RU2792209C1 - Method of modifying sorbents for extraction of heavy metal ions from aqueous solutions - Google Patents

Abstract

FIELD: chemical industry.

SUBSTANCE: invention relates to the chemical industry and may be used to improve membrane and sorption technologies, in water treatment, in the development of technologies for the utilization of heavy metal ions from aqueous solutions and wastewater of various origin. A method for modifying sorbents for the extraction of heavy metal ions from aqueous solutions is presented, the method consisting in bringing them into contact at room temperature with modified polymeric sorbents based on cellulose at a solution/sorbent modulus of 50-200 during 20-30 min, wherein modifying of sorbents is carried out by depositing carbon nanotubes (CNTs) Taunit M on them, the tubes being pre-oxidized with concentrated nitric acid at a modulus of 50-100 at room temperature during 60-90 minutes or with solutions of potassium dichromate or potassium permanganate at pH 2-4, the modulus of the solution being 50-100 and temperature 50-60°C during 20-30 min, then the nanotubes are separated, washed with distilled and dried, then the modification of cellulose-based sorbents is carried out with treated carbon nanotubes in an amount of 10-20% of the mass of the sorbent in toluene at a toluene/sorbent modulus of 1-2 at room temperature during 1-2 hours, then the finished sorbent is separated from toluene by centrifugation, washed with distilled water and dried, wherein the cellulose sorbents treated in an alkali solution are treated with a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, a temperature of 50-70°C for 2-3 hours at a modulus of 15, followed by washing with distilled water and ethyl alcohol to pH 7, then treated with ethylenediamine at a temperature of 75-80°C under reflux during 2.5-3.5 h at ethylenediamine/sorbent 2 module, followed by washing with distilled water and drying to permanent weight.

EFFECT: invention provides an increase in the degree of extraction of heavy metal ions.

1 cl, 1 tbl, 9 ex

Description

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

A known method of purification of industrial wastewater from heavy metals, in particular from copper ions, by sorption on sawdust treated with 4-methyl-8-oxo-5-azadecadiene-3,9-OH-2 at a mass ratio of sawdust - reagent 1 : 0.05÷0.1 [A.s. 1819669 USSR, MKI ⁵ B01J 20/22. Method for obtaining a sorbent for copper wastewater treatment // Timofeeva S.S., Kukharev B.F., Stankevich V.K., Klimenko G.R. - No. 4911863/05; dec. 05/15/91.; publ. 7.06.93, Bull. No. 21.].

A method is known for extracting heavy metal ions from aqueous solutions by contacting them at room temperature for 1-20 min with cellulose-based polymeric sorbents modified by microwave irradiation with a power of 300 W at a frequency of 2.45 GHz with a solution/sorbent modulus of 50- 200. At the same time, the modification of sorbents is carried out by their preliminary immersion in an aqueous solution of caprolactam or distillation residue of caprolactam with a concentration of 2-20 g/l at a modulus of 15-50, followed by squeezing and microwave irradiation for 1-5 minutes at a temperature of 150-200°C , and the contact of the modified sorbents with aqueous solutions is carried out at a solution pH of 3-7 [Patent No. 2495830 RF, IPC C02F 1/28, 1/62; B01J 20/24, 20/32. A method for extracting heavy metal ions from aqueous solutions / Nikiforova T.E., Kozlov V.A., Efimov N.A.; applicant and patent holder State Educational Institution of Higher Professional Education "Ivanovo State University of Chemistry and Technology" (GOUVPO "IGKhTU") (RU). - No. 2012117931/05, 04/28/2012; publ. 20.10.2013, Bull. No. 29].

A known method of extracting heavy metal ions from aqueous solutions by contacting them at room temperature for 1-20 min with modified polymeric sorbents based on cellulose at a solution / sorbent modulus of 50-200, in which the modification of sorbents is carried out by applying carbon nanotubes to them under ultrasonic exposure with an operating frequency of 35 kHz at room temperature for 2–10 min in an aqueous solution containing 3–12% polyacrylic acid and 0.1–1% nanotubes of the mass of the sorbent with a solution / sorbent module of 10, followed by processing of the sorbents in acrylic acid solution in the presence of an initiator at a temperature of 60-90ºС with stirring for 30-90 min, while the processing of sorbents with deposited carbon nanotubes is carried out in a solution with an acrylic acid content of 15-25% and an ammonium persulfate initiator of 1.5-2.5 % by weight of the sorbent at a solution / sorbent module of 10, followed by washing, squeezing and drying for about humidity 14% [US Pat. 2598483 RF, IPC С02F 1/28, 1/62, B01J 20/00. A method for extracting heavy metal ions from aqueous solutions / Nikiforova T.E., Kozlov V.A., Natareev S.V., Gainullina A.M.; applicant and patent holder Ivan. state chemical tech. un-t. - No. 2015125938/05; dec. 06/29/2015; publ. 27.09.2016, Bull. No. 27].

