Environment-friendly degradable PP cotton filter element and preparation method thereof

Abstract

The invention relates to the technical field of water purification filter elements, and particularly discloses an environment-friendly degradable PP cotton filter element and a preparation method thereof. A main body material of the environment-friendly degradable PP cotton filter element is PP cotton, an adsorbent is loaded on the PP cotton and comprises the following raw materials: 10-20 ml of modified corncob and 12-18 ml of ammonia water, the modified corncob contains a polar functional group, and the polar functional group is a carboxyl functional group; the preparation method comprises the steps that the PP cotton is placed in 10-20 ml of modified corncob for ultrasonic treatment for 5-15 min, soaked for 22-26 h and then soaked in 12-18 ml of an ammonia water solution for 5-7 h, and then natural air drying is conducted. The environment-friendly degradable PP cotton filter element and the preparation method thereof have the advantage that the defect that the heavy metal adsorption performance of the PP cotton filter element is still insufficient can be overcome.

Description

Technical Field

[0001] This application relates to the technical field of water purification filter elements, and more specifically, it relates to an environmentally friendly degradable PP cotton filter element and a preparation method thereof. Background Art

[0002] High molecular polypropylene is the core raw material for making PP cotton filter elements. This substance is non-toxic and odorless, and can reach food-grade safety. The PP cotton filter element made from this high molecular polypropylene through related processes is mainly used for filtration. The PP cotton filter element has a multi-layer gradient structure. Therefore, when water flows through the PP cotton filter element, it mainly penetrates from the outer layer to the inner layer. The characteristic of this filter element is that the closer it is to the inside, the more closely arranged it is, and the filtration accuracy also increases accordingly. Therefore, the characteristic of PP cotton filtering impurities is step by step.

[0003] Currently, since chitosan is a green, environmentally friendly and degradable material that has the ability to complex with most heavy metal ions, it is often used to be loaded on PP cotton to improve the adsorption performance of PP cotton filter elements for heavy metals. However, due to the poor stability of the complex formed by chitosan and heavy metals, it is easy to break the complex and desorb under long-term soaking conditions. Therefore, the adsorption performance of PP cotton filter elements for heavy metals is limited. Summary of the Invention

[0004] In order to improve the defect that the adsorption performance of PP cotton filter elements for heavy metals is still insufficient, this application provides an environmentally friendly degradable PP cotton filter element and a preparation method thereof.

[0005] In the first aspect, an environmentally friendly degradable PP cotton filter element provided by this application adopts the following technical solution: An environmentally friendly degradable PP cotton filter element, the main material of the filter element body is PP cotton. Among them, an adsorbent is loaded on the PP cotton. The adsorbent includes the following raw materials: 10 - 20 ml of modified corn cob and 12 - 18 ml of ammonia water. The modified corn cob contains polar functional groups, and the polar functional group is a carboxyl functional group.

[0006] Since corn cobs are degradable solid wastes in agriculture, with a large quantity but little usage, using corn cobs on PP cotton filter elements is beneficial to improving the utilization rate of agricultural solid wastes. However, the functional groups contained in corn cobs are limited, resulting in weak adsorption performance of corn cobs themselves for heavy metal ions. And carboxyl has a high selectivity for heavy metal ions. Therefore, carboxyl functional groups are introduced into corn cobs for modification, so that the surface of the corn cob contains a large amount of carboxyl, which is beneficial to improving the adsorption ability of corn cobs for heavy metals.

[0007] Preferably, the modified corncob comprises the following raw materials: 45 - 55 g of corncob, 230 - 270 ml of absolute ethanol, 240 - 260 ml of sodium hydroxide solution, 900 - 1000 ml of N-methylpyrrolidone, 95 - 105 ml of 2-bromoisobutyryl bromide, 330 - 370 ml of modified acrylonitrile, 2 - 6 g of cuprous bromide, and 5 - 7 ml of pentamethyldiethylenetriamine.

[0008] Since sodium hydroxide can effectively hydrolyze hemicellulose and cellulose in the corncob under strong alkaline conditions to generate more hydroxyl groups, 2-bromoisobutyryl bromide can react with the hydroxyl groups on the surface of the corncob to introduce bromoalkyl groups, providing reaction sites for subsequent carboxylation modification. Modified acrylonitrile can undergo a polymerization reaction with the functional groups on the surface of the corncob to form a cross-linked structure, enhancing the chemical stability of the corncob.

