Composite Coagulant and Method for Treating Magnetic Resin High-Salt Organic Wastewater

Abstract

The present invention discloses a composite coagulant and a method for treating magnetic resin high-salt organic wastewater, belonging to the technical field of wastewater treatment preparation. The composite coagulant is composed of the following components in parts by weight: 50-70 parts of polyaluminum chloride, 10-20 parts of organic coagulant, 5-10 parts of coagulant aid, 10-20 parts of deionized water, and 2-4 parts of phosphate buffer solution. Among them, the organic coagulant is prepared from microcrystalline cellulose, 5-bromovaleryl chloride, tetradecyldimethyl tertiary amine, and sodium polyacrylate, and the coagulant aid is prepared from lactic acid, trifluoroacetic acid, laurylamine, and sodium lignosulfonate. The composite coagulant prepared by this method can effectively reduce the content of organic matter during the treatment of magnetic resin high-salt organic wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment preparation, and particularly relates to a composite coagulant and a method for treating high-salt organic wastewater of magnetic resin with the composite coagulant. Background Art

[0002] With the acceleration of the industrialization process and the improvement of environmental protection awareness, wastewater treatment has become an important topic in the current environmental field. High-salt organic wastewater of magnetic resin, as a typical industrial wastewater, has attracted much attention due to its complex composition and high treatment difficulty. This kind of wastewater mainly comes from the production and use process of magnetic resin, which contains high concentrations of salts, organic substances and possibly residual magnetic particles, posing a serious threat to the environment and ecological system. Therefore, developing efficient, economical and environmentally friendly wastewater treatment technologies, especially for the treatment of high-salt organic wastewater of magnetic resin, has great practical significance.

[0003] In the treatment of high-salt organic wastewater of magnetic resin, the application of composite coagulants is particularly important. The high-salt environment significantly inhibits the growth and activity of microorganisms, making traditional biological treatment methods ineffective. At the same time, the organic substances and magnetic particles in the wastewater also increase the treatment difficulty. Composite coagulants can effectively remove suspended particles and colloidal substances in the wastewater through their unique coagulation mechanism, reducing the turbidity and chromaticity of the wastewater. In addition, it can also chemically react with the organic substances in the wastewater, converting them into substances that are easy to precipitate or filter, thereby further purifying the water quality.

[0004] Patent CN109987687B discloses a composite coagulant and its preparation method and application. It uses chitosan as the raw material, and conducts sulfation reaction and nucleophilic reaction on chitosan in sequence to obtain the composite coagulant. The composite coagulant of this invention contains abundant functional groups such as hydroxyl groups, amino groups, sulfate groups and a loose porous structure, has extremely strong adsorption bridging ability, and has good flocculation, coagulation and adsorption properties. However, there is still room for improvement in the removal effect of the composite adsorbent prepared by this method on the organic substances in the wastewater. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite coagulant and a method for treating high-salt organic wastewater of magnetic resin with the composite coagulant, so as to solve the technical problem that the existing composite coagulant has poor effect in removing organic substances.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The present invention provides a composite coagulant, which is composed of the following components in parts by weight: 50-70 parts of polyaluminum chloride, 10-20 parts of organic coagulant, 5-10 parts of coagulant aid, 10-20 parts of deionized water, and 2-4 parts of phosphate buffer solution. Among them, the organic coagulant is prepared from microcrystalline cellulose, 5-bromovaleryl chloride, tetradecyldimethyl tertiary amine, and sodium polyacrylate, and the coagulant aid is prepared from lactobionic acid, trifluoroacetic acid, laurylamine, and sodium lignosulfonate.

[0008] Preferably, the preparation method of the organic coagulant includes the following steps:

[0009] Q1: After vacuum-drying microcrystalline cellulose, add it to a container filled with N,N-dimethylacetamide, stir and heat, then add 5-bromovaleryl chloride to the container, stir and react, then pour it into ethanol for stirring, centrifuge, dissolve the lower-layer precipitate, precipitate, and repeat the operation to obtain intermediate 1;

[0010] Q2: Add intermediate 1 to a container filled with N,N-dimethylacetamide, heat and stir, then add tetradecyldimethyl tertiary amine, react, dialyze, and rotary evaporate and concentrate to obtain intermediate 2;

[0011] Q3: Add intermediate 2 to deionized water, ultrasonically stir to obtain a mixed solution, then add sodium polyacrylate to deionized water, stir to obtain a sodium polyacrylate solution, then slowly add the mixed solution to the sodium polyacrylate solution, stir, ripen, and filter to obtain the organic coagulant.

