Method for preparation and activation of super-hydrophobic electret fiber material for cleaning PM2.5

Patent metadata

Field	Value
Publication number	US-11014028-B2
Application number	US-201616300168-A
Country	US
Kind code	B2
Filing date	Sep 10, 2016
Priority date	May 17, 2016
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

Disclosed is a method for preparation and activation of a super hydrophobic electret nanofibrous filter material for cleaning PM2.5, comprising the steps as follows: (1) dissolving polymer powders and resin into a corresponding solvent so as to prepare a polymer solution, then stirring on a magnetic stirrer and standing for use; (2) in order to reinforce the electrostatic effect of the fiber, before preparing the polymer solution, adding in organic electret nanoparticles into the solvent, then oscillating with an ultrasonic oscillator; (3) in order to reinforce the super hydrophobic effect of the filter, spraying a low surface energy solution on the prepared nanofiber with a designed nozzle to carry out modification.

First claim

The invention claimed is:

1. A method for preparing and activating a super-hydrophobic electret nanofibrous material for high-efficient cleaning PM2.5 particulate matter, wherein the method comprises:
preparing a nanofibrous material by an electrostatic spinning method, wherein the spinning material comprises polyvinylidene fluoride, polyvinyl chloride, polyacrylonitrile, polycarbonate, polyetherimide, polystyrene, polyurethane, or mixtures thereof; and in order to reinforce the electrostatic effect of the nanofiber layer, adding inorganic electret nanoparticles into the spinning solution, wherein the inorganic electret nanoparticle comprises silicon dioxide, titanium dioxide, barium titanate, silicon nitride, or mixtures thereof; and
wherein solute and solvent in the low surface energy solution respectively comprise:
stearic acid:anhydrous ethanol; hexadecyltrimethoxysilane:methanol; 1H,1H,2H,2H-perfluorohydrocarbyltriethoxysilane:anhydrous ethanol; or 1H,1H,2H,2H-perfluorohydrocarbyltrichlorosilane:anhydrous ethanol;
spraying the prepared nanofiber with a low surface energy solution from a designed nozzle, wherein the low surface energy solution comprises stearic acid solution, hexadecyltrimethoxysilane solution, 1H,1H,2H,2H-perfluorohydrocarbyltriethoxysilane solution, 1H,1H,2H,2H-perfluorohydrocarbyltrichlorosilane solution, or mixtures thereof.

2. A method for preparing and activating a super-hydrophobic electret nanofibrous material for high-efficient cleaning PM2.5 particulate matter, wherein the method comprises: cleaning and regenerating filter material comprising PM2.5 particles by placing the filter material into a cleaning and regeneration apparatus comprising positive plate electrode, negative plate electrode, high-voltage generator, power supply, and nozzle and applying a high voltage having the same charge as the PM2.5 particles and purging the apparatus to remove the PM2.5 particles.

3. The method of claim 1 , wherein the electrostatic spinning method comprises:
(1) preparing a polymer solution by adding 0.5-5 wt. % of one or more types of the inorganic electret nanoparticles into a solvent and ultrasonically oscillating the solution for 1-5 hr, adding 5-25 wt. % of polymer to the solution stirring the solution on a magnetic stirrer for 6-12 hr, and stood for use,
(2) electrostatic spinning: pasting a non-woven fabric on a rotating drum receiver, adjusting the electrostatic spinning parameters to control the morphology of the electret nanofiber, wherein the process conditions for electrostatic spinning are as follows: the electric voltage is 10-30 kV, the receiving distance is 5-25 cm, the injection speed is 1-5 mL/h, the temperature is 0-35° C., and the relative humidity is 0-70%.

4. The method of claim 1 , wherein the method for super-hydrophobization of the electret nanofiber layer comprises:
(1) preparing the low surface energy solution by mixing stearic acid solution, hexadecyltrimethoxysilane solution, 1H,1H,2H,2H-perfluorohydrocarbyltriethoxysilane solution, 1H,1H,2H,2H-perfluorohydrocarbyltrichlorosilane solution, or mixtures thereof as solute with methanol or anhydrous ethanol solvent, wherein the volume fraction of the solute to the solvent in the low surface energy solution is 1:1000,
(2) spraying the low surface energy solution with a designed nozzle to carry out surface modification of the prepared nanofiber, wherein the nozzle is composed of a sampling barrel, a nitrogen bottle, a gas pipe, a gas control knob, a liquid control knob, and an injection needle, and the spraying time is 1-3 s.

