Temperature-resistant and salt-resistant polyacrylamide flocculant and preparation method thereof
By combining supported microbial hydratase and green initiator, the preparation process of polyacrylamide flocculant was optimized, solving the problem of decreased flocculation efficiency under high salt and high temperature conditions, and achieving efficient and environmentally friendly flocculation effect.
Patent Information
- Application Number
- CN202511700097.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-19
- Publication Date
- 2026-02-24
AI Technical Summary
Traditional polyacrylamide flocculants are prone to molecular chain coiling and charge shielding in high-salt and high-temperature environments, resulting in a significant decrease in flocculation efficiency. Existing improved methods have problems such as complex synthesis processes, high costs, and environmental unfriendliness.
The acrylonitrile was catalyzed by a supported microbial hydratase to produce acrylamide, and a temperature- and salt-resistant polyacrylamide flocculant was formed through a special process. The enzyme activity was protected by bio-hydratase encapsulation technology, and the reaction conditions were optimized by combining green initiators and microcapsule sustained-release technology to improve the flocculation effect.
The prepared polyacrylamide flocculant maintains good flocculation activity under high temperature and high salt conditions, and has a high efficiency and environmentally friendly flocculation effect, reducing energy consumption and environmental pollution.
Smart Images
Figure CN121554644A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of flocculant preparation technology, specifically relating to a temperature-resistant and salt-resistant polyacrylamide flocculant and its preparation method. Background Technology
[0002] Polyacrylamide flocculant is a water-soluble polymer, insoluble in most organic solvents, and possesses excellent flocculation properties. It can reduce frictional resistance between liquids and can be classified into four types based on ionic characteristics: nonionic, anionic, cationic, and amphoteric. Polyacrylamide flocculants are widely used in thickening, colloid stabilization, drag reduction, bonding, film formation, and biomedical materials. In water treatment, it is used as a coagulant aid, flocculant, and sludge dewatering agent. In oil drilling and extraction, it is used as a precipitation agent and oil displacement agent. In papermaking, it is used as a retention aid and reinforcing agent.
[0003] However, traditional polyacrylamide (PAM) flocculants are prone to molecular chain coiling and charge shielding under high-salt and high-temperature environments, leading to a significant decrease in flocculation efficiency. Existing technologies often improve performance by introducing sulfonic acid monomers or hydrophobic modification, but these methods suffer from problems such as complex synthesis processes, high costs, and environmental unfriendliness.
[0004] Therefore, it is essential to develop a green and efficient preparation method for a temperature- and salt-resistant polyacrylamide flocculant. Summary of the Invention
[0005] The purpose of this invention is to address existing problems by providing a temperature- and salt-resistant polyacrylamide flocculant and its preparation method.
[0006] This invention is achieved through the following technical solution:
[0007] A method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant includes the following steps:
[0008] S1. Add acrylic acid and sodium hydroxide solution to a neutralization vessel and carry out a neutralization reaction at 16~19℃ and normal pressure to obtain sodium acrylate solution;
[0009] S2. Pure water and supported microbial hydratase are pumped into the catalytic reaction vessel, and then liquid acrylonitrile is added. Under the catalysis of the supported microbial hydratase, a hydration reaction occurs to generate acrylamide.
[0010] S3. Weigh out the corresponding weight parts of acrylamide monomer solution (90-120 parts), sodium acrylate solution (30-60 parts), urea (1.5-4.5 parts), soda ash (1.5-7.5 parts), sodium sulfate (3-12 parts), and pure water (150-250 parts) for later use.
[0011] S4. Add the weighed acrylamide monomer solution, sodium acrylate solution and pure water to the mixing tank, stir to form a homogeneous liquid, then add urea and sodium sulfate and stir until completely dissolved, add soda ash and stir to form a prepolymer liquid.
[0012] S5. Add the prepared prepolymer solution to the polymerization reactor, add 0.01~0.03 parts of initiator, and after deoxygenation treatment, the prepolymer solution polymerizes to generate polyacrylamide colloid.
[0013] S6. Compressed air is introduced from the top of the polymerization reactor to extrude the polyacrylamide colloid through the valve at the bottom of the polymerization reactor, and then it is conveyed to the granulator by a screw conveyor to obtain polyacrylamide colloid particles.
[0014] S7. The polyacrylamide colloidal granules are conveyed to the fluidized bed through a pipeline for drying. The dried granules are then conveyed to the pulverizer through a pipeline for pulverization. After pulverization, the granules are sieved. The sieving material that fails the sieving is returned to the fluidized bed for secondary drying, pulverization, and sieving. The sieving material that passes the sieving is weighed, inspected for quality, and then bagged and packaged.
[0015] Furthermore, the reaction process in step S2 is as follows:
[0016]
[0017] Furthermore, the preparation of the supported microbial hydratase described in step S2 includes the following steps:
[0018] (1) Add sodium alginate to phosphate buffer and stir until completely dissolved to obtain sodium alginate solution;
[0019] Chitosan was added to a 1% acetic acid solution and stirred until dissolved to obtain a chitosan solution.
[0020] (2) Add carbon nanotubes to phosphate buffer, disperse them evenly by ultrasonication, add nitrile hydratase, then mix them evenly with sodium alginate solution, add chitosan solution at a stirring speed of 80~160r / min, and stir to obtain a mixture.
