Method of manufacturing ion-exchange polyacrylonitrile fiber (options)

FIELD: polymer materials.

SUBSTANCE: invention relates to manufacture of ion-exchange fibers with special properties, which can be used as sorbent or as a sorbent constituent for cleaning liquid media, largely natural and waste waters. Method consists in performing alkali hydrolysis of polyacrylonitrile fiber in presence of hydrazine at elevated temperature completed by treatment of fiber with active agent causing degradation of chromophore groups of fiber. Alternatively, ion-exchange fiber is manufactured via alkali hydrolysis of polyacrylonitrile fiber in presence of hydrazine at elevated temperature, hydrolysis reaction being effected in concentrated solution of salt of alkali metal with weak acid followed by treatment of fiber with active agent as above.

EFFECT: improved characteristics of fiber at lower consumption of reagents and stabilized manufacturing process to provide ion-exchange fiber with desired number of chelating sorption groups due to appropriate balance of acid and basic groups resulting from hydrolysis.

18 cl, 5 tbl, 16 ex

 

Group of inventions relates to the field of ion exchange fibers with special properties that can be used as a sorbent or as a component of the sorbent for cleaning fluids, mainly natural and waste waters.

Ion-exchange fibers based on polyacrylonitrile (PAN) fibers receive a variety of ways.

For the formation of carboxyl groups of the polyacrylonitrile and obtain a cation-exchange fibre based on it use the method of chemical transformations - saponification with alkali in the presence of a crosslinking agent. The absence of cross-linking agent can lead to the destruction of PAN fibers. For practical use as a cross-linking agent is recommended to use hydrazinobenzene connection, the effect of which significantly affect the swelling properties, the increase in exchange capacity and strength characteristics of the fiber. This method usually at an elevated temperature within 80-150 minutes.

Known in the prior art processes for the production of ion-exchange fibers, as described in the USSR №188617, MCI D 01 F 11/04, 1966; No. 586207, MCI D 01 F 11/04, 1978; p.p. of the Russian Federation No. 1051989, MCI D 01 F 11/04, 1995; No. 2044748, MKI C 08 J 5/22, 1995, book Fibers with special properties" edited by LaJolla, M.: Chemistry, 1980, p.78-79, have some disadvantages, such as multi-stage and, most of all, a great product is littelest process or/and a significant consumption of reagents, one of which (hydrazinoacetate connection) has a high toxicity. High consumption of reagents, respectively, leads to an appreciation of the process and solving problems related to wastewater treatment.

Simplification of the manufacturing process cationogenic fibers reach by single-stage processing of acrylic fiber.

Known single-stage method of processing involved in the processing of acrylic fiber in a bath prepared by mixing caustic soda concentration of 100-120 g/l and salts of hydrazine the same concentration in the ratio of 1:1 in the course of from 15 to 150 min at 95-100°S, the spin cycle, washing the fibers and then drying at 20-40°gives the opportunity to receive sorbent with high exchange capacity ("Fibers with special properties" edited by LaJolla, M.: Chemistry, 1980, s).

Known single-stage method of processing freshly formed of acrylic fiber with a solution containing 2.0 to 3.0% alkali sodium, 0.5 to 2.0% of hydrazine sulfate and 0.2 to 4.0% dimethylethyl-(butyl)-octadecylammonium or trimethylethylenediamine at a temperature of 96-98°With A.S. of the USSR №1032052, MCI D 01 F 11/04, 1983. Obtained by the method of ion-exchange fibers have high sorption properties with respect to the trace elements and high strength characteristics.

Known the Yong way of getting chemisorptive carboxyl-containing fiber processing polyacrylonitrile fibres with water solution, containing 8-15 wt.% hydrazine and 1.0-2.0 wt.% of sodium hydroxide. The processing of the fibers is carried out at a temperature of 90-100°for 120-150 minutes Then washed at room temperature for 15-20 minutes 5-7 times and dried at a temperature of 80-90°to a moisture content of not more than 10 wt.%.

These processing modes polyacrylonitrile fibers to obtain the ion-exchange fibers with high tensile strength - tensile strength fiber 13,5-16,3 CN/Tex and static exchange capacity of 5.5 to 5.8 mg·EQ/g and implement process using industrial fiber Nitron (patent No. 2102544, RF, MCI D 01 F 11/04, 1998 prototype).

