Temperature-resistant and salt-resistant polyacrylamide flocculant as well as preparation method and application thereof

Abstract

The invention discloses a temperature-resistant and salt-resistant polyacrylamide flocculant, a preparation method and application, the preparation method of the temperature-resistant and salt-resistant polyacrylamide flocculant comprises the following steps: S1, dissolving acrylamide and a cationic monomer in deionized water, and uniformly stirring to obtain a mixed solution A; s2, adding urea and dimethylaminoethyl methacrylate into the mixed solution A in the S1, and uniformly mixing to obtain a polymerization solution; s3, adding a functional monomer into the polymerization solution in the S2, and uniformly mixing to obtain a mixed solution B; and S4, adding an initiator into the mixed solution B obtained in S3, carrying out a polymerization reaction, cooling, neutralizing, filtering and drying after the reaction to obtain the temperature-resistant and salt-resistant polyacrylamide flocculant. The temperature-resistant and salt-resistant polyacrylamide flocculant prepared by the preparation method disclosed by the invention has good temperature-resistant and salt-resistant performance as a flocculant.

Description

Technical Field

[0001] The invention relates to the technical field of polyacrylamide, and in particular to a temperature-resistant and salt-resistant polyacrylamide flocculant, a preparation method and an application thereof. Background Art

[0002] Polyacrylamide is a polymer material commonly used in sewage treatment, papermaking, oil extraction and other fields. It has good flocculation and thickening properties. At present, the synthesis methods of polyacrylamide flocculants mainly include:

[0003] (1) Free radical copolymerization method: This method is the most common method for synthesizing polyacrylamide flocculants, which is mainly prepared by copolymerization of acrylamide (AM) with cationic monomers such as dimethyldiallylammonium chloride (DMC) and methacryloyloxyethyltrimethylammonium chloride (DMC).

[0004] (2) Emulsion polymerization: This method is to generate polyacrylamide flocculants by free radical initiation of monomer polymerization in oil-water emulsion in the presence of emulsifier and water phase.

[0005] (3) Grafting method: This method is to graft cationic monomers (such as DMC, etc.) onto the acrylamide chain through chemical reaction to achieve cationicization.

[0006] (4) Modification method: This method is to perform post-cationization modification on the synthesized polyacrylamide through chemical reaction. Commonly used modification reagents include dimethylamine, trimethylamine, etc.

[0007] (5) Template method: This method uses hydrogen bonds, electrostatic forces, and van der Waals forces between template molecules and oppositely charged monomers to guide the monomers to arrange in an orderly manner during the polymerization process, thereby generating a polyacrylamide flocculant with a uniform structure. This method can form polymers with a microblock structure.

[0008] Current polyacrylamide flocculants have certain limitations when treating oily wastewater. For example, oily wastewater (such as oil extraction wastewater, etc.) is accompanied by high salt content and high temperature. Existing polyacrylamide flocculants in high salt environments will cause the charge shielding effect of polyacrylamide, reducing its ability to bind to negatively charged suspended particles; in addition, high temperature environments will also cause the molecular weight of polyacrylamide flocculants to decrease, thereby affecting the flocculation effect.

[0009] Therefore, there is an urgent need to develop a polyacrylamide flocculant suitable for high-salt and high-temperature environments. Summary of the invention

[0010] Based on the technical problems existing in the background technology, the present invention proposes a heat-resistant and salt-resistant polyacrylamide flocculant, a preparation method and an application thereof. The prepared heat-resistant and salt-resistant polyacrylamide flocculant has excellent heat-resistant and salt-resistant properties.

[0011] The preparation method of the temperature-resistant and salt-resistant polyacrylamide flocculant proposed by the present invention comprises the following steps:

[0012] S1: dissolving acrylamide and cationic monomer in deionized water, and stirring to obtain a mixed solution A;

[0013] S2: adding urea and dimethylaminoethyl methacrylate to the mixed solution A of S1, and mixing them evenly to obtain a polymer solution;

[0014] S3: adding functional monomers to the polymer solution of S2 and mixing them evenly to obtain a mixed solution B;

[0015] S4: adding an initiator to the mixed solution B in S3 to carry out polymerization reaction, cooling, neutralizing, filtering and drying after the reaction to obtain a temperature-resistant and salt-resistant polyacrylamide flocculant.

[0016] Preferably, the cationic monomer is composed of methacryloyloxyethyl trimethyl ammonium chloride and diallyl dimethyl ammonium chloride in a mass ratio of 3:1-9; and the added amount of the cationic monomer is 30-50% of the mass of acrylamide.

