CN110295406A - Porous cellulose acetate composite micro/nano tunica fibrosa, centrifugal spinning preparation method and its application at heavy metal ion adsorbed aspect - Google Patents

Abstract

The present invention relates to a kind of micro/nano-fibre film, in particular to a kind of porous cellulose acetate composite micro/nano tunica fibrosa, centrifugal spinning preparation method and its application at heavy metal ion adsorbed aspect belong to functional nano technical field of fiber preparation.This method comprises the following steps: (1) preparation of centrifugal spinning solution: raw material CA and MMT are dissolved in methylene chloride (DCM) and dimethyl sulfoxide (DMSO) in the mixed solvent, finely dispersed centrifugal spinning solution is obtained after stirring, wherein CA mass concentration is 12~16wt%, and MMT mass fraction is 0.1~3%；(2) centrifugal spinning: centrifugal spinning is carried out using centrifugal spinning solution made from step (1), obtains porous cellulose acetate composite micro/nano tunica fibrosa.Preparation method of the present invention is simple, can rapidly and efficiently prepare the porous cellulose acetate composite micro/nano tunica fibrosa with heavy metal ion adsorbed ability.

Description

Porous cellulose acetate composite micro/nano fiber membrane, preparation method of centrifugal spinning and its Application in the adsorption of heavy metal ions

technical field

The invention relates to a micro/nano fiber membrane, in particular to a porous cellulose acetate composite micro/nano fiber membrane, a centrifugal spinning preparation method and its application in heavy metal ion adsorption, belonging to the technical field of functional nanofiber preparation.

Background technique

In recent years, especially in developing countries, with the rapid development of modern industries such as electroplating, mining, chemical fertilizers, leather, batteries, papermaking and pesticides, a large amount of wastewater containing heavy metals has been discharged directly or indirectly into the environment. The pollution of water resources by ions has become a prominent and severe environmental problem. Common heavy metal ions include copper Cu(II), lead Pb(II), nickel Ni(II), mercury Hg(II), etc. Since these ions cannot be degraded and decomposed naturally in nature, they are found in soil, rivers and lakes and other surface water and They exist in groundwater for a long time and eventually accumulate in the human body through the food chain. Therefore, even trace amounts of these heavy metal ions in water still cause harm to human health. Traditional heavy metal ion wastewater treatment technologies include chemical precipitation, dialysis, ion exchange, activated carbon adsorption, and co-precipitation adsorption. Adsorption is a promising method for treating wastewater containing heavy metal ions, which has the advantages of simple operation and low cost.

Porous fibers not only have the advantages of small diameter of traditional non-porous fibers, but also have nano- or micro-scale pores on the surface or inside, with larger roughness and specific surface area, which will promote the improvement of storage capacity and diffusivity. The presence of hydroxyl and carbonyl groups in cellulose acetate (CA) has a strong affinity for heavy metals, so it can be used as an adsorption material for heavy metal ions. Montmorillonite (MMT) has a large specific surface area and ion exchange capacity, good adsorption performance, and has a special effect on the adsorption of heavy metal ions in wastewater. Using montmorillonite to treat heavy metal wastewater has a low release rate during desorption, and secondary pollution is not easy to occur. Montmorillonite is rich in resource reserves, has a huge specific surface area and excellent adsorption capacity, and at the same time, cations between montmorillonite crystal layers can be exchanged, and has good expansibility.

Most nano-acetate fibers are prepared by electrospinning, which has the disadvantages of low preparation efficiency and a large amount of consumables. Centrifugal spinning, on the other hand, overcomes the limitations encountered by electrospun acetate fiber fabrication methods and enables the production of micro/nanofibers at high speed and low cost. This design does not need to apply a high-voltage electric field, can prepare polymer micro/nano fibers that are not restricted by conductivity, does not require special dielectric properties of raw materials, and does not require rapid high-temperature airflow in melt-blown spinning, which can greatly save cost, and its production efficiency has been greatly improved. Therefore, the preparation method of green and efficient porous composite heavy metal ion adsorption materials has attracted much attention.

Contents of the invention

The invention provides a centrifugal spinning preparation method of a porous cellulose acetate composite micro/nano fiber membrane.

