RU2351548C1 - Method for extraction of heavy metal ions from aqueous solutions - Google Patents

Abstract

FIELD: sewage treatment facilities.

SUBSTANCE: invention is related to methods for extraction of heavy metal ions by sorption on cellulose-containing sorbates from solutions of different nature - aqueous, water-organic, and may be used in development of technologies for utilisation of heavy metal ions from sewage. Method for extraction of heavy metal ions includes contact of purified aqueous solutions with cellulose-containing sorbates that represent secondary offals of agricultural complex, which are modified by active chlorine-triazine dyes. Sorbates are previously treated in solution of NaOH with concentration of 0.2-2 g/l for 5-30 minutes at room temperature. Sorbates modification is done for 10-30 s in aqueous solution of the following composition, g/l: dichlorine-triazine dye (active Bright-Red 5 CX) - 5-20; sodium bicarbonate - 2-20; carbamide - 10-40 at module solution/sorbate of 10-20. Then sorbates are squeezed and dried, flushed by hot water and soaked for 10-30 s in solution of poly-2-hydroxypropylene-(1-N,N-dimethyl ammonia chloride) with concentration of 10-40 g/l, squeezed and dried. Contact is realised for 10-20 minutes at the module of 50-200.

EFFECT: invention provides for reduction of time required for preliminary treatment of sorbates, performance of modification in single stage at reduction of total time required for extraction of heavy metal ions from 120 to 10-20 minutes.

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Description

FIELD OF TECHNOLOGY

The invention relates to methods for the extraction of heavy metal ions by sorption on cellulose-containing sorbents from solutions of various nature (aqueous and aqueous-organic) resulting from various technological processes in the food, textile and chemical industries, and can be used to improve membrane and sorption technologies, in the development of technologies for the disposal of heavy metal ions from aqueous solutions and wastewater.

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 B01J 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; 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. N 12. 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 for extracting copper ions from aqueous solutions of its salts using natural cellulosic materials: cotton fiber (CB), bamboo cellulose (BC), jute fiber (DW) and wood sawdust ( DO) stained with monochlorotriazine active dyes: C.I. Active Red 31, C.I. Active Orange 13, C.I. Active Yellow 18 and C.I. Active Blue 25 [3. Shukla S.R., Sakhardande V.D. Cupric ion removal by dyed cellulosic materials // J. Appl. Polym. Sci. - 1990. - V. 41. - No. 11-12. - P. 2655-2663]. Sorbents were prepared as follows: cotton and jute fiber were purified by boiling for 4 hours in a solution containing soap and soda, after which they were washed with excess water and dried in air. The bamboo mass and sawdust were crushed to approximately the same size, washed thoroughly with excess water and dried in air. The process of staining the substrates included the following operations: the dye powder was diluted to the state of paste with cold water and diluted with hot water at a temperature of 70 ° C. The substrate was placed in a dyeing bath at a temperature of 60 ° C and a module 50, prepared to obtain a 1% color. After processing the material for 10 minutes, 70 g / l of Glauber's salt was added and dyeing was continued at 80 ° C for another 20 minutes. Then 15 g / L trisodium phosphate was added, after which dyeing was carried out for another 30 minutes. After dyeing, the substrate was removed from the bath, squeezed, washed thoroughly with water, treated with soap in the presence of 2 g / L nonionic surfactant during boiling, washed again with water and dried in air. The extraction of copper ions was carried out by placing weighed samples of a substrate weighing 1 g in 50 ml of an aqueous solution of copper salt with a concentration of 250 mg / L and kept at a constant temperature for 2 hours. Then, the substrate was filtered through a porous glass filter, and the filtrate was analyzed for the content of the metal salt remaining after adsorption of the substrate.

As a result of the use of such sorbents stained in accordance with the prototype method, the degree of extraction of copper ions reached 72.5–97.6%, increasing in the series CV <LW <BC <DO.

The disadvantages of the prototype are:

- long (up to 4 hours) pre-treatment time of sorbents;

- long-term (1 h) multi-stage sorbent dyeing procedure;

- high temperature dyeing (60-80 ° C);

- long sorption time (2 h);

- the use of colored sorbent for the extraction of copper ions from concentrated solutions (250 mg / l), resulting in a maximum degree of purification of 97.6% of the residual concentration of metal ions in the solution is 6 mg / l; therefore, this method should be used in conjunction with the fine method.

