RU2438995C1 - Method of extracting ions of heavy metals from aqueous solutions - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention can be used in water treatment, in techniques for recycling ions of heavy metals from aqueous solutions and waste water. The method of extracting ions of heavy metals from aqueous solutions involves contact of these solutions at room temperature with cellulose-based modified polymer sorbents with solution/sorbent modulus equal to 50-200. The sorbents are modified through their reaction with an oxidising agent with exposure to microwaves with power 300 W and frequency 2.45 GHz, at temperature 25-70C for 5-15 minutes, followed by washing with water and treatment with sodium bisulphite. Contact between the modified sorbent and the purified solutions is 1-20 minutes long. The sorbents are treated in an oxidising agent solution with concentration of 0.1-0.3 M at pH 2.5-4.5, and treatment with sodium bisulphite is carried out in a solution with concentration 0.5-5% at pH 2-4.5 for 0.5-1 hour. The oxidising agent used is sodium metaperiodate, periodic acid or sodium hypochlorite, and the sorbents used are cotton or wood cellulose, short flax fibre or wood shavings. ^ EFFECT: invention enables to increase the degree of extraction of ions of heavy metals from solutions with metal ion concentration of 1,5 mol/l by 13-15% and cut sorption time to 1-20 minutes. ^ 3 cl, 1 tbl, 5 ex

Description

FIELD OF TECHNOLOGY

The invention relates to methods for the extraction of heavy metal ions by sorption on natural cellulose-containing sorbents, from solutions of various compositions resulting from a variety of technological processes, and can be used to improve membrane and sorption technologies, in water treatment, in the development of technologies for the disposal of heavy metal ions from water solutions and wastewater of various nature.

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-azadecadiene-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 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 of 50-200. As a sorbent use meal or cake, pre-treated in aqueous enzyme solutions with a solution / sorbent module of 5-50 and an enzyme concentration of 1-10% by weight of the sorbent for 1-3 hours at a temperature of 25-40 ° C, and contacting the treated sorbent 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 cake was from 78.3 to 99.9% [T. Nikiforova, 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].

However, this method involves 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.

The closest in technical essence and the achieved result, that is, the prototype, is a method for extracting heavy metal ions from aqueous solutions by contacting them at room temperature with modified polymer sorbents, with a solution / sorbent module equal to 50-200. In this case, the secondary products of the processing of oilseeds - oilseed meal or meal, pretreated in an aqueous solution containing 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, are used as a polymer sorbent with a module solution / sorbent 5-50 for 30-60 minutes in a boiling water bath, after which a dilute solution of a strong mineral acid (Hcl or H ₂ SO ₄ ) is added to a pH of 4-7, and the contacting of the modified sorbent is carried out for 0.5- 1.5 hours [Nikiforova T.E., Kozlov V.A., Rodionova M.V. The method of extraction of heavy metal ions from aqueous solutions. RF patent No. 2329098. Publ. in BI No. 20 of July 20, 2008].

The disadvantages of the prototype are:

- insufficiently high degree of extraction of heavy metal ions from more concentrated solutions (with a concentration of metal ions of 1.5 mmol / l);

- long sorption time (0.5-1.5 hours).

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:

- increase the degree of extraction of heavy metal ions from more concentrated solutions (with a concentration of metal ions of 1.5 mmol / l);

- reduce sorption time.

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 cellulose-based polymer sorbents with a solution / sorbent module of 50-200, in which the sorbents are modified by their interaction with an oxidizing agent under microwave irradiation 300 W with a frequency of 2.45 GHz and a temperature of 25-70 ° C for 5-15 minutes, followed by washing with water and treatment with sodium bisulfite, while modifying contact -skilled sorbent is carried out for 1-20 min.

The interaction of sorbents with an oxidizing agent is carried out in a solution with a concentration of 0.1-0.3 M at a pH of 2.5-4.5, and treatment with sodium bisulfite is carried out in a solution with a concentration of 0.5-5% at a pH of 2-4.5 V for 0.5-1 hours at room temperature

At the same time, sodium metaperiodate, iodic acid or sodium hypochlorite are used as an oxidizing agent, and cotton or wood pulp, short flax fiber or sawdust are used as polymer sorbents.