[0021] (3) Use a syringe to add the mixture dropwise to the calcium chloride solution to form gel beads. After solidifying in the calcium chloride solution for 30-60 minutes, wash the gel beads with phosphate buffer. Transfer the cleaned gel beads to a 1-3% polysulfonate betaine solution. Then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to the polysulfonate betaine solution containing the gel beads at a molar ratio of 1-2:1. Stir at room temperature for 3-5 hours. Then wash the gel beads with phosphate buffer. After completion, store in phosphate buffer and store in a refrigerator at 4°C.
[0022] Furthermore, the concentration of the sodium alginate solution in step (1) is 2-3%, and the concentration of the chitosan solution is 1-2%.
[0023] Furthermore, the carbon nanotubes mentioned in step (2) have a diameter of 30~40nm and a length of 5~9μm, and the amount of carbon nanotubes added is 2~4% of the total mass of sodium alginate and chitosan.
[0024] Furthermore, the concentration of the calcium chloride solution mentioned in step (3) is 0.1~0.2 mol / L;
[0025] The total concentration of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) is 0.1~0.2 mol / L.
[0026] Furthermore, the reaction process in step S5 is as follows:
[0027]
[0028] Furthermore, the preparation of the initiator described in step S5 includes the following steps:
[0029] 1) Dissolve 0.1 mmol of ZnCl2 and 0.15 mmol of Na2SeO3 in ultrapure water, add tannic acid-gallic acid under nitrogen protection, stir and mix well, react under microwave conditions for 10-12 min, cool to room temperature and centrifuge to obtain ZnSe@PP nanocrystals, and store at 4℃ in the dark for later use.
[0030] 2) After preparing a GOx solution of 8-10 mg / L with phosphate solution, the GOx solution was mixed with glucose particles coated with β-cyclodextrin at a mass ratio of 1:4-6. Then, the mixture was formed in a chitosan / sodium alginate solution using microfluidic electrospray technology and freeze-dried to obtain microcapsules.
[0031] 3) The ZnSe@PP nanocrystals and microcapsules were ultrasonically dispersed in phosphate buffer at a mass ratio of 0.1:1~2 to obtain dispersion I;
[0032] 4) Add the polydopamine-modified silica carrier to phosphate buffer, sonicate to disperse evenly, add dispersion I, stir at 100~200 r / min for 1~2 h, centrifuge, wash the precipitate with phosphate buffer, disperse in phosphate buffer, and store at 4℃ in the dark for later use.
[0033] Furthermore, the molar ratio of tannic acid to gallic acid in step 1) is 1:1; the total mass of tannic acid and gallic acid is 18 to 23 times that of Na2SeO3.
[0034] Furthermore, the reaction temperature described in step 1) is 110~120℃.
[0035] Further, the concentration of chitosan in step 2) is 1-2 wt%, and the concentration of sodium alginate is 1-2 wt%.
[0036] Furthermore, the drying temperature in step S7 is 110℃~145℃, and the drying time is 1-2h.
[0037] The present invention has the following advantages over the prior art:
[0038] 1. In preparing a temperature- and salt-resistant polyacrylamide flocculant, this invention first employs a special process to encapsulate a biological hydration enzyme before using it in the preparation of acrylamide. This optimizes the preparation process, solving the problem of enzyme inactivation due to high temperatures. The process is easy to control. The prepared acrylamide monomer solution, sodium acrylate solution, and pure water are added to a mixing tank and stirred to form a homogeneous liquid. Then, urea and sodium sulfate are added and stirred until completely dissolved. Soda ash is added and stirred to form a prepolymer liquid, improving the reaction efficiency. In the polymerization reactor, the initiator decomposes to generate free radicals. These free radicals attack the double bonds of acrylamide and sodium acrylate, activating them and forming monomer free radicals. The activated monomer free radicals undergo addition reactions... The polymer should be continuously linked to form a linear polymer chain. Acrylamide provides amide groups, enhancing the polymer's water solubility and adsorption capacity. It binds to suspended particles through hydrogen bonds, improving flocculation. Sodium acrylate introduces carboxylate ions, imparting a negative charge to the polymer. This neutralization neutralizes the colloidal particles, while repulsion maintains chain extension, further enhancing flocculation. After copolymerization, the negative charge of the carboxylate and the polarity of the amide groups interact to form a more stable molecular network, inhibiting chain coiling and hydrolysis at high temperatures. Urea forms reversible hydrogen bonds with the amide groups of the polymer chain. At high temperatures, these hydrogen bonds partially dissociate, absorbing heat energy, and reconstruct upon cooling, improving thermal stability. Sodium acrylate and sodium sulfate work synergistically, with carboxylate ions combining with salt ions to form complexes, reducing the shielding effect of salt ions on the molecular chain, improving salt resistance, and maintaining flocculation activity. The polyacrylamide flocculant formed in this invention exhibits excellent temperature and salt resistance and maintains good flocculation activity, making it highly valuable for application.
[0039] 2. In this invention, microbial hydrated enzymes are encapsulated in a polymeric gel network, which can protect the enzymes from the influence of the external environment while allowing the substrates and products to diffuse freely in and out of the gel network, ensuring the free progress of the reaction.
