Polymer F-PDA as well as preparation method and application thereof

Abstract

The invention discloses a polymer F-PDA as well as a preparation method and application thereof, the structural formula of the F-PDA is as shown in formula I. The F-PDA is prepared by copolymerizing a water-soluble fluorescent monomer (FM), acrylamide (AM) and dimethyl diallyl ammonium chloride (DMDAAC) through an inverse emulsion polymerization method for the first time. By optimizing process parameters such as the initiator, the emulsifier and the oil-water ratio, the prepared polymer is high in characteristic viscosity and high in dissolution speed. The F-PDA has excellent flocculability and a fluorescence tracing function, the fluorescence intensity and the concentration of the F-PDA have an excellent linear relationship (R is greater than 0.99), and the lower detection limit reaches 1.03 * 10 <-6 > g / L. The system breaks through the bottleneck that a traditional flocculant cannot be accurately monitored in real time, provides key technical support for intelligent feeding and intelligent water quality management based on online monitoring, can be widely applied to sludge dewatering, river dredging and other scenes, and achieves cost reduction and efficiency improvement.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a polymer F-PDA, its preparation method, and its application. Background Technology

[0002] With the accelerating pace of modern industrialization and urbanization, water pollution has become increasingly severe, leading to a dramatic increase in the volume of municipal sludge and river / lake dredging sludge. This sludge has an extremely high water content (typically 95%–99.5%) and is massive in volume, not only occupying significant land resources but also significantly increasing the cost and difficulty of subsequent transportation and disposal. Particularly in river and waterway dredging projects, the traditional method of natural air drying at sludge dumps presents prominent problems such as large land occupation, long dewatering cycles, and a high risk of secondary pollution. Therefore, developing rapid, efficient, and low-consumption sludge dewatering technologies has become an urgent task in the fields of water resource management and environmental protection.

[0003] Sludge and silt have similar compositions, typically containing a large amount of negatively charged organic matter. Their low particle density, loose structure, and high fluidity pose significant challenges to dewatering. Flocculation dewatering is one of the most widely used pretreatment technologies. Among these, the copolymer of dimethyl diallyl ammonium chloride and acrylamide (PDA), a high-performance cationic organic polymeric flocculant, possesses excellent adsorption bridging ability and charge neutralization due to its high-density positive charge on its molecular chain. It also exhibits good water solubility, shear resistance, and stability, making it widely used in the coagulation and dewatering processes of various types of sludge. It effectively disrupts colloidal stability, promotes sludge particle aggregation and growth, thereby improving dewatering performance.

[0004] However, in practical engineering applications, controlling the dosage of PDA flocculants remains a technical challenge. Insufficient dosage leads to poor flocculation and incomplete sludge dewatering; excessive dosage not only wastes reagents and increases treatment costs but may also damage effluent quality due to excessive residual positively charged polymers, causing phenomena such as increased turbidity and COD, known as "over-coagulation." Traditionally, the dosage of flocculants has relied mainly on manual experience or periodic laboratory testing, which cannot respond in real time to dynamic changes in influent water quality and quantity, exhibiting significant lag and making precise and optimized dosage control difficult.

[0005] As the water treatment industry moves towards intelligent and refined processes, online monitoring and automatic control of water treatment chemicals have become an urgent need. Fluorescent tracer technology, with its advantages of high sensitivity, low detection limit, strong anti-interference ability, and real-time online monitoring, offers an innovative solution to this challenge. By introducing groups with specific fluorescent properties into water treatment chemical molecules to create "tracer-type chemicals," the true concentration of the chemical in the system can be accurately and in real-time using an online fluorescence spectrometer. This provides crucial data support for constructing closed-loop automated dosing systems.

[0006] Although fluorescence tracer technology has been used in circulating water treatment agents such as scale inhibitors and corrosion inhibitors, there are no reports, either domestically or internationally, of combining it with cationic flocculants, especially PDA flocculants, to solve the problem of precise agent dosing in sludge dewatering.

