RU2329098C1 - Method of extracting ions of heavy metals from water solutions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention pertains to methods of extracting ions of heavy metals through sorption on natural sorbents, containing cellulose and protein components, from solutions of complex mixtures. Proposal is given of a method of extracting ions of heavy metals from water solutions through contacting them, at room temperature, with modified polymer sorbents, which are by-products of treatment of oily raw material-extraction cakes or mill cakes. Solution/sorbent modulus is equal to 50-200.

EFFECT: increased degree of extraction and cheaper pre-processing of the sorbent.

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Description

FIELD OF TECHNOLOGY

The invention relates to methods for the extraction of heavy metal ions by sorption on natural sorbents containing cellulose and protein components from complex solutions in which natural complexones (lactic, citric, tartaric, oxalic acids, α-amino acids, etc.) or synthetic complexones ( Trilon B, etc.), including food systems of various compositions, and can be used to improve membrane and sorption technologies.

BACKGROUND

There is a method of wastewater treatment of industrial enterprises from heavy metals, in particular from copper ions, by sorption on sawdust treated with 4-methyl-8-oxo-5-azadskadiene-3,9-OH-2 with a sawdust-reagent mass ratio of 1 : 0.05 ÷ 0.1 [A.S. 1819669 USSR, MKI ⁵ V 01020/22. A method of producing a sorbent for wastewater treatment of copper // Timofeeva S.S., Kukharev B.F., Stankevich V.K., Klimenko G.R. - No. 4911863/05; Claim 05/15/91; Publ. June 7, 93, Bull. No. 21]. However, this method of modifying sawdust is uneconomical, since it implies the use of an expensive reagent in an amount of 5-10% by weight of the sorbent, and also leads to environmental pollution.

A known method for the separation of heavy metal ions on cellulose derivatives containing amino acid residues [Toshihiko Sato, Kazuhiro Karatsu, Hiromi Kitamura, Yasuo Ohno. Synthesis of cellulose derivatives containing amino acids residues and their adsorption of metal ions // Sanyi gakkaishi, Sen-i gakkaishi, J. Soc. Fiber Sci. and Technol., Jap. - 1983. V.39. N12. P.519-524]. As a result of the use of such cellulose polymers with grafted amino acid groups, the sorption capacity of cellulose-based sorbents increases from 4.7-17.3% for untreated microcrystalline cellulose to 17.9-99.8% on various samples of amino acid derivatives of cellulose upon sorption of various metals : Cu (II), Zn (II) and Cd (II). The best results were obtained in the case of extraction of copper, zinc and cadmium ions on lysine and cysteine cellulose from 0.2 mmol / l of chlorides of these metals.

However, the samples of amino acid derivatives of celluloses used in this method are scarce and expensive sorbents that were synthesized from cellulose isocyanate (obtained by heating for 4 hours a mixture of microcrystalline cellulose and 2,4-toluene-diisocyanate in dimethyl sulfoxide at 60 ° C in a nitrogen atmosphere) and amino acids at 30 ° C for 2 hours. In addition, the process of extraction of heavy metal ions from aqueous solutions using cellulose derivatives containing amino acid residues was carried out at a temperature of 30 ° C for 3 hours.

The closest in technical essence and the achieved result, that is, the prototype, is a method of extracting heavy metal ions from aqueous solutions by contacting them with polymer sorbents containing a cellulosic component and amino acid residues with a solution / sorbent module equal to 50-200 [T. Nikiforova E. ., Bagrovskaya N.A., Lilin S.A., Kozlov V.A. The method of extraction of heavy metal ions from aqueous solutions. RF patent №2258560. Publ. in BI No. 23 of 08/20/2005]. In this case, the secondary products of the processing of oilseeds - oilseed meal or cake, pre-treated in aqueous solutions of enzymes with a solution / sorbent module of 5-50 and enzyme concentration of 1-10% by weight of the sorbent for 1-3 hours at a temperature of 25 are used as a polymer sorbent -40 ° C, and the contacting of the treated sorbent is carried out for 5-20 minutes at room temperature.

As a result of the use of such sorbents, the degree of extraction of Cu (II), Zn (II), and Cd (II) ions for various individual and mixed samples of meal and meal was from 78.3 to 99.9%.

The disadvantages of the prototype are:

- low efficiency of the method (degree of extraction) when cleaning aqueous solutions of complex composition, which are multicomponent systems in which natural and synthetic complexones are present. The removal of heavy metal ions from such solutions is difficult, since the substances contained in them interact with metal cations to form strong complexes held in solution.

