Hydrophobic modified polyacrylamide for deep dehydration of papermaking sludge and preparation method thereof

Abstract

The invention discloses hydrophobic modified polyacrylamide for deep dehydration of papermaking sludge, which is prepared from the following components in parts by weight: 95 to 105 parts of acrylamide, 20 to 30 parts of 2-acrylamide-2-methylpropanesulfonic acid, 4 to 6 parts of ethylene glycol, 8 to 12 parts of dodecyl acrylate, 0.03 to 0.06 part of EDTA-2Na (Ethylene Diamine Tetraacetic Acid), 0.05 to 0.1 part of N-octyl bisacrylamide and 0.03 to 0.04 part of ammonium persulfate. 0.025 to 0.035 part of ammonium ferrous sulfate and 370 to 380 parts of deionized water. The invention also provides a preparation method of the hydrophobic modified polyacrylamide. The polyacrylamide hydrophilic main chain guarantees the water solubility of the product, the hydrophobic side chain effectively captures hydrophobic pollutants through association, and the amide group can specifically anchor the fiber surface, so that efficient synergistic adsorption of impurities with different properties is realized, fiber particles, colloids and hydrophobic pollutants can be synchronously captured, and the adsorption efficiency is improved. Compact and high-strength flocs are formed, and the solid-liquid separation efficiency is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of papermaking sludge treatment technology, specifically relating to a hydrophobically modified polyacrylamide for deep dewatering of papermaking sludge and its preparation method. Background Technology

[0002] Deep dewatering aims to further reduce the moisture content of sludge from about 80% after conventional mechanical dewatering to 60% or even lower, thereby significantly reducing sludge volume, facilitating subsequent transportation, incineration or resource utilization, and reducing disposal costs.

[0003] Currently, the core prerequisite for achieving deep dewatering is effective chemical conditioning of sludge to disrupt its stable colloidal structure and release bound water. Cationic polyacrylamide (CPAM) is the most widely used sludge conditioner, which causes sludge particles to flocculate through charge neutralization and adsorption bridging. However, traditional CPAM has inherent limitations when treating papermaking sludge, including the problem of "hydration shell," poor hydrophilicity and permeability of flocs, and insufficient ability to handle complex components.

[0004] Therefore, the market urgently needs a hydrophobically modified polyacrylamide specifically designed for the characteristics of papermaking sludge. This product needs to effectively overcome the "hydration shell" barrier, forming hydrophobic, dense flocs, thereby achieving deep dewatering under conventional mechanical dewatering conditions and solving the pain points of sludge disposal for papermaking enterprises. Summary of the Invention

[0005] The purpose of this invention is to provide a hydrophobically modified polyacrylamide with good flocculation effect, suitable for deep dewatering of papermaking sludge, and its preparation method.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A hydrophobically modified polyacrylamide for deep dewatering of papermaking sludge comprises the following components by weight: Acrylamide 95-105 parts, 2-acrylamide-2-methylpropanesulfonic acid 20-30 parts, ethylene glycol 4-6 parts, dodecyl acrylate 8-12 parts, EDTA-2Na 0.03-0.06 parts, N-octylbisacrylamide 0.05-0.1 parts, ammonium persulfate 0.03-0.04 parts, ferrous ammonium sulfate 0.025-0.035 parts, deionized water 370-380 parts.

[0007] Preferably, the hydrophobically modified polyacrylamide comprises the following components by weight: 100 parts acrylamide, 20 parts 2-acrylamide-2-methylpropanesulfonic acid, 5 parts ethylene glycol, 10 parts dodecyl acrylate, 0.05 parts EDTA-2Na, 0.1 parts N-octylbisacrylamide, 0.04 parts ammonium persulfate, 0.035 parts ferrous ammonium sulfate, and 375 parts deionized water.

[0008] Preferably, the hydrophobically modified polyacrylamide comprises the following components by weight: 105 parts acrylamide, 205 parts 2-acrylamide-2-methylpropanesulfonic acid, 6 parts ethylene glycol, 12 parts dodecyl acrylate, 0.06 parts EDTA-2Na, 0.08 parts N-octylbisacrylamide, 0.03 parts ammonium persulfate, 0.025 parts ferrous ammonium sulfate, and 380 parts deionized water.

[0009] Preferably, the hydrophobically modified polyacrylamide comprises the following components by weight: 95-100 parts acrylamide, 30 parts 2-acrylamido-2-methylpropanesulfonic acid, 4 parts ethylene glycol, 8 parts dodecyl acrylate, 0.03 parts EDTA-2Na, 0.05 parts N-octylbisacrylamide, 0.04 parts ammonium persulfate, 0.03 parts ferrous ammonium sulfate, and 370 parts deionized water.

[0010] Preferably, the hydrophobic modified polyacrylamide has a molecular weight of 13.5-15.5 million.

