Method for preparing functional ultra-fine porous nanofiber catalytic filtration membrane

Abstract

The application discloses a preparation method of a functional superfine porous nanofiber catalytic filter membrane, and specifically implements the method in the following way: step 1, PA6 / PVP spinning solution is prepared; step 2, PA6 / PVP composite nanofiber is prepared by electrostatic spinning with the PA6 / PVP spinning solution prepared in step 1 as raw material; step 3, PA6@TiO2 mixed electrospinning solution is prepared; step 4, PA6 / PVP@TiO2 composite nanofiber is prepared by electrostatic spraying with the PA6 / PVP composite nanofiber obtained in step 2 and the PA6@TiO2 mixed electrospinning solution obtained in step 2 as raw material; and step 5, PA6@TiO2 superfine porous nanofiber catalytic filter membrane is prepared by hydrothermal method with the PA6 / PVP@TiO2 composite nanofiber prepared in step 4 as raw material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanofiltration materials, and particularly relates to a preparation method of a functional ultrafine porous nanofiber catalytic filtration membrane. BACKGROUND

[0002] The filtration method has the advantages of wide adaptability, good treatment effect, simple operation method and the like in deep treatment of water pollution, and has become one of the most effective methods for treating water pollutants. The filtration method is a method for purifying pollutants in water by using a filtration material with high porosity, high surface activity and large specific surface area. One or several components in a water sample are intercepted or adsorbed on the surface of the porous filtration material, so that the purpose of purifying the water body is achieved.

[0003] The electrospun nanofiber has good application prospects in the field of filtration materials due to the advantages of high specific surface area, high aspect ratio, high porosity, good pore connectivity, simple preparation device, low cost, various types of fibers and controllable process. The existing nanofiber filtration material has the problems of limited filtration efficiency, unstable performance, high preparation cost and membrane pollution in application. The PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane prepared by electrospinning combined with electrostatic spraying is applied to the filtration of complex pollutants in water, has the advantages of simple preparation method, low cost, good anti-pollution property and high catalytic filtration efficiency, and to some extent, overcomes the shortcomings of the traditional filtration membrane. SUMMARY

[0004] The purpose of the application is to provide a preparation method of a functional ultrafine porous nanofiber catalytic filtration membrane, which solves the problems of limited filtration efficiency, unstable performance, high preparation cost and membrane pollution of the existing nanofiber filtration material in application.

[0005] In order to achieve the above purpose, the technical scheme adopted by the application is as follows: a preparation method of a functional ultrafine porous nanofiber catalytic filtration membrane is implemented according to the following mode.

[0006] Step 1, configuring PA6 / PVP spinning solution;

[0007] Step 2, using the PA6 / PVP spinning solution configured in step 1 as raw material, electrospinning is used to prepare PA6 / PVP composite nanofiber;

[0008] Step 3, configuring PA6@TiO2 mixed electrospinning solution;

[0009] Step 4, using the PA6 / PVP composite nanofiber obtained in step 2 and the PA6@TiO2 mixed electrospinning solution obtained in step 2 as raw material, electrostatic spraying method is used to prepare PA6 / PVP@TiO2 composite nanofiber;

[0010] Step 5, using the PA6 / PVP@TiO2 composite nanofiber prepared in step 4 as raw material, a PA6@TiO2 ultra-fine porous nanofiber catalytic filtration membrane is prepared by a hydrothermal method.

[0011] As a preferred technical solution of the present application, in the step 1, the PA6 / PVP spinning solution is configured as follows: first, the dried PA6 is weighed and added into the formic acid solution, and stirred at a stirring speed of 50 r / min-80 r / min for 2 h-4 h, then the PVP powder is weighed and added into the formic acid solution, and continues to be stirred for 10 h-20 h until completely dissolved to obtain a mixed solution, and the mixed solution is placed in an ultrasonic cleaner for ultrasonic treatment for 0.5 h-2 h to obtain a PA6 / PVP spinning solution with a concentration of 8 wt.%-12 wt.%.

[0012] As a preferred technical solution of the present application, in the step 2, the PA6 / PVP composite nanofiber is prepared by electrospinning as follows: the prepared PA6 / PVP spinning solution is injected into the liquid storage cylinder of the spinning nozzle of the electrospinning machine, the injection pump is connected to the voltage power supply, the spinning nozzle is placed on one side of the receiving device of the electrospinning machine and the flow rate of the spinning solution is controlled by the injection pump, the tin foil paper is placed on the receiving cylinder of the receiving device of the electrospinning machine, the receiving cylinder rolling switch is turned on, and then the single needle spinning is started to spin the spinning solution in the liquid storage cylinder, and a layer of uniform PA6 / PVP composite nanofiber can be obtained on the surface of the tin foil paper.

