Self-assembled imitate sea anemone nanoflocculant and preparation method thereof

Abstract

The present application belongs to the technical field of water treatment, and particularly relates to a self-assembled sea anemone-like nanoflocculant and a preparation method thereof. The present application first prepares an aliphatic-quaternary ammonium / imidazole-silicon aluminum complex, utilizes the characteristics of long alkyl chain hydrophobicity and double cation hydrophilicity, forms a "core-shell" structure micelle through self-assembly, and then forms an intelligent sea anemone-like nanoflocculant solid through freeze-drying. The self-assembled sea anemone-like nanoflocculant removes the suspended solids and colloids through the "core-shell" structure, wherein the "shell" part is an inorganic flocculant, the "core" part is an organic flocculant, and the "shell" part is dissolved to remove the suspended solids and colloids and drive the outward turning of the organic functional groups of the "core" part, like the tentacles of sea anemones capturing water-soluble organic matters.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a self-assembling sea anemone-like nano-flocculant and a preparation method thereof. Background Art

[0002] With the rapid development of the rural economy, rural water pollution is attracting increasing attention. According to statistics, 16 billion tons of rural domestic sewage is generated annually nationwide, of which only 19.4% of township domestic sewage receives institutional treatment. In addition to rural domestic sewage, irrational livestock wastewater management, excessive use of agricultural fertilizers and pesticides, and wastewater discharge from township enterprises all contribute to rural water pollution. Rural sewage is large in volume, complex in composition, and difficult to treat in depth, making it difficult for conventional water treatment technologies to meet surface water discharge standards. Flocculants are a key treatment agent in in-situ water treatment processes and typically include inorganic (inorganic salts and polysalts of iron and aluminum) and organic flocculants. Inorganic flocculants are commonly used in large-scale sewage treatment due to their low cost, but they present challenges such as high feed requirements, large sedimentation volumes, and susceptibility to pipe corrosion. Compared to inorganic flocculants, organic flocculants require lower dosages, produce smaller sludge volumes, and do not consume alkalinity during the flocculation process.

[0003] Since there are a large number of negatively charged organic matter in rural sewage, when cationic flocculants are used alone, they can play the dual role of electrical neutralization and bridging. However, the capture rate of organic matter by organic flocculants is usually lower than that of inorganic flocculants. This is because the hydroxide gel formed by inorganic flocculants has an adsorption effect on water-soluble organic matter. Inorganic flocculants can remove more than 20% of water-soluble organic matter, especially soluble components with large molecular weight (>10kDa) and strong hydrophobicity (such as humic acid). Enhancing the capture rate of water-soluble organic matter by organic flocculants is a key problem in improving their water treatment capacity. Due to the different mechanisms of action of inorganic and organic flocculants, it is usually difficult to use them in a compound form for sewage treatment. Therefore, the use of chemical modification methods to develop water treatment reagents that have the advantages of both inorganic and organic flocculants will provide a new way for deep treatment of rural sewage. Summary of the Invention

[0004] The purpose of the present invention is to provide a self-assembled sea anemone-like nano-flocculant, which can form a "core-shell" structure, thereby achieving the purpose of efficient flocculation and sedimentation pretreatment of sewage.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A method for preparing a self-assembled sea anemone-like nano-flocculant, the method comprising the following steps:

[0007] S1. Preparation of aliphatic-quaternary ammonium / imidazole-silicon-aluminum complex:

[0008] Preparation of aliphatic-quaternary ammonium / imidazole-silicon aluminum complex of general formula When R is N, the structure is

[0009]

[0010] When R is imidazole group, the structure is

[0011]

[0012] n in the alkyl chain C n H 2n+1 is 12-18; the anion is sulfate or chloride, preferably sulfate;

[0013] S2, the above intermediate is dissolved in methanol aqueous solution, the system pH is adjusted to 1-3 with dilute sulfuric acid, and the condensation reflux is carried out at 60-90 DEG C for 0.5-3h, after the reaction is completed, the remaining solvent is removed by rotary evaporation after natural cooling, and the hydrolysis product is obtained;

[0014] The volume ratio of methanol and water in the methanol aqueous solution is 6-10:1,

[0015] S3, the obtained hydrolysis product is dispersed into water, the system pH is adjusted to 1-3 with dilute sulfuric acid, Al2(SO4)3 aqueous solution is added to make the molar ratio of [Si]:[Al] 1:5-20, NaOH aqueous solution is added to make the molar ratio of [Al]:[OH] 1:0.5-2, finally dilute sulfuric acid is used to adjust the pH to 2-4, and the self-assembly reaction is carried out after stirring and aging at room temperature for 6-24h, and finally freeze-drying is carried out to obtain the solid flocculant.

