CN107486033B - Bacterial cellulose nanofiber composite membrane for air filtration and preparation method thereof - Google Patents
Bacterial cellulose nanofiber composite membrane for air filtration and preparation method thereof Download PDFInfo
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- CN107486033B CN107486033B CN201710649269.6A CN201710649269A CN107486033B CN 107486033 B CN107486033 B CN 107486033B CN 201710649269 A CN201710649269 A CN 201710649269A CN 107486033 B CN107486033 B CN 107486033B
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Abstract
The invention discloses a bacterial cellulose nanofiber composite membrane for air filtration and a preparation method thereof. The preparation method comprises the following steps: mechanically dissociating the bacterial cellulose membrane, dispersing the bacterial cellulose membrane in an insoluble solvent, and adding a dispersing agent to form a stable bacterial cellulose nanofiber suspension; spreading the bacterial cellulose nanofiber suspension on the surface of the porous fiber base material by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane; removing residual solvent in the wet composite fiber membrane to obtain an unmodified composite fiber membrane; and performing surface hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, the surface of which is provided with a completely covered continuous two-dimensional reticular structure. The surface of the composite membrane is a completely covered continuous two-dimensional reticular structure formed by bacterial cellulose nanofibers. The invention can realize effective filtration of solid particles in the air through physical interception under low resistance pressure drop and has stable filtration performance.
Description
Technical Field
The invention relates to a bacterial cellulose nanofiber composite membrane for air filtration and a preparation method thereof, and belongs to the technical field of nanofiber composite membrane materials.
Background
The current serious haze pollution causes great threat to the production, life and body health of people, so that the effective protection of the haze pollution becomes the problem which is urgently needed to be solved at present. The air filtering material becomes a hot spot of research in the field of current air filtering because various hazards caused by haze pollution can be effectively dealt with. Most of the conventional air filter materials are electret fiber materials, and related patents include a preparation method of a melt-blown polypropylene electret filter material (CN101905101A), an electrostatic electret air filter material (CN205055621U) and an electrostatic spinning nanofiber electret filter material and a preparation method thereof (CN104289042A), wherein the air filter performance of the material is improved by endowing the fiber electret with performance, but electret charges are easily attenuated and dissipated by environmental influence, and the filter performance of the material is reduced after electret failure is caused by thick fiber diameter and large pore diameter. Therefore, the development of small-aperture fiber air filtration membranes based on physical interception is the key to solve the above problems. Patent "preparation method of nano spider web/nano fiber composite type protective material" (CN101564914) and literature [ flexible characterization of three-dimensional polyamide-66 nano-fiber/nets for high efficiency fine particulate filtration [ J ]. Journal of Materials Chemistry, 2012, 22 (4): 1445-1452 and [ Ultra-light 3D nano-fibrous composite membrane for the effective filtration of fine particulate matter [ J ]. Journal of Materials Chemistry A, 2015, 3, 23946-23954] disclose and report a method for preparing a small pore size nano-spider web air filter membrane which can effectively intercept solid particulate matter in air by physical sieving, has long-term stable air filtration performance, but because of the limited area of spider web coverage, it is difficult to obtain a structurally continuous two-dimensional network material, so the pore size of the fiber membrane can only be reduced by means of close packing of spider web layers, which causes the reduction of the porosity of the spider web air filter membrane to cause the excessive pressure drop of resistance thereof. Therefore, a method for effectively preparing a small-aperture fiber air filtration membrane with a fully covered continuous two-dimensional network structure and high porosity is needed.
Disclosure of Invention
The invention aims to solve the problems that: provides a bacterial cellulose nanofiber composite membrane for air filtration and a preparation method thereof.