[0013] As a preferred technical solution of the present application, in the step 2, the spinning voltage is 16 KV-22 KV, the spinning distance is 15 cm-20 cm, the feeding rate is 0.3 mL / h-1.5 mL / h, the cylinder rotation speed is 300 rpm-550 rpm, and the collection time is 240 min-480 min.

[0014] As a preferred technical solution of the present application, in the step 3, the PA6@TiO2 mixed electrospinning solution is configured as follows: first, the PA6 solid is weighed and added into the formic acid solution, and stirred at a stirring speed of 50 r / min-80 r / min for 2 h-3 h, then the TiO2 is dissolved in the formic acid solution, and magnetically stirred at 40℃-60℃ for 8 h-12 h until the TiO2 is completely dissolved, and finally ultrasonic treatment is performed for 0.5 h-2 h; the mass concentration of PA6 in the PA6@TiO2 mixed electrospinning solution is 4 wt.%-10 wt.%, and the mass concentration of TiO2 is 4.5 wt.%-8.5 wt.%.

[0015] As a preferred technical scheme of the present application, in the step 4, the PA6 / PVP@TiO2 composite nanofiber is prepared by electrostatic spraying method, specifically as follows: the prepared PA6@TiO2 mixed electrospinning liquid is injected into the liquid storage cylinder of the spinning nozzle of the electrospinning machine, the injection pump is connected to the voltage power supply, the spinning nozzle is placed on the left side of the receiving device of the electrospinning machine and the flow rate of the spinning liquid is controlled by the injection pump, the PA6 / PVP composite nanofiber prepared in the step is placed on the receiving cylinder of the receiving device of the electrospinning machine, the receiving cylinder rolling switch is turned on, and then the single needle spinning is started to electrostatically spray the spinning liquid in the liquid storage cylinder, so that a uniform layer of PA6 / PVP@TiO2 composite nanofiber is obtained.

[0016] As a preferred technical scheme of the present application, in the step 4, the voltage of the electrospinning is 25KV-30KV, the electrospinning distance is 15cm-20cm, the liquid feeding rate is 1.0mL / h-2.5mL / h, the roller rotating speed is 300rpm-550rpm, and the collection time is 240min-480min.

[0017] As a preferred technical scheme of the present application, in the step 5, the PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane is prepared by hydrothermal method, specifically as follows: the PA6 / PVP@TiO2 composite nanofiber obtained in the step 4 is placed in a polytetrafluoroethylene-lined stainless steel autoclave and deionized water is added, then the autoclave is placed in a vacuum drying box, heated at 80℃-100℃ for 6h-10h, taken out and naturally cooled to room temperature, washed with deionized water for 3-6 times, and then placed in an oven at 60℃-80℃ for drying for 4h-8h, to obtain the PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane.

[0018] The present application has the advantages that: the preparation method of the functional ultrafine porous nanofiber catalytic filtration membrane of the present application uses electrospinning combined with electrostatic spraying to prepare the PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane, which has a lower fiber diameter and a narrower pore size distribution than general filtration materials, significantly improves the membrane filtration performance, and the material has excellent hydrophilicity and self-cleaning property. The preparation process of the present application is simple, low in cost, strong in anti-pollution, and particularly suitable for deep treatment of wastewater containing micron-level, sub-micron-level pollutants and organic dyes. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a preparation device schematic diagram of the PA6@TiO2 ultrafine nanofiber for wastewater deep filtration treatment of the present application;

[0020] Figure 2is a scanning electron microscope schematic diagram of PA6@TiO2 ultra-fine porous nanofiber in embodiment 4 for wastewater advanced filtration treatment of the present application;

[0021] In the figure, 1. voltage power supply; 2. injection pump; 3. spinning nozzle; 4. drum receiving device. DETAILED DESCRIPTION

[0022] The preparation method of a functional ultra-fine porous nanofiber catalytic filtration membrane of the present application is specifically implemented according to the following steps:

[0023] Step 1, configure PA6 / PVP spinning solution: first, weigh the dried PA6 and add it to the formic acid solution, and stir at a stirring speed of 50 r / min-80 r / min for 2 h-4 h, then weigh the PVP powder and add it to the formic acid solution, and continue to stir for 10 h-20 h until completely dissolved to obtain a mixed solution, place the mixed solution in an ultrasonic cleaner and ultrasonic for 0.5 h-2 h to obtain a PA6 / PVP spinning solution with a concentration of 8 wt.%-12 wt.%;

[0024] Step 2, using the PA6 / PVP spinning solution configured in step 1 as raw material, PA6 / PVP composite nanofiber is prepared by electrospinning as follows: inject the configured PA6 / PVP spinning solution into the liquid storage cylinder of the spinning nozzle of the electrospinning machine, connect the injection pump to the voltage power supply, place the spinning nozzle on one side of the receiving device of the electrospinning machine and control the flow rate of the spinning solution through the injection pump, place tin foil paper on the receiving cylinder of the receiving device, turn on the receiving cylinder rolling switch, then start single needle spinning to spin the spinning solution in the liquid storage cylinder, and a layer of uniform PA6 / PVP composite nanofiber can be obtained on the surface of the tin foil paper; the spinning voltage is 16 KV-22 KV, the spinning distance is 15 cm-20 cm, the feeding rate is 0.3 mL / h-1.5 mL / h, the drum rotation speed is 300 rpm-550 rpm, and the collection time is 240 min-480 min;

[0025] Step 3, configure PA6@TiO2 mixed electrospinning solution: first, weigh the PA6 solid and add it to the formic acid solution, and stir at a stirring speed of 50 r / min-80 r / min for 2 h-3 h, then dissolve TiO2 in the formic acid solution, and magnetically stir at 40℃-60℃ for 8 h-12 h until TiO2 is completely dissolved, finally ultrasonic treatment for 0.5 h-2 h; the mass concentration of PA6 in the PA6@TiO2 mixed electrospinning solution is 4 wt.%-10 wt.%, and the mass concentration of TiO2 is 4.5 wt.%-8.5 wt.%;

[0026] Step 4, PA6 / PVP composite nanofiber obtained in step 2 and PA6@TiO2 mixed electrospinning liquid obtained in step 2 are used as raw materials to prepare PA6 / PVP@TiO2 composite nanofiber by electrostatic spraying method as follows: PA6 / PVP@TiO2 composite nanofiber prepared by electrostatic spraying method is carried out as follows: the prepared PA6@TiO2 mixed electrospinning liquid is injected into the liquid storage cylinder of the electrospinning machine, the injection pump is connected to the voltage power supply, the spinning nozzle is placed on the left side of the electrospinning machine receiving device and the flow rate of the spinning liquid is controlled by the injection pump, the PA6 / PVP composite nanofiber prepared in the step is placed on the receiving cylinder of the electrospinning machine receiving device, the receiving cylinder rolling switch is turned on, and then the single needle spinning is started to electrostatically spray the spinning liquid in the liquid storage cylinder, so that a uniform layer of PA6 / PVP@TiO2 composite nanofiber is obtained; the voltage of electrospinning is 25KV-30KV, the distance of electrospinning is 15cm-20cm, the feeding rate is 1.0mL / h-2.5mL / h, the rotating speed of the cylinder is 300rpm-550rpm, and the collection time is 240min-480min;

[0027] Step 5, PA6 / PVP@TiO2 composite nanofiber prepared in step 4 is used as raw material to prepare PA6@TiO2 ultra-fine porous nanofiber catalytic filtration membrane by hydrothermal method as follows: PA6 / PVP@TiO2 composite nanofiber obtained in step 4 is placed in a polytetrafluoroethylene-lined stainless steel autoclave and deionized water is added, then the autoclave is placed in a vacuum drying box, heated at 80℃-100℃ for 6h-10h, taken out and naturally cooled to room temperature, washed with deionized water for 3-6 times, and then placed in an oven at 60℃-80℃ for drying for 4h-8h to obtain PA6@TiO2 ultra-fine porous nanofiber catalytic filtration membrane.

[0028] The functional ultra-fine porous nanofiber catalytic filtration membrane preparation method of the application is to prepare an ultra-fine composite nanofiber membrane with good catalytic filtration performance for micron, sub-micron and organic dyes in water. The average diameter of the nanofiber of the nanofiber filtration membrane is 50-80nm, the average porosity is 75-92.5%, the pore size distribution is 0.24-0.45μm, the water flux and the corresponding interception rate are 212.2-241.5L / (m 2 ·h) and 92.5-97.5%, respectively, which can intercept micron and sub-micron pollutants, and has a certain catalytic degradation effect on organic dyes in water, and has good in-situ self-cleaning ability.