Received above-described method, cation exchange fibers that bind metals by ion-exchange mechanism, have not sufficient capacity for selective sorption in the presence of background electrolyte. The use of large amounts of hydrazine can lead to a large residual hydrazine due to the fact that it is impossible to vary the ratio of acidic and basic groups.

It is known that polyacrylonitrile fibers modified with hydroxylamine acquire the ability to ion exchange and complexation. Processing polyacrylonitrile fibers conduct hydrochloric acid hydroxylamine in the presence of gidrolizuemye agent, as which the use of sodium carbonate. The bath temperature is 90°C. To increase the anion-exchange capacity of polyacrylonitrile fibers treated with hydroxylamine and improve hemosense anion-exchange fibers in the reaction mixture was added hydrazine ("Fibers with special properties" edited by LaJolla, M.: Chemistry, 1980, s-91).

Proposed method are the material that binds the metal cations on the pure mechanism of complex formation. Meanwhile, it is known that the greatest strength of binding heavy metals are complexes with compensated charge cations, when along with uncharged centers in complex includes anions. I.e. amphoteric ion-exchange fiber which is capable of selective adsorption regulated by the nature and proportions of groups, forming chelate complexes with metal ions.

With the purpose of obtaining such ion exchange fibers conduct the saponification polyacrylonitrile fibres solutions of sodium hydroxide in the presence of known salts of hydrazine and thiosemicarbazide ("Fibers with special properties" edited by LaJolla, M.: Chemistry, 1980, s). Total capacity of synthetic fibres-of polyampholytes reached 6,0-6,5 mg-EQ/g, and sorption capacity for carboxyl and amine groups was, respectively, of 3.0 to 4.5 and 3.0-2.0 mg-EQ/year These fibers have high sorbtion the th ability with respect to copper ions. When the pH of the solutions CuSO4from 2.8 to 4.0, they absorb 6,0-10,0 mg-equiv/g of copper ions within 5-10 minutes But in the process of cooking the obtained fiber, achieving high capacities, swell, turning into a gel-like mass, which further complicates the process of their processing.

The task of the claimed group of inventions and achievable technical result is to develop a new method of producing ion-exchange fibers based on polyacrylonitrile fiber, which provides qualitative characteristics of the fiber while reducing the consumption of reagents.

An additional objective is to achieve stability of the process and the receipt of ion-exchange fibers based on polyacrylonitrile fiber with a specified number of chelate sorption centers by varying the ratio of acidic and basic groups in the process of hydrolysis. Chelating ion-exchange centers in the material are formed by ion pairs core group acid group. When interacting pairs with ions of d-elements are formed stable complexes

2R'COO-...HN+R+Cu2+-->Cu(R COO)2(NR)2

where R' and R" are fragments of a polyacrylonitrile matrix. In an excess of acid groups on the core under the conditions of alkaline hydrolysis in an aqueous environment, the number of chelate sorption centers will be determined by the number of the ETS major groups.

The claimed group of inventions provides obtaining sufficiently pure, highly selective ion-exchange fibers which can selectively clean water from heavy metal ions, including, most importantly, drinking water.

This object is achieved by carrying out the alkaline hydrolysis of polyacrylonitrile fibers in the presence of hydrazine at elevated temperature with additional processing fiber active agent, accompanied by degradation of the chromophore groups of the fiber.

In the prior art it is known that the remains of hydrazine is removed from the fiber by thorough washing. Ion exchange of acrylic fiber obtained by the present method, used mainly for the treatment of drinking water, so for these fibers is not enough for one wash. Creates the need for removal of the fibers hydrazine derivatives, which potentially can be subjected to hydrolysis (for example, in the use of fibers) with the release of small amounts of hydrazine. Remove from the polymer matrix of residual hydrazine and/or its derivatives, which are attached to the matrix occurs due to ion exchange and/or covalent bonds. Loosely coupled hydrazine fixed to the matrix in groups

The accession of hydrazine in Melo the aqueous hydrolysis of the polyacrylonitrile leads to the formation of conjugated double bonds, with chronoformname properties, i.e. to the formation of chromophoric groups. In the process of destruction of hydrazide groups also destroyed the chain of conjugated double bonds, resulting in a lightening of the fibers.