The technical solution adopted by the present invention to solve its technical problems is:

A kind of centrifugal spinning preparation method of porous cellulose acetate composite micro/nano fiber membrane, the method comprises the following steps:

(1) Preparation of centrifugal spinning solution: dissolve the raw materials CA and MMT in a mixed solvent of dichloromethane (DCM) and dimethyl sulfoxide (DMSO), and obtain a uniformly dispersed centrifugal spinning solution after stirring, wherein the mass of CA Concentration is 12～16wt%, MMT mass fraction is 0.1～3%; (2) Centrifugal spinning: adopt the centrifugal spinning solution that step (1) makes to carry out centrifugal spinning, obtain porous cellulose acetate composite micro/nano fiber membrane.

The preparation method of the invention is simple, and the porous cellulose acetate composite micro/nano fiber membrane can be prepared rapidly and efficiently. Due to the advantages of small fiber diameter, large specific surface area, and high porosity, nanofibrous materials are widely used in tissue engineering scaffolds, drug delivery, filter media, artificial blood vessels, biochips, nanosensors, optics, composite materials, and other fields. Micro/nanofibrous membranes have attracted the attention of many researchers due to the remarkable nanoscale effect of micro/nanofibers. Under the requirements of the era of low-carbon economy, environmental protection, social security and human health, fiber/fabric is moving towards the research and development and development of high-tech fiber materials with higher technical content and less impact on resources, high-performance and functional high-tech fiber materials. Development in the direction of industrialization.

At present, the preparation of porous composite micro/nanofiber membranes mainly focuses on the method of electrospinning, which is still far from practical and application requirements in terms of cost, scale, and controllability. Therefore, in order to realize the controllable and large-scale preparation of micro/nanofibrous membranes, it is necessary to explore suitable new technologies and methods to reduce costs, expand scale, and improve preparation controllability. Based on the centrifugal spinning technology with industrial application prospects, it is a water-saving, energy-saving, green and non-polluting process, which can prepare micro/nano fibers from polymers, ceramics, and composite materials. Existing data have shown that the yield of nanofibers by centrifugal spinning technology can be at least two orders of magnitude higher than that of electrospinning. Centrifugal spinning has opened up a new way for the preparation of porous micro/nanofibers and has a good development prospect.

As preferably, cellulose acetate (CA) molar mass M _W =100000g/mol, its chain structure formula is:

The structural formula of MMT is (Al, Mg) ₂ [SiO ₁₀ ](OH) ₂ ·n H ₂ O, and its structure is shown as follows:

Preferably, in the mixed solvent of dichloromethane (DCM) and dimethyl sulfoxide (DMSO), the mass fraction of DMSO is 15-25%. Preferably, the optimum mass ratio of dichloromethane (DCM) to dimethyl sulfoxide (DMSO) is 8:2.

As preferably, the preparation method of the centrifugal spinning solution described in step (1) is as follows: 1.3g CA and 0.1g MMT are placed in a 20ml sample bottle, pipette 6.88g DCM and 1.72g DMSO in the sample bottle, and the sample bottle Seal with plastic wrap, raw material tape and parafilm, heat to 35° C. and stir for more than 12 hours to obtain a centrifugal spinning solution.

As preferably, the centrifugal spinning device that centrifugal spinning adopts comprises motor, spinning head and collecting rod, and spinning head is installed on the rotating shaft top of motor and is driven to rotate by motor, has the cavity that holds spinning liquid in spinning head, The top of the spinning head is provided with a liquid injection port, the side wall of the spinning head is provided with spinneret holes communicating with the cavity, and the collecting rods are arranged around the spinning head.

Preferably, the motor speed is generally 5000-15000 rpm/min. The distance between the spinning head and the collecting rod is controlled at 10cm±2cm, and the diameter of the spinneret hole is 0.4mm-0.6mm. The collecting rods are center-symmetrically distributed with the spinning head as the axis, and the number of collecting rods is 6-12. The spinning head is composed of a spinning shell and a circular sealing ring. The spinning shell is a cylindrical structure with an open bottom. The bottom end of the spinning shell extends outwards to form a ring-shaped edge. A step is set in the middle of the ring-shaped edge. The circular The sealing ring cooperates with the step to seal the opening of the spinning shell, and the bottom of the circular sealing ring is flush with the bottom plane of the annular rim. The spinning head is made of polytetrafluoroethylene. The height difference between the spinning head and the top of the collecting rod is 1-2 cm. Spinning holes are located 2/3 from the bottom surface of the spinning head to the top surface, and there are 6-8 symmetrically arranged on the same plane. A pair of blades are arranged horizontally on the annular edge. When spinning, an upward airflow is formed so that the spun fibers are collected in the upper half of the collecting rod and not deposited at the bottom.

