Conductive deamination composite membrane for treating oil-containing high-ammonia-nitrogen wastewater as well as preparation method and application of conductive deamination composite membrane

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a conductive deamination composite membrane for treating oil-containing high-ammonia-nitrogen wastewater as well as a preparation method and application of the conductive deamination composite membrane. The conductive deamination composite film provided by the invention comprises a conductive film and a deamination film, a stainless steel net film is immersed in a mixed solution containing an aluminum source and an acid catalyst, drying is performed after stirring reaction, an aluminum oxide insulating layer is formed on the surface of the stainless steel net film, then the stainless steel net film is immersed in a silane coupling agent solution, and curing treatment is performed to obtain the conductive film. And finally, compounding with a deamination membrane. The deamination composite membrane with excellent performance is obtained by optimizing the structure, surface characteristics and preparation process parameters of the conducting layer, and the technical effects of efficiently treating high-ammonia-nitrogen oil-containing wastewater, reducing energy consumption and relieving membrane pollution are achieved by applying the deamination composite membrane to high-ammonia-nitrogen oil-containing wastewater treatment. The problems of low treatment efficiency, high energy consumption and serious membrane pollution in the prior art are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and more specifically relates to a conductive deammoniation composite membrane for treating oil-containing high-ammonia-nitrogen wastewater, its preparation method and application. Background Art

[0002] High-ammonia-nitrogen oil-containing wastewater is a type of complex industrial wastewater generated during the production processes of industries such as petrochemical and coal chemical industries. How to treat high-ammonia-nitrogen oil-containing wastewater to reduce pollution while fully recovering valuable substances such as ammonia nitrogen has become an important research and development direction in the field of industrial wastewater treatment.

[0003] Existing high-ammonia-nitrogen oil-containing wastewater treatment technologies mainly include: traditional biological treatment methods, membrane separation technologies, chemical precipitation methods, oxidation methods, etc. However, these technologies often face problems such as low treatment efficiency, high energy consumption, and serious membrane fouling in actual applications, and do not fundamentally solve the problems of efficient treatment and resource utilization of high-ammonia-nitrogen oil-containing wastewater, restricting their large-scale industrial applications.

[0004] The main reasons for these problems include: on the one hand, when traditional membrane separation technologies are used to treat such wastewater, the membrane surface is easily attached with oils and organic pollutants, resulting in a rapid decline in membrane flux and requiring frequent cleaning, increasing the operating cost and maintenance difficulty; on the other hand, existing membrane materials and processes have limitations in reducing energy consumption and improving ammonia nitrogen selective separation, and it is difficult to balance efficient deammoniation effects and economy.

[0005] Based on the problems and defects of the above existing technologies, the technical problem to be solved by the present invention is how to provide a new composite membrane capable of efficiently treating high-ammonia-nitrogen oil-containing wastewater, reducing energy consumption, alleviating membrane fouling and realizing resource recovery of ammonia nitrogen, as well as its preparation method and application. Summary of the Invention

[0006] The purpose of the present invention is to provide a conductive deammoniation composite membrane for treating oil-containing high-ammonia-nitrogen wastewater, its preparation method and application to solve the problems existing in the above existing technologies.

[0007] To achieve the above purpose, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention: provides a conductive deammoniation composite membrane for treating oil-containing high-ammonia-nitrogen wastewater, including a conductive membrane and a deamination membrane;

[0009] The conductive membrane includes a stainless steel mesh substrate, an alumina insulating middle layer and a hydrophilic outer layer;

[0010] The deamination membrane includes at least one of polytetrafluoroethylene membrane (PTFE), polypropylene membrane (PP) and polyvinylidene fluoride membrane (PVDF).

[0011] The second technical solution of the present invention: Provide a preparation method of the above-mentioned conductive deammoniation composite membrane for treating oily high-ammonia-nitrogen wastewater, and the steps include:

[0012] Immerse the stainless steel mesh in a mixed solution containing an aluminum source and an acidic catalyst, stir and react, then dry to form an alumina insulating layer on the surface of the stainless steel mesh, and then immerse it in a silane coupling agent solution and perform a curing treatment to obtain a conductive membrane;

[0013] Composite the conductive membrane with a deaminated membrane to obtain the conductive deammoniation composite membrane for treating oily high-ammonia-nitrogen wastewater.

[0014] In the present invention, an alumina insulating layer and a hydrophilic coating are formed on the surface of the stainless steel mesh. Among them, the double amino groups (-NH2 / -NH-), hydrolyzed silanol groups (-Si-OH), mercapto groups (-SH), epoxy groups (-CHOCH-), vinyl groups (-CH=CH2) and ureido groups (-NH2CONH) in the molecules of the silane coupling agent form a dense polar layer on the membrane surface, reducing the contact angle, significantly improving the hydrophilicity, and the surface energy and hydrophilic-hydrophobic polarity difference with oil pollutants. Combining with the physical barrier effect of the hydration layer, the adhesion is reduced, thereby enhancing the anti-pollution performance of the membrane; the hydrophilic surface compresses the thickness of the gas film diffusion layer, shortening the transmembrane path of ammonia, and by regulating and strengthening the local NH3 concentration gradient, the transmission efficiency of ammonia nitrogen is improved.

[0015] Further, the pore size range of the stainless steel mesh is 10-40 μm.

[0016] Further, the solvent in the mixed solution is ethanol, the concentration of the aluminum source is 0.2-0.4 mol / L, and the dosage of the acidic catalyst is 2-5% of the amount of substance of the aluminum source.

[0017] The purpose of selecting ethanol as the solvent is to ensure that the dissolution process of the aluminum source is not interfered by moisture. When immersing the stainless steel mesh in the mixed solution, ensure that the stainless steel mesh is completely immersed to avoid the situation of residual air in the membrane pores.

[0018] Further, the aluminum source includes at least one of aluminum isopropoxide, aluminum isobutoxide and sodium metaaluminate.

[0019] Further, the acidic catalyst includes at least one of acetic acid, formic acid, propionic acid and butyric acid.

[0020] Further, the temperature of the stirring reaction is 60-80 °C, and the time is 4-6 h.

[0021] The purpose of the stirring reaction is to ensure that the alumina insulating layer can be formed uniformly and stably. During the stirring reaction, the membrane pores can be prevented from being blocked by gently shaking.

[0022] Further, the drying temperature is 80 - 90 °C.

[0023] Drying at a defined temperature can promote the curing of the alumina insulating layer.

[0024] Further, the solvent in the silane coupling agent solution is ethanol and water, and the concentration of the silane coupling agent is 0.5 - 2 wt.%.

[0025] Optionally, the volume ratio of ethanol to water in the solvent is 1:9 - 5:5.

[0026] Further, the silane coupling agent in the silane coupling agent solution includes at least one of KH550, KH560, KH570, KH580, KH590, KH602, KH791, and KH792.

[0027] Further, the time for immersion in the silane coupling agent solution is 10 - 30 min.