[0040] 3. This invention employs a special process to prepare a highly efficient, precisely controlled, and environmentally friendly initiator. Compared to traditional initiators, this initiator can be excited under visible light. Visible light excitation replaces traditional high-temperature heating, significantly reducing energy consumption and avoiding the decomposition of heat-sensitive monomers (such as acrylic acid) caused by high temperatures. The three-dimensional porous carrier achieves uniform dispersion of the initiator, and combined with microcapsule-released glucose, it avoids explosive release of free radicals, precisely controlling the reaction. Furthermore, the chitosan / sodium alginate microcapsules and polydopamine carrier are biodegradable in the natural environment, making them safe and environmentally friendly. Attached Figure Description
[0041] Figure 1 A simplified process flow diagram for preparing acrylamide monomer solutions;
[0042] Figure 2 This is a process flow diagram for preparing the polyacrylamide flocculant of the present invention;
[0043] Figure 3 The figure shows the experimental results of the salt resistance of the polyacrylamide flocculant of the present invention. Detailed Implementation
[0044] To further explain the present invention, the following specific embodiments are described.
[0045] Example 1
[0046] A method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant includes the following steps:
[0047] S1. Add acrylic acid and sodium hydroxide solution to a neutralization vessel and carry out a neutralization reaction at 16°C and normal pressure to obtain sodium acrylate solution;
[0048] S2. Pure water and supported microbial hydratase are pumped into the catalytic reaction vessel, and then liquid acrylonitrile is added. Under the catalysis of the supported microbial hydratase, a hydration reaction occurs to generate acrylamide.
[0049] The preparation of the aforementioned loaded microbial hydratase includes the following steps:
[0050] (1) Add sodium alginate to phosphate buffer and stir until completely dissolved to obtain sodium alginate solution;
[0051] Chitosan was added to a 1% acetic acid solution and stirred until dissolved to obtain a chitosan solution.
[0052] The concentration of the sodium alginate solution is 2%, and the concentration of the chitosan solution is 1%.
[0053] (2) Carbon nanotubes (30 nm in diameter and 5 μm in length) were added to phosphate buffer and ultrasonically dispersed. Nitrile hydratase was added and then mixed with sodium alginate solution. Chitosan solution was added at a stirring speed of 80 r / min and stirred until a mixture was obtained.
[0054] The amount of carbon nanotubes added was 2% of the total mass of sodium alginate and chitosan;
[0055] (3) Add the mixture dropwise to the calcium chloride solution using a syringe to form gel beads. After solidifying in a 0.1 mol / L calcium chloride solution for 30 min, wash the gel beads with phosphate buffer. Transfer the cleaned gel beads to a 1% polysulfonate betaine solution. Then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to the polysulfonate betaine solution containing the gel beads in a 1:1 molar ratio. The total concentration of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) is 0.1 mol / L. Stir at room temperature for 3 h, then wash the gel beads with phosphate buffer. After completion, store in phosphate buffer and store in a 4°C refrigerator.
[0056] S3. Weigh out the corresponding weight parts of 90 parts acrylamide monomer solution, 30 parts sodium acrylate solution, 1.5 parts urea, 1.5 parts soda ash, 3 parts sodium sulfate, and 150 parts pure water for later use.
[0057] S4. Add the weighed acrylamide monomer solution, sodium acrylate solution and pure water to the mixing tank, stir to form a homogeneous liquid, then add urea and sodium sulfate and stir until completely dissolved, add soda ash and stir to form a prepolymer liquid.
[0058] S5. Add the prepared prepolymer solution to the polymerization reactor, add 0.02 parts of initiator, and after deoxygenation treatment, the prepolymer solution polymerizes to generate polyacrylamide colloid.
[0059] The preparation of the initiator includes the following steps:
[0060] 1) Dissolve 0.1 mmol of ZnCl2 and 0.15 mmol of Na2SeO3 in ultrapure water. Under nitrogen protection, add tannic acid-gallic acid (molar ratio 1:1). The total mass of tannic acid-gallic acid is 18 times that of Na2SeO3. After stirring and mixing, react at 110℃ for 10 min under microwave conditions. After cooling to room temperature, centrifuge to obtain ZnSe@PP nanocrystals, and store at 4℃ in the dark for later use.
[0061] 2) After preparing an 8 mg / L GOx solution with phosphate solution, the GOx solution was mixed with β-cyclodextrin-coated glucose particles at a mass ratio of 1:4. Then, the mixture was formed in a chitosan / sodium alginate solution using microfluidic electrospray technology. The concentration of chitosan was 1 wt% and the concentration of sodium alginate was 1 wt%. The mixture was then freeze-dried to obtain microcapsules.
[0062] 3) The ZnSe@PP nanocrystals and microcapsules were ultrasonically dispersed in phosphate buffer at a mass ratio of 0.1:1 to obtain dispersion I;
[0063] 4) Add the polydopamine-modified silica carrier to phosphate buffer, sonicate to disperse evenly, add dispersion I, stir at 100 r / min for 1 h, centrifuge, wash the precipitate with phosphate buffer, disperse in phosphate buffer, and store at 4℃ in the dark for later use.
[0064] S6. Compressed air is introduced from the top of the polymerization reactor to extrude the polyacrylamide colloid through the valve at the bottom of the polymerization reactor, and then it is conveyed to the granulator by a screw conveyor to obtain polyacrylamide colloid particles.
