Ultrafiltration membrane pollution and blockage treatment method, pollution and blockage treatment agent and preparation method

Abstract

The invention provides an ultrafiltration membrane pollution and blockage treatment method, a pollution and blockage treatment agent and a preparation method, and the preparation method comprises the following steps: S1, putting monomer tetraallylammonium chloride into a reaction kettle, and adding water to prepare a tetraallylammonium chloride aqueous solution with the mass fraction of 60-75%; s2, adding an initiator accounting for 0.01-1% of the mass fraction of the monomer to prepare a reaction solution; s3, stirring and heating the reaction liquid to initiate a free radical polymerization reaction; s4, adding a reducing agent to terminate the polymerization reaction, and cooling to obtain a colloidal polytetraallylammonium chloride polymer; and S5, diluting the polymer with water to prepare a polytetraallylammonium chloride aqueous solution, adding a bactericide and a chelating agent, and adjusting the pH value to obtain the sewage plugging treatment agent. Through a green synthesis method and a multifunctional formula design, an efficient water treatment effect is realized. The method has the advantages of being easy and convenient to operate, environmentally friendly and high in economical efficiency, and is suitable for various water treatment application scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and specifically relates to a method for treating ultrafiltration membrane fouling, a fouling treatment agent and a preparation method thereof. Background Art

[0002] Ultrafiltration membrane technology is a separation technology based on the principle of physical sieving. It intercepts macromolecular substances (such as proteins, colloids, bacteria) and suspended particles in water through micropores (pore size 1-100 nanometers) on the membrane surface, and allows water and small molecular substances (such as salt ions) to pass through. It has been widely used in industrial and civil water treatment. However, due to various pollutants present in water, such as organic matter, microorganisms, metal ions, colloids, etc., it is easy to cause concentration polarization of the ultrafiltration membrane during water production, resulting in fouling on the membrane surface, affecting the membrane flux and the stability of the system operation. Among them, the most common ones are PAC and polyacrylamide. Higher residues of PAC or polyacrylamide in the influent will seriously foul the ultrafiltration membrane.

[0003] Traditional treatment methods often require frequent chemical cleaning to restore the membrane flux, which increases the operating cost while reducing the service life of the membrane. Therefore, developing a new type of pre-treatment water treatment agent before the membrane to improve the anti-fouling performance of the ultrafiltration membrane has become a research hotspot. At present, poly(dimethyldiallylammonium chloride) has been reported as an efficient flocculant for sewage treatment, and its excellent flocculation effect has attracted the attention of researchers at home and abroad. However, its preparation process has high requirements for the purity of raw material monomers, and defects such as low yield lead to high prices. Later, Tajima, Teffrey, Welcher and others studied the preparation process and the types of initiators (using azo or organic peroxides), and prepared copolymers with relatively high viscosity and high molecular weight. However, due to reasons such as the storage stability of the initiator and the limited industrial conditions of the preparation process, it has not been industrially produced; Zhang Yuejun et al. from Nanjing University of Science and Technology used sodium persulfate as an initiator and introduced EDTA4Na during the reaction process to prepare a copolymer with a high molecular weight. However, poly(dimethyldiallylammonium chloride) needs to be mixed with PAC for use, and the flocculation effect significantly deteriorates after more than 15 days, and the product shelf life is short.

[0004] Problems existing in current poly(dimethyldiallylammonium chloride) high molecular flocculants are as follows:

[0005] 1. The temperature during the product preparation process is as high as 105-110 °C, and the reaction time is as long as 72 h;

[0006] 2. The flocculation process needs to be used in combination with PAC to show the flocculation effect.

[0007] 3. The product shelf life is short. Microorganisms grow in water after more than 15 days, and the flocculation effect deteriorates.