[0016] The self-assembly anemone-like nano flocculant removes the flocculation and precipitation through the "core-shell" structure, and the structure diagram of the anemone-like nano flocculant is as shown in Figure 1 The "shell" part is an inorganic flocculant, the "core" part is an organic flocculant, the "shell" part is dissolved to remove the suspended matter and colloid, and the "core" part organic functional group is turned outwards, like the tentacles of anemone capturing water-soluble organic matter in water. The design alleviates the combination problem of inorganic and organic flocculants, and the flocculant is used for complex flocculation treatment of ammonia nitrogen in sewage, and has excellent flocculation performance in a short time.

[0017] As preferred, the preparation of the intermediate of the quaternary ammonium salt anemone-like nano flocculant:

[0018] KI was added to a flask, and nitrogen was introduced to remove oxygen in the device. N,N-dimethylhexadecylamine and (3-aminopropyl)trimethoxysilane were added under magnetic stirring. Methanol was used as a solvent, and the mixture was refluxed at 50-70°C for 12-28 hours. After the reaction was completed, the mixture was naturally cooled, and the excess solvent was removed by rotary evaporation. 3-(trimethoxysilyl)propyl-n-hexadecyldimethylammonium iodide was obtained by recrystallization.

[0019] The mass volume ratio of KI to (3-aminopropyl)trimethoxysilane is 0.1g~2ml-4ml;

[0020] The volume ratio of the N,N-dimethylhexadecylamine and (3-aminopropyl)trimethoxysilane is 1 to 3:1, and the optimal ratio is 2:1.

[0021] Preferably, the temperature of the methanol condensation reflux is 70° C. and the time is 24 hours; and the recrystallization solvent is an acetone-methanol mixture with a volume ratio of 1:1.

[0022] As a preferred method, the preparation of imidazole salt anemone-like nano-flocculant intermediate is as follows:

[0023] n-Dodecyl imidazole and (3-chloropropyl)trimethoxysilane were added to a flask with toluene as the solvent. The flask was sealed and nitrogen was introduced. The reaction mixture was heated under reflux at 80-110° C. for 24-72 hours under magnetic stirring. After the reaction was completed, the mixture was naturally cooled and the excess solvent was removed by rotary evaporation. The resulting viscous liquid was washed with diethyl ether and dried in vacuo to obtain 1-dodecyl-3-[3-(trimethoxysilyl)propyl]-1-chloroimidazole;

[0024] The molar ratio of n-dodecyl imidazole to (3-chloropropyl) trimethoxysilane is 1 to 2:1, and the optimal ratio is 2:1.

[0025] Preferably, the toluene is heated under reflux at a temperature of 100° C. for 48 hours.

[0026] Preferably, in S2, the volume ratio of methanol to water in the methanol aqueous solution is 9:1;

[0027] In S2, the pH value was adjusted to 2.2 by adding dilute sulfuric acid. In S3, the pH value was adjusted to 2.2 by adding dilute sulfuric acid for the first time and to 3.5 by adding dilute sulfuric acid for the second time.

[0028] Preferably, in S2, the condensation reflux temperature of the methanol aqueous solution is 80°C.

[0029] Preferably, in S3, an Al2(SO4)3 aqueous solution is added to make the [Si]:[Al] molar ratio of 1:10; and a NaOH aqueous solution is added to make the [Al]:[OH] molar ratio of 1:1.

[0030] Preferably, in S3, the stirring and aging time at room temperature is 12 hours; before freeze-drying, it needs to be frozen in the refrigerator for 12-24 hours, preferably 24 hours; the freeze-drying temperature is -55°C to -40°C, preferably -48°C, and the freeze-drying time is 3-6 hours, preferably 4 hours.

[0031] A self-assembled sea anemone-like nanoflocculant obtained by the preparation method of the present invention. Two self-assembled sea anemone-like nanoflocculant materials can be prepared according to the preparation method of the present invention, namely a quaternary ammonium salt sea anemone-like nanoflocculant and an imidazolium salt sea anemone-like nanoflocculant. During the self-assembly process, quaternary amine and imidazolium cations have a significant influence on the formation of the sea anemone-like "core-shell micelle" structure. TEM characterization shows that the quaternary ammonium salt nanoflocculant material exhibits a typical sea anemone-like nanostructure and exhibits higher ammonia nitrogen flocculation performance and relatively higher COD flocculation performance for domestic sewage.

[0032] The present invention also provides the flocculation application of the self-assembled sea anemone-like nano-flocculant described in the above technical solution in sewage treatment.

