Preparation method of porous adsorption material for sewage treatment

Abstract

The present invention relates to the technical field of sewage treatment, and discloses a preparation method of a porous adsorption material for sewage treatment. In the present invention, modified polyacrylonitrile and polyethylene oxide are mixed and spun by a wet spinning machine to obtain a porous adsorption material for sewage treatment. The polyacrylonitrile fiber porous adsorption material of the present invention contains a large number of hydrophilic groups such as carboxyl groups and phenolic hydroxyl groups, which improves the hydrophilicity of the polyacrylonitrile fiber, has higher dispersibility and liquid absorption in water, is conducive to increasing the adsorption sites. At the same time, the carboxyl group, mercapto group and o-hydroxy Schiff base structure have strong coordination and complexation adsorption properties for these metal ions, significantly improving the adsorption capacity and adsorption performance of polyacrylonitrile fiber for metal ions, and having good practical applications in the treatment of metal-containing sewage and wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically to a preparation method of a porous adsorption material for sewage treatment. Background Art

[0002] Polyacrylonitrile fiber has good heat resistance, strong solvent resistance and corrosion resistance, and high mechanical strength, and is widely used in fields such as separation membranes and nanofiltration membranes. Modifying polyacrylonitrile fiber to improve its adsorption performance for metal ions can expand its practical application in sewage and wastewater treatment. Currently, methods for modifying polyacrylonitrile and its fibers include copolymerization modification, grafting modification, hydrolysis modification, etc.

[0003] Introducing functional groups into polyacrylonitrile fiber can improve its adsorption performance. Chinese Patent Application CN118437291A discloses a tertiary amine-modified polyacrylonitrile fiber and its preparation method and application. The raw material of polyacrylonitrile fiber is modified, which has a larger specific surface area and hydrophilicity, and can be used in fields such as adsorption of dye wastewater and adsorption of heavy metal ion wastewater. Compared with this invention, the present invention introduces carboxyl, mercapto, and o-hydroxy Schiff base structures into the polyacrylonitrile porous fiber matrix, aiming to improve the adsorption capacity of polyacrylonitrile fiber for metal ions. Summary of the Invention

[0004] The present invention solves the problem of poor adsorption performance of polyacrylonitrile fiber for metal ion pollutants.

[0005] The technical solution of the present invention is: a preparation method of a porous adsorption material for sewage treatment:

[0006] Step A: Add dimethyl sulfoxide, acrylonitrile, and allyl functional monomer to a reaction vessel, stir and then dropwise add azobisisobutyronitrile. After the polymerization reaction, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain modified polyacrylonitrile.

[0007] Step B: Add N,N-dimethylacetamide, modified polyacrylonitrile, and polyethylene oxide to a container, heat and stir to dissolve, perform vacuum degassing, then spin through a wet spinning machine, use an N,N-dimethylacetamide aqueous solution with a volume fraction of 35-40% as the coagulation bath, then perform stretching in a hot water bath, and finally soak in hot water and dry to obtain a porous adsorption material for sewage treatment.

[0008] Further, in step A, the dosage of acrylonitrile is 100 parts by weight, the allyl functional monomer is 3-10 parts by weight, and azobisisobutyronitrile is 1-1.1 parts by weight.

[0009] Further, in step A, the temperature of the polymerization reaction is 60-70 °C, and the reaction time is 18-24 h.

[0010] Further, in step B, the dosage of the modified polyacrylonitrile is 100 parts by weight, and that of the polyethylene oxide is 10 - 13 parts by weight.

[0011] Further, in step B, the N,N - dimethylacetamide aqueous solution.

[0012] Further, the preparation method of the allyl functional monomer is as follows:

[0013] Step (1): Add a solvent, 100 parts by weight of 2 - hydroxy - 5 - chloromethylbenzaldehyde, 42 - 50 parts by weight of N - allylmethylamine, and 60 - 72 parts by weight of triethylamine into a reaction vessel, react at 25 - 40 °C for 18 - 30 h, remove the solvent by rotary evaporation, wash with water, and recrystallize the product in ethanol to obtain an intermediate.

