1,1,2,2-tetrahydroperfluoroalkyl substituted allyl quaternary ammonium salts, processes for their preparation and use

Abstract

This invention relates to a 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt, its preparation method, and its application, belonging to the field of flocculation treatment technology for high-salt industrial wastewater from natural gas purification. To address the problem that the synthesis of cationic polymer flocculants in existing technologies requires large amounts of surfactants and involves complex operations, this application employs a substitution reaction between 1,1,2,2-tetrahydroperfluoroalkyl iodide and N-methylallylamine; iodomethane is then reacted with the substitution reaction product to undergo quaternization, yielding a 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt; the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt is polymerized with acrylamide to obtain a novel cationic polyacrylamide flocculant. The synthesis of cationic fluorocarbon-modified hydrophobic associative polyacrylamide flocculants using an aqueous solution polymerization method is simple, requires no surfactants, and experiments show that the prepared flocculant exhibits excellent flocculation performance.

Description

Technical Field

[0001] This invention belongs to the field of flocculation treatment technology for high-salt industrial wastewater from natural gas purification, specifically relating to a 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt, its preparation method, and its application. Background Technology

[0002] Flocculation and sedimentation water treatment methods have significant advantages such as simple process, ease of operation, low investment, low energy consumption, and low operating costs, and are widely used in urban sewage and industrial wastewater treatment. Currently, cationic polyacrylamide, as a water-soluble polymer, is widely used in flocculation and sedimentation water treatment for domestic sewage and industrial wastewater due to its excellent thickening, dissolving, and filtration capabilities, making it an important class of cationic polymer flocculants. However, for high-salinity industrial wastewater from natural gas purification, traditional cationic polyacrylamide flocculants exhibit poor flocculation and sedimentation treatment effects due to the high salinity factor.

[0003] In recent years, cationic fluorocarbon-modified hydrophobically associating polyacrylamide flocculants have attracted widespread attention. They utilize the charge compensation, hydrophobic association, and bridging effects of acrylamide, cationic monomers, and fluorinated hydrophobic monomers in copolymers to achieve a synergistic flocculation effect. Because fluorine atoms are very difficult to polarize and the polarity of fluorocarbon chains is much lower than that of hydrocarbon chains, fluorocarbon-type hydrophobic monomer polymers exhibit stronger intermolecular association compared to traditional hydrocarbon-chain hydrophobic monomer polymers. Specifically, based on the hydrophobic association effect, cationic fluorocarbon-modified hydrophobically associating polyacrylamide flocculant molecules adsorb onto suspended particles in high-salinity industrial wastewater in different forms (such as tail-like, cyclic, and random coils), thereby improving charge neutralization efficiency, promoting bridging, and enhancing flocculation. Therefore, they exhibit excellent effects in the flocculation and sedimentation treatment of high-salinity industrial wastewater.

[0004] Current literature reports the use of nonionic fluorinated hydrophobic monomers such as trifluoroethyl methacrylate and hexafluorobutyl methacrylate to synthesize cationic polymer flocculants via free radical micellar polymerization. However, this method requires the extensive use of surfactants and the synthesis process is relatively complex. Summary of the Invention

[0005] To address the aforementioned technical problems and improve the flocculation effect of existing flocculants, this invention provides a cationic polyacrylamide flocculant synthesized from a 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt and acrylamide. This flocculant achieves the goal of synthesizing cationic fluorocarbon-modified hydrophobic associative polyacrylamide flocculants using an aqueous solution polymerization method with cationic fluorinated hydrophobic monomers, avoiding the extensive use of surfactants and simplifying the synthesis process.

[0006] Specifically, this is achieved through the following technical solution:

[0007] A method for preparing a cationic polyacrylamide flocculant specifically includes the following steps:

[0008] Step 1: 1,1,2,2-Tetrahydroperfluoroalkyliodide reacts with N-methylallylamine in the presence of an acid-binding agent and an organic solvent in a substitution reaction, wherein the 1,1,2,2-tetrahydroperfluoroalkyliodide is selected from one of 1,1,2,2-tetrahydroperfluorobutyliodide, 1,1,2,2-tetrahydroperfluoropentyliodide, or 1,1,2,2-tetrahydroperfluorohexyliodide.

[0009]

[0010] Specifically, the acid-binding agent is selected from at least one of sodium carbonate or potassium carbonate;

[0011] Specifically, the organic solvent is selected from at least one of dichloromethane, chloroform, or diethyl ether;

[0012] Specifically, in molar ratio, the ratio of 1,1,2,2-tetrahydroperfluoroalkyl iodine: N-methylallylamine: organic solvent: acid-binding agent is 1:1 to 1.5:4-6:2-3;

[0013] Specifically, the substitution reaction temperature is 25-30℃, and the reaction time is 5-8h.