[0008] 4. It is expensive and limited in market application. Summary of the Invention

[0009] The object of the present invention is to overcome the shortcomings of the prior art and provide a preparation method and application of a fouling treatment agent. Through a specific synthesis method and formulation design, high-efficiency coagulation effect is achieved, and it has the characteristics of environmental friendliness and high economy. Specifically, it is realized through the following technical solutions:

[0010] A preparation method of a fouling treatment agent provided by the present invention includes the following steps:

[0011] S1. Place monomer tetraallylammonium chloride in a reaction kettle, and add water to prepare an aqueous solution of tetraallylammonium chloride with a mass fraction of 60 - 75%;

[0012] S2. Add an initiator accounting for 0.01 - 1% of the monomer mass fraction to the aqueous solution of tetraallylammonium chloride obtained in step S1 to form a reaction solution;

[0013] S3. Stir and heat up the reaction solution obtained in step S2 to initiate a free radical polymerization reaction;

[0014] S4. Add a reducing agent to terminate the polymerization reaction, and cool to room temperature to obtain a colloidal poly(tetraallylammonium chloride) polymer;

[0015] S5. Dilute the colloidal poly(tetraallylammonium chloride) polymer obtained in step S4 with water to prepare an aqueous solution of poly(tetraallylammonium chloride), add a bactericide and a chelating agent, and adjust the pH to 6 - 7 with AlCl3 to obtain a liquid flocculant; the liquid flocculant is the fouling treatment agent.

[0016] Optionally or preferably, in step S2, the initiator is one or more of tert-butyl hydroperoxide, butyllithium, persulfate, and azo organic compounds; the addition amount of the initiator is 0.05 - 1.5% of the mass of monomer tetraallylammonium chloride.

[0017] Optionally or preferably, in step S2, a dispersant is further added; the dispersant is polyethylene oxide PEO; the addition amount of the dispersant is 1 - 5% of the mass of monomer tetraallylammonium chloride.

[0018] Optionally or preferably, the temperature increase in step S3 is a stepwise temperature increase, specifically:

[0019] S201. Stir the reaction solution and slowly heat up until the temperature reaches 40°C;

[0020] S202. Keep the reaction temperature at 40 - 55°C, and the heat preservation time is 8 - 12 h;

[0021] S203. Continue to heat up to 65 - 75°C and maintain this temperature for 12 - 24 h until the molecular weight reaches 400,000.

[0022] Optionally or preferably, in step S4, the reducing agent is sodium metabisulfite, sulfite or bisulfite; the addition amount of the reducing agent is 0.5-3% of the mass of monomer tetraallylammonium chloride.

[0023] Optionally or preferably, in step S5, the proportion of polytetraallylammonium chloride in the liquid flocculant is 1-20%.

[0024] Optionally or preferably, in step S5, the bactericide is azoxystrobin or isothiazolinone; the proportion of the bactericide in the liquid flocculant is 0.1-10%; the chelating agent is one or more of EDTA, EDTA2Na, EDTA4Na, sodium gluconate and sodium carboxymethylcellulose; the proportion of the chelating agent in the liquid flocculant is 0.5-15%.

[0025] Optionally or preferably, in step S5, when obtaining the liquid flocculant, ultrasonic dispersion is used to ensure the homogenization of the components.

[0026] The present invention also provides a fouling treatment agent prepared by the above fouling treatment agent preparation method.

[0027] The present invention also provides an ultrafiltration membrane fouling treatment method, using the above fouling treatment agent, adding the fouling treatment agent to the sewage before the ultrafiltration membrane, reacting for 10-30 s, and then performing sand filtration treatment on the sewage.

