The method of obtaining an ion-exchange fiber

 

(57) Abstract:

The invention relates to methods for ion exchange fibers based on polyacrylonitrile (PAN) and its copolymers and can be used in the extraction of metal ions Hg and Cr precise water from industrial complex salt composition. Get ion-exchange fiber processing (co)polyacrylonitrile fibers 8-13% solution polyethylenepolyamine and 0.2 to 0.3% sodium hydroxide solution in glycol at a temperature of 150-160oWith over 85-95 min at fixing fibrous tow. Fibers have high values of sorption capacity in relation to ions Hg+and Cr+while improving the strength characteristics of the resulting fiber. table 1.

The invention relates to methods for ion exchange fibers based on polyacrylonitrile (PAN) and its copolymers and can be used in the extraction of metal ions CR+6and Hg+1industrial wastewater treatment complex salt composition. Thus the physico-mechanical properties (strength and breaking elongation) of the obtained fibers allow it to be used in a flexible textile forms: fabric, ribbon, knitted fabric, Nykanen way of fibrous sorbent, obtained by treatment of PAN fibers di-, tri - polyamines containing ethylendiamine fragments and carboxyl group (SOYtotal5-7 mmol/g) and having a high basicity functional groups (B. C. Soldatov, G. I. Sergeev "Fibrous ion exchangers - a promising sorbents for separation of ions of heavy metals from aqueous solutions", GWHO, 1990, T. 35, 1, S. 101-106).

Closest to the present invention is a method of obtaining fibrous ion exchanger based on the PAN fibres (RF Patent 2101306 "Method of obtaining fibrous ion exchanger" MKI 6 C 08 J 5/20, publ. 10.01.98, bull. 1) processing 10-90% alkaline solution of alkylamine followed by treatment with an aqueous solution of dimethylaminoethanol.

The known method comprises the following steps:

1) treatment of PAN fibers (ternary copolymer) 10-80% solution of alkylamine (in particular, polyethylenepolyamine (Pepa) at 75-85oC for 30-60 min;

2) processing 10-30% solution dimethylamine at 75-85oC for 45-60 minutes At a concentration of probes 10% fibrous ion exchanger has the strength of 15.6 CN/Tex at sorption capacity at 0.1 G. of HCl equal to 5.4 mmol/g and IG+63 mmol/g (156 mg/g).

The best performance is achieved when using 70 is SOYCr+6reaches 3.8 mmol/g 200 mg/g), and the strength drops to 12.4 CN/Tex.

This method has the following disadvantages:

Process:

1) the two-phase process using two modifying agents, one of which (DMEM) is scarce raw materials;

2) duration (=150 min);

3) the use of aqueous media at elevated temperatures (destructive hydrolysis);

4) double rinse (water).

The result:

1) low physical-mechanical properties (up to 16 CN/Tex), sharply limiting the possibility of obtaining textile designs;

2) the ratio of acidic and basic groups, drastically reducing the selectivity of the ion exchanger (PL., example 13);

3) the ordinary values of sorption capacity (viviremos on ion CR+6(up to 150 mg/g fiber) and low capacity for Hg+(up to 300 mg/g);

4) a great loss of strength when working in cycles of sorption-desorption (up to 7 CN/Tex) in the regeneration of sulfuric acid.

The technical result of the claimed invention is to provide selectivity obtained with the sorbent in relation to ions of CR+6and Hg+that achieved by the optimal ratio of acid and bases the nom improving the strength characteristics of the resulting fiber due to the implementation of the modification process at temperatures support the processes of dehydrogenation and cyclization main chain polyacrylonitrile commit harness fiber length. Received strength characteristics of ion-exchange fibers provide an opportunity for textile processing sorbent in the filter materials of complex textures. An additional advantage of the proposed method is a simplification of the technological scheme (one stage) and reusable (up to 20 cycles) modifying the bath through the use of an anhydrous solvent.

This object is achieved in that in a method of producing ion-exchange fiber processing PAN-fibers of the probe by heating the processing of PAN fiber (and its copolymers) are fixed along the length of the fiber condition 8-12% th solutions of probes and 0.2-0.3% th solution of sodium hydroxide in glycols within 85-95 min at a temperature of 150-160oWith the ratio of basic and acidic groups in the fiber is implemented in a ratio of 5:1, and the strength properties are 22-26 CN/Tex.