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:

- reduce the time of preliminary processing of sorbents;

- carry out the modification of sorbents in one stage, while dramatically reducing the process time;

- carry out the modification at room temperature;

- reduce the time of extraction of metal ions;

- clean diluted solutions of salts of heavy metals to achieve low (less than 1 mg / l) residual concentrations of metal ions in solution;

- maintain a high degree of extraction of metal ions.

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 cellulose-containing sorbents, which are secondary products of agro-industrial complex processing, modified active chlorotriazine dyes, and the sorbents are pre-treated in a NaOH solution with a concentration of 0.2-2 g / l for 5-30 min at room temperature, the modification of sorbents is carried out for 10-30 s in an aqueous solution, followed by composition, g / l: dichlorotriazine dye active Bright Red 5 CX - 5-20; sodium bicarbonate - 2-20; urea - 10-40 with a solution / sorbent module 10-20 at room temperature, after completion of the modification, the sorbents are squeezed out, dried, washed with hot water and kept in a solution of poly-2-hydroxypropylene- (1-N, N -dimethylammonium chloride) with a concentration of 10-40 g / l at room temperature, squeeze and dry, and contacting is carried out for 10-20 minutes with a module of 50-200.

Sawdust from pine wood is a secondary product of the woodworking industry of the following composition,%: cellulose (53.8), lignin (26.9 ... 28.2), hemicellulose (20.5), pentosans (10.7-11.2) , mannan (7.1), galactan (1.5), extractive substances (1.0 ... 4.1), minerals (0.2 ... 0.23) [Nikitin N.I. Chemistry of wood and cellulose. - M.-L .: Ed. USSR Academy of Sciences, 1962.712 s].

Cotton waste (short fiber - fluff) is a by-product of primary processing of cotton of the following composition,%: cellulose (94), protein substances (1.3), ash substances (1.2), pectin substances (0.9), organic acids (0.8), waxy substances (0.6), sugars (0.3), others (0.9).

Short flax fiber is a secondary product of processing the flax industry of the following composition,%: cellulose (73.9 ... 78.8), lignin (2.1 ... 2.9), protein substances (2.1 ... 2.3), waxy substances (1.7 ... 2.9), pectin substances (1.9 ... 2.3), ash substances (0.7 ... 1.1), others (12.8 ... 15.4) [Krichevsky G.E. et al. Chemical technology of textile materials: Textbook for universities / G.E. Krichevsky, M.V. Korchagin, A.V. Senakhov. - M., 1985. - 640 p.].

As components of the solution used in the coloring of sorbents, use:

- sodium bicarbonate [GOST 4201-79. Sodium carbonate. Technical conditions];

urea [GOST6691-77. Urea. Specifications.];

- poly-2-hydroxypropylene- (1-N, N-dimethylammonium chloride) [TU 2227-222-00203312-02] - a quaternary polyamine - a polymer based on epichlorohydrin and dimethylamine. The molecular weight is from 10 ⁴ to 10 ⁶ . It is an aqueous solution in the form of a viscous, colorless to yellow liquid, uniform in consistency and without impurities. Miscible with water in any proportions. Stable at pH 1-14. Mass fraction of the main substance - not less than 47%, viscosity at 20 ° С - in the range of 20-95 cps, pH 4-7, density at 20 ° С - 1.13-1.18 g / cm ³ , pour point - not more than 10 ° C.

Chemical formula

Active bright red dye 5СХ.

Chemical formula

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

Example 1

Short flax fiber is pretreated in an aqueous solution of NaOH with a concentration of 0.2 g / l for 30 min at room temperature and dried. 10 g of short flaxseed fiber is poured into 100 ml of an aqueous solution (module 10) at room temperature, containing, g / l: dichlorotriazine dye active Bright Red 5 CX - 5; sodium bicarbonate - 2; urea - 10 and stand for 30 s, after completion of the modification, the sorbent is squeezed out, dried for 3 minutes at 100 ° C, washed with hot water and kept in a solution of poly-2-hydroxypropylene- (1-N, N-dimethylammonium chloride) for 10 s concentration of 40 g / l at room temperature, squeeze and dry for 3 minutes at 130 ° C.

The modified sorbent is poured into 0.5 l of an aqueous solution at room temperature (module 50) containing 10 mg / l of copper ions. After 10 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 0.19 mg / L (recovery 98.1%).