[0028] Further, the temperature of the curing treatment is 50 - 70 °C, and the time is 1 - 2 h.

[0029] The curing treatment can improve the adhesion of the coupling agent. The curing process can form a chemical bond between the coupling agent and the substrate surface, enhancing the durability and adhesion of the coating.

[0030] Further, the compounding of the conductive film and the deaminated film is to compound the conductive film and the deaminated film by physical attachment.

[0031] Further, it also includes a pretreatment step for the stainless steel mesh: ultrasonically cleaning the stainless steel mesh with anhydrous ethanol, dilute hydrochloric acid solution, and deionized water in sequence for 30 - 60 min.

[0032] The purpose of the pretreatment step for the stainless steel mesh is to remove surface oil stains and impurities.

[0033] The third technical solution of the present invention: Provide an application of the above conductive deamination composite membrane for treating high-ammonia-nitrogen wastewater containing oil in the treatment of high-ammonia-nitrogen oily wastewater.

[0034] The fourth technical solution of the present invention: Provide a membrane deamination device, including the above conductive deamination composite membrane for treating high-ammonia-nitrogen wastewater containing oil and a DC power supply unit;

[0035] The DC power supply unit applies current to the deamination membrane for treating oily ammonia-distilled wastewater.

[0036] Further, the range of the current is 1 - 10 A.

[0037] Fifth technical solution of the present invention: Provide an application of the above-mentioned membrane deammoniation device in the treatment of oily wastewater with high ammonia nitrogen content.

[0038] The present invention discloses the following technical effects:

[0039] By optimizing the structure, surface characteristics and preparation process parameters of the deammoniation composite membrane, the present invention obtains a deammoniation composite membrane with excellent performance. When it is used in the treatment of oily wastewater with high ammonia nitrogen content, it realizes the technical effects of efficiently treating oily wastewater with high ammonia nitrogen content, reducing energy consumption and alleviating membrane fouling, and solves the problems of low treatment efficiency, high energy consumption and serious membrane fouling in the prior art.

[0040] By combining the deammoniation composite membrane with electrothermal technical means, electrothermal is directly applied to the surface of the deammoniation composite membrane to reduce temperature polarization, improve the thermal utilization efficiency, promote the volatilization and mass transfer of ammonia nitrogen, and at the same time reduce the energy consumption of the system. While efficiently treating oily wastewater with high ammonia nitrogen content, the resource recovery of ammonia nitrogen is realized. Description of the Drawings

[0041] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0042] Figure 1 It is a schematic structural diagram of the device for treating oily ammonia nitrogen wastewater with the conductive deammoniation membrane in Example 1, where the reference numerals: water storage tank 1, hot water bath assembly 2, valve 3, pump 4, conductive layer 5, deammoniation membrane 6, DC power supply 7, valve 8, cold water bath assembly 9, pump 10, flowmeter 11, water production tank 12.

[0043] Figure 2 It is the ammonia nitrogen removal rate of the composite membranes in Examples 1-4 during the deammoniation process, where a is Example 1, b is Example 2, c is Example 3, and d is Example 4.

[0044] Figure 3 It is the retention rate of coal tar by the composite membranes in Examples 1-4 during the deammoniation process, where a is Example 1, b is Example 2, c is Example 3, and d is Example 4.

[0045] Figure 4 It is the ammonia nitrogen removal rate during the deammoniation process when the pH of the raw material liquid is 7 and 11.

[0046] Figure 5 It is the retention rate of coal tar during the deammoniation process when the pH of the raw material liquid is 7 and 11

[0047] Figure 6 It is the ammonia nitrogen removal rate during the deammoniation process when the temperature of the raw material liquid is 60°C and 20°C.

[0048] Figure 7 The retention rate of coal tar during the deammoniation process when the temperature of the raw material liquid is 60 °C and 20 °C.

[0049] Figure 8 The ammonia nitrogen removal rate during the deammoniation process when the concentration of the sulfuric acid solution used as the absorbent is 0 mol / L and 0.25 mol / L.

[0050] Figure 9 The retention rate of coal tar during the deammoniation process when the concentration of the sulfuric acid solution used as the absorbent is 0 mol / L and 0.25 mol / L.

[0051] Figure 10 Shows the trend of the ammonia nitrogen removal rate of the electrothermal layer changing with time under different current conditions (10 A and 0 A).

[0052] Figure 11 The retention rate (removal rate) of coal tar during the deammoniation process when the conductive film is connected to the power supply and when it is not connected.

[0053] Figure 12 SEM image of one side of the conductive layer of the composite membrane obtained in Example 5.

[0054] Figure 13 The ammonia nitrogen removal rate of the composite membranes of Example 5 and Comparative Example 1 during the deammoniation process.

[0055] Figure 14 The retention rate of coal tar of the composite membranes of Example 5 and Comparative Example 1 during the deammoniation process.

[0056] Figure 15 The ammonia nitrogen removal rate of the composite membranes of Example 1 and Comparative Example 2 during the deammoniation process.

[0057] Figure 16 The retention rate of coal tar of the composite membranes of Example 1 and Comparative Example 2 during the deammoniation process.

[0058] Figure 17 The ammonia nitrogen removal rate of the composite membranes of Example 4 and Comparative Example 3 during the deammoniation process.

[0059] Figure 18 The retention rate of coal tar of the composite membranes of Example 4 and Comparative Example 3 during the deammoniation process.

[0060] Figure 19 The ammonia nitrogen removal rate of the composite membranes of Example 2 and Comparative Example 4 during the deammoniation process.

[0061] Figure 20 The retention rate of coal tar of the composite membranes of Example 2 and Comparative Example 4 during the deammoniation process.

[0062] Figure 21Ammonia nitrogen removal rate of the composite membranes in Example 1 and Comparative Example 5 during the ammonia removal process.

[0063] Figure 22 Retention rate of coal tar by the composite membranes in Example 1 and Comparative Example 5 during the ammonia removal process.

[0064] Figure 23 Ammonia nitrogen removal rate of the composite membranes in Example 1 and Comparative Example 6 during the ammonia removal process.

[0065] Figure 24 Retention rate of coal tar by the composite membranes in Example 1 and Comparative Example 6 during the ammonia removal process.

[0066] Figure 25 Surface morphology diagrams of the SSM original membrane and KH792 - Al2O3 - SSM in Example 1.

[0067] Figure 26 Element distribution diagram of KH792 - Al2O3 - SSM in Example 1.

[0068] Figure 27 XPS diagrams of the SSM original membrane and KH792 - Al2O3 - SSM in Example 1, where (a) is the full XPS spectrum of the SSM original membrane and KH792 - Al2O3 - SSM, (b) is the high - resolution O1s spectrum, (c) is the high - resolution C1s spectrum, (d) is the high - resolution N1s spectrum, and (e) is the high - resolution Si2p spectrum.