According to the second variant of ion-exchange fibre is obtained by the alkaline hydrolysis of polyacrylonitrile fibers in the presence of hydrazine at elevated temperature, and the hydrolysis reaction is carried out in a concentrated salt solution of an alkali metal and a weak acid with subsequent processing of the fiber of the active agent, accompanied by degradation of the chromophore groups of the fiber. As a salt of an alkali metal and a weak acid using sodium carbonate, sodium acetate, potassium acetate or potassium carbonate. As an active agent in the first and second variants use a strong oxidising agent is hydrogen peroxide or calcium hypochlorite. Or as an active agent using water vapor and the treatment is carried out at elevated pressures. Additional processing can be performed in water microwave radiation.

The presence of the background electrolyte in the working solution limits the swelling of hydrolyzed POLYACRYLONITRILE fibers in such a way that its textile structure is retained even upon reaching the high exchange capacities. This allows to reduce the content of the crosslinking agent is a hydrazine - working of rest the re to quantities necessary to achieve the required exchange capacity of the main groups, and therefore the required capacity for chelating centers. In addition, the synthesis process can continue indefinitely without destroying the fiber. Thus, the content of unreacted hydrazine rinse can be significantly reduced. An additional factor in the stabilization process is the formation of the buffer alkali salt of a weak acid, which slows down the process of hydrolysis.

The task proved by the examples.

Example 1.

Hydrolysis of POLYACRYLONITRILE fibers was performed with a solution of the following composition: 2 g/l for N2H4; 4 g/l NaOH. Polyacrylonitrile fiber is treated with this solution at a temperature of 100°C for 60 min, the Ratio of the solution and the fiber was 1 l of a solution of 10 g of fiber. After hydrolysis of the fiber is washed to pH 7, squeezed and dried at a temperature of 80°C to constant weight. The material color is yellow - brown. Water draining from the material hydrazine is not specified - the material does not contain free hydrazine. Thus, molecules of hydrazine fixed in the matrix by covalent or ion-exchange relationships.

The following examples 2 and 3 describe the state of the material, the welded without additional processing stage. The material contains nathnac the high number of hydrazide groups which can be destroyed by the action of hydrochloric acid.

Example 2.

Hydrolysis of POLYACRYLONITRILE fibers was performed with a solution of the following composition: 2 g/l for N2H4; 4 g/l NaOH.

Polyacrylonitrile fiber is treated with this solution at a temperature of 100°C for 60 min, the Ratio of the solution and the fiber was 1 l of a solution of 10 g of fiber.

After hydrolysis of the fiber is washed to pH 7, squeezed and dried at a temperature of 80°C to constant weight. The material color is yellow - brown.

The method of determining the content of hydrolyzable derivatives of hydrazine below.

The washed sample was subjected to hydrolysis by the action of 1M HCl for 1 hour. During acid hydrolysis of hydrazide group in the material are destroyed, resulting in the solution enters the free hydrazine, the number of which can be judged on the content of gidrolizuyushchie hydrazide groups in the material. In the washings was determined by the content of hydrazine photometric method (wavelength 455 nm) in coloration of the reaction product of hydrazine with paradimethylaminobenzaldehyde. The analysis of the content of hydrolyzable hydrazide groups was 300 µg/g of material.

Example 3.

Material received and processed according to example 2, was subjected to secondary exposure to HCl. The amount of hydrazine, washed away when you re guide is Alise, amounted to less than 10 μg/g Example 3 confirms the accuracy of the determination gidrolizuyushchie hydrazide groups according to the method described in example 2.

Example 4.

A sample of the material obtained according to example 2, after washing subjected vozdeistviy of water vapor by increased pressure in the autoclave. The steam pressure in the autoclave was 2 ATM, the processing time is 20 minutes.

The material after processing has a white color.

Content gidrolizuyushchie hydrazide groups defined in example 2 was less than 10 μg/g

Example 5.

A sample of the material obtained according to example 2, after washing was subjected to heating in a microwave oven (microwave processing). The sample was kept in distilled water in an open tank. The processing time from the moment of boiling water was 5 minutes.

The material after processing has a light yellow color. Content gidrolizuyushchie hydrazide groups defined in example 2 was less than 10 μg/g

Example 6.

A sample of the material obtained according to example 2, was treated with 10% hydrogen peroxide solution. The amount of hydrogen peroxide was 30 mg per 1 g of the material, the processing time is 1 hour.

The material after processing has a light yellow color. Content gidrolizuyushchie hydrazide groups defined according to example 2, was 25 mcg/g

Example 7.

