CN116078184A - Nanocellulose-based filter membrane and preparation method and application thereof - Google Patents
Nanocellulose-based filter membrane and preparation method and application thereof Download PDFInfo
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- 239000012528 membrane Substances 0.000 title claims abstract description 140
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- 239000000463 material Substances 0.000 claims abstract description 27
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- 238000010306 acid treatment Methods 0.000 claims description 71
- 239000003513 alkali Substances 0.000 claims description 62
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- UKLNMMHNWFDKNT-UHFFFAOYSA-M sodium chlorite Chemical compound [Na+].[O-]Cl=O UKLNMMHNWFDKNT-UHFFFAOYSA-M 0.000 claims description 36
- 229960002218 sodium chlorite Drugs 0.000 claims description 36
- 239000012362 glacial acetic acid Substances 0.000 claims description 34
- 238000000034 method Methods 0.000 claims description 30
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- 125000002791 glucosyl group Chemical group C1([C@H](O)[C@@H](O)[C@H](O)[C@H](O1)CO)* 0.000 description 1
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Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/08—Polysaccharides
- B01D71/10—Cellulose; Modified cellulose
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
- B01D17/02—Separation of non-miscible liquids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/10—Supported membranes; Membrane supports
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/36—Hydrophilic membranes
Abstract
The invention belongs to the technical field of membrane separation, and particularly relates to a nanocellulose-based filter membrane, and a preparation method and application thereof. The preparation method provided by the invention comprises the following steps: removing lignin and hemicellulose from the biomass material powder to obtain cellulose powder; dispersing the cellulose powder in water to obtain a cellulose suspension; ultrasonically crushing the cellulose suspension to obtain a nanocellulose solution; forming a film from the nanocellulose solution to obtain a liquid film; the mass percentage of the nano cellulose solution is more than or equal to 1 percent; and drying the liquid membrane to obtain the hydrophilic oleophobic nanocellulose-based filter membrane. The preparation method provided by the invention has the advantages of wide sources of raw materials and low cost; the obtained hydrophilic oleophobic filter membrane can be recycled after being used, is formed into a membrane again, can be completely degraded by soil, is environment-friendly, can realize efficient separation of an oil-water mixture, and can be reused.
Description
Technical Field
The invention belongs to the technical field of membrane separation, and particularly relates to a nanocellulose-based filter membrane, and a preparation method and application thereof.
Background
Oil-water mixtures are produced in industrial production and daily life. If not timely separated, environmental pollution and resource waste can be caused. The conventional oil-water separation method comprises an additional demulsifier method (suitable for emulsion), a centrifugal method (suitable for emulsion and oil-water mixture) and a membrane separation method. The former two are relatively conventional mature methods, the latter being novel separation methods that have emerged with membrane science in recent years. The method of adding demulsifiers needs a large amount of demulsifiers, and has high cost; the energy consumption of the centrifugal method is high; thus, the method is applicable to a variety of applications. Membrane separation is becoming more and more interesting and studied.
Membrane separation processes are classified into different types according to the nature of the membrane. The membrane layer has strong affinity with the continuous phase of the mixture to be separated, and has repulsive interaction with the dispersed phase, so that the purpose of separation is achieved through filtration. The current common oleophylic and hydrophobic membrane is a polyvinylidene fluoride membrane (PVDF membrane), but the production cost of the PVDF membrane is still high, and the PVDF membrane can only be abandoned and cannot be recycled after the membrane layer is blocked and polluted, so that the environmental protection pressure is caused, and the PVDF membrane is not feasible in the aspects of economy and environmental protection.
Disclosure of Invention
The invention aims to provide a nano cellulose-based filter membrane, a preparation method and application thereof, and the nano cellulose-based filter membrane provided by the invention has low preparation cost and can be recycled for film formation again after use; and the gravity can be utilized to realize rapid continuous circulation treatment of large-batch oil-water mixtures, so that the treatment efficiency is high and the treatment effect is good.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a hydrophilic oleophobic nanocellulose-based filter membrane, which comprises the following steps:
removing lignin and hemicellulose from the biomass material powder to obtain cellulose powder;
dispersing the cellulose powder in water to obtain a cellulose suspension;
ultrasonically crushing the cellulose suspension to obtain a nanocellulose solution;
forming a film from the nanocellulose solution to obtain a liquid film; the mass percentage of the nano cellulose solution is more than or equal to 1 percent;
and drying the liquid membrane to obtain the hydrophilic oleophobic nanocellulose-based filter membrane.
