Preparation method of thermo-sensitive gel material and application of thermo-sensitive gel material in recovery of phosphorus in electroplating wastewater

Abstract

The invention discloses a preparation method of a temperature-sensitive gel material and application of the temperature-sensitive gel material in recovery of phosphorus in electroplating wastewater, and belongs to the technical field of gel materials.The preparation method of the temperature-sensitive gel material comprises the following steps that S1, a precursor BA-Fe-MOF is subjected to ultrasonic dispersion in pure water, and dispersion liquid is obtained; s2, adding N-isopropylacrylamide and a cross-linking agent N, N '-methylene bisacrylamide into the dispersion liquid, and after the N-isopropylacrylamide and the cross-linking agent N, N'-methylene bisacrylamide are completely dissolved, filling inert gas into the solution to remove dissolved oxygen; s3, adding an initiator ammonium persulfate into the solution treated in S2, uniformly stirring, adding an accelerant N, N, N ', N'-tetramethylethylenediamine, stirring and mixing, and standing for polymerization to obtain gel; and S4, soaking and washing the gel, and freeze-drying to obtain the temperature-sensitive gel material. The thermo-sensitive gel material disclosed by the invention has good adsorption and removal capability on phosphorus in the electroplating wastewater, and can recycle non-renewable phosphorus while removing the electroplating wastewater.

Description

Technical Field

[0001] This invention belongs to the field of gel material technology, specifically relating to a method for preparing a thermosensitive gel material and its application in the recovery of phosphorus from electroplating wastewater. Background Technology

[0002] In recent years, with social development and increasing public awareness of environmental protection, water pollution has become a major concern (Separation and Purification Technology, 2024, 332: 125736). Industrial wastewater is one of the main sources of water pollution, with the electroplating industry being a key source of industrial wastewater discharge. By 2024, my country's annual discharge of electroplating wastewater had exceeded 400 million tons. Electroplating technology, as a key metal surface treatment process, is widely used in industries such as instrument manufacturing, automobile manufacturing, and electronic equipment (Journal of Environmental Management, 2018, 217: 207-13). Due to the large amount of phosphorus-containing wastewater generated in the metal phosphating process of electroplating, the discharge of untreated wastewater into water bodies can lead to eutrophication, which in turn triggers a series of environmental risks and disrupts the ecological balance of aquatic systems (Energy and Environmental Protection, 2020, 34(01): 65-7). Given the dual nature of phosphorus as both a water pollutant and a non-renewable resource, the environmental engineering field is currently focusing on the research and development of advanced treatment technologies for phosphorus-containing wastewater and phosphorus resource recovery. Breakthroughs in these technologies can not only effectively control the eutrophication process of water bodies, but also achieve closed-loop utilization of phosphorus within industrial systems, which is of strategic significance for promoting cleaner production and the development of a circular economy.

[0003] Among numerous pollutant removal technologies, adsorption is widely used due to its economic efficiency and ease of operation. Adsorption exhibits excellent removal efficiency in treating low-concentration phosphate-polluted water bodies. The process is simple, generates minimal secondary sludge pollution, and allows for resource recycling through adsorbent regeneration (Journal of Hazardous Materials, 2020, 393: 122417). Therefore, the adsorption method for recovering and reusing phosphate is technically feasible. Iron-based organometallic frameworks (Fe-MOFs) possess advantages such as large specific surface area, adjustable pore size, and abundant metal active sites, thus demonstrating significant application value in the field of pollutant adsorption (Applied Surface Science, 2022, 577: 151902). Studies have found that Fe-MOF materials have excellent adsorption effects on P(V), but Fe-MOF materials disperse as solid particles in water, making recovery difficult and limiting their application in water treatment (Chemosphere, 2022, 296:131458). To realize the practical application of Fe-MOF materials in water treatment, this invention immobilizes Fe-MOF materials in a hydrogel carrier for wastewater treatment.

