A composite membrane for wastewater treatment and preparation method thereof

Abstract

The present application relates to the technical field of wastewater treatment, and specifically discloses a composite membrane for wastewater treatment and a preparation method thereof. The preparation method of the composite membrane for wastewater treatment provided in the present application comprises the following steps in sequence: preparation of base membrane: respectively dissolving piperazine, m-phenylenediamine, and castor oil polyoxyethylene ether in water, adding auxiliary agents and ammonia water, and uniformly mixing at room temperature to obtain an aqueous phase solution, and filtering the aqueous phase solution to the surface of a polyacrylonitrile microfiltration membrane, and drying to obtain a base membrane; the auxiliary agent is composed of a mixture of isononyl alcohol, trisodium citrate dihydrate, and propylene glycol alginate; preparation of composite membrane: soaking the base membrane in an oil phase solution under light-proof conditions, taking it out, and rinsing it with water to obtain a composite membrane for wastewater treatment; the oil phase solution comprises an oil phase monomer and an organic solvent; the organic solvent is composed of a mixture of saturated alkanes and toluene in a weight ratio of 3-7:1. The composite membrane for wastewater treatment provided in the present application has good water flux and desalination rate as well as excellent acid and alkali resistance.

Description

Technical Field

[0001] The present application relates to the technical field of wastewater treatment, and in particular to a composite membrane for wastewater treatment and a preparation method thereof. Background Art

[0002] In recent years, with the increasing demand for water in the world, water resource depletion and water quality deterioration have become serious problems. Zero discharge of industrial wastewater is one of the important ways to solve my country's water resource problems, and its application in power plant wastewater, coal chemical wastewater and other fields is increasing.

[0003] At present, membrane technology has attracted wide attention from various industries due to its advantages such as cleanliness, no pollution, and no phase change. Wastewater separation membrane is a liquid separation technology widely used in seawater desalination, brackish water desalination, ultrapure water manufacturing, food and medical fields, and its importance is becoming increasingly significant. However, with the continuous expansion of the application market, the performance requirements for water separation and treatment membrane products are constantly increasing; not only must it have high desalination rate and high water production, but also good acid and alkali resistance.

[0004] Therefore, there is an urgent need to develop a wastewater treatment composite membrane with excellent acid and alkali resistance. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a wastewater treatment composite membrane and a preparation method thereof.

[0006] The present application provides a method for preparing a composite membrane for wastewater treatment, which specifically comprises the following steps in sequence:

[0007] Preparation of base film: according to weight parts, 5-8 parts of piperazine, 0.2-0.5 parts of m-phenylenediamine, and 0.05-0.15 parts of castor oil polyoxyethylene ether are weighed and dissolved in 80-90 parts of water, and then 0.08-0.16 parts of auxiliary agent and 0.01-0.05 parts of ammonia water are added, and mixed evenly at room temperature to obtain an aqueous phase solution, and the aqueous phase solution is filtered onto the surface of a polyacrylonitrile microfiltration membrane, and dried to obtain a base film; the auxiliary agent is composed of a mixture of isononanol, trisodium citrate dihydrate, and propylene glycol alginate in a weight ratio of 10:0.6-1.2:0.6-1.2;

[0008] Preparation of composite membrane: Under light-proof conditions, immerse the base membrane in an oil phase solution, soak it at a soaking temperature of 30-40° C. for 3-6 hours, and then soak it at a soaking temperature of 70-80° C. for 10-20 minutes; after taking it out, rinse it with 30-40° C. water to obtain the wastewater treatment composite membrane;

[0009] The oil phase solution comprises the following raw materials in parts by weight: 0.2-0.4 parts of oil phase monomer and 95-100 parts of organic solvent; the organic solvent is a mixture of saturated alkane and toluene in a weight ratio of 3-7:1.