[0012] In the above process, using microcrystalline cellulose as the raw material and 5-bromovaleryl chloride as the esterification reagent, intermediate 1 is prepared through a heterogeneous reaction. Subsequently, tetradecyldimethyl tertiary amine reacts with intermediate 1 to prepare intermediate 2 containing a quaternary ammonium salt structure, and intermediate 2 undergoes electrostatic complexation with sodium polyacrylate to prepare the organic coagulant. Among them, the synthesis reaction formula of intermediate 2 is as follows:

[0013]

[0014] Preferably, in Q1, the dosage ratio of microcrystalline cellulose, N,N-dimethylacetamide, and 5-bromovaleryl chloride is (0.5-0.75) g:(25-40) mL:(1-1.5) g, the vacuum drying temperature is 90-95 °C, the drying time is 20-24 h, the stirring and heating temperature is 50-80 °C, the heating time is 30-45 min, the stirring reaction time is 2-5 h, the centrifugation speed is 10000-12000 rpm, the centrifugation time is 10-15 min, dissolve it in N,N-dimethylacetamide, precipitate it in ethanol, and repeat the operation 3-5 times.

[0015] Preferably, in Q2, the dosage ratio of intermediate 1, N,N-dimethylacetamide and tetradecyldimethylamine is (2.5 - 5) g : (100 - 180) mL : (5 - 12) mL. The heating and stirring reaction temperature is 50 - 70 °C, the stirring time is 3 - 5 h, the reaction time is 4 - 6 h, the molecular retention volume of the dialysis bag during the dialysis process is 3500 Da, and it is added to ethanol for dialysis, and the ethanol is replaced every 12 h, and the dialysis time is 4 - 6 days; in Q3, the dosage ratio of intermediate 2 and sodium polyacrylate is (3 - 4.5) g : (2 - 2.4) g, the stirring time is 1 - 2 h, and the curing time is 2 - 4 h.

[0016] Preferably, the preparation method of the coagulant aid includes the following steps:

[0017] S1: Add lactic acid to a container filled with methanol, heat and stir to dissolve, then add trifluoroacetic acid, raise the temperature for reaction. After the reaction ends, perform rotary evaporation, vacuum drying, dissolution, continue to raise the temperature for reaction, and obtain compound A after the reaction ends;

[0018] S2: Add compound A to a container filled with methanol, dissolve laurylamine with methanol and slowly drop it into the container, raise the temperature for reaction. After the reaction ends, perform rotary evaporation and concentration, cool, crystallize, filter, wash, and vacuum dry to obtain compound B;

[0019] S3: Add compound B to sodium lignosulfonate, add ammonium persulfate during stirring, heat for reaction. After the reaction ends, filter, concentrate, precipitate, and wash to obtain the coagulant aid.

[0020] In the above process, lactic acid reacts under the catalysis of trifluoroacetic acid to prepare compound A, then compound A undergoes an amidation reaction with laurylamine to prepare compound B, and compound B and sodium lignosulfonate undergo a polymerization reaction under the action of ammonium persulfate to prepare the coagulant aid. Among them, the synthesis reaction formula of compound B is as follows:

[0021]

[0022] The mass spectrometry analysis results of compound A are: m / z: 340.10 (100.0%), 341.10 (13.4%), 342.10(2.3%); the mass spectrometry analysis results of compound B are: m / z: 525.31 (100.0%), 526.32 (26.9%), 527.32(5.8%).

[0023] Preferably, in S1, the dosage ratio of lactic acid, methanol and trifluoroacetic acid is (1 - 1.2) g : (40 - 48) mL : (0.2 - 0.22) mL. The heating and stirring dissolution temperature is 40 - 45°C, the temperature for the temperature-rising reaction is 50 - 55°C, the reaction time is 6 - 8 h, the vacuum drying temperature is 60 - 65°C. It is added to methanol for dissolution, and then the temperature for the continued temperature-rising reaction is 60 - 65°C, and the reaction time is 6 - 8 h. In S2, the dosage ratio of compound A and laurylamine is (1 - 1.3) g : (0.45 - 0.62) g, the temperature for the temperature-rising reaction is 60 - 65°C, the reaction time is 6 - 8 h, and it is washed with acetone and ether. In S3, the dosage ratio of compound B, sodium lignosulfonate and ammonium persulfate is (1 - 2.5) g : (1 - 1.2) g : (0.023 - 0.028) g, the heating reaction temperature is 40 - 45°C, and the reaction time is 5 - 7 h.

[0024] Preferably, the preparation method of the composite coagulant includes the following steps:

[0025] Step 1: Add polyaluminum chloride to deionized water, stir and dissolve to obtain an inorganic mixture.

[0026] Step 2: Add the organic coagulant to the inorganic mixture, continue stirring, then add the coagulant aid, adjust the pH to 7 - 7.2 with phosphate buffer solution, continuously stir, stand for 4 - 6 h, and filter to obtain the composite coagulant.

[0027] Preferably, the method for treating high-salt organic wastewater of magnetic resin by the composite coagulant includes the following steps: Add the composite coagulant to the high-salt organic wastewater of magnetic resin, fully stir and mix, carry out coagulation reaction, centrifuge to obtain high-salt wastewater, filter with attapulgite membrane to obtain a clarified filtrate, and conduct water quality detection and discharge.