[0028] Based on the above technical solutions, the following technical effects can be produced:

[0029] The fouling treatment agent preparation method provided by the present invention has a fast polymerization rate and a short reaction time; the provided fouling treatment agent has a strong removal ability, is universal and multifunctional, and can cope with various pollutants; the ultrafiltration membrane fouling treatment method provided has a remarkable flocculation effect, greatly improves the water treatment capacity of the ultrafiltration membrane, reduces the cleaning frequency, and reduces the chemical cost. Description of the Drawings

[0030] 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 the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0031] Figure 1 It is a flowchart of the fouling treatment agent preparation method in the present invention;

[0032] Figure 2 It is the preparation reaction general formula in the present invention. Detailed implementation mode

[0033] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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 the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0035] Embodiment 1:

[0036] As Figure 1 shown:

[0037] A method for preparing a fouling treatment agent provided in this embodiment includes the following steps:

[0038] S1. Place the polymer monomer tetraallylammonium chloride in a reaction kettle, add water to prepare an aqueous solution of tetraallylammonium chloride with a mass fraction of 60-70%, and introduce nitrogen for protection. Among them, the content of the impurity allyldimethylammonium chloride hydrochloride in the monomer is less than 500 mg / kg, other impurities are less than 30 mg / kg, and the residue of metal ions such as Cu and Fe is less than 2 mg / kg;

[0039] S2. At room temperature, add an initiator with a mass fraction of 0.01-1% of the monomer to the aqueous solution of tetraallylammonium chloride, add a dispersant, and prepare a reaction solution;

[0040] Specifically, the initiator is one or more of tert-butyl hydroperoxide, butyllithium, persulfate, and azo organic compounds.

[0041] Specifically, the addition amount of the initiator is 0.05-1.5% of the mass of the polymer monomer.

[0042] Specifically, the dispersant is polyethylene oxide PEO.

[0043] Specifically, the addition amount of the dispersant is 1-5% of the weight of the monomer tetraallylammonium chloride.

[0044] S3. Slowly heat up the reaction solution obtained in step S2 under stirring. When the temperature reaches 40°C, initiate a free radical polymerization reaction, control the reaction temperature at 40-55°C, and maintain it for 8-12 h; when the molecular weight reaches about 300,000, continue to heat up to 65-75°C and maintain it for 12-24 h.

[0045] S4. When the molecular weight reaches about 400,000, a reducing agent is added to terminate the polymerization reaction, and it is cooled to room temperature to obtain a colloidal polyallylammonium chloride polymer;

[0046] Specifically, the reducing agent is sodium metabisulfite, sulfite or bisulfite.

[0047] Specifically, the addition amount of the reducing agent is 0.5-3% of the weight of the monomer allylammonium chloride.

[0048] S5. The colloidal polymer obtained in step S4 is diluted with water to prepare an aqueous solution of polyallylammonium chloride with a specific concentration, and a bactericide and a chelating agent in a specific proportion are added. Ultrasonic dispersion is used to ensure the homogenization of the components to obtain a liquid flocculant;

[0049] Specifically, the proportion of polyallylammonium chloride in the liquid flocculant is 1-20%, preferably 5-15%.

[0050] Specifically, the bactericide in the liquid flocculant is azoxystrobin or isothiazolinone. Further, the proportion of the bactericide in the liquid flocculant is 0.1-10%.

[0051] Specifically, the chelating agent is one or a mixture of more of EDTA, EDTA2Na, EDTA4Na, sodium gluconate and sodium carboxymethylcellulose; further, the proportion of the chelating agent in the liquid flocculant is 0.5-15%, preferably 1-8%.

[0052] Example 2:

[0053] A method for preparing a fouling treatment agent provided in this example includes the following steps

[0054] S1. Place 10.6 kg of monomer allylammonium chloride in a reactor, introduce nitrogen for protection, add water to prepare an aqueous solution of allylammonium chloride with a mass fraction of 70%, in which the content of the impurity allylammonium chloride hydrochloride is less than 494 mg / kg, the residual Cu ion is 1.88 mg / kg, and the residual Fe ion is 1.92 mg / kg.

[0055] S2. At ambient temperature, add 0.1 kg of sodium persulfate to the aqueous solution of allylammonium chloride to prepare a reaction solution.

