RU2702568C1 - Method for modifying cellulose-based sorbents for extracting heavy metal ions from aqueous solutions - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to methods of modifying natural cellulose-containing sorbents designed to extract heavy metal ions from solutions of different composition. Method envisages two-stage treatment of a sorbent selected from cotton or wood pulp, short flax fiber, sawdust or girasol stems. At the first step, treatment is carried out with a solution of an oxidizing agent selected from sodium metaperiodate, iodic acid or sodium hypochlorite. At the second step, treatment is carried out with anthranilic or para-aminobenzoic acid solution at solution pH of 7–10, at temperature 40–45 °C with a solution/sorbent module of 15–50 for 30–60 minutes.

EFFECT: high degree of extraction of heavy metal ions by sorption.

1 cl, 1 tbl, 5 ex

Description

The invention relates to methods for modifying natural cellulose-containing sorbents intended for the extraction of heavy metal ions by sorption 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 aqueous solutions and wastewater of various nature.

A known method of modifying sorbents for the extraction of 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 meal was from 78.3 to 99.9% [Pat. 2258560 Russian Federation, IPC B01J 20/24. The method of extraction of heavy metal ions from aqueous solutions / Nikiforova T.E., Bagrovskaya N.A., Lilin S.A., Kozlov V.A .; Applicant and patent holder Ivan. state chemical techn. University of Chemical Engineering, RAS. - No. 2004102130/15; declared 01/26/04; publ. 08/20/05, Bull. Number 23. - 5 p.].

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.

A known method of modifying sorbents for the extraction of heavy metal ions from aqueous solutions by contacting them at room temperature for 1-20 minutes with polymer sorbents based on cellulose, modified by microwave irradiation with a power of 300 W with a frequency of 2.45 GHz with a solution / sorbent module, equal to 50-200. In this case, the modification of sorbents is carried out by preliminary immersion in an aqueous solution of caprolactam or distillation residue of caprolactam with a concentration of 2-20 g / l at a module of 15-50, followed by extraction and microwave irradiation for 1-5 minutes at a temperature of 150-200 ° C and contacting the modified sorbents with aqueous solutions is carried out at a solution pH of 3-7 [US Pat. 2495830 Russian Federation, IPC С02F 1/62, В01J 20/24. The method of extraction of heavy metal ions from aqueous solutions / Nikiforova T.E., Kozlov V.A., Efimov N.A .; Applicant and patent holder Ivan. state chemical techn. un-t - No. 2012117931/05; declared 04/28/12; publ. 10/20/13, Bull. No. 29. - 7 p.].

However, this method involves the process of modifying sorbents at relatively high temperatures (150-200 ° C).

A known method of modifying sorbents for the extraction of heavy metal ions from aqueous solutions by contacting them at room temperature with modified polymer sorbents based on cellulose with a solution / sorbent module of 50-200, in which the modification of sorbents is carried out 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 modifying sorbent is carried out for 1-20 minutes

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. In this case, 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 [Pat. 2438995 Russian Federation, IPC ⁷ C02F 1/62, 1/28, 101/20, B01J 20/24. The method of extraction of heavy metal ions from aqueous solutions / Nikiforova T.E., Kozlov V.A., Titarenko N.A., Zimin D.M .; Applicant and patent holder Ivan. state chemical techn. un-t - No. 201024986/05; declared 06/17/10; publ. 01/10/12, Bull. No. 1].

However, sorbents modified in this way are not sufficiently capable of recovering heavy metal ions from aqueous solutions with pH <5.

The closest in technical essence and the achieved result, that is, the prototype, is a method for modifying the sorbent used to extract heavy metal ions, involving a two-stage treatment of the initial sorbent selected from cotton or wood pulp, short flax fiber, wood sawdust or Jerusalem artichoke stems, modifying agents , while in the first stage, the treatment is carried out with a solution of an oxidizing agent selected from sodium metaperiodate, iodic acid or sodium hypochlorite, at an oxidizer concentration of 0.1-0.3 M, at a solution pH of 2.5-4.5, with a solution / sorbent module of 15-50, under the influence of microwave irradiation with a power of 300 W with a frequency of 2.45 GHz at a temperature of 25-55 ° C for 5-15 minutes, and in the second stage, the treatment is carried out with a solution of 3-10% sulfanilic acid at a solution pH of 8-10, with a solution / sorbent module of 15-50 at room temperature for 30-60 minutes, and after each stages of processing with a modifying agent, the product is washed with water [US Pat. 2640547 Russian Federation, IPC B01J 20/3085, B01J 20/24. A method for modifying cellulose-based sorbents for the extraction of heavy metal ions from aqueous solutions / T. Nikiforova, V. A. Kozlov; Applicant and patent holder Ivan. state chemical techn. un-t - No. 2016149967; declared 12/19/2016; publ. 01/09/2018, Bull. No. 1].