[0010] The present application adopts the above-mentioned technical scheme. During the preparation process of the base membrane, by adding appropriate types and amounts of castor oil polyoxyethylene ether and additives, when the water phase diffuses into the oil phase and a polymerization reaction occurs at the interface, piperazine preferentially participates in the cross-linking reaction. As the reaction proceeds, m-phenylenediamine further participates in the cross-linking reaction, thereby increasing the overall cross-linking degree of the wastewater treatment composite membrane, so that the composite membrane obtains a better retention rate and water flux; but at the same time, as the cross-linking degree of the composite membrane is improved, the hydrophilic residues on the surface of the composite membrane will also be reduced accordingly, thereby reducing the hydrophilicity of the composite membrane and the water flux. Therefore, it is necessary to reasonably control the amount of each raw material within the range permitted by the technical scheme of the present application.

[0011] During the experiment, the inventors found that in the process of immersing the base membrane into the oil phase solution to prepare the composite membrane, it is necessary to reasonably control the immersion temperature and immersion time. The present application obtained a composite membrane with excellent performance by first immersing it at a immersion temperature of 30-40°C for 3-6h, and then immersing it at a immersion temperature of 70-80°C for 10-20min. The occurrence of this reaction process can change the chemical bonding strength, and can also increase the distance between molecular cross-links, thereby increasing the free volume in the composite membrane and reducing the density, thereby achieving the effect of increasing the water flux.

[0012] In addition, in order to further improve the acid and alkali durability of the composite membrane, in the process of selecting the raw material components of the oil phase solution, the present application selects a mixture of saturated alkanes and toluene in a weight ratio of 3-7:1 to form an organic solvent.

[0013] Preferably, the amount of castor oil polyoxyethylene ether is 0.08-0.12 g.

[0014] Preferably, the saponification value of the castor oil polyoxyethylene ether is 90-100 mgKOH / g.

[0015] Through experimental analysis, it can be known that the present application selects the castor oil polyoxyethylene ether of the above dosage and specification, which further enhances the performance of the wastewater treatment composite membrane, making the composite membrane have the characteristics of strong capture force, and has higher flux and retention rate.

[0016] Preferably, in the auxiliary agent, the amount of trisodium citrate dihydrate is not less than the amount of propylene glycol alginate.

[0017] Preferably, the auxiliary agent is composed of a mixture of isononanol, trisodium citrate dihydrate and propylene glycol alginate in a weight ratio of 10:0.9-1.2:0.6-0.9.

[0018] Preferably, the oil phase monomer is selected from one or more of 1,3,5-benzenetricarboxylic acid chloride, 1,3-benzenediol chloride, bridged bicyclic tricyclic tetracarboxylic acid chloride, and biphenylhexacarboxylic acid chloride.

[0019] Preferably, the organic solvent is a saturated alkane and toluene in a weight ratio of 4-6:1.

[0020] Preferably, the organic solvent is a saturated alkane and toluene in a weight ratio of 5:1.

[0021] Through experimental analysis, it can be known that the present application selects a mixture of saturated alkanes and toluene in the above weight ratio to form an organic solvent, which can further improve the performance of the composite membrane.

[0022] Preferably, the saturated alkane is selected from one or more of n-heptane, n-hexane and petroleum ether.

[0023] On the other hand, the present application provides a composite membrane for wastewater treatment, which is prepared by the above-mentioned preparation method.

[0024] In summary, the technical solution of this application has the following effects:

[0025] In the technical solution provided in the present application, by adding appropriate types and amounts of castor oil polyoxyethylene ether and additives to the base membrane, and in the process of immersing the base membrane in an oil phase solution to prepare a composite membrane, the raw materials and immersion conditions are reasonably controlled, thereby obtaining a wastewater treatment composite membrane with good water flux and desalination rate and relatively excellent acid and alkali resistance. DETAILED DESCRIPTION

[0026] The present application is further described in detail below in conjunction with examples, comparative examples and performance testing experiments. These examples should not be construed as limiting the scope of protection claimed in the present application. Example Example 1

[0027] Example 1 provides a composite membrane for wastewater treatment.

