Preparation and application of 3D porous nanocellulose aerogel electret materials for radioactive aerosol purification

Abstract

The application discloses a kind of preparation and application of 3D porous nanocellulose aerogel electret material for radioactive aerosol purification, comprising: preparation of dialdehyde cellulose nanofiber and preparation of ethyl cellulose nanofiber;Dialdehyde cellulose nanofiber is dispersed with ethyl cellulose nanofiber in tertiary butanol aqueous solution to form fiber suspension, and it is transferred to template, freeze-drying, and 3D porous nanocellulose aerogel is obtained;3D porous nanocellulose aerogel is heat treated in aniline steam, and modified 3D porous nanocellulose aerogel is obtained, then it is corona polarized, and 3D porous nanocellulose aerogel electret material is obtained.The 3D porous nanocellulose aerogel electret material of the application has certain electricity storage performance, the surface potential of electret nanofiber aerogel is tested, and the surface potential value is still higher than 0.27kV after 420min, and its dust capacity is good, purification performance is high, with good application prospect.

Description

Technical Field

[0001] This invention relates to the field of functional polymer material preparation, specifically to the preparation and application of a 3D porous nanocellulose aerogel electret material for the purification of radioactive aerosols. Background Technology

[0002] The preparation of electret materials mainly uses petroleum-based polymers such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polyethylene glycol as raw materials, which are difficult to biodegrade and become secondary pollutants after replacement. Therefore, developing an electret fiber material that is both economically efficient and environmentally friendly has broad application prospects. Cellulose nanofibers not only possess the morphology of nanofibers but also have the advantages of cellulose's renewability and biodegradability. Furthermore, cellulose fibers, after chemical grafting modification, exhibit excellent charge trapping ability and charge storage stability. Therefore, their use in preparing biomass-based electret nanofiber aerogels has broad application prospects. However, due to the large number of polar functional groups such as carboxyl and hydroxyl groups on the surface of nanocellulose fibers, strong hydrogen bonding between fibers during aerogel formation makes them prone to self-assembly, forming a layered porous structure with "nanopaper" pore walls. This non-connected porous structure is not conducive to airflow and hinders the improvement of the purification efficiency of fiber aerogels. Therefore, preventing the self-assembly tendency of cellulose nanofibers, improving the pore structure of fiber aerogels, and enhancing the electret and purification performance of fiber materials are of unparalleled significance. Summary of the Invention

[0003] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0004] To achieve these objectives and other advantages according to the present invention, a method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification is provided, comprising the following steps:

[0005] Step 1: Preparation of dialdehyde cellulose nanofibers: cellulose powder is mixed with sodium periodate, and dialdehyde cellulose nanofibers are obtained by combining a ball mill and an ultrasonic crusher.

[0006] Step 2, Preparation of ethyl cellulose nanofibers: Ethyl cellulose is dissolved in N,N-dimethylacetamide solvent and electrospinned to obtain ethyl cellulose nanofibers;

[0007] Step 3: Preparation of 3D porous nanocellulose aerogel: Dialdehyde cellulose nanofibers and ethyl cellulose nanofibers are dispersed in tert-butanol aqueous solution to form a fiber suspension, which is then transferred to a template and freeze-dried to obtain 3D porous nanocellulose aerogel.

[0008] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel is heat-treated in aniline vapor to obtain modified 3D porous nanocellulose aerogel; the modified 3D porous nanocellulose aerogel is then subjected to corona polarization to obtain 3D porous nanocellulose aerogel electret material.

[0009] Preferably, the process of step one is as follows: cellulose powder is mixed with sodium periodate and H2SO4 solution is added. The mixture is ball-milled in a ball mill for 2-4 hours. Then, it is washed repeatedly with deionized water until neutral. Finally, it is dispersed in deionized water and ultrasonically broken up using an ultrasonic disruptor. The upper colloidal liquid is collected by centrifugation at a speed of 2000-3000 r / min to obtain a dialdehyde cellulose nanofiber suspension.

[0010] Preferably, in step one, the solvent used for ball milling is an H2SO4 solution with pH = 3-5, the mass-to-volume ratio of cellulose powder to H2SO4 solution is 1g:10-20mL, the ball milling speed is 300-500r / min, and the ball milling time is 2-4h; the ultrasonic crusher has a crushing power of 200-400W, and the ultrasonic crushing time is 3-6h.