[0004] Temperature-responsive hydrogels based on N-isopropylacrylamide (NIPAAm) can exhibit both hydrophilic and hydrophobic states depending on temperature changes, and have received widespread attention in environmental research (PhysicalChemistry Chemical Physics, 2011, 13(8): 3039-47). By increasing the temperature, NIPAAm gel materials can directly recover pollutants in pure water, which is more energy-efficient and avoids secondary pollution compared to high-salt solution elution recovery methods. This invention discloses the preparation and application of a temperature-sensitive gel material. The temperature-sensitive gel material described in the patent is obtained by crosslinking NIPAAm with the precursor BA-Fe-MOF adsorbent material. The temperature-sensitive gel material prepared by this invention can achieve the adsorption and removal of phosphorus in electroplating wastewater and temperature-controlled recovery in pure water, achieving the goals of cost saving, energy reduction, and effective avoidance of secondary pollution. To date, there have been no reports on the direct recovery of phosphorus in pure water using related temperature-sensitive gel materials.

[0005] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a method for preparing a thermosensitive gel material and its application in the recovery of phosphorus from electroplating wastewater.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a thermosensitive gel material and its application in the recovery of phosphorus from electroplating wastewater. Since the hydrogel NIPAAm prepared based on N-isopropylacrylamide can exhibit both water-absorbing and hydrophobic states according to temperature changes, the adsorption and removal of phosphorus in electroplating wastewater and the direct desorption of phosphorus in pure water can be achieved by changing the water temperature. Compared with the high-salt solution elution and recovery method, it is more energy-efficient and can avoid secondary pollution.

[0008] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0009] A method for preparing a thermosensitive gel material includes the following steps:

[0010] S1. The precursor BA-Fe-MOF was ultrasonically dispersed in pure water to obtain a dispersion.

[0011] S2. Add N-isopropylacrylamide and crosslinking agent N,N'-methylenebisacrylamide to the dispersion. After they are completely dissolved, introduce an inert gas into the solution to remove dissolved oxygen.

[0012] S3. Add the initiator ammonium persulfate to the solution treated by S2, stir evenly, then add the accelerator N,N,N',N'-tetramethylethylenediamine, stir and mix, and let stand to polymerize to obtain a gel.

[0013] S4. The gel is soaked and washed, then freeze-dried to obtain the thermosensitive gel material.

[0014] In one or more embodiments of the present invention, the precursor BA-Fe-MOF is prepared by adding ferric chloride hexahydrate, terephthalic acid and benzoic acid in a molar ratio of 1:1:1 to N,N-dimethylformamide solvent, reacting at 150°C for 12 hours, and then washing, drying and grinding after the reaction.

[0015] A thermosensitive gel material, which is prepared by the method described above.

[0016] Application of the aforementioned thermosensitive gel material in the recycling of phosphorus-containing wastewater.

[0017] In one or more embodiments of the present invention, the phosphorus-containing wastewater is electroplating wastewater.

[0018] In one or more embodiments of the present invention, the application includes using the thermosensitive gel material to adsorb and remove phosphate P(V) from wastewater.

[0019] In one or more embodiments of the present invention, the application includes using the thermosensitive gel material to adsorb and remove phosphite P(III) from wastewater;

[0020] The phosphite P(III) exists in the form of a P(III)-Ni(II) complex, and potassium persulfate is added during the adsorption process.

[0021] A method for recovering phosphorus from electroplating wastewater, using the aforementioned temperature-sensitive gel material, includes the following steps:

[0022] (1) Adsorption step: At 25°C, the thermosensitive gel material is mixed with phosphorus-containing electroplating wastewater for adsorption;

[0023] (2) Desorption and recovery steps: The adsorbed temperature-sensitive gel material is separated, placed in pure water, and desorbed at 42°C to recover phosphorus.

[0024] In one or more embodiments of the present invention, in step (1), the adsorption time is 4 hours and is carried out under oscillation conditions.

[0025] In one or more embodiments of the present invention, in step (2), the desorption time is 8 hours and is carried out under oscillation conditions.

[0026] Compared with the prior art, the temperature-sensitive gel material of the present invention has a good adsorption and removal capacity for phosphorus in electroplating wastewater, and can also recycle non-renewable phosphorus while removing electroplating wastewater, with a good recycling rate.

[0027] The temperature-sensitive gel material of this invention exhibits an orange-red color, determined by its precursor BA-Fe-MOF. This precursor demonstrates excellent adsorption properties for phosphates in wastewater. Immobilizing the precursor onto the hydrogel effectively improves solid-liquid separation while maintaining its good phosphorus removal performance. The material's temperature response is derived from the phase transition of N-isopropylacrylamide upon temperature change; as the temperature rises, the gel material changes from a hydrophilic to a hydrophobic state, thereby enabling complete phosphorus release. Compared to conventional adsorbents, this temperature-sensitive gel material allows for simple temperature control to achieve phosphorus adsorption and removal, demonstrating good operability in the practical treatment of electroplating wastewater.