In order to solve the problems, the invention provides a preparation method of a bacterial cellulose nanofiber composite membrane for air filtration, which is characterized by comprising the following specific steps of:
step 1): mechanically dissociating the bacterial cellulose membrane, dispersing the bacterial cellulose membrane in an insoluble solvent, and adding a dispersing agent to form a stable bacterial cellulose nanofiber suspension;
step 2): spreading the bacterial cellulose nanofiber suspension prepared in the step 1) on the surface of a porous fiber base material by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane;
step 3): removing residual solvent in the wet composite fiber membrane prepared in the step 2) to obtain an unmodified composite fiber membrane;
step 4): carrying out surface hydrophobic modification treatment on the unmodified composite fiber membrane prepared in the step 3) to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite fiber membrane is provided with a completely covered continuous two-dimensional reticular structure.
Preferably, the mechanical dissociation in the step 1) is any one or a combination of several of high-speed stirring dissociation, ultrasonic dissociation, high-pressure homogeneous dissociation, high-speed grinding dissociation and freeze grinding dissociation.
Preferably, the insoluble solvent in step 1) is any one or more of water, methanol, ethanol, propanol, isopropanol, tert-butanol, acetone and butanone.
Preferably, the dispersing agent in step 1) is one or more selected from alkylphenol ethoxylates, fatty alcohol-polyoxyethylene ethers, fatty acid-polyoxyethylene esters, fatty acid methyl ester ethoxylates, polyoxyethylene amines, polyoxyethylene amides, sodium stearate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium hexametaphosphate, sodium polysilicate, potassium pyrophosphate, anhydrous sodium carbonate, sodium thiosulfate and sodium borate.
Preferably, the average length of the bacterial cellulose nanofibers in the bacterial cellulose nanofiber suspension is 1-300 μm, the average diameter is 10-100 nm, and the mass percentage of the fibers is 0.0005-1 wt%.
Preferably, the method for synchronous ultrasonic filtration in step 2) specifically comprises: and (3) treating the bacterial cellulose nanofiber suspension by using ultrasonic waves while filtering, wherein the output power of the ultrasonic waves is 100-1500W, the applied pressure during filtering is positive pressure or negative pressure, and the applied pressure range is 0.5-50 kPa.
Preferably, the porous fiber substrate in step 2) is any one or a combination of several of an electrostatic spinning fiber membrane, a non-woven fabric, a cellulose filter paper, a woven fabric and a knitted fabric.
Preferably, the pore diameter of the porous fiber base material is 1-300 μm.
Preferably, the specific method for removing in step 3) is as follows: any one of vacuum drying, forced air drying, supercritical drying, freeze drying, microwave drying and infrared drying.
Preferably, the surface hydrophobic modification treatment in the step 4) is any one of solution impregnation hydrophobic modification treatment, grafting hydrophobic modification treatment, physical vapor deposition hydrophobic modification treatment, chemical vapor deposition hydrophobic modification treatment, low-temperature plasma hydrophobic modification treatment and irradiation hydrophobic modification treatment.
The invention also provides a composite membrane prepared by the preparation method of the bacterial cellulose nanofiber composite membrane for air filtration, which is characterized in that the surface of the composite membrane is a completely covered continuous two-dimensional reticular structure formed by bacterial cellulose nanofibers, the average pore diameter of meshes is 0.1-2 mu m, the porosity of the composite membrane is 70-98%, the filtration efficiency of the composite membrane on particles with the particle diameter of 0.3-10 mu m is more than or equal to 90%, and the resistance pressure drop is 10-120 Pa.
Compared with the prior art, the invention has the beneficial effects that:
unlike electret fiber air filter membranes, the composite membrane prepared by the invention intercepts solid particles in air by utilizing the physical screening effect of fiber meshes, so that the problem of reduced material filtering performance caused by electret charge dissipation can be avoided.
The invention is different from a nano-cobweb air filtering material, the bacterial cellulose nanofiber composite membrane for air filtering is prepared by carrying out synchronous ultrasonic filtering and hydrophobic modification treatment on a mechanically dissociated bacterial cellulose nanofiber suspension for the first time, and the problem that the air resistance pressure drop is large due to low porosity of a fiber membrane caused by the close accumulation of nano-cobweb layers can be effectively solved.