[0011] Preferably, in step one, the mass ratio of cellulose powder to sodium periodate is 1:1 to 3.

[0012] Preferably, in step two, the solid-liquid ratio of ethyl cellulose to N,N-dimethylacetamide is 1g:7-10mL, the electrospinning voltage is 11-15kV, the distance from the needle tip to the receiving plate is 13-17cm, the spinning temperature is 15-35℃, and the spinning air humidity is ≤20-50%RH.

[0013] Preferably, in step two, the prepared ethyl cellulose nanofibers are processed as follows: the ethyl cellulose nanofibers are placed in the reaction chamber of a low-temperature plasma treatment instrument and treated with NH3 low-temperature plasma. The discharge time is set to 90-120s, the discharge power is 200-300W, and the NH3 gas inlet is 150-200sccm to obtain the treated ethyl cellulose nanofibers.

[0014] Preferably, in step three, the mass ratio of dialdehyde cellulose nanofibers to ethyl cellulose nanofibers is 0.1–3:0.1–3, the concentration of tert-butanol aqueous solution is 0–30 wt%, the pre-freezing temperature is -20–-190°C, the pre-freezing time is 4–12 h, the freeze-drying temperature is -40–-60°C, the freeze-drying time is 24–48 h, and the template material is plastic or stainless steel.

[0015] Preferably, in step three, the total mass concentration of the fiber suspension is 0.5% to 2.5%.

[0016] Preferably, in step three, the obtained 3D porous nanocellulose aerogel is irradiated under an excimer ultraviolet lamp at a distance of 1-5 cm for a duration of 3-5 min to obtain the irradiated 3D porous nanocellulose aerogel.

[0017] Preferably, in step four, the ratio of 3D porous nanocellulose aerogel to aniline is 0.5–2.5 g: 0.5–2.5 mL, the heat treatment temperature is 90–130 °C, and the heat treatment time is 1–7 h.

[0018] Preferably, in step four, the corona polarization conditions for the modified 3D porous nanocellulose aerogel are: polarization voltage of 5-15kV, needle-plate distance of 1-4cm, polarization time of 5-30min, polarization temperature of 15-35℃, and polarization air humidity of 15-40%RH.

[0019] The present invention also provides an application of the 3D porous nanocellulose aerogel electret material prepared by the preparation method described above in the purification of radioactive aerosols, wherein the 3D porous nanocellulose aerogel electret material is placed in an environment containing radioactive aerosols to achieve the purification of radioactive aerosols.

[0020] This invention modulates the pore structure of 3D porous nanocellulose aerogel electret material by adding ethyl cellulose nanofibers and tert-butanol solution to a dialdehyde cellulose nanofiber suspension and adjusting the pre-freezing temperature and the total concentration of the cellulose nanofiber suspension during the preparation process. This improves the charge storage density and charge storage stability of the 3D porous nanocellulose aerogel, thereby enhancing the electret performance and purification performance of the material for aerosol particles.

[0021] The present invention has at least the following beneficial effects:

[0022] (1) The materials used in this invention are natural polymer materials and their derivatives (cellulose powder and ethyl cellulose), which have the advantages of low cost and biodegradability.

[0023] (2) The 3D porous nanocellulose aerogel electret material prepared by the method of the present invention has certain energy storage performance. The surface potential of the electret nanocellulose aerogel was tested by an EST102 type vibrating capacitive electrometer. After 420 min, its surface potential value was still higher than 0.27kV. It also has good dust holding capacity and high purification performance, and has good application prospects.

[0024] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached image description:

[0025] Figure 1 The surface potential decay diagrams are shown for the 3D porous nanocellulose aerogel electret materials prepared in Examples 1, 2, and 3 of this invention and the 3D porous nanocellulose aerogel electret material prepared in Comparative Example 1.

[0026] Figure 2 The surface potential decay diagrams are for the 3D porous nanocellulose aerogel electret materials prepared in Examples 4, 5, 6, and 7 of this invention and the 3D porous nanocellulose aerogel electret materials prepared in Comparative Example 1.

[0027] Figure 3 The purification time diagrams are for the 3D porous nanocellulose aerogel electret materials prepared in Examples 1, 2, and 3 of this invention and the 3D porous nanocellulose aerogel electret materials prepared in Comparative Example 1.