5. The method of claim 2 , wherein the method for cleaning and regeneration of the fiber material comprises:
(1) cleaning the fiber material saturated with PM2.5 particles by placing the fiber material in a high-voltage electric field as a barrier medium, applying a high-voltage having the same charge as the PM2.5 particles, and at the same time carrying out purging, thus due to the repulsive interaction with the particle charge, obtaining the cleaning effect, and the particulates being taken away with the purging gas; wherein during the cleaning process, the high-voltage is 5-15 kV, the electrode type is plate; the area is equivalent to the area of the fiber material, the distance between the positive electrode and the negative electrode is 10-50 mm; and the processing time is not less than 5 s,
(2) spraying a low surface energy solution with a designed nozzle to carry out surface modification of the fiber material, wherein the nozzle comprises a sampling barrel, a nitrogen bottle, a gas pipe, a gas control knob, a liquid control knob, and an injection needle; and the spraying time is 1-3 s,
(3) regenerating by placing the sprayed filter material in a high-voltage electric field as a barrier medium again, reversing the positive electrode and the negative electrode in the high-voltage electric field to carry out a high-voltage charged processing, so that the filter material is recharged, wherein during the regeneration process, the high-voltage is 5-15 kV and the processing time is not less than 5 s.

6. The method of claim 1 , wherein solute and solvent in a polymer solution for use in the electrostatic spinning method respectively comprise:
polyvinylidene fluoride:N,N-dimethylformamide and butanone in a mass ratio of 1:1; polyvinyl chloride:N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 1:1; polyacrylonitrile:N,N-dimethylformamide; polycarbonate:dichloromethane; polyetherimide:N,N-dimethylformamide and methyl pyrrolidone in a mass ratio of 1:1; polystyrene:N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1; or polyurethane:butanone.

7. The method of claim 1 , wherein a polymer solution for use in the electrostatic spinning method comprises one or more types of inorganic electret nanoparticles, the inorganic electret nanoparticle comprising silicon dioxide, titanium dioxide, barium titanate, silicon nitride, or mixtures thereof, and the specification of the inorganic electret nanoparticle respectively comprises:
silicon dioxide: 99.5%, 15 nm; titanium dioxide: 99.8%, 40 nm; barium titanate: 99.9%, <100 nm; or silicon nitride: 95%, 85 nm.

8. The method of claim 1 , wherein the filter material has a two-layer structure of non-woven fabric and super-hydrophobic electret nanofiber, the grams per square meter of the non-woven fabric is 100-350 g/m 2 , the thickness is 1-10 mm, and the filtration efficiency of the blank non-woven fabric for small particle having a particle diameter of 0.3 μm is 13.47%.

9. The method of claim 1 , wherein the filter material has a two-layer structure of non-woven fabric and super-hydrophobic electret nanofiber, the nanofiber layer has a nanofiber diameter between 100 nm and 900 nm, a grams per square meter of 0.01-5 g/m 2 , a porosity of 85%, a surface potential of 1000V-4000V, a hydrophobic angle of more than 150°, a filtration efficiency for the particle having a particle diameter range of 0.3-10 μm of up to 99%, and a pressure drop of less than 20 Pa.

Assignees

• Univ South China Tech

Inventors

• Zhang Lizhi
• Bao Aibing
• Cai Rongrong

Classifications

• B01D46/785

  by electrical means, e.g. for the generation of electrostatic forces in order to reject particles · CPC title

• B01D46/70

  by acting counter-currently on the filtering surface, e.g. by flushing on the non-cake side of the filter · CPC title

• B01D46/71

  with pressurised gas, e.g. pulsed air · CPC title

• B29K2033/20

  PAN, i.e. polyacrylonitrile · CPC title

• B01D2239/0435

  Electret · CPC title