The bacterial cellulose nanofiber composite membrane for air filtration, prepared by the invention, has a continuous two-dimensional network structure with a completely covered surface and high porosity, so that the solid particles in the air can be effectively filtered under low resistance pressure drop through physical interception, and the bacterial cellulose nanofiber composite membrane has stable filtration performance and wide application prospects in the fields of individual protection, environmental management, medicine, health and the like.
Drawings
FIG. 1 is a schematic view of a simultaneous ultrasonic filtration apparatus;
FIG. 2 is an electron micrograph of the bacterial cellulose nanofiber composite membrane for air filtration prepared in example 4; in the figure: a is bacterial cellulose nanofiber; b is a porous fiber receiving substrate.
Detailed Description
In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.
The simultaneous ultrasonic filter apparatus used in examples 1 to 15 is shown in fig. 1, wherein a porous fiber-receiving substrate 3 is placed on a filter apparatus 4, a bacterial cellulose nanofiber suspension 1 is placed on the porous fiber-receiving substrate 3, and an ultrasonic system 2 is placed around the bacterial cellulose nanofiber suspension 1.
Example 1
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 300 mu m and the average diameter of 100nm by adopting a high-speed stirring dissociation method, dispersing the bacterial cellulose nanofibers in water, and adding a dispersing agent alkylphenol ethoxylates to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.05 wt%;
step 2: spreading the bacterial cellulose nanofiber suspension on the surface of cellulose filter paper with the pore diameter of 300 mu m by adopting a synchronous ultrasonic filtration (as shown in figure 1) method to form a wet composite fiber membrane; the ultrasonic output power used in the synchronous ultrasonic filtering process is 1000W, the pressure applied during filtering is positive pressure, and the pressure is 40 kPa;
and step 3: removing residual water in the wet composite fiber membrane by vacuum drying at 80 ℃ for 30min to obtain an unmodified composite fiber membrane;
and 4, step 4: and carrying out solution dipping hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 2 microns, the porosity of the composite membrane is 80%, the filtration efficiency of a TSI8130 filter material tester on particles with the particle size of 10 microns is 100%, and the resistance pressure drop is 10 Pa.
Example 2
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 220 microns and the average diameter of 90nm by adopting an ultrasonic dissociation method, dispersing the bacterial cellulose nanofibers in methanol, and adding a dispersing agent fatty alcohol-polyoxyethylene ether to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.002 wt%
Step 2: spreading the bacterial cellulose nanofiber suspension on the surface of polyethylene terephthalate spun-bonded non-woven fabric with the pore diameter of 150 mu m by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane; the ultrasonic output power used in the synchronous ultrasonic filtering process is 800W, the pressure applied during filtering is negative pressure, and the pressure is 5 kPa;
and step 3: removing residual methanol in the wet composite fiber membrane by adopting forced air drying at 50 ℃ for 20min to obtain an unmodified composite fiber membrane;
and 4, step 4: and (2) carrying out grafting hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 1.5 mu m, the porosity of the composite membrane is 70%, the filtration efficiency of a TSI8130 filter material tester on 5 mu m particles is 100%, and the resistance pressure drop is 30 Pa.
Example 3
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 100 mu m and the average diameter of 50nm by adopting a high-pressure homogeneous dissociation method, dispersing the bacterial cellulose nanofibers in ethanol, and adding a dispersing agent sodium stearate to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.001 wt%;
step 2: spreading the bacterial cellulose nanofiber suspension on the surface of a polypropylene melt-blown non-woven fabric with the pore diameter of 80 mu m by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane; the ultrasonic output power used in the synchronous ultrasonic filtration process is 500W, the pressure applied during filtration is positive pressure, and the pressure is 30 kPa;
and step 3: freezing the wet composite fiber membrane in liquid nitrogen at-196 deg.C for 1min, and freeze-drying to remove residual ethanol to obtain unmodified composite fiber membrane;
and 4, step 4: and carrying out physical vapor deposition hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 1 micrometer, the porosity of the composite membrane is 85%, the filtration efficiency of particles with the particle size of 2 micrometers is 99% by utilizing a TSI8130 filter material tester, and the resistance pressure drop is 50 Pa.