As reagents used:

- iodic acid - HIO ₄ [TU 6-09-02-87-74];

- sodium metaperiodate - NaIO ₄ [TU 6-09-02-54-74];

- sodium hypochlorite - NaOCl [GOST 11086-76. Sodium hypochlorite. Specifications.];

- sodium bisulfite - NaHSO ₃ [GOST 902-76. Technical sodium bisulfite (aqueous solution). Specifications.];

As sorbents used:

- short flax fiber, which is a secondary product of processing the flax industry of the following composition,%: cellulose (75 ... 78), hemicellulose (9.4 ... 11.9), lignin (3.8), pectin substances (2.9 ... 3 , 2), waxy substances (2.7), nitrogen-containing substances per protein (1.9 ... 2.1), minerals (1.3 ... 2.8) [Krichevsky G.E., Korchagin M.V. ., Senakhov A.V. Chemical technology of textile materials. M., 1985. 640 p.];

- sawdust - waste from the woodworking industry (composition,% of absolutely dry wood: cellulose - 31.0-52.5; lignin - 19.5-30.9; pentosans - 5.3-28.3; mannan - 1, 3-11.3; galactan - 0.7-14.4; uronic acids - 2.9-8.6; substances extracted with hot water - 1.4-22.6; substances extracted with ethyl ether - 0.7 -4.6; ash - 0.2-1.0) [Nikitin V.M., Obolenskaya A.V. Schegolev V.P. Chemistry of wood and cellulose. M .: Forest industry, 1978.-368 S.];

- cotton cellulose [GOST 595-79 "Cotton cellulose. Specifications.];

- wood pulp [GOST 11208-82. Wood pulp (coniferous) sulfate unbleached. Specifications.].

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

Example 1

10 g of wood sawdust is poured into 200 ml of 0, 3M aqueous solution of iodic acid (module 20) at pH 3.5 and subjected to microwave irradiation with a power of 300 W at a frequency of 2.45 GHz and a temperature of 70 ° C for 10 min, then the mass is washed with distilled water to remove unreacted reagents and by-products and treated with 400 ml of a 0.5% sodium bisulfite solution (module 40) at pH 4.5 and room temperature for 0.5 h, then rinsed again with distilled water to remove excess bisulfite and dried.

The treated sorbent is poured into 0.5 L of an aqueous solution at room temperature (module 50) containing 1.5 mmol / L of copper ions. After 15 minutes, the solution is filtered off and the content of Cu (II) ions is determined in the filtrate. The concentration of copper ions in the solution after contacting with the sorbent was 0.284 mmol / L (the degree of extraction of 75.8%).

Example 2

10 g of cotton pulp is poured into 400 ml of a 0.2 M aqueous solution of sodium metaperiodate (module 40) at pH 2.5 and subjected to microwave irradiation with a power of 300 W at a frequency of 2.45 GHz and a temperature of 25 ° C for 7 min, then the mass is washed with distilled water to remove unreacted reagents and by-products and is treated with 150 ml of a 3.5% sodium bisulfite solution (module 15) at pH 2 and room temperature for 1 h, after which it is again washed with distilled water to remove excess bisulfite and dried.

The treated sorbent is poured into 1.5 L of an aqueous solution at room temperature (module 150) containing 0.15 mmol / L of nickel ions. After 1 min, the solution was filtered off and the Ni (II) ion content was determined in the filtrate. The concentration of nickel ions in the solution after contacting with the sorbent was 0.3705 mmol / L (the degree of extraction of 75.3%).

Example 3

10 g of short flaxseed fiber is poured into 150 ml of a 0.1 M aqueous solution of sodium metaperiodate (module 15) at pH 4.5 and subjected to microwave irradiation with a power of 300 W at a frequency of 2.45 GHz and a temperature of 50 ° C for 15 min, then the mass is washed distilled water to remove unreacted reagents and by-products and treated with 500 ml of a 2.0% sodium bisulfite solution (module 50) at pH 4 and room temperature for 0.5 h, then rinsed again with distilled water to remove excess bisulfite and are dried.

The treated sorbent is poured into 2 L of an aqueous solution at room temperature (module 200) containing 1.5 mmol / L of zinc ions. After 10 minutes, the solution is filtered off and the content of Zn (II) ions is determined in the filtrate. The concentration of zinc ions in the solution after contacting with the sorbent was 0.3915 mmol / L (recovery rate 73.9%).

