RU2471721C1 - Method of modifying cellulose-based sorbents - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used for improvement of membrane and sorption technologies, in water preparation, in elaboration of technologies for utilisation of ions of heavy metals from water solutions and sewage waters. Method of modification of cellulose-based sorbents includes their successive treatment with solutions of oxidiser, hydroxylamine hydrochloride, hydrogen peroxide and sodium hydroxide with washing with water after each stage. Interaction of sorbents with oxydiser is realised with microwave irradiation with power 300 W, with frequency 2.45 GHz and temperature 25-55°C for 5-15 minutes in solution with concentration 0.1-0.3 M at pH 2.5-4.5 and module solution/sorbent 15-50. Treatment with hydroxylamine hydrochloride is carried out with 0.3-1 M water solution at pH 3-5, module solution/sorbent 15-50 for 40-60 min. treatment with hydrogen peroxide id performed with its 30% solution at pH 5-7 for 30-60 min at room temperature and module solution/sorbent 15-50. Treatment with sodium hydroxide solution is carried out at pH 8-9 for 5 min at room temperature. As oxidiser preferably used is sodium metaperiodate, periodic acid or sodium hypochlorite, and as sorbents - cotton or wood cellulose, short flax fibre or sawdust.

EFFECT: invention makes it possible to increase degree of extraction of ions of heavy metals from solutions with concentration of metal ions to 1,5 mmol/l by 13-15% and reduce sorption time to 1-20 min.

2 cl, 1 tbl, 5 ex

Description

FIELD OF TECHNOLOGY

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 various 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.

BACKGROUND

A known method of modifying wood sawdust, which consists in processing 4-methyl-8-oxo-5-azadecadiene-3,9-OH-2 with a mass ratio of sawdust to reagent 1: 0.05-0.1 [A.S. USSR 1819669, MKI ⁵ V 01 J 20/22. 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; declared 05/15/91; publ. 06/07/93, Bull. No. 21]. The modified sorbent is intended for sorption treatment of wastewater of industrial enterprises from heavy metals, in particular from copper ions.

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 modifying 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. Sorbents are designed to extract heavy metal ions from aqueous solutions. As a result of the use of such modified 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% [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 modification 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 of modifying cellulose-based sorbents, which are used as secondary products of the processing of oilseeds - oilseed meal or meal, pretreated in an aqueous solution containing 1- monochloracetic acid sodium salt 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 for 30-60 minutes in a boiling water bath, after which a diluted solution is added strongly mineral acid (HCl or H ₂ SO ₄₎ to pH 4-7 [Nikiforov TE, VA Kozlov, M. Rodionova The method of extraction of heavy metal ions from aqueous solutions. RF patent No. 2329098. Publ. in BI No. 20 of July 20, 2008]. Modified sorbents are designed to extract heavy metal ions from aqueous solutions by contacting them at room temperature with an aqueous solution containing heavy metal ions for 0.5-1.5 hours with a solution / sorbent module equal to 50-200.

The disadvantages of the prototype are:

a) insufficiently high degree of extraction of heavy metal ions (56.4-68.1%) from concentrated solutions (with a concentration of metal ions of 1.5 mmol / l); b) a long sorption time (0.5-1.5 hours).

SUMMARY OF THE INVENTION

The objective of the invention is to provide a method of modifying sorbents based on cellulose to extract heavy metal ions from aqueous solutions, allowing:

a) increase the degree of extraction of heavy metal ions from concentrated solutions (with a concentration of metal ions of 1.5 mmol / l); b) reduce sorption time.

The problem is solved by creating a method of modifying cellulose-based sorbents designed to extract heavy metal ions from aqueous solutions by treating them with modifying agents, in which the modification is carried out by sequentially treating them with solutions of an oxidizing agent, hydroxylamine hydrochloride, hydrogen peroxide and sodium hydroxide with water washing after each stage, moreover, the interaction of sorbents with an oxidizing agent is carried out under microwave irradiation with a power of 300 W with a frequency 2.45 GHz and a temperature of 25-55 ° C for 5-15 minutes in a solution with a concentration of 0.1-0.3 M at a pH of 2.5-4.5, and a solution / sorbent module of 15-50; treatment with hydroxylamine hydrochloride, it is carried out with a 0.3 - 1 M aqueous solution at pH 3-5, the solution / sorbent module is 15-50, for 40-60 minutes at room temperature; Hydrogen peroxide oxidation is carried out with its 30% solution at pH 5-7 for 30-60 minutes at room temperature, the solution / sorbent module is 15-50, and treatment with sodium hydroxide solution is performed at pH 8-9 for 5 minutes at room temperature temperature, while contacting the modified sorbent is carried out for 1-20 minutes

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 sorbents.

The extraction of heavy metal ions from aqueous solutions is carried out by contacting them at room temperature with modified cellulose-based polymer sorbents with a solution / sorbent module of 50-200.

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. Technical conditions];

- hydroxylamine hydrochloride - (NH ₃ OH) Cl [GOST 5456-79. Hydroxylamine hydrochloride. Technical conditions];

- hydrogen peroxide [GOST 177-88. Hydrogen peroxide, hydrogen peroxide, perhydrol. Technical conditions];

- sodium hydroxide NaOH [GOST 2263-79. Technical caustic soda. 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 a 0.3 M 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 30 ° C for 10 min, then the mass is washed distilled water to remove unreacted reagents and by-products and treated with 500 ml of a 0.8 M solution of hydroxylamine hydrochloride (module 50) at pH 3 and room temperature for 40 min, then washed with distilled water again to remove excess hydroxylamine hydrochloride, then oxidize 150 ml of a 30% hydrogen peroxide solution (module 15) at pH 5.5 for 60 min, at room temperature, washed with distilled water and treated with NaOH at pH 8 for 5 min at room temperature, 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 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 0.333 mmol / L (the degree of extraction of 77.8%).