However, when using these methods, an insufficiently high degree of extraction of heavy metal ions is achieved. In addition, the use of ultrasonic treatment of sorbents, which requires special equipment, is envisaged.

The closest in technical essence and the achieved result, that is, the prototype, is a method for modifying sorbents for extraction of heavy metal ions from aqueous solutions, which consists in contacting them at room temperature with modified polymeric sorbents based on cellulose with a solution / sorbent modulus of 50-200, while modifying the sorbents is carried out by applying Taunit-M carbon nanotubes on them, moreover, carbon nanotubes are preliminarily oxidized with concentrated nitric acid at a modulus of 50–100 at room temperature for 60–90 min or with solutions of potassium bichromate or potassium permanganate at pH 2–4, solution modulus 50–100 and a temperature of 50–60°C for 20 -30 min, then the carbon nanotubes are separated, washed with distilled water, dried and treated with thionyl chloride at a thionyl chloride / CNT module of 30-50 when heated under reflux at a temperature of 75-80°C for 15-20 min, followed by washing, squeezing and drying to constant weight, after which polymeric sorbents based on cellulose are modified with treated and carbon nanotubes in an amount of 10-20% of the mass of the sorbent in toluene at a toluene/sorbent modulus of 1-2 at room temperature for 1-2 hours, then the finished sorbent is squeezed out or separated by centrifugation from toluene, washed with distilled water and dried, and contacting them with modified polymeric sorbents based on cellulose is carried out for 20-30 min [US Pat. 2768623 RF, IPC C 1 51, B 01 J 20/24, B 01 J 20/32, C02F 1/28. The method of modifying sorbents for the extraction of heavy metal ions from aqueous solutions [Text] / Nikiforova T.E., Kozlov V.A., Natareev S.V., Vokurova D.A.; applicant and patent holder Ivan. state chemical tech. un-t. - No. 2021116849; dec. 06/10/2021; publ. 03/24/2022, Bull. No. 9].

The disadvantage of the prototype is not sufficiently high degree of extraction of heavy metal ions;

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 sorbents for the extraction of heavy metal ions from aqueous solutions, which consists in contacting them at room temperature with modified polymeric sorbents based on cellulose at a solution/sorbent modulus of 50–200 for 20–30 min, while modifying the sorbents is carried out by applying carbon nanotubes "Taunit M" on them. which are pre-oxidized with concentrated nitric acid at a modulus of 50-100 at room temperature for 60-90 minutes or with solutions of potassium dichromate or potassium permanganate at pH 2-4, solution modulus 50-100 and a temperature of 50-60 ° C for 20-30 min, then the nanotubes are separated, washed with distilled water, and the modification of sorbents based on cellulose is carried out with treated carbon nanotubes in an amount of 10–20% of the mass of the sorbent in toluene at a toluene/sorbent modulus of 1–2 at room temperature for 1–2 h , then the finished sorbent is separated from toluene by centrifugation , washed with distilled water and dried; h at a module of 15, followed by washing with distilled water and ethyl alcohol to pH 7, then treated with ethylenediamine at a temperature temperature 75-80°C under reflux for 2.5-3.5 h at the module ethylenediamine / sorbent 2, followed by washing with distilled water and drying to constant weight.

To implement the proposed method for extracting heavy metal ions from aqueous solutions, the following reagents are used:

- carbon nanotubes (CNT) "Taunit-M" (TU 2166-001-02069289-2006, NanoTechCenter LLC).

Carbon nanomaterial "Taunit-M" is one-dimensional nanoscale filamentous formations of polycrystalline graphite with a length of more than 2 microns with outer diameters from 15 to 40 nm in the form of a free-flowing black powder.

- epichlorohydrin GOST 12844-74 Technical epichlorohydrin. Specifications.

