阅读说明：本技术 一种具有人工水通道的高通量复合纳米纤维膜的制备方法 (Preparation method of high-flux composite nanofiber membrane with artificial water channel ) 是由 吴述平 李亢悔 蔡佳伟 张侃 于 2021-07-09 设计创作，主要内容包括：本发明属于纳米功能材料和环境水处理领域,公开了一种具有人工水通道的高通量复合纳米纤维膜的制备方法。该方法以单壁碳纳米管作为人工水通道,通过静电喷雾将其负载到静电纺丝纳米纤维膜基体的表面,克服了传统过滤膜受选择性和渗透性相互制约的劣势,制备了具有高渗透通量的复合纳米纤维膜。本发明制备方法操作简单,成本低廉,绿色环保,所制备的复合纳米纤维膜具有较高的渗透通量和良好的生物可降解性,在处理工业废水领域具有较大的应用前景。(The invention belongs to the field of nano functional materials and environmental water treatment, and discloses a preparation method of a high-flux composite nanofiber membrane with an artificial water channel. According to the method, the single-walled carbon nanotube is used as an artificial water channel and is loaded on the surface of the electrostatic spinning nanofiber membrane substrate through electrostatic spraying, the disadvantage that the traditional filter membrane is mutually restricted by selectivity and permeability is overcome, and the composite nanofiber membrane with high permeation flux is prepared. The preparation method provided by the invention is simple to operate, low in cost and environment-friendly, and the prepared composite nanofiber membrane has high permeation flux and good biodegradability and has a wide application prospect in the field of industrial wastewater treatment.)

1. A preparation method of a high-flux composite nanofiber membrane with an artificial water channel is characterized by comprising the following steps:

(1) dissolving a biopolymer A in a proper solvent A to obtain a uniform solution A; dissolving the synthetic polymer B in deionized water to obtain a uniform solution B; preparing the solution A and the solution B into a mixed solution according to a certain proportion to obtain an electrostatic spinning solution;

(2) injecting the electrostatic spinning solution obtained in the step (1) into an injector, giving the injector a certain propelling speed through an automatic liquid supply pump, applying a high-voltage electric field between a receiving roller and a needle head, controlling the distance between the needle head and a receiving device, and spinning through electrostatic spinning equipment to obtain a nanofiber membrane matrix;

(3) dissolving chitosan in dilute acetic acid solution, and mixing with polyvinylpyrrolidone water solution according to a certain proportion to obtain uniform solution C; adding a proper amount of carbon nano tubes into the solution C, and carrying out ultrasonic treatment for a certain time until the carbon nano tubes are uniformly dispersed to obtain an electrostatic spraying solution;

(4) and (3) injecting the electrostatic spraying solution obtained in the step (3) into an injector, giving the injector a certain propelling speed through an automatic liquid supply pump, applying a high-voltage electric field between a receiving roller and a needle head, controlling the distance between the needle head and a receiving device, spraying on the nanofiber membrane matrix prepared in the step (2) through electrostatic spinning equipment to obtain the high-flux nanofiber membrane with an artificial water channel, placing the nanofiber membrane in a drying box after spraying is finished, and crosslinking through glutaraldehyde steam.

2. The preparation method according to claim 1, wherein in the step (1), the biopolymer A is one of chitosan, cellulose acetate, carboxymethyl cellulose and sodium alginate, the solvent A is one or more of acetic acid, N-dimethylformamide and deionized water, and the solute in the solution A accounts for 2-5% by mass; the synthetic polymer B is one or more of polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide and polyimide, and the solute in the solution B accounts for 5-10% by mass; the mass ratio of the solution A to the solution B is 1: 9-5: 5.

3. the preparation method according to claim 1, wherein in the step (2), the electrostatic spinning process parameters are as follows: the voltage is 20-24 kV, the receiving distance is 8-10 cm, and the propelling speed is 0.6-0.9 mL/h.

4. The production method according to claim 1, wherein, in the step (3),

in the dilute acetic acid solution of chitosan, the mass fraction of chitosan is 1-3%, the concentration of dilute acetic acid solution is 3%,

in the polyvinylpyrrolidone aqueous solution, the mass fraction of the polyvinylpyrrolidone is 8-12%,

the mixing mass ratio of the dilute acetic acid solution of chitosan to the polyvinylpyrrolidone aqueous solution is 1: 3-1: 9;

in the solution C, the addition amount of the carbon nano tube is 0.1-0.5 wt%, and the ultrasonic time is 2 h.