[0028] Figure 4 The purification time diagrams are for the 3D porous nanocellulose aerogel electret materials prepared in Examples 4, 5, 6, and 7 of this invention and the 3D porous nanocellulose aerogel electret materials prepared in Comparative Example 1.

[0029] Figure 5 The purification time diagrams are for the 3D porous nanocellulose aerogel electret materials prepared in Examples 1, 8, 9, and 10 of this invention and the 3D porous nanocellulose aerogel electret materials prepared in Comparative Example 1.

[0030] Figure 6 SEM images of the 3D porous nanocellulose aerogel electret material prepared in Example 1 and the 3D porous nanocellulose aerogel electret material prepared in Comparative Example 1 of this invention.

[0031] Figure 7 This is a SEM image of the 3D porous nanocellulose aerogel electret material prepared in Comparative Example 1 of this invention. Detailed implementation method:

[0032] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0033] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not imply the presence or addition of one or more other elements or combinations thereof.

[0034] The air purification performance measurement method of the 3D porous nanocellulose aerogel electret material prepared in this invention is as follows: the test chamber has dimensions of 70*45*50cm, a smoke generator is used to simulate radioactive aerosols (R-PM2.5), and the initial mass concentration of R-PM2.5 is controlled at 999ug / m³ by dilution with fresh air. 3 A self-made 3D porous nanocellulose aerogel electret material was used to replace the filter material in an air purifier (Philips CP50, placed in the test chamber) to capture R-PM2.5. An air quality detector (AirNow, placed in the test chamber) was used to detect the mass concentration of R-PM2.5, recording the concentration from 999 ug / m³. 3 The purification time required to reduce to 0 was used to measure the purification capacity of 3D porous nanocellulose aerogel electret materials.

[0035] Example 1:

[0036] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0037] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0038] Step 2, Preparation of ethyl cellulose nanofibers: 1g of ethyl cellulose was dissolved in 10mL of N,N-dimethylacetamide solvent, and ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13kV, distance from needle tip (liquid outlet of electrospinning) to receiving plate of 15cm, spinning temperature of 35℃, and spinning air humidity of 20%RH.

[0039] Step 3, Preparation of 3D porous nanocellulose aerogel: Measure a suspension containing 1.0g of dialdehyde cellulose nanofibers, and add deionized water and 10mL of tert-butanol to a total solvent volume of 100mL. Then disperse 0.5g of ethyl cellulose nanofibers in the dialdehyde cellulose nanofiber suspension and transfer it to a plastic template. Pre-freeze at -40℃ for 6h. After freezing and shaping, transfer it to a freeze dryer at -50℃ and dry for 36h to obtain 3D porous nanocellulose aerogel.

[0040] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel prepared in Step 3 is placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel is placed in a corona polarization device, the polarization voltage is adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material is corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0041] The surface potential of the 3D porous nanocellulose aerogel electret material prepared in this embodiment was 0.27 kV after 420 min, which reduced the surface potential of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 14 minutes.

[0042] Figure 6 The image shows a SEM image of the 3D porous nanocellulose aerogel electret material prepared in Example 1 of this invention. As can be seen from the image, the electret material has an open cellular porous structure with fibrous mesh walls.

[0043] Example 2:

[0044] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0045] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0046] Step 2, Preparation of ethyl cellulose nanofibers: 1g of ethyl cellulose was dissolved in 10mL of N,N-dimethylacetamide solvent, and ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13kV, distance from needle tip to receiving plate of 15cm, spinning temperature of 35℃, and spinning air humidity of 20%RH.

[0047] Step 3: Preparation of 3D porous nanocellulose aerogel: Measure a suspension containing 0.75g of dialdehyde cellulose nanofibers, and add deionized water and 10mL of tert-butanol to make the total solvent volume 100mL. Then disperse 0.75g of ethyl cellulose nanofibers in the dialdehyde cellulose nanofiber suspension and transfer it to a plastic template. Pre-freeze at -40℃ for 6h. After it freezes and solidifies, transfer it to a freeze dryer at -50℃ and dry for 36h to obtain 3D porous nanocellulose aerogel.

[0048] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel prepared in Step 3 is placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel is placed in a corona polarization device, the polarization voltage is adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material is corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0049] The surface potential of the 3D porous nanocellulose aerogel electret material prepared in this embodiment was 0.35 kV after 420 min, which reduced the surface potential of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 11 minutes.

