A hydrophobic flocculant, its preparation method and application

Abstract

This invention belongs to the technical field of hydrophobic associative functional polymer compounds, specifically relating to a hydrophobic flocculant, its preparation method, and its application. The hydrophobic flocculant disclosed in this invention comprises adsorption structural units and hydrophobic structural units embedded within a polyacrylamide molecular chain. Based on the adsorption capacity of the adsorption structural units for fine particles, methacrylamidopropyltrimethylammonium chloride is selected as the cationic monomer. Molecular dynamics simulations are used to comprehensively analyze the hydrophobic properties and association characteristics of the hydrophobic structural units, with perfluorohexylethyl methacrylate selected as the hydrophobic monomer. This flocculant exhibits a novel structure, excellent turbidity removal effect, and low reagent residue, demonstrating strong application potential.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydrophobic association functional polymer compounds, and particularly relates to a hydrophobic flocculant and a preparation method and application thereof. BACKGROUND

[0002] With the increasing environmental pollution, the control and treatment of water environmental pollution gradually attract people's attention and make progress in all aspects. There are various ways of water treatment, including ultrasonic treatment, electrodialysis, membrane filtration and centrifugal separation technologies. Among them, the flocculation sedimentation process is simple in operation and low in cost, and is a mature and good wastewater treatment process, which is widely used by water treatment companies at home and abroad.

[0003] Commercial flocculants on the market mainly include cationic, anionic, non-ionic and amphoteric flocculants. Considering that the content of fine particles in wastewater is large, the surface has negative charge, and the electrostatic repulsion between particles leads to difficult treatment of wastewater. The cationic flocculant can neutralize the particles with negative charge by electricity, and accelerate the coagulation of particles and flocculant molecules to form flocs by bridging effect, therefore, the cationic flocculant with high ionic degree is more expected, but the synthesis process of the flocculant with high cationic degree is more complex.

[0004] In addition, for the treatment of beneficiation wastewater, especially for the wet beneficiation and metallurgical industry, due to the decrease of mineral grade and the improvement of separation technology process, the particle size in beneficiation wastewater is continuously reduced, and the hydration effect on the surface of particles gradually becomes significant, the hydration repulsion between particles becomes more intense, leading to the stable suspension of micro-fine or micro-nano scale particles in beneficiation wastewater. In the face of beneficiation wastewater with high content of solid suspensions and good stability, the commercial flocculants on the market do not consider the hydration characteristics of particles, and even enhance the combination of surface and water molecules, leading to the fact that the flocculant cannot stably adsorb micro-fine or micro-nano particles, the turbidity of circulating water is high and the residual amount of reagent is large, which in turn causes a series of problems such as deterioration of circulating water quality, pollution of concentrate products, low utilization rate of tailings and difficulty in stacking, and even causes harm to the ecological environment such as water pollution, soil damage and dust pollution.

[0005] Therefore, it is an urgent need of the market to provide a new type of flocculant suitable for beneficiation wastewater treatment, which has excellent turbidity removal effect and small residual amount of reagent. SUMMARY

[0006] Therefore, the first object of the present application is to provide a hydrophobic flocculant suitable for beneficiation wastewater treatment, which has excellent turbidity removal effect and small residual amount of reagent.

[0007] In order to achieve the above object, the present application adopts the following technical solutions:

[0008] A hydrophobic flocculant comprises adsorption structural units and hydrophobic structural units embedded in polyacrylamide molecular chains, the cationic monomer constituting the adsorption structural units is methyl methacrylamido propyl trimethyl ammonium chloride, and the hydrophobic monomer constituting the hydrophobic structural units is perfluorohexyl ethyl methacrylate.

[0009] It is worth noting that the adsorption structural units in the hydrophobic flocculant have positive charge groups, which not only electrically neutralize the negatively charged particles in wastewater, but also have excellent adsorption capacity, can capture fine or micro-nano particles and promote the aggregation of particles into large flocculation, so as to realize the separation of particles from the suspension. The introduction of the hydrophobic structural units can weaken or break the hydration film on the surface of the particles, promote the stable adsorption of the adsorption structural units on the surface of the particles, in addition, the hydrophobic structural units help the molecular chain of the hydrophobic flocculant to associate and stretch, which not only enhances the bridging performance of the polymer, but also reduces the residual dosage of the flocculant and improves the flocculation treatment effect and the dewatering effect of the flocculation.

[0010] The present application uses perfluorohexyl ethyl methacrylate as a hydrophobic monomer to construct a hydrophobic structural unit, which is selected based on molecular dynamics simulation method. The carbon-fluorine branch on the hydrophobic structural unit has the strongest hydrophobic association performance, which can promote the adsorption of the adsorption structural unit on the surface of fine or micro-nano particles, enhance the bridging mechanism to form larger flocculation, improve the turbidity removal efficiency and settling velocity, and the length of the carbon-fluorine branch is less than 6, which is more easily degradable and reduces pollution to water resources.