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] The aliphatic-quaternary ammonium / imidazole-silica-aluminum complex provided by the present invention utilizes the hydrophobic properties of long alkyl chains and the hydrophilic properties of dications to form "core-shell" structure micelles through self-assembly, and then forms an intelligent sea anemone-like nano-flocculant solid through freeze-drying. The intelligent flocculant formed by self-assembly has a "core-shell" structure. The "shell" composed of the aluminum-silicon complex will undergo hydrolysis phase change to remove suspended matter and colloids; the "core" composed of organic functional groups will turn outward and surround and fix on the "shell", like the tentacles of a sea anemone to capture small molecules in the water, inducing the small molecules to form condensation nuclei and then form flocs for removal. This intelligent flocculant has the advantages of both inorganic and organic flocculants, improves its flocculation and adsorption capacity for toxic components and organic pollutants in sewage, and achieves the purpose of efficient flocculation and sedimentation pretreatment of sewage, thereby providing a good foundation for efficient and low-cost in-situ sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of anemone-like nano-flocculant;

[0036] Figure 2 The SEM and corresponding element mapping images of the quaternary ammonium salt sea anemone-like nano-flocculant TONA prepared in Example 1, wherein a is the microscopic morphology of the flocculant TONA, b is the Al element, c is the C element, d is the Si element, and e is the mapping image of the N element;

[0037] Figure 3This is the SEM image of the imidazole salt anemone-like flocculant TOPA prepared in Example 2 and the mapping diagram of the corresponding elements, wherein a and b are microscopic morphology images of the coagulant TOPA, c is the Al element, d is the C element, e is the Si element, and f is the mapping diagram of the N element;

[0038] Figure 4 IR images of the quaternary ammonium salt sea anemone-like nano-flocculant material TONA and the intermediates 3-(trimethoxysilyl)propyl-n-hexadecyldimethylammonium iodide TMPN and 3-(trihydroxysilyl)propyl-n-hexadecyldimethylammonium iodide TOPN prepared in Example 1;

[0039] Figure 5 IR images of the imidazole salt sea anemone-like nano-flocculant material TOPA and the intermediates 1-dodecyl-3-[3-(trimethoxysilyl)propyl]-1-chloroimidazole TMPC and 1-dodecyl-3-[3-(trihydroxysilyl)propyl]-1-chloroimidazole TOPC prepared in Example 2;

[0040] Figure 6 This is the XPS fitting diagram of the sea anemone-like nano-flocculant TONA prepared in Example 1, wherein a) the broad spectrum of the quaternary ammonium salt flocculant TONA, b) N1s, c) Al2p, and d) Si2p;

[0041] Figure 7 This is the XPS fitting diagram of the sea anemone-like nano-flocculant TOPA prepared in Example 2, wherein a) the broad spectrum of the imidazole salt flocculant TOPA, b) N1s, c) Si2p, and d) Al2p;

[0042] Figure 8 TEM images of the sea anemone-like nano-flocculant TONA prepared in Example 1, wherein a is the HR-TEM image of TONA, b is the HAADF-TEM image of TONA, c is the element C, d is the element Si, e is the element N, and f is the element Mapping-TEM mapping image of Al;

[0043] Figure 9 TEM images of the sea anemone-like nano-flocculant TOPA prepared in Example 2, wherein a is the HR-TEM image of TOPA, b is the HAADF-TEM image of TOPA, c is the element Si, d is the element C, e is the element Al, and f is the element mapping-TEM image of N;

[0044] Figure 10 This is a schematic diagram of a surface tension measuring device, wherein: 1, capillary; 2, spherical glass tube; 3, stopcock; 4, beaker; 5, vacuum system; 6, interface; 7, connection box; 8, pressure tester; 9, stopcock; 10, dropping funnel. DETAILED DESCRIPTION

[0045] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0046] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0047] The present invention will now be further described in conjunction with specific examples. The following examples are only intended to explain the present invention but do not limit the present invention. The test samples and test procedures used in the following examples include the following (if the specific experimental conditions are not specified in the examples, they are usually based on conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources).

[0048] Example 1 Preparation of quaternary ammonium salt sea anemone-like nano-flocculant material

[0049] 1. Add 0.25 g of KI to a three-necked flask, introduce nitrogen for 5 minutes to remove oxygen in the apparatus, add 7.99 mL of N,N-dimethylhexadecylamine (TM) and 5.54 mL of (3-aminopropyl)trimethoxysilane (PN) under magnetic stirring, use 20 mL of methanol as the solvent, maintain condensation and reflux at 70°C for 24 hours, and after the reaction is completed, allow to cool naturally. Remove excess solvent by rotary evaporation, and then recrystallize at 0°C in acetone:ethanol volume ratio = 1:1 to obtain 3-(trimethoxysilyl)propyl-n-hexadecyldimethylammonium iodide (TMPN).

[0050] 2. Dissolve 2 g of the above product 3-(trimethoxysilyl)propyl-n-hexadecyldimethylammonium iodide in 190 mL of a mixed solvent of methanol and water (V methanol: V water = 9:1), adjust the pH of the reaction system to about 2.2 with 0.5 mol / L dilute sulfuric acid, condense and reflux at 80 ° C for 1 h, wait for the reaction to be completed and cool naturally, and then remove the remaining solvent by rotary evaporation to obtain 3-(trihydroxysilyl)propyl-n-hexadecyldimethylammonium iodide (TOPN).