[0065] S7. The polyacrylamide colloidal particles are conveyed to a fluidized bed through a pipeline for drying at 110℃ for 1 hour. The dried particles are then conveyed to a pulverizer through a pipeline for pulverization. After pulverization, the particles are sieved. Materials that fail the sieve test are returned to the fluidized bed for secondary drying, followed by pulverization and sieve testing. Materials that pass the sieve test are weighed, inspected for quality, and then bagged and packaged.
[0066] Example 2
[0067] A method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant includes the following steps:
[0068] S1. Add acrylic acid and sodium hydroxide solution to a neutralization vessel and carry out a neutralization reaction at 18°C and normal pressure to obtain sodium acrylate solution;
[0069] S2. Pure water and supported microbial hydratase are pumped into the catalytic reaction vessel, and then liquid acrylonitrile is added. Under the catalysis of the supported microbial hydratase, a hydration reaction occurs to generate acrylamide.
[0070] The preparation of the aforementioned loaded microbial hydratase includes the following steps:
[0071] (1) Add sodium alginate to phosphate buffer and stir until completely dissolved to obtain sodium alginate solution;
[0072] Chitosan was added to a 1% acetic acid solution and stirred until dissolved to obtain a chitosan solution.
[0073] The concentration of the sodium alginate solution is 2.5%, and the concentration of the chitosan solution is 1.5%.
[0074] (2) Carbon nanotubes (35 nm in diameter and 7 μm in length) were added to phosphate buffer and ultrasonically dispersed. Nitrile hydratase was added and then mixed with sodium alginate solution. Chitosan solution was added at a stirring speed of 120 r / min and stirred until a mixture was obtained.
[0075] The amount of carbon nanotubes added was 3% of the total mass of sodium alginate and chitosan;
[0076] (3) Add the mixture dropwise to the calcium chloride solution using a syringe to form gel beads. After solidifying in a 0.15 mol / L calcium chloride solution for 45 min, wash the gel beads with phosphate buffer. Transfer the cleaned gel beads to a 1-3% polysulfonate betaine solution. Then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to the polysulfonate betaine solution containing the gel beads at a molar ratio of 1-2:1. The total concentration of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) is 0.15 mol / L. Stir at room temperature for 4 h, then wash the gel beads with phosphate buffer. After completion, store in phosphate buffer and store in a 4°C refrigerator.
[0077] S3. Weigh out the corresponding weight parts of 105 parts of acrylamide monomer solution, 45 parts of sodium acrylate solution, 3 parts of urea, 4.5 parts of soda ash, 7 parts of sodium sulfate, and 200 parts of pure water for later use.
[0078] S4. Add the weighed acrylamide monomer solution, sodium acrylate solution and pure water to the mixing tank, stir to form a homogeneous liquid, then add urea and sodium sulfate and stir until completely dissolved, add soda ash and stir to form a prepolymer liquid.
[0079] S5. Add the prepared prepolymer solution to the polymerization reactor, add 0.02 parts of initiator, and after deoxygenation treatment, the prepolymer solution polymerizes to generate polyacrylamide colloid.
[0080] The preparation of the initiator includes the following steps:
[0081] 1) Dissolve 0.1 mmol of ZnCl2 and 0.15 mmol of Na2SeO3 in ultrapure water. Under nitrogen protection, add tannic acid-gallic acid (molar ratio 1:1). The total mass of tannic acid-gallic acid is 20 times that of Na2SeO3. After stirring and mixing, react at 115℃ for 11 min under microwave conditions. After cooling to room temperature, centrifuge to obtain ZnSe@PP nanocrystals, and store at 4℃ in the dark for later use.
[0082] 2) After preparing a 9 mg / L GOx solution with phosphate solution, the GOx solution was mixed with β-cyclodextrin-coated glucose particles at a mass ratio of 1:5. Then, the mixture was formed in a chitosan / sodium alginate solution using microfluidic electrospray technology. The concentration of chitosan was 1.5 wt%, the concentration of sodium alginate was 1.5 wt%, and the mixture was freeze-dried to obtain microcapsules.
[0083] 3) The ZnSe@PP nanocrystals and microcapsules were ultrasonically dispersed in phosphate buffer at a mass ratio of 0.1:1.5 to obtain dispersion I;
[0084] 4) Add the polydopamine-modified silica carrier to phosphate buffer, sonicate to disperse evenly, add dispersion I, stir at 150 r / min for 1.5 h, centrifuge, wash the precipitate with phosphate buffer, disperse in phosphate buffer, and store at 4℃ in the dark for later use.
[0085] S6. Compressed air is introduced from the top of the polymerization reactor to extrude the polyacrylamide colloid through the valve at the bottom of the polymerization reactor, and then it is conveyed to the granulator by a screw conveyor to obtain polyacrylamide colloid particles.
[0086] S7. The polyacrylamide colloidal particles are conveyed to a fluidized bed through a pipeline for drying at 125℃ for 1.5 hours. The dried particles are then conveyed to a pulverizer through a pipeline for pulverization. After pulverization, the particles are sieved. Materials that fail the sieve test are returned to the fluidized bed for secondary drying, followed by pulverization and sieve testing. Materials that pass the sieve test are weighed, inspected for quality, and then bagged and packaged.