[0011] Further, the cationic degree of the copolymer is 10-50%, and the hydrophobic degree is 2.5-17.5%.

[0012] The hydrophobic flocculant disclosed in the present application has stronger adsorption capacity on the surface of fine or micro-nano particles, which enhances the turbidity removal efficiency of the flocculant and reduces the possibility of flocculation breaking and recombination; the hydrophobic structural unit on the flocculant has excellent hydrophobic and association performance, which can break or weaken the hydration on the surface of the particles and enhance the bridging mechanism, reduce the residual dosage of the medicament in wastewater treatment, and promote the pressure filtration dewatering.

[0013] The second object of the present application is to provide a preparation method of the hydrophobic flocculant.

[0014] A preparation method of a hydrophobic flocculant, using acrylamide as the main monomer, methyl methacrylamido propyl trimethyl ammonium chloride as the cationic monomer, and perfluorohexyl ethyl methacrylate as the hydrophobic monomer, the copolymer is polymerized by low-pressure ultraviolet initiation.

[0015] It is worth mentioning that the short wave in the low-pressure ultraviolet (UV) copolymerization reaction adopted by the present application can provide high efficient radiation energy for initiation, a large number of reaction regions centered on the initiation radicals appear, the copolymerization reaction rate is improved, and a porous structure is formed, which is beneficial to reducing the dissolution time of the hydrophobic flocculant and improving the use efficiency of the flocculant in industrial production.

[0016] Further, the preparation method comprises the following specific steps:

[0017] S1, a certain amount of hydrophobic monomer, surfactant and deionized water are mixed, the pH of the reaction system is adjusted to 2.5-5.5, and a transparent solution is obtained after sufficient dispersion, which is used as A liquid;

[0018] S2, a certain amount of acrylamide monomer, cationic monomer and solubilizer are added to the A liquid, nitrogen is introduced throughout the process for protection, and B liquid is obtained after sufficient mixing at room temperature;

[0019] S3, a certain amount of photoinitiator is added to the B liquid, the mixture is mixed thoroughly, and then the mixture is transferred to a light irradiation reaction device;

[0020] S4, after being irradiated by a low-pressure ultraviolet lamp for a certain time, the mixture is solidified at room temperature for 2-4 h to obtain a gel C;

[0021] S5, the gel C is transferred to a mixed solution of ethanol and acetone, and is cut into pieces for sufficient washing to obtain a solid D;

[0022] S6, the solid D is dried for 24 h, and is ground to obtain a finished flocculant.

[0023] Further, the surfactant in the step S1 is cetyltrimethylammonium bromide, the solubilizer in the step S2 is urea, and the photoinitiator in the step S3 is one of azobisdimethylammonium bromide, azobisdiisopropyl imidazole hydrochloride, azobisimidozolinyl propane, irgacure 2959.

[0024] In some embodiments, the photoinitiator is irgacure 2959.

[0025] Further, the total monomer mass of the hydrophobic monomer, the acrylamide monomer and the cationic monomer in the step S2 accounts for 15-45% of the mass of the B liquid, the molar mass of the cationic monomer accounts for 10-50% of the total monomer, and the molar mass ratio of the acrylamide monomer to the hydrophobic monomer is (7.75-6.25):(0.25-1.75).

[0026] Further, the surfactant in step S1 is used in an amount of 1.3-5.3% of the total monomer mass fraction, the solubilizing agent in step S2 is used in an amount of 0.1-0.7% of the total monomer mass fraction, and the photoinitiator in step S3 is used in an amount of 0.01-0.07% of the total monomer mass fraction.

[0027] Further, the low-pressure ultraviolet lamp in step S4 is 24W or 48W, the radiation wavelength is 253.7nm, and the light irradiation reaction time is 2-8h.

[0028] A third object of the present application is to provide an application of the hydrophobic flocculant as described above in wastewater treatment.

[0029] It is worth noting that the hydrophobic flocculant disclosed in the present application is mainly used in the treatment of beneficiation wastewater containing a large amount of fine or micro-nano particles. The particle surface in beneficiation wastewater usually has a strong negative charge, and the smaller the particle size, the stronger the hydration effect on the surface. The electrostatic repulsion and hydration repulsion between particles are the essential reasons for the stable suspension of particles. Therefore, the hydrophobic flocculant disclosed in the present application has adsorption and hydrophobic structural units, which can weaken or break the electrostatic repulsion and hydration repulsion between particles, improve the turbidity removal efficiency, settling speed and dewatering effect, etc., and realize efficient treatment of beneficiation wastewater.

[0030] Compared with the prior art, the hydrophobic flocculant disclosed in the present application is prepared by polymerizing cationic monomers and hydrophobic monomers with acrylamide to form a hydrophobic polyacrylamide, which has low system viscosity and good flocculation effect. The obtained hydrophobic flocculant has excellent turbidity removal effect, low reagent residue, and strong application potential in wastewater treatment. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings

[0032] Figure 1 The reaction equation of the polymerization reaction disclosed in the present application is shown in the following formula.