[0028] The thermosensitive gel material of this invention enables direct desorption and recovery of phosphorus in pure water, avoiding waste of reagents and potential secondary pollution compared to conventional high-salt solution elution and recovery methods. Furthermore, this thermosensitive gel material exhibits excellent stability, maintaining a high total phosphorus recovery rate even after multiple cycles in P(V) and PMS+[P(III)-Ni(II)] systems. Therefore, it shows broad prospects in practical applications, meeting the requirements of green and sustainable development. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the actual finished product of the thermosensitive gel material in one embodiment of the present invention;

[0031] Figure 2 This is a graph showing the change in the amount of total phosphorus adsorbed by the thermosensitive gel material over time in one embodiment of the present invention.

[0032] Figure 3 This is a graph showing the change in the release of total phosphorus by the thermosensitive gel material over time in one embodiment of the present invention. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0034] Example 1: Preparation of precursor BA-Fe-MOF

[0035] Accurately weigh 2.70 g of ferric chloride hexahydrate (FeCl3·6H2O), 1.66 g of terephthalic acid (H2BDC), and 1.22 g of benzoic acid (BA), and add them to 100 mL of N,N-dimethylformamide (DMF) solvent. Stir magnetically at room temperature for 2 hours until the solids are completely dissolved, yielding a homogeneous orange-red mixed solution.

[0036] The above mixed solution was transferred to a 150 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), sealed, and placed in a forced-air drying oven. The reaction was carried out at a constant temperature of 150°C for 12 hours. After the reaction was completed, it was allowed to cool naturally to room temperature.

[0037] Open the reaction vessel, transfer the reaction product to a centrifuge tube, and centrifuge at 8000 rpm for 5 minutes, discarding the supernatant. Wash the precipitate three times each with anhydrous methanol and deionized water, centrifuging after each wash. Place the resulting orange-red solid in a vacuum drying oven at 80℃ for 12 hours. After removal, grind it into powder using an agate mortar and pestle, pass it through a 200-mesh sieve to obtain the precursor material BA-Fe-MOF, which is then sealed and stored for later use. This material has a typical metal-organic framework structure, and its abundant Fe(III) active sites and high affinity for phosphorus are the basis for the subsequent gel's highly efficient adsorption performance.

[0038] Example 2: Preparation of thermosensitive gel material BA-Fe-MOF

[0039] 1.5 g of the precursor BA-Fe-MOF was weighed and ultrasonically dispersed in 30 mL of pure water for 30 min to ensure uniform dispersion. 4.0 g of N-isopropylacrylamide and 0.12 g of crosslinking agent N,N'-methylenebisacrylamide were added to the mixed solution. After complete dissolution and a transparent solution, high-purity nitrogen was introduced for 30 min to remove oxygen. Then, 0.06 g of initiator ammonium persulfate was added to the solution, and after thorough stirring, 0.5 mL of accelerator N,N,N',N'-tetramethylethylenediamine was added. The mixture was rapidly stirred for 30 s and then sealed and allowed to stand for 18 h to obtain a fully polymerized thermosensitive gel material.

[0040] This thermosensitive gel material is named BA-Fe-MOF@NIPAAm, such as Figure 1 As shown, under normal light source conditions, this temperature-sensitive gel material is an orange-red blocky gel.

[0041] Example 3: Adsorption and temperature-controlled desorption performance test of thermosensitive gel material for phosphate P(V)

[0042] Adsorption experiment

[0043] A series of sodium dihydrogen phosphate (NaH2PO4) solutions with different initial concentrations were prepared as simulated P(V) wastewater. Multiple 10.0 mg aliquots of BA-Fe-MOF@NIPAAm dry gel prepared in Example 2 were accurately weighed and placed in 50 mL Erlenmeyer flasks, with 20 mL of the aforementioned P(V) solutions of different concentrations added to each. All Erlenmeyer flasks were placed in a constant temperature water bath shaker at 25°C and shaken at 150 rpm for 4 hours for adsorption. After adsorption, the solution was filtered through a 0.45 μm aqueous filter membrane, and the remaining phosphorus concentration in the filtrate was determined using ammonium molybdate spectrophotometry to calculate the adsorption capacity of the gel. The experimental results are as follows: Figure 2 As shown, BA-Fe-MOF@NIPAAm adsorbed 0.784 mmol / g of total phosphorus in the P(V) system after 1440 min of adsorption. The adsorption effect on total phosphorus was good under room temperature conditions in this experiment.