[0009] Preferably, the preparation method of the modified corncob: Place 45 - 55 g of crushed corncob in a mixed solution of 230 - 270 ml of absolute ethanol and 240 - 260 ml of sodium hydroxide solution, stir continuously. After 0.5 - 1.5 h, rinse with deionized water 2 - 4 times, freeze-dry and then crush and sieve. Subsequently, add 725 - 775 ml of N-methylpyrrolidone, continuously pass nitrogen, and slowly dropwise add a mixed solution of 175 - 225 mL of N-methylpyrrolidone and 95 - 105 ml of 2-bromoisobutyryl bromide at -5 - 5 °C. After dropping, raise the temperature to 55 - 65 °C, stir and react at a constant temperature for 22 - 26 h, then rinse with absolute ethanol 2 - 4 times, vacuum-dry and then crush and sieve. Subsequently, add it to 330 - 370 ml of modified acrylonitrile and shake. Then add 2 - 6 g of cuprous bromide and 5 - 7 ml of pentamethyldiethylenetriamine and react in a water bath at 25 - 35 °C for 22 - 26 h.

[0010] Using atom transfer radical polymerization technology to initiate the polymerization reaction of modified acrylonitrile on the surface of the corncob, and then using sodium hydroxide to hydrolyze the modified acrylonitrile grafted on the surface of the corncob into sodium polyacrylate, so that a large number of carboxyl groups are contained on the surface of the corncob, thereby improving the adsorption effect of the modified corncob on heavy metals under the action of the carboxyl groups.

[0011] Preferably, the modified acrylonitrile comprises the following raw materials: 1 - 2 g of acrylonitrile, 95 - 105 mL of acetic acid solution, 2 - 6 mL of antibacterial nanocellulose, and 0.5 - 0.95 g of potassium persulfate.

[0012] Preferably, the preparation method of the modified acrylonitrile: Place 1 - 2 g of acrylonitrile in 95 - 105 mL of acetic acid solution and stir. Under nitrogen conditions, add 2 - 6 mL of antibacterial nanocellulose and 0.5 - 0.95 g of potassium persulfate, stir at 55 - 65 °C for 2 - 6 h, then wash with deionized water and absolute ethanol 2 - 4 times and then freeze-dry.

[0013] After the filter element has been used for a long time, microorganisms in water will be loaded on the surface of the filter element. Acrylonitrile is a monomer containing a cyano group, and its chemical structure does not contain functional groups that can effectively destroy the cell walls or cell membranes of microorganisms. Antibacterial nanocellulose has good antibacterial properties. After introducing antibacterial nanocellulose into acrylonitrile, the antibacterial properties of acrylonitrile can be effectively improved.

[0014] Preferably, the antibacterial nanocellulose comprises the following raw materials: 0.2 - 0.4 g of 3,3’,4,4’-benzophenone tetracarboxylic dianhydride, 0.1 - 0.3 g of polyphosphoric acid, 8 - 12 g of nanocellulose, 15 - 25 ml of dioxane, and 18 - 22 mL of deionized water.

[0015] Preferably, the preparation method of the antibacterial nanocellulose: Add 0.2 - 0.4 g of 3,3’,4,4’-benzophenone tetracarboxylic dianhydride, 0.1 - 0.3 g of polyphosphoric acid, 8 - 12 g of nanocellulose, and 15 - 25 ml of dioxane into a round-bottom flask, place it in an oil bath at 120 - 160 °C and react for 220 - 260 min. After the reaction, wash it with acetone 2 - 4 times, centrifuge it with a centrifuge, pour off the supernatant, and finally add 18 - 22 mL of deionized water for dispersion.

[0016] Since nanocellulose has the characteristics of natural cellulose such as being renewable and biodegradable, and cellulose has a wide range of sources, with the advantages of low cost, renewable, non-toxic, pollution-free, and easy to modify. The hydroxyl groups on its surface provide the possibility of chemical modification. 3,3’,4,4’-benzophenone tetracarboxylic dianhydride is driven by sunlight, is pollution-free to the environment and has a fast sterilization speed. It contains acid anhydride groups, and the acid anhydride groups can undergo an esterification reaction with hydroxyl groups, thereby improving the antibacterial properties of nanocellulose.

[0017] In a second aspect, the present application provides a preparation method of an environmentally friendly degradable PP cotton filter element, adopting the following technical solution: A preparation method of an environmentally friendly degradable PP cotton filter element, comprising the following steps: S1: Place the PP cotton in 10 - 20 ml of modified corncob and perform ultrasonic treatment for 5 - 15 min. After soaking for 22 - 26 h, immerse it in 12 - 18 ml of ammonia water solution for 5 - 7 h, and then perform natural air drying.

