WO2020221286A1

WO2020221286A1 - β-FEOOH/POLYACRYLONITRILE COMPOSITE NANOFIBER MEMBRANE, PREPARATION METHOD THEREFOR AND USE THEREOF

Info

Publication number: WO2020221286A1
Application number: PCT/CN2020/087725
Authority: WO
Inventors: 何毅; 张李云; 范毅; 马兰; 石恒; 李双双; 钟菲; 李振宇
Original assignee: 西南石油大学
Priority date: 2019-04-30
Filing date: 2020-04-29
Publication date: 2020-11-05
Also published as: CN110205748A; CN110205748B

Abstract

Disclosed are a β-FeOOH/polyacrylonitrile composite nanofiber membrane, a preparation method therefor and the use thereof, belonging to the technical field of materials. The method for preparing the β-FeOOH/polyacrylonitrile composite nanofiber membrane comprises the following steps: preparation of a polyacrylonitrile nanofiber membrane: preparing a polyacrylonitrile nanofiber membrane by means of electrostatic spinning; stabilization treatment: subjecting the polyacrylonitrile nanofiber membrane to a gradient heating treatment; and biomineralization treatment: formulating a mixed solution from a ferric chloride solution and hydrochloric acid at a volume ratio of 2 : 1, placing the stabilized polyacrylonitrile nanofiber membrane into the mixed solution and stirring same for 1-3 min, then reacting same at a condition of 55-65ºC for 10-14 h, and then cleaning and drying same to obtain the β-FeOOH/polyacrylonitrile composite nanofiber membrane. The fiber membrane has better stability and mechanical properties, and also has superhydrophilic-underwater superhydrophobic properties, with the adsorption efficiency thereof being high, and the membrane being recyclable.

Description

Β-FeOOH/polyacrylonitrile composite nanofiber membrane and preparation method and application thereof

Technical field

The invention belongs to the technical field of materials, and specifically relates to a β-FeOOH/polyacrylonitrile composite nanofiber membrane and a preparation method and application thereof.

Background technique

Electrospinning technology is a general method for preparing fibers ranging in diameter from micrometers to nanometers. The concept of electrospinning can be traced back to 1745. After decades of development, electrospun fibers have potential applications in many fields, such as filtration, protective textiles, drug delivery, tissue engineering, electronic and photonic equipment, sensors and Catalysis; among them, in sewage treatment, recent research is devoted to the preparation of nanofiber adsorption membranes and filtration membranes by electrospinning; membrane materials composed of nanofibers have a high specific surface area and a highly interconnected nano-scale pore structure , And the characteristics of adjustable pore structure; Compared with traditional water treatment materials, these characteristics greatly improve the separation efficiency in the oil-water separation, dye, heavy metal removal process, and reduce the separation process. Energy consumption has also avoided secondary environmental pollution, and has become a new type of sewage treatment material; the current common high-molecular polymers that can be used for electrospinning are polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, etc.

Polyacrylonitrile membranes spun from polyacrylonitrile as raw materials often have similar characteristics to most polymer membranes, such as relatively cheap price and excellent mechanical properties. However, due to the natural nature of the polymer, the polyacrylonitrile fiber membrane has poor anti-pollution ability to organic matter, and it is difficult to clean it after pollution; in addition, water pollution often comes from crude oil leakage and industrial discharge, and the wastewater itself facing the separation membrane It is a complex system, including soluble dyes, heavy metals, and insoluble organics; the environment facing the separation membrane may also be a harsh and complex environment of acids, alkalis, salts and organic reagents; existing polyacrylonitrile nanofiber membranes It is often used for oil-water separation, dye and heavy metal removal, but the polyacrylonitrile nanofiber membrane has poor anti-pollution ability and self-cleaning ability, and has poor stability in organic solvents.

Summary of the invention

The purpose of the present invention is to provide a β-FeOOH/polyacrylonitrile composite nanofiber membrane, which has good stability and mechanical properties, and has super-hydrophilic-underwater super-oleophobic properties, and its adsorption efficiency is high. Recycling is conducive to industrialized mass production.

Another object of the present invention is to provide a method for preparing β-FeOOH/polyacrylonitrile composite nanofiber membrane, which is simple and low-cost, and the prepared β-FeOOH/polyacrylonitrile composite nanofiber membrane has excellent Stability and adsorption performance.

Another object of the present invention is to provide an application of β-FeOOH/polyacrylonitrile composite nanofiber membrane in sewage treatment, which has good treatment effect and can be used repeatedly.