5. The preparation method according to claim 1, wherein in the step (4), the electrostatic spraying process parameters are as follows: the voltage is 15-18 kV, the receiving distance is 6-8 cm, and the propelling speed is 0.3-0.6 mL/h.

6. Use of the high-flux composite nanofiber membrane with the artificial water channel, which is obtained by the preparation method of any one of claims 1-5, in adsorption separation of heavy metal ions or organic dyes in a water environment.

Technical Field

The invention belongs to the field of nano functional materials and environmental water treatment, and relates to a preparation method of a high-flux composite nanofiber membrane with an artificial water channel.

Background

With the rapid development of modern industry and agriculture, water pollution becomes one of the most serious environmental pollution problems facing human beings, most of the pollutants are difficult to biodegrade, toxic and harmful dyes, heavy metal ions and the like, which not only endanger the survival of aquatic animals and plants and destroy the self-cleaning capability and ecological balance of water bodies, but also enter human bodies through the biological amplification effect of food chains through biological enrichment and seriously endanger the health of human bodies. The membrane separation method has unique advantages in removing the industrial pollutants which are difficult to biodegrade, water molecules in the wastewater pass through the semipermeable membrane by adjusting the aperture of the semipermeable membrane, and the pollutants are difficult to pass and are intercepted, so that the wastewater is purified. The membrane separation method has the characteristics of high efficiency, easy operation, space saving, good effluent quality and the like, and is one of the most widely applied water treatment technologies. However, the membrane separation device with the highest energy efficiency still needs to consume 2-4 kW.h of energy per cubic meter of water produced at present and is far higher than a theoretical limit value (about 1 kW.h/m)³). Therefore, how to further improve the permeability and selectivity of the membrane is a main research direction of the membrane separation method.

Unfortunately, the permeability and selectivity of a separation membrane are a pair of interdependent factors (permability-selectivity traff), i.e., a separation membrane with a strong permeability is generally less selective, and vice versa. This is due to the non-uniform free volume size and pore size distribution of the membrane. At the end of the 20 th century, however, researchers have found that cell membranes have high permeability and selectivity for water molecules, since they have a special class of aquaporins on their cell membranes, each of which can be transported 10 a second, while only allowing water molecules to pass through⁹Water molecules, which provides a new idea for preparing a high-flux separation membrane. In recent years, with the development of bioscience and material science, research on bionic artificial water channels has started to rise.

The electrostatic spinning technology is one of hot spot technologies for preparing the separation membrane at present, and compared with other membrane preparation technologies, the nanofiber membrane prepared by the electrostatic spinning technology has higher specific surface area, denser molecular channels and more uniform pore size distribution. And the reinforcing material can be conveniently and uniformly dispersed in the matrix material by the electrostatic spraying technology, which provides technical support for preparing the high-flux nanofiber membrane with the artificial water channel.

Carbon nanotubes have been the focus of research since their discovery due to their unique structures and properties. Researchers find that the motion state of water molecules in the carbon nano tube pore canal presents similar characteristics to those in aquaporin, and the transmission speed of the water molecules is several orders of magnitude higher than that of the water molecules in other medium pore canals. Therefore, the carbon nanotube has a condition to become an artificial water channel. However, the carbon nanotubes are very easy to agglomerate in the polymer matrix, and this disadvantage greatly limits the application of the carbon nanotubes. Polyvinylpyrrolidone, a relatively common surfactant, has been shown to disperse carbon nanotubes well, and by combining with electrostatic spray techniques, the dispersibility of carbon nanotubes can be further improved. Meanwhile, the carbon nano tube is used as a reinforcing material, and the mechanical property of the nanofiber membrane can be improved.

