Preparation method and application of quaternary ammonium modified polyester fiber material for water treatment

Abstract

The application discloses a preparation method and application of a quaternary ammonium modified polyester fiber material for water treatment, belongs to the field of water treatment material processing, and relates to surface chemical modification of polyester fiber. The polyester fiber carrier is used as a substrate, the carrier has a columnar structure, the cross section of the carrier is pentagonal or circular, the diameter of the carrier is 0.5-1 cm, and the length of the carrier is 1-2 cm. Glycerol methacrylate is grafted to the surface of the polyester fiber in the presence of an initiator to introduce an epoxy group; an organic amine is used to open the ring of the epoxy group and to carry out amination to introduce an amine group; and a halogenated alkyl is used to alkylate the amine group, so that a quaternary ammonium group is formed, and a modified polyester fiber material containing the quaternary ammonium group on the surface is obtained. The obtained material can be used for removing phosphate in water, and is suitable for removing phosphorus in domestic sewage and industrial wastewater.

Description

Technical Field

[0001] This invention belongs to the field of water treatment material processing, and relates to the surface chemical modification of fiber materials. Specifically, it relates to a method for preparing quaternized ammonium modified polyester fiber material for water treatment and its application in wastewater phosphorus removal. Background Technology

[0002] Phosphorus (P) is one of the major limiting nutrients that causes eutrophication in water bodies. Even at low concentrations (e.g., around 0.02 mg / L), it can induce excessive proliferation of algae and aquatic plants, leading to eutrophication problems such as decreased dissolved oxygen and water quality deterioration. Therefore, effective removal of phosphates from phosphorus-containing water bodies, such as domestic sewage and industrial wastewater, is a crucial step in water environment management and achieving discharge standards.

[0003] Existing wastewater phosphorus removal technologies typically include biological treatment, chemical precipitation, membrane separation, and adsorption. Among these, adsorption removes phosphate ions through interactions between the active sites on the adsorbent surface and phosphate ions (such as electrostatic interactions and ion exchange). The process is relatively simple, and the adsorbent has the potential for regeneration. However, a significant portion of existing phosphorus removal adsorption materials exist in powder or fine particle form, which is easily carried away or lost with the water flow under water treatment operating conditions. This leads to difficulties in recovery, increased operating and maintenance costs, and limits their application in engineering units such as filtration / fixed beds.

[0004] Synthetic fiber materials possess advantages such as good chemical stability and high mechanical strength, making them widely used as filter media or carriers in water treatment. Fiber filter media also offer engineering advantages such as high porosity, low hydraulic resistance, and resistance to leaching. However, common polyester fibers (such as polyethylene terephthalate, PET) have limited polar / charged groups on their surface, making it difficult to form effective adsorption or ion exchange sites for anionic pollutants such as phosphates, resulting in insufficient phosphorus removal functionality. Regarding the surface functionalization of synthetic fibers, existing technologies have included introducing amine or quaternary ammonium groups onto the fibers to form anion exchange fibers. For example, CN114042437A discloses a gas-solid reaction grafting amine group scheme using polyacrylonitrile fibers as a substrate, and CN112593403A discloses a cross-linking grafting and quaternization scheme for preparing strongly basic anion exchange fibers using polyacrylonitrile fibers as a substrate. However, the above-mentioned solutions are mostly based on systems such as polyacrylonitrile, while there are relatively few research and engineering solutions for modified polyester fiber materials for water treatment conditions; at the same time, the lack of reactive sites on the surface of polyester fibers also increases the difficulty of achieving stable functionalization.

[0005] Therefore, there is an urgent need to provide a modified polyester fiber material and its preparation method for water treatment applications. This material should enable the polyester fiber to form anion exchange functional sites (such as quaternary ammonium groups) with permanent positive charges on its surface, while maintaining molding stability and mechanical strength and facilitating recycling in filter / filler units. This would allow for the effective removal of phosphates within typical wastewater pH ranges and phosphorus concentration ranges. Furthermore, the preparation method should be carried out under normal pressure and relatively mild conditions to facilitate engineering scale-up and avoid adverse effects on the performance of the polyester fiber skeleton. Summary of the Invention

[0006] Technical problems to be solved To address the issues of insufficient removal capacity of anions such as phosphates from polyester fibers due to the limited number of reactive sites on their surface and the difficulty in stably constructing positively charged functional groups, which leads to their inadequate removal capacity for anions in the common pH range of water treatment; and the fact that existing phosphorus removal adsorption materials are mostly in powder or fine particle form, easily lost during filtration / filler operation and inconvenient to recycle and regenerate, this invention provides a quaternized ammonium modified polyester fiber material for water treatment and its preparation method. This material enables polyester fibers to acquire anion exchange / electrostatic adsorption sites while maintaining molding stability, and can be used for the adsorption and removal of phosphates in water.