- ethyl alcohol rectified from food raw materials GOST 5962-2013. Specifications

- nitric acid . GOST 701-89 Concentrated nitric acid. Specifications.

- potassium bichromate GOST 2652-78 Potassium bichromate Technical. Specifications

- potassium permanganate . GOST 5777-84. Potassium permanganate technical. Specifications.

- sodium hydroxide GOST R 55064-2012 technical caustic soda. Specifications.

- ethylenediamine TU 6-02-622-86 Technical ethylenediamine. Specifications.

The following were used as sorbents:

- short flax fiber, which is a secondary product of the processing of 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 in terms of proteins (1.9 ... 2.1), mineral substances (1.3 ... 2.8) [Krichevsky G.E., Korchagin M.V. ., Senakhov A.V. Chemical technology of textile materials. M., 1985. 640 p.];

- sawdust - a waste of 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; hot water extractables - 1.4-22.6; ethyl ether extractables - 0.7 -4.6; ash - 0.2-1.0) [Nikitin V.M., Obolenskaya A.V. Shchegolev V.P. Chemistry of wood and cellulose. M.: Timber industry, 1978. - 368 p.];

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

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

- Jerusalem artichoke stalks are a waste of agricultural production of the following composition (in terms of dry matter): 55.8% carbohydrates (cellulose, hemicelluloses, inulin, pectin substances), 10% proteins, 18.1% nitrogen-free extractive substances 14.3% mineral substances and 1.8% fats [Ryazanova, T.V. 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 from the outer layer and crushed.

The invention is carried out as follows.

Example 1

(Stage 1)

1 g of CNT "Taunit-M" is poured into 100 ml of concentrated nitric acid (module 100) and oxidized at room temperature for 60 minutes. Then nitric acid is separated from the nanotubes by decantation (or filtration), the CNTs are washed with distilled water and dried.

(stage 2)

10 g of sawdust treated in an alkali solution (NaOH concentration 10 g/l) are treated in 150 ml (module 15) of a mixture of epichlorohydrin and ethanol at a ratio of 1:2, at a temperature of 70°C for 2.5 hours, followed by washing distilled water and ethanol to pH 7, then treated with ethylenediamine at 78° C. under reflux for 3 hours at ethylenediamine/cellulose module 2, followed by washing with distilled water and drying to constant weight.

(stage 3)

2 g of oxidized CNT "Taunit-M" (20% by weight of the sorbent) are placed in a beaker containing 20 ml of toluene, and dissolved with stirring. Then, 10 g of sawdust treated with epichlorohydrin and ethylenediamine (toluene/sorbent 2 module) are added to the resulting solution and incubated for 1 hour at room temperature. The finished sorbent is separated by centrifugation from toluene, washed with distilled water and dried.

The modified sorbent is poured into 0.5 l of an aqueous solution at room temperature (module 50), pH 5, containing 1.5 mmol/l of copper ions. After 20 min, the solution is filtered off and the content of Cu(II) ions in the filtrate is determined.

The concentration of copper ions in the solution after contact with the sorbent was 0.2325 mmol/l (extraction rate 84.5%).

Example 2

(Stage 1)

1 g of CNT "Taunit-M" is poured into 50 ml of a 0.1N solution of potassium permanganate (module 50) and oxidized at a temperature of 60°C and pH 2 for 20 min. Then the solution is separated from the nanotubes by decantation (or filtration), the CNTs are washed with distilled water and dried.

(stage 2)

10 g of cotton cellulose treated in an alkali solution (NaOH concentration 7 g/l) are treated in 150 ml (module 15) of a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, at a temperature of 60°C for 2.5 hours, followed by washing distilled water and ethanol to pH 7, then treated with ethylenediamine at a temperature of 77°C under reflux for 3.5 h at the module ethylenediamine/cellulose 2, followed by washing with distilled water and drying to constant weight.

(stage 3)

2 g of oxidized CNT "Taunit-M" (20% by weight of the sorbent) are placed in a beaker containing 10 ml of toluene, and dissolved with stirring. Then, 10 g of cotton cellulose treated with epichlorohydrin and ethylenediamine (toluene/sorbent module 1) are added to the resulting solution and incubated for 2 hours at room temperature. The finished sorbent is separated by centrifugation from toluene, washed with distilled water and dried.

