A gel material with nitrogen adsorption function, its preparation and application

Abstract

A nitrogen-adsorption gel material, its preparation, and its application are disclosed. The nitrogen-adsorption gel material comprises a porous network structure cross-linked with polyvinyl alcohol and phytic acid, and the porous network structure is loaded with zeolite particles. The preparation method involves adding zeolite to a copolymer solution of polyvinyl alcohol and phytic acid under alkaline conditions, and then adding a cross-linking agent to the resulting polyvinyl alcohol-phytic acid-zeolite mixture for cross-linking and curing. The cross-linked and cured mixture is subjected to liquid-solid separation, and the solids after liquid-solid separation are washed until the pH is neutral. The nitrogen-adsorption gel material is used to reduce the ammonia nitrogen content in water bodies through adsorption, or added to a bioreactor to couple a biological reaction for deep denitrification. The material of this invention has good sphericity and excellent ammonia nitrogen adsorption performance.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, specifically to a gel material with nitrogen adsorption function, its preparation and application. Background Technology

[0002] Zeolite (ZL) is a hydrous aluminosilicate crystal with numerous internal channels and a three-dimensional, open framework structure, making it widely used as an ion exchanger and adsorbent in wastewater treatment. The pore size of zeolite molecules ranges from 0.5 to 1.2 nm, allowing only ions of suitable size to enter the zeolite interior. Replacing aluminum with silicon in the aluminosilicate structure results in a negatively charged system, enabling the adsorption of certain cations. NH4 + The ionic radius of -N is only 0.286 nm, so it can easily enter the internal pores of zeolite and exchange ions with cations inside the crystal, thereby achieving the adsorption of NH4. + The purpose of -N. Natural zeolite is inexpensive and an ideal material for ammonia nitrogen adsorption.

[0003] When using zeolite powder to adsorb ammonia nitrogen, the zeolite powder tends to agglomerate due to electrostatic interactions between tiny particles, resulting in a significant reduction in specific surface area and consequently a decrease in adsorption performance. Furthermore, zeolite powder easily forms silt, making it difficult to separate and reuse from water bodies. These problems limit the widespread application of zeolite powder materials in the adsorption field. Preparing zeolite into spherical particulate adsorbents is currently the main solution. The main methods for preparing zeolite microspheres include polymerization and powder bonding to form spheres. In the process of preparing particulate adsorbents using the powder bonding to form spheres method, such as the preparation methods in patents with publication numbers CN104492404A, CN112642390A, and CN107096498A, a high-temperature calcination method of 400–800℃ is usually required to eliminate the uneven interface between powders and improve the stability of microspheres. The high-temperature calcination process not only increases energy consumption but may also destroy the crystal structure of zeolite and reduce its adsorption performance. In addition, other powder additives with smaller particle sizes are often used in the sphere-making process. These particles can easily clog the pores of the adsorbent and reduce its adsorption capacity.

[0004] Stable and efficient spherical NH4 can be prepared by immobilizing zeolite in a three-dimensional gel network using polymerization. +-N adsorbent. Polyvinyl alcohol (PVA) is a highly water-soluble, highly compatible, and non-biotoxic polymer material with wide applications in environmental protection, agriculture, biology, and medical and health fields. Its molecular chain has a large number of hydroxyl groups, which readily form a gel network structure through intramolecular and intermolecular hydrogen bonds. According to the research of Putra et al. (doi.org / 10.1016 / j.seppur.2019.116351), spherical NH4+ adsorbents were prepared by combining polyvinyl alcohol gel materials with zeolite particles. + -N adsorbents are considered a feasible approach, as their preparation conditions are mild, and zeolites can be stably loaded into polyvinyl alcohol gel networks to achieve excellent adsorption effects. However, hydrogel materials obtained by simple chemical cross-linking of polyvinyl alcohol have drawbacks such as dense cross-linking of the gel network and poor porosity. Furthermore, the rapid cross-linking rate of the outer layer during preparation often results in a dense shell structure on the surface, affecting the mass transfer performance of the material. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a gel material with nitrogen adsorption function, its preparation and application. Zeolite is fixed in a copolymer gel network of polyvinyl alcohol and phytic acid (PA). Phytic acid is used as a small molecule dopant to improve the gel network structure and improve the specific surface area and pore capacity of the material. At the same time, the material has good ammonia nitrogen adsorption performance and biocompatibility.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A nitrogen-adsorption gel material comprises a porous network structure co-crosslinked with polyvinyl alcohol and phytic acid, wherein the porous network structure is loaded with zeolite particles.

