Preparation method of polytetrafluoroethylene composite fiber membrane for sulfur removal based on solution injection

Abstract

The invention discloses a preparation method of a polytetrafluoroethylene composite fiber membrane for sulfur removal based on solution injection. The preparation method comprises the following steps: selecting a polytetrafluoroethylene microporous membrane as a receiving bottom membrane and placing the polytetrafluoroethylene microporous membrane on a liquid injection spinning receiving web curtain; mixing the powdery Bayer red mud, the polytetrafluoroethylene dispersion emulsion and the polyoxyethylene solution to prepare a mixed solution, and uniformly stirring; the mixed solution serves as a spinning solution and flows through a spinneret orifice under the pressurization effect of a plunger; the spinning solution is drawn to be long and thin to form microscale fibers, and the microscale fibers are gathered on the surface of a polytetrafluoroethylene microporous membrane on a receiving web curtain to form an initial composite fiber membrane; and performing heat treatment to obtain the final composite fiber membrane. According to the polytetrafluoroethylene composite fiber membrane prepared by the invention, the concentration of sulfur dioxide can be controlled from gt; 150 mg / m < 3 > is reduced to 15 mg / m < 3 >, and the removal efficiency is higher than 90%; the filtering efficiency gt of removing micro-scale solid particles in the smoke dust; therefore, the dual performance of filtering and sulfur removal of the waste incineration smoke dust is realized.

Description

Technical Field

[0001] The invention relates to a method for preparing a polytetrafluoroethylene fiber membrane, in particular to a method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying. Background Art

[0002] With the rapid development of urbanization, incineration has become the primary method for harmlessly disposing of municipal solid waste. Currently, waste incineration dust purification materials primarily consist of coated needled felt, a composite of polytetrafluoroethylene (PTFE) microporous membranes and needled felt. The purified PTFE microporous membranes are primarily made from dispersed PTFE powders through a biaxial stretching process. These membranes come into contact with waste incineration dust to intercept solid particles. Existing PTFE microporous membranes are chemically stable and insoluble in conventional solvents, earning them the nickname "King of Plastics." They also offer excellent high and low temperature resistance (-260°C to 260°C), a non-stick surface, and a low coefficient of friction, making them ideal for waste incineration dust filter membranes.

[0003] Waste incineration dust contains large amounts of sulfur dioxide. Existing polytetrafluoroethylene (PTFE) microporous membranes have limited performance and are unable to effectively remove this sulfur dioxide from waste incineration dust. Direct sulfur dioxide release into the atmosphere causes severe air pollution. Furthermore, atmospheric sulfur dioxide undergoes photochemical reactions, dissolves in atmospheric water vapor, and ultimately falls to the surface as acid rain, contaminating water and soil resources.

[0004] In existing waste incineration dust purification technologies, sulfur dioxide in the dust is mainly removed by additional pre-treatment systems or post-treatment systems. Patent document CN103127795A discloses a method and system for treating flue gas, which removes sulfur dioxide from the dust through external limestone or activated carbon; Patent document CN217511550U discloses a combined sulfur dioxide removal system for a domestic waste incinerator, which uses an external desulfurization device to remove sulfur dioxide; Patent document CN115779674A uses a semi-dry reaction tower to remove sulfur from waste incineration dust; Patent document CN215027562 ...5027562 discloses a combined sulfur dioxide removal system for a domestic waste incinerator, which uses an external desulfurization device to remove sulfur dioxide; Patent document CN115779674A uses a semi-dry reaction tower to remove sulfur from waste incineration dust; Patent document CN215027562 discloses a method and system for treating flue gas, which removes sulfur dioxide from the dust through external limestone or activated carbon; Patent document CN215027562 discloses a combined sulfur dioxide removal system for a domestic waste incinerator, which uses an external desulfurization device to remove sulfur dioxide; Patent document CN115779674A uses a semi-dry reaction tower to remove sulfur from waste incineration dust; Patent document CN215027562 discloses a combined sulfur dioxide removal system for a domestic waste incin U announced a comprehensive treatment system for waste incineration flue gas, which uses an external catalytic reduction module to remove sulfur; patent CN117065540A uses an external ammonia spray system to remove sulfur from waste incineration dust; patent document CN115672006A adds baking soda to an external desulfurization tower to remove sulfur from waste incineration dust; patent document CN116688745A uses a desulfurizer added to the high-temperature section of incineration and combined with a subsequent desulfurization tower technology to remove sulfur from waste incineration dust.