[0007] Therefore, developing a cationic flocculant that combines excellent flocculation and dewatering performance with efficient fluorescence tracing function, and developing a matching intelligent monitoring and management system, is of great theoretical significance and broad application prospects for breaking through the bottlenecks of existing sludge dewatering technology, achieving precise dosing of agents, reducing operating costs, improving effluent quality, and promoting the intelligent upgrading of the water treatment industry. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a polymer F-PDA, its preparation method, and its applications. For the first time, a water-soluble fluorescent monomer (FM) is introduced into the PDA polymer chain, successfully synthesizing an F-PDA that combines excellent flocculation performance and fluorescence tracer function. This invention's F-PDA integrates "flocculation function" and "monitoring and tracer function," not only exhibiting superior performance but also solving the long-standing problem of precise dosing control in the water treatment industry, laying a core technological foundation for the ultimate realization of intelligent water treatment.

[0009] This invention is achieved through the following technical solution:

[0010] A polymer F-PDA, the structural formula of which is shown in Formula I:

[0011]

[0012] Formula I;

[0013] In Formula I, the molar ratio of m, n, and k is (7~9):(1.5~2.5):(0.0004~0.0006).

[0014] Preferably, in Formula I, the molar ratio of m, n, and k is 8:2:0.0005.

[0015] Preferably, the concentration of the F-PDA is linearly related to its fluorescence intensity, with a linear correlation coefficient R > 0.95.

[0016] The preparation method of the above-mentioned polymer F-PDA includes the following steps:

[0017] Step 1) Weigh out the monomers acrylamide and dimethyl diallyl ammonium chloride, add the fluorescent monomer 4-methoxy-N-(2-N',N'-dimethylaminoethyl)naphthalenedicarboximide allyl ammonium chloride, and then add distilled water to prepare an aqueous solution;

[0018] Step 2) Weigh sorbitan monooleate and polyethylene glycol octylphenyl ether as composite emulsifiers, dissolve them in kerosene, and prepare an oil phase solution;

[0019] Step 3) Mix the aqueous solution obtained in step 1) with the oil solution obtained in step 2), add EDTA solution and emulsify, remove oxygen and then add an initiator to carry out the reaction;

[0020] Step 4) After stopping the reaction, filter and dry to obtain the product.

[0021] Preferably, in step 1), the molar ratio of the monomer acrylamide to the monomer dimethyl diallyl ammonium chloride is (3~5):1; the amount of the fluorescent monomer 4-methoxy-N-(2-N',N'-dimethylaminoethyl)naphthalenedicarboximide allyl ammonium chloride is 0.15%~0.25% of the total mass of the monomer acrylamide and the monomer dimethyl diallyl ammonium chloride.

[0022] Step 2) The HLB value of the composite emulsifier is 5.0~5.5; the concentration of the composite emulsifier in the oil phase solution is 7.5%~9.0%.

[0023] Preferably, in step 1), the molar ratio of the monomer acrylamide to the monomer dimethyl diallyl ammonium chloride is 4:1; the amount of the fluorescent monomer 4-methoxy-N-(2-N',N'-dimethylaminoethyl)naphthalenedicarboximide allyl ammonium chloride is 0.2% of the total mass of the monomer acrylamide and the monomer dimethyl diallyl ammonium chloride.

[0024] Step 2) The HLB value of the composite emulsifier is 5.2; the concentration of the composite emulsifier in the oil phase solution is 8.5%.

[0025] Preferably, in step 3), the volume ratio of the aqueous phase solution to the oil phase solution is (0.8~1.2):1;

[0026] The amount of EDTA solution used is (1.0~2.0)×10. -6 g / mL;

[0027] The initiator is a mixed solution of water-soluble azo compound V-50 and sodium bisulfite; the amount of the initiator is 1.05% to 1.15% of the total mass of the three monomers.