Example 4
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nano-fibers with the average length of 20 mu m and the average diameter of 40nm by adopting a high-speed grinding dissociation method, dispersing the bacterial cellulose nano-fibers into a mixed solvent of water and propanol, and adding a dispersing agent sodium dodecyl benzene sulfonate to form a stable bacterial cellulose nano-fiber suspension; the mass fraction of the bacterial cellulose nano-fibers in the suspension is 0.005 wt%;
step 2: the bacterial cellulose nano-fiber suspension is spread on the surface of a polysulfone electrostatic spinning fiber membrane with the aperture of 6 mu m by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane; the ultrasonic output power used in the synchronous ultrasonic filtering process is 300W, the pressure applied in the filtering process is negative pressure, and the pressure is 10 kPa;
and step 3: removing residual water and propanol in the wet composite fiber membrane by using a supercritical drying method to obtain an unmodified composite fiber membrane;
and 4, step 4: and (2) carrying out chemical vapor deposition hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane (shown in figure 2) for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.8 mu m, the porosity of the composite membrane is 90%, the filtration efficiency of a TSI8130 filter material tester on impurities with the particle size of 0.3 mu m is 90%, and the resistance pressure drop is 60 Pa.
Example 5
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 50 microns and the average diameter of 30nm by adopting a method combining high-speed stirring dissociation and freeze grinding dissociation, dispersing the bacterial cellulose nanofibers in a mixed solvent of water and isopropanol, and adding a dispersing agent sodium hexametaphosphate to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fibers in the suspension is 1 wt%;
step 2: spreading the bacterial cellulose nanofiber suspension on the surface of a silicon dioxide electrostatic spinning fiber membrane with the aperture of 30 mu m by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane; the ultrasonic output power used in the synchronous ultrasonic filtering process is 1500W, the pressure applied during filtering is positive pressure, and the pressure is 50 kPa;
and step 3: removing residual water and isopropanol in the wet composite fiber membrane by adopting a microwave drying method to obtain an unmodified composite fiber membrane;
and 4, step 4: and (2) carrying out low-temperature plasma hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.5 mu m, the porosity of the composite membrane is 80%, the filtration efficiency of a TSI8130 filter material tester on impurities with the particle size of 1 mu m is 99.99%, and the resistance pressure drop is 80 Pa.
Example 6
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 1 mu m and the average diameter of 10nm by adopting a method combining high-speed stirring dissociation, ultrasonic dissociation and high-pressure homogenizing dissociation, dispersing the bacterial cellulose nanofibers in a mixed solvent of water and tert-butyl alcohol, and adding a dispersing agent fatty acid polyoxyethylene ester to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fibers in the suspension is 0.0005 wt%;
step 2: the bacterial cellulose nanofiber suspension is spread on the surface of an electrostatic spinning fiber membrane with the aperture of 1 mu m formed by multi-jet blending of polyacrylonitrile and polyamide 6 by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane; the ultrasonic output power used in the synchronous ultrasonic filtering process is 100W, the pressure applied in the filtering process is negative pressure, and the pressure is 0.5 kPa;
and step 3: removing residual water and tert-butyl alcohol in the wet composite fiber membrane by adopting an infrared drying method to obtain an unmodified composite fiber membrane;
and 4, step 4: and (2) carrying out irradiation hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.1 mu m, the porosity of the composite membrane is 98%, the filtration efficiency of a TSI8130 filter material tester on impurities with the particle size of 0.3 mu m is 99.99%, and the resistance pressure drop is 100 Pa.