In order to achieve the above objective, the solution adopted by the present invention is:

The present invention provides a method for preparing a β-FeOOH/polyacrylonitrile composite nanofiber membrane, which includes the following steps:

The preparation of polyacrylonitrile nanofiber membrane: the polyacrylonitrile powder and N,N-dimethylformamide solution are mixed uniformly to make a spinning solution, and then the polyacrylonitrile nanofiber membrane is spun by an electrostatic spinning device. The ratio of polyacrylonitrile powder to N,N-dimethylformamide solution is 1-1.4g:10mL;

Stabilization treatment: the polyacrylonitrile nanofiber membrane is subjected to gradient heating treatment, and the temperature is kept at 235-240°C for 0.5-2h, at 245-250°C for 0.4-0.6h, and at 258-262°C Incubate for 0.5-2h under the conditions of, then take out and cool to room temperature to prepare stabilized polyacrylonitrile nanofiber membrane;

Biomineralization treatment: prepare a mixed solution of ferric chloride solution and hydrochloric acid at a volume ratio of 2:1, and place the stabilized polyacrylonitrile nanofiber membrane in the mixed solution and stir for 1-3 minutes, and then The reaction was carried out at 55-65°C for 10-14 hours, and then washed and dried to prepare a β-FeOOH/polyacrylonitrile composite nanofiber membrane.

The present invention provides a β-FeOOH/polyacrylonitrile composite nanofiber membrane, which is prepared by the above preparation method.

The invention proposes an application of a β-FeOOH/polyacrylonitrile composite nanofiber membrane in sewage treatment.

The invention provides a β-FeOOH/polyacrylonitrile composite nanofiber membrane and its preparation method and application. The beneficial effect is that firstly, electrospinning is used to prepare polyacrylonitrile nanofiber membrane as a substrate, and the prepared nanofiber membrane has The high specific surface area is conducive to adsorption; then, the stabilization treatment of gradient heating is carried out, so that the polyacrylonitrile undergoes cyclization, oxidation and dehydrogenation reactions in sequence, and the molecular structure of polyacrylonitrile is transformed into ladder-shaped molecules. Acrylonitrile nanofiber membrane is in a "non-melting and non-combustible" state, which enables the polymer membrane to exist stably in common strong polar organic solvents. At the same time, the polyacrylonitrile nanofiber membrane has self-supporting properties, which is compared with traditional The polyacrylonitrile nanofiber membrane improves the operability of the polyacrylonitrile nanofiber membrane, which is conducive to large-scale industrial production; on the other hand, it introduces oxygen and nitrogen functional groups to improve the hydrophilicity of the polyacrylonitrile nanofiber membrane; Finally, the biomineralization treatment is carried out. In this process, the introduced β-FeOOH nanoparticles not only improve the wettability of the nanofiber membrane, but also make the nanofiber membrane present a super-hydrophilic-underwater super-oleophobic state. The introduction of negatively charged β-FeOOH further increases the specific surface area of nanofiber membranes, and greatly improves the adsorption capacity of nanofiber membranes for dyes and heavy metal ions in sewage in sewage treatment. At the same time, the introduction of β-FeOOH makes the membrane With the properties of photocatalytic degradation, the nanofiber membrane has self-cleaning and self-repairing properties under the action of visible light, so that the polyacrylonitrile nanofiber membrane can be recycled more efficiently.

Description of the drawings

In order to explain the technical solutions of the embodiments of the present invention more clearly, the following will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore do not It should be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative work.

FIG. 1 is an SEM image of the polyacrylonitrile nanofiber membrane prepared in the preparation step of the polyacrylonitrile nanofiber membrane in Example 1 of the present invention;

2 is an SEM image of the stabilized polyacrylonitrile nanofiber membrane prepared after the stabilization treatment in Example 1 of the present invention;

Figure 3 is an SEM image of a β-FeOOH/polyacrylonitrile composite nanofiber membrane obtained in Example 1 of the present invention;

Figure 4 is a water treatment diagram of the polyacrylonitrile nanofiber membrane without any treatment in the present invention;

Fig. 5 is a water treatment diagram of the stabilized polyacrylonitrile nanofiber membrane prepared after stabilization in Example 1 of the present invention;

Figure 6 shows the polyacrylonitrile nanofiber membrane (PAN) without any treatment and the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 in a dimethylacetamide (DMAC) solution Dissolution map;

Figure 7 shows the polyacrylonitrile nanofiber membrane (PAN) without any treatment and the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 in a dimethylformamide (DFM) solution Dissolution map;