A porous cellulose acetate composite micro/nano fiber membrane prepared by the method.

An application of the porous cellulose acetate composite micro/nano fiber membrane in the adsorption of heavy metal ions.

For the porous cellulose acetate composite micro/nano fiber membrane of the present invention, first, cellulose acetate and montmorillonite are placed in a mixed solvent of dichloromethane and dimethyl sulfoxide, and after stirring, a uniformly dispersed centrifugal spinning solution is obtained, Then the centrifugal spinning solution is obtained by centrifugal spinning. The centrifugal spinning preparation method of the porous composite micro/nano fiber membrane has the following characteristics:

1. The preparation method of the present invention is simple and convenient, and the reaction conditions are easy to realize and control;

2. By adjusting the amount of cellulose acetate and the amount of montmorillonite, the morphology and structure of the porous cellulose acetate composite micro/nano fiber membrane can be controlled;

3. The fiber diameter of the porous composite micro/nano fiber membrane can be regulated by adjusting the spinning parameters such as: motor speed, spinneret diameter, and collecting rod distance;

4. It is more efficient to prepare porous cellulose acetate composite micro/nanofiber membranes by centrifugal spinning, and it can be applied to the field of heavy metal ion adsorption.

Description of drawings

Fig. 1 is the structural representation of centrifugal spinning device of the present invention;

Fig. 2 is the structural representation of spinning head among Fig. 1;

Explanation of symbols: 1 motor; 2 spinning head; 3 collecting rod; 4 blade; 5 fiber; 6 liquid injection port; 7 spinneret hole; 8 spinning shell;

Figure 3 is the SEM images of porous composite micro/nanofibrous membranes with different MMT mass fractions × 100 times and × 2000 times;

Figure 4 is the SEM images of porous composite micro/nanofibrous membranes with different MMT mass fractions × 100 times and × 2000 times;

Fig. 5 is the EDS figure of porous cellulose acetate micro/nano fiber film and composite micro/nano fiber film of the present invention, wherein a is porous cellulose acetate micro/nano fiber film, b is porous cellulose acetate composite micro/nano fiber Membranes (composite of CA and MMT);

Fig. 6 is the adsorption curve of porous cellulose acetate composite micro/nano fiber membrane of the present invention to Cu ²⁺ ;

Fig. 7 is the variation curve of the adsorption amount of Cu ²⁺ by the porous composite micro/nanofibrous membrane with different MMT mass fractions;

Figure 8 is a diagram of the adsorption capacity of the porous cellulose acetate composite micro/nanofiber membrane for reuse.

Detailed ways

The technical solution of the present invention will be further specifically described below through specific examples. It should be understood that the implementation of the present invention is not limited to the following examples, and any modifications and/or changes made to the present invention will fall within the protection scope of the present invention.

In the present invention, unless otherwise specified, all parts and percentages are in weight units, and the equipment and raw materials used can be purchased from the market or commonly used in the field. The methods in the following examples, unless otherwise specified, are conventional methods in the art.

The centrifugal spinning device that the centrifugal spinning described in the following examples adopts is shown in Figure 1 and Figure 2, comprises motor 1, spinning head 2 and collecting rod 3, and spinning head is installed on the rotating shaft top of motor and is driven by motor Rotate, there is a cavity in the spinning head to accommodate the spinning solution, the top of the spinning head is provided with a liquid injection port 6, the side wall of the spinning head is provided with a spinneret hole 7 communicating with the cavity, and the collecting rod surrounds the spinning Head lap set.