[0007] Technical solution Preparation method This invention provides a method for preparing quaternized ammonium modified polyester fiber material for water treatment. Using polyester fiber material as a matrix, quaternary ammonium groups are introduced onto the fiber surface through grafting, amination, and alkylation quaternization reactions. The method includes the following steps: Grafting reaction steps: The polyester fiber material is placed in a solution containing glycidyl methacrylate (GMA) and the grafting reaction is carried out under water bath conditions of 70-90 ℃, and mechanically stirred at 100-300 rpm for 1-3 h; after the reaction is completed, the fiber material is taken out, extracted with organic solvent by Soxhlet extraction for 4-8 h, and vacuum dried at 60 ℃ for 8 h to obtain the GMA-grafted polyester fiber material. Amination reaction steps: The above-mentioned GMA-grafted polyester fiber material is placed in an organic amine solution and mechanically stirred at 100-300 rpm for 2-4 h under a water bath at 50-90 ℃ for amination reaction; after the reaction, the fiber material is taken out and soaked in methanol for 10-15 min, washed with deionized water and then vacuum dried at 60 ℃ for 8 h to obtain the amination polyester fiber material. Alkylation and quaternization steps: The above-mentioned amination polyester fiber material is placed in a haloalkane solution and mechanically stirred at 100-300 rpm for 4-10 h under water bath conditions of 70-90 ℃ for alkylation reaction; after the reaction, the fiber material is taken out and soaked in methanol for 10-15 min, washed with deionized water and dried under vacuum at 60 ℃ for 8 h to obtain quaternized modified polyester fiber material.

[0008] Furthermore, in some implementations: The polyester fiber material is mainly composed of polyethylene terephthalate; the material has a columnar structure with a pentagonal or circular cross-section, a diameter of 0.5–1 cm, and a length of 1–2 cm. The aforementioned diameter refers to the overall outer diameter of the formed polyester fiber carrier, not the diameter of a single filament. The polyester fiber material is formed by a fiber bundle consisting of several textured, untwisted composite filaments with a single fiber thickness of 3–20 D. In a heating and setting chamber, the bundle passes through a fiber bundle channel tube and is heated by a heat-setting machine. The fiber bundle undergoes heat shrinkage and is then heat-set. After being set through a setting mold tube, the polyester fiber material is obtained, and subsequently cut to a length of 1–2 cm using a cutting machine.

[0009] In the grafting reaction, GMA is soluble in acetone and then diluted with water to form a mixed system, and benzoyl peroxide can be added as an initiator; the Soxhlet extraction solvent can be acetone or methanol.

[0010] In the amination reaction, the organic amine solution can be a triethylenetetramine organic solvent solution; in the quaternization reaction, the haloalkane solution can be a bromohexane methanol solution.

[0011] Quaternized modified polyester fiber materials The quaternized modified polyester fiber material prepared by the above method has quaternary ammonium groups introduced on the fiber surface and has a permanent positive charge. It can combine with phosphate ions in water through ion exchange and electrostatic interaction, thereby achieving phosphate removal. At the same time, the material maintains a columnar structure, which is suitable as a functional fiber carrier in filter / filler units.

[0012] Applications of Quaternized Modified Polyester Fiber Materials This invention also provides the application of the above-mentioned quaternized modified polyester fiber material in the removal of phosphate from domestic sewage or industrial wastewater. In some embodiments, the pH of the water to be treated is 5-8, the phosphorus (P) concentration in the water is 6-48 mg / L, and the dosage of the quaternized modified polyester fiber material is 9-20 g / L.

