Preparation method of pore size-adjustable high-flux nanofiber composite ultra-filtration membrane

A nanofiber membrane and nanofiber technology, applied in the field of ultrafiltration membranes, can solve the problems of poor mechanical properties of membranes, intolerance to shear force, etc., and achieve the effects of high membrane stability, long service life, and improved mechanical properties.

Inactive Publication Date: 2016-10-12

上海洁晟环保科技有限公司

4 Cites 15 Cited by

AI-Extracted Technical Summary

Problems solved by technology

However, nanofiber membranes also have some problems in industrial production and practical industrial applications. For example, the filter layer of nanof...

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Abstract

The invention is a method for preparing a high-throughput nanofiber composite ultrafiltration membrane with adjustable pore size, which is characterized in that: the ultrafiltration membrane uses non-woven fabric as a support layer and a polymer nanofiber layer as a base layer 1. The pore size can be adjusted and the high flux nanofiber composite ultrafiltration membrane is composed of natural cellulose nanofibers as a gel layer. The present invention combines electrospinning technology and uniform glue coating method, adopts thermally cross-linked polyacrylic acid/polyvinyl alcohol to increase the strength of the film, and adjusts the coating amount and baking conditions of cellulose nanofibers, which can be adjusted according to actual application needs Nanofiber composite ultrafiltration membranes with different pore sizes were prepared. It has been determined that the pore size of the ultrafiltration membrane prepared by the method of the present invention can be adjusted to 5-100 nm, and the pure water permeation flux of the corresponding membrane is 80-2000 L/h m under the working pressure of 0.2 MPa. ² .

Application Domain

MembranesUltrafiltration +2

Technology Topic

UltrafiltrationChemistry +15

Examples

Experimental program(3)

Example Embodiment

[0020] Example 1:

[0021] (1) Weigh 10g polyacrylonitrile (PAN) and dissolve it in 90g N, N-dimethylformamide (DMF) to obtain a uniform and transparent high molecular polymer spinning dope, add it to the nozzle to polymerize The ester non-woven fabric is the support layer for electrospinning. The basic parameters of electrospinning are: voltage 15kV, nozzle aperture 0.5mm, spinning dope flow rate 0.002mm/s, distance from spinneret to receiving drum is 20cm, spinning The temperature of the silk environment is 35°C, and the relative humidity of the surrounding environment is 20%, and the electrospun polymer nanofiber membrane-PAN nanofiber membrane, which is composited by the polymer nanofiber membrane layer and the non-woven fabric layer, is obtained.

[0022] (2) Stir 19.9g of 0.02mol/L calcium chloride solution and 0.1g of PAA solution with molecular weight of 3000 to obtain a mixed solution with a content of 0.5% PAA, and use the PAN nanofiber membrane prepared in step (1) to make The obtained 0.5% PAA mixture is fully infiltrated.

[0023] (3) Soak 10.0g of bamboo pulp foil in 120g of 10% sodium hydroxide solution at a water bath temperature of 70℃, stir for 1.5 hours at a stirring speed of 400rpm, filter with a vacuum pump, and wash the resulting bamboo pulp with water Fiber to neutral.

[0024] Under the temperature condition of 40℃, weigh 5g alkali-treated bamboo pulp fiber and add it to a stirred tank containing TEMPO 0.001g, NaClO15g and NaBr 0.01g aqueous solution. The stirring speed is 700rpm, and 3% sodium hydroxide is added dropwise to adjust the system. When the pH value is 11.0, use a pH meter to monitor it in real time. When the pH value is constant, add 5 ml of absolute ethanol to terminate the reaction. After centrifugation at 1000 rpm, the supernatant is removed to obtain a precipitate of natural cellulose nanofibers.

[0025] (4) Disperse 0.055g of the prepared natural cellulose nanofibers in 100g of deionized water to obtain a 0.055% CNF solution of natural cellulose nanofibers. Take 9g of CNF solution and add 1g of 5% PVA solution with a molecular weight of 75000, and stir well Then, a natural cellulose nanofiber coating solution with a content of 0.5% PVA and 0.0495% CNF mixed is obtained.