Example 4

10 g of wood pulp is poured into 500 ml of a 0.25 M aqueous solution of sodium hypochlorite (module 50) at pH 3.0 and subjected to microwave irradiation with a power of 300 W at a frequency of 2.45 GHz and a temperature of 30 ° C for 5 min, then the mass is washed with distilled water to remove unreacted reagents and by-products and treated with 300 ml of a 5.0% sodium bisulfite solution (module 30) at pH 4.5 and room temperature for 0.5 h, then rinsed again with distilled water to remove excess bisulfite and dried.

The treated sorbent is poured into 1 l of an aqueous solution at room temperature (module 100) containing 1.5 mmol / l of cadmium ions. After 20 minutes the solution is filtered off and the content of Cd (II) ions is determined in the filtrate. The concentration of cadmium ions in the solution after contacting with the sorbent was 0.408 mmol / L (the degree of extraction of Cd (II) ions was 72.8%).

Example 5

10 g of wood sawdust is poured into 200 ml of a 0.3 M aqueous solution of sodium metaperiodate (module 20) at pH 3.5 and subjected to microwave irradiation with a power of 300 W at a frequency of 2.45 GHz and a temperature of 50 ° C for 10 min, then the mass is washed distilled water to remove unreacted reagents and by-products and treated with 400 ml of a 0.5% sodium bisulfite solution (module 40) at pH 4.5 and room temperature for 0.5 h, then rinsed again with distilled water to remove excess bisulfite and dried.

The treated sorbent is poured into 0.5 l of an aqueous solution at room temperature (module 50) containing 1.5 mmol / l of copper, nickel, zinc and cadmium ions in a ratio of 1: 1: 1: 1. After 20 minutes the solution is filtered off and the content of metal ions is determined in the filtrate. The concentration of Cu (II), Ni (II), Zn (II) and Cd (II) ions in the solution after contacting with the sorbent was 0.091; 0.099;

0.102 and 0.107 mmol / L, respectively (degree of extraction of 75.7; 73.6; 72.8 and 71.5%).

To assess the effectiveness of the method described in the prototype, experiments were conducted on the extraction of heavy metal ions from solutions in which the concentration of heavy metal ions is 1.5 mmol / L, using meal and cake treated with sodium monochloracetic acid.

The results of the experiments are presented in the table.

Thus, from the data given in the table it follows that the proposed method allows to solve the problem, namely: to increase the degree of extraction of heavy metal ions from more concentrated solutions (with a concentration of metal ions of 1.5 mmol / l) by 13-15% and reduce sorption time (from 0.5-1.5 hours to 1-20 minutes).

Table EXAMPLES The degree of extraction,% Sorption time, min Cu ²⁺ Ni ²⁺ Zn ²⁺ Cd ²⁺ one. 77.5 - - - fifteen 2. - 75.3 - - one 3. - - 73.9 - 10 four. - - - 72.8 twenty 5. 75.7 73.6 72.8 71.5 twenty PROTOTYPE 68.1 - - - thirty 62,2 - - 45 - - 60.7 - 60 57.6 90 62.6 60.8 59.7 56.4 90

Claims (3)

1. The method of extraction of heavy metal ions from aqueous solutions by contacting them at room temperature with modified cellulose-based polymer sorbents with a solution / sorbent module of 50-200, characterized in that the sorbents are modified by their interaction with an oxidizing agent under microwave irradiation with power 300 W with a frequency of 2.45 GHz and a temperature of 25-70 ° C for 5-15 minutes, followed by washing with water and treatment with sodium bisulfite, while contacting the modified sorbent by for 1-20 min. 2. The method according to claim 1, characterized in that the interaction of the sorbents with the oxidizing agent is carried out in a solution with a concentration of 0.1-0.3 M at a pH of 2.5-4.5, and the treatment with sodium bisulfite is carried out in a solution with a concentration of 0, 5-5% at a pH of 2-4.5 for 0.5-1 h at room temperature. 3. The method according to claim 1, characterized in that sodium metaperiodate, iodic acid or sodium hypochlorite are used as the oxidizing agent, and cotton or wood pulp, short flax fiber or sawdust are used as polymer sorbents.