[0056] S3. Add 0.53 kg of PEO to the reaction system obtained in step S2, slowly heat it with stirring, control the reaction temperature at 40-55 °C, react for 8-12 h, and obtain the average molecular weight of the sample as 298,000 by detecting the intrinsic viscosity. Continue to raise the temperature to 65-75 °C and maintain it for 12-24 h.

[0057] S4. When the molecular weight reaches 395,000, add 0.31 kg of sodium sulfite to terminate the polymerization reaction, and cool to ambient temperature to obtain 10.5 kg of colloidal polyallylammonium chloride polymer.

[0058] S5. Add 200 kg of deionized water to the colloidal polymer obtained in step S4 to prepare an approximately 5% aqueous solution of polyallylammonium chloride. Add 6.3 kg of azoxystrobin and 10.5 kg of EDTA2Na, and adjust the pH to 7.03 with AlCl3 to obtain a colorless and transparent liquid high-efficiency flocculant, namely the fouling treatment agent.

[0059] When using the fouling treatment agent prepared in this example for ultrafiltration membrane fouling treatment:

[0060] Take 20 L of the sewage before the ultrafiltration membrane, add 0.1 g of the fouling treatment agent prepared in this example, about 5 mg / L. The turbidity before treatment is 3.44 NTU. After adding the medicine and flocculating for 20 s and then passing through the sand rate treatment, the turbidity is 0.98 NTU. The water passing volume of the filter membrane measured by the SDI device is increased from 300 mL before treatment to 2300 mL.

[0061] Example 3:

[0062] S1. Place 50.8 kg of monomer allylammonium chloride in a reactor, add water to prepare an aqueous solution with a mass fraction of 71%, and introduce nitrogen for protection. The content of the impurity allylammonium chloride hydrochloride is less than 450 mg / kg, the residual Cu ion is 1.98 mg / kg, and the residual Fe ion is 1.2 mg / kg.

[0063] S2. At ambient temperature, add 0.02 kg of tert-butyl hydroperoxide to the aqueous solution of allylammonium chloride to prepare a reaction solution.

[0064] S3. Add 0.51 kg of PEO to the reaction system obtained in step S2, slowly heat with stirring, control the reaction temperature at 40 - 55 °C, react for 8 - 12 h, and obtain the average molecular weight of the sample as 295,000 by detecting the intrinsic viscosity. Then continue to heat up to 65 - 75 °C and maintain for 12 - 24 h.

[0065] S4. When the molecular weight reaches 398,000, add 0.25 kg of sodium metabisulfite to terminate the polymerization reaction, and cool to ambient temperature to obtain a colloidal polyallylammonium chloride polymer.

[0066] S5. Add 288 kg of deionized water to the colloidal polymer obtained in step S4 to prepare a 15% aqueous solution of polyallylammonium chloride. Add 16.9 kg of isothiazolinone (mass fraction 14%) and 3.4 kg of sodium carboxymethylcellulose, and adjust the pH to 6.6 with AlCl3 to obtain a colorless and transparent liquid high-efficiency flocculant, namely the fouling treatment agent.

[0067] When using the fouling treatment agent prepared in this embodiment for ultrafiltration membrane fouling treatment:

[0068] Take 20 L of the sewage before the ultrafiltration membrane, with a turbidity of 2.9 NTU. Add 0.2 g of the fouling treatment agent prepared in this embodiment, approximately 10 mg / L. After 30 s of dosing and flocculation, and then after sand rate treatment, the turbidity is 0.9 NTU. The water passing volume of the filter membrane measured by the SDI device is increased from 500 mL before treatment to 3700 mL.

[0069] Example 4:

[0070] S1. Place 106.4 kg of monomer tetraallylammonium chloride in a reactor, add water to prepare an aqueous solution with a mass fraction of 75%, and introduce nitrogen for protection. The content of the impurity allylammonium chloride hydrochloride is less than 497 mg / kg, the residual Cu ion is 1.95 mg / kg, and the residual Fe ion is 1.89 mg / kg.

