High-intensity ternary gradient structure PVDF tubular ultrafilter membrane and preparation method

[0034] Example 1

[0035] (1) Pour the PVDF powder with a particle size of 200 meshes into a stainless steel tubular mold with an inner tube and an outer tube, and control the thickness of the support layer to be 2mm by adjusting the gap between the inner diameter of the outer tube and the outer diameter of the inner tube. Under 10MPa pressure conditions and High-temperature sintering at 180°C for 1 hour, cooling to room temperature at a rate of 10°C/min, and exiting the mold to form a support layer tubular prefabricated body with a one-layer structure.

[0036](2) Pour the PVDF powder with a particle size of 600 meshes into the transition layer sintering mold. The transition layer sintering mold is based on the inner layer of the support layer tubular prefabricated body as the outer layer of the transition layer, and uses a stainless steel tube with an outer diameter smaller than the tubular prefabricated body As the inner tube mold for transition layer sintering, adjust the difference between the outer diameter of the inner tube mold and the inner diameter of the tubular preform to control the thickness of the transition layer to 20mm, and sinter at a high temperature of 10MPa and 180°C for 1h at a temperature of 10°C/min The speed is cooled to room temperature, and the mold is withdrawn to form a binary PVDF tubular body with a binary gradient structure.

[0037] (3) High-purity nano-Al 2 o 3 The micro-particle aggregates are vacuum-dried, and ultrasonically dispersed with ethanol as the dispersing solvent. Under the condition of 60°C, the silane coupling agent 2-cyanoethyltriethoxysilane is used for magnetic stirring, reflux, and centrifugal separation. 2 o 3 The surface of inorganic nanoparticles was introduced with 2-cyanoethyltriethoxysilane, and then acidified with acetic acid at a constant temperature of 65 °C to obtain functionalized Al 2 o 3 Nanoparticles; using a plasma treatment device, at a power of 40W, with an air flow of 20cm 3 ·s -1 , process the PVDF powder material at a distance of 40cm for 20s to obtain modified PVDF with hydroxyl groups introduced into the surface. Then functionalized Al according to the mass ratio 2 o 3 Nanoparticles: Modified PVDF:DMF=5:20:75 ratio, functionalized Al 2 o 3 The nanoparticles and the modified PVDF material were fully mixed, added to the dimethylformamide (DMF) solvent, the oil bath was heated to 180 ° C, stirred until fully uniform, and kept for 3 hours to make the functionalized Al 2 o 3 The carboxyl groups on the surface of the nanoparticles undergo a condensation reaction with the hydroxyl groups on the surface of the modified PVDF to fully escape the bubbles and obtain functionalized Al with a concentration of 25%. 2 o 3 /PVDF casting solution.

[0038] (4) With the binary PVDF tubular body of step (2) as the base film, the functionalized Al of step (3) is adopted 2 o 3 /PVDF casting liquid is coated on the inner surface of the base film to form a film by the spin coating method to form a separation layer; when coating the film, the film is applied from the bottom to the top, the scraping speed is set to 10 m/min, and the coating temperature is 130 °C; After coating, the tubular body was solidified in a water bath at 20° C., soaked in 50% ethanol aqueous solution for 40 h, and dried to obtain the high-strength ternary gradient structure PVDF tubular ultrafiltration membrane.

[0039] Example 2

[0040] (1) Pour the PVDF powder with a particle size of 200 meshes into a stainless steel tubular mold with an inner tube and an outer tube, and control the thickness of the support layer to be 2mm by adjusting the gap between the inner diameter of the outer tube and the outer diameter of the inner tube. Under 10MPa pressure conditions and High-temperature sintering at 180°C for 1 hour, cooling to room temperature at a rate of 10°C/min, and exiting the mold to form a support layer tubular prefabricated body with a one-layer structure.

[0041] (2) Pour the PVDF powder into the transition layer sintering mold with a particle size of 400 meshes. The transition layer sintering mold is based on the inner layer of the support layer tubular prefabricated body as the outer layer of the transition layer, and the outer diameter is less than the stainless steel tube of the tubular prefabricated body As the inner tube mold for transition layer sintering, adjust the difference between the outer diameter of the inner tube mold and the inner diameter of the tubular preform to control the thickness of the transition layer to 20mm, and sinter at a high temperature of 10MPa and 180°C for 1h at a temperature of 10°C/min The speed is cooled to room temperature, and the mold is withdrawn to form a binary PVDF tubular body with a binary gradient structure.

