Preparation method of porous adsorption material for sewage treatment

Abstract

The invention relates to the technical field of sewage treatment, and discloses a preparation method of a porous adsorption material for sewage treatment, which comprises the following steps: mixing modified polyacrylonitrile and polyoxyethylene, and spinning by a wet spinning machine to obtain the porous adsorption material for sewage treatment. The polyacrylonitrile fiber porous adsorption material contains a large number of hydrophilic groups such as carboxyl groups and phenolic hydroxyl groups, the hydrophilicity of polyacrylonitrile fibers is improved, the dispersity and liquid absorbency in water are higher, adsorption sites are increased, meanwhile, the carboxyl groups, the sulfydryl groups and the o-hydroxyl Schiff base structures have a good adsorption effect, and the adsorption efficiency is improved. The prepared polyacrylonitrile fiber has strong coordination and complexing adsorption performance on the metal ions, the adsorption capacity and adsorption performance of the polyacrylonitrile fiber metal ions are remarkably improved, and the polyacrylonitrile fiber has good practical application in treatment of metal-containing wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, in particular to a method for preparing 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. It is widely used in separation membranes, nanofiltration membranes and other fields. Modifying polyacrylonitrile fiber and improving its adsorption performance for metal ions can expand its practical application in sewage and wastewater treatment. At present, the modification methods of polyacrylonitrile and its fibers include copolymerization modification, grafting modification, hydrolysis modification and other methods.

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

[0004] The invention solves the problem that the polyacrylonitrile fiber has poor adsorption performance on metal ion pollutants.

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

[0006] Step A, add dimethyl sulfoxide, acrylonitrile and allyl functional monomer into a reaction container, add azobisisobutyronitrile dropwise after stirring, cool after polymerization, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain modified polyacrylonitrile.

[0007] Step B, adding N, N-dimethylacetamide, modified polyacrylonitrile, and polyethylene oxide into a container, heating and stirring to dissolve, vacuum degassing, and then spinning through a wet spinning machine, using a 35-40% volume fraction N, N-dimethylacetamide aqueous solution as a coagulation bath, and then stretching in a hot water bath, and finally soaking in hot water and drying to obtain a porous adsorption material for sewage treatment.

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

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

[0010] Furthermore, in step B, the amount of modified polyacrylonitrile is 100 parts by weight and the amount of 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:

[0013] Step (1), adding 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, reacting at 25-40° C. for 18-30 hours, removing the solvent by rotary evaporation, washing with water, and recrystallizing 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 to a reaction container, add 100 parts by weight of the intermediate after stirring, react at 40-65° C. for 4-8 hours, cool and dropwise add hydrochloric acid solution to adjust the pH to 5-6, precipitate, filter and recrystallize the product in dichloromethane to obtain an allyl functional monomer. The reaction formula is:

[0015]

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

[0017] 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, which is then copolymerized with acrylonitrile to obtain a modified polyacrylonitrile containing a carboxyl group, a thiol group and an o-hydroxy Schiff base structure, 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 groups and phenolic hydroxyl groups, which improves the hydrophilicity of the polyacrylonitrile fiber, has higher dispersibility and liquid absorption in water, and is conducive to increasing adsorption sites. At the same time, the carboxyl groups, mercapto groups and o-hydroxy Schiff base structures have strong coordination effects and complex adsorption properties for these metal ions, which significantly improves the adsorption capacity and adsorption properties of the polyacrylonitrile fiber metal ions, and has good practical application in the treatment of metal-containing wastewater. DETAILED DESCRIPTION

[0019] For ease of understanding of the present invention, the present invention will be described more fully below with reference to relevant embodiments. Preferred embodiments of the present invention are provided 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, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0020] Embodiment 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 to 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 to a reaction container, stir, add 6 g of the intermediate, react at 50° C. for 6 h, cool, add hydrochloric acid solution dropwise to adjust the pH to 6, precipitate, 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 allyl functional monomer into a reaction container, add 0.8 g of azobisisobutyronitrile dropwise after stirring, raise the temperature to 65° C., carry out 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 500mL of N,N-dimethylacetamide, 100g of modified polyacrylonitrile, and 10g of polyethylene oxide into a container, heat to 70°C, stir to dissolve, vacuum degass, and then spin through a wet spinning machine, use a 35% volume fraction of N,N-dimethylacetamide aqueous solution as a coagulation bath, and then stretch in a 95°C hot water bath, and finally soak in 60°C hot water for 7 days, dry, and obtain a porous adsorption material for sewage treatment.

[0025] Embodiment 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 to 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 to a reaction container, stir, add 6 g of the intermediate, react at 65 ° C for 4 hours, condense and reflux during the reaction, cool and add hydrochloric acid solution dropwise to adjust the pH to 5, precipitate, filter the product, and recrystallize it in dichloromethane to obtain an allyl functional monomer.

