrolysis, destruction and destruction with deterioration of extraction properties.

The objective of the invention is the use of an economical and efficient method for the extraction of iron from aqueous solutions.

The technical result that can be obtained using the invention is the cost-effectiveness and efficiency of the extraction of iron from aqueous solutions.

This technical result is achieved by the fact that in the known method of extracting iron from an aqueous solution, including contacting the extractant and the solution, mixing the mixture, settling and separating the phases, the extraction is carried out from the aqueous solution with vegetable oils in the ratio of aqueous (B) to organic (O) phase B : O≥3 for Fe (III) and B: O = 3-6 for Fe (II) at pH 2-3 for Fe (III) and 9-11 for Fe (III) and Fe (II) and extraction time 1 -3 min for Fe (III) and not more than 60 min for Fe (II).

The essence of the method is illustrated by the data of figures 1-10, which indicate the concentration of iron in the initial solutions, the extraction time at a given pH value, the iron concentration and pH in the clarified aqueous phase, the distribution coefficient D, calculated as the ratio of the equilibrium concentrations of iron in organic and aqueous phases, extraction ε,% of the mass. from the original, the separation coefficient β = D _{Fe (III)} / D _{Fe (II)} .

Stirring and maintaining the desired pH value was carried out until, in the future, the acid-base characteristics of the system changed slightly. However, for a greater guarantee of achieving equilibrium, the contact of the organic and aqueous phases was carried out for at least a day. Upon reaching equilibrium between the organic (O) and clarified aqueous phases (B), the organic phase was separated from the aqueous phase; in the latter, the pH value and residual iron concentration were determined. To maintain a given pH value of the solution during the extraction, solutions of alkali NaOH and acid H ₂ SO _{4 were} used as neutralizers.

Using the values of the concentrations of iron in the aqueous solution, the initial one and after extraction, the distribution coefficient of iron D between the organic and aqueous phases was calculated.

For the study, crystalline hydrates of FeCl ₃ · 6H ₂ O and FeSO ₄ · 2H ₂ O salts were used.

Practical examples

Example 1 (FIG. 1)

Figure 1 shows the dependence of the residual concentration of Fe (III) ions on the pH of the solution. C ₀ = 1.26 g / dm ³ ; O: B = 1: 3, time - day. Extraction is carried out at pH = 2-3 and 9-11. At pH≤1, the iron ion is not extracted, and at pH> 11, black precipitates form. In the range of pH = 4-8, brown precipitates are formed. It can be assumed that, near the pH of the hydrate formation of Fe (III), extraction is carried out due to the ionic bond between the oleic acid anion and the Fe (III) cation, and in the pH range 9–11, a Fe (III) complex with extractant components and OH ions ^{is formed} solvating into the organic phase. The best results were obtained at pH 10, during the day of extraction, the residual concentration is C = 0.1025 g / dm ³ , D = 33.88. The structure of the oil phase is gel-like, the color is brown. Under the same conditions, Fe (II) is extracted only at pH 10, from a solution of C ₀ = 1.28 g / dm ³ within 1 hour of extraction, the residual concentration of Fe (II) is C = 0.094 g / dm ³ ; D = 34.46. In the range of pH = 4-9, brown precipitates are formed. It is likely that the extraction of Fe (II) is associated with the oxidation of the Fe (II) ion to Fe (III) and the extraction of the latter with an oil phase. This is also evidenced by close values of the distribution coefficients D of both the Fe (II) ion and the Fe (III) ion.

Example 2 (figure 2, 3)

Figure 2 shows the dependence of the distribution coefficient D on the ratio of the aqueous phase (B) to the organic (O) B: O from solutions of Fe (III) salts at pH 10. The extraction of Fe (III) ions is carried out at B: O≥3 almost immediately , the residual concentration is approximately the same and equal to C = 0.095 g / dm ³ . During the extraction of Fe (III) ions, a brown coating is formed at the bottom of the glass.

Figure 3 shows the dependence of the distribution coefficient D of Fe (II) ions on the B: O ratio. The extraction of Fe (II) ions is carried out in the range B: O = 3-6. For the ratio B: O = 3 and 4, C ₀ = 1, 56 and 1.71 g / dm ^3, respectively, and for B: O = 5 and 6 C ₀ = 1, 16, and 1.28 g / dm ^3, respectively. At B: O≥7, black precipitates form. In the process of extraction, the Fe (II) ions are oxidized to Fe (III), therefore, curve 1 was obtained based on the total iron, and curve 2 was obtained on Fe (II).