[0014] Step 2: Iodomethane reacts with the above substitution reaction product in a quaternization reaction to obtain a 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt, wherein the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt is selected from 1,1,2,2-tetrahydroperfluorobutyl-substituted allyl quaternary ammonium salt, 1,1,2,2-tetrahydroperfluoropentyl-substituted allyl quaternary ammonium salt, or 1,1,2,2-tetrahydroperfluorohexyl-substituted allyl quaternary ammonium salt.

[0015]

[0016] Where n = 1, 2 or 3;

[0017] Specifically, the molar ratio of iodomethane to 1,1,2,2-tetrahydroperfluoroalkyl iodine is 2-4:1;

[0018] Specifically, the quaternization reaction is carried out at a temperature of 40-50℃ for a duration of 10-15 hours.

[0019] Step 3: Add the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt and acrylamide to water at a molar ratio of 1:95-99 to obtain a monomer solution with a mass fraction of 20-30 wt.%.

[0020] A polymerization reaction occurs to obtain cationic polyacrylamide flocculant.

[0021] The pH of the monomer solution was controlled at 7.5±0.5; nitrogen gas was then introduced, and the monomer solution was heated and the temperature was controlled at 40-45℃; then an initiator with a mass ratio of sodium persulfate to sodium sulfite of 2-3:1 was added, and the amount of initiator added was 0.2-0.3 wt.% of the total mass of monomer; the polymerization reaction was carried out in a polymerization reactor for 6-9 hours; the product was taken out, washed, dried and ground into powder to obtain cationic polyacrylamide flocculant.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The present invention can produce the following beneficial effects:

[0024] (1) To enrich the types of fluorinated hydrophobic monomers, a 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt and its preparation method are provided, resulting in a new type of fluorinated cationic hydrophobic monomer.

[0025] (2) Taking advantage of the surface-active properties of 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salts, cationic fluorocarbon-modified hydrophobic associative polyacrylamide flocculants can be synthesized by aqueous solution polymerization. The operation is simple and does not require the use of surfactants. Attached Figure Description

[0026] Figure 1 Infrared spectrum of 1,1,2,2-tetrahydroperfluorohexyldimethylallyl quaternary ammonium salt prepared in Example 1;

[0027] Figure 2 The 1H NMR spectrum of 1,1,2,2-tetrahydroperfluorohexyldimethylallyl quaternary ammonium salt prepared in Example 1;

[0028] Figure 3 The permeability of the supernatant after flocculation and sedimentation of diatomaceous earth suspension (containing 4% sodium chloride) simulating high-salt wastewater under different polymer flocculant dosages was determined. Detailed Implementation

[0029] Example 1

[0030] Preparation of 1,1,2,2-tetrahydroperfluorobutyldimethylallyl quaternary ammonium salt:

[0031] 1 mol of N-methylallylamine and 1 mol of 1,1,2,2-tetrahydroperfluorobutyl iodide were added to a round-bottom three-necked flask, followed by the addition of 5 times the equivalent of 1,1,2,2-tetrahydroperfluorobutyl iodide in dichloromethane as a solvent. The mixture was dissolved by stirring at 200 rpm, and then 2 times the equivalent of 1,1,2,2-tetrahydroperfluorobutyl iodide in potassium carbonate was added as an acid-binding agent. The reaction was carried out at 25°C for 8 hours. After this step, 2 times the equivalent of 1,1,2,2-tetrahydroperfluorobutyl iodide in iodomethane was added dropwise, followed by reflux at 40°C for 12 hours. Finally, the solvent and excess iodomethane were removed by vacuum distillation to obtain the target product, 1,1,2,2-tetrahydroperfluorobutyldimethylallyl quaternary ammonium salt, with a critical micelle concentration (cmc) of 0.10 mol / L. The corresponding surface tension at the critical micelle concentration was 39.8 mN / m, indicating good surface activity.

[0032] like Figure 1 As shown in the infrared spectrum of the 1,1,2,2-tetrahydroperfluorohexyl-substituted allyl quaternary ammonium salt prepared in Example 1, it can be seen that: 3448 cm⁻¹ -1 The peak is water, indicating that the sample has a certain degree of water solubility; 3006 cm⁻¹ -1 The stretching vibration of the CH double bond; 2958 cm⁻¹ -1 2927cm -1 and 2723cm -1 CH stretching vibration of methyl and methylene groups; 1633 cm⁻¹ -1 The C=C stretching vibration of the double bond; 1238 cm⁻¹ -1 and 1201cm -1 It is a CF stretching vibration.