[0005] As can be seen from the above, in the prior art, an external equipment system is used to remove sulfur dioxide from waste incineration dust, which has defects such as complex process and high energy consumption.

[0006] In order to solve the defects of the existing technology, the present invention uses liquid spraying technology to composite micro-scale fibers containing Bayer red mud catalytic components with polytetrafluoroethylene microporous membranes to give the garbage incineration dust filter material the function of removing sulfur dioxide in the flue gas. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to remove sulfur dioxide from waste incineration dust with high efficiency and low energy consumption by using a polytetrafluoroethylene microporous membrane.

[0008] To achieve the above purpose, a method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying, comprising the following steps: S1, selecting a polytetrafluoroethylene microporous membrane for industrial dust removal as a receiving bottom membrane, and placing it on the upper surface of a liquid spray spinning receiving mesh curtain; S2, mixing powdered Bayer red mud, polytetrafluoroethylene dispersion emulsion and polyethylene oxide solution in proportion to prepare a mixed solution; S3, stirring the prepared mixed solution at an environment of 10-30°C; S4, using the stirred mixed solution as a spinning The liquid is transferred to the liquid-jet spinning storage tank and flows through the spinneret at a certain flow rate under the pressure of the plunger; S5, the spinning liquid flowing through the spinneret is drawn out and thinned by the high-pressure airflow around the spinneret to form micro-scale fibers, so that the solvent evaporates to form a liquid-jet spinning membrane; S6, the liquid-jet spinning membrane is gathered on the surface of the polytetrafluoroethylene microporous membrane on the receiving mesh curtain to form an initial polytetrafluoroethylene composite fiber membrane; S7, the initial polytetrafluoroethylene composite fiber membrane is heat-treated to obtain the final composite fiber membrane.

[0009] Furthermore, the polytetrafluoroethylene microporous membrane selected in step S1 is attached to the upper surface of the receiving mesh curtain of the liquid jet spinning by gravity; the polytetrafluoroethylene microporous membrane has a filtration efficiency greater than 95%, a porosity greater than 85%, and a thickness of 1-10 μm.

[0010] Furthermore, in step S1, the spinneret holes are arranged vertically downward, the receiving mesh curtain is arranged horizontally, the distance between the spinneret holes and the upper surface of the receiving mesh curtain is 300-1000 mm, and the winding speed of the receiving mesh curtain is 0.1-5 m / s.

[0011] Furthermore, the particle diameter of the powdered Bayer red mud in step S2 is 50-300 μm, and the main metal oxide components are CaO, Fe2O3 and Al2O3; the solid content of the polytetrafluoroethylene dispersion emulsion is 30%-60%; the concentration of the polyethylene oxide solution is 5%-20%, and the molecular weight of the polyethylene oxide is 300,000-1,000,000.

[0012] Furthermore, in step S2, the mass ratio of Bayer red mud, polytetrafluoroethylene dispersion emulsion, and polyethylene oxide solution is 1:69:30 to 5:65:30.

[0013] Furthermore, in step S3, the mixed solution prepared above is stirred uniformly at 30° C. for 4 to 20 hours.

[0014] Furthermore, the pressure applied by the plunger in step S4 is 2-10 MPa.

[0015] Furthermore, in step S5, the diameter of the spinneret is 0.3~0.8mm, the pressure of the high-pressure airflow is 0.11~0.30MPa, the high-pressure airflow wraps the spinneret, and the airflow direction forms an angle of 30°~80° with the axis of the spinneret; the number of the spinnerets is 100~3000, and the diameter range of the formed microscale fibers is 120nm~500nm.

[0016] Furthermore, the thickness of the initial polytetrafluoroethylene composite fiber membrane formed in step S6 is 1.5 μm to 15 μm.