[0028] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0029] 1. The present invention first uses microcrystalline cellulose, 5-bromovaleryl chloride, tetradecyldimethyl tertiary amine and sodium polyacrylate as raw materials to prepare an organic coagulant. Subsequently, lactic acid, trifluoroacetic acid, laurylamine and sodium lignosulfonate are used as raw materials to prepare a coagulant aid. Adding the organic coagulant and the coagulant aid to the preparation process of the composite coagulant can effectively remove the organic matter in the wastewater.

[0030] 2. In the process of preparing the composite coagulant of the present invention, an organic coagulant is added. The addition of this substance can effectively remove the organic matter in the wastewater and enable the composite coagulant to still maintain high coagulation performance in a high-salt environment. The intermediate 2 in the formation process of the organic coagulant contains a quaternary ammonium salt structure, which has strong cationic characteristics and can adsorb negatively charged organic matter through electrostatic interaction. As an anionic polymer, sodium polyacrylate can aggregate organic matter particles through bridging action to form larger flocs, which is convenient for removal. Moreover, the hydrolysis of polyaluminum chloride will generate polynuclear hydroxyaluminum ions, which can compress the double electric layer of colloidal particles through electro-neutralization action and promote particle aggregation. The combined use of the organic coagulant and polyaluminum chloride can simultaneously exert the functions of electro-neutralization, adsorption bridging, and network sweeping, significantly improving the removal efficiency of organic matter. At the same time, the quaternary ammonium salt structure in the organic coagulant is not easily interfered by the ionic strength in a high-salt environment and can still effectively adsorb negatively charged substances. The carboxyl group of sodium polyacrylate can still combine with organic matter through hydrogen bonds and van der Waals forces in a high-salt environment and play a bridging role, enabling it to still maintain excellent organic matter removal rate in a high-salt environment.

[0031] 3. Adding the prepared coagulant aid to the composite coagulant of the present invention can effectively improve the removal efficiency of the composite coagulant for organic matter. The polymer chain of the coagulant aid can aggregate small particle pollutants in the wastewater through adsorption bridging action to form larger flocs. The sulfonic acid group and carboxyl group contained can combine with positively charged pollutants through electrostatic interaction to achieve electro-neutralization. The addition of the coagulant aid can also improve the stability of the composite coagulant in a high-salt environment. The polymer chain contained can still combine with pollutants through hydrogen bonds and van der Waals forces in a high-salt environment and play an adsorption bridging role, thereby enhancing the mechanical strength of the flocs and making them not easily broken during stirring and sedimentation and easy to separate. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0033] Figure 1 It is a picture of the magnetic resin high-salt organic wastewater before precipitation treatment;

[0034] Figure 2 It is a picture of the magnetic resin high-salt organic wastewater after 10 minutes of coagulation precipitation treatment with the composite coagulant and 3 minutes of centrifugal separation;

[0035] Figure 3It is a picture of magnetic resin high-salt organic wastewater after being treated by coagulation and precipitation with a composite coagulant twice for 10 minutes and centrifugal separation for 3 minutes. Detailed implementation manners

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] Example 1: This example discloses a preparation method of an organic coagulant, including the following steps:

[0038] Q1: Add 0.625 g of microcrystalline cellulose after vacuum drying at 90 °C for 24 h to a container containing 32.5 mL of N,N-dimethylacetamide, stir and heat at 60 °C for 45 min, then add 1.25 g of 5-bromovaleryl chloride to the container, stir and react for 5 h, pour it into ethanol for stirring, centrifuge at 12000 rpm for 10 min, add the lower layer precipitate to N,N-dimethylacetamide for dissolution, add it to ethanol for precipitation, and repeat the operation 3 times to obtain intermediate 1;

[0039] Q2: Add 3.75 g of intermediate 1 to a container containing 140 mL of N,N-dimethylacetamide, heat and stir at 60 °C for 4 h, then add 8.5 mL of tetradecyldimethyl tertiary amine, react for 6 h, perform dialysis, the molecular cut-off amount of the dialysis bag during dialysis is 3500 Da, add it to ethanol for dialysis, change ethanol every 12 h, the dialysis time is 6 days, and perform rotary evaporation and concentration to obtain intermediate 2;

[0040] Q3: Add 3.75 g of intermediate 2 to 10 mL of deionized water, stir ultrasonically to obtain a mixed solution, then add 2.2 g of sodium polyacrylate to 10 mL of deionized water, stir to obtain a sodium polyacrylate solution, then slowly add the mixed solution to the sodium polyacrylate solution, stir for 2 h, age for 4 h, and filter to obtain the organic coagulant.