[0018] In summary, the present application has the following beneficial effects: 1. Since corncobs are agricultural solid wastes with a large quantity but little usage, using corncobs in PP cotton filters is beneficial to improving the utilization rate of agricultural solid wastes. However, the functional groups contained in corncobs are limited, resulting in weak adsorption performance of heavy metal ions by themselves. Carboxyl groups have high selectivity for heavy metal ions. Therefore, grafting carboxyl functional groups onto corncobs for modification can make the surface of corncobs contain a large amount of carboxyl groups, which is conducive to improving the adsorption capacity of corncobs for heavy metals.

[0019] 2. Since sodium hydroxide can effectively hydrolyze hemicellulose and cellulose in corncobs under strong alkaline conditions to generate more hydroxyl groups, 2-bromoisobutyryl bromide can react with the hydroxyl groups on the surface of corncobs to introduce bromoalkyl groups, providing reaction sites for subsequent carboxylation modification. Modified acrylonitrile can polymerize with the functional groups on the surface of corncobs to form a cross-linked structure, enhancing the chemical stability of corncobs.

[0020] 3. Using atom transfer radical polymerization technology to initiate the polymerization reaction of modified acrylonitrile on the surface of corncobs, and then using sodium hydroxide to hydrolyze the modified acrylonitrile grafted on the surface of corncobs into sodium polyacrylate, so that the surface of corncobs contains a large amount of carboxyl groups, thereby improving the adsorption of heavy metals by the modified corncobs under the action of grafted carboxyl groups. Specific implementation method

[0021] The present application will be further described in detail below with reference to Examples 1-10 and Comparative Example 1.

[0022] Raw materials Ammonia water CAS: 1336-21-6; corncobs, Laizhou Shuangma Craft Products Co., Ltd.; absolute ethanol CAS: 64-17-5; sodium hydroxide CAS: 1310-73-2; N-methylpyrrolidone CAS: 872-50-4; 2-bromoisobutyryl bromide CAS: 20769-85-1; cuprous bromide CAS: 7787-70-4; pentamethyldiethylenetriamine CAS: 3030-47-5; deionized water CAS: 7732-18-5; acrylonitrile CAS: 107-..."

[0023] Example 1 An environment-friendly and degradable PP cotton filter element comprises the following raw materials: 15 ml of modified corncobs and 15 ml of ammonia water.

[0024] Specifically, the preparation method of the environmentally friendly degradable PP cotton filter element includes the following steps: S1: Weigh 0.3 g of 3,3’,4,4’-diphenylmethanone tetracarboxylic dianhydride, 0.2 g of polyphosphoric acid, 10 g of nanocellulose, and 20 ml of dioxane and add them to a round-bottom flask. Place the flask in an oil bath at 140 °C and react for 240 min. After the reaction, wash it with acetone three times, centrifuge it with a centrifuge, pour off the upper clear liquid, and finally add 20 mL of deionized water for dispersion to obtain antibacterial nanocellulose; S2: Place 1.5 g of acrylonitrile in 100 mL of acetic acid solution and stir. Under nitrogen conditions, add 4 mL of antibacterial nanocellulose and 0.73 g of potassium persulfate. After stirring at 60 °C for 4 h, wash it three times with deionized water and absolute ethanol and then perform freeze-drying to obtain modified acrylonitrile; S3: Place 50 g of crushed corn cob in a mixed solution of 250 ml of absolute ethanol and 250 ml of sodium hydroxide solution, stir continuously. After 1 h, rinse it three times with deionized water, perform freeze-drying and then crush and sieve it. Subsequently, add 750 ml of N-methylpyrrolidone, continuously pass nitrogen, and slowly dropwise add a mixed solution of 200 mL of N-methylpyrrolidone and 100 ml of 2-bromo-2-methylpropionyl bromide at 0 °C. After dropping, raise the temperature to 60 °C, stir and react at a constant temperature for 24 h, rinse it three times with absolute ethanol, perform vacuum drying and then crush and sieve it. Subsequently, add it to 350 ml of modified acrylonitrile and shake it. Then add 4 g of copper bromide and 6 ml of pentamethyldiethylenetriamine and react in a water bath at 30 °C for 24 h; S4: Place the PP cotton in 15 ml of modified corn cob and perform ultrasonic treatment for 10 min. After soaking for 24 h, immerse it in 15 ml of ammonia water solution for 6 h, and then perform natural air drying.