Disclosure of Invention

In view of the above analysis, the present invention provides a method for preparing a composite nanofiber membrane having a high permeation flux, in view of the disadvantage that the conventional filtration membrane is mutually restricted in selectivity and permeability. The method is convenient and rapid, energy-saving and environment-friendly, and the prepared composite nanofiber membrane has high permeation flux and good biodegradability and has a wide application prospect in the field of industrial wastewater treatment.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a preparation method of a high-flux nanofiber membrane with an artificial water channel comprises the following steps:

(1) dissolving a biopolymer A in a proper solvent A to obtain a uniform solution A; dissolving the synthetic polymer B in deionized water to obtain a uniform solution B; preparing the solution A and the solution B into a mixed solution according to a certain proportion to obtain an electrostatic spinning solution;

(2) injecting the electrostatic spinning solution obtained in the step (1) into an injector, giving the injector a certain propelling speed through an automatic liquid supply pump, applying a high-voltage electric field between a receiving roller and a needle head, controlling the distance between the needle head and a receiving device, and spinning through electrostatic spinning equipment to obtain a nanofiber membrane matrix;

(3) dissolving chitosan in dilute acetic acid solution, and mixing with polyvinylpyrrolidone water solution according to a certain proportion to obtain uniform solution C; adding a proper amount of carbon nano tubes into the solution C, and carrying out ultrasonic treatment for a certain time until the carbon nano tubes are uniformly dispersed to obtain an electrostatic spraying solution;

(4) and (3) injecting the electrostatic spraying solution obtained in the step (3) into an injector, giving the injector a certain propelling speed through an automatic liquid supply pump, applying a high-voltage electric field between a receiving roller and a needle head, controlling the distance between the needle head and a receiving device, spraying on the nanofiber membrane matrix prepared in the step (2) through electrostatic spinning equipment to obtain the high-flux nanofiber membrane with an artificial water channel, placing the nanofiber membrane in a drying box after spraying is finished, and crosslinking through glutaraldehyde steam.

In the step (1), the biopolymer A is one of chitosan, cellulose acetate, carboxymethyl cellulose and sodium alginate, the solvent A is one or more of acetic acid, N-dimethylformamide and deionized water, and the solute in the solution A accounts for 2-5% by mass; the synthetic polymer B is one or more of polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide and polyimide, and the solute in the solution B accounts for 5-10% by mass; the mass ratio of the solution A to the solution B is 1: 9-5: 5.

further, in the step (2), the electrostatic spinning process parameters are as follows: the voltage is 20-24 kV, the receiving distance is 8-10 cm, and the propelling speed is 0.6-0.9 mL/h.

Further, in the step (3),

in a dilute acetic acid solution of chitosan, the mass fraction of the chitosan is 1-3%, the concentration of the dilute acetic acid solution is 3%,

in the polyvinylpyrrolidone aqueous solution, the mass fraction of the polyvinylpyrrolidone is 8-12%,

the mixing mass ratio of the dilute acetic acid solution of chitosan to the polyvinylpyrrolidone aqueous solution is 1: 3-1: 9;

in the solution C, the addition amount of the carbon nano tube is 0.1-0.5 wt%, and the ultrasonic time is 2 h.

Further, in the step (4), the electrostatic spraying process parameters are as follows: the voltage is 15-18 kV, the receiving distance is 6-8 cm, and the propelling speed is 0.3-0.6 mL/h.

According to the bio-based nanofiber ultrafiltration membrane prepared by the method, the carbon nano tube plays a role of an artificial water channel, the permeation flux is greatly improved while the selectivity is ensured, the defect that the traditional filtration membrane is mutually restricted by the selectivity and the permeability is overcome, and the bio-based nanofiber ultrafiltration membrane is suitable for adsorption separation of heavy metal ions or organic dyes in a water environment.

The invention has the beneficial effects that:

1) the invention combines electrostatic spinning and electrostatic spraying, adopts low-toxicity and biodegradable medicines and reagents in the whole production process, does not generate secondary pollution, is green and environment-friendly, has low energy consumption, convenient operation and low cost, and is easy for large-scale production.

2) The nanofiber membrane prepared by the method disclosed by the invention is large in permeation flux, high in porosity and uniform in pore size distribution, and has a wide application prospect in the field of industrial wastewater treatment.

Drawings

FIG. 1 is an SEM image of an electrospun matrix of example 1;

FIG. 2 is an SEM image of an electrospray coating of example 1;

FIG. 3 is a TEM image of single-walled carbon nanotubes of example 1;

FIG. 4 is an SEM image of a cross-section of the composite membrane of example 1.

Detailed Description

The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.