[0041] This example discloses a preparation method of a coagulant aid, including the following steps:

[0042] S1: Add 1.1 g of lactic acid to a container containing 44 mL of methanol, heat and stir to dissolve at 45 °C, then add 0.21 mL of trifluoroacetic acid, raise the temperature to 55 °C and react for 8 h. After the reaction, perform rotary evaporation, vacuum dry at 65 °C, add it to methanol for dissolution, continue to raise the temperature to 65 °C and react for 8 h. After the reaction, obtain compound A;

[0043] S2: Add 1.15 g of compound A into a container filled with 30 mL of methanol. Dissolve 0.53 g of laurylamine in 10 mL of methanol and slowly add it dropwise into the container. Heat up to 65 °C and react for 8 h. After the reaction is completed, concentrate by rotary evaporation, cool, crystallize, filter, wash with acetone and ether, and dry under vacuum to obtain compound B;

[0044] S3: Add 1.75 g of compound B into 1.1 g of sodium lignosulfonate. Add 0.025 g of ammonium persulfate during stirring, heat and react at 45 °C for 7 h. After the reaction is completed, filter, concentrate, precipitate, and wash to obtain a coagulant aid.

[0045] This example discloses a composite coagulant, which is composed of the following components in parts by weight: 60 parts of polyaluminum chloride, 15 parts of organic coagulant, 7.5 parts of coagulant aid, 15 parts of deionized water, and 3 parts of phosphate buffer solution.

[0046] This example discloses a preparation method of a composite coagulant, which includes the following steps:

[0047] Step 1: Add polyaluminum chloride into deionized water, stir and dissolve to obtain an inorganic mixture;

[0048] Step 2: Add the organic coagulant into the inorganic mixture, continue to stir, then add the coagulant aid, adjust the pH = 7 with phosphate buffer solution, continuously stir, stand for 6 h, and filter to obtain the composite coagulant.

[0049] Example 2: This example discloses a preparation method of an organic coagulant, which includes the following steps:

[0050] Q1: Add 0.5 g of microcrystalline cellulose after vacuum drying at 90 °C for 24 h into a container filled with 25 mL of N,N-dimethylacetamide, stir and heat at 60 °C for 45 min, then add 1.5 g of 5-bromovaleryl chloride into the container, stir and react for 5 h, pour it into ethanol for stirring, centrifuge at 12000 rpm for 10 min, add the lower layer precipitate into N,N-dimethylacetamide for dissolution, and add it into ethanol for precipitation. Repeat the operation 3 times to obtain intermediate 1;

[0051] Q2: Add 2.5 g of intermediate 1 into a container filled with 100 mL of N,N-dimethylacetamide, heat and stir at 60 °C for 4 h, then add 5 mL of tetradecyldimethylamine, react for 6 h, perform dialysis. The molecular cut-off amount of the dialysis bag during dialysis is 3500 Da, add it into ethanol for dialysis, change ethanol every 12 h, the dialysis time is 6 days, and concentrate by rotary evaporation to obtain intermediate 2;

[0052] Q3: Add 3 g of intermediate 2 to 10 mL of deionized water, and obtain a mixed solution after ultrasonic stirring. Subsequently, add 2 g of sodium polyacrylate to 10 mL of deionized water, and obtain a sodium polyacrylate solution after stirring. Then, slowly add the mixed solution to the sodium polyacrylate solution, stir for 2 h, age for 4 h, and filter to obtain an organic coagulant.

[0053] This example discloses a preparation method of a coagulant aid, which includes the following steps:

[0054] S1: Add 1 g of lactobionic acid to a container containing 40 mL of methanol, heat and stir to dissolve at 45 °C. Subsequently, add 0.2 mL of trifluoroacetic acid, raise the temperature to 55 °C and react for 8 h. After the reaction ends, perform rotary evaporation, vacuum dry at 65 °C, add it to methanol for dissolution, continue to raise the temperature to 65 °C and react for 8 h. After the reaction ends, obtain compound A;

[0055] S2: Add 1 g of compound A to a container containing 30 mL of methanol. Dissolve 0.45 g of laurylamine in 10 mL of methanol and slowly add it dropwise to the container. Raise the temperature to 65 °C and react for 8 h. After the reaction ends, perform rotary evaporation and concentration, cool, crystallize, filter, wash with acetone and ether, and vacuum dry to obtain compound B;

[0056] S3: Add 1 g of compound B to 1 g of sodium lignosulfonate, add 0.023 g of ammonium persulfate during stirring, heat and react at 45 °C for 7 h. After the reaction ends, filter, concentrate, precipitate, and wash to obtain the coagulant aid.

[0057] This example discloses a composite coagulant, which is composed of the following components in parts by weight: 50 parts of polyaluminum chloride, 10 parts of organic coagulant, 5 parts of coagulant aid, 10 parts of deionized water, and 2 parts of phosphate buffer solution.