[0013] Beneficial effects Under the conditions shown in Examples 1-5 and the accompanying drawings, compared with unmodified polyester fiber materials, the present invention has at least the following technical effects: A high removal rate was achieved under certain operating conditions, and the technology was applicable to different initial concentrations: At a dosage of 10 g / L, the phosphate removal rate reached 65%–94% within 5 hours for simulated water samples with initial P concentrations of 6–48 mg / L, with a removal rate of 93.5% at an initial P concentration of 6 mg / L; and the saturated adsorption capacity was 3.65 mg / g (based on P) at an initial P concentration of 48 mg / L (see...). Figure 3 Example 2).

[0014] It exhibits resistance to pH fluctuations under certain operating conditions: At a dosage of 10 g / L, for simulated water samples with an initial P concentration of 50 mg / L and a pH of 3–10, the phosphate removal rate at adsorption equilibrium reaches 80%–92%, corresponding to an equilibrium adsorption capacity of approximately 4.00–4.60 mg / g (based on P) (see...). Figure 4 Example 3).

[0015] It exhibits resistance to interference from inorganic anions under certain operating conditions: At a dosage of 10 g / L, for a simulated water sample with an initial P concentration of 25 mg / L and an initial concentration of coexisting inorganic anions of 50 mg / L, the phosphate removal rate reaches 85%–95% within 5 hours, corresponding to an equilibrium adsorption capacity of approximately 2.13–2.38 mg / g (based on P) (see...). Figure 5 Example 4).

[0016] It exhibits recyclability under certain operating conditions: With a dosage of 10 g / L, for a simulated water sample with an initial P concentration of 45 mg / L, using 0.3 mol / L NaCl solution as the desorbent and a desorption time of 0.5 h, after 10 adsorption-desorption cycles, the phosphate removal rate remained at 84%–89%, corresponding to an equilibrium adsorption capacity of approximately 3.82–4.00 mg / g (based on P) (see...). Figure 6 Example 5).

[0017] The material is stable in form and easy to recycle: the material is a molded polyester fiber carrier that maintains a columnar structure and can be used as a functional carrier in the filter / packing unit. Its form is conducive to solid-liquid separation, recycling and reuse.

[0018] The preparation conditions are mild and the equipment is versatile: the modification reaction can be completed under reflux in a water bath at 50–90 °C and conventional stirring conditions, and is equipped with general equipment such as Soxhlet extraction and vacuum drying, making it feasible for engineering scale-up. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1This is a schematic diagram of the modification process of polyester fiber materials.

[0020] Figure 2 (a) is the XPS full spectrum of the quaternized ammonium modified polyester fiber material. Figure 2 (b) is the N 1s high-resolution spectrum of the quaternized modified polyester fiber material.

[0021] Figure 3 (a) represents the saturated adsorption capacity of phosphate by quaternized modified polyester fiber materials at different initial P concentrations; Figure 3 (b) shows the curve of phosphate removal rate over time under the corresponding conditions.

[0022] Figure 4 The phosphate removal rate of quaternized modified polyester fiber materials under different initial pH values ​​is shown.

[0023] Figure 5 The removal rate of phosphate by quaternized modified polyester fiber materials under the interference of coexisting inorganic anions.

[0024] Figure 6 The adsorption and removal rate of phosphate by quaternized modified polyester fiber material after multiple adsorption-desorption cycles is given. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the following embodiments further illustrate the invention. It should be understood that these embodiments are merely illustrative and do not constitute a limitation on the scope of protection of this invention. Without departing from the spirit of this invention, those skilled in the art can make various modifications or equivalent substitutions to the solutions of this invention, all of which should fall within the scope of protection of this invention.

[0026] Raw materials and testing methods Table 1 Raw Material / Reagent Information Phosphate concentration determination and adsorption calculation Phosphorus concentration determination: The ammonium molybdate spectrophotometric method was used, specifically in accordance with the current national / industry standard GB / T11893-1989; the measurement wavelength was 700 nm, and the instrument model was UV-1800. All phosphorus concentrations mentioned in this manual are expressed as P.

[0027] Adsorption capacity calculation: In a batch adsorption experiment, the adsorption capacity qt (mg / g) at any time t is calculated using the following formula: in, The initial phosphorus concentration (mg / L, as P) Let t be the phosphorus concentration (mg / L, as P), V be the solution volume (L), and m be the mass of adsorbent added (g). Meanwhile, the phosphate removal rate R (%) can be calculated using the following formula: .