Preferably, the drying temperature is less than or equal to 24 ℃, and the drying heat preservation time is more than or equal to 120 hours.
Preferably, the drying comprises the steps of:
performing first drying on the liquid film to obtain a first dried product; the temperature of the first drying is-30 to-50 ℃, and the heat preservation time of the first drying is 8-10 h;
performing second drying on the first dried product to obtain a second dried product; the temperature of the second drying is-8 to-12 ℃, the vacuum degree of the second drying is 1-30 Pa, and the heat preservation and pressure maintaining time of the second drying is 6-8 h;
Thirdly, drying the second dried product to obtain a third dried product; the temperature of the third drying is 0-5 ℃, the vacuum degree of the third drying is 1-30 Pa, and the heat preservation and pressure maintaining time of the third drying is 10-12 h;
fourth drying is carried out on the third dried product to obtain a fourth dried product; the temperature of the fourth drying is 8-12 ℃, the vacuum degree of the fourth drying is 1-30 Pa, and the heat preservation and pressure maintaining time of the fourth drying is 48 hours;
fifth drying the fourth dried product; the temperature of the fifth drying is 16-24 ℃, the vacuum degree of the fifth drying is 1-30 Pa, and the heat preservation and pressure maintaining time of the fifth drying is 48h.
Preferably, the power of the ultrasonic crushing is 600-900W, and the time of the ultrasonic crushing is 25-45 min; the temperature of the ultrasonic crushing is 2-6 ℃.
Preferably, the mass percentage of the cellulose suspension is 0.5-2%.
Preferably, the removing lignin and hemicellulose comprises the steps of:
mixing the biomass material powder, water, sodium chlorite and glacial acetic acid for first acid treatment to obtain first acid treatment powder;
mixing the first acid treatment powder, water and inorganic strong base to perform first alkali treatment to obtain first alkali treatment powder;
Mixing the first alkali treatment powder, water, sodium chlorite and glacial acetic acid to perform second acid treatment to obtain second acid treatment powder;
and mixing the second acid treatment powder, water and inorganic strong base for second alkali treatment to obtain the cellulose powder.
Preferably, during the first acid treatment, the mass ratio of the biomass material powder to the sodium chlorite to the glacial acetic acid is (10-40): 9-20): 3;
when the first alkali treatment is carried out, the mass ratio of the biomass material powder to the inorganic strong alkali is 3 (2.5-5);
the temperature of the first acid treatment and the second acid treatment are independently 50-80 ℃, and the heat preservation time of the first acid treatment and the second acid treatment is independently 5-8 h;
the temperature of the first alkali treatment and the second alkali treatment are independently 70-98 ℃, and the heat preservation time of the first alkali treatment and the second alkali treatment is independently 1-5 h.
The invention provides the hydrophilic oleophobic nanocellulose-based filter membrane prepared by the preparation method, which is a reticular structure membrane formed by intertwining nanocellulose.
The invention provides a composite nano cellulose-based filtering membrane, which comprises a first supporting membrane, a nano cellulose membrane and a second supporting membrane which are sequentially laminated; the nano-cellulose membrane is the hydrophilic oleophobic nano-cellulose-based filter membrane according to the technical scheme.
The invention provides the application of the hydrophilic oleophobic nanocellulose-based filter membrane in the technical scheme or the composite nanocellulose-based filter membrane in the oil-water mixture separation.
The invention provides a preparation method of a hydrophilic oleophobic nanocellulose-based filter membrane, which comprises the following steps: removing lignin and hemicellulose from the biomass material powder to obtain cellulose powder; dispersing the cellulose powder in water to obtain a cellulose suspension; ultrasonically crushing the cellulose suspension to obtain a nanocellulose solution; forming a film from the nanocellulose solution to obtain a liquid film; the mass percentage of the nano cellulose solution is more than or equal to 1 percent; and drying the liquid membrane to obtain the hydrophilic oleophobic nanocellulose-based filter membrane. The preparation method provided by the invention uses biomass materials as raw materials, and has wide sources and low cost; preparing nano cellulose by using biomass materials, and drying to obtain a hydrophilic oleophobic filter membrane made of nano cellulose; can be recycled after being used, forms a film again, can be completely degraded by soil, and is environment-friendly; meanwhile, the mass percentage of the nano cellulose solution is more than or equal to 1% during film formation, so that the oil-water separation film with large specific surface, high porosity and excellent mechanical property can be prepared, the oil-water mixture can be separated efficiently, and the oil-water separation film can be reused.