[0050] Example 3:

[0051] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0052] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0053] Step 2, Preparation of ethyl cellulose nanofibers: 1g of ethyl cellulose was dissolved in 10mL of N,N-dimethylacetamide solvent, and ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13kV, distance from needle tip to receiving plate of 15cm, spinning temperature of 35℃, and spinning air humidity of 20%RH.

[0054] Step 3: Preparation of 3D porous nanocellulose aerogel: Measure out a suspension containing 0.5g of dialdehyde cellulose nanofibers, and add deionized water and 10mL of tert-butanol to make the total solvent volume 100mL. Then disperse 1g of ethyl cellulose nanofibers in the dialdehyde cellulose nanofiber suspension and transfer it to a plastic template. Pre-freeze at -40℃ for 6h. After it freezes and solidifies, transfer it to a freeze dryer at -50℃ and dry for 36h to obtain 3D porous nanocellulose aerogel.

[0055] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel prepared in Step 3 is placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel is placed in a corona polarization device, the polarization voltage is adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material is corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0056] The surface potential of the 3D porous nanocellulose aerogel electret material prepared in this embodiment was 0.47 kV after 420 min, which reduced the surface potential of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 13 minutes.

[0057] Example 4:

[0058] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0059] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0060] Step 2, Preparation of ethyl cellulose nanofibers: 1g of ethyl cellulose was dissolved in 10mL of N,N-dimethylacetamide solvent, and ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13kV, distance from needle tip to receiving plate of 15cm, spinning temperature of 35℃, and spinning air humidity of 20%RH.

[0061] Step 3: Preparation of 3D porous nanocellulose aerogel: Measure out a suspension containing 0.5g of dialdehyde cellulose nanofibers, and add deionized water and 10mL of tert-butanol to make the total solvent volume 100mL. Then disperse 1g of ethyl cellulose nanofibers in the dialdehyde cellulose nanofiber suspension and transfer it to a plastic template. Pre-freeze at -20℃ for 6h. After it freezes and solidifies, transfer it to a freeze dryer at -50℃ and dry for 36h to obtain 3D porous nanocellulose aerogel.

[0062] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel prepared in Step 3 is placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel is placed in a corona polarization device, the polarization voltage is adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material is corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0063] The surface potential of the 3D porous nanocellulose aerogel electret material prepared in this embodiment was 0.36 kV after 420 min, which reduced the surface potential of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 14 minutes.

[0064] Example 5:

[0065] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0066] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0067] Step 2, Preparation of ethyl cellulose nanofibers: 1g of ethyl cellulose was dissolved in 10mL of N,N-dimethylacetamide solvent, and ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13kV, distance from needle tip to receiving plate of 15cm, spinning temperature of 35℃, and spinning air humidity of 20%RH.

[0068] Step 3: Preparation of 3D porous nanocellulose aerogel: Measure out a suspension containing 0.5g of dialdehyde cellulose nanofibers, and add deionized water and 10mL of tert-butanol to make the total solvent volume 100mL. Then disperse 1g of ethyl cellulose nanofibers in the dialdehyde cellulose nanofiber suspension and transfer it to a plastic template. Pre-freeze at -80℃ for 6h. After it freezes and solidifies, transfer it to a freeze dryer at -50℃ and dry for 36h to obtain 3D porous nanocellulose aerogel.

[0069] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel prepared in Step 3 is placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel is placed in a corona polarization device, the polarization voltage is adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material is corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0070] The surface potential of the 3D porous nanocellulose aerogel electret material prepared in this embodiment was 0.57 kV after 420 min, which reduced the surface potential of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 15 minutes.

[0071] Example 6:

[0072] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0073] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0074] Step 2, Preparation of ethyl cellulose nanofibers: 1g of ethyl cellulose was dissolved in 10mL of N,N-dimethylacetamide solvent, and ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13kV, distance from needle tip to receiving plate of 15cm, spinning temperature of 35℃, and spinning air humidity of 20%RH.

[0075] Step 3: Preparation of 3D porous nanocellulose aerogel: Measure out a suspension containing 0.5g of dialdehyde cellulose nanofibers, and add deionized water and 10mL of tert-butanol to make the total solvent volume 100mL. Then disperse 1g of ethyl cellulose nanofibers in the dialdehyde cellulose nanofiber suspension and transfer it to a stainless steel template. Pre-freeze at -190℃ for 6h. After it freezes and solidifies, transfer it to a freeze dryer at -50℃ and dry for 36h to obtain 3D porous nanocellulose aerogel.