[0033] Figure 2 The radial water density distribution of the hydrophobic structural unit in Experimental Example 1 of the present application is shown in the following formula.

[0034] Figure 3 The distribution probability of the hydrophobic structural unit R g in Experimental Example 1 of the present application is shown in the following formula.

[0035] Figure 4Adsorption amount of polyacrylamide type flocculant in Example 1 on kaolinite particles and residual amount in aqueous solution, (a) : N682; (b) : A6056; (c) : C6360; (d) : supernatant turbidity.

[0036] Figure 5 Adsorption amount of cationic flocculant (P(AM-MAPTAC)) in Comparative Example 1 on kaolinite surface (a), supernatant turbidity (b).

[0037] Figure 6 Adsorption amount of hydrophobic flocculant (P(AM-MAPTAC-TEMAc6)) in Comparative Example 1 on kaolinite surface (a), supernatant turbidity (b).

[0038] Figure 7 Scanning electron microscope image of hydrophobic flocculant (P(AM-MAPTAC-TEMAc6)) obtained in Example 1.

[0039] Figure 8 Scanning electron microscope image of hydrophobic flocculant (P(AM-MAPTAC-TEMAc6)) obtained in Example 2. 1 HNMR spectrum. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0041] Herein, the term "embodiment" is used as "exemplary" to explain any embodiment, which is not necessarily construed as superior or better than other embodiments. In the performance index test of the embodiments of the present application, unless otherwise specified, the conventional test method in the art is adopted. It should be understood that the terms described in the present application are only used to describe the specific embodiments, and are not used to limit the disclosure of the present application.

[0042] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as generally understood by those of ordinary skill in the art to which the present application belongs; as the test methods and technical means not specially noted in the present application refer to the experimental methods and technical means generally used by those of ordinary skill in the art.

[0043] For a better understanding of the present application, numerous specific details are given in the following detailed description. The present application may, however, be practiced without certain specific details. In an embodiment, some methods, apparatus, instruments, devices, etc. that are well known in the art are not described in detail in order to avoid obscuring the subject matter of the present application.

[0044] The technical features disclosed in the embodiments of the present application can be combined arbitrarily without conflict, and the resulting technical solutions belong to the disclosure of the present application.

[0045] The application discloses a hydrophobic flocculant and a preparation method and application thereof. The hydrophobic flocculant disclosed by the application comprises a cationic structural unit and a hydrophobic structural unit, wherein the cationic structural unit and the hydrophobic structural unit are embedded in a polyacrylamide carbon chain. The hydrophobic performance and the association performance are analyzed by using a molecular dynamics simulation method, and methylacrylamidopropyltrimethylammonium chloride is selected as the cationic monomer, and perfluorohexylethyl methacrylate is selected as the hydrophobic monomer. The flocculant has novel structure, excellent turbidity removal effect, small amount of residual agent, and strong application potential.

[0046] The preparation method disclosed by the application comprises the following specific steps:

[0047] S1, a certain amount of hydrophobic monomers, surfactants and deionized water are mixed, and the pH of the reaction system is adjusted to 2.5-5.5, and a transparent solution is obtained after sufficient dispersion, which is used as A liquid;

[0048] S2, a certain amount of acrylamide monomers, cationic monomers and solubilizers are added to the A liquid, nitrogen is introduced throughout the process, and the mixture is fully mixed at room temperature to obtain B liquid;

[0049] S3, a certain amount of photoinitiator is added to the B liquid, and the mixture is fully mixed, and then the mixture is transferred to a light irradiation reaction device;

[0050] S4, the mixture is irradiated by a low-pressure ultraviolet lamp for a certain time, and then solidified at room temperature for 2-4 hours to obtain a gel C;

[0051] S5, the gel C is transferred to a mixture of ethanol and acetone, and is cut into small pieces, and is fully washed to obtain a solid D;

[0052] S6, the solid D is dried for 24 hours, and is ground to obtain a finished flocculant.

[0053] As an embodiment of the application, the pH value in step S1 includes 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 and 5.5. Preferably, the pH value in step S1 is 4.0.

[0054] Further, the surfactant in step S1 is hexadecyl trimethyl ammonium bromide, the solubilizer in step S2 is urea, and the photoinitiator in step S3 is one of azobisdimethylaminoformate hydrochloride, azobisdimethylpropyl imidazoline hydrochloride, azobisimidozolinyl propane, irgacure 2959.

[0055] As an embodiment of the present application, the photoinitiator is irgacure 2959.

[0056] Further, the total monomer mass of the hydrophobic monomer, acrylamide monomer and cationic monomer in step S2 accounts for 15-45% of the mass of B liquid, the molar mass of the cationic monomer accounts for 10-50% of the total monomer, and the molar mass ratio of the acrylamide monomer to the hydrophobic monomer is (7.75-6.25):(0.25-1.75).