Further, in the invention, the drying temperature is less than or equal to 24 ℃, and the drying heat preservation time is more than or equal to 120 hours. According to the invention, the temperature and the heat preservation time of drying are preferably controlled, so that the nano cellulose-based filter membrane with uniform texture and no moisture residue can be obtained, the oil-water separation speed of the nano cellulose-based filter membrane is improved, and the filtering efficiency is improved.
Drawings
Fig. 1 is a schematic structural diagram of a separation device used when the hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1 of the present invention is used for separating an oil-water mixture.
In fig. 1: 1-a separation box; 2-nanocellulose-based filter membrane; 3-a first recovery tank; 4-a filter plate; 5-import; 6-outlet; 7-filtering holes; 8-slow flow plates; 9-a second recovery tank; 10-water outlet; 11-emptying port; 12-connecting pipes;
FIG. 2 is a physical diagram of a hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1 of the present invention;
FIG. 3 is an N-type hydrophilic oleophobic nanocellulose-based Filter membrane prepared in example 1 of the present invention 2 An adsorption graph;
FIG. 4 is a BET curve of the hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1 of the present invention.
Detailed Description
The invention provides a preparation method of a hydrophilic oleophobic nanocellulose-based filter membrane, which comprises the following steps:
Removing lignin and hemicellulose from the biomass material powder to obtain cellulose powder;
dispersing the cellulose powder in water to obtain a cellulose suspension;
ultrasonically crushing the cellulose suspension to obtain a nanocellulose solution;
forming a film from the nanocellulose solution to obtain a liquid film; the mass percentage of the nano cellulose solution is more than or equal to 1 percent;
and drying the liquid membrane to obtain the hydrophilic oleophobic nanocellulose-based filter membrane.
In the present invention, all preparation materials/components are commercially available products well known to those skilled in the art unless specified otherwise.
The biomass material powder is subjected to lignin and hemicellulose removal, so that cellulose powder is obtained.
In the invention, the biomass material powder comprises one or more of wood powder, bamboo powder and plant straw powder; the plant straw comprises one or more of cotton straw, corn straw and straw.
In the present invention, the particle diameter of the biomass material powder is preferably not more than 0.425mm, more preferably not more than 0.178mm.
In the present invention, the removal of lignin and hemicellulose preferably comprises the steps of:
Mixing the biomass material powder, water, sodium chlorite and glacial acetic acid for first acid treatment to obtain first acid treatment powder;
mixing the first acid treatment powder, water and inorganic strong base to perform first alkali treatment to obtain first alkali treatment powder;
mixing the first alkali treatment powder, water, sodium chlorite and glacial acetic acid to perform second acid treatment to obtain second acid treatment powder;
and mixing the second acid treatment powder, water and inorganic strong base for second alkali treatment to obtain the cellulose powder.
The biomass material powder, water, sodium chlorite and glacial acetic acid are mixed for the first acid treatment to obtain first acid treatment powder. In the present invention, the mass ratio of the biomass material powder, sodium chlorite and glacial acetic acid in the first acid treatment is preferably (10-40): 9-20): 3, more preferably (15-35): 12-17): 3, and most preferably 30:15:3. The invention has no special requirement on the water consumption, and ensures that the first acid treatment is carried out smoothly. In the present invention, the temperature of the first acid treatment is preferably 50 to 80 ℃, more preferably 55 to 75 ℃; the incubation time for the first acid treatment is preferably 5 to 8 hours, more preferably 5.5 to 7.5 hours. In the present invention, the pH value at the time of the first acid treatment is preferably 1 to 1.5, and in the present invention, the first acid treatment is preferably performed under water bath conditions. In the present invention, the glacial acetic acid and sodium chlorite are preferably supplemented every 1 to 2 hours during the first acid treatment to ensure that the pH of the first acid treatment is preferably 1 to 1.5. In the present invention, the mass ratio of the sodium chlorite to the acetic acid is preferably (9 to 20): 3, more preferably (12 to 17): 3, and most preferably 15:3, each time the glacial acetic acid and the sodium chlorite are supplemented. In the invention, chlorine generated by glacial acetic acid and sodium chlorite reacts with lignin components of the biomass material to generate hypochlorous acid, and lignin is dissolved in an acidic environment and is dissolved in water to be discharged with waste liquid.