[0014] Step (2): Add ethanol, 59 - 63 parts by weight of cysteine, and 20 - 22 parts by weight of potassium hydroxide into a reaction vessel, stir and then add 100 parts by weight of the intermediate, react at 40 - 65 °C for 4 - 8 h, cool and dropwise add hydrochloric acid solution to adjust the pH to 5 - 6, precipitate a solid, filter, and recrystallize the product in dichloromethane to obtain the allyl functional monomer. The reaction formula is:

[0015]

[0016] Further, in step (1), the solvent is dichloromethane, ethanol or tetrahydrofuran.

[0017] The technical effect of the present invention: The present invention uses 2 - hydroxy - 5 - chloromethylbenzaldehyde, N - allylmethylamine, and cysteine as reactants to prepare an allyl functional monomer, then copolymerizes it with acrylonitrile to obtain a modified polyacrylonitrile containing carboxyl, mercapto, and o - hydroxy Schiff base structures, and finally uses polyethylene oxide as a pore - forming agent to obtain a porous polyacrylonitrile fiber adsorption material through wet spinning.

[0018] The polyacrylonitrile fiber porous adsorption material of the present invention contains a large number of hydrophilic groups such as carboxyl and phenolic hydroxyl groups, which improves the hydrophilicity of the polyacrylonitrile fiber, has higher dispersibility and liquid absorption in water, is beneficial to increasing adsorption sites. At the same time, the carboxyl, mercapto, and o - hydroxy Schiff base structures have strong coordination and complexation adsorption properties for these metal ions, significantly improving the adsorption capacity and adsorption performance of the polyacrylonitrile fiber for metal ions, and having good practical applications in the treatment of metal - containing sewage and wastewater. Specific embodiments

[0019] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to related embodiments. The preferred embodiments of the present invention are given in the embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0020] Example 1:

[0021] Step (1): Add 60 mL of dichloromethane, 5 g of 2-hydroxy-5-chloromethylbenzaldehyde, 2.1 g of N-allylmethylamine, and 3 g of triethylamine into a reaction vessel, react at 30 °C for 24 h, remove the solvent by rotary evaporation, wash with water, and recrystallize the product in ethanol to obtain an intermediate.

[0022] Step (2): Add 200 mL of ethanol, 3.78 g of cysteine, and 1.32 g of potassium hydroxide into a reaction vessel, stir and then add 6 g of the intermediate, react at 50 °C for 6 h, cool and dropwise add hydrochloric acid solution to adjust the pH to 6, precipitate a solid, filter, and recrystallize the product in dichloromethane to obtain an allyl functional monomer.

[0023] Step (3): Add 400 mL of dimethyl sulfoxide, 80 g of acrylonitrile, and 2.4 g of the allyl functional monomer into a reaction vessel, stir and then dropwise add 0.8 g of azobisisobutyronitrile, heat up to 65 °C, carry out a polymerization reaction for 18 h, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain modified polyacrylonitrile.

[0024] Step (4): Add 500 mL of N,N-dimethylacetamide, 100 g of modified polyacrylonitrile, and 10 g of polyethylene oxide into a container, heat to 70 °C, stir to dissolve, carry out vacuum degassing, and then spin through a wet spinning machine. Use an aqueous solution of N,N-dimethylacetamide with a volume fraction of 35% as a coagulation bath, then carry out stretching in a hot water bath at 95 °C, and finally soak in hot water at 60 °C for 7 days, and dry to obtain a porous adsorption material for sewage treatment.

[0025] Example 2:

[0026] Step (1): Add 70 mL of ethanol, 5 g of 2-hydroxy-5-chloromethylbenzaldehyde, 2.1 g of N-allylmethylamine, and 3.4 g of triethylamine into a reaction vessel, react at 40 °C for 18 h, remove the solvent by rotary evaporation, wash with water, and recrystallize the product in ethanol to obtain an intermediate.

[0027] Step (2): Add 150 mL of ethanol, 3.54 g of cysteine, and 1.2 g of potassium hydroxide into the reaction vessel. After stirring, add 6 g of the intermediate, react at 65 °C for 4 h, with condensation reflux during the reaction. Cool and add hydrochloric acid solution dropwise to adjust the pH to 5, precipitate, filter, and recrystallize the product in dichloromethane to obtain the allyl functional monomer.

