Chitosan polyacrylic acid biological filler and preparation method thereof

Abstract

The invention relates to the technical field of biological stuffing, and discloses chitosan polyacrylic acid biological stuffing and a preparation method thereof.The chitosan polyacrylic acid biological stuffing is prepared from chitosan, acrylic acid, an initiator, mesoporous silica and hydrofluoric acid, and the initiator is an electrolytic reaction solution of 1-butylpyridine chloride and aluminum sulfate; the filler is formed by polymerizing chitosan and acrylic acid, has high biocompatibility, and uses mesoporous silica and hydrofluoric acid as a template agent and a template removing agent, so that developed gaps are generated in the chitosan acrylic acid biological filler, the specific surface area is increased, and the colonization quantity of microorganisms is increased; according to the filler, an electrolytic reaction solution of 1-butylpyridine chloride and aluminum sulfate is used as an initiator for copolymerization of chitosan and acrylic acid, so that chitosan and acrylic acid form a polymer, and in addition, the structural strength of the chitosan polyacrylic acid biological filler can be improved by the electrolyte, and the structural stability of the biological filler is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biological fillers, in particular to a chitosan polyacrylic acid biological filler and a preparation method thereof. Background Art

[0002] Bioremediation is a commonly used sewage treatment method, which utilizes the metabolic effects of microorganisms or plants to degrade pollutants in sewage. It has the advantages of low cost and no secondary pollution to the environment. Free microorganisms are mainly used in traditional sewage treatment, but free microorganisms have problems such as low concentration of effective degradation bacteria per unit volume, slow reactor startup, easy loss of bacteria, and competition with indigenous bacteria, poor resistance to toxic invasion, and sensitivity to drastic changes in hydraulic conditions. Therefore, in order to overcome the above problems, the prior art provides a technical solution for immobilizing microorganisms. For example, publication number CN113087282B discloses a sewage treatment device containing a fixed microbial filler. In this technical solution, polyurethane foam is used as a carrier for bacteria and algae, which increases the effective bacterial concentration per unit volume of white rot fungi and improves the sewage treatment capacity of microorganisms. Currently, the materials used for biological fillers are mainly inorganic materials or polymer materials. These materials have poor biocompatibility and usually do not play a beneficial role in bacterial growth. Therefore, it is of great significance to provide a biological filler with high biocompatibility. Summary of the Invention

[0003] The present invention provides a chitosan polyacrylic acid biofiller and a preparation method thereof. The filler is formed by polymerization of chitosan and acrylic acid. The material has high biocompatibility. The filler uses mesoporous silica and hydrofluoric acid as a template and a de-templating agent to generate developed voids inside the chitosan polyacrylic acid biofiller, thereby increasing the specific surface area and the number of microbial colonization. The filler also uses an electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate as an initiator for the copolymerization of chitosan and acrylic acid, so that the chitosan and acrylic acid form a polymer. In addition, the electrolyte can also increase the structural strength of the chitosan polyacrylic acid biofiller and significantly improve the structural stability of the biofiller.

[0004] The specific technical solutions of the present invention are: A chitosan polyacrylic acid biofiller comprises, by weight, 20-40 parts of chitosan, 60-80 parts of acrylic acid, and 0.01-0.04 parts of an initiator. The raw materials also include mesoporous silica and hydrofluoric acid, wherein the initiator is an electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate.

[0005] Preferably, the molar ratio of 1-butylpyridinium chloride to aluminum sulfate is 2 to 4:1.

[0006] Preferably, the porosity of the mesoporous silica is 60-70%.

[0007] Preferably, the mesoporous silica is prepared by a sol-gel method.

[0008] The present invention provides a chitosan polyacrylic acid biofiller, which is a biofiller with high biocompatibility formed by the polymerization of chitosan and acrylic acid. The filler has a developed internal pore structure and a large specific surface area, and can provide growth space for microorganisms so that the microorganisms can colonize and regenerate the interior of the biofiller. The microbial loading capacity can be significantly increased, and the use of the biofiller loaded with microorganisms in sewage treatment significantly improves the sewage treatment efficiency.

[0009] The initiator used in the chitosan-polyacrylic acid polymerization reaction of the present invention is an electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate. The present invention finds that the electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate can generate thiosulfate, which can be used as an initiator for the polymerization reaction of chitosan and acrylic acid. In addition, the electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate can significantly increase the uniformity and structural strength of the chitosan-polyacrylic acid polymer, ensuring that the filler has a certain structural stability when used in a solution and ensuring that the loaded microorganisms are not affected. In addition, the electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate can also improve the high temperature and high pressure resistance of the chitosan-polyacrylic acid, so that the chitosan-polyacrylic acid will not soften or deform after high-pressure sterilization.