[0069] Figure 28 SEM and EDS diagrams of KH792 - Al2O3 - SSM - 2 / PTFE in Example 3.

[0070] Figure 29 SEM diagrams of the SSM original membrane and Al2O3 - SSM / PTFE in Comparative Example 1 and the element distribution diagram of SSM - Al2O3 in Al2O3 - SSM / PTFE.

[0071] Figure 30 SEM and EDS diagrams of KH792 - Al2O3 - SSM - T2 / PTFE with an alumina insulation layer preparation reaction time of 2 h in Comparative Example 5.

[0072] Figure 31 SEM diagram of KH792 - SSM - Al2O3 - T8 / PTFE with an alumina insulation layer preparation reaction time of 8 h in Comparative Example 6.

[0073] Figure 32 Schematic diagram of the modification preparation of the conductive layer (electric heating layer) of the composite membrane and the ammonia removal and oil resistance mechanism of the composite membrane. Detailed implementation manners

[0074] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation on the present invention, but rather as a more detailed description of certain aspects, features, and implementation manners of the present invention.

[0075] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0076] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0077] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the present invention specification are obvious to those skilled in the art. The present invention specification and examples are merely exemplary.

[0078] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0079] Based on the problems existing in the prior art when treating oily wastewater containing high ammonia nitrogen, the present invention provides a composite membrane with high efficiency, low energy consumption, and anti-pollution, as well as its preparation method and application, to solve the following technical problems:

[0080] By optimizing the membrane material and structure, the present invention significantly improves the ammonia nitrogen removal rate and water flux (improving the treatment efficiency), and solves the problems of low treatment efficiency and difficulty in meeting industrial requirements in the prior art when treating oily wastewater containing high ammonia nitrogen;

[0081] Combined with electrothermal membrane technology, the present invention directly applies electrothermal on the membrane surface to reduce temperature polarization and improve the thermal utilization efficiency, thereby reducing energy consumption and solving the problem of high energy consumption in traditional membrane distillation technology;

[0082] By loading a hydrophilic functional layer on the surface of the stainless steel mesh membrane, the present invention enhances the anti-pollution performance of the membrane, extends the service life of the membrane, and solves the problem that the existing membrane materials are easily contaminated by oils and organic pollutants, resulting in a rapid decline in membrane flux.

[0083] By improving the anti-pollution performance and stability of the membrane, the present invention reduces the cleaning and replacement frequencies. Moreover, the base membrane is made of stainless steel with a relatively low cost, thereby reducing the operating cost and solving the problem of high cost caused by the need for frequent membrane cleaning and replacement in the existing technology.

[0084] By modifying the membrane material and optimizing the process parameters, the present invention improves the adaptability and treatment effect, and solves the problem that it is difficult for the existing technology to adapt to complex wastewater environments.

[0085] It should be noted that the parts not described in detail in the present invention are all conventional operating means in the art and are not the focus of the present invention.

[0086] The raw materials and reagents used in the specific implementation schemes of the present invention are all commercially available products.

[0087] Both the room temperature and normal temperature involved in the specific implementation schemes of the present invention refer to 20 - 30 °C.

[0088] Unless otherwise specified, the "%" for concentration in the specific implementation schemes of the present invention refers to mass percentage "wt. %".

[0089] The SSM parameters used in the examples of the present invention are 15 μm and 30 μm; the parameters of the polytetrafluoroethylene (PTFE) hydrophobic membrane are PTFE - 0.2 - N.

[0090] Example 1

[0091] The preparation steps of the conductive deammoniation composite membrane for treating oily high-ammonia-nitrogen wastewater include:

[0092] S1. Pretreatment of the base membrane

[0093] The SSM is successively ultrasonically cleaned with absolute ethanol, dilute hydrochloric acid solution, and deionized water, and the ultrasonic cleaning time for each time is 60 minutes. After the ultrasonic cleaning is completed, the SSM is placed in an oven and dried at a temperature of 50 °C until the surface is completely dry, obtaining the pretreated SSM, denoted as the SSM original membrane.

[0094] S2. Preparation of the alumina layer

[0095] Prepare a mixed solution of aluminum isopropoxide and acetic acid, where the solvent is ethanol, the concentration of aluminum isopropoxide is 0.2 mol / L, and the amount of acetic acid used is 3% of the amount of substance of aluminum isopropoxide. Immerse the pretreated SSM obtained in step S1 in the above mixed solution, place it in an oil bath at 70 °C for reaction, and the reaction time is 6 hours. During the reaction, continuously stir the solution to ensure that the coating can be formed evenly and stably; at the same time, gently shake the metal mesh every 30 minutes to prevent the membrane pores from being blocked. After the reaction, take out the SSM from the solution and rinse it with deionized water. After rinsing, place the SSM on filter paper to absorb the moisture, and then put it in an oven at 80 °C for drying for 3 hours to completely cure the coating, forming an alumina insulating layer on the surface of the SSM to obtain an Al2O3-SSM composite membrane.

[0096] S3: Coupling agent coating and curing

[0097] Prepare a KH792 solution with a concentration of 1.0%, and the solvent of this solution is a mixed solution of ethanol and deionized water with a volume ratio of 1:9. Immerse the SSM with an alumina insulating layer formed on its surface in step S2 in the KH792 solution for 30 minutes to ensure that the coupling agent is evenly coated on the surface. After impregnation, cure the SSM at a temperature of 70 °C for 2 hours to prepare a conductive layer (conductive film, electrothermal layer), denoted as KH792-Al2O3-SSM.

[0098] S4: Composite with the deaminated membrane

[0099] The KH792-Al2O3-SSM in step S3 and the deaminated membrane (PTFE) are composite by physical adhesion (the membrane module is fixed, and the membrane area is 12 cm 2 ), to obtain a conductive deamination composite membrane for treating oil-containing high-ammonia-nitrogen wastewater, denoted as KH792-Al2O3-SSM / PTFE.

[0100] Example 2

[0101] Compared with Example 1, the only difference is that KH792 is replaced with an equal amount of KH550, and the final product is denoted as KH550-Al2O3-SSM / PTFE.

[0102] Example 3

[0103] Compared with Example 1, the difference is that in step S2, aluminum isopropoxide is replaced with an equal amount of sodium metaaluminate, and acetic acid is replaced with an equal amount of formic acid, and the final product is denoted as KH792-Al2O3-SSM-2 / PTFE.

[0104] Example 4

[0105] Compared with Example 2, the difference lies in that aluminum isopropoxide in Step S2 is replaced with an equal amount of sodium metaaluminate, and acetic acid is replaced with an equal amount of formic acid. The final product is denoted as KH550-Al2O3-SSM-2 / PTFE.