[0058] This example discloses a preparation method of a composite coagulant, which includes the following steps:

[0059] Step 1: Add polyaluminum chloride to deionized water, stir and dissolve to obtain an inorganic mixed solution;

[0060] Step 2: Add the organic coagulant to the inorganic mixed solution, continue to stir, then add the coagulant aid, adjust the pH = 7 with phosphate buffer solution, continuously stir, stand for 6 h, filter to obtain the composite coagulant.

[0061] Example 3: This example discloses a preparation method of an organic coagulant, which includes the following steps:

[0062] Q1: After vacuum drying 0.75 g of microcrystalline cellulose at 90 °C for 24 h, it was added to a container containing 40 mL of N,N-dimethylacetamide, and stirred and heated at 60 °C for 45 min. Then, 1 g of 5-bromovaleryl chloride was added to the container, and after stirring and reacting for 5 h, it was poured into ethanol and stirred. Centrifuged at 12000 rpm for 10 min, the lower layer precipitate was added to N,N-dimethylacetamide for dissolution, and then added to ethanol for precipitation. The operation was repeated 3 times to obtain Intermediate 1;

[0063] Q2: 5 g of Intermediate 1 was added to a container containing 180 mL of N,N-dimethylacetamide, and after heating and stirring at 60 °C for 4 h, 12 mL of tetradecyldimethylamine was added, and the reaction was carried out for 6 h. Dialysis was carried out, and the molecular cut-off of the dialysis bag during the dialysis process was 3500 Da. It was added to ethanol for dialysis, and the ethanol was replaced every 12 h. The dialysis time was 6 days, and then rotary evaporation and concentration were carried out to obtain Intermediate 2;

[0064] Q3: 4.5 g of Intermediate 2 was added to 10 mL of deionized water, and after ultrasonic stirring, a mixed solution was obtained. Subsequently, 2.4 g of sodium polyacrylate was added to 10 mL of deionized water, and after stirring, a sodium polyacrylate solution was obtained. Then, the mixed solution was slowly added to the sodium polyacrylate solution, stirred for 2 h, aged for 4 h, and filtered to obtain an organic coagulant.

[0065] This example discloses a preparation method of a coagulant aid, which includes the following steps:

[0066] S1: 1.2 g of lactobionic acid was added to a container containing 48 mL of methanol, heated and stirred for dissolution at 45 °C, then 0.22 mL of trifluoroacetic acid was added, and the temperature was raised to 55 °C for reaction for 8 h. After the reaction was completed, rotary evaporation was carried out, vacuum drying was carried out at 65 °C, added to methanol for dissolution, and the temperature was further raised to 65 °C for reaction for 8 h. After the reaction was completed, Compound A was obtained;

[0067] S2: 1.3 g of Compound A was added to a container containing 30 mL of methanol, 0.62 g of laurylamine was dissolved in 10 mL of methanol and slowly added dropwise to the container, and the temperature was raised to 65 °C for reaction for 8 h. After the reaction was completed, rotary evaporation and concentration were carried out, cooled, crystallized, filtered, washed with acetone and ether, and vacuum dried to obtain Compound B;

[0068] S3: 2.5 g of Compound B was added to 1.2 g of sodium lignosulfonate, 0.028 g of ammonium persulfate was added during stirring, and the reaction was carried out at 45 °C for 7 h. After the reaction was completed, filtration, concentration, precipitation, and washing were carried out to obtain the coagulant aid.

[0069] This example discloses a composite coagulant, which is composed of the following components in parts by weight: 70 parts of polyaluminum chloride, 20 parts of organic coagulant, 10 parts of coagulant aid, 20 parts of deionized water, and 4 parts of phosphate buffer solution.

[0070] This embodiment discloses a preparation method of a composite coagulant, which includes the following steps:

[0071] Step 1: Add polyaluminum chloride to deionized water, stir and dissolve it to obtain an inorganic mixture.

[0072] Step 2: Add an organic coagulant to the inorganic mixture, continue stirring, then add a coagulant aid, adjust the pH to 7 with phosphate buffer solution, continuously stir, let it stand for 6 h, filter to obtain the composite coagulant.

[0073] Example 4: This embodiment discloses a preparation method of an organic coagulant, which includes the following steps:

[0074] Q1: After vacuum drying 0.6 g of microcrystalline cellulose at 90 °C for 24 h, add it to a container containing 30 mL of N,N-dimethylacetamide, stir and heat at 60 °C for 45 min, then add 1.1 g of 5-bromovaleryl chloride to the container, stir and react for 5 h, pour it into ethanol and stir, centrifuge at 12000 rpm for 10 min, add the lower layer precipitate to N,N-dimethylacetamide to dissolve it, add it to ethanol for precipitation, repeat the operation 3 times to obtain Intermediate 1.

