A functional fibre material of amidoxime and a method for preparing the same

Abstract

The present application relates to a kind of amidoxime functional fiber material and its preparation method, belong to functional polymer material technical field.The functional fiber material is formed by the amide bond of the carboxyl group in part or all of polyacrylonitrile carboxylic fiber material and the amidoxime group in polyamidoxime compound, polyamidoxime is grafted to polyacrylonitrile carboxylic fiber, and the functional fiber material is obtained;The carboxyl group in the polyacrylonitrile carboxylic fiber material is 0.5mmol / g~2.0mmol / g.The surface of the functional fiber material is not rolled up, form is good, matrix mechanical property is not lost, and adsorption rate is fast.Compared with prior art, under the condition of same amidoxime group content or theoretically same amidoxime group content, the mechanical strength of the functional fiber material of the present application is better.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of amidoxime functional fiber materials and its preparation method, belong to functional polymer material technical field. BACKGROUND

[0002] Amidoxime polyacrylonitrile fiber material is a kind of amidoxime fiber material, it has excellent chelating performance to heavy metal ions, noble metal ions and uranyl root ions, is widely used in seawater uranium extraction, valuable metal extraction and wastewater treatment etc.

[0003] But the existing amidoxime polyacrylonitrile fiber material is that nitrile group in polyacrylonitrile fiber is directly converted into amidoxime group, its surface is crimped, form is poor, texture is brittle and hard, so it will affect the adsorption performance of fiber material, its mechanical property is poor, which is not conducive to practical engineering application. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a kind of amidoxime functional fiber materials and its preparation method, the surface of the functional fiber material is not crimped, form is good, matrix mechanical property is not lost, adsorption rate is fast.Compared with prior art, under the condition of same amidoxime group content or theoretically same amidoxime group content, the mechanical strength of the functional fiber material of the present application is better.

[0005] To achieve the purpose of the present application, the following technical solutions are provided.

[0006] An amidoxime functional fiber material, the amidoxime functional fiber material is formed by the amide bond of part or all carboxyl in polyacrylonitrile carboxylic fiber material and amidoxime group in polyamidoxime compound through amidation reaction, polyamidoxime is grafted onto polyacrylonitrile carboxylic fiber to obtain the functional fiber material;The amount of carboxyl in the polyacrylonitrile carboxylic fiber material is 0.5mmol / g-2.0mmol / g, that is, 0.5mmol-2.0mmol of carboxyl is contained in per gram of polyacrylonitrile carboxylic fiber material.

[0007] A preparation method of the amidoxime functional fiber material as described in the present application, the method steps are as follows:

[0008] (1) hydroxylamine hydrochloride is added to polyacrylonitrile (PAN) solution to obtain a mixed solution;The pH value of the mixed solution is adjusted to 7-8, then heated at 50-100 DEG C, after hydroxylamine hydrochloride is completely reacted, polyamidoxime compound (PAO) solution is obtained;

[0009] The molar ratio of nitrile group in the PAN solution to hydroxylamine hydrochloride is (1-20): 1;

[0010] The average molecular weight of PAN in the PAN solution is 1000-30000, and the mass fraction of PAN is 0.1%-5%; the PAN solution can be obtained by polymerization of acrylic acid in a laboratory, or can be a PAN solution obtained by dissolving PAN powder in a solvent, wherein the solvent is a solvent commonly used in the art which can dissolve PAN powder;

[0011] (2) mixing the polyacrylonitrile carboxylic fiber material with the PAO solution according to a mass ratio of 1:(10-100), stirring and reacting at 60-100°C for 0.5-6h, taking out the fiber material after reaction, washing and drying to obtain the amidoxime functional fiber material;

[0012] The form of the polyacrylonitrile carboxylic fiber material is a conventional selection in the art, such as fiber tows, cloth, felt or film, etc.

[0013] Preferably, a weakly basic substance is used to adjust the pH value of the mixed solution, and the weakly basic substance is sodium carbonate or sodium bicarbonate.