[0106] Test Example 1

[0107] The composite membranes prepared in Examples 1-4 were placed in a membrane ammonia removal device. During the operation, the raw material liquid directly contacted the side of the conductive layer, and the absorbent liquid directly contacted the PTFE side. The pore size of the PTFE membrane was 0.15 μm, and the effective membrane area was 0.0012 m 2 , the temperature of the raw material liquid was 60 °C, pH = 13, and the flow rate was 0.6 L / min. The main components of the raw material liquid were a ammonium chloride solution with a concentration of 2000 mg / L and 1000 mg / L of coal tar. The absorbent liquid was a 0.75 mol / L sulfuric acid solution with a flow rate of 0.2 L / min. A current of 10 A was applied across the conductive layer.

[0108] Figure 2 is the ammonia nitrogen removal rate of the composite membranes in Examples 1-4 during ammonia removal. Among them, a is Example 1, b is Example 2, c is Example 3, and d is Example 4. As can be seen from the figure, the ammonia absorption rate of Example 1 can reach 95.85%, the ammonia absorption rate of Example 2 can reach 93.18%, and the ammonia absorption rates of Examples 3 and 4 can reach over 91%.

[0109] Figure 3 is the rejection rate of coal tar by the composite membranes in Examples 1-4 during ammonia removal. Among them, a is Example 1, b is Example 2, c is Example 3, and d is Example 4. As can be seen from the figure, the rejection rates of Examples 1-4 for kerosene can all reach over 99.99%.

[0110] After running for 12 h, the contact angle of the membrane after operation was tested and compared with the contact angle before operation. The results are shown in Table 1.

[0111] Table 1

[0112]

[0113] It can be seen from the data in Table 1 that the contact angles of the membrane materials prepared in Examples 1-4 of the present invention changed little after running for 12 h, indicating that the membrane materials still maintained good hydrophilicity and stable separation performance.

[0114] The prepared membrane was operated in a membrane ammonia stripping device. Ammonia on the feed side passed through the membrane pores and was absorbed by the dilute sulfuric acid solution on the absorbent side. After the operation, the ammonia content in the absorbent side was measured and compared with the initial ammonia content in the feed side. The absorption rate could reach over 99%, effectively realizing the resource recovery of ammonia. Subsequently, the contact angle of the membrane after operation was tested, and the contact angle on the membrane remained the same as the water contact angle before operation, indicating that the membrane surface was not contaminated or wetted by oil pollutants during the operation.

[0115] Test Example 2

[0116] The pH of the feed solution in Test Example 1 was adjusted from 13 to 7 or 11. Specifically:

[0117] KH792 - Al2O3 - SSM / PTFE obtained in Example 1 was used and placed in a membrane ammonia stripping device. During the operation, the feed solution directly contacted the conductive layer side, and the absorbent directly contacted the PTFE side. The pore size of the PTFE membrane was 0.15 μm, and the effective membrane area was 0.0012 m 2 , the temperature of the feed solution was 60 °C, pH = 7 or 11, the flow rate was 0.6 L / min, the main components of the feed solution were ammonium chloride solution with a concentration of 2000 mg / L and coal tar with a concentration of 1000 mg / L, the absorbent was 0.75 mol / L sulfuric acid solution, and the flow rate was 0.2 L / min. A current of 10 A was applied across the conductive layer.

[0118] Figure 4 shows the ammonia nitrogen removal rate during the ammonia stripping process when the pH of the feed solution was 7 and 11. It can be seen from the figure that when the pH of the feed solution was adjusted from 11 to 7 and the operation lasted for 6 h, the ammonia absorption rate decreased to 17.56%; when the pH of the feed solution was adjusted from 13 to 11 and the operation lasted for 6 h, the ammonia absorption rate decreased to 51.66%.

[0119] Figure 5 shows the rejection rate of coal tar during the ammonia stripping process when the pH of the feed solution was 7 and 11. It can be seen from the figure that the change in the pH of the feed solution had little effect on the rejection rate of coal tar.

[0120] Test Example 3

[0121] The temperature of the feed solution in Test Example 1 was adjusted from 60 °C to 20 °C, and other parameters remained unchanged. Specifically:

[0122] KH792 - Al2O3 - SSM / PTFE obtained in Example 1 was used and placed in a membrane ammonia stripping device. During the operation, the feed solution directly contacted the conductive layer side, and the absorbent directly contacted the PTFE side. The pore size of the PTFE membrane was 0.15 μm, and the effective membrane area was 0.0012 m 2, the temperature of the raw material liquid is 20°C, pH = 13, and the flow rate is 0.6 L / min. The main components of the raw material liquid are an ammonium chloride solution with a concentration of 2000 mg / L and coal tar with a concentration of 1000 mg / L. The absorbent liquid is a 0.75 mol / L sulfuric acid solution with a flow rate of 0.2 L / min. A current of 10 A is applied across the conductive layer.

[0123] Figure 6 shows the ammonia nitrogen removal rates during the deammoniation process when the temperature of the raw material liquid is 60°C and 20°C. It can be seen from the figure that when the temperature of the raw material liquid is adjusted from 60°C to 20°C and the operation lasts for 6 h, the ammonia absorption rate drops from 73.97% to 45.27%.

[0124] Figure 7 shows the rejection rates of coal tar during the deammoniation process when the temperature of the raw material liquid is 60°C and 20°C. It can be seen from the figure that the change in the temperature of the raw material liquid has little effect on the rejection rate of coal tar.

[0125] Test Example 4

[0126] Adjust the concentration of the sulfuric acid solution used as the absorbent liquid in Test Example 1 to 0 mol / L or 0.25 mol / L, and keep other parameters unchanged. Specifically:

[0127] Use the KH792 - Al2O3 - SSM / PTFE obtained in Example 1 and place it in the membrane deammoniation device. During the operation, the raw material liquid directly contacts one side of the conductive layer, and the absorbent liquid directly contacts the PTFE side. The pore size of the PTFE membrane is 0.15 μm, and the effective membrane area is 0.0012 m 2 , the temperature of the raw material liquid is 60°C, pH = 13, and the flow rate is 0.6 L / min. The main components of the raw material liquid are an ammonium chloride solution with a concentration of 2000 mg / L and coal tar with a concentration of 1000 mg / L. The absorbent liquid is a sulfuric acid solution with a concentration of 0 mol / L or 0.25 mol / L and a flow rate of 0.2 L / min. A current of 10 A is applied across the conductive layer.

[0128] Figure 8 shows the ammonia nitrogen removal rates during the deammoniation process when the concentration of the sulfuric acid solution used as the absorbent liquid is 0 mol / L and 0.25 mol / L. It can be seen from the figure that when the concentration of the sulfuric acid solution used as the absorbent liquid is adjusted from 0.75 mol / L to 0 mol / L and the operation lasts for 6 h, the ammonia absorption rate drops to 21.51%; when the concentration of the sulfuric acid solution used as the absorbent liquid is adjusted from 0.75 mol / L to 0.25 mol / L and the operation lasts for 6 h, the ammonia absorption rate drops to 69.4%.