Example 3 (Figs. 4-6, Table 1)

Figure 4 shows the dependence of the distribution coefficient D on the initial concentration of Fe (III) and Fe (II) ions, g / dm ³ from their individual solutions. Extraction conditions: pH 10, O: B = 1: 3. The extraction of Fe (III) ions occurs almost immediately, the residual concentration is approximately the same and equal to C = 0.095 g / dm ³ . At C ₀ > 3 g / dm ³ , brown precipitates form. The extraction of Fe (II) ions is carried out within 1 hour. At C ₀ > 1.6 g / dm ³ , black precipitates form. The dependences D = f (C ₀ ) are linear:

Fe (III) D = 31.62 C ₀ -3.533 (R ² = 0.997) F (ii) D = 11.18 C ₀ +16.75 (R ² = 0.919)

Figure 5 shows the dependence of the residual concentration of Fe (II) ions on the extraction time. Extraction conditions: pH 10, O: B = 1: 3, t = 22 ° C. The process ends in 30 minutes at O: B = 1: 3 and 70 minutes at O: B = 1: 4.5.

Figure 6 shows the isotherm of extraction of Fe (II) ions — the dependence of the distribution coefficient D on the equilibrium concentration of Fe (II) ions, g / dm ³ . Extraction conditions: pH 10, O: B = 1: 3, t = 22 ° C.

The data in Table 1 characterize the dependences С = f (τ), ln (С ₀ / С) = f (τ), 1 / С = f (τ), 1 / С ² = f (τ). It can be seen that with the ratio O: B = 1: 4.5 and t = 22 ° C, the process is described by the kinetic equation of zero order, it is likely that it does not depend on the concentration, but is determined by the area of the interface.

Table 1 The correlation coefficient for the dependencies C: = f (τ), ln (C ₀ / C) = f (τ), 1 / C = f (τ), 1 / C ² = f (τ), obtained according to Fig.5 t / c B: o S, g / dm ³ R ² C = (τ) ln (C ₀ / C) = f (τ) 1 / C = f (τ) 1 / C ² = f (τ) 22 3: 1 1,59 0.723 0.964 0.958 0.835 22 3: 1 0.99 0.646 0.948 0.943 0.833 22 3: 1 0.51 0.684 0,991 0.870 0.790 22 4,5: 1 1.42 0.975 0.948 0.751 0.602

From the data of table 1 it follows that with the ratio O: B = 1: 3 functions

ln (С ₀ / С) = f (τ) are linear and have the form

ln (С ₀ / С) = Кτ, (1)

where K is the rate constant of the process.

According to figure 5, the calculated values of K in equation (1):

C ₀ , g / dm ³ 0.51 0.99 1,59 K, min ^-1 0,064 0,050 0,041

In the range of initial concentrations With ₀ = 0.51-1.59 g / DM ³ with increasing concentration, the process speed decreases.

Example 4 (Fig.7-9, table 2)

Figure 7 shows the temperature dependence of the residual concentration of Fe (II) ions.

The data in Table 2 characterize the dependences C = f (τ), ln (C ₀ / C) = f (τ), 1 / C = f (τ), I / C ² = f (τ) according to Fig.7.

From the data in Table 2 it follows that for the ratio O: B = 1: 3 and t = 15-35 ° С, the functions ln (С ₀ / С) = f (τ) are linear and are described by equation (1).

According to Fig.7 calculated values of K in equation (1):

t, ° C fifteen 22 35 K, min ^-1 0,023 0,050 0,093

In the temperature range t = 15-35 ° C with an increase in temperature, the process speed increases.

table 2 The correlation coefficient for the dependences C = f (τ), ln (C ₀ / C) = f (τ), 1 / C = f (τ), 1 / C ² = f (τ) obtained according to Fig.7 t, ° C IN S, g / dm ³ R ² C = (τ) ln (C ₀ / C) = f (τ) 1 / C = f (τ) l / C ² = f (τ) fifteen 3: 1 1,50 0.962 0.964 0.872 0.802 22 3: 1 1,59 0.723 0.964 0.958 0.835 35 3: 1 1,50 0.828 0.970 0.965 0.850

On Fig given the dependence of the distribution coefficient D on temperature, ° C, from individual solutions of salts of Fe (III) and Fe (II). Extraction conditions: pH 10, O: B = 1: 3, Co, g / dm ³ : 2 Fe (III), 1 Fe (II). Extraction from solutions of Fe (III) salts occurs almost instantly, and from solutions of Fe (II) salts within an hour.