[0051] 3. Take 80 mg 3-(trihydroxysilyl)propyl-n-hexadecyldimethylammonium iodide dispersed in 10 mL deionized water, use 1 mol / L dilute hydrochloric acid to adjust the pH of the mixed system to 2.0, take 10 mL 0.1 mol / L Al2(SO4)3 aqueous solution according to the molar ratio of [Si]:[Al] 1:10, and slowly add it to the system under stirring, continue to add 2 mL 1 mol / L NaOH aqueous solution to the system according to the molar ratio of [Al]:[OH] 1:1, finally use 0.5 mol / L dilute sulfuric acid to adjust the pH of the mixed system to 3.5, stir and age at room temperature for 12 h, finally put the sample into the refrigerator and freeze for 12 h, and then freeze-dry at -48°C for 24 h, and the obtained flocculant material is the quaternary ammonium salt sea anemone-like nanoflocculant material (TONA).

[0052] Example 2 Preparation of imidazole salt sea anemone-like nanoflocculant material

[0053] 1. In a dry 100 ml flask, add 2.63 ml n-dodecylimidazole (10 mmol), 1.84 ml (3-chloropropyl)trimethoxysilane (10 mmol) and appropriate amount of toluene as solvent, seal and purge with N2 for 20-25 min. Heat the reaction mixture to reflux at 100°C for 48 h under stirring. After the reaction is completed, cool naturally, remove the excess solvent by rotary evaporation, wash the obtained viscous liquid with diethyl ether and dry under vacuum to obtain 1-dodecyl-3-[3-(trimethoxysilyl)propyl]-1-chloroimidazole (TMPC).

[0054] 2. Dissolve 2 g of the product 1-dodecyl-3-[3-(trimethoxysilyl)propyl]-1-chloroimidazole of step (1) above in 180 mL of a mixed solvent of methanol and 20 mL of water (V 甲醇 :V 水 = 9:1), adjust the pH of the reaction system to about 2.2 with 0.5 mol / L dilute sulfuric acid, condense and reflux at 80°C for 1 h, after the reaction is completed, cool naturally, remove the remaining solvent by rotary evaporation to obtain 1-dodecyl-3-[3-(trihydroxysilyl)propyl]-1-chloroimidazole (TOPC).

[0055] 3. Take 71 mg of the product 1-dodecyl-3-[3-(trihydroxysilyl)propyl]-1-chloroimidazole obtained in step (2) and disperse it in 10 mL of deionized water. Adjust the pH of the mixed system to 2.0 with 0.5 mol / L dilute sulfuric acid. Pipette 10 mL of 0.1 mol / L Al2(SO4)3 aqueous solution at a [Si]:[Al] molar ratio of 1:10 and slowly add it to the system under stirring. Continue to add 2 mL of 1 mol / L NaOH aqueous solution to the system at a [Al]:[OH] molar ratio of 1:1. Finally, adjust the pH of the mixed system to 3.5 with 0.5 mol / L dilute sulfuric acid, stir and age at room temperature for 12 h to obtain a flocculant (TONA).

[0056] The distribution of the TONA material prepared in Example 1 and the TOPA material prepared in Example 2 was tested:

[0057] Scanning electron microscopy (SEM) was used to characterize the two flocculant materials. Figure 2 and Figure 3 shown.

[0058] Infrared absorption spectroscopy (IR) was used to characterize the two flocculant materials. Figure 4 and Figure 5 shown.

[0059] X-ray photoelectron spectroscopy (XPS) was used to characterize the two flocculant materials. Figure 7 shown.

[0060] Transmission electron microscopy (TEM) was used to characterize the two flocculant materials. Figure 8 and Figure 9 shown.

[0061] from Figure 2 It can be seen that the microscopic morphology of the quaternary ammonium salt flocculant TONA mainly presents uniformly dispersed microscopic particles with a diameter of approximately 30-50nm. Mapping tests show that TONA contains a large amount of Al, Si and N elements, especially Al, indicating that Al has successfully entered the TONA skeleton. Figure 3 Unlike the quaternary ammonium salt flocculant TONA, the imidazole salt flocculant TOPA exhibits severe particle agglomeration. A zoomed-in image reveals that the particles are primarily spherical or cylindrical. Mapping tests reveal that TOPA contains relatively low levels of Al, Si, and N.