[0057] As an embodiment of the present application, the molar mass ratio of the acrylamide monomer, cationic monomer and hydrophobic monomer is 7.75:2:0.25, 7.5:2:0.5, 7.25:2:0.75, 7:2:1, 6.75:2:1.25, 6.5:2:1.5, 6.25:2:1.75. Under a preferred condition, the molar mass ratio of the acrylamide monomer, cationic monomer and hydrophobic monomer is 7.5:2:0.5, 7.25:2:0.75, 7:2:1. Under a more preferred condition, the molar mass ratio of the acrylamide monomer, cationic monomer and hydrophobic monomer is 7.25:2:0.75, 7:2:1.

[0058] Further, the amount of the surfactant in step S1 accounts for 1.3-5.3% of the total monomer mass fraction, the amount of the solubilizer in step S2 accounts for 0.1-0.7% of the total monomer mass fraction, and the amount of the photoinitiator in step S3 accounts for 0.01-0.07% of the total monomer mass fraction.

[0059] Further, the low-pressure ultraviolet lamp in step S4 is 24W or 48W, the radiation wavelength is 253.7nm, and the light irradiation reaction time is 2-8h.

[0060] As an embodiment of the present application, the light irradiation reaction time in step S4 is 2h, 4h, 6h, 8h. Under a preferred condition, the light irradiation reaction time is 4h, 6h. Under a more preferred condition, the light irradiation reaction time is 4h.

[0061] In order to better understand the present application, the present application is further specifically described by the following examples, but it should not be understood as a limitation of the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above application content are also regarded as falling within the protection scope of the present application.

[0062] Example 1

[0063] First, 0.645 mL of hydrophobic monomer (perfluorohexylethyl methacrylate), 0.1 g of surfactant CTAB (cetyltrimethylammonium bromide), and 5.905 mL of deionized water were added to a quartz synthesis bottle and stirred at a speed of 500 r / min for 1 h with a magnetic stirrer to make the solution transparent as solution A, at which time the solution pH was adjusted to 4.0 using a dilute hydrochloric acid solution and a sodium hydroxide solution. Then, 1.089 g of acrylamide monomer, 1.835 mL of cationic monomer (methacrylamidopropyl trimethylammonium chloride), and 0.009 g of solubilizer (urea) were added to the A solution, and the whole was protected by nitrogen gas, the reaction temperature was adjusted to 25°C in a water bath, and it was fully mixed by stirring at a speed of 500 r / min for 1 h with a magnetic stirrer to obtain B solution; 0.0009 g of a photoinitiator was added to the B solution, stirred for 10 min, and the quartz synthesis bottle containing the mixed liquid was placed in a UV photocatalyst for photoreaction for 4 h, after which it was solidified at room temperature for 4 h to obtain a gel-like substance C.

[0064] After the solidification was completed, the gel-like substance C was transferred to a mixture of ethanol and acetone, and was cut into pieces with scissors for full washing, after which it was dried in an electric heating air drying oven at 60°C for 24 h to obtain a solid product, which was ground into powder, i.e., the hydrophobic flocculant.

[0065] The hydrophobic flocculant P(AM-MAPTAC-TEMAc6) obtained in this example has a polyacrylamide backbone, and the adsorption structural unit and the hydrophobic structural unit are embedded in the polyacrylamide molecular chain, wherein the total monomer mass accounts for 30% of the total solution mass, the molar mass fraction ratio of acrylamide monomer, cationic monomer, and hydrophobic monomer is 7:2:1, and the hydrophobicity of the copolymerized hydrophobic flocculant is 10%, and the intrinsic viscosity is 540 mL / g. The scanning electron microscope image of the obtained hydrophobic flocculant P(AM-MAPTAC-TEMAc6) is shown in FIG. 1. Figure 7

[0066] Example 2

[0067] ​First, add 0.604 mL of hydrophobic monomer (perfluorohexyl ethyl methacrylate), 0.1 g of surfactant CTAB (hexadecyltrimethylammonium bromide), and 5.164 mL of deionized water to a quartz synthesis flask, and stir with a magnetic stirrer at 500 r / min for 1 h until the solution becomes clear. This is solution A. At this time, adjust the pH of the solution to 4.0 using dilute hydrochloric acid solution and sodium hydroxide solution. Then, 1.408 g of acrylamide monomer, 2.291 mL of cationic monomer (methacrylamidopropyltrimethylammonium chloride) and 0.0105 g of solubilizer (urea) were added to solution A. Nitrogen gas was introduced throughout the process for protection. The reaction temperature was adjusted to 25 °C in a water bath. The mixture was stirred at 500 r / min for 1 h with a magnetic stirrer to ensure thorough mixing, resulting in solution B. 0.0012 g of photoinitiator was added to solution B and stirred for 10 min. The quartz synthesis bottle containing the mixed liquid was placed in a UV photocatalyst and irradiated for 4 h. After irradiation, the mixture was cured at room temperature for 4 h to obtain gel C.