Example 7
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 30 mu m and the average diameter of 20nm by adopting a method combining ultrasonic dissociation and high-pressure homogeneous dissociation, dispersing the bacterial cellulose nanofibers in a mixed solvent of water and ethanol, and adding a dispersing agent sodium polysilicate to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.003 wt%;
step 2: the bacterial cellulose nanofiber suspension is paved on the surface of a double-layer fiber membrane by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane, wherein the upper layer of the double-layer fiber membrane is a polyacrylonitrile electrostatic spinning fiber membrane with the pore diameter of 20 mu m, and the lower layer of the double-layer fiber membrane is polypropylene melt-blown non-woven fabric with the pore diameter of 80 mu m; the ultrasonic output power used in the synchronous ultrasonic filtering process is 180W, the pressure applied during filtering is positive pressure, and the pressure is 5 kPa;
and step 3: removing residual water and ethanol in the wet composite fiber membrane by vacuum drying at 60 ℃ for 15min to obtain an unmodified composite fiber membrane;
and 4, step 4: and carrying out solution dipping hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.2 mu m, the porosity of the composite membrane is 95%, the filtration efficiency of a TSI8130 filter material tester on particles with the particle size of 0.3 mu m is 99.9%, and the resistance pressure drop is 95 Pa.
Example 8
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 20 microns and the average diameter of 30nm by adopting a high-speed stirring dissociation method, dispersing the bacterial cellulose nanofibers in a mixed solvent of water and methanol, and adding potassium pyrophosphate serving as a dispersing agent to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.05 wt%;
step 2: the bacterial cellulose nanofiber suspension is spread on the surface of a double-layer fiber membrane by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane, wherein the upper layer of the double-layer fiber membrane is a polycaprolactone electrostatic spinning fiber membrane with the aperture of 10 mu m, and the lower layer of the double-layer fiber membrane is a fibrilia woven fabric with the aperture of 300 mu m; the ultrasonic output power used in the synchronous ultrasonic filtering process is 800W, the pressure applied during filtering is negative pressure, and the pressure is 20 kPa;
and step 3: freezing the wet composite fiber membrane in liquid nitrogen at-196 deg.C for 2min, and freeze-drying to remove residual water and methanol to obtain unmodified composite fiber membrane;
and 4, step 4: and (2) carrying out grafting hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.5 mu m, the porosity of the composite membrane is 85%, the filtration efficiency of a TSI8130 filter material tester on particles with the particle size of 0.5 mu m is 99%, and the resistance pressure drop is 75 Pa.
Example 9
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 60 mu m and the average diameter of 50nm by adopting a method combining freeze grinding dissociation and ultrasonic dissociation, dispersing the bacterial cellulose nanofibers into a mixed solvent of water and acetone, and adding a dispersing agent polyoxyethylene amine and polyoxyethylene amide to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.2 wt%;
step 2: the bacterial cellulose nanofiber suspension is paved on the surface of a double-layer fiber membrane by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane, the upper layer of the double-layer fiber membrane is electrostatic spinning nanofiber with the aperture of 50 mu m formed by blending and spinning polylactic acid and polycaprolactone, and the lower layer of the double-layer fiber membrane is wool fiber knitted fabric with the aperture of 300 mu m; the ultrasonic output power used in the synchronous ultrasonic filtration process is 1000W, the pressure applied during filtration is positive pressure, and the pressure is 30 kPa;
and step 3: removing residual water and acetone in the wet composite fiber membrane by vacuum drying at 40 ℃ for 60min to obtain an unmodified composite fiber membrane;
and 4, step 4: and (2) carrying out physical vapor deposition hydrophobic modification treatment on the composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.2 mu m, the porosity of the composite membrane is 90%, the filtration efficiency of a TSI8130 filter material tester on particles with the particle size of 0.3 mu m is 99.9%, and the resistance pressure drop is 105 Pa.