[0033] like Figure 2 As shown, the 1H NMR spectrum of the 1,1,2,2-tetrahydroperfluorohexyl-substituted allyl quaternary ammonium salt prepared in Example 1 shows the following: the three peaks at 5.63-6.09 ppm are protons of the double bond CH2=CH-; the peak at 4.02 ppm is the proton of the methylene group attached to the double bond CH2=CH-CH2-; the peak at 3.45 ppm is the proton of the methyl group attached to the N-methyl group CH3-N; and the peak at 3.32 ppm is the proton of the methylene group attached to the N-methyl group N-CH2-CH2-C. n F 2n+1 The peak at 3.12 ppm represents the proton of the methylene group attached to the nitrogen atom (N-CH2-CH2-C). n F 2n+1 .

[0034] Example 2

[0035] Preparation of 1,1,2,2-tetrahydroperfluoropentyldimethylallyl quaternary ammonium salt:

[0036] 1.2 mol of N-methylallylamine and 1 mol of 1,1,2,2-tetrahydroperfluoropentyliodide were added to a round-bottom three-necked flask, followed by the addition of chloroform (6 times the equivalent of 1,1,2,2-tetrahydroperfluoropentyliodide) as a solvent. The mixture was dissolved by stirring at 200 rpm, and then sodium carbonate (3 times the equivalent of 1,1,2,2-tetrahydroperfluoropentyliodide) was added as an acid-binding agent. The reaction was carried out at 28 °C for 6 hours. After this step, iodomethane (3 times the equivalent of 1,1,2,2-tetrahydroperfluoropentyliodide) was added dropwise, followed by reflux at 45 °C for 10 hours. Finally, the solvent and excess iodomethane were removed by vacuum distillation to obtain the target product, 1,1,2,2-tetrahydroperfluoropentyldimethylallyl quaternary ammonium salt, with a critical micelle concentration (cmc) of 0.08 mol / L. The surface tension corresponding to the critical micelle concentration is 38.2 mN / m, indicating good surface activity.

[0037] Example 3

[0038] Preparation of 1,1,2,2-tetrahydroperfluorohexyldimethylallyl quaternary ammonium salt:

[0039] 1.5 mol of N-methylallylamine and 1 mol of 1,1,2,2-tetrahydroperfluorohexyl iodine were added to a round-bottom three-necked flask, followed by the addition of diethyl ether (equivalent to 1,1,2,2-tetrahydroperfluorohexyl iodine) as a solvent. The mixture was dissolved by stirring at 250 rpm, and then sodium carbonate (equivalent to 1,1,2,2-tetrahydroperfluorohexyl iodine) was added as an acid-binding agent. The reaction was carried out at 30 °C for 6 hours. After this step, iodomethane (equivalent to 1,1,2,2-tetrahydroperfluorohexyl iodine) was added dropwise, followed by reflux at 50 °C for 10 hours. Finally, the solvent and excess iodomethane were removed by vacuum distillation to obtain the target product, 1,1,2,2-tetrahydroperfluorohexyldimethylallyl quaternary ammonium salt, with a critical micelle concentration (cmc) of 0.07 mol / L. The corresponding surface tension at the critical micelle concentration was 37.4 mN / m, indicating good surface activity.

[0040] Example 4

[0041] Synthetic cationic polyacrylamide flocculant:

[0042] A certain amount of deionized water was added to the polymerization reactor. The 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salts prepared in Examples 1-3 were stirred and reacted with acrylamide. The mass fraction of the monomer solution was controlled at 20 wt.%, and the molar ratio of 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salts to acrylamide was controlled at 1:99. The pH of the monomer solution was then controlled at 7.5. Nitrogen gas was then introduced for 30 minutes, and the monomer solution was heated and the temperature was controlled at 45°C. Sodium persulfate and sodium sulfite initiators were then added in a mass ratio of 2:1, with the initiator amount being 0.2 wt.% of the total monomer mass. The polymerization reaction was carried out in the polymerization reactor for 6 hours. Finally, the product was taken out, washed multiple times with ethanol, and the washed product was dried in a vacuum oven at 55°C to constant weight and ground into powder to obtain cationic polyacrylamide flocculant.