[0008] The method for preparing a nitrogen-adsorption gel material includes: adding zeolite to a copolymer of polyvinyl alcohol and phytic acid under alkaline conditions; adding a crosslinking agent to the resulting polyvinyl alcohol-phytic acid-zeolite mixture for crosslinking and curing; performing liquid-solid separation on the crosslinked and cured mixture; and washing the solid after liquid-solid separation until the pH is neutral.

[0009] In the polyvinyl alcohol-phytic acid-zeolite mixture, the concentration of zeolite is 1.37wt% to 4.09wt%, the concentration of polyvinyl alcohol is 6.82wt% to 8.93wt%, and the concentration of phytic acid is 0.20wt% to 0.41wt%.

[0010] The cross-linking and curing reaction time is 36–60 h.

[0011] The preparation method of the polyvinyl alcohol-phytic acid-zeolite mixture includes the following steps: adding polyvinyl alcohol powder to water and dissolving it under water bath heating and stirring conditions to obtain a polyvinyl alcohol solution; adding sodium hydroxide solution and phytic acid solution to the polyvinyl alcohol solution in sequence under continuous heating and stirring conditions and carrying out a copolymerization reaction; and then adding zeolite to the alkaline polyvinyl alcohol-phytic acid copolymer solution.

[0012] The heating temperature is 80-90℃, the polyvinyl alcohol dissolution time is 1.5-2.0h, the polyvinyl alcohol solution concentration is 9.10-11.50wt%, and the polyvinyl alcohol copolymerization reaction time with phytic acid is 0.3-0.5h.

[0013] The sodium hydroxide solution has a concentration of 3-5 wt%, the phytic acid solution has a concentration of 60-70 wt%, and the mass ratio of sodium hydroxide to phytic acid is 0.90-1.50:0.35-0.60.

[0014] The zeolite mentioned is natural clinoptilolite modified by impregnation with NaCl solution.

[0015] The crosslinking agent is a mixed solution of boric acid and calcium chloride, and the ratio of boric acid, calcium chloride and water is 4-5g:1-2g:100-120mL.

[0016] The nitrogen-adsorption gel material described above is light brown and spherical in appearance, with a particle size of 3-5 mm and a specific surface area of ​​18.8-21.3 m². 2 / g, with an average pore volume of 0.18–0.26 cm³. 3 / g, density is 1.19~1.29g / cm³ 3 The swelling rate is 312.8–527.6%, and the settling velocity is 247.0–274.2 m / h.

[0017] The aforementioned nitrogen-adsorption gel material is used to reduce the ammonia nitrogen content in water through adsorption, or to be added to a bioreactor to couple a biological reaction for deep denitrification.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] This invention relates to polyvinyl alcohol (PVA) gel materials, using phytic acid as a small molecule dopant to prepare zeolite-supported PVA and phytic acid copolymer gel materials. The preparation process is mild and simple. The resulting nitrogen-adsorbing gel material possesses a well-connected and uniformly distributed three-dimensional network structure, exhibiting excellent specific surface area and pore volume, as well as excellent mass transfer performance and NH4+ adsorption capacity. +-N adsorption performance. Polyvinyl alcohol and phytic acid are both biocompatible organic materials, and the nitrogen adsorption gel material described herein possesses excellent biocompatibility and biofilm formation performance. This invention provides a gel material with nitrogen adsorption function, which has wide applications and can adsorb NH4+ from wastewater. + -N can be physically removed, or it can be added to a bioreactor to improve the system's ammonia nitrogen removal efficiency and overall denitrification performance. Attached Figure Description

[0020] Figure 1 This is a photograph of the gel material prepared in Example 1.

[0021] Figure 2 This is a photograph of the gel material prepared in Example 2.

[0022] Figure 3 This is a photograph of the gel material prepared in Example 3.

[0023] Figure 4 This is a physical image of the gel material prepared in Comparative Example 1.

[0024] Figure 5 The image shows the microstructure of the gel material prepared in Example 1, as scanned by electron microscopy (SEM).

[0025] Figure 6 The image shows the microstructure of the gel material prepared in Example 2 using SEM.

[0026] Figure 7 The image shows the microstructure of the gel material prepared in Example 3 using SEM.