Example 1

Weighing 3g of chitosan, dissolving the chitosan in 97g of acetic acid with the mass fraction of 90%, and stirring for 4 hours by magnetic force to obtain a chitosan solution with the mass fraction of 3% after complete dissolution. Weighing 10g of polyvinylpyrrolidone (PVP) and 5g of polyvinyl alcohol (PVA), dissolving in 85g of deionized water, magnetically stirring for 4h at 90 ℃, and completely dissolving to obtain a PVP/PVA solution with the mass fraction of 15%. The chitosan solution, PVP/PVA solution were mixed at a ratio of 2: 8, preparing a mixed solution, and uniformly mixing the mixed solution by using a vortex mixer to obtain the electrostatic spinning solution.

Injecting the electrostatic spinning solution into an injector, controlling the injection propelling speed by an automatic liquid supply pump, setting the voltage to be 20kV, the injection speed to be 0.6mL/h and the receiving distance to be 8cm, and carrying out electrostatic spinning to prepare the nanofiber membrane.

12g PVP was weighed, dissolved in 88g deionized water, and mixed with 3 wt% chitosan solution in a 3: 1, adding 0.1 wt% of single-walled carbon nanotubes after magnetic stirring for 1 hour, and dispersing the carbon nanotubes uniformly by ultrasonic treatment for 2 hours to obtain an electrostatic spraying solution.

Injecting the electrostatic spraying solution into an injector, controlling the injection propelling speed by an automatic liquid supply pump, setting the voltage to be 16kV, controlling the injection propelling speed to be 0.4mL/h and the receiving distance to be 6cm, carrying out electrostatic spraying, taking the obtained composite nanofiber membrane off the receiving device after 2.5h, moving the composite nanofiber membrane into a drying oven containing 25% glutaraldehyde aqueous solution, preserving the heat for 48h at 50 ℃, and carrying out crosslinking by glutaraldehyde vapor.

Example 2

Weighing 5g of carboxymethyl cellulose, dissolving the carboxymethyl cellulose in 95g of deionized water, magnetically stirring for 4 hours, and obtaining a carboxymethyl cellulose solution with the mass fraction of 5% after complete dissolution. Weighing 10g of polyvinyl alcohol (PVA), dissolving in 90g of deionized water, and magnetically stirring for 4h at 90 ℃ to obtain a PVA solution with the mass fraction of 10% after complete dissolution. Mixing a carboxymethyl fiber solution and a PVA solution in a ratio of 2: 8, preparing a mixed solution, and uniformly mixing the mixed solution by using a vortex mixer to obtain the electrostatic spinning solution.

Injecting the electrostatic spinning solution into an injector, controlling the injection propelling speed by an automatic liquid supply pump, setting the voltage to be 23kV, the injection speed to be 0.9mL/h and the receiving distance to be 8cm, and carrying out electrostatic spinning to prepare the nanofiber membrane.

10g PVP was weighed, dissolved in 90g deionized water, and mixed with 3 wt% chitosan solution at a ratio of 5: 1, adding 0.3 wt% of single-walled carbon nanotubes after magnetic stirring for 1 hour, and dispersing the carbon nanotubes uniformly by ultrasonic treatment for 2 hours to obtain an electrostatic spraying solution.

Injecting the electrostatic spraying solution into an injector, controlling the injection propelling speed by an automatic liquid supply pump, setting the voltage to be 16kV, controlling the injection propelling speed to be 0.4mL/h and the receiving distance to be 6cm, carrying out electrostatic spraying, taking the obtained composite nanofiber membrane off the receiving device after 2.5h, moving the composite nanofiber membrane into a drying oven containing 25% glutaraldehyde aqueous solution, preserving the heat for 48h at 50 ℃, and carrying out crosslinking by glutaraldehyde vapor.

Example 3

Weighing 5g of sodium alginate, dissolving the sodium alginate in 95g of deionized water, and stirring the mixture for 4 hours by magnetic force to obtain a sodium alginate solution with the mass fraction of 5 percent after the sodium alginate solution is completely dissolved. Weighing 8g of polyvinyl alcohol (PVA), dissolving in 92g of deionized water, and magnetically stirring for 4h at 90 ℃ to obtain a PVA solution with the mass fraction of 8% after complete dissolution. Mixing a sodium alginate solution and a PVA solution in a ratio of 1: 9, preparing a mixed solution, and uniformly mixing the mixed solution by using a vortex mixer to obtain the electrostatic spinning solution.