- the use of expensive and scarce reagents — enzymes and enzyme preparations — for pre-treatment of sorbents (100 mg of lipase obtained from Pseudomonada Cepacia costs 61.21 euros [Sigma. 2002-2003]); if lipase is produced by domestic industry, the enzyme preparation B ₁ mix is a prototype developed by genetic engineering at the Department of Enzymology of Moscow State University.

SUMMARY OF THE INVENTION

The objective of the invention is to provide a method for the extraction of heavy metal ions from aqueous solutions, allowing:

- clean solutions of complex composition, in which there are natural complexones (lactic, citric, tartaric, oxalic acids, α-amino acids, etc.) or synthetic complexones (Trilon B, etc.);

- increase the degree of extraction;

- reduce the cost of pre-treatment of the sorbent.

The problem is solved by creating a method for the extraction of heavy metal ions from aqueous solutions by contacting them at room temperature with modified polymer sorbents, which are secondary products of the processing of oilseeds - meal or cake, with a solution / sorbent module equal to 50-200, while the modification sorbents are carried out by processing them in an aqueous solution containing the sodium salt of monochloracetic acid in an amount of 1-10% by weight of the sorbent and soda or alkali to create a pH of 8-12, p module and solution / sorbent 5-50 for 30-60 minutes in a boiling water bath and then an acid is added to pH 4-7, and contacting the modified sorbent is carried out for 0.5-1.5 hours.

Meal and cake are formed as production waste after oil is extracted from oilseeds by pressing or extraction, respectively, and contain a mixture of cellulosic (up to 14%) and protein (up to 45%) biopolymers, as well as up to 4% fat. Were used: rapeseed meal [GOST 30257-95. Meal rapeseed tested. Specifications], soybean meal [GOST 12220-96. Soybean meal fodder tested. Specifications], sunflower meal [GOST 80-96. Sunflower cake. Specifications], linen cake [GOST 10974-95. Linen cake. Specifications].

Sodium salt of monochloracetic acid ClCH ₂ COONa qualification "reagent grade" is a white powder; highly soluble in water; molecular weight 116.48; melting point 199 ° C [TU 6-01-32-93]; the cost of 31.5 rubles per 1 kg (CJSC Polymer, Yekaterinburg).

To create a pH of 8-12, alkali (NaOH or KOH) or soda (Na ₂ CO ₃ or NaHCO ₃ ) was added during the treatment of the sorbents with the sodium salt of monochloracetic acid. NaOH [GOST 2263-79. Technical caustic soda. Specifications]. NaOH is a white granule, readily soluble in water; molecular weight 40.00. KOH [GOST 24363-80. Potassium hydroxide. Specifications]. KOH is a white flake that is highly soluble in water; molecular weight 56.11. Na ₂ CO ₃ [GOST 83-79. Sodium carbonate. Specifications]. Na ₂ CO ₃ is a white granular powder, readily soluble in water; molecular weight 105.99. NaHCO ₃ [GOST 4201-79. Sodium carbonate. Specifications]. NaHCO ₃ is a white crystalline powder soluble in water; molecular weight 84.01.

To create a pH of 4-7, after treatment of the sorbents with the sodium salt of monochloracetic acid, a strong mineral acid, for example, HCl, was added [GOST 3118-77. Hydrochloric acid. Specifications] or H ₂ SO ₄ [GOST 4204-77. Sulfuric acid. Specifications]. Hydrochloric acid is an aqueous solution of hydrogen chloride - a colorless liquid with a pungent odor, smoking in air; mixes up with water; density 1.17-1.19 g / cm ³ ; molecular weight 36.46. Sulfuric acid is a colorless, transparent, oily liquid, odorless; mixes up with water; density 1.83 g / cm ³ ; molecular weight 98.08.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

Example 1

10 g of rapeseed meal is poured into 500 ml of an aqueous solution (module 50) containing 1 g (10% by weight of the meal) of monochloracetic acid sodium salt and 0.5 g of soda, at pH 8 and incubated for 30 minutes in a boiling water bath (at a temperature of 100 ° C), after which the solution is cooled to room temperature, a dilute solution of hydrochloric acid is added and the pH of solution 4 is adjusted, then the solution is filtered off, and the sorbent is washed with distilled water and dried.