[0129] Figure 9 shows the rejection rates of coal tar during the deammoniation process when the concentration of the sulfuric acid solution used as the absorbent liquid is 0 mol / L and 0.25 mol / L. It can be seen from the figure that the change in the concentration of the sulfuric acid solution has little effect on the rejection rate of coal tar.

[0130] Test Example 5

[0131] Reduce the current applied at both ends of the conductive layer in the solution of Test Example 1. The specific steps are as follows:

[0132] Use the KH792-Al2O3-SSM / PTFE obtained in Example 1 and place it in the membrane deammoniation device. During the operation, the raw material liquid directly contacts one side of the conductive layer, and the absorption liquid directly contacts the PTFE side. The pore diameter of the PTFE membrane is 0.3 μm, and the effective membrane area is 0.0012 m 2 , the temperature of the raw material liquid is 60 °C, pH = 13, and the flow rate is 0.6 L / min (prepared from distilled water and ammonium chloride, with a concentration of about 2000 mg / L). The absorption liquid is 0.75 mol / L sulfuric acid solution with a flow rate of 0.2 L / min. No current is applied at both ends of the conductive layer.

[0133] Figure 10 It shows the trend of the ammonia nitrogen removal rate of the electrothermal layer changing with time under different current conditions (10 A and 0 A). It can be seen from the figure that under the condition of 10 A current, the ammonia nitrogen removal rate increases significantly with time and approaches 90% after 12 hours; while under the condition of 0 A current, although the removal rate also increases with time, the growth rate is slower and is about 40% after 12 hours. This indicates that the presence of current significantly improves the efficiency of the electrothermal layer in removing ammonia nitrogen.

[0134] Figure 11 It is the retention rate (removal rate) of coal tar during the deammoniation process when the conductive membrane is connected to the power supply and not connected to the power supply. It can be seen from the figure that connecting or not connecting the power supply has little effect on the retention rate of coal tar.

[0135] Example 5

[0136] Compared with Example 1, the difference is only that the concentration of the KH792 solution is 2.0%.

[0137] Figure 12 It is the SEM image of one side of the conductive layer of the composite membrane obtained in Example 5.

[0138] Comparative Example 1

[0139] Compared with Example 1, the difference is only that the Al2O3-SSM composite membrane obtained in step S2 is not coated and cured with a coupling agent, but directly compounded with the deaminated membrane. The steps are as follows:

[0140] S1. Pretreatment of the base membrane

[0141] The SSM was ultrasonically cleaned successively with absolute ethanol, dilute hydrochloric acid solution and deionized water, and the ultrasonic cleaning time was 60 minutes each time. After ultrasonic cleaning, the SSM was placed in an oven and dried at 50 °C until the surface was completely dry, obtaining the pretreated SSM, denoted as the SSM original film.

[0142] S2. Preparation of alumina layer

[0143] A mixed solution of aluminum isopropoxide and acetic acid was prepared, where the solvent was ethanol, the concentration of aluminum isopropoxide was 0.2 mol / L, and the dosage of acetic acid was 3% of the amount of substance of aluminum isopropoxide. The pretreated SSM obtained in step S1 was immersed in the above mixed solution and placed in an oil bath at 70 °C for reaction for 6 hours. During the reaction, the solution was continuously stirred to ensure that the coating could form evenly and stably; meanwhile, the metal mesh was gently shaken every 30 minutes to prevent membrane pore blockage. After the reaction, the SSM was taken out of the solution and rinsed with deionized water. After rinsing, the SSM was blotted dry on filter paper and then placed in an oven at 80 °C for drying for 3 hours to completely cure the coating, forming an alumina insulating layer on the surface of the SSM, obtaining the conductive layer.

[0144] S3: Composite with the deaminated membrane

[0145] The conductive membrane in step S2 was composited with the deaminated membrane by physical attachment (the membrane module was fixed, and the membrane area was 12 cm 2 ), obtaining the composite membrane, denoted as Al2O3-SSM / PTFE.

[0146] This comparative example only constructed an alumina insulating layer on the surface of the SSM and did not introduce a KH792 coupling agent coating, forming a contrast with Example 1, and was used to verify the influence of the coupling agent coating process on the membrane performance by the method in Test Example 1.

[0147] Figure 13 For the ammonia nitrogen removal rates of the composite membranes in Example 5 and Comparative Example 1 during the deamination process. As can be seen from the figure, the ammonia absorption rate of Comparative Example 1 (0%) was only 46.6%, and the ammonia absorption rate was 84.7% when the concentration of the KH792 solution was 2.0%.

[0148] Figure 14 For the rejection rates of the composite membranes in Example 5 and Comparative Example 1 for coal tar during the deamination process. As can be seen from the figure, the coal tar rejection rate of Comparative Example 1 (0% wt KH792) was only 39.45%.

[0149] Figure 13 and Figure 14, indicating that after modification with silane coupling agent, the hydrophilicity and anti-pollution performance of the membrane surface are enhanced, the problem of oil substances passing through the metal mesh holes and blocking the deamination membrane holes is reduced, so that ammonia molecules can more easily pass through the membrane holes, and the removal rate of ammonia nitrogen is improved. Therefore, the addition of silane coupling agent plays an important role in improving the performance of the deamination membrane.

[0150] Comparative Example 2

[0151] Compared with Example 1, the difference is only that the alumina insulating layer is not prepared on the pretreated SSM, and the steps are as follows:

[0152] S1. Substrate membrane pretreatment

[0153] The SSM was ultrasonically cleaned successively with absolute ethanol, dilute hydrochloric acid solution and deionized water, and the ultrasonic cleaning time was 60 minutes each time. After the ultrasonic cleaning was completed, the SSM was placed in an oven and dried at a temperature of 50 °C until the surface was completely dry to obtain the pretreated SSM, denoted as SSM original membrane.

[0154] S2: Coupling agent coating and curing

[0155] A KH792 solution with a concentration of 1.0% was prepared, and the solvent of this solution was a mixed solution of ethanol and deionized water with a volume ratio of 1:9. The SSM original membrane in step S1 was immersed in the KH792 solution for 30 minutes to ensure uniform coating of the coupling agent on the surface. After the immersion was completed, the SSM was cured at a temperature of 70 °C for 2 hours to obtain the conductive layer.

[0156] S3: Composite with the deamination membrane

[0157] The conductive layer in step S3 and the deamination membrane (PTFE) were composite by physical attachment (the membrane module was fixed, and the membrane area was 12 cm 2 ), to obtain the composite membrane, denoted as KH792-SSM / PTFE.

[0158] In this comparative example, the alumina insulating layer was not constructed on the surface of the SSM, and the coupling agent was directly coated, forming a contrast with Example 1, and the method in Test Example 1 was used to verify the influence of the alumina insulating layer on the membrane performance.