[0017] Furthermore, in step S7, the heat treatment temperature is 360° C. to 390° C., and the speed of receiving the mesh curtain is 0.1 to 5 m / s.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention proposes a method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying, which is made by the following steps: preparation of a mixed solution of Bayer red mud, polytetrafluoroethylene dispersed emulsion, and polyethylene oxide solution, stirring, liquid spraying fiberization, composite film formation, heat treatment, winding and other processes. The present invention adopts liquid spraying technology to make a micro-scale fiber membrane from a polytetrafluoroethylene dispersed emulsion containing Bayer red mud components and composite it with a polytetrafluoroethylene microporous membrane for waste incineration dust to form a polytetrafluoroethylene composite fiber membrane for desulfurization. The polytetrafluoroethylene composite fiber membrane for removing sulfur dioxide that can be prepared by this method can reduce the concentration of sulfur dioxide from >150mg / m 3 Reduce to 15 mg / m 3 The removal efficiency is higher than 90%. At the same time, the composite polytetrafluoroethylene fiber membrane is used for garbage incineration dust purification materials, which can remove micro-scale solid particles in the smoke, with a filtration efficiency of >95%, achieving the dual performance of filtering and desulfurization of garbage incineration smoke. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to the present invention. DETAILED DESCRIPTION

[0020] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0021] See Figure 1 The present invention provides a method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying, comprising the steps of: S1. Select a polytetrafluoroethylene microporous membrane for industrial dust removal as the receiving bottom membrane and place it on the upper surface of the liquid-jet spinning receiving mesh curtain; S2, mixing powdered Bayer red mud, polytetrafluoroethylene dispersion emulsion and polyethylene oxide solution in proportion to prepare a mixed solution; S3, stirring the mixed solution prepared above at 10-30°C; if the ambient temperature is lower than 10°C, heating and stirring are required; if the temperature is higher than 30°C, the PTFE particles in the PTFE dispersion emulsion will fibrillate, and the fibrils will wrap around the PTFE particles, resulting in the inability to continuously carry out the subsequent liquid jet spinning; S4. The mixed solution after stirring is transferred to the liquid-jet spinning liquid storage tank as the spinning solution, and flows through the spinneret at a certain flow rate under the pressure of the plunger; the spinneret is configured vertically downward, the receiving mesh curtain is configured horizontally, the distance between the spinneret and the upper surface of the receiving mesh curtain is 300-1000 mm, and the winding speed of the receiving mesh curtain is 0.1-5 m / s; the advantages of this configuration are: the solvent is extruded through the spinneret, and is elongated and thinned to form micro-scale fibers under the stretching action of the high-pressure airflow on both sides; the spinneret is configured downward, and the solvent can further stretch the micro-scale fibers under the action of gravity; the speed is mainly used to control the distribution uniformity of the liquid-jet spun fiber membrane; S5. The spinning solution flowing through the spinneret is elongated and thinned by the high-pressure airflow around the spinneret, forming micro-scale fibers, and the solvent (water, polyethylene oxide) is volatilized to form a liquid-jet-spun membrane. The solvent volatilization has a significant impact on the structural uniformity of the liquid-jet-spun fiber membrane. For the target composite membrane, if the solvent cannot be evaporated in time, the fiber stacking density in the liquid-jet-spun fiber membrane will be high, resulting in increased filtration resistance. S6, collecting the liquid-jet-spun membrane formed above on the surface of the polytetrafluoroethylene microporous membrane on the receiving mesh curtain to form an initial polytetrafluoroethylene composite fiber membrane; S7. Heat-treating the initial polytetrafluoroethylene composite fiber membrane to obtain a final composite fiber membrane.

[0022] The liquid-jet-spinning membrane produced by this method is evenly distributed on the PTFE microporous base membrane, preventing the liquid-jet jet from rupturing the membrane. During industrial dust removal, dust-laden gas first contacts the PTFE microporous base membrane and then the liquid-jet-spinning membrane. The PTFE microporous membrane intercepts microscale solid particles in the dust-laden gas and has no catalytic effect on sulfide gases. Sulfur-containing gases then pass through the PTFE microporous base membrane and contact the liquid-jet-spinning membrane (catalytic membrane), where they are degraded by the Bayer red mud catalyst. The efficiency of the catalyst directly determines the removal efficiency of sulfur-containing gases. In actual industrial dust filtration, flue gas velocities are often less than 1 m / min, allowing sufficient contact between the sulfur-containing gas and the catalyst on the liquid-jet-spinning fiber membrane for degradation.