Significant differences of the claimed invention are used in the process of high-boiling anhydrous solvents, lower concentrations of the modifying agentcy length throughout the modification process.

The invention is illustrated by the following examples:

Example 1. Fiber-based ternary copolymer of Acrylonitrile (Acrylonitrile, methyl methacrylate and taconova acid) in the form of a harness, fixed along the length of the fiber, treated with 10% of probes and 0.3% of sodium hydroxide in ethylene glycol for 90 min at a temperature of 150oWith, then the fiber is squeezed and washed with demineralized water until a neutral reaction by phenol red. Static volumetric capacity of amine groups (SOYNH) is 5,95 mmol/g of acidic groups (SOYCOOH)-1,20 mmol/g (ratio of amine groups to acid 5: 1), while the sorption capacity (CEHg) ion mercury is 1200 mg/g), CECr+6by Jonah CR+6312 mg/g, tensile strength 26 CN/Tex.

Example 2. Fiber-based ternary copolymer is treated according to the mode described in example 1, but in the solvent used glycerin. COENH= ceiling of 5.60 mmol/g, SOYCOOH= 1.12 mmol/g, CEHg=1000 mg/g), CECr+6=318 mg/g, tensile strength 25 CN/Tex.

Example 3. Fiber-based dual copolymer is treated according to the mode described in example 1, COENH=5.40 mmol/g, SOYCOOH=1,14 mmol/g, CHNg=1000 mg/g, Saut on mode, described in example 1, but in the solvent used glycerin, coenh= 5,52 mmol/g, SOYCOOH=1.12 mmol/g, CEHg=1000 mg/g), CECr+6=316 mg/g, a tensile strength of 25.8 CN/Tex.

Other examples of the preparation of ion-exchange fibers on the optimal mode in comparison with the performance of the prototype and analogue presented in the table.

The resulting fibers were studied using parameters of static exchange capacity in the main groups (SOYNH), acidic groups (SOYCOOH), sorption capacity for ions of CR+6and Hg+(CECr+6and CEHg+and bursting strength. All the above mentioned indicators were determined by the methods described in the literature: research Methods of ion-exchange resins., M, Chemistry, 1976, 208 S., authors Polanski N. G. , Gorbunov, Century, Polyanskaya N.I., Methods of physical-mechanical tests, chemical fibers, filaments and films., M., 1969, the authors Demina, N. In. and other

To assess the selectivity of the obtained sorbent studies, for example:

the fiber obtained by the optimal mode (example 1), were used in the selection of metal ions from aqueous solution composition: FeCl3- 5g/l, CaCl25 g/l, Hg2(NO3)25 g/l (weight of the fiber , is received by the mode (example 4), were used in the selection of metal ions from aqueous solution composition: FeCl35 g/l, CaCl25 g/l, K2Cr2O75 g/l (weight of fiber was 0.25 g in module 50), while CEFe+++- 18 mg/g, CECa++- 47 mg/g), CECr+6- 316 mg/g

From the experimental data shown in the table, it is seen that in comparison with the prototype of the claimed method the obtained fibrous ion exchanger with a ratio of the content of basic and acidic groups of 5:1 and strength characteristics 22-26 CN/Tex, which allows its use in the filter materials of different patterns. The prevailing (5 times) values COENHdefine high selectivity (selectivity) the resulting fiber when extracted from complex salt solutions of ions Hg+or Cr+6. Thus obtained fibers have a higher sorption capacity in relation to ions of Cr+6and Hg+(in the examples, the indicator CE). The ratio of ionic groups and high bursting strength caused a certain amount of the modifying agents acting on POLYACRYLONITRILE fiber under conditions that promote cyclization and formation of double bonds during ill operation of the filter media.

The method of obtaining an ion-exchange fiber processing polyacrylonitrile fiber solution polyethylenepolyamine when heated, characterized in that the processing of fixed length fiber spend 8-12% solution polyethylenepolyamine and 0.2 to 0.3% sodium hydroxide solution in glycol at 150-160oWith over 85-95 min prior to the implementation of the ratio of basic and acid groups in the resulting fiber, equal to 5: 1.

 

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