Injecting the electrostatic spinning solution into an injector, controlling the injection propelling speed by an automatic liquid supply pump, setting the voltage to be 20kV, the injection speed to be 0.6mL/h and the receiving distance to be 10cm, and carrying out electrostatic spinning to prepare the nanofiber membrane.

10g of PVP was weighed, dissolved in 90g of deionized water and mixed with 1 wt% chitosan solution in a ratio of 9: 1, adding 0.3 wt% of single-walled carbon nanotubes after magnetic stirring for 1 hour, and dispersing the carbon nanotubes uniformly by ultrasonic treatment for 2 hours to obtain an electrostatic spraying solution.

Injecting the electrostatic spraying solution into an injector, controlling the injection propelling speed by an automatic liquid supply pump, setting the voltage to be 18kV, controlling the injection propelling speed to be 0.3mL/h and the receiving distance to be 6cm, carrying out electrostatic spraying, taking the obtained composite nanofiber membrane off the receiving device after 2.5h, moving the composite nanofiber membrane into a drying oven containing 25% glutaraldehyde aqueous solution, preserving the heat for 48h at 50 ℃, and carrying out crosslinking by glutaraldehyde vapor.

Example 4

Weighing 3g of chitosan, dissolving the chitosan in 97g of acetic acid with the mass fraction of 90%, and stirring for 4 hours by magnetic force to obtain a chitosan solution with the mass fraction of 3% after complete dissolution. Weighing 8g of polyvinylpyrrolidone (PVP) and 8g of polyvinyl alcohol (PVA), dissolving in 84g of deionized water, magnetically stirring for 4 hours at 90 ℃, and completely dissolving to obtain a PVP/PVA solution with the mass fraction of 16%. The chitosan solution, PVP/PVA solution were mixed at 3: 7, preparing a mixed solution, and uniformly mixing the mixed solution by using a vortex mixer to obtain the electrostatic spinning solution.

Injecting the electrostatic spinning solution into an injector, controlling the injection propelling speed by an automatic liquid supply pump, setting the voltage to be 23kV, the injection speed to be 0.8mL/h and the receiving distance to be 10cm, and carrying out electrostatic spinning to prepare the nanofiber membrane.

12g PVP was weighed, dissolved in 88g deionized water, and mixed with 1 wt% chitosan solution at a ratio of 5: 1, adding 0.3 wt% of single-walled carbon nanotubes after magnetic stirring for 1 hour, and dispersing the carbon nanotubes uniformly by ultrasonic treatment for 2 hours to obtain an electrostatic spraying solution.

Injecting the electrostatic spraying solution into an injector, controlling the injection propelling speed by an automatic liquid supply pump, setting the voltage to be 18kV, controlling the injection propelling speed to be 0.3mL/h and the receiving distance to be 6cm, carrying out electrostatic spraying, taking the obtained composite nanofiber membrane off the receiving device after 2.5h, moving the composite nanofiber membrane into a drying oven containing 25% glutaraldehyde aqueous solution, preserving the heat for 48h at 50 ℃, and carrying out crosslinking by glutaraldehyde vapor.

FIGS. 1 to 4 can illustrate that the nanofiber matrix prepared by the method has uniform fiber diameter and dense mesh distribution, and the porosity of the nanofiber membrane is improved; in the electrostatic spray coating, the shapes of the small balls and the single-walled carbon nano tubes are regular and the distribution is uniform.

Table 1 the nanofiber composite membrane of example 1 was tested for filtration performance by a reduced pressure filtration method, and the results show that the pure water flux and the ion filtration flux of the nanofiber composite membrane prepared according to the present invention are higher than those of a common commercial PVDF ultrafiltration membrane, and 50mg/L of Cu was used for the filtration performance of the nanofiber composite membrane of example 1²⁺Has a filtration efficiency of 87.02%. In conclusion, the invention combines electrostatic spinning and electrostatic spraying, and overcomes the defects of the traditional filtrationThe membrane has the disadvantage of mutual restriction of selectivity and permeability, and the composite nanofiber membrane with high permeation flux is prepared. The preparation method is simple, convenient and quick, has low cost, is green and environment-friendly, has good biodegradability, and has a wide application prospect in the field of industrial wastewater treatment.

Table 1 compares the reduced pressure filtration effect of example 1 with a commercial PVDF membrane.