[0068] After curing, the gel C is transferred to a mixture of ethanol and acetone and cut into small pieces with scissors to wash it thoroughly. After washing, it is dried in an electric heating oven at 60°C for 24 hours to obtain a solid product. The solid is then ground into powder, which is the hydrophobic flocculant.

[0069] The hydrophobic flocculant obtained in this embodiment has polyacrylamide as the main chain, with adsorption and hydrophobic structural units embedded in the polyacrylamide molecular chain. The total monomer mass accounts for 35% of the total solution mass, and the molar mass ratio of acrylamide monomer, cationic monomer, and hydrophobic monomer is 7.25:2:0.75. The hydrophobicity of the copolymerized hydrophobic flocculant is 7.5%, and the intrinsic viscosity is 727 mL / g. The obtained hydrophobic flocculant P(AM-MAPTAC-TEMAc6) has… 1 HNMR spectrum as follows Figure 8 As shown, the formation of the polymer can be understood.

[0070] To further demonstrate the beneficial effects of the present invention and to better understand it, the technical features and / or advantages of the hydrophobic flocculant and its preparation method disclosed in the present invention are further illustrated by the following comparative examples and embodiments, but these should not be construed as limiting the present invention. Any adjustments to parameters or processes made by those skilled in the art based on the above-described properties, or applications made based on the above-described properties, are also considered to fall within the protection scope of the present invention.

[0071] Example 1: Selection of Hydrophobic Structural Units

[0072] Hydrophobic structural units were polymerized using acrylate (BA), styrene (STY), laurate acrylate (LA), trifluoroethyl methacrylate (TFEMA), and perfluorohexyl ethyl methacrylate (TEMAc6) as monomers, respectively. Taking P-BA as an example, where P- signifies the polymerized structural unit, and the subscript 1 in P-BA1 indicates one hydrophobic structural unit, P-BA... 10 The subscript 10 indicates 10 hydrophobic structural units.

[0073] To investigate the hydrophobic properties of hydrophobic structural units, this invention employs molecular dynamics (MD) simulations. The radial water density distribution of the hydrophobic branches within the structural units is calculated to analyze their impact on the surrounding water structure. The results are as follows: Figure 2 As shown. The radial radius is in Within the range, the water density around the hydrophobic structural unit follows the order: P-BA1 > P-STY1 > P-LA1 > P-TFEMA1 > P-TEMAc61, with relatively small differences in water density. It is known that the branches of P-BA1 and P-LA1 are hydrocarbon chains with carbon chain lengths of 4 and 12, respectively; the branches of P-TFEMA1 and P-TEMAc61 are mainly fluorocarbon chains with carbon chain lengths of 2 and 8, respectively. It can be observed that the water density difference between P-TEMAc61 and P-TFEMA1 is greater than that between P-LA1 and P-BA1, and the water densities of P-TEMAc61 and P-TFEMA1 are less than those of P-LA1 and P-BA1, respectively. This indicates that the fluorocarbon structure has a significant impact on water density. (Radial radius greater than...) Subsequently, the ring-like structure of P-STY1 enables it to... The water density is lowest at the front; the density of P-LA1 is lower than that of P-TFEMA1, and the effect of carbon chain length on water density begins to be significant. Radial radius is... Within the range, the distance between the head of the fluorocarbon branch and -CH3 is Both P-TEMAc61 and P-TFEMA1 have one more -CH3 group in their main chains than P-LA1 and P-BA1, indicating that the adsorption of water molecules by -CH3 leads to an increase in the water density of P-TEMAc61 and P-TFEMA1, with an influence range of approximately [missing information]. Radial radius greater than Afterwards, the water density around the hydrophobic structural units is in the order of P-STY1 > P-BA1 ≈ P-TFEMA1 > P-LA1 > P-TEMAc61. It can be seen that the water density around P-LA1 and P-TEMAc61 is smaller than that around P-BA1 and P-TFEMA1, respectively, which indicates that the longer the carbon chain is, the greater the influence on the water density. The difference in water density between P-TEMAc61 and P-TFEMA1 is greater than that between P-LA1 and P-BA1, and the water density of P-TEMAc61 is significantly smaller than that of P-LA1. It is not difficult to judge that the more fluorocarbon structures have a more significant impact on the surrounding water. In addition, P-STY1 has a benzene ring, and the distance between the para-hydrogen on the benzene ring is , the atomic distance on the benzene ring in the radial range, so the water density is smaller. In summary, the order of hydrophobic performance is P-TEMAc61 > P-LA1 > P-TFEMA1 ≈ P-BA1 > P-STY1.