[0087] Example 3
[0088] A method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant includes the following steps:
[0089] S1. Add acrylic acid and sodium hydroxide solution to a neutralization vessel and carry out a neutralization reaction at 19°C and normal pressure to obtain sodium acrylate solution;
[0090] S2. Pure water and supported microbial hydratase are pumped into the catalytic reaction vessel, and then liquid acrylonitrile is added. Under the catalysis of the supported microbial hydratase, a hydration reaction occurs to generate acrylamide.
[0091] The preparation of the aforementioned loaded microbial hydratase includes the following steps:
[0092] (1) Add sodium alginate to phosphate buffer and stir until completely dissolved to obtain sodium alginate solution;
[0093] Chitosan was added to a 1% acetic acid solution and stirred until dissolved to obtain a chitosan solution.
[0094] The concentration of the sodium alginate solution is 3%, and the concentration of the chitosan solution is 2%.
[0095] (2) Carbon nanotubes (40 nm in diameter and 9 μm in length) were added to phosphate buffer and ultrasonically dispersed. Nitrile hydratase was added and then mixed with sodium alginate solution. Chitosan solution was added at a stirring speed of 160 r / min and stirred until a mixture was obtained.
[0096] The amount of carbon nanotubes added was 4% of the total mass of sodium alginate and chitosan;
[0097] (3) Add the mixture dropwise to the calcium chloride solution using a syringe to form gel beads. After solidifying in a 0.2 mol / L calcium chloride solution for 60 min, wash the gel beads with phosphate buffer. Transfer the cleaned gel beads to a 1-3% polysulfonate betaine solution. Then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to the polysulfonate betaine solution containing the gel beads at a molar ratio of 2:1. The total concentration of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) is 0.2 mol / L. Stir at room temperature for 5 h, then wash the gel beads with phosphate buffer. After completion, store in phosphate buffer and store in a refrigerator at 4°C.
[0098] S3. Weigh out the corresponding weight parts of 120 parts of acrylamide monomer solution, 60 parts of sodium acrylate solution, 4.5 parts of urea, 7.5 parts of soda ash, 12 parts of sodium sulfate, and 250 parts of pure water for later use.
[0099] S4. Add the weighed acrylamide monomer solution, sodium acrylate solution and pure water to the mixing tank, stir to form a homogeneous liquid, then add urea and sodium sulfate and stir until completely dissolved, add soda ash and stir to form a prepolymer liquid.
[0100] S5. Add the prepared prepolymer solution to the polymerization reactor, add 0.03 parts of initiator, and after deoxygenation treatment, the prepolymer solution polymerizes to generate polyacrylamide colloid.
[0101] The preparation of the initiator includes the following steps:
[0102] 1) Dissolve 0.1 mmol of ZnCl2 and 0.15 mmol of Na2SeO3 in ultrapure water. Under nitrogen protection, add tannic acid-gallic acid (molar ratio 1:1). The total mass of tannic acid-gallic acid is 23 times that of Na2SeO3. After stirring and mixing, react at 120℃ for 12 min under microwave conditions. After cooling to room temperature, centrifuge to obtain ZnSe@PP nanocrystals, and store at 4℃ in the dark for later use.
[0103] 2) After preparing a 10 mg / L GOx solution with phosphate solution, the GOx solution was mixed with β-cyclodextrin-coated glucose particles at a mass ratio of 1:6. Then, the mixture was formed in a chitosan / sodium alginate solution using microfluidic electrospray technology. The concentration of chitosan was 2 wt%, the concentration of sodium alginate was 2 wt%, and the mixture was freeze-dried to obtain microcapsules.
[0104] 3) The ZnSe@PP nanocrystals and microcapsules were ultrasonically dispersed in phosphate buffer at a mass ratio of 0.1:2 to obtain dispersion I;
[0105] 4) Add the polydopamine-modified silica carrier to phosphate buffer, sonicate to disperse evenly, add dispersion I, stir at 200 r / min for 2 h, centrifuge, wash the precipitate with phosphate buffer, disperse in phosphate buffer, and store at 4℃ in the dark for later use.
[0106] S6. Compressed air is introduced from the top of the polymerization reactor to extrude the polyacrylamide colloid through the valve at the bottom of the polymerization reactor, and then it is conveyed to the granulator by a screw conveyor to obtain polyacrylamide colloid particles.
[0107] S7. The polyacrylamide colloidal particles are conveyed to a fluidized bed through a pipeline for drying at 145℃ for 2 hours. The dried particles are then conveyed to a pulverizer through a pipeline for pulverization. After pulverization, the particles are sieved. Materials that fail the sieve test are returned to the fluidized bed for secondary drying, followed by pulverization and sieve testing. Materials that pass the sieve test are weighed, inspected for quality, and then bagged and packaged.
[0108] Comparative Example 1
[0109] Based on Example 2, only the preparation method of the supported microbial hydratase was changed, while the rest of the technical solutions were the same as those in Example 2.
[0110] The preparation of the loaded microbial hydratase in Comparative Example 1 includes the following steps:
[0111] (1) Add sodium alginate to phosphate buffer and stir until completely dissolved to obtain sodium alginate solution;
[0112] Chitosan was added to a 1% acetic acid solution and stirred until dissolved to obtain a chitosan solution.
