The method of obtaining chemisorptive carboxyl-containing fiber

 

(57) Abstract:

Usage: in the chemical industry as a fibrous ion-exchange materials. The inventive polyacrylonitrile fiber with 1.5 wt.% carboxyl groups treated with an aqueous solution containing 8-15 wt. % hydrazine and 1.0-2.0 wt.% sodium hydroxide, at 90-100oC for 120-150 minutes 1 table.

The invention relates to the production of ion-exchange fibers, and in particular to methods of obtaining chemisorptive carboxyl-containing fiber with a three-dimensional chemical net.

A method of obtaining an ion-exchange polyacrylonitrile fiber processing freshly formed fibers with a solution of sodium hydroxide and hydrazine sulfate [1]

There is a method allows to simplify and reduce the cost of obtaining fiber and increase its absorption capacity, however, the fiber has a relatively low strength characteristics.

A method of obtaining an ion-exchange fiber, using the processing of acrylic fiber in an aqueous solution of hydrazine hydrate is added and the sodium hydroxide solution [2]

There is a method allows to obtain fibers with high sorption capacity in the known way to obtain the ion-exchange polyacrylonitrile fibers by treatment of the fibers with a solution of a derivative of hydrazine and sodium hydroxide solution [3]

In this way the combination of processes of hydrazidine and alkaline hydrolysis in one technological stage reduces the duration of treatment, technological mode is easier than the previous method, but it requires a large consumption misusage and structuring of reagents (up to 120 g/l each). The total salt concentration of hydrazine and NaOH is about 24 wt. In addition, as a source of fiber in this case is used only svezhevorovanny not polyacrylonitrile fiber having a porous structure, which ensures penetration of hydrazine to the nitrile groups of the polyacrylonitrile, which promotes the formation of three-dimensional chemical grid. Dried (ready) polyacrylonitrile fiber such capacity does not have and therefore, when used as the initial standard Nitron fiber formation of three-dimensional grid is not happening.

A method of obtaining chemisorptive carboxyl-containing fiber processing polyacrylonitrile fibers containing at least 1.5 wt. carboxyl groups, an aqueous solution of hydrazine and sodium hydroxide at a temperature of 90oC [4] there is a method assests hemosorption carboxyl-containing fiber processing polyacrylonitrile fibers, containing not less than 1.5 wt. carboxyl groups, in an aqueous solution of hidroinstalime compounds and sodium hydroxide at an elevated temperature within 120-150 minutes [5] the Known method is selected as a prototype. The known method is the one, but has a significant consumption of reagents.

The present invention is the creation of a more efficient way to obtain chemisorptive polyacrylonitrile fiber-based copolymer containing in its structure at least 1.5 wt. monomer with carboxyl groups (based on acrylic fibre) with the required mechanical and sorption properties, reducing the consumption of reagents.

The technical result of the present invention is to simplify and cheapen the process of obtaining chemisorption of acrylic fiber with high strength characteristics.

This will allow the process of obtaining a chemisorptive fiber not only at the enterprises producing acrylic fiber, but also on any chemical production using industrial fiber Nitron.

This effect is achieved by one of the a group, aqueous solution of 8-15 wt. hydrazine and 1.0-2.0 wt. sodium hydroxide at a temperature of 90-100oC for 120-150 minutes

These processing modes polyacrylonitrile fiber (standard Nitron fiber) containing not less than 1.5 wt. monomer with carboxyl groups, ensure penetration of molecules of hydrazine to the nitrile groups of the original fiber and thereby create conditions for the formation of three-dimensional chemical grid. The presence of the three-dimensional structure, as is well known, prevents subsequently, as in the processing of fibers, and operating products, dissolution of the polymer in water and organic solvents.

By changing various process parameters (concentration of hydrazine and sodium hydroxide, temperature and reaction time) of the obtained experimental data, which are presented in the table.

Example 1. Polyacrylonitrile staple fiber Nitron loaded into a perforated basket reactor under irrigation softened water and mechanical seal.

Basket fiber installed in the reactor, chemical processing, close the lid and fill with a heated aqueous solution containing 13 wt. hydrazine and 1.5 wt. hydrox the EO pump heat exchanger reactor. Process temperature 95oC, a duration of 150 minutes

Upon completion of the reaction, the spent solution is poured into the container to strengthen and subsequent use.

The fiber in the reactor was washed with softened water in circulation. One rinsing for 15-20 minutes, room temperature, number of washes, 5-7.

The treated fiber is unloaded from the reactor and placed in the dryer. Drying temperature 80-90oC. the Fiber is dried to a moisture content of not more than 10 wt.

Physico-mechanical and sorption properties of the obtained carboxyl-containing fibers are shown in table (sample 3).

Example 2. The experience carried out as described in example 1, but instead reactor chemical processing using a centrifuge holds. The fiber is treated with a solution containing 15 wt. hydrazine and 1 wt. of sodium hydroxide. Process temperature 95oC, time of 150 minutes.

Washing and drying of the fibers is carried out at the modes mentioned in example 1.

Physico-mechanical and sorption properties of the obtained fiber are shown in table (sample 2).

The analysis is shown in table experimental data shows that obtaining the required characteristics is provided only pot at a temperature of 90-100oC.

When the concentration of hydrazine is higher than 15 wt. the fiber has a low COE (sample 1), while when the concentration of hydrazine below 8 wt. fibers with a low breaking strength (samples 4-6).

Increasing the reaction temperature above 100oC leads to a significant reduction of fiber (sample 10), and the temperature drops below the 90oC lowers the rate COE (sample 9).

Pretty much the same effect on the magnitude of bursting strength increase reaction time more than 150 minutes (sample 12), while reducing it below 120 minutes reduces COE (sample 11).

The data show that increasing the concentration of sodium hydroxide of more than 2 wt. results in chemisorption fiber with a low breaking strength (samples 6, 7), while the decrease in concentrations less than 1.0 wt. when the concentration of hydrazine 13% reduction in COE to 3.8 mgecw/g (sample 8).

From the above it is evident that the chemisorptive fiber obtained at a concentration of hydrazine 8-15 wt. the concentration of sodium hydroxide and 1.0-2.0 wt. and the reaction temperature 90-100oC for 120-150 minutes on physico-mechanical and sorption parameters satisfy the requirements is about, the increase in strength properties of the obtained fiber has a positive effect on the strength characteristics when producing non-woven materials, resulting in reduced waste during production and also has a positive effect on economic performance.

The method of obtaining chemisorptive carboxyl-containing fiber processing polyacrylonitrile fibers containing at least 1.5 wt. carboxyl groups, in an aqueous solution of hidroinstalime compounds and sodium hydroxide at an elevated temperature for 120 to 150 min, wherein the treatment is carried out with an aqueous solution containing 8 to 15 wt. hydrazine and 1.0 to 2.0 wt. sodium hydroxide at 90 100oC.

 

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Abstract // 2293061

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