A method for preparing porous polymer for wastewater treatment

Abstract

The present invention discloses a method for preparing a porous polymer for wastewater treatment, comprising the preparation of a porous gel and a gel flocculant. A gel precursor solution is prepared using acrylamide, hydroxyethyl acrylate, and phenylboric acid, mixed with an adsorbent solution for reaction, and dried to obtain porous xerogel particles. A temperature- and pH-responsive copolymer is then grafted onto the porous xerogel particles in situ. The present invention utilizes the porous xerogel particles as a carrier for an ion adsorbent. The porous structure significantly increases the specific surface area of ​​the material, thereby improving the adsorption capacity for ions in wastewater. Furthermore, the temperature- and pH-responsive copolymer, encapsulated in the outer layer or within the pores, exhibits outstanding flocculation, adsorption, and sedimentation effects in alkaline low-temperature solutions. Subsequent heating or acid neutralization allows for rapid flocculation and sedimentation, facilitating subsequent dehydration and reduction of the flocculant.

Description

Technical Field

[0001] The present invention relates to the technical field of polymers for sewage treatment, and in particular to a method for preparing a porous polymer for wastewater treatment. Background Art

[0002] With the increasingly serious problem of environmental pollution, the development of efficient, low-cost and easy-to-operate pollutant removal technology has become an urgent need, especially for the treatment of highly concentrated saline-alkali wastewater, which requires a large amount of adsorbent and also encounters the problem of heavy metals being difficult to adsorb and remove.

[0003] Researchers have been committed to finding functional materials that can quickly and thoroughly remove pollutants from water. Porous polymers are considered to be an adsorption material with great potential due to their unique structural characteristics.

[0004] Porous polymers are important functional materials with advantages such as high specific surface area, tunable pore structure, and ease of functional modification. They are widely used in environmental protection (such as pollutant adsorption), drug delivery, tissue engineering, and catalysis. Wastewater contains a wide variety of pollutants, including heavy metal ions and organic dyes. Traditional treatment methods such as sedimentation and reverse osmosis have drawbacks such as high cost, complex operation, and poor removal efficiency for certain pollutants.

[0005] However, existing porous polymer materials still have some problems: for example, some materials have low affinity with target ions, resulting in insufficient adsorption capacity; the morphology of some porous polymers is irregular, resulting in insufficient contact area with water, affecting the adsorption effect; in addition, the combined use of porous polymers and flocculants still has process difficulties, specifically the contradictions between adsorption capacity, flocculation speed and sedimentation rate, all of which need to be resolved. Summary of the Invention

[0006] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a method for preparing a porous polymer for wastewater treatment.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a porous polymer for wastewater treatment comprises the following steps:

[0009] S1. Preparation of porous gel:

[0010] S101. Preparation of gel precursor solution:

[0011] References: Preparation and Application of High-Strength Self-Healing Polyacrylamide Hydrogel, Zheng Xiancai, Master's Thesis of Guizhou University:

[0012] Acrylamide (AM), hydroxyethyl acrylate (HEA), and phenylboric acid (PBA) were added to water at a molar ratio of 1:0.2:0.08, with water accounting for 60% of the total weight of the system. Disodium hydrogen phosphate, accounting for 2% of the total weight of the system, was then added. The mixed solution was stirred in an ice bath until all the reactants were completely dissolved.

[0013] Then, add 1% of the total weight of the system as accelerator N,N,N,N-tetramethylethylenediamine (TEMED) and 2% of the total weight of the system as potassium persulfate (KPS), and stir at 25-30°C for 3-5 minutes to prepare gel precursor solution A, which can be used immediately (use within 15 minutes);

[0014] S102, preparation of mixed gel:

[0015] 1) The organic adsorbent and water were stirred and mixed at a weight ratio of 1:5 at 70°C for 30 minutes, and then cooled to 5-10°C to prepare an adsorbent solution;

[0016] 2) The adsorbent solution, gel precursor solution A, and phenylboronic acid (PBA) were mixed in a weight ratio of 1:2:0.05-0.2 for 1 minute, allowed to cool to 0-5°C, poured into a mold, and reacted for 3 hours to obtain wet gel B. According to literature analysis, dynamic borate bonds were formed between the PAM-HEA chains and PBA, and H bonds existed between the hydrogel polymer chains. An AHP hydrogel with a double cross-linked network structure consisting of hydrogen bonds and dynamic borate bonds that encapsulated the adsorbent was constructed, and phenylboronic acid (PBA) was used for cross-linking with the hydroxyl groups loaded on the adsorbent.