[0017] Preferably, the functional monomer is composed of 2-acrylamide-2-methylpropanesulfonic acid and methacryloyloxyethylmethoxydimethylsilane in a mass ratio of 3:1-9; and the added amount of the functional monomer is 20-40% of the mass of acrylamide.

[0018] Preferably, the mass ratio of acrylamide, urea and dimethylaminoethyl methacrylate is 1000:1-3:0.1-1.

[0019] Preferably, the initiator is one or more of ammonium persulfate, azobisisobutyronitrile, sodium persulfate, and potassium persulfate; and the added amount of the initiator is 0.01-0.1% of the mass of acrylamide.

[0020] Preferably, the initial temperature before the polymerization reaction in S4 is 0-10°C, and the temperature during the polymerization reaction is controlled at 50-70°C and maintained for 3-7h.

[0021] The invention provides a temperature-resistant and salt-resistant polyacrylamide flocculant prepared by the method.

[0022] The invention provides an application of the temperature-resistant and salt-resistant polyacrylamide flocculant in sewage treatment.

[0023] Beneficial technical effects of the present invention:

[0024] (1) The present invention uses the synergistic effect of the quaternary ammonium salt structure of methacryloyloxyethyltrimethylammonium chloride and diallyldimethylammonium chloride and the sulfonic acid group of 2-acrylamide-2-methylpropane sulfonic acid to enable the polymer to maintain a high cation density in a high-salt environment and enhance adsorption and flocculation capabilities; in addition, the sulfonic acid group of 2-acrylamide-2-methylpropane sulfonic acid can also enhance the hydrophilicity and ionic structure of the polymer, which can further improve the stability of the polymer in a high-salt environment.

[0025] (2) The 2-acrylamide-2-methylpropane sulfonic acid of the present invention can introduce a rigid cyclic structure and a sulfonic acid group with strong thermal stability into the polymer chain, thereby improving the thermal stability of the polymer and preventing the polymer from being hydrolyzed or degraded at high temperatures. At the same time, the quaternary ammonium salt structure of diallyldimethylammonium chloride can increase the rigidity of the molecular chain and further improve the high temperature resistance.

[0026] (3) The methacryloxyethylmethoxydimethylsilane of the present invention can improve the adsorption and bridging function of the polymer, thereby improving the flocculation effect of the polymer. DETAILED DESCRIPTION

[0027] The present invention will be further explained below in conjunction with specific embodiments.

[0028] Example 1

[0029] The preparation method of the temperature-resistant and salt-resistant polyacrylamide flocculant proposed by the present invention comprises the following steps:

[0030] S1: dissolving acrylamide and cationic monomer in deionized water, and stirring to obtain a mixed solution A;

[0031] S2: adding urea and dimethylaminoethyl methacrylate to the mixed solution A of S1, and mixing them evenly to obtain a polymer solution;

[0032] S3: adding functional monomers to the polymer solution of S2 and mixing them evenly to obtain a mixed solution B;

[0033] S4: adding an initiator to the mixed solution B in S3 to carry out polymerization reaction, cooling, neutralizing, filtering and drying after the reaction to obtain a temperature-resistant and salt-resistant polyacrylamide flocculant.

[0034] The cationic monomer is composed of methacryloyloxyethyl trimethyl ammonium chloride and diallyl dimethyl ammonium chloride in a mass ratio of 1:1; and the added amount of the cationic monomer is 40% of the mass of acrylamide.

[0035] The functional monomer is composed of 2-acrylamide-2-methylpropanesulfonic acid and methacryloyloxyethylmethoxydimethylsilane in a mass ratio of 1:1; and the added amount of the functional monomer is 30% of the mass of acrylamide.

[0036] The mass ratio of acrylamide, urea and dimethylaminoethyl methacrylate is 1000:2:0.5.

[0037] The initiator is one or more of ammonium persulfate, azobisisobutyronitrile, sodium persulfate and potassium persulfate; the added amount of the initiator is 0.05% of the mass of acrylamide.

[0038] The initial temperature before the polymerization reaction in S4 was 5°C, and the temperature during the polymerization reaction was controlled at 60°C and maintained for 5 hours.