In the present invention, the first acid treatment is performed to obtain a first acid treatment solution, and the present invention preferably performs a post-treatment on the first acid treatment to obtain the first acid treatment product. In the present invention, the post-treatment preferably includes the steps of: carrying out solid-liquid separation on the first acid treatment liquid to obtain a solid product; and washing the solid product to be neutral to obtain the first acid treatment powder.
After the first acid treatment powder is obtained, the first acid treatment powder, water and inorganic strong base are mixed for first alkali treatment to obtain the first alkali treatment powder. In the present invention, in the first alkali treatment, the inorganic strong base is preferably an alkali metal hydroxide, and the alkali metal hydroxide is particularly preferably potassium hydroxide. In the present invention, the mass ratio of the biomass material powder to the inorganic strong base is preferably 3 (2.5 to 5), more preferably 3 (3 to 4.5), and most preferably 3:4. In the present invention, the temperature of the first alkali treatment is preferably 70 to 98 ℃, more preferably 75 to 95 ℃; the heat preservation time of the first alkali treatment is preferably 1 to 5 hours, more preferably 2 to 4 hours; the first alkaline treatment is preferably carried out under water bath conditions.
In the present invention, the first alkali treatment is performed to obtain a first alkali treatment solution, and the present invention preferably performs a post-treatment on the first alkali treatment to obtain the first alkali treatment product. In the present invention, the post-treatment preferably includes the steps of: carrying out solid-liquid separation on the first alkali treatment liquid to obtain a solid product; and washing the solid product to be neutral to obtain the first alkali treatment powder.
After the first alkali treatment powder is obtained, the first alkali treatment powder, water, sodium chlorite and glacial acetic acid are mixed for second acid treatment to obtain the second acid treatment powder. In the present invention, the mass ratio of the biomass material powder, sodium chlorite and glacial acetic acid is preferably (10-40): 9-20): 3, more preferably (15-35): 12-17): 3, and most preferably 30:15:3, during the second acid treatment. The invention has no special requirement on the dosage of the water, and ensures that the second acid treatment is smoothly carried out. In the present invention, the temperature of the second acid treatment is preferably 50 to 80 ℃, more preferably 55 to 75 ℃; the holding time of the second acid treatment is preferably 5 to 8 hours, more preferably 5.5 to 7.5 hours. In the present invention, the pH value at the time of the second acid treatment is preferably 1 to 1.5, and in the present invention, the second acid treatment is preferably performed under water bath conditions. In the present invention, in the process of the second acid treatment, glacial acetic acid and sodium chlorite are preferably supplemented every 1 to 2 hours to ensure that the pH value of the second acid treatment is preferably 1 to 1.5. In the present invention, the mass ratio of the sodium chlorite to the acetic acid is preferably (9 to 20): 3, more preferably (12 to 17): 3, and most preferably 15:3, each time the glacial acetic acid and the sodium chlorite are supplemented. In the invention, chlorine generated by glacial acetic acid and sodium chlorite reacts with lignin components of the biomass material to generate hypochlorous acid, and lignin is dissolved in an acidic environment and is dissolved in water to be discharged with waste liquid.
In the present invention, the second acid treatment is performed to obtain a second acid treatment solution, and the present invention preferably performs a post-treatment on the second acid treatment to obtain the second acid treatment product. In the present invention, the post-treatment preferably includes the steps of: carrying out solid-liquid separation on the second acid treatment liquid to obtain a solid product; and washing the solid product to be neutral to obtain the second acid treatment powder.
After the second acid treatment powder is obtained, the second acid treatment powder, water and inorganic strong base are mixed for second alkali treatment, so that the cellulose powder is obtained. In the present invention, in the second alkali treatment, the inorganic strong base is preferably an alkali metal hydroxide, and the alkali metal hydroxide is particularly preferably potassium hydroxide. In the present invention, the mass ratio of the biomass material powder to the inorganic strong base in the second alkali treatment is preferably 3 (2.5 to 5), more preferably 3 (3 to 4.5), and most preferably 3:4. In the present invention, the temperature of the second alkali treatment is preferably 70 to 98 ℃, more preferably 75 to 95 ℃; the heat preservation time of the second alkali treatment is preferably 1 to 5 hours, more preferably 2 to 4 hours; the second alkaline treatment is preferably carried out under water bath conditions.