Example 10
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nano-fibers with the average length of 80 mu m and the average diameter of 80nm by adopting a high-speed stirring dissociation method, dispersing the bacterial cellulose nano-fibers into water, and adding a dispersing agent fatty acid methyl ester ethoxylate to form a stable bacterial cellulose nano-fiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.5 wt%;
step 2: the bacterial cellulose nanofiber suspension is paved on the surface of a double-layer fiber membrane by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane, wherein the upper layer of the double-layer fiber membrane is a cellulose acetate electrostatic spinning fiber membrane with the aperture of 50 mu m, and the lower layer of the double-layer fiber membrane is cellulose filter paper with the aperture of 100 mu m; the ultrasonic output power used in the synchronous ultrasonic filtration process is 1000W, the pressure applied during filtration is positive pressure, and the pressure is 30 kPa;
and step 3: removing residual water in the wet composite fiber membrane by adopting air blast drying at 80 ℃ for 20min to obtain an unmodified composite fiber membrane;
and 4, step 4: and carrying out chemical vapor deposition hydrophobic modification treatment on the composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.5 mu m, the porosity of the composite membrane is 90%, the filtration efficiency of a TSI8130 filter material tester on particles with the particle size of 1 mu m is 99.99%, and the resistance pressure drop is 70 Pa.
Example 11
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 10 mu m and the average diameter of 50nm by adopting a method combining high-speed stirring dissociation and freeze grinding dissociation, dispersing the bacterial cellulose nanofibers in water, and adding a dispersing agent anhydrous sodium carbonate to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.002 wt%;
step 2: the bacterial cellulose nanofiber suspension is paved on the surface of a double-layer fiber membrane by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane, wherein the upper layer of the double-layer fiber membrane is a polyisophthaloyl metaphenylene diamine electrostatic spinning fiber membrane with the aperture of 8 mu m, and the lower layer of the double-layer fiber membrane is a polyacrylonitrile electrostatic spinning fiber membrane with the aperture of 20 mu m; the ultrasonic output power used in the synchronous ultrasonic filtering process is 100W, the pressure applied in the filtering process is negative pressure, and the pressure is 10 kPa;
and step 3: removing residual water in the wet composite fiber membrane by adopting vacuum drying at 100 ℃ for 10min to obtain an unmodified composite fiber membrane;
and 4, step 4: and (2) carrying out low-temperature plasma hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.1 mu m, the porosity of the composite membrane is 90%, the filtration efficiency of a TSI8130 filter material tester on 0.3 mu m particles is 99.99%, and the resistance pressure drop is 120 Pa.
Example 12
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 5 microns and the average diameter of 20nm by adopting a method combining high-speed stirring dissociation and ultrasonic dissociation, dispersing the bacterial cellulose nanofibers in water, and adding a dispersing agent sodium hexametaphosphate to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.005 wt%;
step 2: the bacterial cellulose nanofiber suspension is laid on the surfaces of three layers of fiber membranes by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane, wherein the upper layer of the three layers of fiber membranes is a polyacrylonitrile electrostatic spinning fiber membrane with the pore diameter of 3 mu m, the middle layer is polysulfone electrostatic spinning fiber with the pore diameter of 10 mu m, and the lower layer is polypropylene melt-blown non-woven fabric with the pore diameter of 50 mu m; the ultrasonic output power used in the synchronous ultrasonic filtering process is 500W, the pressure applied in the filtering process is negative pressure, and the pressure is 40 kPa;
and step 3: removing residual water in the wet composite fiber membrane by adopting forced air drying at 60 ℃ for 40min to obtain an unmodified composite fiber membrane;
and 4, step 4: and (2) carrying out irradiation hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.2 mu m, the porosity of the composite membrane is 85%, the filtration efficiency of a TSI8130 filter material tester on particles with the particle size of 0.5 mu m is 100%, and the resistance pressure drop is 110 Pa.