[0014] Preferably, the particle size of PAN as a solute in the PAN solution is greater than 0 and less than or equal to 100nm.

[0015] Preferably, the solvent of the PAN solution is water, or a mixture of one or more of dimethylformamide, dimethyl sulfoxide, sulfolane and ethylene nitrite with water.

[0016] Preferably, in step (1), heating at 50-100°C for 0.5-6h, and then using ferric ions to determine whether hydroxylamine hydrochloride still exists in the mixed solution after reaction; if hydroxylamine hydrochloride exists, continue to react until hydroxylamine hydrochloride is completely reacted, i.e. there is no hydroxylamine hydrochloride in the mixed solution after reaction; if there is no hydroxylamine hydrochloride in the mixed solution after heating at 50-100°C for 0.5-6h, then proceed to the subsequent reaction.

[0017] The polyacrylonitrile carboxylic fiber material can be obtained by one of the following three methods:

[0018] I. polyacrylonitrile carboxylic fiber material obtained by hydrolysis of polyacrylonitrile fiber;

[0019] II. polyacrylonitrile carboxylic fiber material obtained by polymerization and spinning of acrylonitrile with acrylic acid or itaconic acid;

[0020] III. polyacrylonitrile carboxylic fiber material obtained by polymerization and spinning of acrylonitrile with the corresponding monomers required for use, and then hydrolysis of the fiber containing nitrile groups.

[0021] Advantages

[0022] 1. The present application provides a kind of amidoxime functional fiber material, the functional fiber material is obtained by the amidation reaction of part or all carboxyl in polyacrylonitrile carboxylic fiber material and amidoxime group in polyamidoxime compound, polyamidoxime is grafted onto polyacrylonitrile carboxylic fiber by amide bond, and then the functional fiber material is obtained, i.e. a kind of functional fiber material (PAN-PAO functional fiber material) grafted with polyamidoxime based on polyacrylonitrile carboxylic fiber, which has no surface crimping, good morphology, the mechanical properties of matrix are not lost, and the adsorption rate is fast. Compared with the prior art, the mechanical strength of the functional fiber material is better under the same amidoxime group content or the same theoretical amidoxime group content.

[0023] 2. The present application provides a kind of preparation method of amidoxime functional fiber material, the method first synthesizes polyamidoxime compound (PAO) solution, then the amidation reaction of amine group in PAO solution and carboxyl in polyacrylonitrile carboxylic fiber is carried out to complete grafting, and the functional fiber material of the present application is obtained. The method can prepare the functional fiber material, i.e. the PAN-PAO functional fiber material, by two-step heating reaction, which has the characteristics of simplicity and convenience.

[0024] 3. The present application provides a kind of preparation method of amidoxime functional fiber material, the particle size of PAN as solute in the PAN solution is 100 nm or less, which promotes its dissolution in solvent and is conducive to the reaction. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is the reaction mechanism diagram for preparing PAO solution in the method step (1) of the present application.

[0026] Figure 2 It is the reaction mechanism diagram for preparing PAN-PAO functional fiber material in the method step (2) of the present application. DETAILED DESCRIPTION

[0027] The present application is further described below in combination with drawings and specific embodiments, wherein the method is a conventional method unless otherwise specified, and the raw materials can be obtained from public commercial channels or prepared according to literature unless otherwise specified.

[0028] The mechanism explanation of the preparation method of the functional fiber material of the present application is as follows:

[0029] In the method, the reaction mechanism of step (1) is as shown in Figure 1 The nitrile group in polyacrylonitrile in PAN solution reacts with hydroxylamine hydrochloride under the condition of pH value of 7-8 to form amidoxime group, and PAO solution is obtained.

[0030] The reaction mechanism of step (2) is asFigure 2 As shown, the polyacrylonitrile carboxylic fiber tows contain carboxyl groups, and the carboxyl groups react with amine groups in the PAO solution under heating conditions, realizing grafting of polyamidoxime (PAO) on the polyacrylonitrile fiber matrix, so that the functional fiber material, i.e., the PAN-PAO functional fiber material, is obtained.