[0027] Figure 8 The image shows the microstructure of the gel material prepared in Comparative Example 1 using SEM.

[0028] Figure 9 The NH4+ of the gel materials prepared in Examples 1-5 and Comparative Examples 1 and 2 + -N adsorption curve. Detailed Implementation

[0029] The present invention will be further described below with reference to the embodiments.

[0030] Example 1: A method for preparing a gel material with nitrogen adsorption function, comprising the following steps:

[0031] (a) Preparation of polyvinyl alcohol solution: Polyvinyl alcohol powder was added to deionized water and dissolved in a water bath at 85°C for 1.8 h with stirring to obtain a polyvinyl alcohol solution with a concentration of 10.70 wt%.

[0032] (b) Preparation of alkaline polyvinyl alcohol-phytic acid copolymer solution: Under the water bath stirring conditions in step (a), a 4 wt% NaOH solution was added to the completely dissolved polyvinyl alcohol solution, and then a 65 wt% phytic acid solution was added. The mass ratio of sodium hydroxide to phytic acid was 1.20:0.50. The reaction was heated and stirred for 0.4 h to obtain an alkaline polyvinyl alcohol-phytic acid copolymer solution.

[0033] (c) Preparation of polyvinyl alcohol-phytic acid-zeolite mixture: Natural clinoptilolite was modified with NaCl solution as a modifier, dried and passed through a 200-mesh sieve; under the water bath stirring conditions in step (a), the modified zeolite was added to the polyvinyl alcohol-phytic acid copolymer solution obtained in step (b), and after stirring and mixing evenly, a polyvinyl alcohol-phytic acid-zeolite mixture was obtained. The concentration of zeolite in the mixture was 2.73 wt%, the concentration of polyvinyl alcohol was 8.19 wt%, and the concentration of phytic acid was 0.34 wt%.

[0034] (d) Preparation of gel material: Using a mixture of boric acid, calcium chloride and water in a ratio of 4g:1g:100mL as a crosslinking agent, the polyvinyl alcohol-phytic acid-zeolite mixture obtained in step (c) was added dropwise to the crosslinking agent under continuous magnetic stirring. The mixture droplets quickly crosslinked and solidified into gel beads. After reacting for 48 hours, the mixture was removed with a filter screen and then rinsed several times with deionized water until the pH was neutral, resulting in a light brown PVA / PA / ZL gel material with a diameter of 3-5mm.

[0035] Example 2, a method for preparing a gel material with nitrogen adsorption function, comprising the following steps:

[0036] (a) Preparation of polyvinyl alcohol solution: Polyvinyl alcohol powder was added to deionized water and dissolved in a water bath at 85°C for 1.8 h with stirring to obtain a polyvinyl alcohol solution with a concentration of 9.10 wt%.

[0037] (b) Preparation of alkaline polyvinyl alcohol-phytic acid copolymer solution: Under the water bath stirring conditions in step (a), a 3 wt% NaOH solution was added to the completely dissolved polyvinyl alcohol solution, and then a 70 wt% phytic acid solution was added. The mass ratio of sodium hydroxide to phytic acid was 0.90:0.60. The mixture was heated and stirred for 0.5 h to obtain an alkaline polyvinyl alcohol-phytic acid copolymer solution.

[0038] (c) Preparation of polyvinyl alcohol-phytic acid-zeolite mixture: Natural clinoptilolite was modified with NaCl solution as a modifier, dried and passed through a 200-mesh sieve; under the water bath stirring conditions in step (a), the modified zeolite was added to the polyvinyl alcohol-phytic acid copolymer solution obtained in step (b), and after stirring and mixing evenly, a polyvinyl alcohol-phytic acid-zeolite mixture was obtained. The concentration of zeolite in the mixture was 4.09 wt%, the concentration of polyvinyl alcohol was 6.82 wt%, and the concentration of phytic acid was 0.41 wt%.

[0039] (d) Preparation of gel material: Using a mixture of boric acid, calcium chloride and water in a ratio of 5g:2g:100mL as a crosslinking agent, the polyvinyl alcohol-phytic acid-zeolite mixture obtained in step (c) was added dropwise to the crosslinking agent under continuous magnetic stirring. The mixture droplets quickly crosslinked and solidified into gel beads. After reacting for 36 hours, the mixture was removed with a filter screen and then rinsed several times with deionized water until the pH was neutral, resulting in a light brown PVA / PA / ZL gel material with a diameter of 3-5mm.