[0075] Q2: Add 3 g of Intermediate 1 to a container containing 120 mL of N,N-dimethylacetamide, heat and stir at 60 °C for 4 h, then add 6 mL of tetradecyldimethylamine, react for 6 h, perform dialysis, the molecular retention volume of the dialysis bag during dialysis is 3500 Da, add it to ethanol for dialysis, change ethanol every 12 h, the dialysis time is 6 days, rotary evaporate and concentrate to obtain Intermediate 2.

[0076] Q3: Add 3.5 g of Intermediate 2 to 10 mL of deionized water, stir ultrasonically to obtain a mixture, then add 2.1 g of sodium polyacrylate to 10 mL of deionized water, stir to obtain a sodium polyacrylate solution, then slowly add the mixture to the sodium polyacrylate solution, stir for 2 h, cure for 4 h, filter to obtain the organic coagulant.

[0077] This embodiment discloses a preparation method of a coagulant aid, which includes the following steps:

[0078] S1: Add 1.05 g of lactobionic acid to a container containing 42 mL of methanol, heat and stir to dissolve it at 45 °C, then add 0.21 mL of trifluoroacetic acid, raise the temperature to 55 °C and react for 8 h. After the reaction, perform rotary evaporation, vacuum dry at 65 °C, add it to methanol to dissolve it, continue to raise the temperature to 65 °C and react for 8 h. After the reaction, obtain Compound A.

[0079] S2: Add 1.1 g of compound A into a container filled with 30 mL of methanol. Dissolve 0.48 g of laurylamine in 10 mL of methanol and slowly add it dropwise into the container. Heat up to 65 °C and react for 8 h. After the reaction is completed, perform rotary evaporation and concentration, cool down, crystallize, filter, wash with acetone and ether, and dry under vacuum to obtain compound B;

[0080] S3: Add 1.5 g of compound B into 1.05 g of sodium lignosulfonate. Add 0.024 g of ammonium persulfate during stirring, heat and react at 45 °C for 7 h. After the reaction is completed, filter, concentrate, precipitate, and wash to obtain a coagulant aid.

[0081] This example discloses a composite coagulant, which is composed of the following components in parts by weight: 55 parts of polyaluminum chloride, 12 parts of organic coagulant, 6 parts of coagulant aid, 12 parts of deionized water, and 2.5 parts of phosphate buffer solution.

[0082] This example discloses a preparation method of a composite coagulant, including the following steps:

[0083] Step 1: Add polyaluminum chloride into deionized water, stir and dissolve to obtain an inorganic mixture;

[0084] Step 2: Add the organic coagulant into the inorganic mixture, continue to stir, then add the coagulant aid, adjust the pH = 7 with phosphate buffer solution, continuously stir, let stand for 6 h, filter to obtain the composite coagulant.

[0085] Example 5: This example discloses a preparation method of an organic coagulant, including the following steps:

[0086] Q1: Add 0.72 g of microcrystalline cellulose after vacuum drying at 90 °C for 24 h into a container filled with 27 mL of N,N-dimethylacetamide, stir and heat at 60 °C for 45 min, then add 1.4 g of 5-bromovaleryl chloride into the container, stir and react for 5 h, pour it into ethanol for stirring, centrifuge at 12000 rpm for 10 min, add the lower-layer precipitate into N,N-dimethylacetamide for dissolution, add it into ethanol for precipitation, and repeat the operation 3 times to obtain intermediate 1;

[0087] Q2: Add 4 g of intermediate 1 into a container filled with 160 mL of N,N-dimethylacetamide, heat and stir at 60 °C for 4 h, then add 10 mL of tetradecyldimethylamine, react for 6 h, perform dialysis, the molecular cut-off amount of the dialysis bag during dialysis is 3500 Da, add it into ethanol for dialysis, change the ethanol every 12 h, the dialysis time is 6 days, perform rotary evaporation and concentration to obtain intermediate 2;

[0088] Q3: Add 4.2 g of intermediate 2 to 10 mL of deionized water, stir ultrasonically to obtain a mixed solution, then add 2.3 g of sodium polyacrylate to 10 mL of deionized water, stir to obtain a sodium polyacrylate solution, and then slowly add the mixed solution to the sodium polyacrylate solution, stir for 2 h, age for 4 h, and filter to obtain an organic coagulant.

[0089] This example discloses a preparation method of a coagulant aid, including the following steps:

[0090] S1: Add 1.15 g of lactobionic acid to a container containing 46 mL of methanol, heat and stir to dissolve at 45 °C, then add 0.22 mL of trifluoroacetic acid, raise the temperature to 55 °C and react for 8 h. After the reaction ends, perform rotary evaporation, vacuum dry at 65 °C, add to methanol for dissolution, continue to raise the temperature to 65 °C and react for 8 h. After the reaction ends, obtain compound A;

[0091] S2: Add 1.2 g of compound A to a container containing 30 mL of methanol, dissolve 0.57 g of laurylamine in 10 mL of methanol and slowly add it dropwise to the container, raise the temperature to 65 °C and react for 8 h. After the reaction ends, perform rotary evaporation and concentration, cool, crystallize, filter, wash with acetone and ether, and vacuum dry to obtain compound B;

[0092] S3: Add 2.1 g of compound B to 1.15 g of sodium lignosulfonate, add 0.027 g of ammonium persulfate during stirring, heat and react at 45 °C for 7 h. After the reaction ends, filter, concentrate, precipitate, and wash to obtain the coagulant aid.