[0071] S2. At ambient temperature, add 1.6 kg of azobisamidinopropane hydrochloride, which accounts for 1.6 kg of the monomer mass fraction, to the aqueous solution of tetraallylammonium chloride to form a reaction solution.

[0072] S3. Add 1.06 kg of PEO to the reaction system obtained in step S2, slowly heat it with stirring, control the reaction temperature at 40 - 55 °C, react for 8 - 12 h. By detecting the intrinsic viscosity, the average molecular weight of the sample is obtained as 299,000. Continue to raise the temperature to 65 - 75 °C and maintain it for 12 - 24 h.

[0073] S4. When the molecular weight reaches 401,000, add 0.53 kg of sodium sulfite to terminate the polymerization reaction, and cool it to ambient temperature to obtain a colloidal poly(tetraallylammonium chloride) polymer.

[0074] S5. Add 954 kg of deionized water to the colloidal polymer obtained in step S4 to prepare a 10% aqueous solution of poly(tetraallylammonium chloride). Add 53 kg of Kathon (mass fraction 14%) and 3.4 kg of sodium gluconate, and adjust the pH to 6.5 with AlCl3 to obtain a colorless and transparent liquid high - efficiency flocculant, that is, the fouling treatment agent.

[0075] When using the fouling treatment agent prepared in this embodiment for ultrafiltration membrane fouling treatment:

[0076] Take 20 L of the sewage before ultrafiltration, with a turbidity of 1.8 NTU. Add 0.06 g of the high - efficiency flocculant prepared in this embodiment, approximately 3 mg / L. After 10 s of dosing and flocculation stirring, and then after sand rate treatment, the turbidity is 0.82 NTU. The water passing volume of the filter membrane measured by the SDI device is increased from 800 mL before treatment to 6200 mL.

[0077] Example 5:

[0078] S1. Place 95.4 kg of monomer tetraallylammonium chloride in a reactor, add water to prepare an aqueous solution with a mass fraction of 73%, and introduce nitrogen for protection. The content of the impurity allylammonium chloride hydrochloride is less than 450 mg / kg, the residual Cu ion is 1.7 mg / kg, and the residual Fe ion is 1.5 mg / kg.

[0079] S2. At ambient temperature, add 0.95 kg of butyllithium, accounting for the mass fraction of the monomer, to the aqueous solution of tetraallylammonium chloride to form a reaction solution.

[0080] S3. Add 1.97 kg of PEO to the reaction system obtained in step S2, slowly heat with stirring, control the reaction temperature at 40 - 55 °C, react for 8 - 12 h, and obtain the average molecular weight of the sample as 293,000 by detecting the intrinsic viscosity. Then continue to raise the temperature to 65 - 75 °C and maintain it for 12 - 24 h.

[0081] S4. When the molecular weight reaches 397,000, add 1.97 kg of sodium sulfite to terminate the polymerization reaction, and cool to ambient temperature to obtain a colloidal poly(tetraallylammonium chloride) polymer with a mass fraction of about 40.1%.

[0082] S5. Add 3080 kg of deionized water to the colloidal polymer obtained in step S4 to prepare an aqueous solution of poly(tetraallylammonium chloride) with a concentration of about 3%. Add 6.2 kg (mass fraction 14%) of isothiazolinone and 62 kg of EDTA, and adjust the pH to 6.8 with AlCl3 to obtain a colorless and transparent liquid high - efficiency flocculant, that is, the fouling treatment agent.

[0083] When using the fouling treatment agent prepared in this example for ultrafiltration membrane fouling treatment:

[0084] Take 20 L of sewage before ultrafiltration with a turbidity of 4.15 NTU, add 0.3 g of the fouling treatment agent prepared in this example, about 15 mg / L. After adding the medicine and flocculating and stirring for 15 s and then passing through sand rate treatment, the turbidity is 0.89 NTU. The water passing volume of the filter membrane measured by the SDI device is increased from 400 mL before treatment to 3200 mL.