[0062] In order to confirm the structure of the flocculant material, we first performed FT-IR tests on the freeze-dried flocculant TONA and its precursor, such as Figure 4FT-IR spectra of 3-(trimethoxysilyl)propyl-n-hexadecyldimethylammonium iodide. Peaks at 2853, 2926 cm -1 belong to the stretching vibration of C-H in the nitrogen methyl and methylene; the peak at 2363 cm -1 is due to the stretching vibration of N-H; the peaks at 1132-1043 cm -1 are the asymmetric stretching vibration absorption peaks of Si-O-CH3; the peak at 814 cm -1 is the characteristic absorption peak of Si-C. The above results show that 3-(trimethoxysilyl)propyl-n-hexadecyldimethylammonium chloride (TOPN) is successfully synthesized, and after hydrolysis, a clear O-H absorption peak appears at 3422 cm -1 , and 3-(trimethoxysilyl)propyl-n-hexadecyldimethylammonium iodide has been hydrolyzed. In the FT-IR spectrum of the flocculant (TPNA), the O-H absorption peak is weakened, and a clear Al-O peak appears at 1139 cm -1 , indicating that the product obtained after Si-Al reaction is the target flocculant TONA. In contrast, as Figure 5 indicated, in the FT-IR spectrum of 1-dodecyl-3-[3-(trimethoxysilyl)propyl]-1-chloroimidazole, peaks at 2853, 2926 cm -1 belong to the stretching vibration of C-H in the nitrogen methyl and methylene, the peaks at 3072 cm -1 and 3142 cm -1 can be attributed to the characteristic peaks of imidazole; in the FT-IR spectrum of the flocculant (TOPA), a clear Si-O-C, Al-O peak appears at 1048 cm -1 , 1139 cm -1 . It may be that the particle aggregation in the flocculant is serious or contains residual raw materials, and the morphology of the flocculant is not ideal compared with TONA.

[0063] To further confirm the structure of the flocculant TONA material, we tested its TONA chemical structure and electronic structure by XPS, as shown in Figure 6 . The wide spectrum shows that Al and Si elements account for 10% and 2% of the main five elements of TONA, respectively, indicating that the target flocculant is successfully Si-Al. The N, Si, and Al element peaks are integrated, Figure 6 b shows that the N element has two peaks at 400.1 eV and 402.5 eV, which can be attributed to the peaks of part of tertiary amine nitrogen and quaternary amine nitrogen, indicating that there is indeed quaternary amine nitrogen in the flocculant, which further supports the above infrared results. Figure 6c and 6d show single characteristic peaks of Al-O-Si and Si-O-Al, respectively, which once again proves that the material obtained by Si-Al treatment is the target flocculant. Figure 7 XPS test shows the electronic structure of TOPA flocculant. The broad spectrum shows that Al and Si elements in TOPA account for 16% and 2% respectively. The N, Si, and Al element peaks are integrated respectively. Figure 7 b shows that the only characteristic peak of N element is located at 400.6eV, which can be attributed to the imidazole nitrogen peak, indicating that the imidazole nitrogen peak does exist in the flocculant. Figure 7 c and 7d show single characteristic peaks of Al-O-Si and Si-O-Al, respectively, which again supports the test results of mapping and infrared, proving that the material obtained by Si-Al treatment is TOPA flocculant.

[0064] like Figure 8 As shown in the figure, TEM shows that the quaternary ammonium salt flocculant TONA presents a uniformly dispersed particle morphology with a diameter of approximately 30-50nm, which is consistent with the SEM morphology. The HAADF-TEM test results show the morphology of a single flocculant particle. Its morphology is as shown in the structural diagram, showing a typical double-layer spherical structure, like the morphology of a sea anemone. TEM-Mapping shows that the inner layer C element is concentrated ( Figure 8 c) This is likely due to the flocculant's long carbon chains being primarily concentrated in the interior, while the Si element is primarily concentrated between the inner and outer layers, and the Al element is distributed around the outer layer. Transmission electron microscopy clearly shows that the morphology of the flocculant formed by the Si-Al bond matches the desired anemone-like morphology. Figure 9 The TEM morphology of TOPA flocculants is shown to be spherical or long strips. Figure 9 b) HAADF-TEM revealed that the spheres are bounded by other materials, likely residual raw materials. TEM-mapping analysis revealed that Al is distributed in the inner layer, surrounded by Si and C, significantly different from the flocculant TONA. The same silicon-aluminum synthesis results in completely different morphologies, likely due to the stronger affinity of the imidazolium cation for the Al-O bond, which attracts small organic molecules such as imidazolium or Al, preventing the formation of a double-layered spherical ball.

[0065] Application Example 1

[0066] The surface tension of the quaternary ammonium salt sea anemone-like nano-flocculant prepared in Example 1 was tested. Figure 9 shown.