[0040] Example 3, a method for preparing a gel material with nitrogen adsorption function, comprising the following steps:

[0041] (a) Preparation of polyvinyl alcohol solution: Polyvinyl alcohol powder was added to deionized water and dissolved in a water bath at 90°C for 1.5 h with stirring to obtain a polyvinyl alcohol solution with a concentration of 11.50 wt%.

[0042] (b) Preparation of alkaline polyvinyl alcohol-phytic acid copolymer solution: Under the water bath stirring conditions in step (a), a 5 wt% NaOH solution was added to the completely dissolved polyvinyl alcohol solution, and then a 60 wt% phytic acid solution was added. The mass ratio of sodium hydroxide to phytic acid was 1.50:0.35. The reaction was heated and stirred for 0.3 h to obtain an alkaline polyvinyl alcohol-phytic acid copolymer solution.

[0043] (c) Preparation of polyvinyl alcohol-phytic acid-zeolite mixture: Natural clinoptilolite was modified with NaCl solution as a modifier, dried and passed through a 200-mesh sieve; under the water bath stirring conditions in step (a), the modified zeolite was added to the polyvinyl alcohol-phytic acid copolymer solution obtained in step (b), and after stirring and mixing evenly, a polyvinyl alcohol-phytic acid-zeolite mixture was obtained. The concentration of zeolite in the mixture was 1.37 wt%, the concentration of polyvinyl alcohol was 8.93 wt%, and the concentration of phytic acid was 0.41 wt%.

[0044] (d) Preparation of gel material: Using a mixture of boric acid, calcium chloride and water in a ratio of 4g:1g:120mL as a crosslinking agent, the polyvinyl alcohol-phytic acid-zeolite mixture obtained in step (c) was added dropwise to the crosslinking agent under continuous magnetic stirring. The mixture droplets quickly crosslinked and solidified into gel beads. After reacting for 60 hours, the mixture was removed with a filter screen and then rinsed several times with deionized water until the pH was neutral, resulting in a light brown PVA / PA / ZL gel material with a diameter of 3-5mm.

[0045] Example 4 is the same as Example 1 except that the concentration of polyvinyl alcohol in step (a) is 11.50 wt%, the concentration of zeolite in the polyvinyl alcohol-phytic acid-zeolite mixture in step (c) is 2.71 wt%, the concentration of polyvinyl alcohol is 8.93 wt%, and the concentration of phytic acid is 0.20 wt%. This example also yields a light brown PVA / PA / ZL gel material with a diameter of 3-5 mm.

[0046] Example 5 is the same as Example 1 except that the polyvinyl alcohol concentration in step (a) is 9.10 wt%, the zeolite concentration in the polyvinyl alcohol-phytic acid-zeolite mixture in step (c) is 2.77 wt%, the polyvinyl alcohol concentration is 6.92 wt%, and the phytic acid concentration is 0.41 wt%. This example also yields a light brown PVA / PA / ZL gel material with a diameter of 3-5 mm.

[0047] Application Example 1: A gel material was prepared according to Example 1. The gel material was added to a biological deep denitrification reactor, with the added gel material accounting for 30% of the reactor's working volume. The reactor influent contained NH4. + -N=NO3 - -N and TN concentrations are 40 mg / L, sodium acetate is used as the organic carbon source, and the influent COD / NO3 ratio is... - With -N = 3.0 and a hydraulic retention time of 7.7 h, the nitrogen removal efficiency of the bioreactor was monitored, and the results are shown in Table 2.

[0048] Application Example 2: Change the NH4+ inlet water of the reactor in Application Example 1. + -N=NO3 - -N and TN concentrations are 25 mg / L, sodium acetate is used as the organic carbon source, and the influent COD / NO3 ratio is... - With -N = 3.0 and a hydraulic retention time of 5.1 h, the nitrogen removal efficiency of the bioreactor was monitored, and the results are shown in Table 2.

[0049] Application Example 3: Change the NH4+ in the reactor inlet water in Application Example 1. + -N=NO3 - -N and TN concentrations are 15 mg / L, sodium acetate is used as the organic carbon source, and the influent COD / NO3 ratio is...- With -N = 3.0 and a hydraulic retention time of 1.9 h, the nitrogen removal efficiency of the bioreactor was monitored, and the results are shown in Table 2.