[0076] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel prepared in Step 3 is placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel is placed in a corona polarization device, the polarization voltage is adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material is corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0077] The surface potential of the 3D porous nanocellulose aerogel electret material prepared in this embodiment was 0.67 kV after 420 min, which reduced the surface potential of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3Reduced to 0ug / m 3 The required purification time is 16 minutes.

[0078] Example 7:

[0079] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0080] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0081] Step 2, Preparation of ethyl cellulose nanofibers: 1g of ethyl cellulose was dissolved in 10mL of N,N-dimethylacetamide solvent, and ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13kV, distance from needle tip to receiving plate of 15cm, spinning temperature of 35℃, and spinning air humidity of 20%RH.

[0082] Step 3: Preparation of 3D porous nanocellulose aerogel: Measure a suspension containing 0.33g of dialdehyde cellulose nanofibers, and add deionized water and 10mL of tert-butanol to make the total solvent volume 100mL. Then disperse 0.67g of ethyl cellulose nanofibers in the dialdehyde cellulose nanofiber suspension and transfer it to a plastic template. Pre-freeze at -40℃ for 6h. After it freezes and solidifies, transfer it to a freeze dryer at -50℃ and dry for 36h to obtain 3D porous nanocellulose aerogel.

[0083] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel prepared in Step 3 is placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel is placed in a corona polarization device, the polarization voltage is adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material is corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0084] The surface potential of the 3D porous nanocellulose aerogel electret material prepared in this embodiment was 0.40 kV after 420 min, which reduced the surface potential of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 14 minutes.

[0085] Example 8:

[0086] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0087] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0088] Step 2: Preparation of ethyl cellulose nanofibers: 1 g of ethyl cellulose was dissolved in 10 mL of N,N-dimethylacetamide solvent. Ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13 kV, distance from the needle tip (the outlet of the electrospinning solution) to the receiving plate of 15 cm, spinning temperature of 35 °C, and spinning air humidity of 20% RH. The ethyl cellulose nanofibers were then placed in the reaction chamber of a low-temperature plasma treatment instrument and treated with NH3 low-temperature plasma. The discharge time was set to 120 s, the discharge power to 250 W, and the NH3 inlet flow rate to 150 sccm, resulting in the treated ethyl cellulose nanofibers.

[0089] Step 3, Preparation of 3D porous nanocellulose aerogel: Measure a suspension containing 1.0g of dialdehyde cellulose nanofibers, and add deionized water and 10mL of tert-butanol to a total solvent volume of 100mL. Then disperse 0.5g of treated ethyl cellulose nanofibers in the dialdehyde cellulose nanofiber suspension and transfer it to a plastic template. Pre-freeze at -40℃ for 6h. After freezing and shaping, transfer it to a freeze dryer at -50℃ and dry for 36h to obtain 3D porous nanocellulose aerogel.

[0090] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel prepared in Step 3 is placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel is placed in a corona polarization device, the polarization voltage is adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material is corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0091] The 3D porous nanocellulose aerogel electret material prepared in this embodiment can be used as a filter material to reduce the particle size of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 8 minutes.

[0092] Example 9:

[0093] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0094] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0095] Step 2, Preparation of ethyl cellulose nanofibers: 1g of ethyl cellulose was dissolved in 10mL of N,N-dimethylacetamide solvent, and ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13kV, distance from needle tip (liquid outlet of electrospinning) to receiving plate of 15cm, spinning temperature of 35℃, and spinning air humidity of 20%RH.

[0096] Step 3: Preparation of 3D porous nanocellulose aerogel: A suspension containing 1.0g of dialdehyde cellulose nanofibers was measured, and deionized water and 10mL of tert-butanol were added to bring the total solvent volume to 100mL. Then, 0.5g of ethyl cellulose nanofibers were dispersed in the dialdehyde cellulose nanofiber suspension and transferred to a plastic template. The template was pre-frozen at -40℃ for 6 hours. After freezing and solidification, the template was transferred to a freeze dryer at -50℃ and dried for 36 hours to obtain 3D porous nanocellulose aerogel. The obtained 3D porous nanocellulose aerogel was irradiated under an excimer ultraviolet lamp at a distance of 2cm for 5min to obtain the irradiated 3D porous nanocellulose aerogel.