[0067] Connect the dosing tube and the sample tube by rotating the three-way stopcock. Add pure water through the inlet of the dosing tube, so that the capillary opening is tangent to the liquid level in the sample tube (make sure the capillary is vertical), then close the three-way stopcock. Fill the dropping bottle with tap water, close the funnel stopcock, and then read the differential pressure gauge at zero (the six connections are disconnected at this point). Connect the connections so that the sample tube, dropping bottle, and differential pressure gauge form a closed system. Open the stopcock below the dropping bottle and wait for the differential pressure gauge to display a certain value. Close the stopcock and observe the differential pressure. If the pressure difference does not change and remains constant, the system is airtight. If not, reconnect the piping system. Once the system is airtight, open the stopcock of the dropping bottle and adjust the dripping rate to minimize the number of bubbles escaping, at a rate of approximately 15 bubbles per minute. Once the pressure stabilizes, read the maximum absolute value on the differential pressure gauge. Take three consecutive readings and average them. After the measurement, stop dripping, disconnect the connection port, and open the three-way stopcock of the sample tube to release the water.

[0068] Take 5mL, 12.5mL, and 15mL of quaternary ammonium salt flocculant respectively and inject them into three 25mL volumetric flasks, dilute them with water to 20%, 50%, and 60%, and then take 25mL of flocculant. Rinse the sample tube with the test solution and fix it on the iron stand. Use the above determination method to measure the maximum pressure difference (ΔP) of different flocculant concentrations. max ).

[0069] The surface tension of the quaternary ammonium salt sea anemone-like nano-flocculant material prepared in Example 1 was tested using the maximum bubble method. The structure of the surface tension measuring device is as follows: Figure 10 As shown, the device includes: a capillary 1, a spherical glass tube 2, a stopcock 3, a beaker 4, a vacuum system 5, an interface 6, a connection box 7, a pressure tester 8, a stopcock 9 and a dropping funnel 10.

[0070] Application Example 2

[0071] The surface tension of the imidazole salt sea anemone-like nano-flocculant prepared in Example 2 was tested.

[0072] The above steps are the same as those in Application Example 1.

[0073] Inject 0.5mL, 1.25mL, 15mL, and 20mL of quaternary ammonium salt flocculant into three 25mL volumetric flasks, dilute with water to 2%, 5%, 60%, and 80%, and then add 25mL of flocculant. Rinse the sample tube with the test solution and secure it to an iron stand. Measure the maximum pressure difference (ΔPmax) at different flocculant concentrations using the above method.

[0074] The surface tension of the imidazole salt sea anemone-like nano-flocculant material prepared in Example 2 was tested using the maximum bubble method. Figure 10 shown.

[0075] The detection method is the maximum bubble method for measuring surface tension. The test results of surface tension are shown in Tables 1 and 2.

[0076] Table 1 Measurement of surface tension of the quaternary ammonium salt flocculant TONA prepared in Example 1

[0077]

[0078] Table 2 Measurement of surface tension of the imidazole salt flocculant TOPA prepared in Example 2

[0079]

[0080] According to the results in Tables 1 and 2, the surface tension of the quaternary ammonium salt flocculant TONA is obviously smaller than that of the imidazole salt TOPA, which is beneficial to the better flocculation performance of the quaternary ammonium salt flocculant TONA on organic suspended matters or other substances in sewage.

[0081] Application Example 3

[0082] The present application also provides the pretreatment and determination of ammonia nitrogen in a water sample by using the nanometer flocculant.

[0083] Preparation of a standard curve: 0.00, 0.50, 1.00, 2.00, 4.00, 6.00, 8.00 and 10.00 mL of ammonia nitrogen standard solution are respectively added into 8 50 mL colorimetric tubes, and deionized water is added to the mark line to obtain solutions with ammonia nitrogen contents of 0.0, 0.1, 0.2, 0.4, 0.8, 1.2, 1.6 and 2.0 μg / mL. 1.0 mL of potassium sodium tartrate solution is added into each of the 8 colorimetric tubes, and after shaking, 1.0 mL of Nessler's reagent is added and shaken. After 10 min, the absorbance is measured under light with a wavelength of 420 nm with deionized water as a reference, and a standard curve is recorded and drawn.

[0084] Pretreatment: an appropriate amount of sodium thiosulfate solution is added into a water sample (domestic sewage) to remove residual chlorine, and starch potassium iodide test paper is used to test whether the residual chlorine is removed.

[0085] Determination of ammonia nitrogen in a water sample: 50 mL of the pretreated water sample is taken, 1.0 mL of potassium sodium tartrate solution is added, and after shaking, 1.0 mL of Nessler's reagent is added and shaken. After 10 min, the solution is diluted by 10 times, and the absorbance is measured under light with a wavelength of 420 nm with deionized water as a reference. The content of ammonia nitrogen in the water sample is obtained after conversion according to the standard curve.

[0086] (2) Flocculation process

[0087] The prepared flocculant was added to the pretreated water sample at an input amount of 100 mg / L, and the mixture was rapidly stirred at 250 rpm for 1.5 min to uniformly disperse the flocculant, then stirred at 50 rpm for 15 min and allowed to stand for 30 min.