The disadvantages of the prototype is not a high degree of extraction of heavy metal ions from aqueous solutions (with a concentration of metal ions of 1.5 mmol / l).

The technical result of the invention is to increase the degree of extraction of heavy metal ions.

This result is achieved by the fact that in the method of modifying cellulose-based sorbents for the extraction of heavy metal ions from aqueous solutions, which involves a two-stage treatment of a sorbent selected from cotton or wood pulp, short flax fiber, sawdust or Jerusalem artichoke stalks, modifying agents, followed by washing with water after each stage, while in the first stage, an oxidizing agent solution selected from sodium metaperiodate, iodic acid or hypochlorite is treated sodium, at an oxidizing agent concentration of 0.1-0.3 M, at a solution pH of 2.5-4.5, with a solution / sorbent module of 15-50, at a temperature of 25-55 ° C, and in the second stage, processing is carried out with the module solution / sorbent 15-50 for 30-60 minutes, according to the invention, in the first stage, the treatment of the sorbent with an oxidizing agent is carried out until the content of aldehyde groups in the sorbent is 5-10% for 2-4 hours, and in the second stage the processing is carried out 1-10% a solution of anthranilic or para-aminobenzoic acid at a solution pH of 7-10, a temperature of 40-45 ° C with stirring.

The following reagents are used to carry out the claimed invention:

- 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 hydroxide NaOH [GOST 2263-79. Technical caustic soda. Specifications.]

- Anthranilic acid - C ₇ H ₇ O ₂ N [GOST 14310-78 Technical 2-aminobenzoic acid. Technical conditions (as Amended by N 1, 2, 3)].

Structural formula:

4-Aminobenzoic acid (bacterial vitamin H ₁ , vitamin B ₁₀ , para-aminobenzoic acid (PABA), C ₇ H ₇ NO ₂ CAS: 150-13-0.

Structural formula:

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 p.];

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

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

- Jerusalem artichoke stalks are agricultural waste of the following composition (in terms of dry matter): 55.8% carbohydrates (cellulose, hemicellulose, inulin, pectin substances), 10% protein, 18.1% nitrogen-free extractive substances 14.3% mineral substances and 1.8% fat [Ryazanova, T.V. The chemical composition of the vegetative part of Jerusalem artichoke and its use / T.V. Ryazanova, N.A. Chuprova, L.A. Dorofeeva, A.V. Bogdanov // Forest Journal. - 1997. - No. 4. - S. 71-75].

Jerusalem artichoke stalks are cleaned of the outer layer and crushed.

The invention is as follows.

Stage 1: Oxidation of the sorbent based on cellulose (sodium metaperiodate, iodic acid or sodium hypochlorite) with the formation of dialdehyde cellulose is carried out to the content of aldehyde groups in the sorbent 5-10% as follows.

In a glass container made of dark glass with a capacity of 0.5 l with a ground stopper, 10 g (~ 0.06 mol) of a cellulose-based sorbent was placed and 1 l of an aqueous 0.1 n oxidizing agent solution (pH ≈ 4) was poured, it was thoroughly shaken and placed in a dark place, and samples were periodically taken for analysis. At the end of the reaction, the oxidized sorbent was filtered off from the solution and washed successively with water and acetone and dried in the dark at room temperature. The content of aldehyde groups in the oxidized sorbent was determined by iodometric titration [Vasiliev, V.P. Analytical chemistry. Laboratory workshop: textbook. manual for universities chemical-technol. profile / V.P. Vasiliev, R.P. Morozova, L.A. Kochergin; under the editorship of V.P. Vasilieva. - 2nd ed., Revised. and add. - M.: Bustard, 2004. - 415 s].

2 stage. The oxidized sorbent is treated with a 1-10% solution of anthranilic or para-aminobenzoic acid at a solution pH of 7-10, a temperature of 40-45 ° C with stirring.