[0097] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The irradiated 3D porous nanocellulose aerogel prepared in Step 3 was placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel was placed in a corona polarization device, the polarization voltage was adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material was corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0098] The 3D porous nanocellulose aerogel electret material prepared in this embodiment can be used as a filter material to reduce the particle size of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 7 minutes.

[0099] Example 10:

[0100] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0101] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0102] Step 2: Preparation of ethyl cellulose nanofibers: 1 g of ethyl cellulose was dissolved in 10 mL of N,N-dimethylacetamide solvent. Ethyl cellulose nanofibers were obtained by electrospinning under the following conditions: electrospinning voltage of 13 kV, distance from the needle tip (the outlet of the electrospinning solution) to the receiving plate of 15 cm, spinning temperature of 35 °C, and spinning air humidity of 20% RH. The ethyl cellulose nanofibers were then placed in the reaction chamber of a low-temperature plasma treatment instrument and treated with NH3 low-temperature plasma. The discharge time was set to 120 s, the discharge power to 250 W, and the NH3 inlet flow rate to 150 sccm, resulting in the treated ethyl cellulose nanofibers.

[0103] Step 3: Preparation of 3D porous nanocellulose aerogel: A suspension containing 1.0 g of dialdehyde cellulose nanofibers was weighed and supplemented with deionized water and 10 mL of tert-butanol to a total solvent volume of 100 mL. Then, 0.5 g of treated ethyl cellulose nanofibers were dispersed in the dialdehyde cellulose nanofiber suspension and transferred to a plastic template. The template was pre-frozen at -40℃ for 6 h. After freezing and solidification, the template was transferred to a freeze dryer at -50℃ and dried for 36 h to obtain a 3D porous nanocellulose aerogel. The obtained 3D porous nanocellulose aerogel was irradiated under an excimer ultraviolet lamp at a distance of 2 cm for 5 min to obtain an irradiated 3D porous nanocellulose aerogel.

[0104] Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The irradiated 3D porous nanocellulose aerogel prepared in Step 3 was placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel was placed in a corona polarization device, the polarization voltage was adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material was corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0105] The 3D porous nanocellulose aerogel electret material prepared in this embodiment can be used as a filter material to reduce the particle size of radioactive aerosols (R-PM2.5) with a particle size of less than or equal to 2.5 μm from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 5 minutes.

[0106] Comparative Example 1:

[0107] A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification includes the following steps:

[0108] Step 1: Preparation of dialdehyde cellulose nanofibers: Mix 3g of cellulose powder with 4.5g of sodium periodate, add 30mL of H2SO4 solution with pH=3, ball mill at 500r / min for 3h, then wash with deionized water by centrifugation several times until neutral, finally disperse in 100mL of deionized water, and ultrasonically break it up for 4h using an ultrasonic disruptor (power: 300W; 5s on, 3s off), centrifuge at 3000r / min to collect the upper colloidal liquid, and obtain a dialdehyde cellulose nanofiber suspension;

[0109] Step 2, Preparation of 3D porous nanocellulose aerogel: Measure out a suspension containing 1.5g of dialdehyde cellulose nanofibers and add deionized water to make the total solvent volume 100mL. Then transfer it to a plastic template and pre-freeze it at -40℃ for 6h. After it freezes and solidifies, transfer it to a freeze dryer at -50℃ and dry it for 36h to obtain 3D porous nanocellulose aerogel.

[0110] Step 3: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel prepared in Step 2 was placed in the same sealed container with a glass dish containing 1 mL of aniline and heat-treated at 100℃ for 5 h to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel was placed in a corona polarization device, the polarization voltage was adjusted to 10 kV, the polarization distance to 2 cm, the polarization temperature to 35℃, and the polarization air humidity to 20% RH, and the material was corona polarized for 10 min to obtain 3D porous nanocellulose aerogel electret material.

[0111] Figure 7 The image shows a SEM image of the 3D porous nanocellulose aerogel electret material prepared in Comparative Example 1 of this invention. As can be seen from the image, the electret material has a "nanopaper" sheet structure.

[0112] The surface potential of the 3D porous nanocellulose aerogel electret material prepared in this embodiment was 0.02 kV after 420 min. This was achieved by reducing the surface potential of radioactive aerosols (R-PM2.5) with a particle size of 2.5 μm or less from 999 μg / m³. 3 Reduced to 0ug / m 3 The required purification time is 51 minutes.