[0044] Desorption and recovery experiments

[0045] Select the above-mentioned saturated gel sample, for example, obtained from an adsorption experiment with an initial concentration of 4.0 mmol / L. After gently blotting the surface moisture with filter paper, transfer it to another conical flask containing 20 mL of fresh deionized water. Place the conical flask in a constant temperature water bath shaker at 42°C and shake at 150 rpm for 8 hours for temperature-controlled desorption. After desorption, measure the concentration of phosphorus released into the water. Figure 3 As shown, it can be seen that BA-Fe-MOF@NIPAAm released 0.752 mmol / g of total phosphorus from the P(V) system after 1440 min of desorption experiment.

[0046] Adsorption kinetics

[0047] Under the conditions of a fixed initial P(V) concentration of 2.0 mmol / L and an adsorbent dosage of 10 mg / 20 mL, the mixture was shaken at 25℃ and 150 rpm. Samples were taken and measured at different time points to obtain the curve of adsorption capacity changing with time, as shown below. Figure 2 As shown in the figure. The results indicate that adsorption reaches equilibrium within approximately 240 minutes, suggesting that the material exhibits rapid adsorption kinetics.

[0048] Example 4: Test of the oxidative adsorption and temperature-controlled desorption performance of thermosensitive gel material for complexed phosphite P(III)

[0049] Preparation of P(III)-Ni(II) complex solution

[0050] Since phosphorus in electroplating wastewater often exists in the form of phosphite complexes, a simulated wastewater was prepared. Sodium phosphite (Na2HPO3·5H2O) and nickel chloride hexahydrate (NiCl2·6H2O) were weighed and dissolved in deionized water at a P(III) to Ni(II) molar ratio of 1:1 to prepare a P(III)-Ni(II) complex solution of the required concentration.

[0051] Oxidation adsorption experiment

[0052] Accurately weigh multiple 10.0 mg aliquots of BA-Fe-MOF@NIPAAm dry gel into Erlenmeyer flasks, and add 20 mL of P(III)-Ni(II) complexing solution to each. Then, add potassium persulfate (PMS) to each solution, controlling the molar ratio of PMS to P(III) to be 1:1. React at 25°C and 150 rpm for 4 hours with shaking. During this process, PMS oxidizes P(III) to P(V) in situ, while the gel rapidly adsorbs the generated P(V) and any other phosphorus-containing species that may be present through its Fe-MOF component. After the reaction, filter and determine the total phosphorus content, and calculate the adsorption capacity. Figure 2 As shown, BA-Fe-MOF@NIPAAm adsorbed 0.986 mmol / g of total phosphorus in the PMS+[P(Ⅲ)-Ni(Ⅱ)] system after 1440 min of desorption experiment. The adsorption effect on total phosphorus was good under room temperature conditions in this experiment.

[0053] Desorption and recovery experiments

[0054] The adsorbed gel was separated and transferred to 20 mL of deionized water at 42°C. Desorption was carried out by shaking at 150 rpm for 8 hours. The total phosphorus concentration in the desorption solution was measured. Figure 3 As shown, BA-Fe-MOF@NIPAAm released 0.910 mmol / g of total phosphorus from the PMS+[P(Ⅲ)-Ni(Ⅱ)] system after 1440 min of desorption experiment.

[0055] exist Figure 2 and Figure 3 The data comparison shows that the total phosphorus recovery rate in the P(V) system is 95.9%, while the total phosphorus recovery rate in the PMS+[P(Ⅲ)-Ni(Ⅱ)] system is 92.3%.

[0056] Comparative experiment

[0057] A control group without PMS was set up, with all other conditions remaining the same. The results showed that the direct adsorption capacity of the gel for P(III)-Ni(II) was significantly reduced without PMS, demonstrating that the addition of PMS is crucial for the effective removal and recovery of complexed P(III).