[0050] Application Example 4: Change the NH4+ in the reactor inlet water in Application Example 3. + -N=NO3 - -N and TN concentrations are 15 mg / L, sodium acetate is used as the organic carbon source, and the influent COD / NO3 ratio is... - -N=3.0, the hydraulic retention time of the reactor was 0.6h, and the nitrogen removal effect of the bioreactor was monitored. The results are shown in Table 2.

[0051] Comparative Example 1: No zeolite was added, and the remaining steps were the same as in Example 1 to obtain PVA / PA gel material.

[0052] Comparative Example 2, without the addition of phytic acid, followed the same steps as in Example 1 to obtain PVA / ZL gel material.

[0053] Comparative Example 3: A gel material was prepared according to Comparative Example 1 and added to a biological deep denitrification reactor. The volume of the added material accounted for 30% of the reactor's working volume. The reactor influent contained NH4+. + -N=NO3 - -N and TN concentrations are 40 mg / L, sodium acetate is used as the organic carbon source, and the influent COD / NO3 ratio is... - With -N = 3.0 and a hydraulic retention time of 7.7 h, the nitrogen removal efficiency of the reactor was monitored, and the results are shown in Table 2.

[0054] Comparative Example 4: The NH4+ in the influent of the biological deep denitrification reactor in Comparative Example 2 was changed. + -N=NO3 - -N and TN concentrations are 25 mg / L, sodium acetate is used as the organic carbon source, and the influent COD / NO3 ratio is... - With -N = 3.0 and a hydraulic retention time of 5.1 h, the nitrogen removal efficiency of the reactor was monitored, and the results are shown in Table 2.

[0055] Comparative Example 5: The NH4 influent to the biological deep denitrification reactor in Comparative Example 2 was changed. + -N=NO3 - -N and TN concentrations are 15 mg / L, sodium acetate is used as the organic carbon source, and the influent COD / NO3 ratio is... - With -N = 3.0 and a hydraulic retention time of 1.9 h, the nitrogen removal efficiency of the reactor was monitored, and the results are shown in Table 2.

[0056] Comparative Example 6: The NH4 influent to the biological deep denitrification reactor in Comparative Example 4 was changed. + -N=NO3 --N and TN concentrations are 15 mg / L, sodium acetate is used as the organic carbon source, and the influent COD / NO3 ratio is... - With -N = 3.0 and a hydraulic retention time of 0.6 h, the nitrogen removal efficiency of the reactor was monitored, and the results are shown in Table 2.

[0057] The diameter, specific surface area, pore volume, density, swelling ratio, sedimentation velocity, and biofilm formation of the gel materials prepared in all examples (i.e., Examples 1, 2, 3, 4, and 5) and Comparative Examples 1 and 2 were tested, and the results are shown in Table 1. Electron micrographs of the physical samples and microstructures of Examples 1, 2, 3, and Comparative Example 1 are shown in Table 1. Figures 1-8 .

[0058] 5g (wet weight) of the gel material prepared in all examples (i.e., Examples 1, 2, 3, 4, 5) and Comparative Examples 1 and 2 were subjected to NH4 reaction. + -N adsorption performance test: NH4Cl was prepared using NH4Cl as the solute. + An adsorption solution with a -N concentration of 25 mg / L was used. The gel material was added to 50 mL of the adsorption solution, and the adsorption experiment was conducted in a constant-temperature shaker at 30℃ and 200 rpm. Samples were taken at regular intervals to measure the adsorption capacity. The experimental results are as follows: Figure 9 As shown in Table 1, the adsorption rate results are presented.

[0059] Table 1. Properties of the gel materials from Examples 1-5 and Comparative Examples 1-2 and NH4+ + Summary table of -N adsorption characteristics

[0060]

[0061]

[0062] Table 2 summarizes the denitrification performance results of reactors in Application Examples 1-4 and Comparative Examples 3-6.

[0063]

[0064] The nitrogen adsorption gel material provided by this invention has good NH4 content. + -N adsorption performance and biocompatibility. The test results for Examples 1-3 and Comparative Example 1 are shown in Table 1. Figures 5-9 It can be seen that all the examples have good NH4 content. + -N adsorption effect, comparative example 1 (without zeolite) versus NH4+ + The adsorption capacity of -N is weak, and the NH4 in the gel material is... + -N adsorption capacity mainly comes from the loaded zeolite particles. Zeolite has a high density, and as the amount of zeolite added increases, the density and sedimentation velocity of the gel material gradually increase. Adding zeolite helps to increase the pore size and pore volume of the material, which is conducive to mass transfer and the attachment and growth of organisms.