[0029] Example 1

[0030] The functional ultra-fine porous nanofiber catalytic filtration membrane preparation method of the application is carried out according to the following steps:

[0031] Step 1, configuration of PA6 / PVP spinning solution: first, the dried PA6 is weighed and added to the formic acid solution, and stirred at a stirring speed of 50 r / min for 4 h, then the PVP powder is weighed and added to the formic acid solution, and continues to be stirred for 10 h until completely dissolved to obtain a mixed solution, and the mixed solution is placed in an ultrasonic cleaner for ultrasonic treatment for 0.5 h to obtain a PA6 / PVP spinning solution with a concentration of 8 wt.%;

[0032] Step 2, using the PA6 / PVP spinning solution configured in step 1 as raw material, PA6 / PVP composite nanofibers are prepared by electrospinning as follows: the prepared PA6 / PVP spinning solution is injected into the liquid storage cylinder of the spinning nozzle of the electrospinning machine, the injection pump is connected to the voltage power supply, the spinning nozzle is placed on one side of the receiving device of the electrospinning machine and the flow rate of the spinning solution is controlled by the injection pump, tin foil paper is placed on the receiving cylinder of the electrospinning machine receiving device, the receiving cylinder rolling switch is turned on, then the single needle spinning is started to spin the spinning solution in the liquid storage cylinder, and a layer of uniform PA6 / PVP composite nanofiber can be obtained on the surface of the tin foil paper; the spinning voltage is 16 KV, the spinning distance is 15 cm, the feeding rate is 0.3 mL / h, the roller speed is 300 rpm, and the collection time is 240 min;

[0033] Step 3, configuration of PA6@TiO2 mixed electrospinning solution: first, the PA6 solid is weighed and added to the formic acid solution, and stirred at a stirring speed of 50 r / min for 3 h, then TiO2 is dissolved in the formic acid solution, and magnetically stirred at 40℃ for 12 h until TiO2 is completely dissolved, finally ultrasonic treatment for 0.5 h; the mass concentration of PA6 in the PA6@TiO2 mixed electrospinning solution is 4 wt.%, and the mass concentration of TiO2 is 4.5 wt.%;

[0034] Step 4, PA6 / PVP@TiO2 composite nanofibers were prepared by electrospinning method using PA6 / PVP composite nanofibers obtained in step 2 and PA6@TiO2 mixed electrospinning liquid obtained in step 2 as raw materials, which was carried out as follows: PA6 / PVP@TiO2 composite nanofibers were prepared by electrospinning method as follows: the prepared PA6@TiO2 mixed electrospinning liquid was injected into the liquid storage cylinder of the electrospinning machine, the injection pump was connected to the voltage power supply, the spinning nozzle was placed on the left side of the receiving device of the electrospinning machine and the flow rate of the spinning liquid was controlled by the injection pump, the PA6 / PVP composite nanofibers prepared in the step were placed on the receiving cylinder of the electrospinning machine receiving device, the receiving cylinder rolling switch was turned on, and then the single needle spinning was started to electrospun the spinning liquid in the liquid storage cylinder, and a uniform layer of PA6 / PVP@TiO2 composite nanofibers was obtained; the voltage of electrospinning was 25KV, the distance of electrospinning was 15cm, the feeding rate was 2.5mL / h, the rotating speed of the cylinder was 300rpm, and the collection time was 480min;

[0035] Step 5, PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane was prepared by hydrothermal method using PA6 / PVP@TiO2 composite nanofibers prepared in step 4 as raw materials, which was carried out as follows: the PA6 / PVP@TiO2 composite nanofibers obtained in step 4 were placed in a polytetrafluoroethylene lined stainless steel autoclave and deionized water was added, then the autoclave was placed in a vacuum drying oven, heated at 80℃ for 10h, then taken out and naturally cooled to room temperature, then washed with deionized water for 3 times, and then placed in a drying oven at 60℃ for 8h to obtain PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane.

[0036] The average diameter of the nanofibers of the nanofiber filtration membrane is 60nm, the average porosity is 92.5%, the average pore size is 0.24μm, the water flux and the corresponding interception rate reach 241.5L / (m 2 ·h) and 97.5% respectively, micrometer and submicron pollutants can be intercepted, and the organic dye in water has a certain catalytic degradation effect, and has good in-situ self-cleaning ability.