Figure 8 shows the polyacrylonitrile nanofiber membrane (PAN) without any treatment and the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 in a dimethylsulfoxide (DMSO) solution Dissolution map;

Figure 9 shows the polyacrylonitrile nanofiber membrane (PAN) without any treatment and the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 in N-methylpyrrolidone (NMP) solution Dissolution map;

Figure 10 shows the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention in dimethylacetamide (DMAC) solution, dimethylformamide (DFM) solution, and dimethyl sulfide Diagram of dissolution after 5 days in sulfone (DMSO) solution, N-methylpyrrolidone (NMP) solution, sodium chloride solution, sodium hydroxide solution and hydrochloric acid solution;

Figure 11 shows the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention in dimethylacetamide (DMAC) solution, dimethylformamide (DFM) solution, and dimethyl sulfide The test results of the contact angle of underwater oil after immersing in sulfone (DMSO) solution, N-methylpyrrolidone (NMP) solution, sodium chloride solution, sodium hydroxide solution and hydrochloric acid solution for 5 days;

FIG. 12 is a comparison diagram before and after SEM of the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention after soaking in a dimethylacetamide (DMAC) solution for 5 days;

FIG. 13 is a diagram of the test results of the contact angle of the polyacrylonitrile nanofiber membrane (PAN) without any treatment in the air;

14 is a diagram showing the contact angle test results of the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention in the air;

15 is a diagram showing the contact angle test results of the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention under water for normal oil ether, normal hexane, toluene and diesel;

FIG. 16 is a diagram showing the separation results of the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention for separating oil-water emulsions;

Figure 17 is the UV-Vis spectra of the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention before and after oil-water/dye separation;

Figure 18 is the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention to treat various oil-water emulsions such as n-oleyl ether, n-hexane, toluene, diesel, SDS at an external driving pressure of 0.2 bar /N-oleyl ether, SDS/n-hexane, SDS/toluene and SDS/diesel oil permeation flux results chart;

Figure 19 is the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention in the treatment of various oil-water emulsions such as normal oil ether, normal hexane, toluene, diesel, SDS/normal oil ether, SDS /Test results of separation efficiency of n-hexane, SDS/toluene and SDS/diesel;

FIG. 20 is a test diagram of the cycle times of the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 of the present invention in processing various oil-water emulsions such as normal oleyl ether.

Detailed ways

To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. If specific conditions are not indicated in the examples, it shall be carried out in accordance with the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used without the manufacturer's indication are all conventional products that can be purchased commercially.

The following specifically describes a β-FeOOH/polyacrylonitrile composite nanofiber membrane and its preparation method and application in an embodiment of the present invention.

The preparation method of a β-FeOOH/polyacrylonitrile composite nanofiber membrane provided by an embodiment of the present invention includes the following steps:

Preparation of polyacrylonitrile nanofiber membrane: mix polyacrylonitrile powder and N,N-dimethylformamide solution uniformly to make a spinning solution, and then spin it into a polyacrylonitrile nanofiber membrane by an electrostatic spinning device, polypropylene The ratio of nitrile powder to N,N-dimethylformamide solution is 1-1.4g:10mL.

Among them, when the temperature is low, the fluidity of the solution is likely to become low, resulting in the clogging of the spinneret. When the temperature is high, it is easy to cause the excessive volatilization of N,N-dimethylformamide in the solution, which affects The formation of polyacrylonitrile nanofiber membrane; when the voltage is low, the electric field force is too small, and the electrostatic field force cannot overcome the surface tension of the solution, cannot form a jet, and cannot prepare nanofibers. When the voltage is too high, the electrostatic spinning will not be possible. Stability is not conducive to obtaining fibers with a smooth surface and uniform diameter; when the distance between the receiving device and the spinneret is too small, the electric field force between the spinneret and the collecting device is too large, which easily leads to uneven fiber diameter. When it is too large, the splitting ability of the droplets is poor, which is not conducive to the formation of nanofibers; therefore, in order to obtain a polyacrylonitrile nanofiber membrane with a smooth surface, a uniform diameter, and a good surface morphology, the conditions for electrospinning in the embodiment of the present invention are : Spinning temperature is 30-38°C, spinning voltage is 20-25kv, receiving distance is 18-22cm, ambient humidity is 45-55%, flow rate is 0.6-1.2mL/h. Preferably, the conditions of electrospinning are: spinning temperature of 35°C, spinning voltage of 25kv, receiving distance of 20cm, ambient humidity of 50%, and flow rate of 1mL/h.