[0028] XPS Test Conditions The instrument used for XPS characterization was a Thermo Scientific K-Alpha, and the vacuum level during the test was better than [specific level required]. The excitation source was monochromatic Al Kα rays (hv=1486.6 eV), the operating voltage was 12 kV, and the filament current was 6mA.

[0029] Preparation of Quaternized Modified Polyester Fiber Materials Preprocessing The polyester fiber material is immersed in deionized water for 0.5–2 h, followed by ultrasonic cleaning for 10–30 min to remove surface impurities; after cleaning, it is dried in an oven at 50–60 ℃ to constant weight.

[0030] Step S1: Grafting Weigh 1–5 g of the cleaned and dried polyester fiber material and place it in a reaction vessel. Add a solution containing glycidyl methacrylate (GMA), wherein the mass fraction of the GMA solution is 2%–10%, and add benzoyl peroxide initiator (0.5%–5% by mass of GMA). React under reflux in a water bath at 70–90 °C with mechanical stirring at 100–300 rpm for 1–3 h. After the reaction, remove the fiber material and perform Soxhlet extraction using acetone, methanol, or a combination thereof for 4–8 h to remove unreacted GMA monomers and homopolymers from the fiber surface. Then, vacuum dry at 60 °C for 8 h or until constant weight to obtain GMA-grafted polyester fiber material PETG.

[0031] Step S2: Amination The PETG material obtained in step S1 was placed in an organic amine solution and mechanically stirred at 100–300 rpm for 2–4 h under reflux in a water bath at 50–90 °C to allow the epoxy groups to undergo ring-opening reaction and introduce amine groups. After the reaction was completed, the fiber material was removed, immersed in methanol for 10–15 min, washed with a large amount of deionized water, and then vacuum dried at 60 °C for 8 h or until constant weight to obtain the amination polyester fiber material. .

[0032] Step S3: Quaternization The PETGT material obtained in step S2 was placed in a haloalkane solution and mechanically stirred at 100–300 rpm for 4–10 h under reflux in a water bath at 70–90 °C to induce alkylation of the amino groups and the formation of quaternary ammonium groups. After the reaction was completed, the fiber material was removed, immersed in methanol for 10–15 min, washed with a large amount of deionized water, and then vacuum dried at 60 °C for 8 h or until constant weight to obtain the quaternized ammonium modified polyester fiber material. .

[0033] In some embodiments, the haloalkane can be a bromoalkane with different carbon chain lengths (e.g., C2-C8) to adjust the quaternary ammonium group structure; the quaternization reaction can be repeated once or multiple times to increase the surface quaternary ammonium group density, and the number of multiple quaternization reactions is preferably 2 times. Example 1

[0034] The polyester fiber material was soaked in deionized water at 60 ℃ for 1 h and then ultrasonically cleaned for 15 min. After cleaning, it was dried in an oven at 60 ℃ until constant weight.

[0035] Grafting: Dissolve 7.5 g GMA and 0.15 g benzoyl peroxide in 15 mL acetone, dilute with deionized water to 100 mL and stir well; add 3.0 g of pretreated polyester fiber material, and stir under reflux in an 85 ℃ water bath for 2 h; remove the fiber material and extract with acetone using a Soxhlet extractor for 5 h; after extraction, vacuum dry at 60 ℃ for 8 h to obtain GMA-grafted fiber material. .

[0036] Amination: Mix 50 mL of triethylenetetramine with 50 mL of toluene, add... The material was stirred under reflux in a 70 °C water bath for 4 h; after cooling, it was soaked in methanol for 10 min, washed with deionized water until the filtrate was clear, and then vacuum dried at 60 °C for 8 h to obtain the aminated fiber material. .

[0037] Quaternization: Mix 15 mL of hexane with 30 mL of methanol, and add the above... The material was stirred under reflux in an 80 °C water bath for 6 h; after reaction, it was removed and cooled, then soaked in methanol for 10 min, washed with deionized water until the filtrate was clear, and vacuum dried at 60 °C for 8 h to obtain quaternized ammonium modified polyester fiber material. Sample 1.