In Fig. 9, according to Fig. 7, the dependence of the logarithm of the residual concentration of Fe (II) ions on the inverse temperature is T = 288, 295, 308 ° K (t = 15, 22, 35 ° C). The extractant is olive oil, C ₀ = 1.5 g / dm ³ , pH 10, O: B = 1: 3.

According to Fig.9 for the Arrhenius equation of the form

lnk = lnk ₀ -E / RT,

where ln k ₀ is the pre-exponent,

E is the activation energy of the extraction process, J / mol,

R = 8.314 J / (mol · degree) - universal gas constant,

the value of activation energy equal to E = 52378 J / mol was calculated.

Based on the kinetic analysis of the reaction, it can be assumed that the first order of the process and the average activation energy E = 52.4 kJ / mol indicate that, probably, the extraction of iron (II) ions with vegetable oil lies in the kinetic region and is limited by oxidation Fe (II) to Fe (III) and the subsequent formation of a complex of Fe (III) ions with components of the extractant, which is solvated into the organic phase.

Example 5 (figure 10).

Figure 10 shows the dependence of the distribution coefficient D on the type of vegetable oil: 1 - apricot, 2 - pumpkin, 3 - cedar, 4 - soybean, 5 - grape, 6 - corn, 7 - walnut, 8 - sunflower, 9 - linseed 10 - olive.

Extraction conditions: O: B = 1: 3, pH 10, t = 20 ° С, С ₀ = 1.4-1.5 g / dm ³ .

All studied oils extract well Fe (III) ions.

High rates of extraction of Fe (II) ions were obtained for apricot, soybean, sunflower and linseed oil and poorly extract Fe (II) ions from olive, pumpkin, cedar and corn.

Example 6 (table 3)

Table 3 shows the results of the extraction of iron ions from a mixture of Fe (II) and Fe (III) salts. Extraction conditions: pH 10; O: B = 1: 4.5; t = 20 ° С, extraction time 1-3 min, initial concentration С ₀ and final concentration С, g / dm. The distribution coefficient D, the separation coefficient β = D _{Fe (III)} / D _{Fe (II)} , extraction ε, in% of the initial value are obtained. It is seen that with increasing concentration, the separation coefficient increases.

Table 3 The results of the extraction of iron ions from a mixture of salts of Fe (II) and Fe (III) C ₀ , g / dm ³ S, g / dm ³ D ε,% β Fe (II) Fe (III) Fe (II) Fe (III) Fe (II) Fe (III) Fe (II) Fe (III) 0.54 0.54 0.10 0.10 19.8 19.8 81.48 81.48 1.00 0.92 0.92 0.11 0.10 33.14 36.90 88.04 89.13 1,11 1.99 2.05 0.85 0.18 6.03 46.75 57.29 91.22 7.75

In the process of extraction, the extract has a gel structure, its volume increases by 5-10% of the volume of the extractant.

Precipitation of Fe (III) hydroxocomplexes is brown, and Fe (II) precipitation is black. The black precipitates after drying are magnetic and have the composition FeO · Fe ₂ O ₃ or Fe ₃ O ₄ .

High extraction rates were obtained, probably because vegetable oils contain oleic acid and other components that can extract heavy metal ions. Vegetable oils are saturated and unsaturated (with one, two and three double bonds) monobasic fatty acids with an unbranched carbon chain and an even number of carbon atoms (mainly C ₁₆ and C ₁₈ ). So, the content of oleic acid,% wt .: in sunflower oil 24-40, in corn oil - 30-49, in olive oil - about 80, in soybean oil - 23-29. In addition, fatty acids with an odd number of carbon atoms (from C ₁₅ to C ₂₃ ) were found in vegetable oils in small amounts.

High rates of extraction of non-ferrous metal ions by vegetable oils also indicate that in the zone of influence of industrial enterprises non-ferrous metal ions can accumulate in plants from the soil, especially when discharging untreated industrial wastewater. This indicates a high environmental hazard to plants and animal non-ferrous metal ions that enter the soil as a result of industrial enterprises.

Claims (1)

A method of extracting iron ions from an aqueous solution, including contacting the extractant and the solution, mixing the mixture, settling and separation of the phases, characterized in that the extraction is carried out from the aqueous solution with vegetable oils at a ratio of aqueous (B) to organic (O) phase B: O≥3 for Fe (III) and B: O = 3-6 for Fe (II); at pH 2-3 for Fe (III) and 9-11 for Fe (II) and Fe (III) and an extraction time of 1-3 minutes for Fe (III) and not more than 60 minutes for Fe (II).

Images