[0037] Example 2

[0038] The preparation method of the functional ultrafine porous nanofiber catalytic filtration membrane of the application is carried out according to the following steps:

[0039] Step 1, configuration of PA6 / PVP spinning solution: first, the dried PA6 is weighed and added to the formic acid solution, and stirred at a stirring speed of 80 r / min for 2 h, then the PVP powder is weighed and added to the formic acid solution, and continues to be stirred for 20 h until completely dissolved to obtain a mixed solution, and the mixed solution is placed in an ultrasonic cleaner for ultrasonic treatment for 2 h to obtain a PA6 / PVP spinning solution with a concentration of 12 wt.%;

[0040] Step 2, using the PA6 / PVP spinning solution prepared in step 1 as raw material, PA6 / PVP composite nanofibers are prepared by electrospinning as follows: the prepared PA6 / PVP spinning solution is injected into the liquid storage cylinder of the spinning nozzle of the electrospinning machine, the injection pump is connected to the voltage power supply, the spinning nozzle is placed on the left side of the receiving device of the electrospinning machine and the flow rate of the spinning solution is controlled by the injection pump, tin foil paper is placed on the receiving cylinder of the receiving device of the electrospinning machine, the receiving cylinder rolling switch is turned on, then the single needle spinning is started to spin the spinning solution in the liquid storage cylinder, and a layer of uniform PA6 / PVP composite nanofibers can be obtained on the surface of the tin foil paper; the spinning voltage is 22KV, the spinning distance is 20cm, the feeding rate is 1.5mL / h, and the collection time is 480min;

[0041] Step 3, configuration of PA6@TiO2 mixed electrospinning solution: first, PA6 solid is weighed and added to the formic acid solution, and stirred at a stirring speed of 80 r / min for 2 h, then TiO2 is dissolved in the formic acid solution, and magnetically stirred at 60℃ for 8 h until TiO2 is completely dissolved, and finally ultrasonic treatment for 2 h; the mass concentration of PA6 in the PA6@TiO2 mixed electrospinning solution is 10 wt.% and the mass concentration of TiO2 is 8.5 wt.%;

[0042] Step 4, using the PA6 / PVP composite nanofibers obtained in step 2 and the PA6@TiO2 mixed electrospinning solution obtained in step 2 as raw materials, PA6 / PVP@TiO2 composite nanofibers are prepared by electrospinning as follows: PA6 / PVP@TiO2 composite nanofibers are prepared by electrospinning as follows: the prepared PA6@TiO2 mixed electrospinning solution is injected into the liquid storage cylinder of the spinning nozzle of the electrospinning machine, the injection pump is connected to the voltage power supply, the spinning nozzle is placed on the left side of the receiving device of the electrospinning machine and the flow rate of the spinning solution is controlled by the injection pump, the PA6 / PVP composite nanofibers prepared in step are placed on the receiving cylinder of the receiving device of the electrospinning machine, the receiving cylinder rolling switch is turned on, then the single needle spinning is started to electrospun the spinning solution in the liquid storage cylinder, and a layer of uniform PA6 / PVP@TiO2 composite nanofibers can be obtained; the voltage of the electrospinning is 30KV, the distance of the electrospinning is 20cm, the feeding rate is 2.5mL / h, the rotating speed of the cylinder is 550rpm, and the collection time is 480min;

[0043] Step 5, PA6@TiO2 ultra-fine porous nanofiber catalytic filtration membrane is prepared by using PA6 / PVP@TiO2 composite nanofiber prepared in step 4 as raw material by hydrothermal method: PA6 / PVP@TiO2 composite nanofiber obtained in step 4 is placed in a polytetrafluoroethylene-lined stainless steel autoclave and deionized water is added, then the autoclave is placed in a vacuum drying box, heated at 100 DEG C for 6 h, taken out and naturally cooled to room temperature, washed with deionized water for 6 times, and then placed in an oven at 80 DEG C for drying for 4 h to obtain PA6@TiO2 ultra-fine porous nanofiber catalytic filtration membrane.

[0044] The average diameter of the nanofiber filtration membrane is 80 nm, the average porosity is 75%, the average pore size is 0.45 μm, the water flux and the corresponding interception rate reach 212.2 L / (m 2 ·h) and 92.5%, respectively, micrometer and sub-micrometer pollutants can be intercepted, and the organic dye in water has a certain catalytic degradation effect, and has good in-situ self-cleaning ability.