[0017] 3) The wet gel B is freeze-dried and crushed into 100-150 mesh to obtain porous xerogel particles C;

[0018] S2. Preparation of gel flocculant:

[0019] S201, gel package:

[0020] N-isopropylacrylamide (PNIPAM), acrylic acid (AA), and hydroxyethyl acrylate (HEA) are added to water at a molar ratio of 10:4-6:1-3, with water accounting for 60% of the total weight of the system. Potassium persulfate (KPS) accounts for 2% of the total weight of the system. The mixture is stirred at 5-10°C for 3-5 minutes, and porous xerogel particles C, accounting for 10% of the total weight of the system, are added. After swelling, the mixture is heated to 40°C and stirred for 2 hours. The mixture is evaporated at 70°C and 0.01 MPa until the water content is less than 20%, thereby obtaining a wet viscous liquid D.

[0021] That is, the excess phenylboric acid remaining in the porous dry gel particles C is cross-linked with the chain side groups with hydroxyethyl acrylate (hydroxyl group), so that the surface of the porous dry gel particles C and the inner wall of the micropores are grafted with acrylamide, acrylic acid, and hydroxyethyl acrylate copolymers. The copolymer has dual response effects of temperature response and pH response. When the temperature is lower than the response temperature Tc, the carboxyl groups in the copolymer chain form hydrogen bonds with water, showing hydrophilicity, high water absorption and swelling rate, and large adsorption capacity, which can improve the flocculation and sedimentation effects; when the temperature is higher than the response temperature Tc, the network hydrogen bonds are destroyed, showing hydrophobicity. The water absorption and swelling rate decreases, the adsorption capacity weakens, and it is used for the later flocculant dehydration; when the pH is lower than the response pH (acidic or neutral), the copolymer chains are in a stretched state, the chain distance is closer, the swelling rate is smaller, the adsorption capacity is weakened, and it is used for the later flocculant dehydration; when the pH is higher than the response pH (alkaline), the copolymer chains are in a contracted state, the chain distance is farther, the swelling rate increases, the adsorption capacity is enhanced, and the flocculation effect can be improved; in order to expand the flocculation adsorption and sedimentation effects, it can be applied to alkaline low-temperature solutions for flocculation and sedimentation, and then dehydrated and reduced by heating or acid neutralization.

[0022] S202, granulation:

[0023] The wet viscous liquid D is freeze-dried and crushed into 100-150 meshes to obtain the finished porous polymer E.

[0024] Preferably, the organic adsorbent in S102 includes any one of anionic polyacrylamide [a molar ratio of amide group, carboxylic acid group and sulfonic acid group is 1:0.24:0.16, customized by Guangdong Shouxin Environmental Protection Materials Technology Co., Ltd., specifically acrylamide, acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) copolymer], 18-crown-6-hydroxycrown ether (purity 99%, Xi'an Qiyue Biotechnology Co., Ltd., specifically 18-crown-6 crown ether prepared by hydroxylation reaction) and COF-5 (purity > 95%, Xi'an Qiyue Biotechnology Co., Ltd., specifically 1,4-phenylenediboronic acid and hexahydroxybenzophenone condensation reaction), which is used to adsorb ions, anionic polyacrylamide adsorbs alkali metal ions, and 18-crown-6-hydroxycrown ether is used to adsorb Cu 2+ 、Hg 2+ or K + , COF-5 is used to adsorb a variety of heavy metal ions.

[0025] Preferably, the conditions for neutralization in S102 and freeze-drying in S202 are -20°C and 2.0 Pa.

[0026] Preferably, the weight ratio of the adsorbent solution, the gel precursor solution A, and phenylboric acid (PBA) in the solution 102 is 1:2:0.1.

[0027] Preferably, the molar ratio of N-isopropylacrylamide (PNIPAM), acrylic acid (AA) and hydroxyethyl acrylate (HEA) in S201 is 10:5:2.

[0028] The application of the finished porous polymer E obtained by the above-mentioned preparation method in sewage includes the following steps: putting the porous polymer E into pure water, with the weight ratio of the porous polymer E to pure water being 1-2:10, dissolving it to obtain a flocculant solution, pouring it into the sewage, with the weight ratio of the porous polymer E to the sewage original solution being 0.1-1:100, and performing adsorption, flocculation and sedimentation treatment to reduce the ion concentration in the sewage.