The distance between the spinning head and the collecting rod is controlled at 10cm ± 2cm, and the diameter of the spinneret hole is 0.4mm in this embodiment, and can be adjusted to 0.5 or 0.6mm in actual production. In order to ensure better collection of fiber membranes, the height difference between the spinning head and the top of the collecting rod is 1-2 cm. The collecting rods are center-symmetrically distributed with the spinning head as the axis, and the number of collecting rods is 8.

The spinning head is made of polytetrafluoroethylene. The spinning head is composed of a spinning shell 8 and a circular sealing ring 9. The spinning shell is a cylindrical structure with an open bottom. The bottom end of the spinning shell extends outwards to form a ring-shaped edge 10, and a step 11 is arranged in the middle of the ring-shaped edge. The circular sealing ring cooperates with the step to seal the opening of the spinning shell, and the bottom of the circular sealing ring is flush with the bottom plane of the ring rim. The spinneret holes are located about 2/3 of the distance from the bottom surface of the spinneret to the top surface, and 8 holes are arranged symmetrically on the same plane.

A pair of blades 4 are also arranged along the horizontal direction on the annular edge. When spinning, an upward airflow is formed so that the spun fibers are collected in the upper half of the collecting rod and not deposited at the bottom.

During centrifugal spinning, the spinning head is driven by the motor to rotate, and the spinning solution is sprayed out from the spinneret hole of the spinning head, and moves between the spinneret hole and the collecting rod to be stretched, and at the same time, the solvent volatilizes to form fibers, which pass The collection rod receives the fibrous membrane. The motor speed is generally 5000-15000rpm/min.

Compared with electrospinning, centrifugal spinning equipment is simple, low in cost, and can spin higher concentration of spinning solution than electrospinning. Using this centrifugal spinning device is safer and more efficient in use; single nozzle electrospinning The productivity of the silk device is 1-100 mg/hour, and the productivity of centrifugal spinning can be increased by at least two orders of magnitude compared with electrospinning.

Example 1

Construction of Porous Cellulose Acetate Micro/Nanofibrous Membranes by Centrifugal Spinning

(1) Accurately weigh four parts of 1.3g cellulose acetate (CA) (wherein the molar mass M=100000g/mol of CA) with an analytical balance and place them in four 20ml sample bottles respectively, then pipette into the four sample bottles respectively. Take 5.22g DCM and 3.48g DMSO (mass ratio is 6:4), 6.09g DCM and 2.61g DMSO (mass ratio is 7:3), 6.96g DCM and 1.74gDMSO (mass ratio 8:2), 7.83g DCM and 0.87g DMSO (mass ratio: 9:1), seal the sample bottle with plastic wrap, raw tape and parafilm, heat to 35°C and stir for more than 12 hours to finally obtain a centrifugal spinning solution with evenly dispersed CA.

(2) Adopt the centrifugal spinning device shown in Figure 1 to carry out centrifugal spinning, set the rotating speed as 8000rpm/min, the distance between the collecting rods is 10cm, and the diameter of the spinneret hole is 0.4mm, get 5ml spinning solution sample in the spinning head, Turn on the motor, and get the porous CA composite micro/nano fiber membrane through the collecting rod.

Example 2

A kind of centrifugal spinning preparation method of porous cellulose acetate composite micro/nano fiber membrane, the specific steps of the method are as follows:

(1) Accurately weigh 1.3g CA, 0.05g (0.5%) MMT (placed in a 20ml sample bottle, pipette 6.92g DCM and 1.73g DMSO (mass ratio 8:2) into the sample bottle with an analytical balance. The sample bottle was sealed with plastic wrap, raw material tape and parafilm, heated to 35°C and stirred for more than 12 hours to finally obtain a centrifugal spinning solution with evenly dispersed CA.

(2) Adopt the centrifugal spinning device shown in Figure 1 to carry out centrifugal spinning, set the rotating speed as 8000rpm/min, the distance between the collecting rods is 10cm, and the diameter of the spinneret hole is 0.4mm, get 5ml spinning solution sample in the spinning head, Turn on the motor, and get the porous CA composite micro/nano fiber membrane through the collecting rod.