It should be noted that the spinning needle type used in the embodiment of the present invention is No. 22, but it is not limited to this, and other types of spinning needles, such as No. 18, No. 20, etc., can also be used.

Among them, the ratio of polyacrylonitrile powder to N,N-dimethylformamide solution should not be too high, too high concentration of polyacrylonitrile can easily lead to clogging of the spinneret, and it should not be too low, too low to spin into polyacrylonitrile nano For the fiber membrane, the ratio of the polyacrylonitrile powder and the N,N-dimethylformamide solution in the embodiment of the present invention is 1-1.4g:10mL.

Furthermore, the spun polyacrylonitrile nanofiber membrane is dried under vacuum conditions. The purpose of drying under vacuum is to remove the residual solvent on the polyacrylonitrile nanofiber membrane without affecting the polyacrylonitrile nanofiber membrane. The structure of the fiber membrane.

Furthermore, the drying conditions are: the drying temperature is 55-65°C, and the drying time is 10-14h. Under this drying condition, the residual solvent on the polyacrylonitrile nanofiber membrane can be fully volatilized.

It should be noted that, in the embodiment of the present invention, the molecular weight of the polyacrylonitrile powder is 150,000, and the purity of N,N-dimethylformamide is 99.9%.

Stabilization treatment: The polyacrylonitrile nanofiber membrane is subjected to a gradient heating treatment, and the temperature is kept at 235-240℃ for 0.5-2h, at 245-250℃ for 0.5-2h, and at 258-262℃ Keep it for 0.5-2h, then take it out and cool to room temperature to prepare a stabilized polyacrylonitrile nanofiber membrane.

After holding for 0.5-2h at 235-240℃, the polyacrylonitrile in the polyacrylonitrile nanofiber membrane will undergo a cyclization reaction, and at 245-250℃ for 0.5-2h, the polyacrylonitrile will undergo oxidation reaction. After holding for 0.5-2h at 258-262℃, the polyacrylonitrile will undergo dehydrogenation reaction. Through cyclization, oxidation and dehydrogenation reactions, the molecular structure of polyacrylonitrile will be transformed into ladder-shaped molecules, which improves polyacrylonitrile nanofibers. The stability of the membrane, on the one hand, makes the polyacrylonitrile nanofiber membrane have the characteristics of "non-melting and non-flammable", so that the polyacrylonitrile nanofiber membrane can be used in common strong polar organic solvents (N, N-dimethylformamide, two Methyl sulfoxide, acetone, etc.) can stably exist in the harsh and complex sewage environment of acids, alkalis, salts and organic reagents, so that sewage can be effectively treated; on the other hand, through the above Reaction, the introduction of oxygen and nitrogen functional groups can improve the hydrophilic properties of the polyacrylonitrile nanofiber membrane; at the same time, because part of the polyacrylonitrile fiber is melted at high temperature, crosslinked, linear molecules are transformed into ladder-shaped molecules, making the membrane self-supporting Compared with the traditional polyacrylonitrile nanofiber membrane, this improves the operability of the membrane, which is conducive to large-scale industrial production.

Biomineralization treatment: The ferric chloride solution and the hydrochloric acid solution are configured into a mixed solution at a volume ratio of 2:1, and the stabilized polyacrylonitrile nanofiber membrane is placed in the mixed solution and stirred for 1-3 minutes, and then heated at 55 React for 10-14 hours at -65°C, then wash and dry to prepare β-FeOOH/polyacrylonitrile composite nanofiber membrane (SPN).

After mixing the ferric chloride solution and hydrochloric acid uniformly, the stabilized polyacrylonitrile nanofibers are placed in the mixed solution and stirred, and then the stirred solution is placed at 55-65°C for 10-14 hours. It is for the reaction of ferric chloride to produce β-FeOOH under acidic conditions at 55-65℃. The reaction equation is as follows:

Fe ³⁺ +3H ₂ O→Fe(OH) ₃ +3H ⁺

Fe(OH) ₃ →β-FeOOH+H ₂ O

After the biomineralization treatment, the β-FeOOH nanoparticles introduced during this process not only improve the wettability of the membrane, but also make the membrane appear super-hydrophilic-underwater super-oleophobic state. When sewage treatment Water performance can improve water permeability, and underwater super-oleophobic performance can effectively separate water and oil. On the other hand, the introduction of negatively charged β-FeOOH can further increase the specific surface area of the membrane and increase the membrane The adsorption capacity of dyes and heavy metals in sewage; at the same time, β-FeOOH is a special semiconductor material, which is introduced on the surface of the film to make the film have the performance of photocatalytic degradation. Under visible light, the nanofiber film can remove the surface of the film. Degradation of the pollutants to achieve the problem of repairing the membrane, improving the recycling capacity of the membrane, and enabling the membrane to be recycled efficiently.