The treated sorbent is poured into 0.5 L of an aqueous solution at room temperature (module 50) containing 0.15 mmol / L of copper ions and 10 g / L of lactic acid. After 30 minutes, the solution is filtered off and the content of Cu (II) ions is determined in the filtrate. The concentration of copper ions after three sorption cycles was 0.0003 mmol / L (99.8% recovery).

Example 2

10 g of sunflower meal is poured into 300 ml of an aqueous solution (module 30) containing 0.5 g (5% by weight of meal) of sodium salt of monochloracetic acid and 0.35 g of soda, at pH 9 and incubated for 40 min in a boiling water bath (at temperature 100 ° C), after which the solution is cooled to room temperature, a dilute solution of sulfuric acid is added and the solution is adjusted to pH 5, then the solution is filtered off and the sorbent is washed with distilled water and dried.

The treated meal is poured into 1 l of an aqueous solution at room temperature (module 100) containing 0.15 mmol / l of zinc ions and 10 g / l of tartaric acid. After 45 minutes, the solution was filtered and the content of Zn (II) ions was determined in the filtrate. The concentration of zinc ions after three cycles of sorption was 0,00075 mmol / L (the degree of extraction of 99.9%).

Example 3

10 g of flaxseed cake is poured into 50 ml of an aqueous solution (module 5) containing 0.1 g (1% by weight of meal) of monochloracetic acid sodium salt and 0.08 g of alkali at pH 10 and incubated for 45 minutes in a boiling water bath (at temperature 100 ° C), after which the solution is cooled to room temperature, a dilute hydrochloric acid solution is added and the solution is adjusted to pH 6, then the solution is filtered off and the sorbent is washed with distilled water and dried.

The treated meal is poured into 750 ml of an aqueous solution at room temperature (module 75) containing 0.15 mmol / L of cadmium ions and 10 g / L of oxalic acid. After 60 minutes, the solution was filtered and the content of Cd (II) ions was determined in the filtrate. The concentration of cadmium ions after three sorption cycles was 0.0003 mmol / L (99.8% recovery).

Example 4

10 g of a mixture of soybean and rapeseed meal is poured into 100 ml of an aqueous solution (module 10) containing 0.7 g (7% by weight of the meal) of monochloracetic acid sodium salt and 0.25 g of soda, at pH 12 and incubated for 1 hour in boiling water bath (at a temperature of 100 ° C), after which the solution is cooled to room temperature, a dilute solution of sulfuric acid is added and the pH of solution 7 is adjusted, then the solution is filtered off, and the sorbent is washed with distilled water and dried.

The treated sorbent mixture is poured into 2 L of an aqueous solution at room temperature (module 200) containing 0.15 mmol / L of copper, zinc and cadmium ions. After 90 minutes, the solution is filtered off and the content of Cu (II), Zn (II) and Cd (II) ions is determined in the filtrate. The concentration of copper, zinc and cadmium ions after three sorption cycles was 0.0009, respectively; 0.015 and 0.032 mmol / L (the degree of extraction of Cu (II), Zn (II) and Cd (II) ions is 99.4; 90.0 and 78.6%).

To evaluate the effectiveness of the prototype method, experiments were carried out to extract heavy metal ions from solutions in which complexons are present, using meal and meal treated with enzymes.

The results of the experiments are presented in the table.

Thus, from the above examples and table data, it follows that the proposed method allows us to solve the problem, namely, to clear solutions of complex composition in which natural or synthetic complexones are present (lactic, citric, tartaric, oxalic acids, etc.); at the same time, to achieve high degrees of purification (the degree of extraction of metal ions from solutions of complex composition with sorbents modified by the proposed method is higher than for sorbents modified according to the prototype), and also reduce the cost of processing the sorbent: instead of expensive enzyme preparations, use sodium salt of monochloracetic acid.

Claims (1)

The method of extraction of heavy metal ions from aqueous solutions by contacting them at room temperature with modified polymer sorbents, which are secondary products of the processing of oilseeds - meal or cake, with a solution / sorbent module equal to 50-200, characterized in that the sorbents are modified by processing them in an aqueous solution containing the sodium salt of monochloracetic acid in an amount of 1-10% by weight of the sorbent and soda or alkali to create a pH of 8-12, with a solution / sorbent module of 5-50 in t 30-60 minutes in a boiling water bath, after which a dilute solution of a strong mineral acid is added to a pH of 4-7, and the contacting of the modified sorbent is carried out for 0.5-1.5 hours.