[0028] Step (3), add 500 mL of dimethyl sulfoxide, 80 g of acrylonitrile, and 5.4 g of allyl functional monomer into a reaction container, add 0.85 g of azobisisobutyronitrile dropwise after stirring, raise the temperature to 70° C., carry out polymerization reaction for 18 hours, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain modified polyacrylonitrile.

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

[0030] Embodiment 3:

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

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

[0033] Step (3), add 500 mL of dimethyl sulfoxide, 80 g of acrylonitrile, and 8 g of allyl functional monomer into a reaction container, add 0.88 g of azobisisobutyronitrile dropwise after stirring, raise the temperature to 60° C., carry out polymerization reaction for 24 hours, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain modified polyacrylonitrile.

[0034] Step (4), add 600mL of N,N-dimethylacetamide, 100g of modified polyacrylonitrile, and 12g of polyethylene oxide into a container, heat to 70°C, stir to dissolve, vacuum degassing, and then spin through a wet spinning machine, using a 35% volume fraction of N,N-dimethylacetamide aqueous solution as a coagulation bath, and then stretch in a 95°C hot water bath, and finally soak in 65°C hot water for 7 days, dry, and 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 to a reaction container, add 0.8 g of azobisisobutyronitrile dropwise after stirring, heat to 65° C., carry out 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 500mL N,N-dimethylacetamide, 100g polyacrylonitrile, and 10g polyethylene oxide into a container, heat to 70°C, stir to dissolve, vacuum degassing, and then spin through a wet spinning machine, using a 35% volume fraction N,N-dimethylacetamide aqueous solution as a coagulation bath, and then stretch in a 95°C hot water bath, and finally soak in 60°C hot water for 7 days, dry, and 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 the intermediate (the same preparation method as in Example 1) into a reaction container, add 0.8 g of azobisisobutyronitrile dropwise after stirring, raise the temperature to 65° C., carry out polymerization reaction for 18 hours, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain modified polyacrylonitrile.

[0040] Step (2), add 500mL of N,N-dimethylacetamide, 100g of modified polyacrylonitrile, and 10g of polyethylene oxide into a container, heat to 70°C, stir to dissolve, vacuum degass, and then spin through a wet spinning machine, use a 35% volume fraction of N,N-dimethylacetamide aqueous solution as a coagulation bath, and then stretch in a 95°C hot water bath, and finally soak in 60°C hot water for 7 days, dry, and 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 (structural formula: ), 2.1 g N-allylmethylamine, 3 g triethylamine, react at 30°C for 24 h, remove the solvent by rotary evaporation, wash with water, and recrystallize the product in ethanol to obtain intermediate A with the structural formula

[0043] Step (2), add 200 mL of ethanol, 3.78 g of cysteine, and 1.32 g of potassium hydroxide to the reaction container, stir, add 5.53 g of intermediate A, react at 50° C. for 6 h, cool, add hydrochloric acid solution dropwise to adjust the pH to 6, precipitate, filter, and recrystallize the product in dichloromethane to obtain allyl functional monomer A. The structural formula is

[0044] Step (3), add 400 mL of dimethyl sulfoxide, 80 g of acrylonitrile, and 2.4 g of allyl functional monomer A into a reaction container, add 0.8 g of azobisisobutyronitrile dropwise after stirring, raise the temperature to 65° C., carry out polymerization reaction for 18 h, cool, add water for precipitation, filter, wash with ethanol and hot water, and dry to obtain modified polyacrylonitrile.

[0045] Step (4), add 500mL of N,N-dimethylacetamide, 100g of modified polyacrylonitrile, and 10g of polyethylene oxide into a container, heat to 70°C, stir to dissolve, vacuum degass, and then spin through a wet spinning machine, use a 35% volume fraction of N,N-dimethylacetamide aqueous solution as a coagulation bath, and then stretch in a 95°C hot water bath, and finally soak in 60°C hot water for 7 days, dry, and obtain a porous adsorption material for sewage treatment.

[0046] Prepare 500mL of 60mg / L lead ion Pb 2+ Add 30-60 mg of the porous adsorbent material for sewage treatment to the standard solution, stir and adsorb for 3 hours at 25°C, 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 adsorbent material.

[0047] Table 1

[0048]

[0049] Prepare 500mL of 60mg / L copper ion Cu 2+ Add 30-60 mg of the porous adsorbent material for sewage treatment to the standard solution, stir and adsorb for 2 hours at 25°C, 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 adsorbent material.

[0050] Table 2

[0051]

[0052] Prepare 500mL of cadmium ion with a concentration of 60mg / L 2+ Add 20-40 mg of the porous adsorbent material for sewage treatment to the standard solution, stir and adsorb for 3 hours at 25°C, 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 adsorbent material.