Wherein, the ferric chloride solution is prepared by dissolving ferric chloride in deionized water, and the ratio of ferric chloride to deionized water is 16-20mg:1mL. In the embodiment of the present invention, the concentration of hydrochloric acid in the hydrochloric acid solution It is 10mmol/L.

Furthermore, the drying conditions in the biomineralization treatment are: the drying temperature is 55-65°C, and the drying time is 0.2-0.4h, the purpose is to dry the cleaned water.

The invention provides a method for preparing a β-FeOOH/polyacrylonitrile composite nanofiber membrane, which is simple in method and low in cost. The prepared β-FeOOH/polyacrylonitrile composite nanofiber membrane has excellent stability and adsorption performance.

The β-FeOOH/polyacrylonitrile composite nanofiber membrane provided by the present invention is prepared by the above method. It has good stability, mechanical properties, superhydrophilic-underwater superoleophobic properties, and its adsorption efficiency High, recyclable use is conducive to industrialized mass production.

The application of a β-FeOOH/polyacrylonitrile composite nanofiber membrane in sewage treatment has good treatment effect and can be used repeatedly. In the harsh and complicated sewage environment which may be acid, alkali, salt and organic reagents, the above-mentioned β-FeOOH/polyacrylonitrile composite nanofiber membrane can exist stably, and can carry out oil-water separation, dye and heavy metal removal.

Example 1

A preparation method of β-FeOOH/polyacrylonitrile composite nanofiber membrane includes the following steps:

Preparation of polyacrylonitrile nanofiber membrane: Mix 1.2 polyacrylonitrile powder and 10mL N,N-dimethylformamide solution uniformly to make a spinning solution, and then spin it into a polyacrylonitrile nanofiber membrane through an electrostatic spinning device. Then dry under vacuum conditions, where the spinning conditions are: spinning temperature of 35°C, spinning voltage of 25kv, receiving distance of 20cm, ambient humidity of 50%, flow rate of 1mL/h, drying conditions It is: drying temperature is 60℃, drying time is 12h.

Stabilization treatment: the polyacrylonitrile nanofiber membrane is subjected to a gradient heating treatment, holding at 238°C for 0.5h, at 248°C for 0.5h, at 260°C for 0.5h, and then taken out and cooled to Stabilized polyacrylonitrile nanofibers prepared at room temperature;

Biomineralization treatment: dissolve ferric chloride in deionized water to prepare a ferric chloride solution with a concentration of 18 mg/ml, configure a hydrochloric acid solution with a concentration of 10 mmol/L, and divide the ferric chloride solution and the hydrochloric acid solution by volume The ratio of 2:1 is configured into a mixed solution, the stabilized polyacrylonitrile nanofiber membrane is placed in the mixed solution and stirred for 1 min, and then reacted at 60°C for 12 hours, and then the nanofiber membrane is taken out and carried out with deionized water for 3 The composite nanofiber membrane of β-FeOOH/polyacrylonitrile was prepared by washing once and drying at 60°C for 0.3h.

Example 2

Preparation of polyacrylonitrile nanofiber membrane: 1g polyacrylonitrile powder and 10mL N,N-dimethylformamide solution are mixed uniformly to make a spinning solution, and then spun into a polyacrylonitrile nanofiber membrane through an electrostatic spinning device. Then it is dried under vacuum conditions. The spinning conditions are as follows: spinning temperature is 30℃, spinning voltage is 20kv, receiving distance is 18cm, ambient humidity is 45%, flow rate is 0.6mL/h, drying The conditions are: the drying temperature is 55°C and the drying time is 10h.

Stabilization treatment: the polyacrylonitrile nanofiber membrane is subjected to gradient heating treatment, and it is made by keeping it at 235℃ for 2h, 245℃ for 2h, 258℃ for 2h, and then taking it out and cooling to room temperature. Stabilized polyacrylonitrile nanofibers;

Biomineralization treatment: Dissolve ferric chloride in deionized water to prepare a ferric chloride solution with a concentration of 16mg/ml, configure a hydrochloric acid solution with a concentration of 10mmol/L, and divide the ferric chloride solution and the hydrochloric acid solution by volume The ratio of 2:1 is configured into a mixed solution, the stabilized polyacrylonitrile nanofiber membrane is placed in the mixed solution and stirred for 3 minutes, and then reacted at 55°C for 10 hours, and then the nanofiber membrane is taken out and carried out with deionized water for 3 The composite nanofiber membrane of β-FeOOH/polyacrylonitrile was prepared by washing once and drying for 0.2h at 55°C.