The material sample, extracting the aqueous according to example 2, treated with a 10% solution of calcium hypochlorite. The amount of calcium hypochlorite was 50 mg per 1 g of the material, the processing time is 1 hour.

The material after processing has a light yellow color. Content gidrolizuyushchie hydrazide groups defined in example 2 was 15 mcg/g

Example 8.

Hydrolysis of POLYACRYLONITRILE fibers was performed with a solution of the following composition: 100 g/l2CO3; 0.2 g/l for N2H4; 4 g/l NaOH.

Polyacrylonitrile fiber is treated with this solution at a temperature of 100°C for 60 min, the Ratio of the solution and the fiber was 1 l of a solution of 10 g of fiber. Thus, hydrazine contained in the reaction mixture in the amount of 0.625 mmol per 1 g of the original fiber.

After hydrolysis of the fiber is washed to pH 7, is treated with hydrogen peroxide according to example 6, squeezed and dried at a temperature of 80°C to constant weight.

Example 9.

Hydrolysis of POLYACRYLONITRILE fibers was performed with a solution of the following composition: 100 g/l in Na2CO3; 0.4 g/l in N2H4; 4 g/l NaOH.

Polyacrylonitrile fiber is treated with this solution at a temperature of 100°C for 60 min, the Ratio of the solution and the fiber was 1 l of a solution of 10 g of fiber. Thus, hydrazine contained in the reaction mixture in the amount of 1.25 mmol per 1 g of the original fiber.

After conclusion of the Oia hydrolysis of the fiber is washed to pH 7, treated with hydrogen peroxide according to example 6, squeezed and dried at a temperature of 80°C to constant weight.

Example 10.

Hydrolysis of POLYACRYLONITRILE fibers was performed with a solution of the following composition: 100 g/l in Na2CO3; 0.6 g/l in N2H4; 4 g/l NaOH.

Polyacrylonitrile fiber is treated with this solution at a temperature of 100°C for 60 min, the Ratio of the solution and the fiber was 1 l of a solution of 10 g of fiber. Thus, hydrazine contained in the reaction mixture in the amount of 1.875 mmol per 1 g of the original fiber.

After hydrolysis of the fiber is washed to pH 7, is treated with hydrogen peroxide according to example 6, squeezed and dried at a temperature of 80°C to constant weight.

Example 11.

Hydrolysis of POLYACRYLONITRILE fibers was performed with a solution of the following composition: 100 g/l in Na2CO3; 0.4 g/l in N2H4; 2 g/l NaOH.

Polyacrylonitrile fiber is treated with this solution at a temperature of 100°C for 60 min, the Ratio of the solution and the fiber was 1 l of a solution of 10 g of fiber. Thus, hydrazine contained in the reaction mixture in the amount of 1.25 mmol per 1 g of the original fiber.

After hydrolysis of the fiber is washed to pH 7, is treated with hydrogen peroxide according to example 6, squeezed and dried at a temperature of 80°C to constant weight.

Example 12.

Hydro is of the PAN fibres was performed with a solution of the following composition: 100 g/l CH 3COONa (sodium acetate); 0.2 g/l for N2H4; 4 g/l NaOH.

Polyacrylonitrile fiber is treated with this solution at a temperature of 100°C for 60 min, the Ratio of the solution and the fiber was 1 l of a solution of 10 g of fiber. Thus, hydrazine contained in the reaction mixture in the amount of 1.25 mmol per 1 g of the original fiber.

After hydrolysis of the fiber is washed to pH 7, is treated with hydrogen peroxide according to example 6, squeezed and dried at a temperature of 80°C to constant weight.

Data on the properties of ion-exchange fibers obtained by the present method, are shown in table 1

Example 13.

Sorption column with a diameter of 30 mm and a height of 70 mm was filled with the obtained in example 2 amphoteric ion exchange fibers based on polyacrylonitrile fibres. The number of fibers in the column was 10, Through the column passed 10 l model solution containing copper in an amount of 5 mg/l, with a speed of 50 ml/min In each liter of the filtrate was determined by the content of copper. The results of the analysis are presented in table 2.

Example 14. The experiment was carried out according to example 13, but was used as a model solution containing salts of copper (5 mg/l) and calcium as background electrolyte (40 mg/l). The results are shown in table 3.

Example 15.

Used sorption column according to Example 13. H the RES column missed the model solution, containing 0.500 mg/l of lead in the form of nitrate. In each liter of the filtrate was determined by the content of lead. The results of the analysis are presented in table 4.