Example 13
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 10 mu m and the average diameter of 20nm by adopting a method combining high-pressure homogeneous dissociation and ultrasonic dissociation, dispersing the bacterial cellulose nanofibers into a mixed solvent of water and butanone, and adding a dispersing agent polyoxyethylene amide to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.05 wt%;
step 2: the bacterial cellulose nanofiber suspension is laid on the surfaces of three layers of fiber membranes by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane, wherein the upper layer of the three layers of fiber membranes is a polyamide 6 electrostatic spinning fiber membrane with the aperture of 5 mu m, the middle layer is polypropylene non-woven fabric with the aperture of 80 mu m, and the lower layer is a cotton fiber knitted fabric with the aperture of 300 mu m; the ultrasonic output power used in the synchronous ultrasonic filtration process is 1000W, the pressure applied during filtration is positive pressure, and the pressure is 30 kPa;
and step 3: removing residual water and butanone in the wet composite fiber membrane by adopting forced air drying at 60 ℃ for 60min to obtain an unmodified composite fiber membrane;
and 4, step 4: and carrying out solution dipping hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.3 mu m, the porosity of the composite membrane is 85%, the filtration efficiency of a TSI8130 filter material tester on particles with the particle size of 0.3 mu m is 99.9%, and the resistance pressure drop is 105 Pa.
Example 14
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 50 microns and the average diameter of 30nm by adopting an ultrasonic dissociation method, dispersing the bacterial cellulose nanofibers in water, and adding a dispersing agent sodium hexametaphosphate to form a stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.001 wt%;
step 2: the bacterial cellulose nanofiber suspension is laid on the surfaces of three layers of fiber membranes by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane, wherein the upper layer of the three layers of fiber membranes is a polyvinylidene fluoride electrospun fiber membrane with the aperture of 30 mu m, the middle layer is polypropylene melt-blown non-woven fabric with the aperture of 80 mu m, and the lower layer is polyacrylonitrile woven fabric with the aperture of 200 mu m; the ultrasonic output power used in the synchronous ultrasonic filtering process is 500W, the pressure applied in the filtering process is negative pressure, and the pressure is 20 kPa;
and step 3: removing residual water in the wet composite fiber membrane by adopting a microwave drying method to obtain an unmodified composite fiber membrane;
and 4, step 4: and (2) carrying out grafting hydrophobic modification treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.5 mu m, the porosity of the composite membrane is 90%, the filtration efficiency of a TSI8130 filter material tester on particles with the particle size of 0.3 mu m is 96%, and the resistance pressure drop is 70 Pa.
Example 15
A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration comprises the following steps:
step 1: mechanically dissociating the bacterial cellulose membrane into bacterial cellulose nanofibers with the average length of 80 mu m and the average diameter of 80nm by adopting a high-speed stirring dissociation method, dispersing the bacterial cellulose nanofibers in water, and adding dispersing agents of sodium stearate and sodium dodecyl sulfate to form stable bacterial cellulose nanofiber suspension; the mass percentage of the bacterial cellulose nano-fiber in the suspension is 0.1 wt%;
step 2: the bacterial cellulose nanofiber suspension is laid on the surfaces of three layers of fiber membranes by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane, wherein the upper layer of the three layers of fiber membranes is polypropylene melt-blown non-woven fabric with the aperture of 50 mu m, the middle layer is wool knitted fabric with the aperture of 100 mu m, and the lower layer is cotton woven fabric with the aperture of 300 mu m; the ultrasonic output power used in the synchronous ultrasonic filtration process is 1000W, the pressure applied during filtration is positive pressure, and the pressure is 30 kPa;
and step 3: removing residual water in the wet composite fiber membrane by adopting vacuum drying at 50 ℃ for 60min to obtain an unmodified composite fiber membrane;
and 4, step 4: and carrying out physical vapor deposition treatment on the unmodified composite fiber membrane to obtain the bacterial cellulose nanofiber composite membrane for air filtration, wherein the surface of the composite membrane is provided with a completely covered continuous two-dimensional reticular structure, the average pore diameter of meshes of the composite membrane is 0.2 mu m, the porosity of the composite membrane is 80%, the filtration efficiency of a TSI8130 filter material tester on particles with the particle size of 0.5 mu m is 100%, and the resistance pressure drop is 115 Pa.