[0010] A method for preparing the chitosan polyacrylic acid biofiller comprises the following steps: (1) adding 1-butylpyridinium chloride and aluminum sulfate to water to prepare an electrolyte, and performing an electrolytic reaction on the electrolyte using an electrolysis device to prepare an electrolytic reaction solution; (2) Chitosan and acrylic acid are added to water and dissolved, and then the mesoporous silica is immersed in the polymerization solution and ultrasonically dispersed; then the electrolytic reaction solution is slowly added dropwise to the polymerization solution to carry out a polymerization reaction to form a composite; (3) Immersing the complex in hydrofluoric acid to dissolve the mesopores to prepare chitosan polyacrylic acid biofiller Preferably, the electrolysis reaction conditions include: voltage 3-6V, current 20-50mA / cm 2 .

[0011] Preferably, the polymerization reaction conditions include: reaction temperature of 40 to 60° C., and reaction time of 2 to 4 hours.

[0012] Preferably, a polymerization inhibitor is used to terminate the polymerization reaction, and the amount of the polymerization inhibitor is 0.05 to 0.1%.

[0013] Preferably, the polymerization inhibitor is hydroquinone.

[0014] Preferably, the concentration of the hydrofluoric acid solution is 10-20%.

[0015] The present invention also provides a method for preparing the chitosan polypropionic acid biofiller. The method uses mesoporous silica as a template and hydrofluoric acid as a de-templating agent to prepare the chitosan polypropionic acid biofiller. Hydrofluoric acid does not significantly affect chitosan polyacrylic acid and can also dissolve silica. Therefore, the present invention selects mesoporous silica as the template and hydrofluoric acid as the de-templating agent. The chitosan and acrylic acid are fully filled in the pore structure of the mesoporous silica, and an initiator is used to polymerize the chitosan and acrylic acid to form a composite of a polymer and silica. The composite is then placed in a hydrofluoric acid solution to dissolve the silica to prepare a chitosan polypropionic acid biofiller with porous pores. The method is simple to operate and can be produced on a large scale.

[0016] Compared with the existing technology, this application has the following technical effects: (1) The filler is formed by polymerization of chitosan and acrylic acid, and the material has high biocompatibility; (2) The filler uses mesoporous silica and hydrofluoric acid as a template and a de-template agent to create developed voids inside the chitosan acrylic biofiller, thereby increasing the specific surface area and the number of microbial colonization; (3) The filler also uses an electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate as an initiator for the copolymerization of chitosan and acrylic acid, so that chitosan and acrylic acid form a polymer; the electrolyte can also increase the structural strength of the chitosan polyacrylic acid biofiller and significantly increase the structural stability of the biofiller; the electrolyte can also improve the high temperature and high pressure resistance of the chitosan polyacrylic acid, so that it will not soften and deform after high-pressure sterilization. DETAILED DESCRIPTION

[0017] The present invention will be further described below with reference to the embodiments.

[0018] Example 1: A method for preparing a chitosan polyacrylic acid biofiller comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 5 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0019] Example 2: A method for preparing a chitosan polyacrylic acid biofiller comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 4 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0020] Example 3: A method for preparing a chitosan polyacrylic acid biofiller comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 2:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 5 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0021] Example 4: A method for preparing a chitosan polyacrylic acid biofiller comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 4:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 5 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0022] Example 5: A method for preparing a chitosan polyacrylic acid biofiller comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 5 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 60%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0023] Example 6: A method for preparing a chitosan polyacrylic acid biofiller comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 5 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 70%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0024] Example 7: A method for preparing a chitosan polyacrylic acid biofiller comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 5 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 50°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization reaction was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 20%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0025] Example 8: A method for preparing a chitosan polyacrylic acid biofiller comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 5 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 2:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 40°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0026] Comparative Example 1: Comparative Example 1 Compared with Example 1, potassium persulfate was used as the initiator, and the method included the following steps: (1) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, chitosan was dissolved in deionized water, acrylic acid was added and stirred evenly, and then mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. 3% potassium persulfate was added and polymerization reaction was carried out for 4 h. 0.1% of a polymerization inhibitor (hydroquinone) was then added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0027] Comparative Example 2: Comparative Example 2, compared with Example 2, in which the electrolysis voltage is too low, comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 3 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0028] Comparative Example 3: Comparative Example 3, compared with Example 1, has an electrolysis voltage that is too high and comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 6 V and the current was 30 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0029] Comparative Example 4: Comparative Example 4, compared with Example 1, has a low electrolysis current and comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 6 V and the current was 20 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0030] Comparative Example 5: Comparative Example 5, compared with Example 1, has a too high electrolysis current and comprises the following steps: (1) 1-Butylpyridinium chloride and aluminum sulfate were weighed in a molar ratio of 3:1, and 1-Butylpyridinium chloride and aluminum sulfate were dissolved in water to prepare an electrolyte. The electrolyte was injected into the electrolytic cell of the electrolysis device for electrolytic reaction to prepare an electrolytic reaction solution. The voltage of the electrolytic reaction was 6 V and the current was 40 mA / cm 2 , the anode of the electrolysis device is a graphite electrode and the cathode is a ferroelectric electrode; (2) Chitosan and acrylic acid were weighed in a molar ratio of 3:1, and chitosan was dissolved in deionized water. Acrylic acid was added and stirred evenly. Then, mesoporous silica (porosity 65%) was added and ultrasonically dispersed for 2 h. The mixture was heated to 60°C and placed in a nitrogen atmosphere. The electrolytic reaction solution was added and polymerization was carried out for 4 h. Then, 0.1% of a polymerization inhibitor (hydroquinone) was added to prepare a mesoporous silica chitosan polyacrylic acid complex. (3) The mesoporous silica chitosan polyacrylic acid composite was processed into the desired shape and immersed in a hydrofluoric acid solution (mass fraction of 10%) for reaction for 24 hours. After the immersion, it was washed with distilled water until the washing solution was neutral, and then placed in an 80°C oven for drying to prepare a chitosan polyacrylic acid biofiller.