[0159] Figure 15Ammonia nitrogen removal rates of the composite membranes in Example 1 and Comparative Example 2 during the deamination process. As can be seen from the figure, under the condition of having an alumina coating, the ammonia nitrogen removal rate increases significantly with time and reaches 91.2% after 12 hours; while without an alumina coating, the growth rate of the removal rate is slower and it is 45.9% after 12 hours. This indicates that the presence of the alumina coating significantly improves the ammonia nitrogen removal efficiency. The alumina coating can prevent the direct passage of current through the stainless steel mesh, thereby reducing power loss and improving the energy efficiency of the system. At the same time, it plays a role in improving the heat conduction efficiency and promoting the uniform distribution of heat, thus accelerating the ammonia nitrogen removal process and improving the removal efficiency. In addition, the alumina coating can also protect the stainless steel mesh from corrosion, extend its service life and maintain its deamination performance.

[0160] Figure 16 The rejection rates of coal tar by the composite membranes in Example 1 and Comparative Example 2 during the deamination process. As can be seen from the figure, the presence or absence of the alumina coating has little effect on the rejection rate of coal tar.

[0161] Comparative Example 3

[0162] Compared with Example 4, the difference is only that the Al2O3-SSM composite membrane obtained in step S2 is not coated and cured with a coupling agent, and is directly compounded with the deaminated membrane to obtain a composite membrane denoted as Al2O3-SSM-2 / PTFE.

[0163] This comparative example only constructs an alumina insulating layer on the surface of the SSM and does not introduce a KH550 coupling agent coating, forming a contrast with Example 4, and is used to verify the influence of the coupling agent coating process on the membrane performance by the method in Test Example 1.

[0164] Figure 17 Ammonia nitrogen removal rates of the composite membranes in Example 4 and Comparative Example 3 during the deamination process. The figure shows the variation of the ammonia nitrogen removal rates of the two composite membranes (KH550-Al2O3-SSM-2 / PTFE and Al2O3-SSM-2 / PTFE) with time under the conditions of having or not having KH550. After 12 hours, the ammonia nitrogen removal rate of the KH550-Al2O3-SSM-2 / PTFE composite membrane is close to 90%, while that of the composite membrane without KH550 is about 45%.

[0165] Figure 18 The rejection rates of coal tar by the composite membranes in Example 4 and Comparative Example 3 during the deamination process. As can be seen from the figure, the coal tar rejection rate of Comparative Example 3 (0%wt KH550) is only 36.23%.

[0166] Figure 17 and Figure 18, indicating that after modification with silane coupling agent, the hydrophilicity and anti-pollution performance of the enhanced membrane are improved, reducing the problem of oil substances passing through the metal mesh pores and clogging the deammonification membrane pores, thus making ammonia molecules more likely to pass through the membrane pores and increasing the removal rate of ammonia nitrogen. Therefore, the addition of silane coupling agent plays an important role in improving the performance of the deammonification membrane.

[0167] Comparative Example 4

[0168] Compared with Example 2, the difference is only that the alumina insulating layer is not prepared on the pretreated SSM, and the obtained composite membrane is denoted as KH550-SSM / PTFE.

[0169] This comparative example did not construct an alumina insulating layer on the surface of SSM and directly coated the coupling agent, forming a contrast with Example 2, and was used to verify the influence of the alumina insulating layer on the membrane performance by the method in Test Example 1.

[0170] Figure 19 Ammonia nitrogen removal rates of the composite membranes of Example 2 and Comparative Example 4 during deammonification. As can be seen from the figure, under the condition of having an alumina coating, the ammonia nitrogen removal rate increased significantly with time and reached 93.18% after 12 hours; while without an alumina coating, the growth rate of the removal rate was slower and was 39.98% after 12 hours. This indicates that the presence of the alumina coating significantly improves the ammonia nitrogen removal efficiency. The alumina coating can prevent the direct passage of current through the stainless steel mesh, thereby reducing power loss and improving the energy efficiency of the system. At the same time, it plays a role in improving the heat conduction efficiency and promoting uniform heat distribution, thus accelerating the ammonia nitrogen removal process and increasing the removal efficiency. In addition, the alumina coating can also protect the stainless steel mesh from corrosion, extend its service life and maintain its deammonification performance.

[0171] Figure 20 The rejection rates of coal tar by the composite membranes of Example 2 and Comparative Example 4 during deammonification. As can be seen from the figure, the presence or absence of the alumina coating has little effect on the rejection rate of coal tar.

[0172] Comparative Example 5

[0173] Compared with Example 1, the difference is only that the reaction time in the 70°C oil bath in Step S2 is adjusted to 2 h, and the obtained composite membrane is denoted as KH792-Al2O3-SSM-T2 / PTFE.

[0174] This comparative example formed a contrast with Example 1 by shortening the oil bath reaction time in Step S2 (2 hours vs 6 hours in Example 1), and was used to verify the influence of the reaction time on the film-forming effect of the alumina insulating layer and the membrane performance by the method in Test Example 1.

[0175] Figure 21Ammonia nitrogen removal rates of the composite membranes of Example 1 and Comparative Example 5 during the ammonia removal process. As can be seen from the figure, under the condition of a 6-hour reaction time, the ammonia nitrogen removal rate increased significantly with time and reached 95.85% after 12 hours; while under the condition of a 2-hour reaction time, the removal rate decreased to 47.80%. This is because the reaction time was insufficient (only 2 hours), and the alumina insulating layer failed to completely cover the SSM metal mesh substrate.

[0176] Figure 22 Interception rates of coal tar by the composite membranes of Example 1 and Comparative Example 5 during the ammonia removal process. As can be seen from the figure, too short a reaction time for forming the alumina coating had little effect on the interception rate of coal tar.

[0177] Comparative Example 6

[0178] Compared with Example 1, the only difference is that the reaction time in the 70°C oil bath in Step S2 was adjusted to 8 hours, and the obtained composite membrane was denoted as KH792-Al2O3-SSM-T8 / PTFE.

[0179] This comparative example formed a contrast with Example 1 by extending the oil bath reaction time in Step S2 (8 hours vs. 6 hours in Example 1), and the method in Test Example 1 was used to verify the influence of the reaction time on the film-forming effect of the alumina insulating layer and the film properties.

[0180] Figure 23 Ammonia nitrogen removal rates of the composite membranes of Example 1 and Comparative Example 6 during the ammonia removal process. As can be seen from the figure, under the condition of a 6-hour reaction time, the ammonia nitrogen removal rate increased significantly with time and reached 95.85% after 12 hours; while under the condition of an 8-hour reaction time, the removal rate decreased to 85.76%. This is because a long reaction time easily led to excessive deposition and agglomeration of alumina on the SSM surface, destroying the uniformity and dense structure of the insulating layer, and thus having a negative impact on the subsequent performance of the composite membrane.

[0181] Figure 24 Interception rates of coal tar by the composite membranes of Example 1 and Comparative Example 6 during the ammonia removal process. As can be seen from the figure, too long a reaction time for forming the alumina coating had little effect on the interception rate of coal tar.

[0182] Test Example 6

[0183] Figure 25 Surface morphology diagrams of the SSM original membrane and KH792-Al2O3-SSM in Example 1.