[0028] The specific steps of the preparation method of the composite membrane for wastewater treatment in this embodiment are as follows:

[0029] Preparation of base film: according to weight parts, 6g piperazine, 0.3g m-phenylenediamine, and 0.1g castor oil polyoxyethylene ether with a saponification value of 90-100mgKOH / g (specification EL-20, purchased from Hai'an Petrochemical Plant, Jiangsu Province) were weighed and dissolved in 85g water, and then 0.12g auxiliary agent and 0.02g ammonia water were added and mixed evenly to obtain an aqueous phase solution, and the aqueous phase solution was filtered onto the surface of a polyacrylonitrile microfiltration membrane with a pore size of 0.05μm, and dried to obtain a base film; the auxiliary agent is composed of a mixture of isononanol, trisodium citrate dihydrate, and propylene glycol alginate in a weight ratio of 10:1.2:0.6;

[0030] Preparation of composite membrane: Under light-proof conditions, immerse the base membrane in the oil phase solution, immerse it at a immersion temperature of 35°C for 4 hours, and then immerse it at a immersion temperature of 75°C for 15 minutes; after taking it out, rinse it with 35°C water to obtain a wastewater treatment composite membrane; the oil phase solution includes the following raw materials in parts by weight: 0.3g 1,3-phthaloyl chloride oil phase monomer and 100g organic solvent (the organic solvent is composed of a mixture of n-hexane and toluene in a weight ratio of 5:1).

[0031] Embodiment 2-5

[0032] Examples 2-5 each provide a composite membrane for wastewater treatment.

[0033] The difference between the above embodiment and embodiment 1 is that the type and amount of castor oil polyoxyethylene ether are different, as shown below.

[0034] In Example 2: the specification of castor oil polyoxyethylene ether is EL-12, and the saponification value is 110-120 mgKOH / g.

[0035] In Example 3: the specification of castor oil polyoxyethylene ether is EL-40, and the saponification value is 57-67 mgKOH / g.

[0036] In Example 4, the amount of castor oil polyoxyethylene ether having a saponification value of 90-100 mgKOH / g is 0.05 g.

[0037] In Example 5, the amount of castor oil polyoxyethylene ether having a saponification value of 90-100 mgKOH / g is 0.15 g.

[0038] The remaining raw material components of the composite membrane for wastewater treatment, the amounts of the raw material components, and the preparation method of the composite membrane for wastewater treatment in the above embodiment are the same as those in Example 1.

[0039] Embodiment 6-9

[0040] Examples 6-9 each provide a composite membrane for wastewater treatment.

[0041] The difference between the above embodiment and embodiment 1 is that the composition of the auxiliary agent is different, as shown below.

[0042] In Example 6: the auxiliary agent is composed of a mixture of isononanol, trisodium citrate dihydrate and propylene glycol alginate in a weight ratio of 10:1.2:0.9.

[0043] In Example 7: the auxiliary agent is composed of a mixture of isononyl alcohol, trisodium citrate dihydrate and propylene glycol alginate in a weight ratio of 10:0.9:0.9.

[0044] In Example 8: the auxiliary agent is composed of a mixture of isononyl alcohol, trisodium citrate dihydrate and propylene glycol alginate in a weight ratio of 10:0.6:0.9.

[0045] In Example 9: the auxiliary agent is composed of a mixture of isononanol, trisodium citrate dihydrate and propylene glycol alginate in a weight ratio of 10:0.6:1.2.

[0046] The remaining raw material components of the composite membrane for wastewater treatment, the amounts of the raw material components, and the preparation method of the composite membrane for wastewater treatment in the above embodiment are the same as those in Example 1.

[0047] Examples 10-15

[0048] Examples 10-15 each provide a composite membrane for wastewater treatment.

[0049] The difference between the above embodiment and embodiment 1 is that the types of oil phase monomer and organic solvent are different, as shown below.

[0050] In Example 10: the oil phase monomer is 1,3,5-benzenetricarboxylic acid chloride.