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 subjected to microwave irradiation with a power of 300 W at a frequency of 2.45 GHz and a temperature of 25 ° C for 15 minutes, then the mass is washed with distilled water to remove unreacted reagents and by-products and is treated with 150 ml of a 0.5 M solution of hydroxylamine hydrochloride (module 15) at pH 3.5 and room temperature for 1 h, then again washed with distilled water to remove excess hydroxylamine hydrochloride, then kislyayut 300 ml of a 30% solution of hydrogen peroxide (module 30) at pH 5 for 30 minutes at room temperature, washed with distilled water and treated with NaOH solution at pH 8 for 5 minutes at room temperature, washed with distilled water and dried.

The treated sorbent is poured into 1.5 L of an aqueous solution at room temperature (module 150) 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 0.3645 mmol / L (the degree of extraction of 75.7%).

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 55 ° C for 5 min, then the mass is washed distilled water to remove unreacted reagents and by-products and treated with 200 ml of a 0.6 M hydroxylamine hydrochloride solution (module 20) at pH 5 and room temperature for 50 minutes, then washed with distilled water again to remove excess hydroxylamine hydrochloride then oxidized with 400 ml of a 30% hydrogen peroxide solution (module 40) at pH 6 for 45 min, at room temperature, washed with distilled water and treated with a NaOH solution at pH 9 for 5 min at room temperature, washed with distilled water 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 0.387 mmol / L (recovery rate 74.2%).

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 4.5 and subjected to microwave irradiation with a power of 300 W at a frequency of 2.45 GHz and a temperature of 35 ° C for 5 min, then the mass is washed with distilled water to remove unreacted reagents and by-products and treated with 400 ml of a 1 M solution of hydroxylamine hydrochloride (module 40) at pH 3.5 and room temperature for 45 minutes, then again washed with distilled water to remove excess hydroxylamine hydrochloride, then islyayut 200 ml of a 30% solution of hydrogen peroxide (module 20) at pH 7 for 50 min at room temperature, washed with distilled water and treated with NaOH solution at pH 9 for 5 minutes at room temperature, washed with distilled water 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 0.4065 mmol / L (the degree of extraction of Cd (II) ions was 72.9%).

Example 5

10 g of wood sawdust is poured into 500 ml of a 0.25 M aqueous solution of sodium metaperiodate (module 50) 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 45 ° C for 10 min, then the mass is washed distilled water to remove unreacted reagents and by-products and treated with 300 ml of 0.3 M hydroxylamine hydrochloride solution (module 30) at pH 4.5 and room temperature for 55 minutes, then washed with distilled water again to remove excess hydroxylamine hydrochloride, thenoxidized with 500 ml of a 30% hydrogen peroxide solution (module 50) at pH 6.5 for 55 min, at room temperature, washed with distilled water and treated with NaOH at pH 9 for 5 min at room temperature, washed with distilled water and are 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 0.363; 0.3915; 0.402 and 0.426 mmol / L, respectively (degree of extraction of 75.8; 73.9; 73.2 and 71.6%).

The research results on the extraction of heavy metal ions from solutions in which the concentration of heavy metal ions is 1.5 mmol / l, according to the prototype and according to the claimed invention are presented in the table.

Thus, it follows from the data in the table 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 the time sorption (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. 77.8 - - - fifteen 2. - 75.7 - - one 3. - - 74,2 - 10 four. - - - 72.9 twenty 5. 75.8 73.9 73,2 71.6 twenty PROTOTYPE 68.1 - - - thirty 62,2 - - 45 - - 60.7 - 60 57.6 90 62.6 60.8 59.7 56.4 90

Claims (2)

1. A method of modifying cellulose-based sorbents designed to extract heavy metal ions from aqueous solutions by treating them with modifying agents, characterized in that the modification is carried out by sequentially treating them with solutions of an oxidizing agent, hydroxylamine hydrochloride, hydrogen peroxide and sodium hydroxide with water washing after each stage, and the interaction of sorbents with an oxidizing agent is carried out under microwave irradiation with a power of 300 W with a frequency of 2.45 GHz and a temperature of 25-55 ° C in 5-15 minutes in a solution with a concentration of 0.1-0.3 M at a pH of 2.5-4.5, and a solution / sorbent module of 15-50; treatment with hydroxylamine hydrochloride, it is carried out with a 0.3-1 M aqueous solution at pH 3-5, the solution / sorbent module 15-50, for 40-60 minutes at room temperature; Hydrogen peroxide oxidation is carried out with its 30% solution at pH 5-7 for 30-60 minutes at room temperature, the solution / sorbent module is 15-50, and treatment with sodium hydroxide solution is performed at pH 8-9 for 5 minutes at room temperature temperature, while contacting the modified sorbent is carried out for 1-20 minutes 2. The method according to claim 1, characterized in that sodium metaperiodate, iodic acid or sodium hypochlorite are used as an oxidizing agent, and cotton or wood pulp, short flax fiber or wood sawdust are used as sorbents.