Example 3

Preparation of polyacrylonitrile nanofiber membrane: 1.4g of polyacrylonitrile powder and 10mL N,N-dimethylformamide solution are mixed uniformly to make a spinning solution, and then spun into a polyacrylonitrile nanofiber membrane by an electrospinning device , And then dried under vacuum conditions, where the spinning conditions are: spinning temperature is 38℃, spinning voltage is 25kv, receiving distance is 22cm, ambient humidity is 55%, flow rate is 1.2mL/h, drying The conditions are: the drying temperature is 65℃, and the drying time is 14h.

Stabilization treatment: The polyacrylonitrile nanofiber membrane is subjected to gradient heating treatment, holding at 240°C for 0.8h, at 250°C for 0.8h, and at 262°C for 0.8h, then take it out and cool to Stabilized polyacrylonitrile nanofibers prepared at room temperature;

Biomineralization treatment: dissolve ferric chloride in deionized water to prepare a ferric chloride solution with a concentration of 20 mg/ml, configure a hydrochloric acid solution with a concentration of 10 mmol/L, and divide the ferric chloride solution and the hydrochloric acid solution by volume The ratio of 2:1 is configured into a mixed solution, the stabilized polyacrylonitrile nanofiber membrane is placed in the mixed solution and stirred for 3 minutes, and then reacted at 65°C for 14 hours, and then the nanofiber membrane is taken out and carried out with deionized water for 3 The composite nanofiber membrane of β-FeOOH/polyacrylonitrile was prepared by washing once and drying at 65°C for 0.4h.

Example 4

Preparation of polyacrylonitrile nanofiber membrane: 1.1g polyacrylonitrile powder and 10mL N,N-dimethylformamide solution are mixed uniformly to make a spinning solution, and then spun into a polyacrylonitrile nanofiber membrane through an electrospinning device , And then dried under vacuum conditions, where the spinning conditions are: spinning temperature is 32℃, spinning voltage is 22kv, receiving distance is 21cm, ambient humidity is 52%, flow rate is 0.8mL/h, drying The conditions are: the drying temperature is 61℃, and the drying time is 11h.

Stabilization treatment: The polyacrylonitrile nanofiber membrane is subjected to gradient heating treatment, kept at 236°C for 1.2h, at 246°C for 1.2h, at 261°C for 1.2h, and then taken out and cooled to Stabilized polyacrylonitrile nanofibers prepared at room temperature;

Biomineralization treatment: Dissolve ferric chloride in deionized water to prepare a ferric chloride solution with a concentration of 19 mg/ml, configure a hydrochloric acid solution with a concentration of 10 mmol/L, and divide the ferric chloride solution and the hydrochloric acid solution by volume The ratio of 2:1 is configured into a mixed solution, the stabilized polyacrylonitrile nanofiber membrane is placed in the mixed solution and stirred for 3 minutes, and then reacted at 60°C for 14 hours, and then the nanofiber membrane is taken out and deionized water is used for 3 The composite nanofiber membrane of β-FeOOH/polyacrylonitrile was prepared by washing once and drying for 0.4h at 60°C.

Experimental example

1. The polyacrylonitrile nanofiber membrane prepared in the preparation step of the polyacrylonitrile nanofiber membrane of Example 1 was characterized by scanning electron microscopy (SEM) (shown in Figure 1), and the stabilized one obtained after stabilization The polyacrylonitrile nanofiber membrane was characterized by SEM (shown in Figure 2), and the β-FeOOH/polyacrylonitrile composite nanofiber membrane prepared after biomineralization was characterized by SEM (shown in Figure 3). It can be seen from 1 that the prepared polyacrylonitrile nanofiber membrane has a uniform diameter and good fiber morphology; it can be seen from Figure 2 that the polyacrylonitrile nanofiber membrane is entangled, and the nanofibers are tighter, indicating that after stabilization The mechanical properties of the fiber have been improved to a certain extent; as can be seen from Figure 3, the polyacrylonitrile nanofibers have introduced a lot of β-FeOOH mineral particles after biomineralization.