[0051] In Example 11: the oil phase monomer is biphenylhexacarbonyl chloride.

[0052] In Example 12: the organic solvent is composed of a mixture of n-heptane and toluene in a weight ratio of 5:1.

[0053] In Example 13: the organic solvent is composed of a mixture of petroleum ether and toluene in a weight ratio of 5:1.

[0054] In Example 14: the organic solvent is composed of a mixture of n-hexane and toluene in a weight ratio of 3:1.

[0055] In Example 15: the organic solvent is composed of a mixture of n-hexane and toluene in a weight ratio of 7:1.

[0056] The remaining raw material components of the composite membrane for wastewater treatment, the amounts of the raw material components, and the preparation method of the composite membrane for wastewater treatment in the above embodiment are the same as those in Example 1. Comparative Example

[0057] Comparative Examples 1-5

[0058] Comparative Examples 1-5 provide a composite membrane for wastewater treatment.

[0059] The differences between the wastewater treatment composite membranes in Comparative Examples 1-5 and Example 1 are as follows.

[0060] In Comparative Example 1: During the preparation of the base film, castor oil polyoxyethylene ether was not added.

[0061] In Comparative Example 2: During the preparation of the base film, the auxiliary agent is composed of a mixture of isononanol and trisodium citrate dihydrate in a weight ratio of 10:1.8.

[0062] In Comparative Example 3: During the preparation of the base film, the auxiliary agent is composed of a mixture of isononanol, trisodium citrate dihydrate, and propylene glycol alginate in a weight ratio of 10:1.5:0.4.

[0063] In Comparative Example 4: During the preparation of the composite membrane, the organic solvent was n-hexane.

[0064] In Comparative Example 5: During the preparation of the composite membrane, the organic solvent is toluene.

[0065] The remaining raw material components of the composite membrane for wastewater treatment, the amounts of the raw material components, and the preparation method of the composite membrane for wastewater treatment in this comparative example and Example 2 are the same. Comparative Example 6

[0066] Comparative Example 6 provides a composite membrane for wastewater treatment.

[0067] The specific steps of the preparation method of the composite membrane for wastewater treatment in this comparative example are as follows:

[0068] Preparation of base film: according to weight, 6g piperazine, 0.3g m-phenylenediamine, and 0.1g castor oil polyoxyethylene ether (specification EL-20) with a saponification value of 90-100mgKOH / g are weighed and dissolved in 85g water, and then 0.12g auxiliary agent and 0.02g ammonia water are added and mixed evenly to obtain an aqueous phase solution, and the aqueous phase solution is filtered onto the surface of a polyacrylonitrile microfiltration membrane with a pore size of 0.05μm, and dried to obtain a base film; the auxiliary agent is composed of a mixture of isononanol, trisodium citrate dihydrate, and propylene glycol alginate in a weight ratio of 10:1.2:0.6;

[0069] Preparation of composite membrane: Under light-proof conditions, immerse the base membrane in the oil phase solution, and then immerse it at a soaking temperature of 75°C for 50 minutes; after taking it out, rinse it with 35°C water to obtain a wastewater treatment composite membrane; the oil phase solution includes the following raw materials in parts by weight: 0.3g 1,3-phthaloyl chloride oil phase monomer and 100g organic solvent (the organic solvent is composed of a mixture of n-hexane and toluene in a weight ratio of 5:1). Comparative Example 7

[0070] Comparative Example 7 provides a composite membrane for wastewater treatment.