[0028] Preferably, in step 3), the volume ratio of the aqueous solution to the oil solution is 1:1;

[0029] The amount of EDTA solution used was 1.56 × 10⁻⁶. -6 g / mL;

[0030] The amount of the initiator is 1.1% of the total mass of the three monomers.

[0031] The application of the above-mentioned polymer F-PDA, or the polymer F-PDA prepared by the above method, in flocculants.

[0032] The above-mentioned polymer F-PDA, or polymer F-PDA prepared by the above method, is used as a flocculant with fluorescent tracer function in water quality management.

[0033] The beneficial effects of this invention are as follows:

[0034] (1) This invention is the first to introduce water-soluble fluorescent monomers (FM) into the PDA polymer chain, successfully synthesizing F-PDA with both excellent flocculation performance and fluorescence tracer function. The fluorescence signal released by this flocculant in water has a highly accurate linear relationship with its mass concentration (linear correlation coefficient R). 2 >0.9999), detection limit as low as 10 -6 The g / L level is a key feature that enables real-time and accurate measurement of the actual residual concentration of F-PDA in the water treatment system using an online fluorescence monitor. This completely changes the traditional extensive dosing method that relies on manual experience and lags behind laboratory testing. Operators can dynamically adjust the dosing pump based on real-time concentration data to ensure that the reagent concentration is always within the optimal treatment range. This fundamentally avoids poor treatment results due to insufficient dosing, or waste of reagents and deterioration of effluent quality (such as increased COD and decreased light transmittance) due to excessive dosing.

[0035] (2) This invention successfully prepared an F-PDA copolymer with a characteristic viscosity of approximately 6.30 dL / g by optimizing the reverse emulsion polymerization process parameters (such as the initiation system, HLB value and dosage of emulsifier, EDTA complexing agent, oil-water ratio, etc.). The high molecular weight means longer molecular chains and stronger adsorption bridging ability, thereby forming denser and larger flocs, significantly improving the dewatering speed of sludge and the solids content of sludge cake. At the same time, the reverse emulsion polymerization process endows the product with the characteristic of rapid dissolution, which can be quickly dispersed and dissolved upon contact with water, greatly shortening the preparation and onset time of the reagent, improving the treatment efficiency, and is especially suitable for automated continuous dosing systems.

[0036] (3) The F-PDA of this invention, as a "sensory" intelligent chemical, can have its fluorescence signal easily captured and converted into a digital signal by online analytical instruments. This provides a solid material foundation for developing an intelligent water quality management system that integrates online monitoring, remote data transmission, intelligent analysis, and automatic feedback control. The system can automatically calculate and adjust the dosage based on the influent flow, water quality changes, and the real-time concentration of F-PDA, achieving precise dosing, energy saving and consumption reduction, and fully unmanned intelligent management. It is a key innovation for the water treatment industry's transformation towards digitalization and intelligence.

[0037] (4) This invention integrates fluorescence tracer technology with the molecular design of high-performance cationic flocculants and reverse emulsion polymerization process across fields, resulting in a novel technical concept. F-PDA can be widely used in various fields such as municipal sewage treatment, industrial wastewater treatment, and river and lake sludge dewatering, demonstrating good versatility. This technology not only improves the performance of individual products but also creates a systematic solution of "reagent + monitoring + intelligent control," possessing extremely high market application value and promotion prospects. Attached Figure Description

[0038] Figure 1 The infrared spectrum of polymer F-PDA in Example 1;

[0039] Figure 2 The fluorescence properties of polymer F-PDA in Example 1 are shown in Figure 1: A is the fluorescence spectrum; B is the standard curve. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0041] Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art, and the experimental methods without specific conditions are all conventional methods in the art.

[0042] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0043] Example 1

[0044] A method for preparing polymer F-PDA, the synthesis principle of which is to obtain copolymer F-PDA by free radical polymerization of three water-soluble monomers, the structural formula of which is shown in Formula I:

[0045]

[0046] Formula I

[0047] The reaction equation is shown in Equation II:

[0048]

[0049] Formula II

[0050] In Equations I and II, the molar ratio of m, n, and k is 8:2:0.0005.