[0023] The composite membrane prepared by the present invention can intercept micro-scale solid particles in dust-containing gas, and the liquid-sprayed fiber membrane can catalytically degrade sulfur-containing gas in the dust-containing gas, thereby achieving dual functions.

[0024] The solution concentration and ratio control will affect the continuous formation of the fiber membrane and the fiber diameter of the liquid-jet spinning. Preferably, the solid content of the polytetrafluoroethylene dispersion emulsion is 30%~60%; the concentration of the polyethylene oxide solution in the step S2 is 5%~20%, and the molecular weight of the polyethylene oxide is 300,000~1 million; the mass ratio of Bayer red mud, polytetrafluoroethylene dispersion emulsion, and polyethylene oxide solution in the step S2 is 1:69:30~5:65:30.

[0025] In order to ensure the stability of the liquid-jet spun fiber membrane structure and avoid problems such as holes and uneven thickness, preferably, in step S5, the spinneret aperture is 0.3-0.8 mm, the pressure of the high-pressure airflow is 0.11-0.30 MPa, the high-pressure airflow wraps around the spinneret, and the airflow direction forms an angle of 30°-80° with the spinneret axis; the number of the spinnerets is 100-3000, and the diameter of the formed micro-scale fibers ranges from 120 nm to 500 nm.

[0026] In addition, the temperature is controlled to improve the structural stability of the liquid-jet spun fiber membrane after sintering. Preferably, the heat treatment temperature in step S7 is 360° C. to 390° C., and the speed of the receiving mesh curtain is 0.1 to 5 m / s.

[0027] The beneficial effects of the present invention are as follows: 1) The present invention adopts liquid spray technology to prepare a micro-scale fiber membrane containing Bayer red mud and composite it with a polytetrafluoroethylene microporous membrane, which can efficiently remove sulfur dioxide from waste incineration smoke and has the function of purifying the smoke, giving the microporous membrane used for waste incineration purification the dual performance of sulfur removal and high-efficiency filtration.

[0028] 2) The present invention provides a method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying, which has a short process flow and simple operation.

[0029] 3) The present invention provides a method for preparing a polytetrafluoroethylene composite fiber membrane for sulfur removal based on solution spraying. The prepared composite fiber membrane is used for waste incineration smoke purification and can reduce the energy consumption of removing sulfur dioxide.

[0030] Example 1 In step (1), a polytetrafluoroethylene microporous membrane with a filtration efficiency of 95%, a porosity of 85%, and a thickness of 1 μm was selected. The microporous membrane was attached to the upper surface of the liquid-jet spinning receiving screen by gravity, without any other adhesive components or treatment processes. The liquid-jet spinning holes were arranged vertically downward, the receiving screen was arranged horizontally, the spinneret holes were spaced 30 mm from the upper surface of the receiving screen, and the receiving screen was wound at a speed of 0.2 m / s.

[0031] In step (2), powdered Bayer red mud is mixed with a polytetrafluoroethylene dispersion and a polyethylene oxide solution in a certain proportion to prepare a mixed solution. The powdered Bayer red mud has a particle diameter of 60 μm, the polytetrafluoroethylene dispersion has a solids content of 40%, and the polyethylene oxide solution has a concentration of 8% and a molecular weight of 400,000. The mass ratio of Bayer red mud, polytetrafluoroethylene dispersion, and polyethylene oxide solution is 1:69:30.

[0032] In step (3), the mixed solution prepared above was stirred uniformly at 30° C. for 6 h.

[0033] Step (4) The stirred mixed liquid is transferred to the liquid jet spinning liquid storage tank. Under the pressure of the plunger, the mixed liquid flows through the spinneret at a certain flow rate; the pressure of the plunger rod is 2.

