Stable formula for preparing anionic polyacrylamide by thiol-ene click chemical synthesis method

Abstract

The invention discloses a method for preparing high-stability anionic polyacrylamide based on thiol-ene click chemistry. The core of the method is to construct an omnibearing stable system of a polymer from three dimensions through a click chemical reaction: the structure is stable: a topological chain structure with a space charge shielding effect is formed through accurate arrangement of monomers, so that a molecular skeleton and an active group keep long-acting stability. And the conformation is stable: the rigid-flexible adjustable chain segment design forms an internal microphase separation structure, so that the polymer can maintain the stretched and stable hydration conformation in various aqueous solutions, and the performance is consistent. And the process is stable: the reaction mechanism of ion complexing and click addition realizes the gentle release of polymerization heat, so that the synthesis process has high tolerance to parameter fluctuation. According to the invention, the problem of performance degradation caused by disordered structure and sensitive process of a traditional product is systematically solved, and a reliable solution is provided for the application field with strict requirements on stability.

Description

Technical Field

[0001] This invention belongs to the technical field of wastewater treatment and polymeric flocculants, specifically relating to a stable formulation for preparing anionic polyacrylamide using a thiol-olefin click chemical synthesis method. Background Technology

[0002] Polyacrylamide (PAM) is an important water-soluble polymer widely used in oil extraction, wastewater treatment, papermaking, mining and metallurgy. However, two key technical challenges have long existed in its synthesis and application: (1) Unstable polymerization process: The free radical polymerization of acrylamide (AM) is exothermic and prone to branching and crosslinking side reactions. Traditional methods use chain transfer agents such as isopropanol, dodecyl mercaptan, and mercaptoacetic acid to control molecular weight and prevent "explosive polymerization" and gelation. However, these traditional chain transfer agents have obvious defects, such as single function, only playing the role of terminating chain growth and regulating molecular weight, and cannot bring any performance gain to the final product; in addition, there are potential side effects, some hydrophobic chain transfer agents such as dodecyl mercaptan may affect the water solubility of the product, and the terminal groups introduced by them may even become the weak point of long-term chemical stability of the product; poor process controllability, some chain transfer agents have poor dispersion and stability in the aqueous system, resulting in unsatisfactory repeatability and controllability of polymerization reactions between different batches. (2) Poor salt resistance of the product: The amide group (-CONH2) on the molecular chain of conventional polyacrylamide has weak salt resistance, especially when it contains high-valence metal ions (such as Ca). 2+ Mg 2+ In hard water or seawater, molecular chains are prone to coiling and conformational contraction, leading to a sharp decrease in solution viscosity and a significant deterioration in flocculation or thickening effects, which greatly limits its application in high-salt environments.

[0003] To address these issues, various methods were attempted, such as copolymerization with salt-resistant monomers like 2-acrylamido-2-methylpropanesulfonic acid (AMPS). However, the polymerization activity of the salt-resistant monomers is complex to match with that of acrylamide, leading to instability during the introduction process. Alternatively, chemical modifications such as sulfonation methylation of the synthesized PAM could be performed, but this process is cumbersome, requires harsh reaction conditions, and is prone to polymer degradation.

[0004] Therefore, there is an urgent need in this field for a simplified, efficient and stable synthesis technology that can simultaneously achieve stable control of the polymerization process and improve the inherent salt resistance of the product. Summary of the Invention

[0005] One object of the present invention is to provide a polyacrylamide that can improve polymerization stability and salt resistance.

[0006] Another object of the present invention is to provide a method for preparing the polyacrylamide.

[0007] Another object of the present invention is to provide the application of the polyacrylamide.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A stable formulation for preparing anionic polyacrylamide by a thiol-olefin click chemistry synthesis method comprises, by weight, 125-130 parts of acrylamide, 12-14 parts of acrylate-2-acrylamido-2-methylpropanesulfonic acid, 2.5-3.0 parts of composite stabilizer, 10-12 parts of urea, and 340-350 parts of deionized water; it also includes 100 ppm of EDTA-4Na, 10 ppm of azobisisobutyrazoline hydrochloride, and 4 ppm of redox initiator.

[0009] Preferably, the anionic polyacrylamide comprises, by weight, 125 parts acrylamide, 12 parts acrylic acid-2-acrylamide-2-methylpropanesulfonic acid, 2.5 parts composite stabilizer, 10 parts urea, and 350 parts deionized water; it also comprises 100 ppm EDTA-4Na, 10 ppm azobisisobutyrazoline hydrochloride, and 4 ppm redox initiator.

[0010] Preferably, the anionic polyacrylamide comprises, by weight, 130 parts acrylamide, 14 parts acrylic acid-2-acrylamide-2-methylpropanesulfonic acid, 3.0 parts composite stabilizer, 12 parts urea, and 340 parts deionized water; it also comprises 100 ppm EDTA-4Na, 10 ppm azobisisobutyrazoline hydrochloride, and 4 ppm redox initiator.

[0011] Preferably, the composite stabilizer is a mixture of ammonium sulfate and sodium 3-mercaptopropanesulfonate in a mass ratio of 1:1.