In the present invention, the second alkali treatment is performed to obtain a second alkali treatment solution, and the present invention preferably performs a post-treatment on the second alkali treatment to obtain the cellulose powder. In the present invention, the post-treatment preferably includes the steps of: carrying out solid-liquid separation on the second alkali treatment liquid to obtain a solid product; and washing the solid product to be neutral to obtain the cellulose powder.
After the cellulose powder is obtained, the cellulose powder is dispersed in water to obtain cellulose suspension. In the present invention, the mass percentage of the cellulose suspension is preferably 0.5 to 2%, more preferably 1 to 1.5%.
After the cellulose suspension is obtained, the cellulose suspension is crushed by ultrasonic waves to obtain a nano cellulose solution. In the present invention, the power of the ultrasonic crushing is preferably 600 to 900W, more preferably 650 to 850W; the time of ultrasonic crushing is preferably 25-45 min, more preferably 30-35 min; the temperature of the ultrasonic disruption is preferably 2 to 6 ℃, more preferably 2.5 to 5 ℃. In the present invention, the ultrasonication is preferably performed in an ultrasonic cytoclasis apparatus; the ultrasonic disruption is preferably performed under ice water bath conditions. In the present invention, the volume of the cellulose suspension to be subjected to the ultrasonic disruption treatment is preferably 500 to 1000mL.
In the present invention, the aspect ratio of the nanocellulose in the nanocellulose solution is preferably 90 to 120.
After the nano cellulose solution is obtained, the nano cellulose solution is formed into a film to obtain a liquid film; the mass percentage of the nano cellulose solution is more than or equal to 1%, and is preferably 1-3%. In the present invention, the film-forming is preferably performed using a molded abrasive, and in the present invention, the molded abrasive is preferably a square plate, and the volume of the nanocellulose solution poured into the square plate is preferably 1000 to 2000mL each time when the square plate has a size of preferably 35cm×50cm×1.5 cm.
After the liquid membrane is obtained, the hydrophilic oleophobic nanocellulose-based filter membrane is obtained by drying the liquid membrane.
In the invention, the drying temperature is preferably equal to or less than 24 ℃, more preferably equal to or less than 22 ℃, and the drying heat preservation time is preferably equal to or more than 120 hours, more preferably 122-126 hours.
The liquid film is preferably subjected to pre-freezing treatment before the drying, and in the method, the temperature of the pre-freezing treatment is preferably 20-30 ℃ below zero, and preferably 22-25 ℃ below zero; the pre-freezing treatment time is preferably 8 to 41 hours, more preferably 9 to 10 hours.
In the present invention, the drying preferably includes the steps of:
performing first drying on the liquid film to obtain a first dried product; the temperature of the first drying is preferably-30 to-50 ℃, more preferably-35 to-45 ℃, and the heat preservation time of the first drying is preferably 8 to 10 hours, more preferably 8.5 to 10 hours;
performing second drying on the first dried product to obtain a second dried product; the temperature of the second drying is preferably-8 to-12 ℃, more preferably-8.5 to-11 ℃, and the vacuum degree of the second drying is preferably 1 to 30Pa, more preferably 1Pa; the heat preservation and pressure maintaining time of the second drying is preferably 6-8 hours, more preferably 6.5-8 hours;
thirdly, drying the second dried product to obtain a third dried product; the temperature of the third drying is preferably 0 to 5 ℃, more preferably 0 ℃, and the vacuum degree of the third drying is preferably 1 to 30Pa, more preferably 1Pa; the heat preservation and pressure maintaining time of the third drying is preferably 10-12 h, more preferably 12h;
fourth drying is carried out on the third dried product to obtain a fourth dried product; the temperature of the fourth drying is preferably 8-12 ℃, more preferably 8.5-11 ℃; the fourth drying vacuum degree is preferably 1 to 30Pa, more preferably 1Pa; the heat preservation and pressure maintaining time of the fourth drying is preferably 48 hours;
Fifth drying the fourth dried product; the temperature of the fifth drying is preferably 16-24 ℃, more preferably 18-22 ℃; the vacuum degree of the fifth drying is preferably 1 to 30Pa, more preferably 1Pa; the holding time for the fifth drying is preferably 48h.
According to the invention, the hydrophilic oleophobic nanocellulose-based filter membrane with high porosity can be obtained by the staged drying, so that the efficiency of oil-water separation is improved.
The invention provides the hydrophilic oleophobic nanocellulose-based filter membrane prepared by the preparation method, which is a reticular structure membrane formed by intertwining nanocellulose.