2. The effect comparison chart of the polyacrylonitrile nanofiber membrane that has not undergone any treatment and the stabilized polyacrylonitrile nanofiber membrane prepared after stabilization treatment in Example 1 is clamped with a clip after passing through the aqueous solution, from the figure It can be seen in 4 that the polyacrylonitrile nanofibers that have not undergone any treatment are lifted by the aqueous solution and then shrunk into a mass. From Figure 5, it can be seen that the stabilized polyacrylonitrile nanofiber membrane prepared in Example 1 after the stabilization treatment After being lifted by the aqueous solution, the polyacrylonitrile nanofiber membrane did not shrink into a mass, but also had good flatness, indicating that the polyacrylonitrile nanofiber membrane of the present invention was stabilized and improved the water swellability and support of polyacrylonitrile. This is very necessary for the subsequent processing of polyacrylonitrile nanofiber membranes.

3. Put the polyacrylonitrile nanofiber membrane (PAN) without any treatment and the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 in a dimethylacetamide (DMAC) solution, Dissolution in dimethylformamide (DFM) solution, dimethyl sulfoxide (DMSO) solution and N-methylpyrrolidone (NMP) solution, the results are shown in Figure 6 to Figure 9. The polypropylene without any treatment Nitrile nanofiber membrane (PAN) is in dimethylacetamide (DMAC) solution, dimethylformamide (DFM) solution, dimethyl sulfoxide (DMSO) solution and N-methylpyrrolidone (NMP) solution. Dissolve after different time (1-8s), and the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 is dissolved in dimethylacetamide (DMAC) solution, dimethylformamide (DFM) Solution, dimethyl sulfoxide (DMSO) solution and N-methylpyrrolidone (NMP) solution did not dissolve after soaking for 10s, indicating that the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in the embodiment of the present invention ) Has excellent stability to organic solvents, which is a very important property for the treatment of various complex sewage (containing organic solvents).

4. Put the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 in dimethylacetamide (DMAC) solution, dimethylformamide (DFM) solution, dimethylsulfoxide ( DMSO) solution and N-methylpyrrolidone (NMP) solution, sodium chloride solution, sodium hydroxide solution and hydrochloric acid solution were soaked in the solution for 5 days to observe the dissolution phenomenon, the result is shown in Figure 10, and the underwater oil contact The results of the angle test are shown in Figure 11, and the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) and the β-FeOOH/polyacrylonitrile nanofiber film immersed in dimethylacetamide (DMAC) solution for 5 days The fiber membrane (SPF) was tested by SEM, and the results are shown in Figure 12.

It can be seen from Figure 10 that the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) is in the dimethyl acetamide (DMAC) solution, dimethyl formamide (DFM) solution, dimethyl sulfoxide ( DMSO) solution and N-methylpyrrolidone (NMP) solution, sodium chloride solution, sodium hydroxide solution and hydrochloric acid solution did not dissolve after soaking for 5 days, and it has good stability.

It can be seen from Figure 11 that there is no significant change in the contact angle before and after, which once again shows that the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) has better stability.

As can be seen from Figure 12, β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) and β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) after soaking in dimethylacetamide (DMAC) solution for 5 days There is no obvious change in the SEM image, which further shows that its stability is better.

5. The polyacrylonitrile nanofiber membrane (PAN) that has not undergone any treatment and the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 were tested for contact angle in the air. The results are shown in the figure Shown in 13-14. It can be seen from the figure that the contact angle of the polyacrylonitrile nanofiber membrane (PAN) without any treatment in the air changes little after 10 seconds, which is about 118°. The β-FeOOH/polyacrylonitrile nanofiber membrane ( SPF) After 10 seconds, the contact angle decreased from 15.8° to 0, indicating that the β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared by the present invention has better hydrophilic properties.

6. The β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 was tested for the contact angles of normal oleyl ether, normal hexane, toluene and diesel under water. The results are shown in Figure 15, which can be seen In conclusion, β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) has super-oleophobic properties under water.

7. The β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 was separated into oil-water emulsion separation. The result is shown in Figure 16. The left side is after separation and the right side is before separation. You can see The separated solution is clearer, indicating that the separation effect is better.

8. The β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 is UV-Visible spectrogram before and after oil-water/dye separation. The result is shown in Figure 17, which shows that the separation effect is better. it is good.

10. The β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 is treated with various oil-water emulsions such as n-oleyl ether, n-hexane, toluene and diesel oil at an external driving pressure of 0.2 bar for permeation. The calculation of the amount and the calculation of the permeation flux in a stable oil-in-water emulsion with surfactants such as SDS/normal oil ether, SDS/n-hexane, SDS/toluene and SDS/diesel oil, the results are shown in Figure 18. As can be seen from the figure, the permeation flux is better.