[0031] Test Example 1: The grafting rate, tensile strength, and specific surface area of ​​the chitosan polyacrylic acid biofillers prepared in Examples 1 to 8 and Comparative Examples 1 to 5 were tested; The grafting rate was tested by infrared spectroscopy; The tensile strength test is carried out in accordance with the contents disclosed in ASTM D638 Standard Test Method for Tensile Properties of Plastics; The specific surface area is tested according to the contents disclosed in GB / T19587-2017 Determination of Specific Surface Area of ​​Solid Substances by BET Method for Gas Adsorption; The test results are shown in Table 1.

[0032] Table 1 Grafting rate, tensile strength and specific surface area of ​​chitosan polyacrylic acid biofiller Grafting rate (%) tensile strength Specific surface area Example 1 78％ 2MPa 370 Example 2 73％ 1.9MPa 366 Example 3 67％ 1.8MPa 360 Example 4 69％ 1.8MPa 368 Example 5 74％ 1.9MPa 365 Example 6 72％ 1.9MPa 362 Example 7 68％ 1.8MPa 359 Example 8 64％ 1.7MPa 357 Comparative Example 1 60％ 1.5MPa 350 Comparative Example 2 66％ 1.6MPa 361 Comparative Example 3 68％ 1.8MPa 366 Comparative Example 4 65％ 1.7MPa 363 Comparative Example 5 71％ 1.9MPa 367 As shown in Table 1, the chitosan polyacrylic acid biofillers prepared in Examples 1 to 8 have a grafting rate of 60-78%, a tensile strength of 1.5-2.0 MPa, and a specific surface area of ​​350-370. It can be seen that the chitosan polyacrylic acid biofiller provided by the present invention has excellent uniformity, structural strength and specific surface area.

[0033] In Comparative Example 1, potassium persulfate was used as an initiator. After comparing the results of Comparative Example 1 and Example 1, it was found that the grafting rate and tensile strength of Example 1 were significantly higher than those of Comparative Example 1. The above results indicate that the use of the electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate as an initiator can significantly improve the uniformity and structural strength of the chitosan polyacrylic acid biofiller, ensure that the biofiller will not be easily destroyed and lost during subsequent use, and improve the durability of the biofiller.

[0034] Comparative Examples 2, 3, 4 and 5 respectively explored the electrolysis reaction conditions of 1-butylpyridinium chloride and aluminum sulfate. The results showed that the electrolysis voltage and electrolysis current had a great influence on the grafting rate of the prepared chitosan polyacrylic acid. When the electrolysis voltage and electrolysis current were too low or too high, the grafting rate of the chitosan polyacrylic acid would be reduced.

[0035] Test Example 2: The chitosan polyacrylic acid biofillers prepared in Examples 1 to 8 and Comparative Example 1 were used to treat domestic sewage. Before use, the biofillers were sterilized under high pressure and loaded with microorganisms. The biofillers loaded with microorganisms were loaded into a sewage treatment device to treat wastewater from a domestic sewage treatment plant. The initial COD concentration of the wastewater was 490 mg / L, and the ammonia nitrogen concentration was 36 mg / L. The COD concentration and ammonia nitrogen concentration in the water were tested after 24 hours of reaction. After three months of treatment, the biofillers were removed and the retention rate of the biofillers was tested. The test results are shown in Table 2.