Example 3

A kind of centrifugal spinning preparation method of porous cellulose acetate composite micro/nano fiber membrane, the specific steps of the method are as follows:

(1) Accurately weigh 1.3g CA and 0.1g (1%) MMT with an analytical balance and place it in a 20ml sample bottle, pipette 6.88g DCM and 1.72g DMSO (mass ratio 8:2) into the sample bottle, and the sample The bottle is sealed with a plastic wrap, a raw material tape and a sealing film, heated to 35° C. and stirred for more than 12 hours to obtain a centrifugal spinning solution.

(2) Adopt the centrifugal spinning device shown in Figure 1 to carry out centrifugal spinning, set the rotating speed as 8000rpm/min, the distance between the collecting rods is 10cm, and the diameter of the spinneret hole is 0.4mm, get 5ml spinning solution sample in the spinning head, Turn on the motor, and get the porous CA composite micro/nano fiber membrane through the collecting rod.

Example 4

A kind of centrifugal spinning preparation method of porous cellulose acetate composite micro/nano fiber membrane, the specific steps of the method are as follows:

(1) Accurately weigh 1.3g CA and 0.2g (2%) MMT with an analytical balance and place it in a 20ml sample bottle, pipette 6.80g DCM and 1.70g DMSO (mass ratio 8:2) into the sample bottle, and place the sample Seal the bottle with plastic wrap, raw material tape and parafilm, heat to 35°C and stir for more than 12 hours to finally obtain a centrifugal spinning solution with evenly dispersed CA.

(2) Adopt the centrifugal spinning device shown in Figure 1 to carry out centrifugal spinning, set the rotating speed as 8000rpm/min, the distance between the collecting rods is 10cm, and the diameter of the spinneret hole is 0.4mm, get 5ml spinning solution sample in the spinning head, Turn on the motor and get the CA micro/nanofiber membrane through the collecting rod.

Example 5

A kind of centrifugal spinning preparation method of porous cellulose acetate composite micro/nano fiber membrane, the specific steps of the method are as follows:

(1) Accurately weigh 1.3g CA and 0.3g (3%) MMT with an analytical balance and place it in a 20ml sample bottle, pipette 6.72g DCM and 1.68g DMSO (mass ratio 8:2) into the sample bottle, and place the sample Seal the bottle with plastic wrap, raw material tape and parafilm, heat to 35°C and stir for more than 12 hours to finally obtain a centrifugal spinning solution with evenly dispersed CA.

(2) Adopt the centrifugal spinning device shown in Figure 1 to carry out centrifugal spinning, set the rotating speed as 8000rpm/min, the distance between the collecting rods is 10cm, and the diameter of the spinneret hole is 0.4mm, get 5ml spinning solution sample in the spinning head, Turn on the motor and get the CA micro/nanofiber membrane through the collecting rod.

Comparative example 1

A kind of centrifugal spinning preparation method of porous cellulose acetate composite micro/nano fiber membrane, the specific steps of the method are as follows:

(1) Accurately weigh 1.3g CA and 0.4g (4%) MMT with an analytical balance and place it in a 20ml sample bottle, pipette 6.64g DCM and 1.66g DMSO (mass ratio 8:2) into the sample bottle, and place the sample Seal the bottle with plastic wrap, raw material tape and parafilm, heat to 35°C and stir for more than 12 hours to finally obtain a centrifugal spinning solution with evenly dispersed CA.

(2) Adopt the centrifugal spinning device shown in Figure 1 to carry out centrifugal spinning, set the rotating speed as 8000rpm/min, the distance between the collecting rods is 10cm, and the diameter of the spinneret hole is 0.4mm, get 5ml spinning solution sample in the spinning head, Turn on the motor. However, in the centrifugal spinning, the spinning liquid becomes broken filaments and cannot be spun into a fibrous membrane, which proves that when the concentration of MMT is 4%, it cannot be spun.

The inventor continued to do the experiment when the concentration of MMT was 5%, but it was also unable to spin.

Comparative example 2

A kind of centrifugal spinning preparation method of porous cellulose acetate composite micro/nano fiber membrane, the specific steps of the method are as follows:

(1) Accurately weigh 1.4g CA and 0.4g (4%) MMT with an analytical balance and place it in a 20ml sample bottle, pipette 6.56g DCM and 1.64g DMSO (mass ratio 8:2) into the sample bottle, and place the sample Seal the bottle with plastic wrap, raw material tape and parafilm, heat to 35°C and stir for more than 12 hours to finally obtain a centrifugal spinning solution with evenly dispersed CA.