The modified sorbent is poured into 1.5 l of an aqueous solution at room temperature (module 150), pH 3, containing 1.5 mmol/l of nickel ions. After 25 min, the solution is filtered off and the content of Ni(II) ions in the filtrate is determined. The concentration of nickel ions in the solution after contact with the sorbent was 0.2595 mmol/l (extraction rate 82.7%).

Example 3

(Stage 1)

1 g of CNT "Taunit-M" is poured into 100 ml of 0.1 N solution of potassium bichromate (module 100) and their oxidation is carried out at a temperature of 50°C and pH 4 for 30 min. Then the solution is separated from the nanotubes by decantation (or filtration), the CNTs are washed with distilled water and dried.

(stage 2)

10 g of short flax fiber treated in an alkali solution (NaOH concentration 8 g/l) is treated in 150 ml (module 15) of a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, at a temperature of 65°C for 2 hours, followed by washing with distilled water and ethanol to pH 7, then treated with ethylenediamine at 76° C. under reflux for 3 hours at ethylenediamine/cellulose 2 module, followed by washing with distilled water and drying to constant weight.

(stage 3)

2 g of oxidized CNT "Taunit-M" (20% by weight of the sorbent) are placed in a beaker containing 20 ml of toluene, and dissolved with stirring. Then, 10 g of short flax fiber treated with epichlorohydrin and ethylenediamine (toluene/sorbent 2 module) is added to the resulting solution and kept for 1 hour at room temperature. The finished sorbent is separated by centrifugation from toluene, washed with distilled water and dried.

The modified sorbent is poured into 2 l of an aqueous solution at room temperature (module 200), pH 6, containing 1.5 mmol/l of zinc ions. After 30 min, 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 contact with the sorbent was 0.2295 mmol/l (extraction rate 84.7%).

Example 4

(Stage 1)

1 g of CNT "Taunit-M" is poured into 50 ml of concentrated nitric acid (module 50) and oxidized at room temperature for 90 minutes. Then nitric acid is separated from the nanotubes by decantation (or filtration), the CNTs are washed with distilled water and dried.

(stage 2)

10 g of wood pulp treated in an alkali solution (NaOH concentration 5 g/l) is treated in 150 ml (module 15) of a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, at a temperature of 50°C for 2 hours, followed by washing with distilled water and ethyl alcohol to pH 7, then treated with ethylenediamine at 79° C. under reflux for 3 hours at an ethylenediamine/cellulose module of 2, followed by washing with distilled water and drying to constant weight.

(stage 3)

1 g of oxidized CNT "Taunit-M" (10% by weight of the sorbent) is placed in a beaker containing 10 ml of toluene, and dissolved with stirring. Then, 10 g of wood pulp treated with epichlorohydrin and ethylenediamine (toluene/sorbent module 1) is added to the resulting solution and kept for 2 hours at room temperature. The finished sorbent is separated by centrifugation from toluene, washed with distilled water and dried.

The modified sorbent is poured into 1 l of an aqueous solution at room temperature (module 100), pH 7, containing 1.5 mmol/l of cadmium ions. After 23 min, 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 contact with the sorbent was 0.2505 mmol/l (the degree of extraction of Cd(II) ions was 83.3%).

Example 5

(Stage 1)

1 g of CNT "Taunit-M" is poured into 100 ml of a 0.1 N solution of potassium permanganate (module 100) and oxidized at a temperature of 50°C and pH 4 for 30 min. Then the solution is separated from the nanotubes by decantation (or filtration), the CNTs are washed with distilled water and dried.

(stage 2)

10 g of Jerusalem artichoke stems treated in an alkali solution (NaOH concentration 0.05 g/l) are treated in 150 ml (module 15) of a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, at a temperature of 70°C for 2.5 hours followed by washing with distilled water and ethanol to pH 7, then treating with ethylenediamine at 75° C. under reflux for 3 hours at an ethylenediamine/cellulose module of 2, followed by washing with distilled water and drying to constant weight.

(stage 3)

1 g of oxidized CNT "Taunit-M" (10% by weight of the sorbent) is placed in a beaker containing 20 ml of toluene, and dissolved with stirring. Then, 10 g (toluene/sorbent 2 module) of Jerusalem artichoke stalks treated with epichlorohydrin and ethylenediamine are added to the resulting solution and kept for 1 hour at room temperature. The finished sorbent is separated by centrifugation from toluene, washed with distilled water and dried.