[0058] Comparative Example 1: Preparation and phosphorus removal test of pure NIPAAm gel

[0059] Without adding the BA-Fe-MOF precursor, pure NIPAAm gel was prepared by polymerizing 4.0 g NIPAAm and 0.13 g BIS according to the steps in Example 2.

[0060] The adsorption performance of NIPAAm gel for P(V) was tested according to the conditions of Example 3. The results are shown in Table 1. The pure NIPAAm gel hardly adsorbed phosphate, and its adsorption amount was negligible. This comparison demonstrates the core role of BA-Fe-MOF as the active adsorbent component in the composite gel, and that phosphorus adsorption and removal cannot be achieved by relying solely on the temperature-sensitive NIPAAm network.

[0061] Table 1. Comparison of adsorption properties between pure NIPAAm gel and BA-Fe-MOF@NIPAAm

[0062] Material Name BA-Fe-MOF dosage Adsorption capacity of P(V) (mmol / g) in conclusion Pure NIPAAm gel 0 g < 0.1 (negligible) The temperature-sensitive network itself hardly adsorbs phosphorus, proving that BA-Fe-MOF is the key active adsorption component. BA-Fe-MOF@NIPAAm 1.5 g ~0.8 (See Example 3) The composite exhibits excellent adsorption performance.

[0063] Comparative Example 2: Direct Application and Recycling Issues of BA-Fe-MOF Powder

[0064] The BA-Fe-MOF powder prepared in Example 1 was used directly to conduct the P(V) adsorption experiment according to the conditions of Example 3.

[0065] The results, as shown in Table 2, demonstrate that BA-Fe-MOF powder itself exhibits excellent adsorption performance, with a maximum adsorption capacity comparable to that of the composite gel. However, after adsorption, the powder remains suspended in the solution, making rapid and complete solid-liquid separation difficult through natural sedimentation or simple filtration, requiring time-consuming and energy-intensive operations such as centrifugation. More importantly, unlike the gel, the adsorbed powder cannot achieve efficient phosphorus desorption in pure water through simple temperature changes. Traditional acid-base elution generates secondary wastewater, and significant powder loss occurs during repeated centrifugation and washing. This comparison highlights the advantages of immobilizing BA-Fe-MOF in the NIPAAm gel carrier: it retains high adsorption activity, solves the engineering challenges of recycling and reusing powder materials, and introduces a novel, green, temperature-controlled desorption mechanism.

[0066] Table 2. Comparison of comprehensive properties between BA-Fe-MOF powder and BA-Fe-MOF@NIPAAm gel

[0067] Comparison Projects BA-Fe-MOF powder BA-Fe-MOF@NIPAAm gel (this invention) Adsorption performance Excellent Excellent solid-liquid separation Difficult, requires centrifugation, and the operation is cumbersome. Easy, quick physical removal or filtering Desorption method Chemical elution with acid / alkali / salt solution is required. Only pure water needs to be heated to 42°C Recycle The elution and regeneration process is complex, and the powder is easily lost. Direct temperature-controlled desorption, reusable after water washing in conclusion High performance but difficult to apply in practice High performance and easy to apply in practice

[0068] The thermosensitive gel material provided by this invention successfully prepares a novel intelligent adsorption material by ingeniously combining Fe-MOF material with high phosphorus adsorption capacity with a thermosensitive polymer network. This material not only exhibits excellent adsorption and removal capabilities for different forms of phosphorus (free P(V) and complexed P(III)) in electroplating wastewater, but also achieves efficient recovery of adsorbed phosphorus in pure water through simple temperature control (adsorption at 25℃ vs. desorption at 42℃). Furthermore, the material itself has good stability and can be recycled multiple times. The entire process requires no additional chemical eluents, avoiding secondary pollution. It is simple to operate, energy-saving, and environmentally friendly, and has broad application prospects in the fields of advanced electroplating wastewater treatment and phosphorus resource recovery.