[0074] Further, the radius of gyration (R g ) is the distance between the atom in the molecular chain and the center of mass, which is an index for measuring the mass radius in MD simulation, and is defined as:

[0075]

[0076] wherein R g is the radius of gyration m i is the mass (g) of atom i; r i is the distance between atom i and the center of mass The root mean square radius (MSR) is calculated according to R g and the distribution probability , which can directly reflect the conformation and size parameters of the hydrophobic structural unit, and is an important parameter for analyzing the degree of intermolecular association, and is defined as:

[0077]

[0078] Considering that the hydrophobic structural unit exists in isolation in an aqueous solution, there is no intermolecular interaction, and the conformation is stretched or contracted to eventually reach a dynamic equilibrium. When the concentration of the hydrophobic structural unit increases, due to the presence of hydrophobic branches, intermolecular association occurs, and the relative concentration of the hydrophobic region makes the molecule mainly contract, and the stronger the association performance, the deeper the curling degree of the hydrophobic structural unit. Table 1 is the MSR of the hydrophobic structural unit. As can be seen from Table 1, the MSRs of P-TFEMA and P-STY with the shortest chain length are equal before and after the concentration change. Due to the weak hydrophobic performance and short chain length of P-TFEMA1 and P-STY1, P-TFEMA 10 and P-STY 10It forms aggregates more slowly and has weaker association properties. P-BA1 and P-TFEMA1 have comparable hydrophobic properties, while P-BA... 10 A slight decrease in MSR indicates that P-BA 10 Its associative properties are stronger than those of P-TFEMA 10 This is mainly because P-BA1 has a longer carbon chain. P-LA 10 and P-TEMAc6 10 Compared to P-LA1 and P-TEMAc61, they are respectively curled and P-LA 10 and P-TEMAc6 10 The associative properties are comparable, which further indicates that the associative properties increase with increasing chain length or enhanced hydrophobicity. Figure 3 For hydrophobic structural unit R g of It can be seen that, compared with the isolated hydrophobic structural units, the increased concentration of P-TFEMA... 10 and P-STY 10 R g The distribution remains basically unchanged; P-BA 10 In R g for Increased probability distribution; P-TEMAc6 10 Mainly focused on R g for Place; while P-LA 10 R g exist The distribution is relatively uniform. In summary, the association strength of the hydrophobic structural units is P-TEMAc6. 10 >P-LA 10 P-BA 10 >P-TFEMA 10 ≈P-STY 10 Since larger molecules have stronger steric hindrance effects and are more difficult to copolymerize, P-TEMAc6 was selected as a novel hydrophobic active hydrophobic structure for flocculants based on hydrophobic property analysis.

[0079] Table 1. MSR of hydrophobic structural units

[0080]

[0081] Comparative Example 1: Analysis of the adsorption performance and turbidity removal efficiency of commercially available polyacrylamide flocculants, monocationic flocculants, and the flocculant of the present invention.

[0082] N682, A6056 and C6360 are representative of commercially available polyacrylamide flocculants (Table 2), in which C6360 is a cationic polyacrylamide and the cationic monomer used to synthesize it is acryloyloxyethyl trimethyl ammonium chloride (DAC).

[0083] Table 2 Structure of commercially available polyacrylamide flocculants

[0084]

[0085] The different active functional groups on the flocculants result in different adsorption performance on the mineral particles, which is macroscopically manifested as different adsorption capacity. Figure 4 (a) and (b) are the adsorption capacity of commercially available polyacrylamide flocculants on the surface of micro-fine kaolinite particles. The results are shown in Figures 1 and 2. Figure 4 It can be seen that N682 and A6056 have the same adsorption trend on the kaolinite particles. When the dosage of N682 is less than 0.06 mg / g or the dosage of A6056 is less than 0.03 mg / g, it is in the rapid adsorption stage on the kaolinite particles; when the dosage of N682 is greater than 0.06 mg / g or the dosage of A6056 is greater than 0.03 mg / g, the adsorption capacity increases slowly. When the dosage of N682 or A6056 is low, the relative adsorption sites on the surface of the kaolinite particles are sufficient, and the adsorption capacity increases rapidly. When the dosage increases, the adsorption sites are relatively insufficient, and N682 or A6056 will slow down the increase of the adsorption capacity through intermolecular interaction. Under the same dosage, the adsorption capacity of N682 is higher than that of A6056, indicating that the adsorption performance of N682 on the surface of kaolinite is stronger than that of A6056. In addition, although the adsorption capacity increases with the increase of the dosage of N682 or A6056, more residual molecular chains of N682 or A6056 have a significant impact on the adsorption effect. When the dosage of C6360 is less than 0.36 mg / g, the adsorption capacity basically shows a linear increasing trend, and C6360 occupies more molecular chains on the same adsorption sites of kaolinite, which means that C6360 has the strongest adsorption capacity. When the dosage reaches 0.48 mg / g, a large amount of C6360 diffuses in water, and the electrostatic repulsion between the residual molecular chains affects the molecules that have been adsorbed on the surface of kaolinite, resulting in a decrease in the adsorption capacity.