[0088] Draw 50 mL of the flocculated water sample from 2 cm below the surface of the sample after standing. Add 1.0 mL of potassium sodium tartrate solution, shake well, and then add 1.0 mL of Nessler's reagent and shake well. Let the sample stand for 10 minutes. After diluting it 2-fold, measure the absorbance at 420 nm using deionized water as a reference. Calculate the ammonia nitrogen content of the flocculated water sample using the standard curve and conversion.

[0089] The quaternary ammonium salt flocculant TONA and the imidazole salt TOPA of the present invention were used to treat laboratory simulated wastewater and domestic sewage by complexation flocculation, and the treatment effect of the flocculant was investigated by measuring the ammonia nitrogen content in the water.

[0090] The detection method is to measure the ammonia nitrogen concentration before and after sewage treatment using an ultraviolet spectrometer. The measurement results are shown in Tables 3 and 4.

[0091] Table 3 Ammonia nitrogen determination of quaternary ammonium salt flocculant TONA

[0092]

[0093] Table 4 Ammonia nitrogen determination of imidazole salt flocculant TOPA

[0094]

[0095] The results in Tables 3 and 4 show that the quaternary ammonium salt flocculant TONA achieved a flocculation removal efficiency of 84.53% for laboratory simulated wastewater and 84.2% for domestic sewage (real water samples). In contrast, the imidazole salt TOPA achieved a flocculation removal efficiency of only 33.62% for the same laboratory simulated wastewater and 70.43% for domestic sewage (real water samples). This demonstrates that the quaternary ammonium salt nano-flocculant TONA, with its typical sea anemone-like morphology, exhibits extremely high ammonia nitrogen flocculation removal performance.

[0096] Application Example 4

[0097] The invention also provides pretreatment and determination of chemical oxygen demand (COD) of water samples by using nano-flocculants.

[0098] Place 10.0 mL of sample (domestic sewage) in a conical flask. Add an appropriate amount of mercuric sulfate solution, 5.00 mL of potassium dichromate standard solution, and several explosion-proof glass beads, and shake well. Connect the conical flask to the lower end of the condenser of the reflux device. Slowly add 15 mL of silver sulfate-sulfuric acid solution from the upper end of the condenser to prevent the escape of low-boiling organic matter. Continuously shake the conical flask to mix thoroughly, then maintain a gentle reflux for 2 hours.

[0099] After reflux, allow the sample to cool naturally. Rinse the condenser with another 45 mL of deionized water from the top of the condenser and remove the conical flask. Add 3 drops of ferrochlore indicator solution and titrate with ammonium ferrous sulfate standard solution. The titration endpoint is when the solution changes from yellow to blue-green and then to reddish-brown. Record the volume of ammonium ferrous sulfate standard solution consumed and calculate the COD value of the water sample.

[0100] Perform a blank test using the same procedure as the COD determination above, substituting 10.0 mL of deionized water for the water sample. Record the volume of ammonium ferrous sulfate standard solution consumed during the blank titration for blank deduction in calculations.

[0101] The prepared flocculant was added to the pretreated water sample at an input amount of 1 g / L, and the mixture was rapidly stirred at 250 rpm for 1.5 min to uniformly disperse the flocculant, and then stirred at 50 rpm for 15 min and allowed to stand for 30 min.

[0102] Draw 10 mL of flocculated water sample from 2 cm below the liquid surface after standing, dilute it 100 times and transfer 10 mL into a conical flask, and determine the COD value according to the above COD determination steps.

[0103] The self-assembled sea anemone-like nano-flocculant prepared by the present invention was used for complexation flocculation treatment of laboratory simulated wastewater and domestic sewage (real water samples), and the treatment effect of the flocculant was investigated by COD content in the water, as shown in Tables 5 and 6.

[0104] Table 5 COD determination of natural sewage by quaternary ammonium flocculant TONA

[0105]

[0106] Calculation method: Chemical oxygen demand mass concentration ρ (mg / L)

[0107] Wherein C is the molar concentration of ferrous sulfate ammonium, ΔVo is the titration volume of ferrous sulfate ammonium with pure water, ΔV is the titration volume of ferrous sulfate ammonium with sewage, V is the initial volume of pure water or sewage, and f is the dilution factor.

[0108] Calculation results: The sewage at the inlet is 536 mg / L, the sewage after flocculation is 196 mg / L, and the flocculation rate is 63.4%.

[0109] Table 6 COD determination of natural sewage by imidazole salt flocculant TOPA

[0110]

[0111]

[0112] The same calculation results as above: the sewage at the inlet is 536 mg / L, the sewage after flocculation is 204 mg / L, and the flocculation rate is 61.9%.

[0113] According to the results in Tables 5 and 6, the flocculation efficiency of the quaternary ammonium salt flocculant TONA for COD in domestic sewage (real water sample) is 63.4%, while the flocculation removal efficiency of the imidazole salt TOPA for the same domestic sewage (real water sample) is 61.9%.