[0045] Example 3

[0046] The preparation method of the functional ultra-fine porous nanofiber catalytic filtration membrane of the application is specifically implemented according to the following steps:

[0047] Step 1, preparing PA6 / PVP spinning solution: first, weigh the dried PA6 and add it into formic acid solution, and stir at a stirring speed of 65 r / min for 3 h, then weigh the PVP powder and add it into formic acid solution, and continue to stir for 15 h until completely dissolved to obtain a mixed solution, and then place the mixed solution in an ultrasonic cleaner and ultrasonic for 1 h to obtain a PA6 / PVP spinning solution with a concentration of 10 wt.%;

[0048] Step 2, PA6 / PVP composite nanofiber is prepared by using PA6 / PVP spinning solution prepared in step 1 as raw material by electrospinning: the prepared PA6 / PVP spinning solution is injected into the liquid storage cylinder of the spinning nozzle of the electrospinning machine, the injection pump is connected to the voltage power supply, the spinning nozzle is placed on one side of the receiving device of the electrospinning machine and the flow rate of the spinning solution is controlled by the injection pump, tin foil paper is placed on the receiving cylinder of the receiving device, the receiving cylinder rolling switch is turned on, and then a single needle spinning is started to spin the spinning solution in the liquid storage cylinder, and a layer of uniform PA6 / PVP composite nanofiber can be obtained on the surface of the tin foil paper; the spinning voltage is 19 KV, the spinning distance is 18 cm, the feeding rate is 0.9 mL / h, the roller speed is 400 rpm, and the collection time is 300 min;

[0049] Step 3, PA6@TiO2 mixed e-jet liquid was prepared as follows: PA6 solid was weighed and added into formic acid solution, and stirred at a stirring speed of 65 r / min for 2.5 h; TiO2 was weighed and dissolved in formic acid solution, and stirred at a stirring speed of 50 r / min for 10 h until TiO2 was completely dissolved; then ultrasonic treatment was performed for 1 h; the mass concentration of PA6 in the PA6@TiO2 mixed e-jet liquid was 7 wt.%, and the mass concentration of TiO2 was 6.5 wt.%.

[0050] Step 4, PA6 / PVP@TiO2 composite nanofiber was prepared by electrospinning method using PA6 / PVP composite nanofiber obtained in step 2 and PA6@TiO2 mixed e-jet liquid obtained in step 2 as raw materials, which was performed as follows: PA6 / PVP@TiO2 composite nanofiber was prepared by electrospinning method as follows: the prepared PA6@TiO2 mixed e-jet liquid was injected into the liquid storage cylinder of the spinning nozzle of the electrospinning machine, the injection pump was connected to the voltage power supply, the spinning nozzle was placed on the left side of the receiving device of the electrospinning machine and the flow rate of the spinning liquid was controlled by the injection pump, the PA6 / PVP composite nanofiber prepared in step 2 was placed on the receiving cylinder of the receiving device of the electrospinning machine, the receiving cylinder rolling switch was turned on, and then the single needle spinning was started to electrospun the spinning liquid in the liquid storage cylinder, so that a uniform layer of PA6 / PVP@TiO2 composite nanofiber was obtained; the voltage of electrospinning was 27 KV, the distance of electrospinning was 18 cm, the feeding rate was 2 mL / h, the rotating speed of the cylinder was 400 rpm, and the collection time was 360 min.

[0051] Step 5, PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane was prepared by hydrothermal method using the PA6 / PVP@TiO2 composite nanofiber prepared in step 4 as raw material, which was performed as follows: the PA6 / PVP@TiO2 composite nanofiber obtained in step 4 was placed in a stainless steel autoclave with a polytetrafluoroethylene liner and deionized water was added, then the autoclave was placed in a vacuum drying box and heated at 90°C for 8 h, then it was taken out and naturally cooled to room temperature, then the nanofiber was washed with deionized water for 4 times and then dried in an oven at 70°C for 6 h to obtain the PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane.

[0052] The average diameter of the nanofiber of the nanofiber filtration membrane was 65 nm, the average porosity was 83.5%, the average pore size was 0.38 μm, the water flux and the corresponding interception rate reached 226.8 L / (m 2 ·h) and 90.5%, respectively, which could intercept micrometer and sub-micrometer pollutants, and had a certain catalytic degradation effect on organic dyes in water, and also had good in-situ self-cleaning ability.

[0053] Example 4

[0054] The application discloses a preparation method of a functional superfine porous nanofiber catalytic filtration membrane.