[0025] Examples 2 - 3 The difference from Example 1 is that the addition amounts of the components of the environmentally friendly degradable PP cotton filter element are different, as shown in Table 1 specifically.

[0026] Table 1 Addition amounts of components of the environmentally friendly degradable PP cotton filter element in Examples 1 - 3 (ml) Example 1 Example 2 Example 3 Modified corncob 15 10 20 Ammonia water 15 18 12 Example 4 The difference from Example 1 is that the modified corn cob is replaced with corn cob of the same addition amount.

[0027] Examples 5 - 6 The difference from Example 1 is that the addition amounts of the components of the modified corn cob are different, as shown in Table 2 specifically.

[0028] Table 2 Component addition amounts of modified corncobs in Example 1 and Examples 5 - 6 Example 1 Example 5 Example 6 Corncob 50g 45g 55g Absolute ethanol 250ml 270ml 230ml Sodium hydroxide solution 250ml 260ml 240ml N-Methylpyrrolidone 950ml 900ml 1000ml 2-Bromoisobutyryl bromide 100ml 95ml 105ml Modified acrylonitrile 350ml 370ml 330ml Copper(I) bromide 4g 2g 6g Pentamethyldiethylenetriamine 6ml 7ml 5ml Examples 7 - 8 The difference from Example 1 lies in that the component addition amounts of modified acrylonitrile are different, as specifically shown in Table 3.

[0029] Table 3 Component addition amounts of modified acrylonitrile in Example 1 and Examples 7 - 8 Example 1 Example 7 Example 8 Acrylonitrile 1.5g 2g 1g Acetic acid solution 100ml 95ml 105ml Antibacterial nanocellulose 4ml 2ml 6ml Potassium persulfate 0.73g 0.95g 0.5g Examples 9 - 10 The difference from Example 1 lies in that the component addition amounts of antibacterial nanocellulose are different, as specifically shown in Table 4.

[0030] Table 4 Component addition amounts of antibacterial nanocellulose in Example 1 and Examples 9 - 10 Example 1 Example 9 Example 10 3,3’,4,4’-Benzophenonetetracarboxylic dianhydride 0.3g 0.2g 0.4g Polyphosphoric acid 0.2g 0.1g 0.3g Nanocellulose 10g 12g 8g Dioxane 20ml 25ml 15ml Deionized water 20ml 18ml 22ml Comparative Example 1 The difference from Example 1 lies in that modified corncobs are no longer added.

[0031] Performance detection test I. Adsorption performance test Take three samples from Examples 1 - 10 and Comparative Example 1 respectively, prepare a pure aqueous solution with a lead ion concentration of 50 ppb, pass it through the samples at 4 L / min under 0.2 MPa, measure the lead content in the filter element product water by atomic fluorescence method, calculate the removal rate of lead in water according to the following formula, and take the average value: Removal rate = (raw water lead ion concentration - product water lead ion concentration) ÷ raw water lead ion concentration × 100% The detection data is shown in Table 5.

[0032] Table 5 Adsorption performance test table of Examples 1 - 10 and Comparative Examples 1 - 2 (%) Removal rate Example 1 99.9 Example 2 97.8 Example 3 97.6 Example 4 50.7 Example 5 95.2 Example 6 95.4 Example 7 93.5 Example 8 93.9 Example 9 98.2 Example 10 98.3 Comparative Example 1 43.1 II. Antibacterial performance test Take three samples from Examples 1 - 10 and Comparative Example 1 respectively, and conduct antibacterial performance tests with reference to the standard of GB21551.2 - 2010 "Special Requirements for Antibacterial Materials for Antibacterial, Disinfection, and Purification Functions of Household and Similar Appliances", and then obtain the antibacterial rate and take the average value.

[0033] The detection data is shown in Table 6.

[0034] Table 6 Antibacterial performance test table of Examples 1 - 10 and Comparative Examples 1 - 2 (%) Antibacterial rate Example 1 99.8 Example 2 99.4 Example 3 99.5 Example 4 50.1 Example 5 98.7 Example 6 98.6 Example 7 97.9 Example 8 97.8 Example 9 97.1 Example 10 97.3 Comparative Example 1 45.2 Combining Example 1 and Comparative Example 1 and referring to Table 5 and Table 6, it can be seen that compared with Example 1, the removal rate of heavy metals in Comparative Example 1 has a significant decrease, and at the same time, the antibacterial rate of Comparative Example 1 also has a significant decrease. This shows that compared with the conventional PP cotton filter element, adding modified corn cob to the PP cotton filter element can effectively improve the adsorption performance and antibacterial performance of the PP cotton filter element for heavy metals.