[0065] As can be seen from Examples 1-5 and Comparative Example 2 in Table 1, all examples exhibit good specific surface area, pore volume, and biofilm formation. However, in Comparative Example 2 without PA, compared to Example 1, the specific surface area and pore volume of the material significantly decreased, which affected the material's microbial adhesion and mass transfer performance, as well as its biofilm formation and NH4+. + -N adsorption capacity also decreased significantly.

[0066] As can be seen from Application Examples 1-4 and Comparative Examples 3-5 in Table 2, the bioreactor filled with PVA / PA / ZL gel material with added zeolite has a higher removal efficiency of ammonia nitrogen and total nitrogen compared to PVA / PA gel material.

[0067] In summary, the nitrogen adsorption functional gel material provided by this invention exhibits excellent morphology, superior specific surface area and pore volume, and excellent ammonia nitrogen adsorption characteristics. With increasing zeolite content and improved material ratio, the adsorption efficiency for ammonia nitrogen can reach over 80%. Furthermore, the nitrogen adsorption functional gel material provided by this invention has good biocompatibility and can be filled into bioreactors to construct nitrogen adsorption coupled with deep biological denitrification, thereby improving the removal efficiency of ammonia nitrogen and total nitrogen in the reactor.

[0068] The present invention has been described above by way of example. It should be noted that, without departing from the core of the present invention, any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort fall within the protection scope of the present invention.

Claims

1. A method for preparing a gel material with nitrogen adsorption function, characterized in that: A gel material with nitrogen adsorption function includes a porous network structure of polyvinyl alcohol and phytic acid copolymer crosslinking, and the porous network structure is loaded with zeolite particles. The gel material with nitrogen adsorption function has light brown spherical appearance, particle size of 3-5mm, specific surface area of 14.7-21.3m 2 / g, average pore volume of 0.18-0.26cm 3 / g, density of 1.17-1.29g / cm 3 , swelling rate of 303.6-443.2%, and sedimentation velocity of 223.7-274.2m / h; The method for preparing a nitrogen-adsorption gel material includes: adding zeolite to a copolymer of polyvinyl alcohol and phytic acid under alkaline conditions; adding a crosslinking agent to the resulting polyvinyl alcohol-phytic acid-zeolite mixture for crosslinking and curing; performing liquid-solid separation on the crosslinked and cured mixture; and washing the solid after liquid-solid separation until the pH is neutral. The preparation method of the polyvinyl alcohol-phytic acid-zeolite mixture includes the following steps: adding polyvinyl alcohol powder to water and dissolving it under heating and stirring conditions to obtain a polyvinyl alcohol solution. The heating temperature is 80~90℃, and the polyvinyl alcohol dissolution time is 1.5~2.0h. Under continuous heating and stirring conditions, sodium hydroxide solution and phytic acid solution are added to the polyvinyl alcohol solution sequentially and a copolymerization reaction is carried out. The mass percentage of sodium hydroxide solution is 3~5wt%, the mass percentage of phytic acid solution is 60~70wt%, the mass ratio of sodium hydroxide to phytic acid is 0.90~1.50:0.35~0.60, and the copolymerization reaction time of polyvinyl alcohol and phytic acid is 0.3~0.5h. Then, zeolite is added to the alkaline polyvinyl alcohol-phytic acid copolymer solution. In the polyvinyl alcohol-phytic acid-zeolite mixture: the concentration of zeolite is 1.37wt% to 4.09wt%, the concentration of polyvinyl alcohol is 6.82wt% to 8.93wt%, and the concentration of phytic acid is 0.20wt% to 0.41wt%. The zeolite mentioned is a natural clinoptilolite modified by impregnation with NaCl solution; The crosslinking agent is a mixed solution of boric acid and calcium chloride, and the ratio of calcium chloride, boric acid and water is 4~5g:1~2g:100~120mL.

2. The preparation method according to claim 1, characterized in that: The cross-linking and curing reaction time is 36–60 h.

3. The application of the nitrogen-adsorption functional gel material prepared by the preparation method according to any one of claims 1-2, characterized in that: It is used to reduce the ammonia nitrogen content in water through adsorption, or added to a bioreactor to couple a biological reaction for deep denitrification.

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