(2) Adopt the centrifugal spinning device shown in Figure 1 to carry out centrifugal spinning, set the rotating speed as 8000rpm/min, the distance between the collecting rods is 10cm, and the diameter of the spinneret hole is 0.4mm, get 5ml spinning solution sample in the spinning head, Turn on the motor and get the CA micro/nanofiber membrane through the collecting rod. However, during the preparation process, due to the high viscosity of the spinning solution, it is difficult to form filaments under this spinning parameter, which proves that the concentration of CA cannot be loaded with 4% MMT.

Application Verification Test of Porous Cellulose Acetate Composite Micro/Nanofiber Membrane in Adsorption of Heavy Metal Ions

(1) Scanning electron microscope observation of surface morphology of porous CA/MMT composite fiber membrane

The ULTRA55-36-73 field emission scanning electron microscope was used to observe the CA fiber membrane prepared in Example 1. Compared with Figure 3, it can be seen that only when the solvent mass ratio is 8:2, the CA fiber membrane with a porous surface structure can be prepared.

The surface morphology of the porous fiber membranes prepared in Examples 2, 3, 4, and 5 (in the centrifugal spinning solution, the mass concentration of MMT is 0.5%, 1%, 2%, and 3%), the results are shown in Figure 4. Comparing the SEM images of composite fiber membranes with different amounts of MMT added, it can be known that the addition of MMT did not affect the porous structure of the composite fibers, and the diameter of the composite fibers also increased with the increase of the mass fraction. However, when the mass concentration of MMT in the centrifugal spinning solution is greater than 4%, the filaments become broken and cannot be spun into fiber membranes.

(2) Porous CA/MMT composite fiber membrane X-ray spectrometer (EDS) analysis

Adopt K-Alpha type x-ray spectrometer (EDS) to carry out surface elemental analysis to the porous composite fiber membrane of preparation, by test result (Fig. 5) as can be known, in the composite fiber membrane that the present invention makes, Si, two kinds of elements of Al have occurred , which is the main constituent element of MMT, so it can be proved that MMT is successfully loaded on the fiber membrane.

(3) Adsorption curve of Cu ²⁺ on porous CA/MMT composite fiber membrane

Adsorption experiment:

The porous composite fiber membrane (0.02g) prepared by Example 5 is immersed in the solution containing Cu ²⁺ (100mg/L), and the solution is placed in a shaking water bath for shaking (allowing the fiber membrane to fully contact with the heavy metal ion solution ), let the fibers carry out automatic adsorption, the constant temperature is 25°C, and the adsorption time is 24h. After the adsorption, the fiber membrane was taken out and soaked in deionized water for 2 hours, and then dried for later use. Samples were taken from the adsorbed heavy metal ion solution, and the absorbance was tested by an AA-110 atomic absorption spectrometer, and the adsorption amount of the heavy metal ion by the composite fiber membrane was obtained through calculation.

The adsorption curve of the porous cellulose acetate composite fiber membrane prepared in Example 5 of the present invention to Cu ²⁺ is shown in Figure 6. As the adsorption time increases, the adsorption amount of Cu ²⁺ also increases, and when it reaches 12h Its adsorption capacity reaches a saturated maximum value of 54.24 mg/g. It can be seen from the test results that the prepared porous composite fiber membrane has good adsorption to Cu ²⁺ .

(4) Adsorption of Cu ²⁺ by porous composite fiber membranes with different MMT mass fractions

Adsorption experiment:

The porous composite fiber membrane (0.02g) prepared by embodiment 2, 3, 4, 5 is immersed in the solution containing Cu ²⁺ (100mg/L), and the solution is placed in a oscillating water bath for shaking (let the fiber membrane Fully contact with the heavy metal ion solution), let the fiber carry out automatic adsorption, the constant temperature is 25°C, and the adsorption time is 24h. After the adsorption, the fiber membrane was taken out and soaked in deionized water for 2 hours, and then dried for later use. Samples were taken from the adsorbed heavy metal ion solution, and the absorbance was tested by an AA-110 atomic absorption spectrometer, and the adsorption amount of the heavy metal ion by the composite fiber membrane was obtained through calculation.