[0028] Step (3): Add 500 mL of dimethyl sulfoxide, 80 g of acrylonitrile, and 5.4 g of the allyl functional monomer into the reaction vessel. After stirring, add 0.85 g of azobisisobutyronitrile dropwise, heat up to 70 °C, carry out the polymerization reaction for 18 h, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain the modified polyacrylonitrile.

[0029] Step (4): Add 600 mL of N,N-dimethylacetamide, 100 g of the modified polyacrylonitrile, and 13 g of polyethylene oxide into the container, heat to 70 °C, stir to dissolve, carry out vacuum degassing, then spin through a wet spinning machine, use an aqueous solution of N,N-dimethylacetamide with a volume fraction of 40% as the coagulation bath, then carry out stretching in a hot water bath at 95 °C, and finally soak in hot water at 70 °C for 7 days, and dry to obtain the porous adsorption material for sewage treatment.

[0030] Example 3:

[0031] Step (1): Add 70 mL of tetrahydrofuran, 5 g of 2-hydroxy-5-chloromethylbenzaldehyde, 2.5 g of N-allylmethylamine, and 3.6 g of triethylamine into the reaction vessel, react at 25 °C for 30 h, remove the solvent by rotary evaporation, wash with water, and recrystallize the product in ethanol to obtain the intermediate.

[0032] Step (2): Add 150 mL of ethanol, 3.62 g of cysteine, and 1.2 g of potassium hydroxide into the reaction vessel. After stirring, add 6 g of the intermediate, react at 40 °C for 8 h, cool and add hydrochloric acid solution dropwise to adjust the pH to 5, precipitate, filter, and recrystallize the product in dichloromethane to obtain the allyl functional monomer.

[0033] Step (3): Add 500 mL of dimethyl sulfoxide, 80 g of acrylonitrile, and 8 g of the allyl functional monomer into the reaction vessel. After stirring, add 0.88 g of azobisisobutyronitrile dropwise, heat up to 60 °C, carry out the polymerization reaction for 24 h, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain the modified polyacrylonitrile.

[0034] Step (4): Add 600 mL of N,N-dimethylacetamide, 100 g of modified polyacrylonitrile, and 12 g of polyethylene oxide into a container, heat to 70 °C, stir to dissolve, perform vacuum degassing, then carry out spinning through a wet spinning machine, use an aqueous solution of N,N-dimethylacetamide with a volume fraction of 35% as the coagulation bath, then perform stretching in a hot water bath at 95 °C, and finally soak in hot water at 65 °C for 7 days, and dry to obtain a porous adsorption material for sewage treatment.

[0035] Comparative Example 1:

[0036] Step (1): Add 400 mL of dimethyl sulfoxide and 80 g of acrylonitrile into a reaction container, stir and then dropwise add 0.8 g of azobisisobutyronitrile, raise the temperature to 65 °C, carry out a polymerization reaction for 18 h, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain polyacrylonitrile.

[0037] Step (2): Add 500 mL of N,N-dimethylacetamide, 100 g of polyacrylonitrile, and 10 g of polyethylene oxide into a container, heat to 70 °C, stir to dissolve, perform vacuum degassing, then carry out spinning through a wet spinning machine, use an aqueous solution of N,N-dimethylacetamide with a volume fraction of 35% as the coagulation bath, then perform stretching in a hot water bath at 95 °C, and finally soak in hot water at 60 °C for 7 days, and dry to obtain a porous adsorption material for sewage treatment.

[0038] Comparative Example 2:

[0039] Step (1): Add 400 mL of dimethyl sulfoxide, 80 g of acrylonitrile, and 2.4 g of intermediate (prepared in the same way as in Example 1) into a reaction container, stir and then dropwise add 0.8 g of azobisisobutyronitrile, raise the temperature to 65 °C, carry out a polymerization reaction for 18 h, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain modified polyacrylonitrile.