[0055] Step 1, configuring PA6 / PVP spinning solution: first, the dried PA6 is weighed and added into formic acid solution, and stirred at a stirring speed of 60 r / min for 3.5 h, then the PVP powder is weighed and added into the formic acid solution, and continues to be stirred for 12 h until completely dissolved to obtain a mixed solution, and the mixed solution is placed in an ultrasonic cleaner and ultrasonically treated for 0.5 h-2 h to obtain a PA6 / PVP spinning solution with a concentration of 11.5 wt.%;

[0056] Step 2, the PA6 / PVP spinning solution configured in step 1 is used as raw material to prepare the PA6 / PVP composite nanofiber by electrospinning as follows: the prepared PA6 / PVP spinning solution is injected into a liquid storage cylinder of a spinning nozzle of an electrospinning machine, a voltage power supply is connected to the injection pump, the spinning nozzle is placed on one side of a receiving device of the electrospinning machine and the flow rate of the spinning solution is controlled through the injection pump, a tin foil paper is placed on a receiving cylinder of the receiving device, a receiving cylinder rolling switch is turned on, then a single needle spinning is started to spin the spinning solution in the liquid storage cylinder, and a layer of uniform PA6 / PVP composite nanofiber can be obtained on the surface of the tin foil paper of the receiving cylinder; the spinning voltage is 18 KV, the spinning distance is 16 cm, the feeding rate is 0.8 mL / h, and the collection time is 300 min;

[0057] Step 3, configuring PA6@TiO2 mixed electrospinning solution: first, the PA6 solid is weighed and added into formic acid solution, and stirred at a stirring speed of 70 r / min for 2.5 h, then the TiO2 is dissolved in formic acid solution, and magnetically stirred at 55 DEG C for 9 h until the TiO2 is completely dissolved, finally ultrasonic treatment is carried out for 1.5 h; the mass concentration of PA6 in the PA6@TiO2 mixed electrospinning solution is 8 wt.%, and the mass concentration of TiO2 is 7.5 wt.%;

[0058] Step 4, PA6 / PVP@TiO2 composite nanofibers were prepared by electrospinning method using PA6 / PVP composite nanofibers obtained in step 2 and PA6@TiO2 mixed electrospinning liquid obtained in step 2 as raw materials. The preparation of PA6 / PVP@TiO2 composite nanofibers by electrospinning method was carried out as follows: the prepared PA6@TiO2 mixed electrospinning liquid was injected into the liquid storage cylinder of the electrospinning machine, the injection pump was connected to the voltage power supply, the spinning nozzle was placed on the left side of the receiving device of the electrospinning machine and the flow rate of the spinning liquid was controlled by the injection pump, the PA6 / PVP composite nanofibers prepared in step 2 were placed on the receiving cylinder of the electrospinning machine, the receiving cylinder rolling switch was turned on, and then the single needle spinning was started to electrospun the spinning liquid in the liquid storage cylinder, and a uniform layer of PA6 / PVP@TiO2 composite nanofibers was obtained. The electrospinning voltage was 28KV, the electrospinning distance was 17cm, the feeding rate was 2.0mL / h, the roller speed was 450rpm, and the collection time was 320min.

[0059] Step 5, PA6@TiO2 ultra-fine porous nanofiber catalytic filtration membrane was prepared by hydrothermal method using PA6 / PVP@TiO2 composite nanofibers prepared in step 4 as raw materials. The PA6 / PVP@TiO2 composite nanofibers obtained in step 4 were placed in a polytetrafluoroethylene-lined stainless steel autoclave and deionized water was added, then the autoclave was placed in a vacuum drying box and heated at 90℃ for 7h, then it was taken out and naturally cooled to room temperature, then the nanofibers were washed with deionized water for 4 times and then placed in a drying oven at 65℃ for 4.5h to obtain PA6@TiO2 ultra-fine porous nanofiber catalytic filtration membrane.

[0060] The average diameter of the nanofiber filtration membrane was 75nm, the average porosity was 80.5%, the average pore size was 0.42μm, the water flux and the corresponding interception rate reached 216.1L / (m 2 ·h) and 92.8%, respectively, which could intercept micrometer and sub-micrometer pollutants, and had a certain catalytic degradation effect on organic dyes in water, and also had good in-situ self-cleaning ability.