[0039] Example 2

[0040] The preparation method of the temperature-resistant and salt-resistant polyacrylamide flocculant proposed by the present invention comprises the following steps:

[0041] S1: dissolving acrylamide and cationic monomer in deionized water, and stirring to obtain a mixed solution A;

[0042] S2: adding urea and dimethylaminoethyl methacrylate to the mixed solution A of S1, and mixing them evenly to obtain a polymer solution;

[0043] S3: adding functional monomers to the polymer solution of S2 and mixing them evenly to obtain a mixed solution B;

[0044] S4: adding an initiator to the mixed solution B in S3 to carry out polymerization reaction, cooling, neutralizing, filtering and drying after the reaction to obtain a temperature-resistant and salt-resistant polyacrylamide flocculant.

[0045] The cationic monomer is composed of methacryloyloxyethyl trimethyl ammonium chloride and diallyl dimethyl ammonium chloride in a mass ratio of 3:1; and the added amount of the cationic monomer is 30% of the mass of acrylamide.

[0046] The functional monomer is composed of 2-acrylamide-2-methylpropanesulfonic acid and methacryloyloxyethylmethoxydimethylsilane in a mass ratio of 3:1; and the added amount of the functional monomer is 20% of the mass of acrylamide.

[0047] The mass ratio of acrylamide, urea and dimethylaminoethyl methacrylate is 1000:1:0.1.

[0048] The initiator is one or more of ammonium persulfate, azobisisobutyronitrile, sodium persulfate and potassium persulfate; the added amount of the initiator is 0.01% of the mass of acrylamide.

[0049] The initial temperature before the polymerization reaction in S4 was 2°C, and the temperature during the polymerization reaction was controlled at 50°C and maintained for 7 hours.

[0050] Example 3

[0051] The preparation method of the temperature-resistant and salt-resistant polyacrylamide flocculant proposed by the present invention comprises the following steps:

[0052] S1: dissolving acrylamide and cationic monomer in deionized water, and stirring to obtain a mixed solution A;

[0053] S2: adding urea and dimethylaminoethyl methacrylate to the mixed solution A of S1, and mixing them evenly to obtain a polymer solution;

[0054] S3: adding functional monomers to the polymer solution of S2 and mixing them evenly to obtain a mixed solution B;

[0055] S4: adding an initiator to the mixed solution B in S3 to carry out polymerization reaction, cooling, neutralizing, filtering and drying after the reaction to obtain a temperature-resistant and salt-resistant polyacrylamide flocculant.

[0056] The cationic monomer is composed of methacryloyloxyethyl trimethyl ammonium chloride and diallyl dimethyl ammonium chloride in a mass ratio of 1:3; and the added amount of the cationic monomer is 50% of the mass of acrylamide.

[0057] The functional monomer is composed of 2-acrylamide-2-methylpropanesulfonic acid and methacryloyloxyethylmethoxydimethylsilane in a mass ratio of 1:3; and the added amount of the functional monomer is 40% of the mass of acrylamide.

[0058] The mass ratio of acrylamide, urea and dimethylaminoethyl methacrylate is 1000:3:1.

[0059] The initiator is one or more of ammonium persulfate, azobisisobutyronitrile, sodium persulfate and potassium persulfate; the added amount of the initiator is 0.1% of the mass of acrylamide.

[0060] The initial temperature before the polymerization reaction in S4 was 10°C, and the temperature during the polymerization reaction was controlled at 70°C and maintained for 3 hours.

[0061] Comparative Example 1

[0062] The cationic monomer of this embodiment is methacryloyloxyethyl trimethyl ammonium chloride, and the other conditions are the same as those in Example 1.

[0063] Comparative Example 2

[0064] The cationic monomer of this embodiment is diallyldimethylammonium chloride, and the other conditions are the same as those in Example 1.

[0065] Comparative Example 3

[0066] The functional monomer of this solution is methacryloxyethylmethoxydimethylsilane, and the other conditions are the same as those in Example 1.

[0067] Comparative Example 4

[0068] The functional monomer of this solution is 2-acrylamide-2-methylpropanesulfonic acid, and the other conditions are the same as those in Example 1.

[0069] Taking a certain oilfield wastewater as an example, the performance of the heat-resistant and salt-resistant polyacrylamide flocculants prepared in Examples 1-3 and Comparative Examples 1-4 was measured, and the test results are shown in Table 1. Among them:

[0070] The method for determining turbidity and COD content is as follows: add 5 mg / L of heat-resistant and salt-resistant polyacrylamide flocculant to oilfield wastewater (COD is 2143.6 mg / L, turbidity is 805.7 NTU) at 60°C and 90°C, respectively. After standing for 15 minutes, aspirate the upper clarified liquid to determine the turbidity and COD content.