[0040] Step (2): Add 500 mL of N,N-dimethylacetamide, 100 g of modified polyacrylonitrile, and 10 g of polyethylene oxide into a container, heat to 70 °C, stir to dissolve, perform vacuum degassing, then carry out spinning through a wet spinning machine, use an aqueous solution of N,N-dimethylacetamide with a volume fraction of 35% as the coagulation bath, then perform stretching in a hot water bath at 95 °C, and finally soak in hot water at 60 °C for 7 days, and dry to obtain a porous adsorption material for sewage treatment.

[0041] Comparative Example 3:

[0042] Step (1): Add 60 mL of dichloromethane and 4.53 g of 4-(chloromethyl)benzaldehyde (the structural formula is )、2.1 g of N-allylmethylamine and 3 g of triethylamine were reacted at 30 °C for 24 h. The solvent was removed by rotary evaporation, washed with water, and the product was recrystallized from ethanol to obtain intermediate A with the structural formula

[0043] Step (2): 200 mL of ethanol, 3.78 g of cysteine, and 1.32 g of potassium hydroxide were added to the reaction vessel. After stirring, 5.53 g of intermediate A was added, and the reaction was carried out at 50 °C for 6 h. After cooling, the pH was adjusted to 6 by dropwise addition of hydrochloric acid solution, and a precipitate was formed. After filtration, the product was recrystallized from dichloromethane to obtain allyl-functional monomer A with the structural formula

[0044] Step (3): 400 mL of dimethyl sulfoxide, 80 g of acrylonitrile, and 2.4 g of allyl-functional monomer A were added to the reaction vessel. After stirring, 0.8 g of azobisisobutyronitrile was added dropwise, and the temperature was raised to 65 °C for a polymerization reaction for 18 h. After cooling, water was added for precipitation. After filtration, it was washed with ethanol and hot water and dried to obtain modified polyacrylonitrile.

[0045] Step (4): 500 mL of N,N-dimethylacetamide, 100 g of modified polyacrylonitrile, and 10 g of polyethylene oxide were added to the container, heated to 70 °C, stirred and dissolved, and degassed under vacuum. Then, spinning was carried out through a wet spinning machine, using an aqueous solution of N,N-dimethylacetamide with a volume fraction of 35% as the coagulation bath, followed by stretching in a hot water bath at 95 °C, and finally immersed in hot water at 60 °C for 7 days and dried to obtain a porous adsorption material for sewage treatment.

[0046] Prepare 500 mL of a lead ion Pb 2+ standard solution, add 30 - 60 mg of the porous adsorption material for sewage treatment, stir and adsorb at 25 °C for 3 h, take the supernatant, and measure the concentration of the solution by atomic absorption spectrophotometer to calculate the adsorption capacity W. W = (C0 - C) × V / m. C0 is the initial concentration of the solution, C is the concentration of the solution after adsorption, V is the volume of the solution, and m is the mass of the porous adsorption material.

[0047] Table 1

[0048]

[0049] Prepare 500 mL of a copper ion Cu 2+ standard solution, add 30 - 60 mg of the porous adsorption material for sewage treatment, stir and adsorb at 25 °C for 2 h, take the supernatant, and measure the concentration of the solution by atomic absorption spectrophotometer to calculate the adsorption capacity W. W = (C0 - C) × V / m. C0 is the initial concentration of the solution, C is the concentration of the solution after adsorption, V is the volume of the solution, and m is the mass of the porous adsorption material.

[0050] Table 2

[0051]

[0052] Prepare 500 mL of cadmium ion Cd 2+ standard solution with a concentration of 60 mg / L, add 20 - 40 mg of porous adsorption material for sewage treatment, stir and adsorb at 25 °C for 3 h, take the supernatant, test the concentration of the solution by atomic absorption spectrophotometer, and calculate the adsorption capacity W. W = (C0 - C) × V / m. C0 is the initial concentration of the solution, C is the concentration of the solution after adsorption, V is the volume of the solution, and m is the mass of the porous adsorption material.