[0029] Preferably, the sewage is alkaline sewage with a pH ≥ 8.

[0030] Preferably, the treatment temperature of the sewage is 5-30°C.

[0031] Preferably, the weight ratio of the porous polymer E to the sewage raw liquid is 0.5:100.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention first prepares a hybrid gel by combining an adsorbent, a gel precursor solution, and phenylboronic acid. Through the preparation of the gel precursor solution, the formation of the hybrid gel, and subsequent processing, a porous polymer E is ultimately obtained. This porous structure significantly increases the specific surface area of ​​the material, thereby enhancing the adsorption capacity for ions in wastewater, giving the porous gel a high ion adsorption capacity. Furthermore, the adsorbent is not easily detached, facilitating post-processing.

[0034] 2. The present invention can further enhance the specific ions (such as 、 The present invention provides a new idea for the combined use of adsorbents and gels.

[0035] 3. The present invention utilizes excess phenylboric acid remaining in the porous xerogel particles C to crosslink with chain side groups containing hydroxyethyl acrylate (hydroxyl groups), thereby grafting a copolymer of acrylamide, acrylic acid, and hydroxyethyl acrylate onto the surface of the porous xerogel particles C and the inner walls of the micropores. This copolymer exhibits both temperature-responsive and pH-responsive properties, and exhibits outstanding flocculation, adsorption, and sedimentation properties in alkaline low-temperature solutions. Subsequent heating or acid neutralization allows for rapid flocculation and sedimentation, facilitating subsequent dehydration and reduction of the flocculant. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the existing known technologies. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0037] 1. Preparation of porous gel

[0038] 1. Experimental materials:

[0039] Acrylamide (AM), N-isopropylacrylamide (PNIPAM), acrylic acid (AA), N,N,N,N-tetramethylethylenediamine, and disodium hydrogen phosphate (analytical grade) were purchased from Aladdin Reagent; hydroxyethyl acrylate (HEA) (analytical grade) was purchased from MacLean Reagent; phenylboric acid (PBA) (analytical grade) was purchased from Xushuo Reagent; and potassium persulfate (KPS) (analytical grade) was purchased from Jiuding Chemical.

[0040] 2. Preparation of gel precursor solution:

[0041] Reference: Preparation and Application of High-Strength and Self-Healable Polyacrylamide Hydrogel, Zheng Xiancai, Master's Thesis, Guizhou University: Acrylamide (AM), hydroxyethyl acrylate (HEA), and phenylboric acid (PBA) were added to water at a molar ratio of 1:0.2:0.08, with water accounting for 60% of the total weight of the system. Disodium hydrogen phosphate accounting for 2% of the total weight of the system was then added, and the mixed solution was stirred in an ice bath until all the reactants were completely dissolved;

[0042] Then, add 1% of the total weight of the system as accelerator N,N,N,N-tetramethylethylenediamine (TEMED) and 2% of the total weight of the system as potassium persulfate (KPS), and stir at 25-30°C for 3-5 minutes to prepare gel precursor solution A, which can be used immediately (use within 15 minutes);

[0043] 3. Preparation of mixed gel:

[0044] 1) The organic adsorbent and water were stirred and mixed at a weight ratio of 1:5 at 70°C for 30 minutes, and then cooled to 5-10°C to prepare an adsorbent solution;

[0045] The organic adsorbents include any one of anionic polyacrylamide [the molar ratio of amide, carboxylic acid and sulfonic acid groups is 1:0.24:0.16, customized by Guangdong Shouxin Environmental Protection Materials Technology Co., Ltd., specifically copolymerized with acrylamide, acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS)], 18-crown-6-hydroxycrown ether (purity 99%, Xi'an Qiyue Biotechnology Co., Ltd., specifically prepared by hydroxylation of 18-crown-6 crown ether) and COF-5 (purity >95%, Xi'an Qiyue Biotechnology Co., Ltd., specifically prepared by condensation reaction of 1,4-phenylenediboronic acid and hexahydroxybenzophenone) for adsorption of ions. Anionic polyacrylamide adsorbs alkali metal ions, and 18-crown-6-hydroxycrown ether is used to adsorb Cu 2+ 、Hg 2+ or K + , COF-5 is used to adsorb a variety of heavy metal ions.