[0051] A fluorescently labeled cationic copolymer FP (DMDAAC-AM) (F-PDA) with a cationicity of 20% was prepared using reverse emulsion polymerization technology, with sorbitan monooleate Span-80 and polyethylene glycol octylphenyl ether Op-10 as composite emulsifiers, kerosene as the dispersion medium, water-soluble azo compound V-50 and sodium bisulfite (NaHSO3) as composite initiators, and dimethyl diallyl ammonium chloride (DMDAAC), acrylamide (AM), and the water-soluble fluorescent monomer 4-methoxy-N-(2-N',N'-dimethylaminoethyl)naphthalenedicarboximide allyl ammonium chloride (FM) as raw materials. The specific steps are as follows:

[0052] (1) Weigh a certain amount of AM and DMDAAC according to a molar ratio of 8:2, add an appropriate amount of fluorescent monomer FM (its mass is 0.2% of the total mass of AM and DMDAAC monomers), and then add an appropriate amount of distilled water to prepare an aqueous solution (the total concentration of the three monomers is 40%).

[0053] (2) Weigh out appropriate amounts of Span-80 and Op-10 as composite emulsifiers according to an HLB value of 5.2, dissolve them in an appropriate amount of kerosene, and prepare an oil phase solution (the concentration of composite emulsifier is 8.5%).

[0054] (3) Mix the aqueous phase solution and the oil phase solution prepared above at a volume ratio of 1:1, and add 1.56×10 -6 After emulsifying the g / mLEDTA solution, the emulsion was poured into a four-necked flask equipped with a thermometer, stirrer, constant pressure funnel, and condenser. The flask was placed in a constant temperature water bath, and N2 was bubbled through it for 20 min with stirring to remove oxygen. Then, a composite initiator (V-50 + NaHSO3) was added dropwise. The amount of the composite initiator was 1.1% of the total mass of the three monomers. The reaction was carried out at 30℃ for 4 h.

[0055] (4) After stopping the reaction, precipitate with methanol, filter, wash the filter cake with acetone, filter the product and dry it at a constant temperature to obtain the powdered product F-PDA.

[0056] like Figure 1 The image shows the infrared spectrum of the F-PDA. As can be seen from the image, the positions of the characteristic peaks are: 3418.35 cm⁻¹. -1 The absorption peak for the -NH2 stretching vibration is located at 2931.56 cm⁻¹. -1The peak at 2857.46 cm⁻¹ represents the characteristic absorption peak of the antisymmetric stretching vibration of -CH₃. -1 The characteristic absorption peak for the symmetric stretching vibration of -CH2 is located at 1666.59 cm⁻¹. -1 The peak at 964.36 cm⁻¹ represents the stretching vibration absorption peak of the C=O group in the amide group. -1 The characteristic peak at 2780 cm⁻¹ is for the =CH group; -1 There is a weak absorption peak on the left and right, which is a characteristic absorption peak of quaternary ammonium salt; due to the strong water absorption of the copolymer F-PDA, the absorption peak is at >3000 cm⁻¹. -1 A broad absorption peak for the stretching vibration of the -OH group appeared at 1430 cm⁻¹; another peak appeared at 1430 cm⁻¹. -1 ~1600 cm -1 The presence of stretching absorption peaks in the vicinity of five- or six-membered rings with CC and CN linkages indicates that copolymerization has occurred.

[0057] Weigh 0.1 g of F-PDA (FM content 0.2%), dissolve it in distilled water to prepare a 100 mL solution, and dilute an appropriate amount to a certain concentration. Measure the excitation and emission wavelengths using a 970CRT fluorescence spectrophotometer. Prepare a series of solutions with different concentrations and determine the relationship between product fluorescence intensity and concentration. The measurement parameters were: excitation slit width 5 nm; emission slit width 5 nm; and fast scan speed.