[0053] Table 3

[0054]

[0055]

[0056] As can be seen from the above table, compared with Comparative Example 1, the polyacrylonitrile fiber porous adsorption materials of Examples 1 - 3 have high adsorption capacities for Pb 2+ , Cu 2 + , Cd 2+ respectively. This is mainly because the polyacrylonitrile fiber contains a large number of hydrophilic groups such as carboxyl groups and phenolic hydroxyl groups, which improve the hydrophilicity of the polyacrylonitrile fiber, resulting in higher dispersibility and liquid absorption in water, facilitating the increase of adsorption sites. At the same time, the carboxyl group, mercapto group and o-hydroxy Schiff base structure have strong coordination and complexation adsorption properties for these metal ions, significantly improving the adsorption capacity and adsorption performance of the polyacrylonitrile fiber for metal ions.

[0057] In Comparative Example 2, the polyacrylonitrile fiber porous adsorption material obtained by copolymerizing the intermediate with acrylonitrile monomer does not contain carboxyl group, mercapto group and o-hydroxy Schiff base structure, resulting in lower coordination and complexation adsorption properties for metal ions and poor adsorption capacity and adsorption performance.

[0058] In Comparative Example 3, the polyacrylonitrile fiber porous adsorption material obtained by copolymerizing allyl functional monomer A with acrylonitrile monomer does not contain o-hydroxy Schiff base structure, and its coordination and complexation adsorption properties for metal ions are lower than those of each example, resulting in poor adsorption capacity and adsorption performance.

[0059] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a porous adsorption material for sewage treatment, characterized in that, The preparation method includes the following steps: Step A: Add dimethyl sulfoxide, acrylonitrile, and allyl functional monomer into a reaction vessel. After stirring, add azobisisobutyronitrile dropwise. After the polymerization reaction, cool, add water for precipitation, filter, wash, and dry to obtain modified polyacrylonitrile; The structural formula of the allyl functional monomer is Step B: Add N,N-dimethylacetamide, modified polyacrylonitrile, and polyethylene oxide into a container, heat and stir to dissolve, perform vacuum degassing, then spin the solution through a wet spinning machine. Use an N,N-dimethylacetamide aqueous solution as the coagulation bath, then perform stretching in a hot water bath, and finally soak in hot water and dry to obtain a porous adsorption material for sewage treatment; The preparation method of the allyl functional monomer is as follows: Step (1): Add a solvent, 2-hydroxy-5-chloromethylbenzaldehyde, N-allylmethylamine, and triethylamine into a reaction vessel, react at 25 - 40 °C for 18 - 30 h, remove the solvent by rotary evaporation, wash, and recrystallize to obtain an intermediate; Step (2): Add ethanol, cysteine, and potassium hydroxide into a reaction vessel, stir and then add the intermediate, react at 40 - 65 °C for 4 - 8 h, cool and add a hydrochloric acid solution to adjust the pH to 5 - 6, precipitate, filter, and recrystallize the product to obtain the allyl functional monomer; In the said Step (1), the dosage of 2-hydroxy-5-chloromethylbenzaldehyde is 100 parts by weight, N-allylmethylamine is 42 - 50 parts by weight, and triethylamine is 60 - 72 parts by weight; In the said Step (2), the dosage of cysteine is 59 - 63 parts by weight, potassium hydroxide is 20 - 22 parts by weight, and the intermediate is 100 parts by weight.

2. The preparation method of the porous adsorption material for sewage treatment according to claim 1, characterized in that, In the said Step A, the dosage of acrylonitrile is 100 parts by weight, the allyl functional monomer is 3 - 10 parts by weight, and azobisisobutyronitrile is 1 - 1.1 parts by weight.

3. The preparation method of the porous adsorption material for sewage treatment according to claim 1, characterized in that, In the said Step (1), the solvent is dichloromethane, ethanol, or tetrahydrofuran.

4. The preparation method of the porous adsorption material for sewage treatment according to claim 1, wherein, In the said Step A, the temperature of the polymerization reaction is 60 - 70 °C, and the reaction time is 18 - 24 h.

5. The preparation method of the porous adsorption material for sewage treatment according to claim 1, characterized in that, In the said Step B, the dosage of modified polyacrylonitrile is 100 parts by weight, and polyethylene oxide is 10 - 13 parts by weight.

6. The preparation method of the porous adsorption material for sewage treatment according to claim 1, characterized in that, In the said Step B, the volume fraction of the N,N-dimethylacetamide aqueous solution is 35 - 40%.

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