[0026] (5) Place the electrospun polymer nanofiber membrane treated in step (2) on the scraping equipment, and coat the natural cellulose nanofibers prepared in step (4) with a mixture of 0.5% PVA and 0.0495% CNF Add liquid into the gap between the scraper and the surface of the polymer nanofiber membrane. Set the distance between the scraper and the surface of the polymer nanofiber membrane to 50μm, and set the moving speed of the scraper to 1cm/s. Start the motor to make the scraper The natural cellulose nanofiber coating solution on the surface of the polymer nanofiber film layer is uniformly scraped and the coating amount is 500g/m 2 After it is completely gelled and formed a gel layer of natural cellulose nanofibers, it is baked for 45 minutes at a temperature of 100°C. After drying, the obtained filtration membrane is a composite ultrafiltration membrane with adjustable pore size, a non-woven fabric as a support layer, a polymer nanofiber layer as a base layer, and a natural cellulose nanofiber as a gel layer.

[0027] The prepared ultrafiltration membrane is tested with a PEG 6000 aqueous solution with a concentration of 250ppm under a constant working pressure of 0.2MPa. The flux of the ultrafiltration membrane is 80L/h·m 2 , The rejection rate is 98%, and the corresponding ultrafiltration membrane has an average pore size of 5nm.

Example Embodiment

[0028] Example 2:

[0029] (1) Weigh 10g polyurethane (PU) and dissolve it in 90g N, N-dimethylformamide (DMF) to obtain a uniform and transparent high-molecular polymer spinning dope, and add it to the nozzle. The woven fabric is the support layer for electrospinning. The basic parameters of electrospinning are: voltage 15kV, nozzle aperture 0.5mm, spinning dope flow rate 0.002mm/s, distance from spinneret to receiving drum is 20cm, spinning environment The temperature is 35°C, the relative humidity of the surrounding environment is 20%, and the electrospun polymer nanofiber membrane-PU nanofiber membrane, which is composited by the polymer nanofiber membrane layer and the non-woven fabric layer, is obtained.

[0030] (2) Stir 19.8g 0.01mol/L magnesium chloride solution and 0.2g PAA solution with molecular weight of 2000 to obtain a 1% PAA mixed solution. Use the PU nanofiber membrane prepared in step (1) with the prepared 1 The %PAA mixture is fully infiltrated.

[0031] (3) Soak 10.0g of bamboo pulp foil in 120g of 10% sodium hydroxide solution at a water bath temperature of 70℃, stir for 1.5 hours at a stirring speed of 400rpm, filter with a vacuum pump, and wash the resulting bamboo pulp with water Fiber to neutral. Under the temperature condition of 40℃, weigh 5g alkali-treated bamboo pulp fiber and add it to a stirred tank containing TEMPO 0.001g, NaClO 15g and NaBr0.01g aqueous solution. The stirring speed is 700rpm, and 3% sodium hydroxide is added dropwise to adjust The pH of the system was at 11.0. Use a pH meter to monitor in real time. When the pH is constant, add 5ml of absolute ethanol to terminate the reaction. After centrifugation at 1000 rpm, the supernatant is removed to obtain a precipitate of natural cellulose nanofibers.

[0032] (4) Disperse 0.04g of the prepared natural cellulose nanofibers in 100g of deionized water to obtain a CNF solution of 0.04% natural cellulose nanofibers precipitates, take 9g of CNF solution and add 1g of 4% PVA solution with a molecular weight of 65000 After mixing uniformly, a natural cellulose nanofiber coating solution with a content of 0.4% PVA and 0.036% CNF is obtained.

[0033] (5) Place the electrospun polymer nanofiber membrane treated in step (2) on the scraping device, and coat the natural cellulose nanofibers prepared in step (4) with 0.4% PVA and 0.036% CNF mixed The liquid is added to the gap between the scraper and the surface of the electrospun polymer nanofiber membrane, the distance between the scraper and the electrospun polymer nanofiber membrane is 50μm, the movement speed of the scraper is set to 1cm/s, and the motor is started to make the scraper The surface of the electrospun polymer nanofiber membrane is uniformly scraped out, and the coating amount is 400g/m 2 After it is completely gelled and formed into a gel layer of natural cellulose nanofibers, it is baked. The baking time is 60min and the temperature is 120°C. After drying, the obtained filtration membrane is a composite ultrafiltration membrane with adjustable pore size, a non-woven fabric as a support layer, a polymer nanofiber layer as a base layer, and a natural cellulose nanofiber as a gel layer.