[0086] As Figure 4(d) As shown, the turbidity of the supernatant decreased rapidly when the dosage of N682 was less than 0.06 mg / g; the turbidity decreased slowly when the dosage was in the range of 0.06-0.12 mg / g; the dosage increased and the adsorption capacity of kaolinite particles increased, which could capture more fine particles in the suspension, so the turbidity decreased; when the dosage was greater than 0.12 mg / g, the residual N682 hindered the flocculation and sedimentation of particles, and the turbidity began to increase. The relative turbidity decreased rapidly when the dosage of A6056 was less than 0.03 mg / g; the turbidity decreased slowly when the dosage was in the range of 0.03-0.12 mg / g; similarly, when the dosage was greater than 0.12 mg / g, the turbidity began to increase. It can be found that the adsorption capacity of A6056 is weaker than that of N682 before 0.03 mg / g, and the residual amount is greater than that of N682. The bridging effect between the flocculant with more residual amount and particles is more conducive to capturing fine mineral particles, and the turbidity of A6056 is lower than that of N682. This phenomenon can also be observed in the treatment of kaolinite suspension by C6360. C6360 has the strongest adsorption capacity, and the turbidity is as high as 1256.67 NTU when the dosage is 0.015 mg / g. The adsorption on the surface of kaolinite particles changes less and it is difficult to form a bridging mechanism, resulting in a higher turbidity. In the range of 0.03-0.36 mg / g, the particles adsorbed with C6360 aggregate and settle, and the turbidity continuously decreases. When it reaches 0.48 mg / g, the residual molecular chain leads to a decrease in adsorption capacity, and the turbidity increases.

[0087] A monocationic flocculant P(AM-MAPTAC) was prepared using methacrylamidopropyl trimethylammonium chloride as a cationic monomer. Among them, P(AM-MAPTAC)-20 and P(AM-MAPTAC)-30 represent the cationic degree of 20% and 30%, respectively.

[0088] Figure 5(a) shows the adsorption amount of P(AM-MAPTAC) on fine kaolinite particles. It can be seen that before the dosage is 0.36 mg / g, the adsorption amount increases linearly; after exceeding 0.36 mg / g, the increase in adsorption amount decreases compared to the dosage, and the residual amount of P(AM-MAPTAC)-30 in the aqueous solution is greater than that of P(AM-MAPTAC)-20. This means that before 0.36 mg / g, the adsorption sites on the surface of kaolinite particles are sufficient to accommodate more P(AM-MAPTAC) molecules. With increasing dosage, P(AM-MAPTAC) can continuously adsorb onto the kaolinite surface, and its adsorption effect on the kaolinite particles continuously strengthens. When the concentration exceeds 0.36 mg / g, P(AM-MAPTAC)-30 reaches saturation adsorption on the kaolinite surface, even affecting molecules already adsorbed on the surface and causing a decrease in adsorption capacity. Meanwhile, the adsorption capacity of P(AM-MAPTAC)-20 on kaolinite particles continues to increase, mainly due to electrostatic repulsion between molecules. P(AM-MAPTAC)-30 has a higher cationicity than P(AM-MAPTAC)-20, and the greater the electrostatic repulsion, the easier it is for P(AM-MAPTAC) to remain in the aqueous solution.

[0089] The foregoing has already shown that the adsorption capacity of the three commercially available polyacrylamide flocculants on kaolinite particles is in the order of C6360 > N682 > A6056. It is not difficult to observe that, similarly, the increase in adsorption capacity of P(AM-MAPTAC) decreases after reaching a concentration greater than 0.36 mg / g, but the decrease is less than that of C6360. This indicates that P(AM-MAPTAC)-30 has a stronger adsorption capacity on kaolinite particles than C6360.

[0090] Figure 5 (b) represents the turbidity of the supernatant after the kaolinite suspension has settled. For example... Figure 5 As shown, before the dosage of the reagent was 0.12 mg / g, the turbidity of the supernatant of P(AM-MAPTAC)-30 was less than that of P(AM-MAPTAC)-20. This is mainly because P(AM-MAPTAC)-30 has a high charge density, and the double electric layer thickness of the kaolinite particles that adsorb P(AM-MAPTAC)-30 is less than that of P(AM-MAPTAC)-20. The electrostatic repulsion between the particles is small, making them more likely to aggregate and settle. After the dosage was 0.12 mg / g, the turbidity was less than 30 NTU, indicating that P(AM-MAPTAC) can effectively remove fine kaolinite particles.

[0091] The hydrophobic flocculant prepared in Examples 1-2 is P(AM-MAPTAC-TEMAc6). Figure 6(a) and (b) represent the adsorption amount of P(AM-MAPTAC-TEMAc6) on kaolinite particles and the turbidity of the supernatant after sedimentation, respectively. P(AM-MAPTAC-TEMAc6)-7.5 and P(AM-MAPTAC-TEMAc6)-10 represent hydrophobic flocculants with hydrophobicity of 7.5% and 10%, respectively.