[0046] 2) The adsorbent solution, gel precursor solution A, and phenylboronic acid (PBA) were mixed at a weight ratio of 1:2:0.05-0.2 for 1 minute, allowed to cool to 0-5°C, poured into a mold, and reacted for 3 hours to obtain wet gel B;

[0047] 3) The wet gel B was freeze-dried at -20°C and 2.0 Pa and crushed to 100-150 mesh to obtain porous xerogel particles C.

[0048] The proportions of the mixed gels in the specific preparation examples are shown in Table 1 below. The porous dry gel particles C obtained in each preparation example were subjected to swelling performance tests as follows: the swelling degree of the hydrogel was measured by weighing. A certain mass of the hydrogel was immersed in an aqueous solution at 25°C until saturated. The wet weight of the saturated swollen hydrogel and the dry weight of the hydrogel after drying in a vacuum oven were measured. The data were recorded and the saturated swelling ratio (Swelling Ratio) of the hydrogel was calculated as follows: SR = (W t -W o ) / W o , where W o is the dry weight of the hydrogel, W t is the wet weight of the hydrogel. All swelling performance test data were repeated three times and the average value was taken (SR% was rounded up).

[0049] Table 1. Formula and swelling properties of mixed gel

[0050]

[0051] The influence of swelling properties was analyzed from Table 1: when the phenylboric acid content was 0 (Comparative Preparation Example 1) or lower (Preparation Example 1), the gel network may be weakly bonded to the adsorbent, and no new cross-linked network was formed, resulting in a higher water absorption efficiency (compared to the hydrogel without adsorbent added in the reference); when the phenylboric acid content was higher (Preparation Example 4 and Comparative Preparation Example 3), the cross-linked network may be denser, resulting in a lower water absorption rate. Therefore, in order to take into account both the water absorption requirements and the subsequent porous requirements, Preparation Example 2 or Preparation Example 3 was selected as the better ratio; COF-5 (Preparation Example 5) or anionic polyacrylamide (Preparation Example 6) was selected to replace 18-crown-6-hydroxycrown ether, and there may be no active hydroxyl group coordinated with phenylboronic acid, and the water absorption rate was slightly improved, especially when the anionic polyacrylamide had stronger water absorption.

[0052] 2. Preparation Method of Porous Polymers

[0053] 1. Preparation of gel flocculant:

[0054] 1) Gel wrap:

[0055] N-isopropylacrylamide (PNIPAM), acrylic acid (AA), and hydroxyethyl acrylate (HEA) are added to water at a molar ratio of 10:4-6:1-3, with water accounting for 60% of the total weight of the system. Potassium persulfate (KPS) accounts for 2% of the total weight of the system. The mixture is stirred at 5-10°C for 3-5 minutes, and porous xerogel particles C, accounting for 10% of the total weight of the system, are added. After swelling, the mixture is heated to 40°C and stirred for 2 hours. The mixture is evaporated at 70°C and 0.01 MPa until the water content is less than 20%, thereby obtaining a wet viscous liquid D.

[0056] That is, the excess phenylboric acid remaining in the porous dry gel particles C is cross-linked with the chain side groups with hydroxyethyl acrylate (hydroxyl group), so that the surface of the porous dry gel particles C and the inner wall of the micropores are grafted with acrylamide, acrylic acid, and hydroxyethyl acrylate copolymers. The copolymer has dual response effects of temperature response and pH response. When the temperature is lower than the response temperature Tc, the carboxyl groups in the copolymer chain form hydrogen bonds with water, showing hydrophilicity, high water absorption and swelling rate, and large adsorption capacity, which can improve the flocculation and sedimentation effects; when the temperature is higher than the response temperature Tc, the network hydrogen bonds are destroyed, showing hydrophobicity. The water absorption and swelling rate decreases, the adsorption capacity weakens, and it is used for the later flocculant dehydration; when the pH is lower than the response pH (acidic or neutral), the copolymer chains are in a stretched state, the chain distance is closer, the swelling rate is smaller, the adsorption capacity is weakened, and it is used for the later flocculant dehydration; when the pH is higher than the response pH (alkaline), the copolymer chains are in a contracted state, the chain distance is farther, the swelling rate increases, the adsorption capacity is enhanced, and the flocculation effect can be improved; in order to expand the flocculation adsorption and sedimentation effects, it can be applied to alkaline low-temperature solutions for flocculation and sedimentation, and then dehydrated and reduced by heating or acid neutralization.