[0093] This example discloses a composite coagulant, which is composed of the following components in parts by weight: 65 parts of polyaluminum chloride, 18 parts of organic coagulant, 8 parts of coagulant aid, 18 parts of deionized water, and 3.5 parts of phosphate buffer solution.

[0094] This example discloses a preparation method of a composite coagulant, including the following steps:

[0095] Step 1: Add polyaluminum chloride to deionized water, stir to dissolve to obtain an inorganic mixed solution;

[0096] Step 2: Add the organic coagulant to the inorganic mixed solution, continue to stir, then add the coagulant aid, adjust the pH = 7 with phosphate buffer solution, continuously stir, stand for 6 h, and filter to obtain the composite coagulant.

[0097] Comparative Example 1: Compared with Example 1, in Comparative Example 1, during the preparation of the organic coagulant, sodium polyacrylate is not added, and other conditions remain unchanged.

[0098] Comparative Example 2: Compared with Example 1, in Comparative Example 2, during the preparation of the coagulant aid, lactobionic acid is not added, and other conditions remain unchanged.

[0099] Comparative Example 3: Compared with Example 1, in the process of preparing the composite coagulant in Comparative Example 3, no organic coagulant was added, and other conditions remained unchanged.

[0100] Comparative Example 4: Compared with Example 1, in the process of preparing the composite coagulant in Comparative Example 4, no coagulant aid was added, and other conditions remained unchanged.

[0101] Experimental Example: Take the regenerated wastewater from Beijing Road Water Plant of Huai'an Water Supply Co., Ltd. for sampling and analysis. Take 40 mL of high-salt organic wastewater water samples and add 0 μL, 10 μL, 20 μL, 50 μL, 100 μL, 150 μL, 200 μL, 250 μL, 300 μL, 350 μL, 400 μL, 450 μL, 500 μL, 550 μL, 600 μL, 650 μL, 700 μL, 750 μL, 800 μL, 850 μL, 900 μL, 950 μL of the composite coagulant prepared according to Example 1. After coagulation and precipitation for 10 min and centrifugal separation for 3 min, measure the absorbance, TOC, COD mn and the peak area of organic matter in the liquid phase of 1000 Da - 10000 Da. The test results are shown in Table 1:

[0102] Table 1

[0103]

[0104] It can be seen from the test results in Table 1 that with the addition of the composite coagulant, the absorbance, TOC, COD mn of the high-salt organic wastewater water sample and the peak area of organic matter in the liquid phase of 1000 Da - 10000 Da have all decreased, indicating that the composite coagulant prepared by this method can effectively remove the pollutants in the high-salt organic wastewater water sample.

[0105] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

[0106] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to only the specific embodiments. Obviously, according to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principle and practical application of the present invention, so that those skilled in the art in the relevant technical field can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. Composite coagulant, characterized in that, It consists of the following components in parts by weight: 50 - 70 parts of polyaluminum chloride, 10 - 20 parts of organic coagulant, 5 - 10 parts of coagulant aid, 10 - 20 parts of deionized water, 2 - 4 parts of phosphate buffer solution. Among them, the organic coagulant is prepared from microcrystalline cellulose, 5 - bromovaleryl chloride, tetradecyldimethyl tertiary amine and sodium polyacrylate. Using microcrystalline cellulose as the raw material and 5 - bromovaleryl chloride as the esterification reagent, intermediate 1 is prepared through a heterogeneous reaction. Subsequently, tetradecyldimethyl tertiary amine reacts with intermediate 1 to prepare intermediate 2 containing a quaternary ammonium salt structure. Intermediate 2 undergoes electrostatic complexation with sodium polyacrylate to prepare the organic coagulant; the coagulant aid is prepared from lactic acid, trifluoroacetic acid, laurylamine and sodium lignosulfonate. Under the catalytic action of trifluoroacetic acid, lactic acid reacts to prepare compound A. Then, compound A undergoes amidation reaction with laurylamine to prepare compound B. Compound B and sodium lignosulfonate undergo a polymerization reaction under the action of ammonium persulfate to prepare the coagulant aid.