[0031] In the following examples:

[0032] Ferrous ions are used to determine whether hydroxylamine hydrochloride still exists in the mixed solution after the reaction, and the specific method is as follows: 10 mL of the solution after the reaction is added dropwise into 5 mL of a ferric chloride solution; the mass fraction of ferric chloride in the ferric chloride solution is 0.2%; after dropwise addition, if the ferric chloride solution turns light green, it indicates that the mixed solution after the reaction still contains hydroxylamine hydrochloride, because hydroxylamine hydrochloride can reduce trivalent iron ions to divalent iron ions, so the ferric chloride solution turns light green; if the ferric chloride solution does not change color, it indicates that the mixed solution after the reaction does not contain hydroxylamine hydrochloride, i.e., the hydroxylamine hydrochloride has completely reacted.

[0033] Example 1

[0034] A preparation method of an amidoxime functional fiber material, the steps of which are as follows:

[0035] (1) 0.5 g of PAN powder with an average molecular weight of 2000 is dissolved in 100 mL of deionized water to obtain a polyacrylonitrile (PAN) solution, wherein the particle size of the PAN powder is less than or equal to 100 nm; then 0.1 g of hydroxylamine hydrochloride is added to the PAN solution to obtain a mixed solution, the molar ratio of nitrile groups in the PAN solution to hydroxylamine hydrochloride is 10:1, the pH value of the mixed solution is adjusted to 7.5 with sodium carbonate, and then the mixed solution is heated at a temperature of 80°C for 1 h, and then it is determined whether hydroxylamine hydrochloride still exists in the mixed solution after the reaction; in this example, after heating at a temperature of 80°C for 1 h, the solution after the reaction does not contain hydroxylamine hydrochloride, indicating that the hydroxylamine hydrochloride has completely reacted, and a polyamidoxime compound (PAO) solution is obtained.

[0036] (2) The polyacrylonitrile carboxylic fiber tows with a dry weight of 0.5 g are immersed into the PAO solution, wherein the amount of carboxyl groups in the polyacrylonitrile carboxylic fiber tows is 1.8 mmol / g, and the mass ratio of the polyacrylonitrile carboxylic fiber tows to the PAO solution is 1:50; the reaction is heated at a temperature of 70°C for 1 h with stirring, and then the polyacrylonitrile carboxylic fiber tows after the reaction are taken out, washed with deionized water, and dried to obtain the functional fiber material, i.e., the PAN-PAO functional fiber material. The surface of the prepared PAN-PAO functional fiber material is not rolled up, which means that the contact area is larger and the adsorption rate is faster when the functional groups are adsorbed. Meanwhile, the amidoxime groups are obtained by grafting through matrix reaction, and the breaking strength of the matrix fiber is not only not lost, but is further enhanced.

[0037] Example 2

[0038] A preparation method of an amidoxime functional fiber material, the steps of which are as follows:

[0039] (1) A PAN solution obtained by polymerization of acrylic acid in a laboratory is used, wherein the average molecular weight of the PAN is 5000, and the mass fraction is 2%, 1.5 g of hydroxylamine hydrochloride is added to 100 mL of the PAN solution to obtain a mixed solution, the molar ratio of nitrile groups in the PAN solution to hydroxylamine hydrochloride is 2:1, sodium carbonate is used to adjust the pH value of the mixed solution to 7, and then the mixed solution is heated at a temperature of 70°C for 2 h, and then it is determined whether hydroxylamine hydrochloride still exists in the mixed solution after the reaction; in this example, the solution after the reaction does not contain hydroxylamine hydrochloride after being heated at a temperature of 70°C for 2 h, which indicates that the hydroxylamine hydrochloride has completely reacted, and a polyamidoxime compound (PAO) solution is obtained;

[0040] (2) Different from step (2) of Example 1, the mass ratio of the polyacrylonitrile carboxylic fiber tows to the PAO solution prepared in step (1) is 1:40, and the rest of the operations are the same as those in step (2) of Example 1, to obtain the functional fiber material, i.e., the PAN-PAO functional fiber material. The surface of the prepared PAN-PAO functional fiber material is not rolled up, which means that the contact area is larger and the adsorption rate is faster when the functional groups are adsorbed. Meanwhile, the amidoxime groups are obtained by grafting through matrix reaction, and the breaking strength of the matrix fiber is not only not lost, but is further enhanced.