The modified sorbent is poured into 0.6 l of an aqueous solution at room temperature (module 60), pH 5, containing 1.5 mmol/l of cadmium ions. After 26 min, 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 contact with the sorbent was 0.243 mmol/l (extraction rate 83.8%).

Example 6

(stage 1) 1 g of CNT "Taunit-M" is poured into 50 ml of 0.1 N solution of potassium bichromate (module 50) and their oxidation is carried out at a temperature of 60°C and pH 2 for 20 min. Then the solution is separated from the nanotubes by decantation (or filtration), the CNTs are washed with distilled water and dried.

(stage 2) 10 g of cotton cellulose treated in an alkali solution (NaOH concentration 3 g/l) is treated in 150 ml (module 15) of a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, at a temperature of 50°C for 3 hours, followed by rinsing with distilled water and ethanol to pH 7, then treating with ethylenediamine at 75° C. under reflux for 3.5 hours at ethylenediamine/cellulose module 2, followed by rinsing with distilled water and drying to constant weight.

(stage 3)

1 g of oxidized CNT "Taunit-M" (10% by weight of the sorbent) is placed in a beaker containing 20 ml of toluene, and dissolved with stirring. Then, 10 g (toluene/sorbent 2 module) of cotton cellulose treated with epichlorohydrin and ethylenediamine are added to the resulting solution and kept for 2 hours at room temperature. The finished sorbent is separated by centrifugation from toluene, washed with distilled water and dried.

The modified sorbent is poured into 0.75 l of an aqueous solution at room temperature (module 75), pH 6, containing 1.5 mmol/l of copper, nickel, zinc and cadmium ions in a ratio of 1:1:1:1. After 28 min, the solution is filtered off and the content of metal ions in the filtrate is determined.

The concentration of Cu(II), Ni(II), Zn(II) and Cd(II) ions in the solution after contact with the sorbent was 0.297; 0.306; 0.3105 and 0.336 mmol/l, respectively (extraction 80.2; 79.6; 79.3 and 77.6%).

Example 7

(Stage 1)

1 g of CNT "Taunit-M" is poured into 75 ml of concentrated nitric acid (module 75) and oxidized at room temperature for 75 minutes. Then nitric acid is separated from the nanotubes by decantation (or filtration), the CNTs are washed with distilled water and dried.

(stage 2) 10 g of sawdust treated in an alkali solution (NaOH concentration 9 g/l) is treated in 150 ml (module 15) of a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, at a temperature of 70°C for 2 hours followed by washing with distilled water and ethanol to pH 7, then treating with ethylenediamine at 80° C. under reflux for 3 hours at an ethylenediamine/cellulose module of 2, followed by washing with distilled water and drying to constant weight.

(stage 3)

2 g of oxidized CNT "Taunit-M" (20% by weight of the sorbent) are placed in a beaker containing 10 ml of toluene, and dissolved with stirring. Then, 10 g of sawdust treated with epichlorohydrin and ethylenediamine (toluene/sorbent module 1) are added to the resulting solution and incubated for 1 hour at room temperature. The finished sorbent is separated by centrifugation from toluene, washed with distilled water and dried.

The modified sorbent is poured into 0.8 l of an aqueous solution at room temperature (module 80), pH 5, containing 1.5 mmol/l of copper ions. After 27 min, the solution is filtered off and the content of Cu(II) ions in the filtrate is determined.

The concentration of copper ions in the solution after contact with the sorbent was 0.2265 mmol/l (the recovery rate was 84.9%).

Example 8

(stage 1) 1 g of CNT "Taunit-M" is poured into 75 ml of a 0.1N solution of potassium permanganate (module 75) and oxidized at a temperature of 55°C and pH 3 for 25 min. Then the solution is separated from the nanotubes by decantation (or filtration), the CNTs are washed with distilled water and dried.

(stage 2) 10 g of wood pulp treated in an alkali solution (NaOH concentration 2 g/l) is treated in 150 ml (module 15) of a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, a temperature of 50°C for 2.5 h followed by washing with distilled water and ethanol to pH 7, then treated with ethylenediamine at a temperature of 80°C under reflux for 2.5 h at a modulus of ethylenediamine / cellulose 2, followed by washing with distilled water and drying to constant weight.