[0069] Reagent Name Manufacturers Purity type <![CDATA[Iron(III) chloride hexahydrate (FeCl3·6H2O)]]> Shanghai Aladdin Biochemical Technology Co., Ltd. Analytical Pure <![CDATA[Terephthalic acid (C8H6O4)]]> Shanghai Aladdin Biochemical Technology Co., Ltd. Analytical Pure <![CDATA[Benzoic acid (C7H6O2)]]> Shanghai Aladdin Biochemical Technology Co., Ltd. Analytical Pure <![CDATA[N,N-Dimethylformamide (C3H7NO)]]> Shanghai Aladdin Biochemical Technology Co., Ltd. Analytical Pure <![CDATA[Methanol (CH4O)]]> Shanghai Aladdin Biochemical Technology Co., Ltd. Analytical Pure <![CDATA[N-Isopropylacrylamide (C6H 11 NO)]]> Shanghai Aladdin Biochemical Technology Co., Ltd. 98% (including stabilizer MEHQ) <![CDATA[N,N'-Methylenebisacrylamide (C7H 10 N2O2)]]> Shanghai Aladdin Biochemical Technology Co., Ltd. Analytical Pure <![CDATA[N,N,N’,N’-tetramethylethylenediamine (C6H 16 N2)]]> Shanghai Aladdin Biochemical Technology Co., Ltd. Analytical Pure <![CDATA[(NH4)2S2O8]]> Shanghai Aladdin Biochemical Technology Co., Ltd. Analytical Pure <![CDATA[Nitrogen (N2)]]> - High-purity nitrogen <![CDATA[Sodium dihydrogen phosphate (Na2HPO4)]]> Shanghai E-En Chemical Technology Co., Ltd. Analytical Pure <![CDATA[Sodium phosphite (Na2HPO3·5H2O)]]> Shanghai E-En Chemical Technology Co., Ltd. Analytical Pure <![CDATA[Nickel chloride (NiCl2·6H2O)]]> Shanghai E-En Chemical Technology Co., Ltd. Analytical Pure <![CDATA[Potassium peroxymonosulfate (KHSO5·0.5KHSO4·0.5K2SO4)]]> Shanghai E-En Chemical Technology Co., Ltd. <![CDATA[42 % - 46 % (calculated as KHSO5)]]>

[0070] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0071] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a thermosensitive gel material, characterized in that, Includes the following steps: S1. The precursor BA-Fe-MOF was ultrasonically dispersed in pure water to obtain a dispersion. S2. Add N-isopropylacrylamide and crosslinking agent N,N'-methylenebisacrylamide to the dispersion. After they are completely dissolved, introduce an inert gas into the solution to remove dissolved oxygen. S3. Add the initiator ammonium persulfate to the solution treated by S2, stir evenly, then add the accelerator N,N,N',N'-tetramethylethylenediamine, stir and mix, and let stand to polymerize to obtain a gel. S4. The gel is soaked and washed, then freeze-dried to obtain the thermosensitive gel material.

2. The preparation method according to claim 1, characterized in that, The precursor BA-Fe-MOF is prepared by adding ferric chloride hexahydrate, terephthalic acid and benzoic acid in a molar ratio of 1:1:1 to N,N-dimethylformamide solvent, reacting at 150°C for 12 hours, and then washing, drying and grinding after the reaction.

3. A thermosensitive gel material, characterized in that, It is prepared by the method described in claim 1 or 2.

4. The application of the thermosensitive gel material as described in claim 3 in the recycling of phosphorus-containing wastewater.

5. The application according to claim 4, characterized in that, The phosphorus-containing wastewater is electroplating wastewater.

6. The application according to claim 4, characterized in that, The application includes using the thermosensitive gel material to adsorb and remove phosphate P(V) from wastewater.

7. The application according to claim 4, characterized in that, The application includes using the thermosensitive gel material to adsorb and remove phosphite P(III) from wastewater; The phosphite P(III) exists in the form of a P(III)-Ni(II) complex, and potassium persulfate is added during the adsorption process.

8. A method for recovering phosphorus from electroplating wastewater, characterized in that, The use of the thermosensitive gel material according to claim 3 includes the following steps: (1) Adsorption step: At 25°C, the thermosensitive gel material is mixed with phosphorus-containing electroplating wastewater for adsorption; (2) Desorption and recovery steps: The adsorbed temperature-sensitive gel material is separated, placed in pure water, and desorbed at 42°C to recover phosphorus.

9. The recycling method according to claim 8, characterized in that, In step (1), the adsorption time is 4 hours and the process is carried out under oscillation conditions.

10. The recycling method according to claim 8, characterized in that, In step (2), the desorption time is 8 hours and is carried out under oscillation conditions.

Images