[0041] Comparative Example 1

[0042] Polyacrylonitrile fibers are directly modified by using a hydroxylamine hydrochloride solution, specifically as follows:

[0043] (1) 0.1 g of hydroxylamine hydrochloride and 0.1 g of sodium carbonate are configured into an aqueous solution of 100 mL;

[0044] (2) The polyacrylonitrile fiber tows with a dry weight of 0.5 g were added to the aqueous solution, and heated at 80°C for 1 h. The reacted fiber was taken out, washed with deionized water, and dried at 35°C to obtain the amidoxime-functionalized polyacrylonitrile fiber obtained by the direct modification method.

[0045] Test Example 1

[0046] The polyacrylonitrile carboxylic acid fiber tows used in step (2) of Example 1, the PAN-PAO functional fiber material prepared in Example 1, and the PAN-PAO functional fiber material prepared in Example 2 were tested as follows:

[0047] The polyacrylonitrile carboxylic acid fiber tows, the PAN-PAO functional fiber material prepared in Example 1, and the PAN-PAO functional fiber material prepared in Example 2, each with a dry weight of 0.5 g, were respectively placed in a 50 mL copper sulfate solution with a copper sulfate concentration of 500 mg / L, and shaken at room temperature for 5 min to allow the three fiber materials to absorb copper ions. After shaking, the three fiber materials were taken out, and the copper ion concentration in the adsorbed copper sulfate solution was measured using a flame atomic absorption spectrophotometer. The measurement results are as follows:

[0048] The copper ion concentration in the copper sulfate solution after adsorption by the polyacrylonitrile carboxylic acid fiber tows was 480 mg / L, indicating that the adsorption amount of copper ions by the polyacrylonitrile carboxylic acid fiber tows was 2 g / kg after 5 min of absorption.

[0049] The copper ion concentration in the copper sulfate solution after adsorption by the PAN-PAO functional fiber material prepared in Example 1 was 212 mg / L, indicating that the adsorption amount of copper ions by the PAN-PAO functional fiber material was 28.8 g / kg after 5 min of absorption.

[0050] The copper ion concentration in the copper sulfate solution after adsorption by the PAN-PAO functional fiber material prepared in Example 2 was 105 mg / L, indicating that the adsorption amount of copper ions by the PAN-PAO functional fiber material was 39.5 g / kg after 5 min of absorption.

[0051] According to the reaction mechanism of the present application and the above test results, it is shown that the functional fiber material, i.e. a PAN-PAO functional fiber material, is prepared in Examples 1-2, and the PAN-PAO functional fiber material has a good adsorption effect on metal ions.

[0052] Test Example 2

[0053] The breaking strength of the polyacrylonitrile carboxylic fiber tows as the matrix in Examples 1-2, the PAN-PAO functional fiber materials prepared in Examples 1-2, and the amidoxime-modified polyacrylonitrile fiber prepared in Comparative Example 1 by the direct modification method were tested by using a fiber strength tester, and the test results are as follows:

[0054] The breaking strength of the polyacrylonitrile carboxylic fiber tows as the matrix in Examples 1-2 was 9.87 cN;

[0055] The breaking strength of the PAN-PAO functional fiber material prepared in Example 1 was 10.13 cN;

[0056] The breaking strength of the PAN-PAO functional fiber material prepared in Example 2 was 10.22 cN;

[0057] The breaking strength of the amidoxime-modified polyacrylonitrile fiber prepared in Comparative Example 1 by the direct modification method was 7.90 cN.