Claims

1. A method for preparing a functional ultrafine porous nanofiber catalytic filtration membrane, characterized in that, The specific implementation shall be carried out in the following manner: Step 1: Prepare PA6 / PVP spinning solution; Step 2: Using the PA6 / PVP spinning solution prepared in Step 1 as raw material, PA6 / PVP composite nanofibers are prepared by electrospinning. Step 3: Prepare the PA6@TiO2 mixed electro-injection fluid; Step 4: Using the PA6 / PVP composite nanofibers obtained in Step 2 and the PA6@TiO2 mixed electrospray liquid obtained in Step 3 as raw materials, PA6 / PVP@TiO2 composite nanofibers are prepared by electrostatic spraying. Step 5: Using the PA6 / PVP@TiO2 composite nanofibers obtained in Step 4 as raw materials, PA6@TiO2 ultrafine porous nanofiber catalytic filtration membranes are prepared by hydrothermal method. In step 1, the PA6 / PVP spinning solution is prepared as follows: First, dry PA6 is weighed and added to formic acid solution, and stirred at a stirring speed of 50 r / min - 80 r / min for 2h-4h. Then, PVP powder is weighed and added to formic acid solution, and stirred for 10h-20h until completely dissolved to obtain a mixed solution. The mixed solution is placed in an ultrasonic cleaner and sonicated for 0.5h-2h to obtain a PA6 / PVP spinning solution with a concentration of 8wt.%-12wt.%. In step 2, the preparation of PA6 / PVP composite nanofibers by electrospinning is as follows: The prepared PA6 / PVP spinning solution is injected into the reservoir of the spinning nozzle of the electrospinning machine. The injection pump is connected to a power supply. The spinning nozzle is placed on one side of the receiving device of the electrospinning machine, and the flow rate of the spinning solution is controlled by the injection pump. Tin foil is placed on the receiving cylinder of the receiving device of the electrospinning machine. The rolling switch of the receiving cylinder is turned on, and then the single-needle spinning is started to spin the spinning solution in the reservoir. A uniform layer of PA6 / PVP composite nanofibers can be obtained on the surface of the tin foil in the receiving cylinder. The spinning voltage is 16KV-22KV, the spinning distance is 15cm-20cm, the feeding rate is 0.3mL / h-1.5mL / h, the drum speed is 300rpm-550rpm, and the collection time is 240min-480min. In step 3, the preparation of the PA6@TiO2 mixed electrospray solution is as follows: First, weigh solid PA6 and add it to formic acid solution, and stir at a stirring speed of 50 r / min-80 r / min for 2-3 hours. Then, weigh TiO2 and dissolve it in formic acid solution, and magnetically stir at 40℃-60℃ for 8-12 hours until TiO2 is completely dissolved. Finally, sonicate for 0.5-2 hours. The mass concentration of PA6 in the PA6@TiO2 mixed electrospray solution is 4wt.%-10wt.%, and the mass concentration of TiO2 is 4.5wt.%-8.5wt.%. In step 4, the preparation of PA6 / PVP@TiO2 composite nanofibers using electrostatic spraying is carried out as follows: The prepared PA6@TiO2 mixed electrospray solution is injected into the storage tank of the spinning nozzle of the electrospinning machine. The injection pump is connected to a power supply. The spinning nozzle is placed on the left side of the receiving device of the electrospinning machine, and the flow rate of the spinning solution is controlled by the injection pump. The PA6 / PVP composite nanofibers prepared in the previous step are placed on the receiving tank of the receiving device of the electrospinning machine. The receiving tank rolling switch is turned on, and then the single-needle spinning is started to electrostatically spray the spinning solution in the storage tank to obtain a uniform layer of PA6 / PVP@TiO2 composite nanofibers. The electrospraying voltage is 25 KV-30 KV, the electrospraying distance is 15 cm-20 cm, the feeding rate is 1.0 mL / h-2.5 mL / h, the drum speed is 300 rpm-550 rpm, and the collection time is 240 min-480 min. In step 5, the PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane is prepared by hydrothermal method as follows: The PA6 / PVP@TiO2 composite nanofibers obtained in step 4 are placed in a stainless steel autoclave lined with polytetrafluoroethylene and deionized water is added. Then, the autoclave is placed in a vacuum drying oven and heated at 80°C-100°C for 6-10 hours. After being removed and naturally cooled to room temperature, the nanofibers are washed with deionized water 3-6 times and then dried in an oven at 60°C-80°C for 4-8 hours to obtain the PA6@TiO2 ultrafine porous nanofiber catalytic filtration membrane.

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