Example 16. The experiment was carried out according to example 13, but was used as a model solution containing lead salt (0.500 mg/l) and calcium as background electrolyte (40 mg/l). The results are shown in table 5.

Table 1.

Capacitive properties of ion-exchange fibers obtained by the described method.
NN sampleThe exchange capacity of carboxyl groups, mEq/gExchange capacity of the main groups, mEq/gFull exchange capacity, mEq/gSelective exchange capacity of copper, mEq/g
80.64.34.90.58
91.14.15.21.05
101.74.05.71.72
111.22.53.71.20
121.04.25.20.96

Table 2.

The effectiveness of the sight of the TCI model solution sorption column, containing amphoteric material.
The number of missed the model solution, lCopper concentration in filtrate, mg/l% removal of copper
1<0.05>99.0
2<0.05>99.0
3<0.05>99.0
4<0.05>99.0
5<0.05>99.0
6<0.05>99.0
70.0599.0
80.0599.0
90.0698.8
100.1098.0

Table 3.

The cleaning efficiency model solution sorption column containing amphoteric material.
The number of missed the model solution, lCopper concentration in filtrate, mg/l% removal of copper
1<0.05>99.0
2<0.05>99.0
3<0.05>99.0
4<0.05> 99.0
5<0.05>99.0
60.0599.0
70.0599.0
80.0599.0
90.0898.4
100.1297.6

Table 4.

The cleaning efficiency model solution sorption column containing amphoteric material.
The number of missed the model solution, lLead concentration in the filtrate, mg/l% removal of lead
10.005>99.0
20.005>99.0
30.005>99.0
40.005>99.0
50.005>99.0
60.005>99.0
70.005>99.0
80.005>99.0
90.005>99/0
100.00599.0

Table 5.

The cleaning efficiency model solution Sorbonne column containing amphoteric material.
The number of missed the model solution, lLead concentration in the filtrate, mg/l% removal of lead
1<0.005>99.0
2<0.005>99.0
3<0.005>99.0
4<0.005>99.0
5>0.005>99.0
6<0.005>99.0
7<0.005>99.0
80.00599.0
90.00599/0
100.00698.8

1. The method of obtaining an ion-exchange fiber alkaline hydrolysis of polyacrylonitrile fibers in the presence of hydrazine at elevated temperature, characterized in that it further spend processing fiber active agent, accompanied by degradation of the chromophore groups of the fiber.

2. The method according to claim 1, characterized in that as an active agent using strong oxidizing agent.

3. The method according to claim 2, characterized in that as a strong okoli the El use hydrogen peroxide.

4. The method according to claim 2, characterized in that as a strong oxidant use calcium hypochlorite.

5. The method according to claim 1, characterized in that as an active agent using water vapor and the treatment is carried out at elevated pressure.

6. The method according to claim 1, characterized in that the treatment is carried out in water by microwave radiation.

7. The method according to claim 1, characterized in that the alkaline hydrolysis is carried out at a temperature of 80-110°C.

8. The method according to claim 1, characterized in that the alkaline hydrolysis is carried out in a period of 60-120 minutes

9. The method of obtaining an ion-exchange fiber alkaline hydrolysis of polyacrylonitrile fibers in the presence of hydrazine at elevated temperature, characterized in that the hydrolysis reaction is carried out in a concentrated salt solution of an alkali metal and a weak acid with subsequent processing of the fiber of the active agent, accompanied by degradation of the chromophore groups of the fiber.

10. The method according to claim 9, characterized in that as the salt of an alkali metal and a weak acid using sodium carbonate.

11. The method according to claim 9, characterized in that as the salt of an alkali metal and a weak acid using sodium acetate.

12. The method according to claim 9, characterized in that as an active agent using strong oxidizing agent.

13. The method according to item 12, characterized in that as a strong oxidant used is form hydrogen peroxide.

14. The method according to item 12, characterized in that as a strong oxidant use calcium hypochlorite.

15. The method according to claim 9, characterized in that as an active agent using water vapor and the treatment is carried out at elevated pressure.

16 the Method according to claim 9, characterized in that the treatment is carried out in water by microwave radiation.

17. The method according to claim 9, characterized in that the alkaline hydrolysis is carried out at a temperature of 80-110°C.

18. The method according to claim 9, characterized in that the alkaline hydrolysis is carried out in a period of 60-120 minutes



 

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