[0034] In step (5), the spinning liquid flowing through the spinneret is drawn out and thinned by the high-pressure airflow around the spinneret to form micro-scale fibers, and the solvent evaporates; the spinneret aperture in the liquid-jet spinning technology is 0.4 mm, the pressure of the high-pressure airflow is 0.12 MPa, the high-pressure airflow wraps around the spinneret, and the airflow direction forms a certain angle with the axis of the spinneret, and the angle varies within a range of 30°; the number of spinnerets is 100; and micro-scale fibers are formed with a fiber diameter of 150 nm.

[0035] Step (six) The micro-scale fibers are aggregated on the surface of the polytetrafluoroethylene microporous membrane on the receiving mesh curtain to form an initial polytetrafluoroethylene composite fiber membrane; the thickness of the initial composite fiber membrane is 2.0 μm.

[0036] Step (seven) The initial polytetrafluoroethylene composite fiber membrane is heat-treated to obtain a composite fiber membrane with a compact and stable structure; the heat treatment temperature is 380° C. and the speed is 0.2 m / s.

[0037] This method can prepare a polytetrafluoroethylene composite fiber membrane for removing sulfur dioxide, which can reduce the concentration of sulfur dioxide from 160 mg / m 3 Reduce to 15 mg / m 3 The removal efficiency is higher than 90%, and the filtration efficiency of removing micro-scale solid particles in smoke is higher than 95%.

[0038] Example 2 In step (1), a polytetrafluoroethylene microporous membrane with a filtration efficiency of 95%, a porosity of 85%, and a thickness of 1 μm was selected. The microporous membrane was attached to the upper surface of the liquid-jet spinning receiving screen by gravity, without any other adhesive components or treatment processes. The liquid-jet spinning holes were arranged vertically downward, the receiving screen was arranged horizontally, the spinneret holes were spaced 50 mm from the upper surface of the receiving screen, and the receiving screen was wound at a speed of 0.5 m / s.

[0039] In step (2), powdered Bayer red mud is mixed with a polytetrafluoroethylene dispersion and a polyethylene oxide solution in a certain proportion to prepare a mixed solution. The powdered Bayer red mud has a particle diameter of 60 μm, the polytetrafluoroethylene dispersion has a solids content of 50%, the polyethylene oxide solution has a concentration of 10%, and the polyethylene oxide has a molecular weight of 500,000. The mass ratio of Bayer red mud, polytetrafluoroethylene dispersion, and polyethylene oxide solution is 3:67:30.

[0040] In step (3), the mixed solution prepared above was stirred uniformly at 30° C. for 10 h.

[0041] Step (4) The stirred mixed liquid is transferred to the liquid jet spinning liquid storage tank. Under the pressure of the plunger, the mixed liquid flows through the spinneret at a certain flow rate; the pressure of the plunger rod is 2 MPa.

[0042] In step (5), the spinning liquid flowing through the spinneret is drawn out and thinned by the high-pressure airflow around the spinneret to form micro-scale fibers, and the solvent evaporates; the spinneret aperture in the liquid-jet spinning technology is 0.5 mm, the pressure of the high-pressure airflow is 0.12 MPa, the high-pressure airflow wraps around the spinneret, and the flow direction of the airflow forms a certain angle with the axis of the spinneret, and the angle varies within a range of 45°; the number of spinnerets is 150; micro-scale fibers are formed, and the fiber diameter is 180 nm.

[0043] Step (six) The micro-scale fibers are aggregated on the surface of the polytetrafluoroethylene microporous membrane on the receiving mesh curtain to form an initial polytetrafluoroethylene composite fiber membrane; the thickness of the initial composite fiber membrane is 3.0 μm.

[0044] Step (seven) The initial polytetrafluoroethylene composite fiber membrane is heat-treated to obtain a composite fiber membrane with a compact and stable structure; the heat treatment temperature is 390° C. and the speed is 0.5 m / s.

[0045] This method can prepare a polytetrafluoroethylene composite fiber membrane for removing sulfur dioxide, which can reduce the concentration of sulfur dioxide from 160 mg / m 3 Reduced to 13 mg / m 3 The removal efficiency is higher than 90%, and the filtration efficiency of removing micro-scale solid particles in smoke is higher than 97%.