[0034] Under the constant working pressure of 0.2MPa, the pure water flux of the prepared ultrafiltration membrane is 950L/h·m 2 , Using the bubble point method, the average pore size of the corresponding ultrafiltration membrane is 50nm.

Example Embodiment

[0035] Example 3:

[0036] (1) Weigh 10g of polystyrene (PS) and dissolve it in 90g of N, N-dimethylformamide (DMF) to obtain a homogeneous and transparent high molecular polymer spinning dope, add it to the nozzle to polymerize The ester non-woven fabric is the support layer for electrospinning. The basic parameters of electrospinning are: voltage 15kV, nozzle aperture 0.5mm, spinning dope flow rate 0.002mm/s, distance from spinneret to receiving drum is 20cm, spinning The temperature of the silk environment is 35°C, and the relative humidity of the surrounding environment is 20%, and the electrospun polymer nanofiber membrane-PS nanofiber membrane, which is composited by the high molecular polymer nanofiber membrane layer and the non-woven fabric layer, is obtained.

[0037] (2) Mix 19.85g of 0.02mol/L magnesium sulfate solution and 0.15g of PAA solution with molecular weight of 1000 to obtain a 0.75% PAA mixed solution, and use the PS nanofiber membrane prepared in step (1) to prepare The 0.75% PAA mixture is fully infiltrated.

[0038] (3) Soak 10.0g of bamboo pulp foil in 120g of 10% sodium hydroxide solution at a water bath temperature of 70℃, stir for 1.5 hours at a stirring speed of 400rpm, filter with a vacuum pump, and wash the resulting bamboo pulp with water Fiber to neutral. Under the temperature condition of 40℃, weigh 5g alkali-treated bamboo pulp fiber and add it to a stirred tank containing TEMPO 0.001g, NaClO 15g and NaBr0.01g aqueous solution. The stirring speed is 700rpm, and 3% sodium hydroxide is added dropwise to adjust The pH of the system was at 11.0. Use a pH meter to monitor in real time. When the pH is constant, add 5ml of absolute ethanol to terminate the reaction. After centrifugation at 1000 rpm, the supernatant is removed to obtain a precipitate of natural cellulose nanofibers.

[0039] (4) Disperse 0.02g natural cellulose nanofibers in 100g deionized water to obtain a CNF solution of 0.02% natural cellulose nanofibers. Take 9g CNF solution and add 1g 3% PVA solution with a molecular weight of 60,000, and stir well Afterwards, a natural cellulose nanofiber coating solution with a content of 0.3% PVA and 0.018% CNF mixed is obtained.

[0040] (5) Place the electrospun polymer nanofiber membrane treated in step (2) on the scraping equipment, and coat the natural cellulose nanofibers prepared in step (4) with a mixture of 0.3% PVA and 0.018% CNF The liquid is added to the gap between the scraper and the surface of the electrospun polymer nanofiber membrane, the distance between the scraper and the electrospun polymer nanofiber membrane is 50μm, the movement speed of the scraper is set to 1cm/s, and the motor is started to make the scraper The surface of the electrospun polymer nanofiber membrane is uniformly scraped and the coating amount is 200g/m 2 After the coating is finished, the residence time is 5 minutes, and after it is completely gelled to form a gel layer of natural cellulose nanofibers, it is baked for 55 minutes at a temperature of 110°C. After drying, the obtained filtration membrane is a composite ultrafiltration membrane with adjustable pore size, a non-woven fabric as a support layer, a polymer nanofiber layer as a base layer, and a natural cellulose nanofiber as a gel layer.

[0041] When the prepared ultrafiltration membrane is at a constant working pressure of 0.2MPa, the pure water flux of the ultrafiltration membrane is 1500L/h·m 2 , Using the bubble point method, the average pore size of the corresponding ultrafiltration membrane is 90nm measured.

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PUM

Property	Measurement	Unit
Aperture size	5.0 ~ 100.0	nm
Average pore size	5.0	nm
Average pore size	50.0	nm
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine

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AI-Extracted Technical Summary

Problems solved by technology

Abstract

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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