By comparing the adsorption of Cu ²⁺ by porous composite fiber membranes with different MMT additions, the results are shown in Figure 7. As the amount of MMT increased, the adsorption capacity of the composite fiber membrane also increased, and the composite fiber membrane with a mass fraction of MMT of 3% had the largest adsorption capacity for Cu ²⁺ .

(5) Reusability test of porous CA/MMT composite fiber membrane

After cleaning and drying the adsorbed composite fiber membrane (the fiber membrane obtained in (3) and (4) above), put it into a 100 mg/g sodium edetate solution for desorption, wash and dry after desorption dry, and then carry out the adsorption test. The recycling adsorption capacity is shown in Figure 8. After two desorptions, 83% of the adsorption effect can be maintained, which proves that the prepared porous composite fiber membrane has recycling performance, which is in line with the concept of resource-saving and environment-friendly development.

The embodiment described above is only a preferred solution of the present invention, and does not limit the present invention in any form. There are other variations and modifications on the premise of not exceeding the technical solution described in the claims.

Claims (9)

1. a centrifugal spinning preparation method of porous cellulose acetate composite micro/nano fiber membrane, is characterized in that the method comprises the steps: (1) Preparation of centrifugal spinning solution: Dissolve the raw materials cellulose acetate (CA) and montmorillonite (MMT) in a mixed solvent of dichloromethane (DCM) and dimethyl sulfoxide (DMSO), and get dispersed after stirring Uniform centrifugal spinning solution, wherein the mass concentration of CA is 12-16 wt%, and the mass fraction of MMT is 0.1-3%; (2) Centrifugal spinning: the centrifugal spinning solution prepared in step (1) is used for centrifugal spinning to obtain a porous cellulose acetate composite micro/nano fiber membrane. 2. The centrifugal spinning preparation method according to claim 1, characterized in that: CA molar mass M _W =100000g/mol, and its chain structure formula is: The structural formula of MMT is (Al, Mg) ₂ [SiO ₁₀ ](OH) ₂ ·n H ₂ O, and its structure is shown as follows: 3. The centrifugal spinning preparation method according to claim 1, characterized in that: in the mixed solvent of dichloromethane (DCM) and dimethyl sulfoxide (DMSO), the mass fraction of DMSO is 15-25%. 4. centrifugal spinning preparation method according to claim 1 is characterized in that: in dichloromethane (DCM) and dimethyl sulfoxide (DMSO) mixed solvent, dichloromethane (DCM) and dimethyl sulfoxide (DMSO) in a mass ratio of 8:2. 5. the centrifugal spinning preparation method according to claim 1, is characterized in that: the preparation method of centrifugal spinning solution described in step (1) is as follows: 1.3g CA and 0.1g MMT are placed in 20ml sample bottle, to Pipette 6.88g DCM and 1.72g DMSO into the sample bottle, seal the sample bottle with plastic wrap, raw tape and parafilm, heat to 35-38°C and stir for more than 12 hours to obtain a centrifugal spinning solution. 6. the centrifugal spinning preparation method according to claim 1, is characterized in that: the centrifugal spinning device that centrifugal spinning adopts comprises motor, spinning head and collecting rod, and spinning head is installed on the rotating shaft top of motor and is controlled by motor. Driven to rotate, there is a cavity in the spinning head to accommodate the spinning liquid, the top of the spinning head is provided with a liquid injection port, the side wall of the spinning head is provided with a spinneret hole connected to the cavity, and the collecting rod surrounds the spinning head Circle set. 7. The centrifugal spinning preparation method according to claim 6, characterized in that: during centrifugal spinning, the spinneret hole diameter is selected as 0.4mm, the spinning speed is adjusted to 10000-12000rpm/min, and the spinning solution is The fibers are ejected from the spinneret hole of the head, and the fiber film is received by the collecting rod. 8. The porous cellulose acetate composite micro/nano fiber membrane that the method for claim 1 makes. 9. The application of the porous cellulose acetate composite micro/nano fiber membrane according to claim 8 in the adsorption of heavy metal ions.