[0057] 2) Granulation:

[0058] The wet viscous liquid D is freeze-dried at -20°C and 2.0 Pa, and crushed into 100-150 meshes to obtain the finished porous polymer E.

[0059] The specific preparation process is shown in Table 2:

[0060] Table 2. Formulation of gel flocculant

[0061]

[0062] 3. Application of porous polymers in sewage treatment:

[0063] 1. Sewage treatment methods:

[0064] The application of the finished porous polymer E of each embodiment and comparative example in sewage comprises the following steps: the porous polymer E is added into pure water, the weight ratio of the porous polymer E to the pure water being 1.5:10, and the flocculant solution is obtained after dissolution, which is poured into the sewage. The sewage is chlor-alkali sewage from a factory (adjusted to a pH of 13), and the weight ratio of the porous polymer E to the sewage stock solution is 0.5:100. Adsorption, flocculation and sedimentation are performed at 25° C. After 24 hours of treatment, the ion concentration in the sewage is recorded. The performance of the finished porous polymer E of each embodiment and comparative example in reducing the ion concentration in sewage is shown in Table 3 below:

[0065] Table 3. Treatment effect of porous polymer on sewage

[0066]

[0067] It should be noted that the total VOC in Table 3 represents the volatile organic compound (VOC) content, specifically including vinyl chloride (VCM), ethylene dichloride (EDC) and other volatile chlorinated hydrocarbons. Table 3 proves that the product of the present invention is not effective in controlling VOCs. It can be used as a pre-treatment measure for aerobic treatment to significantly reduce the ion concentration in wastewater, treat high-concentration saline-alkali wastewater into low-ion water, and then carry out special aerobic treatment to reduce the heavy metal content in sludge.

[0068] Comparing Examples 1-4 with Comparative Examples 1-2, phenylboric acid is beneficial for improving the mixing ability of the adsorbent and the gel. When the amount of phenylboric acid is too little, the cross-linking ability may be weak, causing the adsorbent to separate from the polymer network, making it difficult to settle and separate from the flocculant body, while increasing the organic value of the wastewater (not tested), resulting in a small decrease in the total amount of ions after flocculation. When the amount of phenylboric acid is too much, the cross-linking network may be relatively dense, making it difficult for heavy metal ions with weaker free ability to be adsorbed into the internal adsorbent to form coordination, which also results in a small decrease in the total amount of heavy metal ions.

[0069] Comparing Example 5-6 with Example 2, the effects of the adsorbents were obtained: anionic polyacrylamide was used to adsorb alkali metal ions, and 18-crown-6-hydroxycrown ether was used to adsorb Cu 2+ 、Hg 2+ or K + , COF-5 is used to adsorb a variety of heavy metal ions, proving that the product of the present invention can be used to encapsulate wastewater with different components using specialized adsorbents or composite adsorbents;

[0070] Compared with Example 2, Examples 7-8 and Comparative Examples 3-4 show that as the amount of hydroxyl monomer used in the responsive copolymer increases, the degree of crosslinking of the porous dry gel particles C increases step by step. However, the degree of crosslinking has two effects: on the one hand, a high degree of crosslinking may cause the porous structure of the porous dry gel particles C to be filled, thereby reducing the ion adsorption capacity, especially the heavy ion adsorption capacity; on the other hand, a low degree of crosslinking causes the interaction force between the responsive copolymer and the porous dry gel particles C to decrease, resulting in a higher ion adsorption capacity, but the subsequent flocculation ability is reduced and sedimentation is not easy, so the ion adsorption capacity shows irregular changes.

[0071] 2. Influence of response copolymer:

[0072] The product of Example 2 was used to treat sewage. Hydrochloric acid was used to adjust the ion removal rate at different pH values ​​(pH values ​​were 11 / 9 / 7 / 5) and temperatures (temperature values ​​were 30 / 35). and The total removal rate and turbidity removal rate are shown in Table 4 and Table 5 below:

[0073] Table 4. Effect of pH on ion adsorption rate

[0074]

[0075] As shown in Table 4, when the pH is lowered (the data mutation shows that the product of the present invention responds to pH around 7), the non-heavy metal ion substitution rate is higher, but the overall adsorption capacity of the porous structure is weakened, and it is not conducive to sedimentation.