Example 2

Sawdust is pre-treated in an aqueous solution of NaOH with a concentration of 1 g / l for 10 min at room temperature and dried. 10 g of wood sawdust is poured into 150 ml of an aqueous solution (module 15) at room temperature, containing, g / l: dichlorotriazine dye active Bright Red 5 CX - 10; sodium bicarbonate - 10; urea for 20 seconds and kept for 15 seconds, after completion of the modification, the sorbent is squeezed out, dried for 4 minutes at 110 ° С, washed with hot water and kept for 15 seconds in a solution of poly-2-hydroxypropylene- (1-N, N-dimethylammonium chloride) with a concentration 20 g / l at room temperature, squeeze and dry for 3.5 minutes at 120 ° C.

The modified sorbent is poured into 1 l of an aqueous solution at room temperature (module 100) containing 10 mg / l of zinc ions. After 15 minutes, the solution was filtered and the content of Zn (II) ions was determined in the filtrate. The concentration of zinc ions after three sorption cycles was 0.43 mg / L (95.7% recovery).

Example 3

Cotton waste is pretreated in an aqueous NaOH solution with a concentration of 2 g / l for 5 min at room temperature and dried. 10 g of sorbent is poured into 200 ml of an aqueous solution (module 20) at room temperature, containing, g / l: active dichlorotriazine dye Brightly -Red 5 CX - 20; sodium bicarbonate - 20; urea is 40 and stand for 10 s, after completion of the modification, the sorbent is squeezed out, dried for 5 minutes at 120 ° C, washed with hot water and kept in a solution of poly-2-hydroxypropylene- (1-N, N-dimethylammonium chloride) for 30 s concentration of 10 g / l at room temperature, squeeze and dry for 4 minutes at 125 ° C.

A modified sorbent is poured into 2 L of an aqueous solution at room temperature (module 200) containing 10 mg / 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 after three cycles of sorption was 0.65 mg / L (93.5% recovery).

The results of the experiments 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 extract heavy metal ions by sorption from aqueous solutions, while reducing the time of preliminary processing of sorbents from 4 hours to 5-30 minutes; carry out the process of modifying sorbents in one stage, while drastically (from 60 minutes to 10-30 s) reduce the process time; carry out modification at room temperature; reduce the time of extraction of metal ions from 120 to 10-20 min; remove heavy metal ions from dilute solutions to achieve low residual concentrations of metal ions in the solution.

P
R
AND
M
E
R
S Sorbent Active dye τ _arr min τ _cr , s τ _sorb min C _p , mg / l T _cr , ° C The degree of extraction,% Cu ²⁺ Zn ²⁺ Cd ²⁺ one Klv Bright Red 5 CX thirty 10 10 0.65 twenty 98.1 - - 2 BEFORE Also 10 fifteen fifteen 0.43 twenty 95.7 3 XB Also 5 twenty twenty 0.19 twenty - - 93.5 P
R
ABOUT
T
ABOUT
T
AND
P XB Orange 13 240 3600 120 68.75 60-80 72.5 - - BEFORE Red 31 5 3600 120 6 60-80 97.6 - - Far East Yellow 18 240 3600 120 34.75 60-80 86.1 - - Note. DO - sawdust; KLV - short flax fiber; XO - cotton waste, HV - cotton fiber, BC - bamboo cellulose, DV - jute fiber; τ _arr , τ _cr , τ _sorbc - processing time, dyeing and sorption; With _p - the residual concentration of ions in solution.

Claims (1)

The method of extraction of heavy metal ions from aqueous solutions by contacting them at room temperature with cellulose-containing sorbents, which are secondary products of agro-industrial complex processing, modified active chlorotriazine dyes, characterized in that the sorbents are pre-treated in a NaOH solution with a concentration of 0.2-2 g / l for 5-30 minutes at room temperature, the modification of the sorbents is carried out for 10-30 s in an aqueous solution of the following composition, g / l: dichlorotria zine dye active bright red 5 CX 5-20; sodium bicarbonate 2-20; urea 10-40 with a solution / sorbent module 10-20 at room temperature, after completion of the modification, the sorbents are squeezed out, dried, washed with hot water and kept in a solution of poly-2-hydroxypropylene- (1-N, N- dimethylammonium chloride) with a concentration of 10-40 g / l at room temperature, squeeze and dry, and contacting is carried out for 10-20 minutes with a module of 50-200.