[0053] Table 3

[0054]

[0055]

[0056] As can be seen from the table above, compared with Comparative Example 1, the polyacrylonitrile fiber porous adsorption materials of Examples 1-3 have a higher absorption capacity for Pb 2+ , Cu 2 + 、Cd 2+ They all showed very high adsorption capacity, mainly because polyacrylonitrile fiber contains a large number of hydrophilic groups such as carboxyl and phenolic hydroxyl groups, which improve the hydrophilicity of polyacrylonitrile fiber, and have higher dispersibility and liquid absorption in water, which is beneficial to increase the adsorption sites. At the same time, the carboxyl, thiol and o-hydroxy Schiff base structures have strong coordination effects and complex adsorption properties for these metal ions, which significantly improves the adsorption capacity and adsorption properties of polyacrylonitrile fiber metal ions.

[0057] In Comparative Example 2, the intermediate is copolymerized with acrylonitrile monomer to obtain a porous polyacrylonitrile fiber adsorption material that does not contain carboxyl, thiol and o-hydroxy Schiff base structures, and has low coordination and complex adsorption performance for metal ions, resulting in poor adsorption capacity and adsorption performance.

[0058] Comparative Example 3 utilizes allyl functional monomer A to copolymerize with acrylonitrile monomer to obtain a polyacrylonitrile fiber porous adsorption material that does not contain an o-hydroxy Schiff base structure, and its coordination effect and complex adsorption performance for metal ions are lower than those of the embodiments, resulting in poor adsorption capacity and adsorption performance.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a porous adsorbent material for sewage treatment, characterized in that: The preparation method comprises the following steps: Step A, adding dimethyl sulfoxide, acrylonitrile and allyl functional monomer into a reaction container, adding azobisisobutyronitrile dropwise after stirring, cooling after polymerization, adding water for precipitation, filtering, washing and drying to obtain modified polyacrylonitrile; The structural formula of the allyl functional monomer is Step B, adding N,N-dimethylacetamide, modified polyacrylonitrile, and polyethylene oxide into a container, heating and stirring to dissolve, vacuum degassing, and then spinning through a wet spinning machine, using an N,N-dimethylacetamide aqueous solution as a coagulation bath, and then stretching in a hot water bath, and finally soaking in hot water and drying to obtain a porous adsorption material for sewage treatment.

2. The method for preparing a porous adsorbent material for sewage treatment according to claim 1, characterized in that: In the step A, the amount of acrylonitrile used is 100 parts by weight, the amount of allyl functional monomer used is 3-10 parts by weight, and the amount of azobisisobutyronitrile used is 1-1.1 parts by weight.

3. The method for preparing a porous adsorbent material for sewage treatment according to claim 1, characterized in that: The preparation method of the allyl functional monomer is: Step (1), adding a solvent, 2-hydroxy-5-chloromethylbenzaldehyde, N-allylmethylamine and triethylamine to a reaction vessel, reacting at 25-40° C. for 18-30 hours, removing the solvent by rotary evaporation, washing, and recrystallizing to obtain an intermediate; Step (2), add ethanol, cysteine ​​and potassium hydroxide to the reaction container, stir and then add the intermediate, react at 40-65° C. for 4-8 hours, cool and dropwise add hydrochloric acid solution to adjust the pH to 5-6, precipitate, filter and recrystallize the product to obtain an allyl functional monomer.

4. The method for preparing a porous adsorbent material for sewage treatment according to claim 3, characterized in that: The solvent in step (1) is dichloromethane, ethanol or tetrahydrofuran.

5. The method for preparing a porous adsorbent material for sewage treatment according to claim 3, characterized in that: In the step (1), the amount of 2-hydroxy-5-chloromethylbenzaldehyde used is 100 parts by weight, the amount of N-allylmethylamine used is 42-50 parts by weight, and the amount of triethylamine used is 60-72 parts by weight.

6. The method for preparing a porous adsorbent material for sewage treatment according to claim 3, characterized in that: In the step (2), the amount of cysteine ​​used is 59-63 parts by weight, the amount of potassium hydroxide used is 20-22 parts by weight, and the amount of the intermediate is 100 parts by weight.

7. The method for preparing a porous adsorbent material for sewage treatment according to claim 1, characterized in that: The polymerization reaction temperature in step A is 60-70° C., and the reaction time is 18-24 hours.

8. The method for preparing a porous adsorbent material for sewage treatment according to claim 1, characterized in that: In the step B, the amount of modified polyacrylonitrile is 100 parts by weight and the amount of polyethylene oxide is 10-13 parts by weight.

9. The method for preparing a porous adsorbent material for sewage treatment according to claim 1, characterized in that: The volume fraction of the N,N-dimethylacetamide aqueous solution in step B is 35-40%.

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