[0184] Figure 26 Element distribution diagrams of KH792-Al2O3-SSM in Example 1.

[0185] By Figure 25 - Figure 26It can be seen that the coating distribution after coating with KH792 is uniform, and the surface of the metal mesh is evenly coated. The gap between the metal wires has decreased, the coating thickness is just right, the coating surface is smooth and delicate, showing good adhesion and uniformity of KH792 at a concentration of 1.0%, and the coating has good denseness at this concentration.

[0186] Figure 27 Figure 4 shows the XPS spectra of the SSM original film and KH792-Al2O3-SSM in Example 1. Among them, (a) is the full XPS spectrum of the SSM original film and KH792-Al2O3-SSM, (b) is the high-resolution spectrum of O1s, (c) is the high-resolution spectrum of C1s, (d) is the high-resolution spectrum of N1s, and (e) is the high-resolution spectrum of Si2p. As can be seen from the figure, in (a), the SSM has obvious C1s and O1s peaks at 285.3 eV and 535.2 eV. As the reaction progresses, new peaks appear in the XPS spectrum of KH792-SSM at 398.4 eV and 100.2 eV, which are N1s and Si2p respectively, due to the hydrolysis and condensation reaction of KH792 on the SSM surface. In (b) and (c), compared with the SSM, the C1s fitting curve spectrum of KH792-SSM newly appears two sub-peaks of C-N (285.3 eV) and C-Si (283.8 eV). Among them, the C-N bond is mainly possessed by KH792 itself, and the C-Si bond mainly results from the hydrolysis and condensation of KH792. In (d), the two sub-peaks of KH792-SSM at 399.9 eV and 398.3 eV are mainly attributed to -NH- and -NH2 of KH792. In (e), the Si2p of KH792-SSM is fitted into two sub-peaks of Si-O-Si (101.8 eV) and Si-C (100.6 eV), which are mainly produced by the hydrolysis and condensation reaction of KH792. Through comprehensive analysis of the XPS energy spectra of KH792-SSM and SSM, its structure and elemental composition both verify that KH792 undergoes hydrolysis reaction and at the same time undergoes condensation reaction with the hydroxyl groups on the metal surface, and the coupling agent is grafted on the SSM surface to form a modified coating.

[0187] Figure 28SEM and EDS diagrams of KH792-Al2O3-SSM-2 / PTFE in Example 3. It can be seen from the figures that compared with the alumina insulating layer prepared from aluminum isopropoxide and acetic acid in Example 1, the alumina insulating layer prepared from sodium aluminate and formic acid system shows a higher porosity (weight method measurement results: the porosity of the aluminum isopropoxide + acetic acid system is 44.81%, and that of the sodium aluminate + formic acid system is 51.72%). And its EDS spectrum shows that the proportion of Fe element reaches 54.3% and the proportion of Al element is only 1.25%, indicating that the alumina insulating layer does not completely cover the stainless steel mesh (the main component of the stainless steel mesh is Fe). This is mainly because in the organic system composed of aluminum isopropoxide and acetic acid, acetic acid, as a weak acid, releases hydrogen ions slowly, the pH change of the reaction system is mild, the aluminum hydroxide intermediate is generated evenly and has good dispersibility, and the alumina particles formed after curing are arranged tightly. The pores are mainly composed of regular gaps between uniform particles, so the porosity is low (44.81%). In the system of sodium aluminate (inorganic aluminum source) and formic acid (strong acid catalyst), formic acid has strong acidity and fast hydrogen ion release rate, resulting in a drastic change in the pH of the reaction system, and the aluminum hydroxide intermediate is generated rapidly and agglomerates; at the same time, sodium aluminate, as an inorganic aluminum source, has a high hydrolysis reaction rate and is easy to form large-size particle clusters. Such irregular packing between agglomerated particles and clusters will introduce a large number of non-uniform pores (such as random gaps between particles and voids inside clusters), so macroscopically, the porosity is significantly increased to 51.72%. At the same time, due to the uniform dispersion of the aluminum hydroxide intermediate in the aluminum isopropoxide + acetic acid system, the alumina insulating layer formed after curing is continuous and dense, which can effectively cover the surface of the stainless steel mesh. Therefore, the proportion of Al element in the EDS detection is high (the Al content corresponding to Example 1 should be significantly higher than Fe). In the sodium aluminate + formic acid system, due to the serious agglomeration of aluminum hydroxide particles and large cluster size, there are a large number of uncovered "bare areas" in the alumina insulating layer, and the Fe element of the stainless steel mesh substrate is directly exposed.

[0188] Figure 29 SEM diagrams of the SSM original film and Al2O3-SSM / PTFE in Comparative Example 1, and the element distribution diagram of SSM-Al2O3 in Al2O3-SSM / PTFE. It can be seen from the figures that the SSM original film has large roughness, intertwined structure, uneven surface and voids; the surface morphology of SSM changes significantly after forming the alumina insulating layer. It can be seen from its SEM diagram and element diagram that good dispersion of nano-Al2O3 can be clearly seen on the surface, the SSM is covered by a uniform white film, and Al2O3 is successfully loaded on the SSM original film and evenly distributed, making the surface of the composite film smooth and uniform. This indicates that the specific process selected in the present invention realizes the effective loading and uniform dispersion of Al2O3 on the surface of SSM, laying a foundation for the excellent properties of the composite film in terms of wear resistance, corrosion resistance, high temperature resistance, etc., and providing a stable adhesion layer for the subsequent further modification and optimization of the film.

[0189] Figure 30 SEM and EDS diagrams of the alumina insulating layer in KH792 - Al2O3 - SSM - T2 / PTFE with a preparation reaction time of 2 h in Comparative Example 5. As can be seen from the figure, through EDS energy spectrum analysis, it is known that the Al content on the membrane surface is significantly lower than that of Fe. Combining with the characterization of the exposed area of the metal mesh substrate in the SEM diagram, it shows that due to insufficient reaction time (only 2 hours), the alumina insulating layer fails to completely cover the SSM metal mesh substrate. It shows that under short - time reaction conditions, the hydrolysis - condensation reaction of aluminum isopropoxide and acetic acid does not proceed sufficiently, resulting in insufficient deposition of the alumina precursor on the metal mesh surface and unable to form a continuous and dense insulating coating. The uncovered metal mesh substrate area may cause current leakage or interface defects, thereby affecting the uniformity of the subsequent coupling agent coating and the separation performance of the membrane material. Experimental data show that the ammonia absorption rate of the composite membrane prepared under this reaction time decreases by 12.3% during the ammonia removal process compared with Example 1, further verifying the key role of the complete coverage of the alumina insulating layer in the sufficiency of the reaction.