[0036] Table 2 Test results COD concentration (mg / L) Ammonia nitrogen concentration (mg / L) Retention rate (%) State of biological filler after autoclaving Example 1 72.5 9 85％ No significant changes Example 2 80.2 10.9 80％ No significant changes Example 3 85.3 12.3 75％ No significant changes Example 4 82.4 11.2 78％ No significant changes Example 5 87.4 14.1 73％ No significant changes Example 6 85.3 12.6 76％ No significant changes Example 7 78.5 9.6 83％ No significant changes Example 8 86.2 11.9 75％ No significant changes Comparative Example 1 102 9.5 70％ Softening deformation occurs As shown in Table 2, after 24 hours of treatment of domestic sewage using the chitosan polyacrylic acid biofiller provided in Examples 1 to 8, the COD removal rate in the water reached 85%, and the ammonia nitrogen removal rate reached 75%. After three months of use, the biofiller retention rate was 85%. These results demonstrate that the chitosan polyacrylic acid biofiller prepared in the present invention can significantly reduce the COD and ammonia nitrogen concentrations in domestic sewage while exhibiting excellent durability.

[0037] Comparative Example 1 is a biological filler prepared using potassium persulfate as an initiator. Compared with Example 1, the COD removal rate and ammonia nitrogen removal rate in the water body of Comparative Example 1 after 24 hours of domestic sewage treatment are not significantly different from those of Example 1. However, the retention rate of the biological filler of Comparative Example 1 after three months of treatment is only 70%. It can be seen that Comparative Example 1 is easily damaged and lost during long-term use, and its durability is poor.

[0038] In addition, by analyzing and observing the state of the biofillers after high-pressure sterilization of Examples 1 to 8 and Comparative Example 1, it was found that the chitosan polyacrylic acid biofiller prepared in Comparative Example 1 softened and deformed after high-pressure sterilization, and the structural strength was reduced, while the chitosan polyacrylic acid biofiller prepared in Examples 1 to 8 of the present invention did not undergo significant changes. Therefore, in the subsequent use process, the chitosan polyacrylic acid biofiller prepared by the present invention will have excellent durability, while the durability of the chitosan polyacrylic acid biofiller of Comparative Example 1 is poor. The above content shows that the present invention can significantly improve the high temperature and high pressure resistance of chitosan polyacrylic acid when using the electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate as an initiator, thereby ensuring that the structural strength of chitosan polyacrylic acid is not significantly reduced under high-pressure sterilization conditions.

[0039] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A chitosan polyacrylic acid biofiller, characterized in that: The raw materials include, by mass, 20-40 parts of chitosan, 60-80 parts of acrylic acid and 0.01-0.04 parts of initiator. The raw materials also include mesoporous silica and hydrofluoric acid. The initiator is an electrolytic reaction solution of 1-butylpyridinium chloride and aluminum sulfate.

2. The chitosan polyacrylic acid biofiller according to claim 1, characterized in that: The molar ratio of 1-butylpyridinium chloride to aluminum sulfate is 2-4:

1.

3. The chitosan polyacrylic acid biofiller according to claim 1, characterized in that: The porosity of mesoporous silica is 60~70%.

4. The chitosan polyacrylic acid biofiller according to claim 1 or 3, characterized in that: Mesoporous silica is prepared by the sol-gel method.

5. A method for preparing the chitosan polyacrylic acid biofiller according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) adding 1-butylpyridinium chloride and aluminum sulfate into water to prepare an electrolyte, and performing an electrolytic reaction on the electrolyte using an electrolytic device to prepare an electrolytic reaction solution; (2) Chitosan and acrylic acid are added to water and dissolved, and then the mesoporous silica is immersed in the polymerization solution and ultrasonically dispersed; then the electrolytic reaction solution is slowly added dropwise to the polymerization solution to carry out polymerization reaction to form a composite; (3) The complex is immersed in hydrofluoric acid to dissolve the mesopores to prepare chitosan polyacrylic acid biofiller.

6. The preparation method according to claim 5, characterized in that: The conditions of the electrolysis reaction include: voltage 3-6 V, current 20-50 mA / cm 2 .

7. The preparation method according to claim 5, characterized in that: The polymerization reaction conditions include: reaction temperature of 40-60° C., and reaction time of 2-4 h.

8. The preparation method according to claim 5, characterized in that: The polymerization reaction is terminated by using a polymerization inhibitor, the dosage of which is 0.05~0.1%.

9. The preparation method according to claim 8, characterized in that: The polymerization inhibitor is hydroquinone.

10. The preparation method according to claim 5, characterized in that: The concentration of hydrofluoric acid solution is 10~20%.