[0114] In general, compared with imidazolium salt nanoflocculants, quaternary ammonium salt nanoflocculants exhibit a typical sea anemone-like nanostructure and show higher ammonia nitrogen flocculation performance and relatively higher COD flocculation performance for domestic sewage. Therefore, quaternary ammonium salt nanoflocculants can be used as an efficient and green domestic sewage flocculant.

[0115] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0116] The self-assembled sea anemone-like nano-flocculant provided by the present invention and its preparation method are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a self-assembled sea anemone-like nano-flocculant, characterized in that The method comprises the following steps: S1. Preparation of aliphatic-quaternary ammonium / imidazole-silicon-aluminum complex: The general formula for preparation is Aliphatic-quaternary ammonium / imidazole-silicon-aluminum complex, where R is N, has the structural formula ， When R is an imidazole group, the structural formula is ， Alkyl chain C n H 2n+1 n in is 12 to 18; the anion is sulfate or chloride; S2. Dissolve the above-mentioned aliphatic-quaternary ammonium / imidazole-silicon-aluminum complex in a methanol aqueous solution, adjust the system pH to 1-3 with dilute sulfuric acid, reflux at 60-90° C. for 0.5-3 h, cool naturally after the reaction is completed, and remove the remaining solvent by rotary evaporation to obtain a hydrolyzed product; The volume ratio of methanol to water in the methanol aqueous solution is 6 to 10:

1. S3. Disperse the obtained hydrolyzate in water, adjust the pH value of the system to 1-3 with dilute sulfuric acid, add Al2(SO4)3 aqueous solution to make the [Si]:[Al] molar ratio to 1:5-20, then add NaOH aqueous solution to make the [Al]:[OH] molar ratio to 1:0.5-2, and finally adjust the pH value to 2-4 with dilute sulfuric acid, stir and age at room temperature for 6-24 hours to carry out self-assembly reaction, and finally freeze-dry to obtain a solid flocculant.

2. The preparation method according to claim 1, wherein: Preparation of quaternary ammonium salt anemone-like nano-flocculant intermediates: Add KI to a flask, introduce nitrogen to remove oxygen from the apparatus, add N,N-dimethylhexadecylamine and (3-aminopropyl)trimethoxysilane under magnetic stirring, use methanol as the solvent, reflux under condensation at 50-70°C for 12-28 hours, and allow the reaction to cool naturally after completion. Remove excess solvent by rotary evaporation and recrystallize to obtain 3-(trimethoxysilyl)propyl-n-hexadecyldimethylammonium iodide. The mass volume ratio of KI to (3-aminopropyl)trimethoxysilane is 0.1g~2ml-4ml; The volume ratio of the N,N-dimethylhexadecylamine and (3-aminopropyl)trimethoxysilane is 1-3:

1.

3. The preparation method according to claim 2, wherein: The temperature of the methanol condensation reflux is 70°C and the time is 24 hours; the recrystallization solvent is an acetone-methanol mixture with a volume ratio of 1:

1.

4. The preparation method according to claim 1, wherein: Preparation of imidazole salt anemone-like nano-flocculant intermediates: n-Dodecyl imidazole and (3-chloropropyl)trimethoxysilane were added to a flask with toluene as the solvent. The flask was sealed and nitrogen was introduced. The reaction mixture was heated under reflux at 80-110°C for 24-72 hours under magnetic stirring. After the reaction was completed, the mixture was naturally cooled and the excess solvent was removed by rotary evaporation. The resulting viscous liquid was washed with diethyl ether and dried in vacuo to obtain 1-dodecyl-3-[3-(trimethoxysilyl)propyl]-1-chloroimidazole. The molar ratio of n-dodecyl imidazole to (3-chloropropyl) trimethoxysilane is 1-2:

1.

5. The preparation method according to claim 4, characterized in that: The toluene is heated under reflux at 100° C. for 48 h.

6. The preparation method according to claim 1, wherein: In S2, the volume ratio of methanol to water in the methanol-water solution is 9:1; In S2, the pH value was adjusted to 2.2 with dilute sulfuric acid; in S3, the pH value was adjusted to 2.2 for the first time and to 3.5 for the second time with dilute sulfuric acid.

7. The preparation method according to claim 1, wherein: In S2, the condensation reflux temperature of the methanol aqueous solution is 80°C.

8. The preparation method according to claim 1, wherein: In S3, an Al2(SO4)3 aqueous solution was added to make the [Si]:[Al] molar ratio 1:10; and a NaOH aqueous solution was added to make the [Al]:[OH] molar ratio 1:

1.

9. The preparation method according to claim 1, wherein: In S3, the stirring and aging time at room temperature is 12 h; it needs to be frozen in the refrigerator for 12-24 h before freeze-drying; the freeze-drying temperature is -55℃~-40℃, and the freeze-drying time is 3-6 h.

10. A self-assembled sea anemone-like nano-flocculant obtained by the preparation method according to claim 1.

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