[0035] The reason is that carboxyl groups have a high selectivity for heavy metal ions. Therefore, modifying the corn cob by introducing carboxyl functional groups makes the surface of the corn cob contain a large amount of carboxyl groups, which is beneficial to improving the adsorption ability of the corn cob for heavy metals. Sodium hydroxide can effectively hydrolyze hemicellulose and cellulose in the corn cob under strong alkaline conditions to generate more hydroxyl groups. 2-bromoisobutyryl bromide can react with the hydroxyl groups on the surface of the corn cob to introduce bromoalkyl groups, providing reaction sites for subsequent carboxylation modification. Modified acrylonitrile can polymerize with the functional groups on the surface of the corn cob to form a cross-linked structure, enhancing the chemical stability of the corn cob. Using atom transfer radical polymerization technology to initiate the polymerization of modified acrylonitrile on the surface of the corn cob, and then using sodium hydroxide to hydrolyze the modified acrylonitrile grafted on the surface of the corn cob into sodium polyacrylate, so that the surface of the corn cob contains a large amount of carboxyl groups, thereby improving the adsorption of heavy metals by the modified corn cob under the action of the introduced carboxyl groups.

[0036] Combining Example 1 and Examples 2-3 and referring to Table 5 and Table 6, it can be seen that compared with Example 1, the removal rate of heavy metals in Examples 2 and 3 has a slight decrease, and at the same time, the antibacterial rates of Examples 2 and 3 also have a slight decrease. This shows that the addition amounts of the components of the environmentally friendly degradable PP cotton filter element affect the adsorption performance and antibacterial performance of the PP cotton filter element for heavy metals, and the addition amounts of the components of the environmentally friendly degradable PP cotton filter element in Example 1 are the optimal.

[0037] Combining Example 1 and Example 4 and referring to Table 5 and Table 6, it can be seen that compared with Example 1, the removal rate of heavy metals in Example 4 has a significant decrease, and at the same time, the antibacterial rates of Examples 2 and 3 also have a significant decrease. This shows that compared with adding conventional corn cob, the addition of modified corn cob can effectively improve the adsorption performance and antibacterial performance of the PP cotton filter element for heavy metals.

[0038] The reason is that acrylonitrile is a monomer containing a cyano group, and its chemical structure does not contain functional groups that can effectively destroy the cell walls or cell membranes of microorganisms. However, antibacterial nanocellulose has good antibacterial properties. After introducing antibacterial nanocellulose into acrylonitrile, the antibacterial properties of acrylonitrile can be effectively improved. 3,3’,4,4’-diphenyl ketone tetracarboxylic dianhydride is driven by sunlight, is environmentally friendly and has a fast bactericidal speed. It contains acid anhydride groups, and the acid anhydride groups can undergo an esterification reaction with hydroxyl groups, thereby improving the antibacterial properties of nanocellulose.

[0039] Combining Example 1 and Examples 5 - 6 and referring to Tables 5 and 6, it can be seen that compared with Example 1, the heavy metal removal rates of Examples 5 and 6 show a slight decrease, and at the same time, the antibacterial rates of Examples 5 and 6 also show a slight decrease. This indicates that the addition amounts of the components of the modified corn cob affect the heavy metal adsorption performance and antibacterial performance of the PP cotton filter element, and the addition amounts of the components of the modified corn cob in Example 1 are the optimal.

[0040] Combining Example 1 and Examples 7 - 8 and referring to Tables 5 and 6, it can be seen that compared with Example 1, the heavy metal removal rates of Examples 7 and 8 decrease, and at the same time, the antibacterial rates of Examples 7 and 8 also decrease. This indicates that the addition amounts of the components of the modified acrylonitrile affect the heavy metal adsorption performance and antibacterial performance of the PP cotton filter element, and the addition amounts of the components of the modified acrylonitrile in Example 1 are the optimal.