[0113] The concentration of the sodium alginate solution is 2.5%, and the concentration of the chitosan solution is 1.5%.
[0114] (2) Disperse the nitrile hydratase in phosphate buffer by ultrasonication, then mix it evenly with sodium alginate solution, add chitosan solution at a stirring speed of 120 r / min, and stir to obtain a mixture.
[0115] The amount of carbon nanotubes added was 3% of the total mass of sodium alginate and chitosan;
[0116] (3) Add the mixture dropwise to the calcium chloride solution using a syringe to form gel beads. After solidifying in a 0.15 mol / L calcium chloride solution for 45 min, wash the gel beads with phosphate buffer. Transfer the cleaned gel beads to a 1-3% polysulfonate betaine solution. Then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to the polysulfonate betaine solution containing the gel beads at a molar ratio of 1-2:1. The total concentration of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) is 0.15 mol / L. Stir at room temperature for 4 h, then wash the gel beads with phosphate buffer. After completion, store in phosphate buffer and store in a 4°C refrigerator.
[0117] Comparative Example 2
[0118] Based on Example 2, only the preparation method of the supported microbial hydratase was changed, while the rest of the technical solutions were the same as those in Example 2.
[0119] The preparation of the supported microbial hydratase described in Comparative Example 2 includes the following steps:
[0120] (1) Add sodium alginate to phosphate buffer and stir until completely dissolved to obtain sodium alginate solution;
[0121] Chitosan was added to a 1% acetic acid solution and stirred until dissolved to obtain a chitosan solution.
[0122] The concentration of the sodium alginate solution is 2.5%, and the concentration of the chitosan solution is 1.5%.
[0123] (2) Carbon nanotubes (35 nm in diameter and 7 μm in length) were added to phosphate buffer and ultrasonically dispersed. Nitrile hydratase was added and then mixed with sodium alginate solution. Chitosan solution was added at a stirring speed of 120 r / min and stirred until a mixture was obtained.
[0124] The amount of carbon nanotubes added was 3% of the total mass of sodium alginate and chitosan;
[0125] (3) Use a syringe to add the mixture dropwise to the calcium chloride solution to form gel beads. After solidifying in a 0.15 mol / L calcium chloride solution for 45 min, wash the gel beads with phosphate buffer. After completion, store in phosphate buffer and store in a refrigerator at 4°C.
[0126] Comparative Example 3
[0127] Based on Example 2, the loaded microbial hydratase was replaced with untreated nitrile hydratase, and the rest of the technical solutions were the same as those in Example 2.
[0128] Comparative Example 4
[0129] A method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant includes the following steps:
[0130] S1. Add acrylic acid and sodium hydroxide solution to a neutralization vessel and carry out a neutralization reaction at 18°C and normal pressure to obtain sodium acrylate solution;
[0131] S2. Pure water and supported microbial hydratase are pumped into the catalytic reaction vessel, and then liquid acrylonitrile is added. Under the catalysis of the supported microbial hydratase, a hydration reaction occurs to generate acrylamide.
[0132] The preparation of the aforementioned loaded microbial hydratase includes the following steps:
[0133] (1) Add sodium alginate to phosphate buffer and stir until completely dissolved to obtain sodium alginate solution;
[0134] Chitosan was added to a 1% acetic acid solution and stirred until dissolved to obtain a chitosan solution.
[0135] The concentration of the sodium alginate solution is 2.5%, and the concentration of the chitosan solution is 1.5%.
[0136] (2) Carbon nanotubes (35 nm in diameter and 7 μm in length) were added to phosphate buffer and ultrasonically dispersed. Nitrile hydratase was added and then mixed with sodium alginate solution. Chitosan solution was added at a stirring speed of 120 r / min and stirred until a mixture was obtained.
[0137] The amount of carbon nanotubes added was 3% of the total mass of sodium alginate and chitosan;
[0138] (3) Add the mixture dropwise to the calcium chloride solution using a syringe to form gel beads. After solidifying in a 0.15 mol / L calcium chloride solution for 45 min, wash the gel beads with phosphate buffer. Transfer the cleaned gel beads to a 1-3% polysulfonate betaine solution. Then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to the polysulfonate betaine solution containing the gel beads at a molar ratio of 1-2:1. The total concentration of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) is 0.15 mol / L. Stir at room temperature for 4 h, then wash the gel beads with phosphate buffer. After completion, store in phosphate buffer and store in a 4°C refrigerator.
[0139] S3. Weigh out the corresponding weight parts of 105 parts of acrylamide monomer solution, 45 parts of sodium acrylate solution, 3 parts of urea, 4.5 parts of soda ash, 7 parts of sodium sulfate, and 200 parts of pure water for later use.
[0140] S4. The acrylamide monomer solution, sodium acrylate solution, urea, soda ash, sodium sulfate and pure water weighed above are added to the polymerization kettle in sequence. After stirring and mixing, 0.02 parts of initiator are added. After deoxygenation treatment, the prepolymer solution is polymerized to generate polyacrylamide colloid.