[0058] The fluorescence performance test results of F-PDA are as follows: Figure 2 As shown, by Figure 2 As shown in section A, this copolymer F-PDA exhibits excellent fluorescence properties, with an excitation wavelength of 381 nm and an emission wavelength of 462 nm. For example... Figure 2 As shown in Figure B, the concentration (c) of copolymer F-PDA and its fluorescence intensity (y) exhibit a good linear relationship, with the linear equation being y = 4.964 + 48.736 × 10⁻⁶. -5 c, Linear correlation coefficient (R²) 2 The detection limit is 0.99996. Therefore, routine quantitative fluorescence analysis can be performed. Based on the limit of detection formula (limit of detection = 3σ / k, where σ is the variance and k is the slope), the limit of detection for copolymer F-PDA can be calculated to be 1.03 × 10⁻⁶. -6 g / L.

[0059] Example 2: Effect of initiator dosage on product performance

[0060] The copolymer F-PDA was prepared using the method described in Example 1, with the difference being that the amount of composite initiator (i.e., the percentage of the total mass of the three monomers) was changed to explore the influence of the amount of initiator on the copolymer properties. The results are shown in Table 1.

[0061] Determination of the intrinsic viscosity (η) of the copolymer: The intrinsic viscosity of F-PDA was determined in accordance with GB12005.1-89, and the determination conditions were 30℃ and 1.0 mol / L sodium chloride aqueous solution.

[0062] Product water solubility test: Add 0.3 g of the product to a 100 mL beaker, set the magnetic stirrer to 25℃, add 100 mL of distilled water, and stir with the magnetic stirrer. Start timing from the addition of distilled water until the product is completely dissolved. Record the product dissolution time (in minutes).

[0063] Table 1 Effect of initiator dosage on product properties

[0064]

[0065] As shown in Table 1, when the initiator concentration is less than 1.1%, the characteristic viscosity of the product increases with increasing initiator concentration. However, when the initiator concentration exceeds 1.1%, the characteristic viscosity of the product decreases with increasing initiator concentration. This is mainly because when the initiator concentration is low, the concentration of free radicals that can initiate monomer polymerization is low under the condition of a certain polymerization time, resulting in a high monomer residue and a low characteristic viscosity of the copolymer. Conversely, when the initiator concentration is too high, the number of free radicals generated during polymerization increases, leading to an increase in the number of free radicals per unit volume and a decrease in the characteristic viscosity of the resulting copolymer.

[0066] The experimental results of this embodiment show that when the amount of initiator is 1.1% of the total mass of the three monomers, the resulting copolymer has the highest characteristic viscosity.

[0067] Example 3 Effect of emulsifier dosage on product properties

[0068] The copolymer F-PDA was prepared using the method described in Example 1, except that the amount of composite emulsifier (i.e., its concentration percentage in the oil phase solution) was varied to investigate the effect of emulsifier dosage on product properties. The results are shown in Table 2. The characteristic viscosity (η) of the copolymer and the water solubility of the product were determined using the same methods as in Example 2.

[0069] Table 2 Effect of emulsifier dosage on product properties

[0070]

[0071] Table 2 shows that when the emulsifier dosage is less than 8.5%, the characteristic viscosity of the product gradually increases with increasing emulsifier dosage. When the dosage is greater than 8.5%, the characteristic viscosity of the product decreases with increasing dosage. When the emulsifier dosage is low, the incompletely emulsified system is relatively unstable, and the polymerization reaction mainly occurs in the monomer droplets, resulting in a lower relative molecular weight of the polymer. When the emulsifier dosage exceeds a certain value (8.5%), the number of micelles in the system further increases with increasing dosage. With a fixed monomer dosage, the number of monomers evenly distributed in each micelle is relatively reduced, making it more difficult to polymerize into large molecules, thus lowering the characteristic viscosity value.

[0072] The experimental results of this embodiment show that when the concentration of emulsifier in the oil phase solution is 8.5%, the characteristic viscosity value of the copolymer is relatively large.