[0058] According to the test results, the breaking strength of the PAN-PAO functional fiber materials prepared in Examples 1-2 is higher than that of the polyacrylonitrile carboxylic fiber tows as the matrix and the amidoxime-modified polyacrylonitrile fiber prepared in Comparative Example 1. Further, 0.5 g of PAN powder was dissolved in 100 mL of deionized water to obtain a PAN solution and reacted with 0.1 g of hydroxylamine hydrochloride in Example 1, and 0.5 g of polyacrylonitrile fiber tows was reacted with 0.1 g of hydroxylamine hydrochloride in Comparative Example 1, and the amount of hydroxylamine hydrochloride used in the two reactions is the same. In theory, the amount of amidoxime groups produced in the two reactions is the same, so the amount of amidoxime groups produced in the two reactions is not much different in the actual reaction. Under the condition that the amount of amidoxime groups is basically the same, the mechanical strength of the PAN-PAO functional fiber material prepared in Example 1 is higher than that of Comparative Example 1. Therefore, it can be seen that, compared with the direct modification method, the PAN-PAO functional fiber material prepared by the method of the present application has better mechanical strength under the same amount of amidoxime groups or the same amount of amidoxime groups in theory.

[0059] The present application includes but is not limited to the above examples, any equivalent replacement or partial improvement made under the principle of the present application shall be considered within the protection scope of the present application.

Claims

1. A functional fibre material of the amidoxime type, characterised in that: The functional fiber material is obtained by grafting poly-amidoxime onto polyacrylonitrile carboxylic fiber through amide bonds formed between part or all of carboxyl groups in the polyacrylonitrile carboxylic fiber material and amidoxime groups in the poly-amidoxime compound; the amount of carboxyl groups in the polyacrylonitrile carboxylic fiber material is 0.5 mmol / g to 2.0 mmol / g.

2. A process for the preparation of the functional amidoxime fibre material as claimed in claim 1, characterized in that: The method comprises the following steps: (1) adding hydroxylamine hydrochloride into a PAN solution to obtain a mixed solution; adjusting the pH value of the mixed solution to 7 to 8, and then heating and reacting at 50 to 100 DEG C until the hydroxylamine hydrochloride is completely reacted to obtain a PAO solution; The molar ratio of nitrile groups in the PAN solution to hydroxylamine hydrochloride is (1 to 20) : 1; The average molecular weight of PAN in the PAN solution is 1000 to 30000, and the mass fraction of the PAN is 0.1% to 5%; (2) mixing the polyacrylonitrile carboxylic fiber material with the PAO solution according to a mass ratio of 1 : (10 to 100), stirring and reacting at 60 to 100 DEG C for 0.5 to 6 hours, taking out the fiber material after the reaction, and washing and drying to obtain the functional fiber material.

3. A process for the preparation of a functional amidoxime fibre material according to claim 2, characterized in that: The pH value of the mixed solution is adjusted by using an alkaline substance, and the alkaline substance is sodium carbonate or sodium bicarbonate.

4. A process for the preparation of a functional amidoxime fibre material according to claim 2 or 3, characterized in that: The particle size of the PAN as a solute in the PAN solution is greater than 0 and less than or equal to 100 nm.

5. A process for the preparation of a functional amidoxime fibre material according to claim 4, characterized in that: The solvent of the PAN solution is water, or a mixture of one or more of dimethylformamide, dimethyl sulfoxide, sulfolane and ethylene nitrate and water.

6. A process for the preparation of a functional amidoxime fibre material according to claim 5, characterized in that: In step (1), the heating and reaction is performed at 50 to 100 DEG C for 0.5 to 6 hours, and then ferric ion is used to determine whether there is hydroxylamine hydrochloride in the mixed solution after the reaction; if there is hydroxylamine hydrochloride, the reaction is continued until the hydroxylamine hydrochloride is completely reacted, i.e. there is no hydroxylamine hydrochloride in the mixed solution after the reaction; if there is no hydroxylamine hydrochloride in the mixed solution after the heating and reaction at 50 to 100 DEG C for 0.5 to 6 hours, the subsequent reaction is performed.

Images