In the present invention, the hydrophilic oleophobic nanocellulose-based filter membrane porosity is preferably 85-95%.
In the present invention, the hydrophilic oleophobic nanocellulose-based filter membrane is preferably 35cm×50cm×1.5cm in size.
In the invention, the hydrophilic oleophobic nanocellulose-based filter membrane is formed by intertwining nanocellulose to form a net-shaped structure membrane, and the nanocellulose fibrils are arranged in a spiral manner, and the chemical component is glucose, so that the hydrophilic oleophobic nanocellulose-based filter membrane can be degraded in soil by fungi, mould, bacteria and other microorganisms after being used, and the degradation process is similar to that of leaves.
In the invention, the hydrophilic oleophobic nano-cellulose-based filter membrane has a three-dimensional network structure, and the hydrophilic oleophobic membrane realizes oil-water separation after the cellulose wets and swells.
In the present invention, the hydrophilic oleophobic nanocellulose-based filter membrane preferably performs the oil-water separation using the filtration separation device shown in fig. 1.
The invention provides a filtering and separating device, as shown in figure 1, which comprises a separating box 1, a first recovery box 3 and a nanocellulose-based filter membrane 2, wherein the separating box 1 is positioned above the first recovery box 3 and is fixedly connected with the first recovery box 3 in a sealing way, the bottom of the separating box 1 is communicated with the top of the first recovery box 3 through an opening, a filter plate 4 is covered at the opening, the filter plate 4 is provided with a filter hole 7, the nanocellulose-based filter membrane 2 is covered above the filter plate 4, the nanocellulose-based filter membrane 2 can enable water in the separating box 1 to pass through and flow to the first recovery box 3, an inlet 5 is formed in the top surface of the separating box 1, an outlet 6 is formed in one side surface of the separating box 1, the outlet 6 is used for discharging oil liquid with the density smaller than that of water, the separating box 1 is fixedly sealed above the first recovery box 3, an oil-water mixture is poured into the separating box 1 from the inlet 5, and the oil liquid naturally floats on the upper layer of water according to the density difference of the water and the water to achieve the layering purpose; the nanocellulose-based filter membrane 2 is completely paved on the filter plate 4, and the nanocellulose-based filter membrane 2 allows water to pass through and blocks oil liquid from passing through, so that only water can pass through the nanocellulose-based filter membrane 2 and the filter holes 7 to flow from the separation tank 1 to the first recovery tank 3 under the action of simple gravity in the separation tank 1, and the purpose of separating the oil and water mixture is achieved.
In the invention, the filtering and separating device further comprises the slow flow plate 8, the slow flow plate 8 is parallel to the filter plate 4, two ends of the slow flow plate 8 are fixedly arranged on two opposite inner side walls of the separating box 1, which are not provided with the outlet 6, and the slow flow plate 8 can weaken the physical impact of the oil-water mixture flowing from the inlet 5 on the nano cellulose-based filter membrane 2, so that the problem that the nano cellulose-based filter membrane 2 is damaged and can not be filtered and separated due to the fact that the inflow speed of the oil-water mixture is too high.
In the invention, the filtering and separating device further comprises a connecting pipe 12 and a second recovery tank 9, the outlet 6 is in sealing connection and communication with one end of the connecting pipe 12, the other end of the connecting pipe 12 is used for being communicated with the second recovery tank 9, the second recovery tank 9 is used for collecting oil liquid with density smaller than that of water, the layered oil-water mixture flows to the first recovery tank 3, the oil liquid is remained in the separating tank 1, when the liquid level of the oil liquid reaches the outlet 6, the oil liquid flows into the second recovery tank 9 from the outlet 6, and the space in the separating tank 1 is ensured to be filled with a new oil-water mixture all the time.
In the invention, the bottom of the first recovery tank 3 is provided with the water outlet 10, and when the first recovery tank 3 is filled with water or all the oil-water mixture is filtered, the water outlet 10 can be opened so as to be convenient for discharging the water in the first recovery tank 3.
According to the invention, the thickness of the slow flow plate 8 is larger than 5cm, the area of the slow flow plate 8 is 60% -85% of the area of the filter plate 4, the inlet 5 is positioned right above the slow flow plate 8, when the oil-water mixture flows into the separation box 1 from the inlet 5, the slow flow plate 8 positioned right below the inlet 5 can play a good role in buffering the oil-water mixture, and the thickness and the area of the slow flow plate 8 can be automatically adjusted according to actual use.