[0190] Figure 31 SEM diagram of the alumina insulating layer in KH792 - SSM - Al2O3 - T8 / PTFE with a preparation reaction time of 8 h in Comparative Example 6. In the figure, the preparation reaction time of the alumina insulating layer of this composite membrane is set to 8 hours. Experiments and characterization analysis show that an appropriate reaction time needs to be controlled for the preparation of the alumina insulating layer. An overly long reaction time easily leads to excessive deposition and agglomeration of alumina on the SSM surface, destroying the uniformity and dense structure of the insulating layer, and thus having a negative impact on the subsequent performance of the composite membrane.

[0191] Figure 32 Schematic diagram of the modification preparation of the conductive layer (electric heating layer) of the composite membrane and the ammonia removal and oil resistance mechanism of the composite membrane. The ammonia removal device of the present invention includes: a composite membrane assembly formed by laminating a conductive membrane (electric heating layer) and a polytetrafluoroethylene (PTFE) hydrophobic membrane, and a supporting DC power supply unit. In the composite membrane assembly, the conductive membrane (electric heating layer) and the PTFE hydrophobic membrane are laminated in a face - to - face fitting manner to form a double - membrane separation structure, where the conductive membrane (electric heating layer) side is used to contact the ammonia - containing wastewater (such as coking wastewater), and the PTFE hydrophobic membrane side is used to contact the dilute sulfuric acid absorbent. The effective membrane area of the composite membrane assembly is 0.0012 m 2 , by controlling the ammonia - containing wastewater flow rate of 0.6 L / min, the absorbent flow rate of 0.2 L / min, and the temperature of 60 °C, combined with the thermal effect of the applied electric field, a highly efficient separation system of "pressure - difference driving + electro - thermal synergy" is formed. Through experimental verification, the device can maintain a coal tar interception rate of ≥99.99% while significantly improving the mass transfer efficiency of ammonia, realizing the deep removal and recovery of ammonia nitrogen in coking wastewater.

[0192] Figure 1Schematic structural diagram of the device for treating oily ammonia - nitrogen wastewater with a conductive ammonia - removal membrane in Example 1, where the reference numerals are: water storage tank 1, hot water bath assembly 2, valve 3, pump 4, conductive layer 5, ammonia - removal membrane 6, DC power supply 7, valve 8, cold water bath assembly 9, pump 10, flowmeter 11, product water tank 12.

[0193] The operating principle of the device is as follows:

[0194] Interface layer construction: When the ammonia - containing wastewater flows from one side of the conductive layer, due to the liquid - repellent property of the PTFE hydrophobic membrane, a stable liquid - vapor interface layer is naturally formed on the membrane surface. The dilute sulfuric acid absorbent (0.75 mol / L) on the other side covers the surface of the PTFE hydrophobic membrane in a laminar flow state, and its vapor pressure is significantly lower than that on the ammonia - containing wastewater side, forming a transmembrane vapor pressure difference to drive the migration of ammonia molecules.

[0195] Phase change separation process: Ammonia in the ammonia - containing wastewater permeates through the microporous structure of the PTFE hydrophobic membrane in a vapor state, undergoes a phase change on the side of the dilute sulfuric acid absorbent and is chemically absorbed (to form ammonium sulfate), and the continuous separation of volatile target substances is achieved by maintaining the vapor pressure difference on both sides.

[0196] Electric - field strengthening mechanism: An external voltage with an input power density of 20 kW / m is applied to the conductive membrane (electric heating layer) through the DC power supply unit. By utilizing the resistance characteristics of the metal mesh in the conductive membrane (electric heating layer), rapid local heating is achieved, which promotes the evaporation rate of the liquid on the surface of the PTFE hydrophobic membrane, further increases the transmembrane vapor pressure difference, and strengthens the mass transfer process. 2 For each embodiment in this specification, a progressive description is adopted. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0197] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0198] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A conductive deammoniation composite membrane for treating oily wastewater with high ammonia nitrogen content, characterized in that, It includes a conductive film and a deaminated film; The conductive film includes a stainless steel wire mesh substrate, an alumina insulating middle layer, and a hydrophilic outer layer; The deaminated film includes at least one of a polytetrafluoroethylene film, a polypropylene film, and a polyvinylidene fluoride film.

2. A method for preparing a conductive deammoniation composite membrane for treating oily ammonia-nitrogen wastewater according to claim 1, characterized in that the steps It includes: Immerse the stainless steel wire mesh in a mixed solution containing an aluminum source and an acidic catalyst, stir and react, then dry to form an alumina insulating layer on the surface of the stainless steel wire mesh. Subsequently, immerse it in a silane coupling agent solution and perform a curing treatment to obtain the conductive film; Composite the conductive film with the deaminated film to obtain the conductive deamination composite film for treating oil-containing high-ammonia-nitrogen wastewater.

3. The preparation method according to claim 2, characterized in that, The pore size range of the stainless steel wire mesh is 10 - 40 μm; and / or, the solvent in the mixed solution is ethanol, the concentration of the aluminum source is 0.2 - 0.4 mol / L, and the dosage of the acidic catalyst is 2 - 5% of the amount of substance of the aluminum source.

4. The preparation method according to claim 2, wherein The aluminum source includes at least one of aluminum isopropoxide, aluminum isobutoxide, and sodium metaaluminate; and / or, the acidic catalyst includes at least one of acetic acid, formic acid, propionic acid, and butyric acid; and / or, the temperature of the stirring reaction is 60 - 80 °C, the time is 4 - 6 h; and / or, the drying temperature is 80 - 90 °C.

5. The preparation method according to claim 2, wherein The solvent in the silane coupling agent solution is ethanol and water, and the concentration of the silane coupling agent is 0.5 - 2 wt.%; and / or, the silane coupling agent in the silane coupling agent solution includes at least one of KH550, KH560, KH570, KH580, KH590, KH602, KH791, and KH792; and / or, the immersion time in the silane coupling agent solution is 10 - 30 min; and / or, the temperature of the curing treatment is 50 - 70 °C, the time is 1 - 2 h; and / or, the composite of the conductive film and the deaminated film is to composite the conductive film and the deaminated film by physical adhesion.

6. The preparation method according to claim 2, characterized in that, It also includes a pretreatment step for the stainless steel wire mesh: ultrasonically clean the stainless steel wire mesh with absolute ethanol, dilute hydrochloric acid solution, and deionized water in sequence for 30 - 60 min.

7. Application of the conductive deamination composite film for treating oil-containing high-ammonia-nitrogen wastewater according to claim 1 in the treatment of high-ammonia-nitrogen oil-containing wastewater.

8. A membrane deammoniation device, characterized in that, It includes the conductive deamination composite film for treating oil-containing high-ammonia-nitrogen wastewater according to claim 1 and a DC power supply unit; The DC power supply unit applies a current to the conductive deamination composite film for treating oil-containing high-ammonia-nitrogen wastewater.

9. The membrane ammonia removal device according to claim 8, characterized in that, The range of the current is 1 - 10 A.

10. Application of the membrane deamination device according to claim 8 or 9 in the treatment of high-ammonia-nitrogen oil-containing wastewater.

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