[0071] The specific steps of the preparation method of the composite membrane for wastewater treatment in this comparative example are as follows:

[0072] Preparation of base film: according to weight, 6g piperazine, 0.3g m-phenylenediamine, and 0.1g castor oil polyoxyethylene ether (specification EL-20) with a saponification value of 90-100mgKOH / g are weighed and dissolved in 85g water, and then 0.12g auxiliary agent and 0.02g ammonia water are added and mixed evenly to obtain an aqueous phase solution, and the aqueous phase solution is filtered onto the surface of a polyacrylonitrile microfiltration membrane with a pore size of 0.05μm, and dried to obtain a base film; the auxiliary agent is composed of a mixture of isononanol, trisodium citrate dihydrate, and propylene glycol alginate in a weight ratio of 10:1.2:0.6;

[0073] Preparation of composite membrane: without shielding from light, immerse the base membrane in the oil phase solution and soak it at a soaking temperature of 35°C for 4 hours; after taking it out, rinse it with water at 35°C to obtain a wastewater treatment composite membrane; the oil phase solution includes the following raw materials in parts by weight: 0.3g of 1,3-phthaloyl chloride oil phase monomer and 100g of organic solvent (the organic solvent is composed of a mixture of n-hexane and toluene in a weight ratio of 5:1).

[0074] Performance testing

[0075] Retention rate and water flux performance test: 1000ppm sodium chloride solution and 3000ppm magnesium sulfate solution were prepared as test solutions. The pH value of the two test solutions was adjusted to 7.5. The prepared wastewater treatment composite membrane was installed in the test pool of the membrane performance evaluation instrument. The test pressure was 1.6MPa and the test temperature was 25°C. Rinse with pure water for 30 minutes, pre-press for 30 minutes before starting the test. Then collect the produced water from each test pool within a certain period of time, record the test time, and calculate the retention rate and water flux of the wastewater treatment composite membrane. Water flux = produced water volume / (effective membrane area×test time), unit is L / (m 2 h); Retention rate = (1-influent conductivity / product conductivity) × 100%.

[0076] Acid-base durability test: (1) Alkali durability test: Alkaline washing conditions: NaOH (pH=13.0) + 0.025% Na-SDS solution, soaking overnight for 16 hours, temperature is 25-30℃, and then the membrane retention rate and water flux of 1000ppm sodium chloride solution are tested; (2) Acid durability test: Acid washing conditions: HCl (pH=1.0) solution, soaking for 2 hours, temperature is 25-30℃, and then the membrane retention rate and water flux of 1000ppm sodium chloride solution are tested.

[0077] Test results: as shown in Table 1.

[0078] Table 1 Performance of composite membranes for wastewater treatment in Examples 1-15 and Comparative Examples 1-7

[0079]

[0080] Combined with Table 1, by comparing the test results of Examples 1-15 with those of Comparative Examples 1-7, the present application adds castor oil polyoxyethylene ether of appropriate type and amount to the base membrane, and at the same time mixes isononanol, trisodium citrate dihydrate, and propylene glycol alginate to form an auxiliary agent; and in the process of immersing the base membrane in the oil phase solution to prepare the composite membrane, the raw materials and immersion conditions are reasonably controlled, and a wastewater treatment composite membrane with good water flux and desalination rate and excellent acid and alkali resistance is obtained.

[0081] By comparing the test results of Examples 1-5 with Comparative Example 1, in the process of preparing the base film, compared with not adding castor oil polyoxyethylene ether, the present application adds an appropriate amount of castor oil polyoxyethylene ether, which can significantly improve the interception rate of the composite membrane for the salt solution, and the acid-base durability is higher. Further, the present application selects castor oil polyoxyethylene ether with an amount of 0.08-0.12 parts by weight and a saponification value of 90-100 mgKOH / g as a raw material.

[0082] By comparing the test results of Examples 1, 6-9 with Comparative Examples 2-3, in the process of preparing the base membrane, the present application selects a mixture of isononanol, trisodium citrate dihydrate, and propylene glycol alginate in a weight ratio of 10:0.6-1.2:0.6-1.2 to form an auxiliary agent, which can effectively improve the hydrophilicity of the composite membrane and the retention rate of the salt solution.

[0083] By comparing the test results of Example 1 with those of Comparative Examples 6-7, it is found that in the process of immersing the base film into the oil phase solution to prepare the composite film, it is necessary to reasonably control the immersion temperature and immersion time; the present application first soaks it at a soaking temperature of 30-40°C for 3-6h, and then soaks it at a soaking temperature of 70-80°C for 10-20min, thereby obtaining a composite film with excellent performance.