In the invention, the height of the slow flow plate 8 is lower than the lowest point of the outlet 6, so that the oil-water mixture flowing down from the slow flow plate 8 is prevented from flowing to the outlet 6, and the separation effect of the oil-water mixture is prevented from being influenced.
According to the invention, the emptying port 11 is formed in the side surface of the separation tank 1, the emptying port 11 is provided with the switch, the switch can control the emptying port 11 to be opened and closed, the emptying port 11 is close to the filter plate 4, the emptying port 11 is formed in the separation tank 1 and is close to the bottom of the filter plate 4, the closer the emptying port 11 is to the bottom of the filter plate 4, the better the closer the distance is, the switch can be opened after the filtration of the oil-water mixture is finished, so that the residual oil liquid below the outlet 6 in the separation tank 1 can be quickly and completely discharged, and the emptying port 11 can be connected with a hose or a faucet according to actual use requirements, and the oil liquid is conveniently discharged.
The invention preferably adopts the filtering and separating device to separate the oil from the water, and simultaneously adopts the hydrophilic oleophobic nanocellulose-based filter membrane according to the technical scheme of the invention, so that continuous filtration can be realized, the volume of a continuous filtration oil-water mixture is more than or equal to 100L, and the service time can reach 10 hours. Therefore, the hydrophilic oleophobic nanocellulose-based filter membrane provided by the invention can realize large-scale continuous circulating filtration, does not need a power device, does not consume extra energy, and can realize large-scale continuous circulating filtration by utilizing gravity.
In the present invention, the hydrophilic oleophobic nanocellulose-based filter is preferably reusable, and before use, the hydrophilic oleophobic nanocellulose-based filter is preferably washed.
In the invention, when the hydrophilic oleophobic nanocellulose-based filter membrane is used until cracks and other influences occur on the use condition, the washed hydrophilic oleophobic nanocellulose-based filter membrane is recycled, and the hydrophilic oleophobic nanocellulose-based filter membrane is prepared.
In the invention, the recycling includes the following steps:
crushing the washed waste hydrophilic oleophobic nanocellulose-based filter membrane to obtain a recovered cellulose suspension;
Ultrasonically crushing the recovered cellulose suspension to obtain a recovered nanocellulose solution;
forming a film from the recovered nanocellulose solution to obtain a recovered liquid film; the mass percentage of the recycled nano cellulose solution is more than or equal to 1 percent;
and drying the recovered liquid membrane to obtain the recovered hydrophilic oleophobic nanocellulose-based filter membrane.
In the present invention, the pulverization is preferably performed in a beater, and there is no particular requirement for the specific implementation of the pulverization.
In the invention, the operation parameters of the ultrasonic crushing of the recycled cellulose suspension, the film forming of the recycled nanocellulose solution and the drying of the recycled liquid film are the same as those of the preparation of the hydrophilic oleophobic nanocellulose-based filter film by adopting the biomass material powder in the technical scheme, and are not repeated one by one again.
The invention provides a composite nano cellulose-based filtering membrane, which comprises a first supporting membrane, a nano cellulose membrane and a second supporting membrane which are sequentially laminated; the nano-cellulose membrane is the hydrophilic oleophobic nano-cellulose-based filter membrane according to the technical scheme.
In the present invention, the first support film is preferably a nylon fiber web, the mesh size of the nylon fiber web is preferably 4 to 10mm, and the web thickness of the nylon fiber web is preferably 1 to 3mm.
In the present invention, the second support film is preferably a nylon fiber web, the mesh size of the nylon fiber web is preferably 4 to 10mm, and the web thickness of the nylon fiber web is preferably 1 to 3mm.
The first support membrane and the second support membrane are preferably adopted to enhance the mechanical properties of the hydrophilic oleophobic nanocellulose-based filter membrane, so that a large number of rapid filtering effects can be realized.
The invention provides the application of the hydrophilic oleophobic nanocellulose-based filter membrane in the technical scheme or the composite nanocellulose-based filter membrane in the oil-water mixture separation.
In the invention, the hydrophilic oleophobic nanocellulose-based filter membrane can realize the filtration of an oil-water mixture with the volume of 20-100L for single filtration, and the oil-water separation is carried out; the use time of the hydrophilic oleophobic nanocellulose-based filter membrane provided by the invention can reach 10 hours.