[0042] (3) High-purity nano-Al 2 o 3 The micro-particle aggregates are vacuum-dried, and ultrasonically dispersed with ethanol as the dispersing solvent. Under the condition of 60°C, the silane coupling agent 2-cyanoethyltriethoxysilane is used for magnetic stirring, reflux, and centrifugal separation. 2 o 3 The surface of inorganic nanoparticles was introduced with 2-cyanoethyltriethoxysilane, and then acidified with acetic acid at a constant temperature of 65 °C to obtain functionalized Al 2 o 3 Nanoparticles; using a plasma treatment device, at a power of 40W, with an air flow of 20cm 3 ·s -1 , process the PVDF powder material at a distance of 40cm for 20s to obtain modified PVDF with hydroxyl groups introduced into the surface. Then functionalized Al according to the mass ratio 2 o 3 Nanoparticles: Modified PVDF:DMF=5:20:75 ratio, functionalized Al 2 o 3 The nanoparticles and the modified PVDF material were fully mixed, added to the dimethylformamide (DMF) solvent, the oil bath was heated to 180 ° C, stirred until fully uniform, and kept for 3 hours to make the functionalized Al 2 o 3 The carboxyl groups on the surface of the nanoparticles undergo a condensation reaction with the hydroxyl groups on the surface of the modified PVDF to fully escape the bubbles and obtain functionalized Al with a concentration of 25%. 2 o 3 /PVDF casting solution.

[0043] (4) With the binary PVDF tubular body of step (2) as the base film, the functionalized Al of step (3) is adopted 2 o 3 /PVDF cast film liquid is coated on the inner surface of the base film to form a film by spin coating to form a separation layer; when coating the film, apply the film from bottom to top, set the scraping speed to 20 m/min, and the coating temperature to 130°C; After coating, the tubular body was solidified in a water bath at 20° C., soaked in 50% ethanol aqueous solution for 40 h, and dried to obtain the high-strength ternary gradient structure PVDF tubular ultrafiltration membrane.

[0044] Example 3

[0045] (1) Pour the PVDF powder with a particle size of 100 mesh into a stainless steel tubular mold with an inner tube and an outer tube, and control the thickness of the support layer to be 2mm by adjusting the gap between the inner diameter of the outer tube and the outer diameter of the inner tube. Under 10MPa pressure conditions and High-temperature sintering at 180°C for 1 hour, cooling to room temperature at a rate of 10°C/min, and exiting the mold to form a support layer tubular prefabricated body with a one-layer structure.

[0046] (2) Pour the PVDF powder into the transition layer sintering mold with a particle size of 400 meshes. The transition layer sintering mold is based on the inner layer of the support layer tubular prefabricated body as the outer layer of the transition layer, and the outer diameter is less than the stainless steel tube of the tubular prefabricated body As the inner tube mold for transition layer sintering, adjust the difference between the outer diameter of the inner tube mold and the inner diameter of the tubular preform to control the thickness of the transition layer to 20mm, and sinter at a high temperature of 10MPa and 180°C for 1h at a temperature of 10°C/min The speed is cooled to room temperature, and the mold is withdrawn to form a binary PVDF tubular body with a binary gradient structure.

[0047] (3) High-purity nano-Al 2 o 3 The micro-particle aggregates are vacuum-dried, and ultrasonically dispersed with ethanol as the dispersing solvent. Under the condition of 60°C, the silane coupling agent 2-cyanoethyltriethoxysilane is used for magnetic stirring, reflux, and centrifugal separation. 2 o 3 The surface of inorganic nanoparticles was introduced with 2-cyanoethyltriethoxysilane, and then acidified with acetic acid at a constant temperature of 65 °C to obtain functionalized Al 2 o 3 Nanoparticles; using a plasma treatment device, at a power of 40W, with an air flow of 20cm 3 ·s -1 , process the PVDF powder material at a distance of 40cm for 20s to obtain modified PVDF with hydroxyl groups introduced into the surface. Then functionalized Al according to the mass ratio 2 o 3 Nanoparticles: Modified PVDF:DMF=5:20:75 ratio, functionalized Al 2 o 3 The nanoparticles and the modified PVDF material were fully mixed, added to the dimethylformamide (DMF) solvent, the oil bath was heated to 180 ° C, stirred until fully uniform, and kept for 3 hours to make the functionalized Al 2 o 3 The carboxyl groups on the surface of the nanoparticles undergo a condensation reaction with the hydroxyl groups on the surface of the modified PVDF to fully escape the bubbles and obtain functionalized Al with a concentration of 25%. 2 o 3 /PVDF casting solution.

[0048] (4) With the binary PVDF tubular body of step (2) as the base film, the functionalized Al of step (3) is adopted 2 o 3 /PVDF cast film liquid is coated on the inner surface of the base film to form a film by spin coating to form a separation layer; when coating the film, apply the film from bottom to top, set the scraping speed to 20 m/min, and the coating temperature to 130°C; After coating, the tubular body was solidified in a water bath at 20° C., soaked in 50% ethanol aqueous solution for 40 h, and dried to obtain the high-strength ternary gradient structure PVDF tubular ultrafiltration membrane.