[0011] The present invention also provides a method for preparing the hydrophobically modified polyacrylamide, which includes the following steps: S1. Dissolve acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, and ethylene glycol in deionized water and stir until completely dissolved. S2. Add dodecyl acrylate and stir until the solution is homogeneous and transparent. Add EDTA-2Na and N-octylbisacrylamide and stir until homogeneous. S3. Introduce nitrogen gas to purge oxygen. Add ammonium persulfate and ferrous ammonium sulfate to initiate polymerization. React at 50-60℃ for 5-8 hours to form a colloid. S4. After granulation, drying, crushing and sieving of the colloid, the hydrophobic modified polyacrylamide is obtained.

[0012] Preferably, in step S2, the nitrogen gas is introduced for 30 minutes.

[0013] Compared with the prior art, the present invention has the following beneficial effects: (1) By constructing a “hydrophobic-hydrophilic synergistic adsorption” structure, the overall processing capacity of the polymer is significantly improved. This structure forms a unique three-dimensional configuration of “hydrophilic backbone-hydrophobic side chain-fiber affinity site” by simultaneously introducing long-chain alkyl hydrophobic groups (dodecyl) and fiber affinity groups (amide groups) onto the PAM molecular chain. The hydrophilic backbone ensures the water solubility of the product, the hydrophobic side chain effectively captures hydrophobic pollutants through association, and the amide group can specifically anchor to the fiber surface, thus achieving efficient synergistic adsorption of impurities with different properties.

[0014] (2) By using the bifunctional hydrophobic crosslinking agent N-octylbisacrylamide for regulation, the PAM molecular chains form high-density hydrophobic crosslinking nodes, achieving "high-density crosslinking flocculation". This structure enhances the polymer's bridging ability and network density, enabling it to simultaneously capture fiber particles, colloids, and hydrophobic pollutants, forming dense and high-strength flocs. These flocs exhibit good shear resistance, fast settling speed, and significantly improved solid-liquid separation efficiency.

[0015] (3) Salt-resistant monomer 2-acrylamide-2-methylpropanesulfonic acid (AMPS) was introduced to address the impact of high-salt environments in papermaking sludge. The sulfonic acid group has a high dissociation constant and strong hydration ability. It can maintain the extended conformation of polymer molecular chains even in the presence of high-valence metal ions, effectively resisting the chain curling phenomenon caused by salt, thereby ensuring the flocculation stability and treatment effect of CPAM under high-salt conditions. Detailed Implementation

[0016] 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.

[0017] In the description of this invention, unless otherwise explicitly defined, terms such as heating, cleaning, weighing, and freezing should be interpreted broadly. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0018] In the description of this invention, references to terms such as "some embodiments" and "examples" indicate that the specific methods or materials described in connection with that embodiment or example are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the specific methods and materials described may be combined in any suitable manner in one or more embodiments or examples.

[0019] 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.

[0020] 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.

[0021] Example 1 Dissolve 100g acrylamide, 20g 2-acrylamide-2-methylpropanesulfonic acid, and 5g ethylene glycol in 375g deionized water and stir until completely dissolved.

[0022] Then add 10g of dodecyl acrylate and stir at high speed for 30 minutes (800 rpm) until the solution is homogeneous and transparent. Add 0.05g of EDTA-2Na and 0.1g of N-octylbisacrylamide and stir until homogeneous.

[0023] Nitrogen gas was introduced for 30 minutes to remove oxygen. 0.04 g of ammonium persulfate and 0.035 g of ferrous ammonium sulfate were added to initiate polymerization. The reaction was carried out at 50°C for 6 hours to form a colloid.

[0024] After granulation, drying, crushing, and sieving of the colloid, polyacrylamide product is obtained.

[0025] Polyacrylamide molecular weight: 14 million.

[0026] Example 2 Dissolve 105g acrylamide, 25g 2-acrylamide-2-methylpropanesulfonic acid, and 6g ethylene glycol in 380g deionized water and stir until completely dissolved.

[0027] Then add 12g of dodecyl acrylate and stir at high speed for 30 minutes (800 rpm) until the solution is homogeneous and transparent. Add 0.06g of EDTA-2Na and 0.08g of N-octylbisacrylamide and stir until homogeneous.

[0028] Nitrogen gas was introduced for 30 minutes to remove oxygen. 0.03 g of ammonium persulfate and 0.025 g of ferrous ammonium sulfate were added to initiate polymerization. The reaction was carried out at 50°C for 8 hours to form a colloid.

[0029] After granulation, drying, crushing, and sieving of the colloid, polyacrylamide product is obtained.

[0030] Polyacrylamide molecular weight: 15.5 million.

[0031] Example 3 Dissolve 95g acrylamide, 30g 2-acrylamide-2-methylpropanesulfonic acid, and 4g ethylene glycol in 370g deionized water and stir until completely dissolved.