[0043] Example 5

[0044] Synthetic cationic polyacrylamide flocculant:

[0045] A certain amount of deionized water was added to the polymerization reactor. The 1,1,2,2-tetrahydroperfluorobutyl-substituted allyl quaternary ammonium salt prepared in Example 1 was stirred and reacted with acrylamide. The mass fraction of the monomer solution was controlled at 30 wt.%, and the molar ratio of 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt to acrylamide was controlled at 1:95. The pH of the monomer solution was then controlled at 8.0. Nitrogen gas was then introduced for 30 minutes, and the monomer solution was heated and controlled to 40°C. Sodium persulfate and sodium sulfite initiators were then added in a mass ratio of 2:1, with the initiator amount being 0.3 wt.% of the total monomer mass. The polymerization reaction was carried out in the polymerization reactor for 9 hours. Finally, the product was taken out, washed multiple times with ethanol, and the washed product was dried in a vacuum oven at 55°C to constant weight and ground into powder to obtain cationic polyacrylamide flocculant.

[0046] Experimental Example 1

[0047] In Example 4, the cationic polyacrylamide flocculant formed by polymerizing the 1,1,2,2-tetrahydroperfluorobutyldimethylallyl quaternary ammonium salt monomer prepared in Example 1 is designated as Example 1; the cationic polyacrylamide flocculant formed by polymerizing the 1,1,2,2-tetrahydroperfluoropentyldimethylallyl quaternary ammonium salt monomer prepared in Example 2 is designated as Example 2; and the cationic polyacrylamide flocculant formed by polymerizing the 1,1,2,2-tetrahydroperfluorohexyldimethylallyl quaternary ammonium salt monomer prepared in Example 3 is designated as Example 3. Examples 1 to 3 were used to simulate the flocculation treatment of high-salinity wastewater. At 25°C, flocculants of Examples 1, 2, and 3 at different mass concentrations, and a conventional cationic polyacrylamide flocculant (molecular weight 10 million) produced by Chengdu Kelong Chemical Co., Ltd., were added to a diatomaceous earth suspension (containing 4% sodium chloride) to simulate the flocculation treatment of high-salinity wastewater. After thorough stirring and standing, the supernatant was collected, and its transmittance was measured using a spectrophotometer to evaluate the flocculation effect.

[0048] like Figure 3 As shown, under different polymer flocculant dosages, compared with conventional cationic polyacrylamide flocculants, the supernatant transmittance of Examples 1, 2, and 3 can all reach over 90%, indicating that the cationic fluorocarbon-modified hydrophobic associative polyacrylamide flocculant has a significant flocculation and removal effect on diatomaceous earth suspended solids in simulated high-salt wastewater. Moreover, in Example 3, after a dosage of 12 mg / treatment, the transmittance of the corresponding supernatant reached a maximum of 99.8%, indicating a particularly significant flocculation effect.

Claims

1. A 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt, characterized in that, The structural formula of the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt is: Where n = 1, 2 or 3.

2. A method for preparing the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt as described in claim 1, characterized in that, Includes the following steps: 1,1,2,2-Tetrahydroperfluoroalkyliodide undergoes a substitution reaction with N-methylallylamine: Iodomethane reacts with the product of the above substitution reaction to undergo quaternization, yielding 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salts: Where n = 1, 2 or 3.

3. The method for preparing the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt according to claim 2, characterized in that, The substitution reaction is carried out in the presence of an acid-binding agent and an organic solvent.

4. The method for preparing the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt according to claim 3, characterized in that, The acid-binding agent is selected from at least one of sodium carbonate or potassium carbonate.

5. The method for preparing the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt according to claim 3, characterized in that, The organic solvent is selected from at least one of dichloromethane, trichloromethane, or diethyl ether.

6. The method for preparing the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt according to claim 3, characterized in that, The molar ratio of 1,1,2,2-tetrahydroperfluoroalkyl iodine: N-methylallylamine: organic solvent: acid binder is 1:1 to 1.5:4-6:2-3.

7. The method for preparing the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt according to claim 2, characterized in that, The substitution reaction temperature is 25-30℃, and the reaction time is 5-8h.

8. The method for preparing the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt according to claim 2, characterized in that, The molar ratio of iodomethane to 1,1,2,2-tetrahydroperfluoroalkyliodide is 2-4:

1.

9. The method for preparing the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt according to claim 2, characterized in that, The quaternization reaction is carried out at a temperature of 40-50℃ for a duration of 10-15 hours.

10. A cationic polyacrylamide flocculant, characterized in that, It is obtained by polymerization of the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt as described in claim 1 with acrylamide.

11. The cationic polyacrylamide flocculant according to claim 10, characterized in that, The molar ratio of the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt to acrylamide is 1:95-99.

12. The application of the 1,1,2,2-tetrahydroperfluoroalkyl-substituted allyl quaternary ammonium salt as described in claim 1 or the cationic polyacrylamide flocculant as described in claim 10 or 11 in the purification of wastewater.

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