(stage 3) 1 g of oxidized CNT "Taunit-M" (10% by weight of the sorbent) is placed in a beaker containing 20 ml of toluene, and dissolved with stirring. Then, 10 g of wood cellulose treated with epichlorohydrin and ethylenediamine (toluene/sorbent 2 module) are added to the resulting solution and incubated for 1 h at room temperature. The finished sorbent is separated by centrifugation from toluene, washed with distilled water and dried.

The modified sorbent is poured into 1.25 l of an aqueous solution at room temperature (module 125), pH 3, containing 1.5 mmol/l of nickel ions. After 21 min, the solution is filtered off and the content of Ni(II) ions is determined in the filtrate. The concentration of nickel ions in the solution after contact with the sorbent was 0.264 mmol/l (extraction rate 82.4%).

Example 9

(stage 1) 1 g of CNT "Taunit-M" is poured into 80 ml of 0.1 N solution of potassium bichromate (module 80) and their oxidation is carried out at a temperature of 58°C and pH 3.5 for 28 minutes. Then the solution is separated from the nanotubes by decantation (or filtration), the CNTs are washed with distilled water and dried.

(stage 2) 10 g of short flax fiber treated in an alkali solution (NaOH concentration 6 g/l) is treated in 150 ml (module 15) of a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, at a temperature of 60°C for 3 hours followed by washing with distilled water and ethanol to pH 7, then treated with ethylenediamine at 80° C. under reflux for 3 hours at an ethylenediamine/cellulose module of 2, followed by washing with distilled water and drying to constant weight.

(stage 3) 2 g of oxidized CNT "Taunit-M" (20% by weight of the sorbent) is placed in a beaker containing 20 ml of toluene, and dissolved with stirring. Then, 20 g of short flax fiber treated with epichlorohydrin and ethylenediamine (toluene/sorbent module 1) is added to the resulting solution and kept for 1 hour at room temperature. The finished sorbent is separated by centrifugation from toluene, washed with distilled water and dried.

The modified sorbent is poured into 1.8 l of an aqueous solution at room temperature (module 180), pH 6, containing 1.5 mmol/l of zinc ions. After 29 min, 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 contact with the sorbent was 0.231 mmol/l (extraction rate 84.6%).

The results of the experiments in comparison with the prototype are presented in the table.

Table EXAMPLES Degree
extraction, % Cu2 ⁺ Ni2 ⁺ Zn2 ⁺ CD ²⁺ 1. 84.5 - - - 2. - 82.7 - - 3. - - 84.7 - 4. - - - 83.3 5. - - - 83.8 6. 80.2 79.6 79.3 77.6 7. 84.9 8. 82.4 9. 84.6 PROTOTYPE 1 83.4 - - - 2 - 81.2 - - 3 - - 83.3 - 4 - - - 80.8 5 - - - 80.7 6 79.1 78.3 78.1 73.9 7 83.5 8 81.1 9 83.2

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 by 1-5%.

Claims (1)

A method for modifying sorbents for the extraction of heavy metal ions from aqueous solutions, which consists in contacting them at room temperature with modified cellulose-based polymeric sorbents at a solution/sorbent modulus of 50-200 for 20-30 minutes, while modifying the sorbents is carried out by application of carbon nanotubes (CNT) Taunit M on them, which are pre-oxidized with concentrated nitric acid at a modulus of 50-100 at room temperature for 60-90 minutes or with solutions of potassium dichromate or potassium permanganate at pH 2-4, solution modulus 50-100 and temperature of 50–60°C for 20–30 min, then the nanotubes are separated, washed with distilled water, and the sorbents based on cellulose are modified with treated carbon nanotubes in an amount of 10–20% of the mass of the sorbent in toluene at a toluene/sorbent modulus of 1 -2 at room temperature for 1-2 hours, then the finished sorbent is separated from toluene by centrifugation ion, washed with distilled water and dried, characterized in that the cellulose sorbents treated in an alkali solution are treated with a mixture of epichlorohydrin and ethyl alcohol at a ratio of 1:2, a temperature of 50-70 ° C for 2-3 hours at a module of 15, followed by washing distilled water and ethanol to pH 7, then treated with ethylenediamine at a temperature of 75-80°C under reflux for 2.5-3.5 hours at the ethylenediamine/sorbent 2 module, followed by washing with distilled water and drying to constant weight.