[0073] Example 4: Effect of emulsifier HLB value on product properties

[0074] The copolymer F-PDA was prepared using the method described in Example 1, with the difference being that the HLB value of the composite emulsifier was changed to investigate the effect of different HLB values ​​on the product properties. The results are shown in Table 3. The characteristic viscosity (η) of the copolymer and the water solubility of the product were determined using the same methods as in Example 2.

[0075] Table 3. Effect of emulsifier HLB value on product properties

[0076]

[0077] As shown in Table 3, when the HLB value of the emulsifier is less than 5.2, the characteristic viscosity of the product gradually increases with the increase of the HLB value of the emulsifier. When the HLB value is greater than 5.2, the characteristic viscosity of the product shows a decreasing trend with the increase of the HLB value. This is because when the HLB value is less than 5.2, the stability of the latex particles increases with the increase of the HLB value of the emulsifier, the reaction is stable, the number of latex particles increases, and the characteristic viscosity of the copolymer increases. When the HLB value exceeds 5.2, the system exhibits a certain degree of sticking to the reactor during the effluent stage, and the characteristic viscosity of the copolymer also decreases accordingly.

[0078] The experimental results of this embodiment show that the optimal HLB value for the emulsifier is around 5.2.

[0079] Example 5: Effect of EDTA dosage on product performance

[0080] The copolymer F-PDA was prepared using the method described in Example 1, except that the amount of EDTA was varied to investigate its effect on the copolymer's properties. The results are shown in Table 4. The determination methods for the copolymer's characteristic viscosity (η) and the product's water solubility were the same as in Example 2.

[0081] Table 4 Effect of EDTA dosage on product performance

[0082]

[0083] The addition of EDTA can complex polyvalent metal ion impurities in the monomer, reducing the occurrence of side reactions. Table 4 shows that when the amount of EDTA is 1.56 × 10⁻⁶... -6 At a concentration of g / mL, the copolymer exhibits the highest characteristic viscosity. Furthermore, experimental observations show that the reaction solution is stable and does not stick to the vessel at this concentration. Extraction with ethanol and acetone yields a very fine powder with a high yield. As the amount of EDTA increases to 2.34 × 10⁻⁶ g / mL, the characteristic viscosity of the copolymer increases further. -6 g / mL and 3.12×10 -6 At a concentration of g / mL, the metal ions in the emulsion are almost completely complexed. Excess EDTA will consume some of the initiator, causing a decrease in the characteristic viscosity of the product. In addition, increasing the amount of EDTA will increase side reactions such as chain transfer, thereby reducing the relative molecular mass of the copolymer and affecting the characteristic viscosity of the copolymer.

[0084] The experimental results of this embodiment show that the optimal dosage of EDTA is 1.56 × 10⁻⁶. -6 g / mL.

[0085] Example 6: Effect of oil-water volume ratio on product performance

[0086] The copolymer F-PDA was prepared using the method described in Example 1, with the difference that the volume ratio of the aqueous solution to the oil solution was changed to investigate the effect of the oil-water volume ratio on the product properties. The results are shown in Table 5. The characteristic viscosity (η) of the copolymer and the water solubility of the product were determined using the same methods as in Example 2.

[0087] Table 5. Effect of oil-water volume ratio on product properties

[0088]

[0089] Table 5 shows that when the oil-to-water volume ratio is less than 1:1, the characteristic viscosity of the product gradually increases with increasing oil-to-water volume ratio. When the oil-to-water volume ratio is greater than 1:1, the characteristic viscosity of the product decreases with increasing oil-to-water volume ratio. This is mainly because the oil phase, as the continuous phase, plays a role in dispersing droplets and also affects the heat dissipation of the system, the polymerization process, the size, morphology, and stability of emulsion particles. When the oil-to-water volume ratio is low, the dispersibility is better and the emulsion stability is better with increasing oil-to-water volume ratio, which is conducive to the polymerization reaction. When the oil-to-water volume ratio increases further, the oil phase dilutes the monomer, the monomer concentration in the system decreases, hindering the polymerization reaction and making it unfavorable for the formation of high molecular weight polymers.