[0012] Preferably, the redox initiator is tert-butanol hydrogen peroxide and ferrous ammonium sulfate.

[0013] More preferably, the mass ratio of tert-butanol hydrogen peroxide to ferrous ammonium sulfate is 1:1.

[0014] The present invention also provides a method for preparing the anionic polyacrylamide, which includes the following steps: S1. Dissolve acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, composite stabilizer, and urea in deionized water, stir until completely dissolved, and adjust the pH of the solution to 3.7-4.0. S2. Freeze the solution to -3°C and purge it with nitrogen gas to remove oxygen; S3, add EDTA-4Na and azobisisobutyrazoline hydrochloride in sequence; S4. Add a redox initiator at 0.5℃ to initiate the polymerization reaction; S5. Polymerize for 6-8 hours until gel state is reached to obtain a colloid; S6. Hydrolyze with NaOH, granulate, dry, grind, and sieve to obtain the anionic polyacrylamide.

[0015] Preferably, in step S2, the nitrogen gas is introduced for 30 minutes.

[0016] Preferably, in step S6, the mass concentration of NaOH is 20-30%.

[0017] Preferably, the hydrolysis time is 30-60 minutes.

[0018] The present invention also provides the application of the anionic polyacrylamide in wastewater treatment.

[0019] The present invention has the following beneficial effects: (1) Promoting “stable synthesis” during polymerization. This invention employs a thiol-olefin click chemistry reaction: PAM radicals transfer to HS-CH2CH2CH2SO3Na to form RS•, which then adds to the C=C bond of AM, grafting -CH2CH2CH2SO3- groups and restarting polymerization. AA-AMPS stabilizes the polymerization reaction and provides a polymerization initiation point, which is innovative compared to monomer addition reactions. The thiol group in the thiol compound of the composite stabilizer is a highly efficient chain transfer group, which can precisely control the molecular weight and distribution of polyacrylamide, effectively suppressing branching and crosslinking side reactions during the reaction process, fundamentally avoiding the occurrence of “explosive polymerization” and gelation, and ensuring the stability, controllability and repeatability of the polymerization reaction. The composite stabilizer is a water-soluble salt with excellent compatibility with the acrylamide aqueous solution system and uniform distribution, avoiding the uneven dispersion problem that may be caused by traditional hydrophobic chain transfer agents, further improving the stability of the synthesis process.

[0020] (2) Improve the performance of PAM products. The composite stabilizer not only undergoes chain transfer, but also, through the "thiol-ene" click chemistry mechanism, firmly grafts the sulfonic acid groups in the molecule onto the polyacrylamide molecular chain in the form of covalent bonds. The sulfonic acid groups have extremely strong hydration capacity and charge repulsion effect. In high-salt or hard water environments, the molecular chains are not easily coiled and can remain stretched for a long time, thereby significantly improving the stability of solution viscosity and the durability of flocculation effect.

[0021] (3) Improve process stability. Thiols achieve precise chain transfer through the thiol-alkene reaction, preventing runaway reactions. Ammonium sulfate ensures uniform dispersion.

[0022] (4) The sulfonic acid grafting is achieved through thioether bonds, which enhances the hydration / repulsion effect in the salt water environment and is superior to the traditional method.

[0023] (5) It is an aqueous system with low toxicity; it can be mass-produced; it has few by-products and is environmentally friendly. Detailed Implementation

[0024] To facilitate understanding of the present invention, a more complete description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0026] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0027] Composite stabilizer: ammonium sulfate and sodium 3-mercaptopropanesulfonate (1:1 mass ratio).

[0028] Example 1 Dissolve 125g acrylamide, 12g acrylate-2-acrylamide-2-methylpropanesulfonic acid, 2.5g composite stabilizer, and 10g urea in 350g deionized water and stir until completely dissolved. Adjust the pH of the solution to 3.7, freeze the solution to -3°C, and then place it in an insulated container and purge with nitrogen for at least 30 minutes to remove oxygen. Then add 100ppm EDTA-4Na and 10ppm azobisisobutyrazoline hydrochloride (VA-044) to the system. At 0.5°C, add 4ppm tert-butanol hydrogen peroxide and ferrous ammonium sulfate (tert-butanol hydrogen peroxide:ferrous ammonium sulfate = 1:1 (mass ratio) to initiate the polymerization reaction. The polymerization reaction proceeds stably for 6 hours.

[0029] After the reaction is complete, the mixture reaches a gel state, yielding a colloid.

[0030] Then, NaOH (20% mass concentration) was added for hydrolysis for 60 minutes. After hydrolysis, the product was granulated, dried (60℃), ground and pulverized, and sieved (20 mesh) to obtain the PAM product.

[0031] Example 2 Dissolve 130g acrylamide, 14g acrylate-2-acrylamide-2-methylpropanesulfonic acid, 3.0g composite stabilizer, and 12g urea in 340g deionized water and stir until completely dissolved. Adjust the pH of the solution to 4.0, freeze the solution to -3°C, and then place it in an insulated container and purge with nitrogen for at least 30 minutes to remove oxygen. Then, add 100ppm EDTA-4Na and 10ppm azobisisobutyrazoline hydrochloride (VA-044) sequentially to the system. At 0.5°C, add 4ppm tert-butanol hydrogen peroxide and ferrous ammonium sulfate (tert-butanol hydrogen peroxide:ferrous ammonium sulfate = 1:1 (mass ratio) to initiate the polymerization reaction. The polymerization reaction proceeds stably for 8 hours.