[0092] As can be seen, the adsorption capacity increases linearly with the increase of P(AM-MAPTAC-TEMAc6) dosage, indicating that the adsorption capacity of P(AM-MAPTAC-TEMAc6) on the kaolinite surface is continuously enhanced. This suggests that when the P(AM-MAPTAC) dosage is greater than 0.36 mg / g, the adsorption capacity decreases due to the electrostatic repulsion between molecular chains. After introducing the hydrophobic monomer, the adsorption capacity of P(AM-MAPTAC-TEMAc6) did not decrease significantly. The fluorocarbon chains cause molecular chain association, forming a network structure that more easily captures solid particles in the colloidal suspension, resulting in lower supernatant turbidity. When the dosage is less than 0.03 mg / g, P(AM-MAPTAC)-20 has a low charge density, making aggregation and sedimentation difficult. P(AM-MAPTAC-TEMAc6)-7.5 and P(AM-MAPTAC-TEMAc6)-10 adsorb onto kaolinite particles, and their hydrophobic structural units enhance the bridging mechanism of the hydrophobic flocculant through association, significantly reducing the turbidity of the supernatant and demonstrating excellent turbidity removal efficiency. At dosages greater than 0.03 mg / g, P(AM-MAPTAC-TEMAc6) produces less turbidity than commercially available polyacrylamide flocculants and P(AM-MAPTAC), further indicating that it has the highest turbidity removal efficiency. The structures of both P-MAPTAC and P-TEMAc6 are conducive to the sedimentation of suspended particles.

[0093] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydrophobic flocculant comprising adsorbing structural units and hydrophobic structural units mosaic in polyacrylamide molecular chains, characterized in that, The cationic monomer constituting the adsorption structure unit is methyl methacrylamide propyl trimethyl ammonium chloride, and the hydrophobic monomer constituting the hydrophobic structure unit is perfluorohexyl ethyl methacrylate; The reaction equation of the hydrophobic flocculant is: ； The copolymer cationic degree of the hydrophobic flocculant is 10-50%, and the hydrophobic degree is 2.5-17.5%. The preparation method of the hydrophobic flocculant comprises the following specific steps: S1, a certain amount of hydrophobic monomer, surfactant and deionized water are mixed, and the pH of the reaction system is adjusted to 2.5-5.5, and a transparent solution is obtained after sufficient dispersion, which is used as A liquid; S2, a certain amount of acrylamide monomer, cationic monomer and solubilizer are added to the A liquid, nitrogen is introduced throughout the process, and the mixture is mixed at room temperature to obtain B liquid; S3, a certain amount of photoinitiator is added to the B liquid, and the mixture is mixed thoroughly, and then the mixture is transferred to a light irradiation reaction device; S4, after being irradiated by a low-pressure ultraviolet lamp for a certain time, the mixture is solidified at room temperature for 2-4 h to obtain a gel C; S5, the gel C is transferred to a mixture of ethanol and acetone, and is cut into small pieces for washing to obtain a solid D; S6, the solid D is dried for 24 h, and is ground to obtain a finished product flocculant; In the step S2, the total monomer mass of the hydrophobic monomer, acrylamide monomer and cationic monomer accounts for 15-45% of the mass of the B liquid, the molar mass of the cationic monomer accounts for 10-50% of the total monomer, and the molar mass ratio of the acrylamide monomer to the hydrophobic monomer is (7.75-6.25):(0.25-1.75).

2. The method for producing a hydrophobic flocculant according to claim 1, wherein The acrylamide is used as a main chain monomer, the methyl methacrylamide propyl trimethyl ammonium chloride is used as a cationic monomer, and the perfluorohexyl ethyl methacrylate is used as a hydrophobic monomer, and a copolymer is polymerized by low-pressure ultraviolet initiation.

3. The hydrophobic flocculant according to claim 1, characterized by, The surfactant in the step S1 is cetyl trimethyl ammonium bromide, the solubilizer in the step S2 is urea, and the photoinitiator in the step S3 is one of azobisdiisobutyl amide hydrochloride, azobisdiisopropyl imidazole hydrochloride, azobis dicyanopentanoic acid, azobis imidazoline base propane and irgacure 2959.

4. The hydrophobic flocculant of claim 1, wherein The amount of the surfactant in the step S1 accounts for 1.3-5.3% of the total monomer mass fraction, the amount of the solubilizer in the step S2 accounts for 0.1-0.7% of the total monomer mass fraction, and the amount of the photoinitiator in the step S3 accounts for 0.01-0.07% of the total monomer mass fraction.

5. The hydrophobic flocculant of claim 1, wherein The low-pressure ultraviolet lamp in the step S4 is 24W or 48W, the radiation wavelength is 253.7 nm, and the light irradiation reaction time is 2-8 h.

6. The hydrophobic flocculant according to claim 1 is applied in wastewater treatment.

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