[0113] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A method for preparing a 3D porous nanocellulose aerogel electret material for radioactive aerosol purification, characterized in that, Includes the following steps: Step 1: Preparation of dialdehyde cellulose nanofibers: cellulose powder is mixed with sodium periodate, and dialdehyde cellulose nanofibers are obtained by combining a ball mill and an ultrasonic crusher. Step 2, Preparation of ethyl cellulose nanofibers: Ethyl cellulose is dissolved in N,N-dimethylacetamide solvent and electrospinned to obtain ethyl cellulose nanofibers; Step 3: Preparation of 3D porous nanocellulose aerogel: Dialdehyde cellulose nanofibers and ethyl cellulose nanofibers are dispersed in tert-butanol aqueous solution to form a fiber suspension, which is then transferred to a template, pre-frozen, and then freeze-dried to obtain 3D porous nanocellulose aerogel. Step 4: Preparation of 3D porous nanocellulose aerogel electret material: The 3D porous nanocellulose aerogel is heat-treated in aniline vapor to obtain modified 3D porous nanocellulose aerogel; then the modified 3D porous nanocellulose aerogel is corona polarized to obtain 3D porous nanocellulose aerogel electret material. The process of step one is as follows: cellulose powder is mixed with sodium periodate and H2SO4 solution is added. The mixture is ball-milled in a ball mill for 2-4 hours. Then, it is washed by centrifugation with deionized water until it is neutral. Finally, it is dispersed in deionized water and ultrasonically broken up with an ultrasonic disruptor. The upper colloidal liquid is collected by centrifugation at a speed of 2000-3000 r / min to obtain a dialdehyde cellulose nanofiber suspension. In step two, the solid-liquid ratio of ethyl cellulose to N,N-dimethylacetamide is 1g:7~10mL, the electrospinning voltage is 11~15kV, the distance from the needle tip to the receiving plate is 13~17cm, the spinning temperature is 15~35℃, and the spinning air humidity is ≤20~50%RH. In step four, the ratio of 3D porous nanocellulose aerogel to aniline is 0.5~2.5g:0.5~2.5mL, the heat treatment temperature is 90~130℃, and the heat treatment time is 1-7h.

2. The method for preparing 3D porous nanocellulose aerogel electret material for radioactive aerosol purification as described in claim 1, characterized in that, In step one, the solvent for ball milling is H2SO4 solution with pH=3~5, the mass-to-volume ratio of cellulose powder to H2SO4 solution is 1g:10~20mL, the ball milling speed is 300~500r / min, and the ball milling time is 2~4h; the ultrasonic crusher has a crushing power of 200~400W, and the ultrasonic crushing time is 3~6h.

3. The method for preparing 3D porous nanocellulose aerogel electret material for radioactive aerosol purification as described in claim 1, characterized in that, In step one, the mass ratio of cellulose powder to sodium periodate is 1:1~3.

4. The method for preparing 3D porous nanocellulose aerogel electret material for radioactive aerosol purification as described in claim 1, characterized in that, In step three, the mass ratio of dialdehyde cellulose nanofibers to ethyl cellulose nanofibers is 0.1~3:0.1~3, the concentration of tert-butanol aqueous solution is 0~30wt%, the pre-freezing temperature is -20~-190℃, the pre-freezing time is 4~12h, the freeze-drying temperature is -40~-60℃, the freeze-drying time is 24~48h, and the template material is plastic or stainless steel.

5. The method for preparing 3D porous nanocellulose aerogel electret material for radioactive aerosol purification as described in claim 1, characterized in that, In step three, the total mass concentration of the fiber suspension is 0.5-2.5%.

6. The method for preparing 3D porous nanocellulose aerogel electret material for radioactive aerosol purification as described in claim 1, characterized in that, In step four, the corona polarization conditions for the modified 3D porous nanocellulose aerogel are as follows: polarization voltage of 5~15kV, needle-plate distance of 1~4cm, polarization time of 5~30min, polarization temperature of 15~35℃, and polarization air humidity of 15~40%RH.

7. The application of a 3D porous nanocellulose aerogel electret material prepared by the preparation method according to any one of claims 1 to 6 in the purification of radioactive aerosols, characterized in that, The 3D porous nanocellulose aerogel electret material was placed in an environment containing radioactive aerosols to purify the radioactive aerosols.

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