[0141] The preparation of the initiator includes the following steps:
[0142] 1) Dissolve 0.1 mmol of ZnCl2 and 0.15 mmol of Na2SeO3 in ultrapure water. Under nitrogen protection, add tannic acid-gallic acid (molar ratio 1:1). The total mass of tannic acid-gallic acid is 20 times that of Na2SeO3. After stirring and mixing, react at 115℃ for 11 min under microwave conditions. After cooling to room temperature, centrifuge to obtain ZnSe@PP nanocrystals, and store at 4℃ in the dark for later use.
[0143] 2) After preparing a 9 mg / L GOx solution with phosphate solution, the GOx solution was mixed with β-cyclodextrin-coated glucose particles at a mass ratio of 1:5. Then, the mixture was formed in a chitosan / sodium alginate solution using microfluidic electrospray technology. The concentration of chitosan was 1.5 wt%, the concentration of sodium alginate was 1.5 wt%, and the mixture was freeze-dried to obtain microcapsules.
[0144] 3) The ZnSe@PP nanocrystals and microcapsules were ultrasonically dispersed in phosphate buffer at a mass ratio of 0.1:1.5 to obtain dispersion I;
[0145] 4) Add the polydopamine-modified silica carrier to phosphate buffer, sonicate to disperse evenly, add dispersion I, stir at 150 r / min for 1.5 h, centrifuge, wash the precipitate with phosphate buffer, disperse in phosphate buffer, and store at 4℃ in the dark for later use.
[0146] S6. Compressed air is introduced from the top of the polymerization reactor to extrude the polyacrylamide colloid through the valve at the bottom of the polymerization reactor, and then it is conveyed to the granulator by a screw conveyor to obtain polyacrylamide colloid particles.
[0147] S7. The polyacrylamide colloidal particles are conveyed to a fluidized bed through a pipeline for drying at 125℃ for 1.5 hours. The dried particles are then conveyed to a pulverizer through a pipeline for pulverization. After pulverization, the particles are sieved. Materials that fail the sieve test are returned to the fluidized bed for secondary drying, followed by pulverization and sieve testing. Materials that pass the sieve test are weighed, inspected for quality, and then bagged and packaged.
[0148] Comparative Example 5
[0149] Based on Example 2, the initiator was replaced with an equal mass of ammonium persulfate, and the rest of the technical solutions were the same as those in Example 2.
[0150] Performance testing
[0151] 1. Temperature resistance test
[0152] The flocculants prepared by the methods of each embodiment and comparative example were placed in a constant temperature phase at 90°C for 24 h and 48 h, respectively, and then the viscosity of the flocculants was measured using a rotational viscometer.
[0153] The test results are shown in Table 1 below.
[0154] Table 1
[0155]
[0156] As shown in Table 1 above, the viscosity retention rate of the flocculants in Examples 1-3 reached 89-92% after treatment at 90℃ for 24 hours and 78-82% after treatment at 90℃ for 48 hours, which is significantly higher than that of the comparative example. This indicates that the process of the present invention significantly improves the thermal stability of the flocculant and slows down the degradation rate of the molecular chain at high temperature.
[0157] 2. Salt resistance test
[0158] Simulated saline solutions with NaCl concentrations of 0.5%, 1%, 2%, and 3% were prepared respectively. Then, each group of flocculants was dissolved in salt solutions of different concentrations, and the viscosity was measured after standing for 2 hours.
[0159] The test results are as follows Figure 3 As shown.
[0160] Depend on Figure 2 It can be seen that as the salt concentration increases, the viscosity retention rate decreases. In a 3% salt solution, the viscosity retention rate of Example 2 is still 75%, which is significantly better than that of the comparative example, indicating that the flocculant prepared by the method of the present invention has good salt resistance.
[0161] 3. Flocculation performance test
[0162] Using kaolin (500 mg / L), humic acid (100 mg / L), CaCl2 (200 mg / L), and pH=7.0 as raw materials, simulated wastewater was prepared. The initial turbidity was measured to be approximately 800 NTU. After preparation, flocculant was added to the simulated wastewater at a dosage of 0.5 mg / L. The mixture was stirred at 200 r / min for 2 min, then at 50 r / min for 5 min. After standing for 30 min, the supernatant was taken to measure the turbidity.
[0163] The test results are shown in Table 2 below.
[0164] Table 2
[0165] Turbidity (NTU) Example 1 40 Example 2 36 Example 3 39 Comparative Example 1 62 Comparative Example 2 73 Comparative Example 3 99 Comparative Example 4 59 Comparative Example 5 103
[0166] As shown in Table 2 above, the turbidity of the supernatant prepared by the method of the present invention decreased to 36 NTU after 30 minutes of wastewater treatment. Its removal effect on suspended solids was significantly better than that of the comparative example, indicating that the flocculant prepared by the method of the present invention has a good flocculation effect.