Claims (7)
1. A preparation method of a bacterial cellulose nanofiber composite membrane for air filtration is characterized by comprising the following specific steps:
step 1): mechanically dissociating the bacterial cellulose membrane, dispersing the bacterial cellulose membrane in an insoluble solvent, and adding a dispersing agent to form a stable bacterial cellulose nanofiber suspension;
step 2): spreading the bacterial cellulose nanofiber suspension prepared in the step 1) on the surface of a porous fiber base material by adopting a synchronous ultrasonic filtration method to form a wet composite fiber membrane;
step 3): removing residual solvent in the wet composite fiber membrane prepared in the step 2) to obtain an unmodified composite fiber membrane;
step 4): carrying out surface hydrophobic modification treatment on the unmodified composite fiber membrane prepared in the step 3) to obtain a bacterial cellulose nanofiber composite membrane for air filtration, the surface of which is provided with a completely covered continuous two-dimensional reticular structure;
in the step 1), the insoluble solvent is any one or more of water, methanol, ethanol, propanol, isopropanol, tert-butanol, acetone and butanone;
the dispersing agent in the step 1) is one or more of alkylphenol ethoxylates, fatty alcohol-polyoxyethylene ether, fatty acid-polyoxyethylene ester, fatty acid methyl ester ethoxylate, polyoxyethylene amine, polyoxyethylene amide, sodium stearate, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium hexametaphosphate, sodium polysilicate, potassium pyrophosphate, anhydrous sodium carbonate, sodium thiosulfate and sodium borate;
the average length of the bacterial cellulose nanofibers in the bacterial cellulose nanofiber suspension is 1-300 mu m, the average diameter is 10-100 nm, and the mass percentage of the fibers is 0.0005-1 wt%;
the pore diameter of the porous fiber base material is 1-300 mu m.
2. The method for preparing the composite membrane of bacterial cellulose nanofibers for air filtration according to claim 1, wherein the mechanical dissociation in step 1) is any one or a combination of high-speed stirring dissociation, ultrasonic dissociation, high-pressure homogeneous dissociation, high-speed grinding dissociation and freeze grinding dissociation.
3. The preparation method of the bacterial cellulose nanofiber composite membrane for air filtration according to claim 1, wherein the synchronous ultrasonic filtration method in the step 2) is specifically as follows: and (3) treating the bacterial cellulose nanofiber suspension by using ultrasonic waves while filtering, wherein the output power of the ultrasonic waves is 100-1500W, the applied pressure during filtering is positive pressure or negative pressure, and the applied pressure range is 0.5-50 kPa.
4. The method for preparing the bacterial cellulose nanofiber composite membrane for air filtration according to claim 1, wherein the porous fiber base material in the step 2) is any one or a combination of several of an electrostatic spinning fiber membrane, a non-woven fabric, a cellulose filter paper, a woven fabric and a knitted fabric.
5. The method for preparing the bacterial cellulose nanofiber composite membrane for air filtration according to claim 1, wherein the specific method for removing in the step 3) is as follows: any one of vacuum drying, forced air drying, supercritical drying, freeze drying, microwave drying and infrared drying.
6. The method for preparing the bacterial cellulose nanofiber composite membrane for air filtration according to claim 1, wherein the surface hydrophobic modification treatment in the step 4) is any one of solution dipping hydrophobic modification treatment, grafting hydrophobic modification treatment, physical vapor deposition hydrophobic modification treatment, chemical vapor deposition hydrophobic modification treatment, low-temperature plasma hydrophobic modification treatment and irradiation hydrophobic modification treatment.
7. The composite membrane prepared by the preparation method of the bacterial cellulose nanofiber composite membrane for air filtration according to any one of claims 1 to 6, wherein the surface of the composite membrane is a completely covered continuous two-dimensional network structure formed by the bacterial cellulose nanofibers, the average pore diameter of meshes is 0.1-2 μm, the porosity of the composite membrane is 70-98%, the filtration efficiency of the composite membrane on particles with the particle diameter of 0.3-10 μm is not less than 90%, and the pressure drop resistance is 10-120 Pa.
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