[0032] Then add 8g of dodecyl acrylate and stir at high speed for 30 minutes (800 rpm) until the solution is homogeneous and transparent. Add 0.03g of EDTA-2Na and 0.05g of N-octylbisacrylamide and stir until homogeneous.

[0033] Nitrogen gas was introduced for 30 minutes to remove oxygen. 0.04 g of ammonium persulfate and 0.03 g of ferrous ammonium sulfate were added to initiate polymerization. The reaction was carried out at 60°C for 6 hours to form a colloid.

[0034] After granulation, drying, crushing, and sieving of the colloid, polyacrylamide product is obtained.

[0035] Polyacrylamide molecular weight: 13.5 million.

[0036] Performance testing Example 1, Example 2, and commercially available PAM were used to treat two typical types of sludge in the papermaking industry: pulping sludge (coniferous wood) and papermaking wastewater sludge.

[0037] The specific parameters of the sludge are shown in Table 1 below.

[0038] Table 1. Sludge parameters before treatment

[0039] Sludge dewatering was carried out using a plate and frame filter press. The basic experimental conditions were as follows: PAM dosage 15 mg / L, stirring mode "fast (300 rpm, 1 min) - medium speed (150 rpm, 3 min) - slow speed (50 rpm, 5 min)", and filtration time 30 min (plate and frame) / 15 min (belt).

[0040] Test indicators: Moisture content of mud cake (gravimetric method GB / T 24188-2009), COD removal rate (potassium dichromate method HJ828-2017), floc strength (compressive strength measured by universal testing machine).

[0041] The various test indicators of the treated sludge are shown in Table 2.

[0042] Table 2. Detection indicators after sludge treatment

[0043] As can be seen from the test results, the hydrophobic modified polyacrylamide of the present invention can effectively target the characteristics of papermaking sludge, achieve good flocculation effect, and effectively treat papermaking sludge.

[0044] 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 hydrophobically modified polyacrylamide for deep dewatering of papermaking sludge, characterized in that, The product comprises the following components by weight: 95-105 parts acrylamide, 20-30 parts 2-acrylamido-2-methylpropanesulfonic acid, 4-6 parts ethylene glycol, 8-12 parts dodecyl acrylate, 0.03-0.06 parts EDTA-2Na, 0.05-0.1 parts N-octylbisacrylamide, 0.03-0.04 parts ammonium persulfate, 0.025-0.035 parts ferrous ammonium sulfate, and 370-380 parts deionized water.

2. The hydrophobically modified polyacrylamide according to claim 1, characterized in that, The hydrophobically modified polyacrylamide comprises the following components by weight: 100 parts acrylamide, 20 parts 2-acrylamide-2-methylpropanesulfonic acid, 5 parts ethylene glycol, 10 parts dodecyl acrylate, 0.05 parts EDTA-2Na, 0.1 parts N-octylbisacrylamide, 0.04 parts ammonium persulfate, 0.035 parts ferrous ammonium sulfate, and 375 parts deionized water.

3. The hydrophobically modified polyacrylamide according to claim 1, characterized in that, The hydrophobically modified polyacrylamide comprises the following components by weight: 105 parts acrylamide, 205 parts 2-acrylamide-2-methylpropanesulfonic acid, 6 parts ethylene glycol, 12 parts dodecyl acrylate, 0.06 parts EDTA-2Na, 0.08 parts N-octylbisacrylamide, 0.03 parts ammonium persulfate, 0.025 parts ferrous ammonium sulfate, and 380 parts deionized water.

4. The hydrophobically modified polyacrylamide according to claim 1, characterized in that, The hydrophobically modified polyacrylamide comprises the following components by weight: 95-100 parts acrylamide, 30 parts 2-acrylamide-2-methylpropanesulfonic acid, 4 parts ethylene glycol, 8 parts dodecyl acrylate, 0.03 parts EDTA-2Na, 0.05 parts N-octylbisacrylamide, 0.04 parts ammonium persulfate, 0.03 parts ferrous ammonium sulfate, and 370 parts deionized water.

5. The hydrophobically modified polyacrylamide according to any one of claims 1 to 4, characterized in that, The hydrophobic modified polyacrylamide has a molecular weight of 13.5-15.5 million.

6. A method for preparing hydrophobically modified polyacrylamide as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Dissolve acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, and ethylene glycol in deionized water and stir until completely dissolved. S2. Add dodecyl acrylate and stir until the solution is homogeneous and transparent. Add EDTA-2Na and N-octylbisacrylamide and stir until homogeneous. S3. Introduce nitrogen gas to purge oxygen. Add ammonium persulfate and ferrous ammonium sulfate to initiate polymerization. React at 50-60℃ for 5-8 hours to form a colloid. S4. After granulation, drying, crushing and sieving of the colloid, the hydrophobic modified polyacrylamide is obtained.

7. The method according to claim 6, characterized in that, In step S2, nitrogen gas is introduced for 30 minutes.

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