[0167] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant, characterized in that, Includes the following steps: S1. Add acrylic acid and sodium hydroxide solution to a neutralization vessel and carry out a neutralization reaction at 16~19℃ and normal pressure to obtain sodium acrylate solution; S2. Pure water and supported microbial hydratase are pumped into the catalytic reaction vessel, and then liquid acrylonitrile is added. Under the catalysis of the supported microbial hydratase, a hydration reaction occurs to generate acrylamide. S3. Weigh out the corresponding weight parts of acrylamide monomer solution (90-120 parts), sodium acrylate solution (30-60 parts), urea (1.5-4.5 parts), soda ash (1.5-7.5 parts), sodium sulfate (3-12 parts), and pure water (150-250 parts) for later use. S4. Add the weighed acrylamide monomer solution, sodium acrylate solution and pure water to the mixing tank, stir to form a homogeneous liquid, then add urea and sodium sulfate and stir until completely dissolved, add soda ash and stir to form a prepolymer liquid. S5. Add the prepared prepolymer solution to the polymerization reactor, add 0.01~0.03 parts of initiator, remove oxygen, and the prepolymer solution polymerizes to generate polyacrylamide colloid. S6. Compressed air is introduced from the top of the polymerization reactor to extrude the polyacrylamide colloid through the valve at the bottom of the polymerization reactor, and then it is conveyed to the granulator by a screw conveyor to obtain polyacrylamide colloid particles. S7. The polyacrylamide colloidal granules are conveyed to the fluidized bed through a pipeline for drying. The dried granules are then conveyed to the pulverizer through a pipeline for pulverization. After pulverization, the granules are sieved. The sieving material that fails the sieving is returned to the fluidized bed for secondary drying, pulverization, and sieving. The sieving material that passes the sieving is weighed, inspected for quality, and then bagged and packaged.
2. The preparation method of the temperature-resistant and salt-resistant polyacrylamide flocculant according to claim 1, characterized in that, The preparation of the loaded microbial hydratase described in step S2 includes the following steps: (1) Add sodium alginate to phosphate buffer and stir until completely dissolved to obtain sodium alginate solution; Chitosan was added to a 1% acetic acid solution and stirred until dissolved to obtain a chitosan solution. (2) Add carbon nanotubes to phosphate buffer, disperse them evenly by ultrasonication, add nitrile hydratase, then mix them evenly with sodium alginate solution, add chitosan solution at a stirring speed of 80~160r / min, and stir to obtain a mixture. (3) Use a syringe to add the mixture dropwise to the calcium chloride solution to form gel beads. After solidifying in the calcium chloride solution for 30-60 minutes, wash the gel beads with phosphate buffer. Transfer the cleaned gel beads to a 1-3% polysulfonate betaine solution. Then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to the polysulfonate betaine solution containing the gel beads at a molar ratio of 1-2:
1. Stir at room temperature for 3-5 hours. Then wash the gel beads with phosphate buffer. After completion, store in phosphate buffer and store in a refrigerator at 4°C.
3. The preparation method of the temperature-resistant and salt-resistant polyacrylamide flocculant according to claim 2, characterized in that, The concentration of sodium alginate solution in step (1) is 2-3%, and the concentration of chitosan solution is 1-2%.
4. The preparation method of the temperature-resistant and salt-resistant polyacrylamide flocculant according to claim 2, characterized in that, The carbon nanotubes mentioned in step (2) have a diameter of 30~40nm and a length of 5~9μm. The amount of carbon nanotubes added is 2~4% of the total mass of sodium alginate and chitosan.
5. The preparation method of a temperature-resistant and salt-resistant polyacrylamide flocculant according to claim 2, characterized in that, The concentration of the calcium chloride solution mentioned in step (3) is 0.1~0.2 mol / L; The total concentration of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide is 0.1~0.2 mol / L.
6. The method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant according to claim 1, characterized in that, The preparation of the initiator described in step S5 includes the following steps: 1) Dissolve 0.1 mmol of ZnCl2 and 0.15 mmol of Na2SeO3 in ultrapure water, add tannic acid-gallic acid under nitrogen protection, stir and mix well, react under microwave conditions for 10-12 min, cool to room temperature and centrifuge to obtain ZnSe@PP nanocrystals, and store at 4℃ in the dark for later use. 2) After preparing a GOx solution of 8-10 mg / L with phosphate solution, the GOx solution was mixed with glucose particles coated with β-cyclodextrin at a mass ratio of 1:4-6. Then, the mixture was formed in a chitosan / sodium alginate solution using microfluidic electrospray technology and freeze-dried to obtain microcapsules. 3) The ZnSe@PP nanocrystals and microcapsules were ultrasonically dispersed in phosphate buffer at a mass ratio of 0.1:1~2 to obtain dispersion I; 4) Add the polydopamine-modified silica carrier to phosphate buffer, sonicate to disperse evenly, add dispersion I, stir at 100~200 r / min for 1~2 h, centrifuge, wash the precipitate with phosphate buffer, disperse in phosphate buffer, and store at 4℃ in the dark for later use.
7. The method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant according to claim 6, characterized in that, The molar ratio of tannic acid to gallic acid in step 1) is 1:1; the total mass of tannic acid and gallic acid is 18 to 23 times that of Na2SeO3.
8. The preparation method of a temperature-resistant and salt-resistant polyacrylamide flocculant according to claim 6, characterized in that, The reaction temperature described in step 1) is 110~120℃.
9. The method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant according to claim 6, characterized in that, The concentration of chitosan in step 2) is 1-2 wt%, and the concentration of sodium alginate is 1-2 wt%.
10. The method for preparing a temperature-resistant and salt-resistant polyacrylamide flocculant according to claim 1, characterized in that, The drying temperature in step S7 is 110℃~145℃, and the drying time is 1~2h.