Example 1

10 g of wood sawdust is poured into 200 ml of a 0.3 M aqueous solution of iodic acid (module 20) at pH 3.5 and exposed to an oxidizing agent at 30 ° C for 2 hours, then the mass is washed with distilled water to remove unreacted reagents and by-products , in the second stage, pour 150 ml of a 5% solution of anthranilic acid (module 15), which is adjusted with a NaOH solution to pH 9 and treated at 45 ° C for 60 minutes, after which it is again washed with distilled water to remove excess anthranilic acid and dried.

The treated sorbent with an aldehyde content of 5% 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 0.2985 mmol / L (extraction rate 80.1%).

Example 2

10 g of cotton cellulose is poured into 400 ml of a 0.2 M aqueous solution of sodium metaperiodate (module 40) at pH 2.5 and exposed to an oxidizing agent at 25 ° C for 3 hours, then the mass is washed with distilled water to remove unreacted reagents and by-products, pour 500 ml of a 3% solution of para-aminobenzoic acid (module 50), which is adjusted with a NaOH solution to pH 8.5 and treated at 42 ° C for 45 minutes, then rinsed again with distilled water to remove excess para-aminobenzoic acid and having dried dissolved.

The treated sorbent with an aldehyde content of 7% is poured into 150 ml of an aqueous solution at room temperature (module 15) containing 1.5 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 0.3405 mmol / L (recovery rate 77.3%).

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 exposed to an oxidizing agent at 55 ° C for 3.5 hours, then the mass is washed with distilled water to remove unreacted reagents and by-products, pour 300 ml of a 7% solution of anthranilic acid (module 30), which is adjusted with a NaOH solution to pH 10 and treated at 43 ° C for 50 minutes, after which it is again washed with distilled water to remove excess anthranilic acid and dried.

A treated sorbent with an aldehyde group content of 8% 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 0.3465 mmol / L (recovery rate 76.9%).

Example 4

10 g of wood pulp is poured into 250 ml of a 0.15 M aqueous solution of sodium hypochlorite (module 25) at pH 3 and exposed to an oxidizing agent at 35 ° C for 4 hours, then the mass is washed with distilled water to remove unreacted reagents and by-products, pour 200 ml of a 10% solution of para-aminobenzoic acid (module 20), which is adjusted with a NaOH solution to pH 8 and treated at 44 ° C for 35 minutes, after which it is again washed with distilled water to remove excess para-aminobenzoic acid and dried.

The treated sorbent with an aldehyde group content of 10% 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 0.3495 mmol / L (the degree of extraction of Cd (II) ions is 76.7%).

Example 5

10 g of ground Jerusalem artichoke stalks are poured into 500 ml of a 0.25 M aqueous solution of sodium metaperiodate (module 50) at pH 4 and exposed to an oxidizing agent at a temperature of 45 ° C for 2.5 hours, then the mass is washed with distilled water to remove unreacted reagents and side products, pour 400 ml of a 1% solution of anthranilic acid (module 40), which is adjusted with a NaOH solution to pH 7 and treated at 40 ° C for 30 minutes, after which it is again washed with distilled water to remove excess anthranilic acid and dried yut.

The treated sorbent with an aldehyde group content of 6% 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 0.339; 0.3705; 0.3765 and 0.3555 mmol / L, respectively (degree of extraction of 77.4; 75.3; 74.9 and 76.3%).

The results of studies on the extraction of heavy metal ions from solutions with a concentration of heavy metal ions of 1.5 mmol / L according to the prototype and according to the claimed invention are presented in the table.

Thus, from the data 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 solutions (with a concentration of metal ions of 1.5 mmol / l) by 2-5%.

Claims (1)

A method of modifying cellulose-based sorbents to extract heavy metal ions from aqueous solutions, comprising a two-stage treatment of a sorbent selected from cotton or wood pulp, short flax fiber, wood sawdust or Jerusalem artichoke stalks, modifying agents, followed by washing with water after each stage, while the first stage is treated with a solution of an oxidizing agent selected from sodium metaperiodate, iodic acid or sodium hypochlorite, at an oxidizing agent concentration of 0.1-0.3 M, at a solution pH of 2.5-4.5, with a solution / sorbent module of 15-50, at a temperature of 25-55 ° C, and in the second stage, processing is carried out with a solution / sorbent module of 15-50 for 30-60 minutes, characterized the fact that in the first stage the treatment of the sorbent with an oxidizing agent is carried out until the content of aldehyde groups in the sorbent is 5-10% for 2-4 hours, and in the second stage, the treatment is carried out with a 1-10% solution of anthranilic or para-aminobenzoic acid at a pH of 7-10 , temperature 40-45 ° С with stirring.