[0046] Example 3 In step (1), a polytetrafluoroethylene microporous membrane with a filtration efficiency of 95%, a porosity of 85%, and a thickness of 1 μm was selected. The microporous membrane was attached to the upper surface of the liquid-jet spinning receiving screen by gravity, without any other adhesive components or treatment processes. The liquid-jet spinning holes were arranged vertically downward, the receiving screen was arranged horizontally, the spinneret holes were spaced 60 mm from the upper surface of the receiving screen, and the receiving screen was wound at a speed of 0.6 m / s.

[0047] In step (2), powdered Bayer red mud is mixed with a polytetrafluoroethylene dispersion and a polyethylene oxide solution in appropriate proportions to prepare a mixed solution. The powdered Bayer red mud has a particle diameter of 60 μm, the polytetrafluoroethylene dispersion has a solids content of 60%, the polyethylene oxide solution has a concentration of 12%, and the polyethylene oxide has a molecular weight of 600,000. The mass ratio of Bayer red mud, polytetrafluoroethylene dispersion, and polyethylene oxide solution is 5:65:30.

[0048] In step (3), the mixed solution prepared above was stirred uniformly at 30° C. for 15 h.

[0049] Step (4) The stirred mixed liquid is transferred to the liquid jet spinning liquid storage tank. Under the pressure of the plunger, the mixed liquid flows through the spinneret at a certain flow rate; the pressure of the plunger rod is 2 MPa.

[0050] In step (5), the spinning liquid flowing through the spinneret is drawn out and thinned by the high-pressure airflow around the spinneret to form micro-scale fibers, and the solvent evaporates; the spinneret aperture in the liquid-jet spinning technology is 0.6 mm, the pressure of the high-pressure airflow is 0.15 MPa, the high-pressure airflow wraps around the spinneret, and the flow direction of the airflow forms a certain angle with the axis of the spinneret, and the angle varies within a range of 60°; the number of spinnerets is 200; and micro-scale fibers are formed with a fiber diameter of 200 nm.

[0051] Step (six) The micro-scale fibers are aggregated on the surface of the polytetrafluoroethylene microporous membrane on the receiving mesh curtain to form an initial polytetrafluoroethylene composite fiber membrane; the thickness of the initial composite fiber membrane is 4.0 μm.

[0052] Step (seven) The initial polytetrafluoroethylene composite fiber membrane is heat-treated to obtain a composite fiber membrane with a compact and stable structure; the heat treatment temperature is 390° C. and the speed is 0.6 m / s.

[0053] This method can prepare a polytetrafluoroethylene composite fiber membrane for removing sulfur dioxide, which can reduce the concentration of sulfur dioxide from 160 mg / m 3 Reduce to 12 mg / m 3 The removal efficiency is higher than 90%, and the filtration efficiency of removing micro-scale solid particles in smoke is up to or higher than 99%.

[0054] In the sulfur dioxide removal test, the polytetrafluoroethylene composite fiber membrane prepared above was used as the raw material, a binder was added, and a fiber felt product was formed by pressurization. The specific test process is as follows: 1. Prepare 200mg / L sulfur dioxide gas: After precise calculation of V 二氧化硫 :V 氮气 ≈1:13; 2. Fill the quartz tube with fiber felt. The filling amount of the two groups must be consistent to ensure the same experimental conditions each time. 3. Connect the gas distribution device, tubular reactor, gas sampling device and sulfur dioxide concentration detector, check the air tightness of the device to ensure there is no gas leakage; 4. Start the tubular reactor and set the temperature to 150°C. Simultaneously start the temperature controller and thermocouple thermometer to monitor the heating process of the reactor. Once the temperature stabilizes, maintain a constant temperature. 5. Use a mass flow meter to introduce sulfur dioxide gas and high-purity nitrogen into the gas mixing tank in a certain proportion to prepare a mixed gas with an initial sulfur dioxide concentration of 200 mg / L; 6. Turn on the gas sampling device, collect the initial mixed gas sample, measure its concentration using a sulfur dioxide concentration detector, and record the data; 7. Pass the prepared mixed gas into the quartz tube filled with fiber felt at a steady flow rate. At the same time, close the valves on both sides of the reaction device and start the stopwatch to ensure that the gas stays in the quartz tube for 20 seconds. 8. After 20 seconds, open the nitrogen valve and the gas outlet valve. When the gas flows out of the quartz tube, use a sulfur dioxide concentration detector to test its sulfur dioxide concentration and record the data. 9. Repeat the above experiment and take the average of the two data; the final measured sulfur dioxide removal efficiency is 99.15%.