[0071] Table 1 Flocculant performance test results

[0072]

[0073] It can be seen from the test results of Examples 1-3 in Table 1 that the heat-resistant and salt-resistant polyacrylamide flocculant prepared by the present invention has good high temperature and high salt resistance, and the COD of oilfield wastewater after treatment is less than 50 mg / L. The test results of Example 1 and Comparative Examples 1-3 illustrate that methacryloyloxyethyl trimethyl ammonium chloride, diallyl dimethyl ammonium chloride and 2-acrylamide-2-methyl propane sulfonic acid have a synergistic effect on improving the salt resistance of the flocculant. This is because the quaternary ammonium salt structure of methacryloyloxyethyl trimethyl ammonium chloride and diallyl dimethyl ammonium chloride and the sulfonic acid group of 2-acrylamide-2-methyl propane sulfonic acid synergistically enable the polymer to maintain a high cation density in a high salt environment and enhance the adsorption and flocculation ability; in addition, the sulfonic acid group of 2-acrylamide-2-methyl propane sulfonic acid can also enhance the hydrophilicity of the polymer and the ionic structure can further improve the stability of the polymer in a high salt environment. It can be seen from the test results of Example 1, Comparative Example 1 and Comparative Example 3 that 2-acrylamide-2-methylpropane sulfonic acid and diallyldimethylammonium chloride have a greater influence on the high temperature resistance of the flocculant, because 2-acrylamide-2-methylpropane sulfonic acid can introduce a rigid ring structure and a sulfonic acid group with strong thermal stability into the polymer chain, thereby improving the thermal stability of the polymer and preventing the polymer from being hydrolyzed or degraded at high temperatures, and at the same time, the quaternary ammonium salt structure of diallyldimethylammonium chloride can increase the rigidity of the molecular chain, further improving the high temperature resistance. It can be seen from the test results of Example 1 and Comparative Example 4 that the methacryloxyethylmethoxydimethylsilane of the present invention also has a greater influence on the flocculation effect of the flocculant, because the methacryloxyethylmethoxydimethylsilane can improve the adsorption and bridging function of the polymer, thereby improving the flocculation effect of the polymer.

Claims

1. A method for preparing a heat-resistant and salt-resistant polyacrylamide flocculant, characterized in that: The steps are as follows: S1: dissolving acrylamide and cationic monomer in deionized water, and stirring to obtain a mixed solution A; S2: adding urea and dimethylaminoethyl methacrylate to the mixed solution A of S1, and mixing them evenly to obtain a polymer solution; S3: adding functional monomers to the polymer solution of S2 and mixing them evenly to obtain a mixed solution B; S4: adding an initiator to the mixed solution B in S3 to carry out polymerization reaction, cooling, neutralizing, filtering and drying after the reaction to obtain a temperature-resistant and salt-resistant polyacrylamide flocculant.

2. The method for preparing the heat-resistant and salt-resistant polyacrylamide flocculant according to claim 1, characterized in that: The cationic monomer is composed of methacryloyloxyethyl trimethyl ammonium chloride and diallyl dimethyl ammonium chloride in a mass ratio of 3:1-9; the added amount of the cationic monomer is 30-50% of the mass of acrylamide.

3. The method for preparing the heat-resistant and salt-resistant polyacrylamide flocculant according to claim 1, characterized in that: The functional monomer is composed of 2-acrylamide-2-methylpropanesulfonic acid and methacryloyloxyethylmethoxydimethylsilane in a mass ratio of 3:1-9; the added amount of the functional monomer is 20-40% of the mass of acrylamide.

4. The method for preparing the heat-resistant and salt-resistant polyacrylamide flocculant according to claim 1, characterized in that: The mass ratio of acrylamide, urea and dimethylaminoethyl methacrylate is 1000:1-3:0.1-1.

5. The method for preparing the heat-resistant and salt-resistant polyacrylamide flocculant according to claim 1, characterized in that: The initiator is one or more of ammonium persulfate, azobisisobutyronitrile, sodium persulfate and potassium persulfate; the added amount of the initiator is 0.01-0.1% of the mass of acrylamide.

6. The method for preparing the heat-resistant and salt-resistant polyacrylamide flocculant according to claim 1, characterized in that: The initial temperature before the polymerization reaction in S4 is 0-10°C, and the temperature during the polymerization reaction is controlled at 50-70°C and maintained for 3-7h.

7. A temperature-resistant and salt-resistant polyacrylamide flocculant prepared by the method according to any one of claims 1 to 6.

8. Use of the temperature-resistant and salt-resistant polyacrylamide flocculant as claimed in claim 7 in sewage treatment.

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