[0032] After the reaction is complete, the mixture reaches a gel state, yielding a colloid.

[0033] Then, NaOH (30% mass concentration) was added for hydrolysis for 30 minutes. After hydrolysis, the product was granulated, dried (60℃), ground and pulverized, and sieved (20 mesh) to obtain the PAM product.

[0034] Comparative Example Dissolve 150g acrylamide, 15g 2-acrylamide-2-methylpropanesulfonic acid, and 1.0g isopropanol in 334g deionized water and stir until completely dissolved. Adjust the pH of the solution to 6.5-7.5 and purge with nitrogen to remove oxygen (at room temperature). Add 100ppm EDTA-2Na, 4ppm ammonium persulfate, and 4ppm sodium bisulfite to initiate the polymerization reaction (at room temperature).

[0035] After the reaction is complete, a colloid is obtained, which is then granulated, dried, pulverized, and sieved to obtain the PAM product.

[0036] Performance testing Take 500 mL of actual high-salinity wastewater from a chemical industrial park (TDS = 18 × 10⁻⁶). 3 mg / L, Ca 2+ = 2800 mg / L, SS = 650 mg / L, pH = 7.8) were placed in a graduated cylinder. 3 mL of PAM solution (mass concentration 1‰) was added, and the mixture was slowly inverted 5 times to mix. The mixture was then allowed to stand and observed.

[0037] Record the average particle size (D50) of the flocs, the settling velocity, and the removal rate of SS (suspended solids).

[0038] The test results are shown in Table 1.

[0039]

[0040] As can be seen from Table 1, the PAM in Examples 1-2 of this invention has a significantly better effect on treating high-salt wastewater than the comparative example.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A stable formulation for preparing anionic polyacrylamide using a thiol-olefin click chemistry method, characterized in that, The product comprises, by weight, 125-130 parts acrylamide, 12-14 parts acrylic acid-2-acrylamide-2-methylpropanesulfonic acid, 2.5-3.0 parts composite stabilizer, 10-12 parts urea, and 340-350 parts deionized water; it also includes 100 ppm EDTA-4Na, 10 ppm azobisisobutyrazoline hydrochloride, and 4 ppm redox initiator.

2. The stable formulation of anionic polyacrylamide according to claim 1, characterized in that, The anionic polyacrylamide comprises, by weight, 125 parts acrylamide, 12 parts acrylic acid-2-acrylamide-2-methylpropanesulfonic acid, 2.5 parts composite stabilizer, 10 parts urea, and 350 parts deionized water; it also includes 100 ppm EDTA-4Na, 10 ppm azobisisobutyrazoline hydrochloride, and 4 ppm redox initiator.

3. The stable formulation of anionic polyacrylamide according to claim 1, characterized in that, The anionic polyacrylamide comprises, by weight, 130 parts acrylamide, 14 parts acrylic acid-2-acrylamide-2-methylpropanesulfonic acid, 3.0 parts composite stabilizer, 12 parts urea, and 340 parts deionized water; it also includes 100 ppm EDTA-4Na, 10 ppm azobisisobutyrazoline hydrochloride, and 4 ppm redox initiator.

4. The stable formulation of anionic polyacrylamide according to any one of claims 1 to 3, characterized in that, The composite stabilizer is a mixture of ammonium sulfate and sodium 3-mercaptopropanesulfonate in a mass ratio of 1:

1.

5. The stable formulation of anionic polyacrylamide according to any one of claims 1 to 3, characterized in that, The redox initiator is tert-butanol hydrogen peroxide and ferrous ammonium sulfate.

6. The stable formulation of anionic polyacrylamide according to claim 5, characterized in that, The mass ratio of hydrogen peroxide tert-butanol to ferrous ammonium sulfate is 1:

1.

7. A method for preparing a stable formulation of anionic polyacrylamide as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Dissolve acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, composite stabilizer, and urea in deionized water, stir until completely dissolved, and adjust the pH of the solution to 3.7-4.

0. S2. Freeze the solution to -3°C and purge it with nitrogen gas to remove oxygen; S3, add EDTA-4Na and azobisisobutyrazoline hydrochloride in sequence; S4. Add a redox initiator at 0.5℃ to initiate the polymerization reaction; S5. Polymerize for 6-8 hours until gel state is reached to obtain a colloid; S6. Hydrolyze with NaOH, granulate, dry, grind, and sieve to obtain the anionic polyacrylamide.

8. The method according to claim 7, characterized in that, In step S2, nitrogen gas is introduced for 30 minutes.

9. The method according to claim 7, characterized in that, In step S6, the mass concentration of NaOH is 20-30%.

10. The application of anionic polyacrylamide as described in any one of claims 1 to 6 in wastewater treatment.

Images