[0055] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying, characterized in that: The steps include: S1. Select a polytetrafluoroethylene microporous membrane for industrial dust removal as the receiving bottom membrane and place it on the upper surface of the liquid-jet spinning receiving mesh curtain; S2, mixing powdered Bayer red mud, polytetrafluoroethylene dispersion emulsion and polyethylene oxide solution in proportion to prepare a mixed solution; S3, stirring the mixed solution prepared above at 10-30°C; S4, transferring the stirred mixed solution as spinning solution to a liquid jet spinning storage tank, and allowing the mixed solution to flow through the spinneret at a certain flow rate under the pressure of a plunger; S5. The spinning solution flowing through the spinneret is drawn out and thinned by the high-pressure airflow around the spinneret to form micro-scale fibers, causing the solvent to evaporate to form a liquid-jet spinning membrane; S6, gathering the liquid-jet spun membrane on the surface of the polytetrafluoroethylene microporous membrane on the receiving mesh curtain to form an initial polytetrafluoroethylene composite fiber membrane; S7. Heat-treating the initial polytetrafluoroethylene composite fiber membrane to obtain a final composite fiber membrane.

2. The method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to claim 1, characterized in that: The polytetrafluoroethylene microporous membrane selected in step S1 is attached to the upper surface of the receiving mesh curtain of the liquid jet spinning by gravity; the polytetrafluoroethylene microporous membrane has a filtration efficiency greater than 95%, a porosity greater than 85%, and a thickness of 1-10 μm.

3. The method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to claim 1, characterized in that: In step S1, the spinneret holes are arranged vertically downward, the receiving mesh curtain is arranged horizontally, the distance between the spinneret holes and the upper surface of the receiving mesh curtain is 300-1000 mm, and the winding speed of the receiving mesh curtain is 0.1-5 m / s.

4. The method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to claim 1, characterized in that: In step S2, the particle diameter of the powdered Bayer red mud is 50-300 μm, and the main metal oxide components are CaO, Fe2O3 and Al2O3; the solid content of the polytetrafluoroethylene dispersion emulsion is 30%-60%; the concentration of the polyethylene oxide solution is 5%-20%, and the molecular weight of the polyethylene oxide is 300,000-1,000,000.

5. The method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to claim 1, characterized in that: In step S2, the mass ratio of Bayer red mud, polytetrafluoroethylene dispersion emulsion, and polyethylene oxide solution is 1:69:30 to 5:65:

30.

6. The method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to claim 1, characterized in that: In step S3, the mixed solution prepared above is stirred uniformly at 30° C. for 4 to 20 hours.

7. The method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to claim 1, characterized in that: The plunger pressurization pressure in step S4 is 2-10 MPa.

8. The method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to claim 1, characterized in that: In step S5, the diameter of the spinneret is 0.3-0.8 mm, the pressure of the high-pressure airflow is 0.11-0.30 MPa, the high-pressure airflow wraps the spinneret, and the airflow direction forms an angle of 30°-80° with the axis of the spinneret; the number of the spinnerets is 100-3000, and the diameter range of the formed microscale fibers is 120 nm-500 nm.

9. The method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to claim 1, characterized in that: The thickness of the initial polytetrafluoroethylene composite fiber membrane formed in step S6 is 1.5 μm to 15 μm.

10. The method for preparing a polytetrafluoroethylene composite fiber membrane for desulfurization based on solution spraying according to claim 1, characterized in that: In step S7, the heat treatment temperature is 360° C. to 390° C., and the speed of receiving the mesh curtain is 0.1 to 5 m / s.

Images