[0038] Figure 2 (a) is the XPS full spectrum of the quaternized ammonium modified polyester fiber material. Figure 2(a) It can be seen that, in addition to the strong C 1s (about 285 eV) and O 1s (about 532 eV) peaks, the surface of the quaternized modified polyester fiber material has a characteristic peak belonging to N 1s at a binding energy of about 401 eV and a characteristic peak belonging to Br 3d at a binding energy of about 69 eV. The atomic percentage of N element is 6.8 at%, and the atomic percentage of Br element is 3.0 at%, indicating that the relevant elements after the introduction of nitrogen-containing groups and bromoalkane have existed on the surface of the polyester fiber material.

[0039] Figure 2 (b) is the high-resolution N 1s spectrum of the quaternized ammonium modified polyester fiber material. Figure 2 (b) It can be seen that the N 1s peaks mainly appear at 401.1 eV and 398.8 eV, corresponding to quaternary ammonium nitrogen and amino nitrogen, respectively, with peak area ratios of 56.2% and 43.8%, respectively, indicating that quaternary ammonium groups and amino groups exist on the surface of the modified fiber. Example 2

[0040] Static adsorption experiments were conducted on sample 1 prepared by the method described in Example 1 at different initial phosphorus concentrations. Several 100 mL simulated water samples were prepared, with the initial phosphorus concentration increasing from 6 to 48 mg / L (calculated as P). Example concentrations were 6, 12, 24, 36, and 48 mg / L. The initial pH of each water sample was adjusted to 7.0 ± 0.2 using 0.1 mol / L NaOH (or 0.1 mol / L HCl if necessary). 1.0 g of quaternized modified polyester fiber material sample 1 (addition amount 10 g / L) was added to each water sample. Samples were taken at different time points within 5 h for analysis. The phosphate removal rate versus time curves and saturated adsorption capacity at different initial concentrations were obtained. The results are shown in [Figure 1]. Figure 3 .

[0041] Depend on Figure 3 (a) It can be seen that the saturated adsorption capacity of the quaternized modified polyester fiber material increases with increasing initial phosphorus concentration, and the maximum saturated adsorption capacity is 3.65 mg / g (calculated as P). Figure 3 (b) It can be seen that under the condition of 10 g / L, the phosphate removal rate of water samples with different initial concentrations is in the range of 65% to 94%, of which the removal rate is 93.5% when the initial phosphorus concentration is 6 mg / L (as P). Example 3

[0042] Prepared by the preparation method described in Example 1 Static adsorption tests were conducted on sample 1 at different initial pH values ​​to investigate... Tolerance to different pH levels in water bodies. Several 100 mL simulated water samples with an initial phosphorus concentration of 50 mg / L were prepared. The initial pH of each water sample was adjusted to 3–10 using 0.1 mol / L NaOH or 0.1 mol / L HCl. 1.0 g of Sample 1 (dosage 10 g / L) was added to each water sample. After adsorption at 37 ℃ and 140 rpm for 12 h, the remaining phosphorus concentration was measured to obtain the tolerance under different initial pH conditions. Phosphate removal rate, such as Figure 4 As shown, the corresponding equilibrium adsorption capacity is approximately 4.00–4.60 mg / g (calculated as P). Example 4

[0043] The process was basically the same as in Example 1, except that the mass of benzoyl peroxide was changed to 0.2 g, the amination conditions were changed to stirring in a 50 ℃ water bath for 2 h, and the quaternization conditions were changed to stirring in a 70 ℃ water bath under reflux for 8 h, thus preparing quaternized modified polyester fiber material PETGTC sample 2.

[0044] Add 1.0 g of sample 2 to 100 mL of water. Simulated water samples were prepared with an initial phosphorus (P) concentration of 25 mg / L and containing 50 mg / L of coexisting anions. Before adsorption by shaking, the initial pH of the solution was adjusted to 5.0–6.0 using either 0.1 mol / L NaOH or 0.1 mol / L HCl. After adsorption by shaking at 37 ℃ and 140 rpm for 5 h, the P concentration of the solution was measured to investigate the effect of different coexisting anions on the phosphate removal rate. The coexisting anion salts were... , , And NaCl. The effect of different coexisting anions on phosphate removal rate, such as... Figure 5 As shown.