[0041] Combining Example 1 and Examples 9 - 10 and referring to Tables 5 and 6, it can be seen that compared with Example 1, the heavy metal removal rates of Examples 9 and 10 show a slight decrease, and at the same time, the antibacterial rates of Examples 9 and 10 also show a slight decrease. This indicates that the addition amounts of the components of the antibacterial nanocellulose affect the heavy metal adsorption performance and antibacterial performance of the PP cotton filter element, and the addition amounts of the components of the antibacterial nanocellulose in Example 1 are the optimal.

[0042] This specific embodiment is only an explanation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An environmentally friendly and degradable PP cotton filter element, characterized in that, The main material of the filter element is PP cotton. Among them, an adsorbent is loaded on the PP cotton. The adsorbent includes the following raw materials: 10-20 ml of modified corncob and 12-18 ml of ammonia water. The modified corncob contains polar functional groups, and the polar functional group is a carboxyl functional group.

2. The environmentally friendly and degradable PP cotton filter element according to claim 1, wherein, The modified corncob includes the following raw materials: 45-55 g of corncob, 230-270 ml of absolute ethanol, 240-260 ml of sodium hydroxide solution, 900-1000 ml of N-methylpyrrolidone, 95-105 ml of 2-bromoisobutyryl bromide, 330-370 ml of modified acrylonitrile, 2-6 g of cuprous bromide, 5-7 ml of pentamethyldiethylenetriamine.

3. The environmentally friendly degradable PP cotton filter element according to claim 2, wherein The preparation method of the modified corncob: Place 45-55 g of crushed corncob in a mixed solution of 230-270 ml of absolute ethanol and 240-260 ml of sodium hydroxide solution, stir continuously, after 0.5-1.5 h, rinse with deionized water 2-4 times, freeze-dry and then crush and sieve. Subsequently, add 725-775 ml of N-methylpyrrolidone, continuously pass nitrogen, and slowly dropwise add a mixed solution of 175-225 mL of N-methylpyrrolidone and 95-105 ml of 2-bromoisobutyryl bromide at -5-5 °C. After dropping, raise the temperature to 55-65 °C, stir and react at a constant temperature for 22-26 h, then rinse with absolute ethanol 2-4 times, vacuum dry and then crush and sieve. Subsequently, add it to 330-370 ml of modified acrylonitrile and shake, then add 2-6 g of cuprous bromide and 5-7 ml of pentamethyldiethylenetriamine and react in a water bath at 25-35 °C for 22-26 h.

4. An environment-friendly degradable PP cotton filter element according to claim 3, characterized in that, The modified acrylonitrile includes the following raw materials: 1-2 g of acrylonitrile, 95-105 mL of acetic acid solution, 2-6 mL of antibacterial nanocellulose, 0.5-0.95 g of potassium persulfate.

5. An environment-friendly degradable PP cotton filter element according to claim 4, characterized in that, The preparation method of the modified acrylonitrile: Place 1-2 g of acrylonitrile in 95-105 mL of acetic acid solution and stir. Under nitrogen conditions, add 2-6 mL of antibacterial nanocellulose and 0.5-0.95 g of potassium persulfate, stir at 55-65 °C for 2-6 h, then wash with deionized water and absolute ethanol 2-4 times and then freeze-dry.

6. The environmentally friendly degradable PP cotton filter element according to claim 5, characterized in that, The antibacterial nanocellulose includes the following raw materials: 0.2-0.4 g of 3,3’,4,4’-benzophenone tetracarboxylic dianhydride, 0.1-0.3 g of polyphosphoric acid, 8-12 g of nanocellulose, 15-25 ml of dioxane, 18-22 mL of deionized water.

7. An environmentally friendly degradable PP cotton filter element according to claim 6, characterized in that, The preparation method of the antibacterial nanocellulose: Add 0.2-0.4 g of 3,3’,4,4’-benzophenone tetracarboxylic dianhydride, 0.1-0.3 g of polyphosphoric acid, 8-12 g of nanocellulose, 15-25 ml of dioxane into a round-bottom flask, place it in an oil bath at 120-160 °C and react for 220-260 min. After the reaction, wash with acetone 2-4 times, centrifuge with a centrifuge, pour off the upper clear liquid, and finally add 18-22 mL of deionized water for dispersion.

8. A preparation method of an environment-friendly degradable PP cotton filter element according to any one of claims 1-7, characterized in that, It includes the following steps: S1: Place the PP cotton in 10 - 20 ml of modified corncob and perform ultrasonic treatment for 5 - 15 min. After soaking for 22 - 26 h, impregnate it in 12 - 18 ml of ammonia water solution for 5 - 7 h, and then air dry it naturally.