[0085] The above is only the preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in related fields. And the changes and alterations made by those skilled in the art that do not depart from the spirit and scope of the present invention should all be within the protection scope of the appended claims of the present invention.

Claims

1. A preparation method of a fouling treatment agent, characterized in that: It includes the following steps: S1. Place monomer tetraallylammonium chloride in a reaction kettle, add water to prepare an aqueous solution of tetraallylammonium chloride with a mass fraction of 60 - 75%; S2. Add an initiator accounting for 0.01 - 1% of the monomer mass fraction to the aqueous solution of tetraallylammonium chloride obtained in step S1 to form a reaction solution; S3. Stir and heat up the reaction solution obtained in step S2 to initiate a free radical polymerization reaction; S4. Add a reducing agent to terminate the polymerization reaction, cool to room temperature to obtain a colloidal poly(tetraallylammonium chloride) polymer; S5. Dilute the colloidal poly(tetraallylammonium chloride) polymer obtained in step S4 with water to prepare an aqueous solution of poly(tetraallylammonium chloride), add a bactericide and a chelating agent, and adjust the pH to 6 - 7 with AlCl3 to obtain a liquid flocculant; the liquid flocculant is the fouling treatment agent.

2. The preparation method of a fouling treatment agent according to claim 1, characterized in that: In step S2, the initiator is one or more of tert-butyl hydroperoxide, butyllithium, persulfate, and azo organic compounds; the addition amount of the initiator is 0.05 - 1.5% of the mass of monomer tetraallylammonium chloride.

3. A method for preparing a fouling treatment agent according to claim 1, wherein: In step S2, a dispersant is also added; the dispersant is polyethylene oxide PEO; the addition amount of the dispersant is 1 - 5% of the mass of monomer tetraallylammonium chloride.

4. A preparation method of a fouling treatment agent according to claim 1, characterized in that: The temperature increase in step S3 is a stepwise temperature increase, specifically: S201. Stir the reaction solution and slowly heat up until the temperature reaches 40°C; S202. Keep the reaction temperature at 40 - 55°C, and the heat preservation time is 8 - 12 h; S203. Continue to heat up to 65 - 75°C, maintain this temperature for 12 - 24 h, and the molecular weight reaches 400,000.

5. A method for preparing a fouling treatment agent according to claim 1, characterized in that: In step S4, the reducing agent is sodium metabisulfite, sulfite, or bisulfite; the addition amount of the reducing agent is 0.5 - 3% of the mass of monomer tetraallylammonium chloride.

6. The preparation method of a fouling treatment agent according to claim 1, characterized in that: In step S5, the proportion of poly(tetraallylammonium chloride) in the liquid flocculant is 1 - 20%.

7. A method for preparing a fouling treatment agent according to claim 1, characterized in that: In step S5, the bactericide is azoxystrobin or isothiazolinone; the proportion of the bactericide in the liquid flocculant is 0.1 - 10%; the chelating agent is one or a mixture of EDTA, EDTA2Na, EDTA4Na, sodium gluconate, and sodium carboxymethylcellulose; the proportion of the chelating agent in the liquid flocculant is 0.5 - 15%.

8. A method for preparing a fouling treatment agent according to claim 1, characterized in that: In step S5, when obtaining the liquid flocculant, ultrasonic dispersion is used to ensure the homogenization of components.

9. A fouling treatment agent, characterized in that: It is prepared by using the fouling treatment agent preparation method described in any one of claims 1 - 8.

10. A method for treating ultrafiltration membrane fouling, characterized in that: Based on the fouling treatment agent described in claim 9, add the fouling treatment agent to the sewage before the ultrafiltration membrane, let it react for 10 - 30 s, and then perform sand filtration treatment on the sewage.

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