[0045] In Example 4, each adsorption experiment was performed in parallel three times, and the results shown are the average values; the error bars represent the standard deviation. Example 5

[0046] The preparation of Example 1 Sample 1 was placed in a water sample with an initial phosphorus concentration of 45 mg / L. The initial pH of the solution was adjusted to 5.0–6.0 using 0.1 mol / L NaOH or 0.1 mol / L HCl. After adsorption at 37 ℃ and 140 rpm for 12 h, the sample was removed and placed in a 0.3 mol / L NaCl desorbent solution for desorption at 37 ℃ and 140 rpm for 0.5 h. After desorption, the sample was washed with deionized water until neutral and dried before being used in the next adsorption experiment. The number of cycles was 10; where cycle number 0 represents the first adsorption, and cycles 1–10 represent adsorption experiments after the corresponding number of regeneration cycles. The phosphate removal rate of each cycle is shown in the figure. Figure 6 As shown.

[0047] Summary of Example Data Table 2 Summary of preparation parameters for different samples Table 3 Summary of Adsorption Performance It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing a quaternized modified polyester fiber material for water treatment, characterized in that, The polyester fiber material is a molded polyester fiber carrier, with a columnar structure, a pentagonal or circular cross-section, a diameter of 0.5–1 cm, and a length of 1–2 cm; the preparation method includes the following steps performed in sequence: S1. Grafting: The polyester fiber material is placed in a solution containing glycidyl methacrylate (GMA) and grafted for 1 to 3 hours in a water bath at 70 to 90 °C, with mechanical stirring at 100 to 300 rpm. After the reaction, the fiber material was taken out and subjected to Soxhlet extraction with organic solvent for 4-8 h to remove unreacted monomers and homopolymers. Then, it was vacuum dried at 60 °C to constant weight to obtain GMA-grafted polyester fiber material. S2. Amination: The material obtained in step S1 is placed in an organic amine solution and subjected to an amination reaction at 50–90 °C for 2–4 h, with mechanical stirring at 100–300 rpm. After the reaction, the fiber material was taken out, soaked in methanol and washed with deionized water, and then vacuum dried at 60 °C to constant weight to obtain the amination polyester fiber material. S3. Quaternization: The material obtained in step S2 is placed in a haloalkane solution and alkylated in a water bath at 70-90 °C for 4-10 h, with mechanical stirring at 100-300 rpm to form quaternary ammonium groups from the amino groups; After the reaction, the fiber material was taken out, soaked in methanol and washed with deionized water, and then vacuum dried at 60 °C to constant weight to obtain quaternized ammonium modified polyester fiber material.

2. The preparation method according to claim 1, characterized in that, The polyester fiber material contains more than 90% polyethylene terephthalate (PET) by mass.

3. The preparation method according to claim 1, characterized in that, The mass fraction of the GMA solution in step S1 is 2% to 10%; the organic solvent used for the Soxhlet extraction is acetone, methanol, or a combination thereof.

4. The preparation method according to claim 1 or 3, characterized in that, In step S1, an initiator is further added; the initiator is benzoyl peroxide, and the dosage is 0.5% to 5% based on the mass of GMA.

5. The preparation method according to claim 1, characterized in that, The organic amine mentioned in step S2 is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or polyethyleneimine with a molecular weight of 600 to 3000.

6. The preparation method according to claim 1, characterized in that, The haloalkane mentioned in step S3 is one or more of bromoethane, bromopropane, bromobutane, bromohexane, or bromooctane.

7. A quaternized modified polyester fiber material for water treatment, characterized in that, The material is a molded polyester fiber carrier with a columnar structure, a pentagonal or circular cross-section, a diameter of 0.5 to 1 cm, a length of 1 to 2 cm, and a surface containing quaternary ammonium groups, and is prepared by the method described in any one of claims 1 to 6.

8. The use of the quaternized modified polyester fiber material of claim 7 in the removal of phosphate from water.

9. The application according to claim 8, characterized in that, The pH of the water to be treated is 5-8, the phosphorus (P) concentration in the water is 6-48 mg / L, and the dosage of the quaternized modified polyester fiber material is 9-20 g / L.

10. The application according to claim 8 or 9, characterized in that, The quaternized modified polyester fiber material is regenerated by desorption with sodium chloride solution after adsorption; the concentration of sodium chloride solution is 0.3 mol / L, and the desorption time is 0.5 h.

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