11. The β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 is used in the treatment of various oil-water emulsions such as normal oil ether, n-hexane, toluene, diesel, SDS/normal oil ether, SDS/n-hexane , SDS/toluene and SDS/diesel separation efficiency test, the results are shown in Figure 19, TOC is the total carbon content in the filtrate, because various oils are organic, the filtrate TOC is used to indicate the residual oil content in the water. It can be seen from the figure that the separation efficiency is higher, as high as 98%.

12. The number of cycles of β-FeOOH/polyacrylonitrile nanofiber membrane (SPF) prepared in Example 1 in processing various oil-water emulsions such as normal oleyl ether. The results are shown in Figure 20. The permeation flux and TOC content of the filtrate did not greatly attenuate and increase. On the one hand, it represents that the membrane has a certain degree of stability and good oil resistance performance.

In summary, the present invention provides a β-FeOOH/polyacrylonitrile composite nanofiber membrane and its preparation method and application. It has good stability, mechanical properties, and superhydrophilic-underwater superphobicity. Oil properties, high adsorption efficiency and recyclable use are conducive to large-scale industrial production. .

The foregoing descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc., made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

A preparation method of β-FeOOH/polyacrylonitrile composite nanofiber membrane, characterized in that it comprises the following steps:

The preparation of polyacrylonitrile nanofiber membrane: the polyacrylonitrile powder and N,N-dimethylformamide solution are mixed uniformly to make a spinning solution, and then the polyacrylonitrile nanofiber membrane is spun by an electrostatic spinning device. The ratio of polyacrylonitrile powder to the N,N-dimethylformamide solution is 1-1.4g:10mL;

Stabilization treatment: The polyacrylonitrile nanofiber membrane is subjected to gradient heating treatment, and the temperature is kept at 235-240℃ for 0.5-2h, at 245-250℃ for 0.5-2h, and at 258-262℃. Insulate for 0.5-2h under conditions, then take out and cool to room temperature to prepare stabilized polyacrylonitrile nanofiber membrane;

Biomineralization treatment: The ferric chloride solution and the hydrochloric acid solution are configured into a mixed solution in a ratio of 2:1 by volume, and the stabilized polyacrylonitrile nanofiber membrane is placed in the mixed solution and stirred for 1-3 minutes, then React at 55-65°C for 10-14 hours, then wash and dry to prepare β-FeOOH/polyacrylonitrile composite nanofiber membrane.
The method for preparing a β-FeOOH/polyacrylonitrile composite nanofiber membrane according to claim 1, wherein the conditions of electrospinning are: spinning temperature is 30-38°C, spinning voltage is 20-25kv , The receiving distance is 18-22cm, the ambient humidity is 45-55%, and the flow rate is 0.6-1.2mL/h.
The method for preparing β-FeOOH/polyacrylonitrile composite nanofiber membranes according to claim 2, characterized in that: the conditions of electrospinning are: spinning temperature of 35°C, spinning voltage of 25kv, and receiving distance of 20cm, ambient humidity 50%, flow rate 1mL/h.
The method for preparing β-FeOOH/polyacrylonitrile composite nanofiber membranes according to claim 1, characterized in that: in the step of preparing the polyacrylonitrile nanofiber membranes, the spun polyacrylonitrile nanofibers The film is dried under vacuum.
The method for preparing β-FeOOH/polyacrylonitrile composite nanofiber membrane according to claim 4, characterized in that the drying conditions are: drying temperature 55-65°C, drying time 10-14h .
The method for preparing β-FeOOH/polyacrylonitrile composite nanofiber membrane according to claim 1, wherein the ferric chloride solution is prepared by dissolving ferric chloride in deionized water, and The ratio of ferric chloride to the deionized water is 16-20 mg: 1 mL.
The method for preparing a β-FeOOH/polyacrylonitrile composite nanofiber membrane according to claim 1, wherein the drying conditions in the biomineralization treatment step are: the drying temperature is 55-65°C, The drying time is 0.2-0.4h.
The method for preparing a β-FeOOH/polyacrylonitrile composite nanofiber membrane according to claim 1, wherein the concentration of hydrochloric acid in the hydrochloric acid solution is 10 mmol/L.
A β-FeOOH/polyacrylonitrile composite nanofiber membrane, characterized in that it is prepared by the preparation method of the β-FeOOH/polyacrylonitrile composite nanofiber membrane according to any one of claims 1-8.
The application of the β-FeOOH/polyacrylonitrile composite nanofiber membrane in sewage treatment according to claim 9.