[0084] By comparing the test results of Examples 1, 12-15 with Comparative Examples 4-5, in the process of selecting the raw material components of the oil phase solution, the present application uses a mixture of saturated alkanes and toluene in a weight ratio of 3-7:1 to form an organic solvent, which can significantly improve the acid-base durability of the composite membrane.

[0085] By comparing the test results of Examples 2 and 10-11, compared with selecting 1,3,5-benzenetricarboxylic acid chloride or biphenylhexacarboxylic acid chloride as the oil phase monomer, the present application selects 1,3-benzenedioyl chloride as the oil phase monomer, which can further improve the performance of the composite membrane.

[0086] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a composite membrane for wastewater treatment, characterized in that: Specifically, the following steps are performed in sequence: Preparation of base film: according to weight parts, 5-8 parts of piperazine, 0.2-0.5 parts of m-phenylenediamine, and 0.05-0.15 parts of castor oil polyoxyethylene ether are weighed and dissolved in 80-90 parts of water, and then 0.08-0.16 parts of auxiliary agent and 0.01-0.05 parts of ammonia water are added, and mixed evenly at room temperature to obtain an aqueous phase solution, and the aqueous phase solution is filtered onto the surface of a microfiltration membrane, and dried to obtain a base film; The auxiliary agent is composed of a weight ratio of 10: 0.6-1.2: 0.6-1.2 of isononyl alcohol, trisodium citrate dihydrate, and propylene glycol alginate; Preparation of composite membrane: Under light-proof conditions, immerse the base membrane in an oil phase solution, soak it at a soaking temperature of 30-40° C. for 3-6 hours, and then soak it at a soaking temperature of 70-80° C. for 10-20 minutes; after taking it out, rinse it with 30-40° C. water to obtain the wastewater treatment composite membrane; The oil phase solution comprises the following raw materials in parts by weight: 0.2-0.4 parts of oil phase monomer and 95-100 parts of organic solvent; the organic solvent is a mixture of saturated alkane and toluene in a weight ratio of 3-7:

1.

2. The method for preparing a composite membrane for wastewater treatment according to claim 1, characterized in that: The usage of the castor oil polyoxyethylene ether is 0.08-0.12 parts by weight.

3. The method for preparing a composite membrane for wastewater treatment according to claim 1, characterized in that: The saponification value of the castor oil polyoxyethylene ether is 90-100 mgKOH / g.

4. The method for preparing a composite membrane for wastewater treatment according to claim 1, characterized in that: In the auxiliary agent, the amount of trisodium citrate dihydrate is not less than the amount of propylene glycol alginate.

5. The method for preparing a composite membrane for wastewater treatment according to claim 4, characterized in that: The auxiliary agent is composed of a weight ratio of 10: 0.9-1.2:0.6-0.9 of isononyl alcohol, trisodium citrate dihydrate and propylene glycol alginate are mixed.

6. The method for preparing a composite membrane for wastewater treatment according to claim 1, characterized in that: The oil phase monomer is selected from one or more of 1,3,5-benzenetricarboxylic acid chloride, 1,3-benzenediol chloride, bridged bicyclic tricyclic tetracarboxylic acid chloride, and biphenylhexacarboxylic acid chloride.

7. The method for preparing a composite membrane for wastewater treatment according to claim 1, characterized in that: The organic solvent is a saturated alkane and toluene in a weight ratio of 4-6:

1.

8. The method for preparing a composite membrane for wastewater treatment according to claim 7, characterized in that: The organic solvent is saturated alkane and toluene in a weight ratio of 5:

1.

9. The method for preparing a composite membrane for wastewater treatment according to claim 7, characterized in that: The saturated alkane is selected from one or more of n-heptane, n-hexane and petroleum ether.

10. A composite membrane for wastewater treatment, characterized in that: The wastewater treatment composite membrane is prepared by the preparation method described in any one of claims 1-9.

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