2. The composite coagulant according to claim 1, wherein The preparation method of the organic coagulant includes the following steps: Q1: Vacuum - dry microcrystalline cellulose and then add it to a container filled with N,N - dimethylacetamide. Stir and heat, then add 5 - bromovaleryl chloride to the container. After stirring and reacting, pour it into ethanol for stirring, centrifugation. Dissolve the lower - layer precipitate, precipitate again, and repeat the operation to obtain intermediate 1; Q2: Add intermediate 1 to a container filled with N,N - dimethylacetamide. After heating and stirring, add tetradecyldimethyl tertiary amine, react, dialyze, and rotary evaporate and concentrate to obtain intermediate 2; Q3: Add intermediate 2 to deionized water, stir ultrasonically to obtain a mixed solution. Subsequently, add sodium polyacrylate to deionized water, stir to obtain a sodium polyacrylate solution. Then, slowly add the mixed solution to the sodium polyacrylate solution, stir, age, and filter to obtain the organic coagulant.

3. The composite coagulant according to claim 2, wherein In Q1, the dosage ratio of microcrystalline cellulose, N,N - dimethylacetamide and 5 - bromovaleryl chloride is (0.5 - 0.75) g:(25 - 40) mL:(1 - 1.5) g. The vacuum - drying temperature is 90 - 95 °C, the drying time is 20 - 24 h, the stirring - heating temperature is 50 - 80 °C, the heating time is 30 - 45 min, the stirring - reaction time is 2 - 5 h, the centrifugation speed is 10000 - 12000 rpm, the centrifugation time is 10 - 15 min. Add it to N,N - dimethylacetamide for dissolution, add it to ethanol for precipitation, and repeat the operation 3 - 5 times.

4. The composite coagulant according to claim 2, wherein In the Q2, the amount ratio of the intermediate 1, N,N-dimethylacetamide and tetradecyl dimethyl tertiary amine is (2.5-5) g: (100-180) mL: (5-12) mL, the heating and stirring reaction temperature is 50-70°C, the stirring time is 3-5 hours, the reaction time is 4-6 hours, the molecular retention capacity of the dialysis bag during the dialysis process is 3500Da, it is added to ethanol for dialysis, the ethanol is replaced every 12 hours, and the dialysis time is 4-6 days; in the Q3, the amount ratio of the intermediate 2 and sodium polyacrylate is (3-4.5) g: (2-2.4) g, the stirring time is 1-2 hours, and the aging time is 2-4 hours.

5. The composite coagulant according to claim 1, characterized in that, The preparation method of the coagulant aid comprises the following steps: S1: Add lactobionic acid to a container filled with methanol, heat and stir to dissolve, then add trifluoroacetic acid, heat to react, after the reaction is completed, rotary evaporate, vacuum dry, dissolve, continue to heat to react, after the reaction is completed, obtain compound A; S2: Add compound A to a container filled with methanol, dissolve lauryl amine in methanol and slowly add it dropwise to the container, heat to react, and after the reaction is completed, evaporate and concentrate, cool, crystallize, filter, wash, and vacuum dry to obtain compound B; S3: adding compound B to sodium lignin sulfonate, adding ammonium persulfate during stirring, heating for reaction, filtering, concentrating, precipitating, washing, and obtaining a coagulant aid after the reaction is completed.

6. The composite coagulant according to claim 5, characterized in that, In S1, the dosage ratio of lactobionic acid, methanol and trifluoroacetic acid is (1-1.2) g: (40-48) mL: (0.2-0.22) mL, the heating and stirring dissolution temperature is 40-45°C, the temperature of the temperature rise reaction is 50-55°C, the reaction time is 6-8h, the vacuum drying temperature is 60-65°C, and the mixture is added to methanol for dissolution, and the temperature of the temperature rise reaction is continued to be 60-65°C, and the reaction time is 6-8h; in S2, the The amount ratio of compound A and lauryl amine is (1-1.3) g: (0.45-0.62) g, the heating reaction temperature is 60-65°C, the reaction time is 6-8h, and washing is carried out with acetone and ether; in S3, the amount ratio of compound B, sodium lignin sulfonate and ammonium persulfate is (1-2.5) g: (1-1.2) g: (0.023-0.028) g, the heating reaction temperature is 40-45°C, and the reaction time is 5-7h.

7. The preparation method of the composite coagulant according to any one of claims 1-6, characterized in that, The following steps are involved: Step 1: Add polyaluminium chloride into deionized water, stir and dissolve to obtain an inorganic mixed solution; Step 2: Add the organic coagulant to the inorganic mixed solution, continue stirring, then add the coagulant aid, adjust the pH to 7-7.2 with phosphate buffer, continue stirring, let stand for 4-6 hours, filter, and obtain a composite coagulant.

8. The method for treating high-salt organic wastewater of magnetic resin by using the composite coagulant according to any one of claims 1-6, characterized in that, The following steps are involved: The composite coagulant is added to the magnetic resin high-salt organic wastewater, fully stirred and mixed, coagulated and centrifuged to obtain high-salt wastewater, which is filtered using a convex rod membrane to obtain a clarified filtrate, and then the water quality is tested and discharged.

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