[0090] The experimental results of this embodiment show that the characteristic viscosity of the copolymer is relatively large when the oil-water volume ratio is 1:1.

[0091] The embodiments described above are only some, not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. The scope of protection of the present invention is determined by the scope claimed in the claims. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A polymer F-PDA, characterized in that, The structural formula of the F-PDA is shown in Formula I: Formula I; In Formula I, the molar ratio of m, n, and k is (7~9):(1.5~2.5):(0.0004~0.0006).

2. The polymer F-PDA according to claim 1, characterized in that, In Formula I, the molar ratio of m, n, and k is 8:2:0.0005.

3. The polymer F-PDA according to claim 1, characterized in that, The concentration of F-PDA is linearly related to its fluorescence intensity, with a linear correlation coefficient R > 0.

95.

4. A method for preparing a polymer F-PDA according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1) Weigh out the monomers acrylamide and dimethyl diallyl ammonium chloride, add the fluorescent monomer 4-methoxy-N-(2-N',N'-dimethylaminoethyl)naphthalenedicarboximide allyl ammonium chloride, and then add distilled water to prepare an aqueous solution; Step 2) Weigh sorbitan monooleate and polyethylene glycol octylphenyl ether as composite emulsifiers, dissolve them in kerosene, and prepare an oil phase solution; Step 3) Mix the aqueous solution obtained in step 1) with the oil solution obtained in step 2), add EDTA solution and emulsify, remove oxygen and then add an initiator to carry out the reaction; Step 4) After stopping the reaction, filter and dry to obtain the product.

5. The method for preparing polymer F-PDA according to claim 4, characterized in that, Step 1) The molar ratio of the monomer acrylamide to the monomer dimethyl diallyl ammonium chloride is (3~5):1; the amount of the fluorescent monomer 4-methoxy-N-(2-N',N'-dimethylaminoethyl)naphthalenedicarboximide allyl ammonium chloride is 0.15%~0.25% of the total mass of the monomer acrylamide and the monomer dimethyl diallyl ammonium chloride. Step 2) The HLB value of the composite emulsifier is 5.0~5.5; the concentration of the composite emulsifier in the oil phase solution is 7.5%~9.0%.

6. The method for preparing polymer F-PDA according to claim 5, characterized in that, Step 1) The molar ratio of the monomer acrylamide to the monomer dimethyl diallyl ammonium chloride is 4:1; the amount of the fluorescent monomer 4-methoxy-N-(2-N',N'-dimethylaminoethyl)naphthalenedicarboximide allyl ammonium chloride is 0.2% of the total mass of the monomers acrylamide and dimethyl diallyl ammonium chloride. Step 2) The HLB value of the composite emulsifier is 5.2; the concentration of the composite emulsifier in the oil phase solution is 8.5%.

7. The method for preparing polymer F-PDA according to claim 4, characterized in that, In step 3), the volume ratio of the aqueous phase solution to the oil phase solution is (0.8~1.2):1; The amount of EDTA solution used is (1.0~2.0)×10. -6 g / mL; The initiator is a mixed solution of water-soluble azo compound V-50 and sodium bisulfite; the amount of the initiator is 1.05% to 1.15% of the total mass of the three monomers.

8. The method for preparing polymer F-PDA according to claim 7, characterized in that, In step 3), the volume ratio of the aqueous solution to the oil solution is 1:1; The amount of EDTA solution used was 1.56 × 10⁻⁶. -6 g / mL; The amount of the initiator is 1.1% of the total mass of the three monomers.

9. The use of polymer F-PDA as described in any one of claims 1-3, or polymer F-PDA prepared by any one of claims 4-8, in flocculants.

10. The application of the polymer F-PDA as described in any one of claims 1-3, or the polymer F-PDA prepared by the preparation method as described in any one of claims 4-8, as a flocculant with fluorescent tracer function in water quality management.

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