[0076] Table 5. Effect of temperature on ion adsorption rate

[0077]

[0078] As shown in Table 5, when the temperature is increased (proving that the response temperature of the product of the present invention is between 30-35°C), the suspension is found to have a high sedimentation rate and a large particle aggregation size, resulting in a sharp decrease in turbidity, while the ion removal rate remains basically unchanged. That is, during the treatment process, rapid sedimentation treatment can be carried out by increasing the temperature or increasing the pH, thereby achieving rapid solid-liquid separation.

[0079] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a porous polymer for wastewater treatment, characterized in that: The following steps are involved: S1. Preparation of porous gel: S101. Preparation of gel precursor solution: Acrylamide, hydroxyethyl acrylate, and phenylboric acid were added to water at a molar ratio of 1:0.2:0.08, with water accounting for 60% of the total weight of the system. Disodium hydrogen phosphate accounting for 2% of the total weight of the system was then added, and the mixed solution was stirred in an ice bath until all the reactants were completely dissolved. Then, add 1% of the total weight of the system as accelerator N,N,N,N-tetramethylethylenediamine and 2% of the total weight of the system as potassium persulfate, and stir at 25-30°C for 3-5 minutes to obtain gel precursor solution A, which can be used immediately after preparation; S102, preparation of mixed gel: 1) The organic adsorbent and water were stirred and mixed at a weight ratio of 1:5 at 70°C for 30 minutes, and then cooled to 5-10°C to prepare an adsorbent solution; 2) Mix the adsorbent solution, gel precursor solution A, and phenylboronic acid in a weight ratio of 1:2:0.05-0.2 for 1 minute, let it cool to 0-5°C, pour it into a mold, and react for 3 hours to obtain wet gel B; 3) The wet gel B is freeze-dried and crushed into 100-150 mesh to obtain porous xerogel particles C; S2. Preparation of gel flocculant: S201, gel package: N-isopropylacrylamide, acrylic acid, and hydroxyethyl acrylate are added to water at a molar ratio of 10:4-6:1-3, with water accounting for 60% of the total weight of the system. Potassium persulfate accounting for 2% of the total weight of the system is added, and the mixture is stirred at 5-10°C for 3-5 minutes. Porous xerogel particles C accounting for 10% of the total weight of the system are added. After swelling, the mixture is heated to 40°C and stirred for 2 hours. The mixture is evaporated at 70°C and 0.01 MPa until the water content is less than 20%, thereby obtaining a wet viscous liquid D. S202, granulation: The wet viscous liquid D is freeze-dried and crushed into 100-150 meshes to obtain the finished porous polymer E.

2. The method for preparing a porous polymer for wastewater treatment according to claim 1, characterized in that: The organic adsorbent in S102 includes any one of anionic polyacrylamide, 18-crown-6-hydroxycrown ether and COF-5.

3. The method for preparing a porous polymer for wastewater treatment according to claim 1, characterized in that: The conditions for the neutralization of S102 and freeze-drying of S202 are -20°C and 2.0 Pa.

4. The method for preparing a porous polymer for wastewater treatment according to claim 1, characterized in that: The weight ratio of the adsorbent solution, the gel precursor solution A and phenylboric acid in S102 is 1:2:0.

1.

5. The method for preparing a porous polymer for wastewater treatment according to claim 1, characterized in that: The molar ratio of N-isopropylacrylamide, acrylic acid and hydroxyethyl acrylate in S201 is 10:5:

2.

6. Use of the finished porous polymer E obtained by the preparation method according to any one of claims 1 to 5 in sewage, characterized in that: The method comprises the following steps: adding a porous polymer E into pure water, wherein the weight ratio of the porous polymer E to the pure water is 1-2:10, dissolving the porous polymer E to obtain a flocculant solution, and pouring the solution into sewage, wherein the weight ratio of the porous polymer E to the sewage original solution is 0.1-1:100, and performing adsorption, flocculation and sedimentation treatment to reduce the ion concentration in the sewage.

7. The use of the finished porous polymer E in sewage according to claim 6, characterized in that: The sewage is specifically alkaline sewage with a pH value of ≥8.

8. The use of the finished porous polymer E in sewage according to claim 6, characterized in that: The treatment temperature of the sewage is 5-30°C.

9. The use of the finished porous polymer E in sewage according to claim 6, characterized in that: The weight ratio of the porous polymer E to the sewage raw liquid is 0.5:100.

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