In the invention, the oil-water ratio in the oil-water mixture is 1 (1-5).
In the present invention, the filtration rate of the hydrophilic oleophobic nanocellulose-based filter membrane is preferably 0.025 to 0.05g/cm 2 。
In the invention, the total service time of the hydrophilic oleophobic nanocellulose-based filter membrane is 10 hours.
In the present invention, the total use time length of the composite nanocellulose-based filtration membrane is preferably 1 to 2 hours longer than the total use time length of the hydrophilic oleophobic nanocellulose-based filtration membrane.
The hydrophilic oleophobic nanocellulose-based filter membrane provided by the invention has wide sources of preparation materials, and can solve the problems of agricultural straws and the like. The nano cellulose-based filter membrane after filtration can be completely degraded, is free from environmental pollution, is beneficial to carbon fixation circulation, and is simple and convenient in preparation mode.
The technical solutions provided by the present invention are described in detail below with reference to the drawings and examples for further illustrating the present invention, but they should not be construed as limiting the scope of the present invention.
Example 1
(1) Grinding poplar into powder, and sieving with a 40 mesh sieve to obtain poplar powder;
(2) Adding 1500mL of water into 30g of poplar powder, adding 15g of sodium chlorite and 3g of glacial acetic acid, placing the mixture into a water bath kettle at 50 ℃, heating for 5 hours, and supplementing 15g of sodium chlorite and 3g of glacial acetic acid every 2 hours in the heating process to ensure that the pH value of the mixture is 1;
(3) After heating, washing the acid-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain acid-treated powder;
(4) Adding 500mL of water again to 30g of acid treatment powder, adding 40g of potassium hydroxide, and heating the mixture in a water bath kettle at 70 ℃ for 1 hour;
(5) After heating, washing the alkali-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain alkali-treated powder;
(6) Adding 1500mL of water into the alkali treatment powder again, adding 15g of sodium chlorite and 3g of glacial acetic acid, placing the mixture into a water bath kettle at 50 ℃, heating for 3 hours, and supplementing 15g of sodium chlorite and 3g of glacial acetic acid every 2 hours in the heating process to ensure that the pH value of the mixture is 1;
(7) After heating, washing the acid-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain acid-treated powder;
(8) Adding 500mL of water into the acid treatment powder again, adding 40g of potassium hydroxide, and heating the mixture in a water bath kettle at 70 ℃ for 1 hour;
(9) After heating, washing alkali-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain cellulose powder;
(10) Adding water into cellulose powder to prepare cellulose suspension with the mass percentage of 0.5%;
(11) Using an ultrasonic cell disruption instrument with the power of 600W, carrying out ultrasonic treatment on 500mL of cellulose suspension each time, and carrying out whole-course circulation on the cellulose suspension in an ice-water bath with the temperature of 2-6 ℃ in the ultrasonic process for 25min to obtain a nano cellulose solution with the mass percentage content of 1%;
(12) 1000mL of nanocellulose solution is poured into a square plate with the length of 35cm multiplied by 50cm multiplied by 1.5cm, pre-frozen for 8 hours at the temperature of minus 20 ℃, and then put into a freeze dryer; the procedure of the freeze dryer is set as follows, the first stage is set to a temperature of minus 30 ℃ for freezing for 8 hours, the second stage is started to vacuumize, the temperature of minus 8 ℃ is set to 1Pa, the vacuum degree is set to 6 hours, then the temperature is set to zero, the vacuum degree is set to 1Pa, the operation is carried out for 12 hours, the temperature is set to 8 ℃, the vacuum degree is set to 1Pa, the operation is carried out for 48 hours, the temperature is set to 16 ℃, the vacuum degree is set to 1Pa, and the operation is carried out for 48 hours. The whole process is operated for 122 hours, and the hydrophilic oleophobic nanocellulose-based filter membrane with the length of 35cm multiplied by 50cm multiplied by 1cm is obtained.
Test example 1
FIG. 2 is a physical diagram of a hydrophilic oleophobic nanocellulose-based filter membrane prepared in this embodiment. As can be seen from fig. 2, the hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1 is wound with nanocellulose to form a three-dimensional network structure, and the macroscopic angle is extremely the nanocellulose-based filter membrane.
Specific surface area of hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1 was tested:
(1) Test equipment: the model of the adsorption and specific surface area tester is BELSORP-max; an electronic balance, model XS205;
(2) Environmental conditions: temperature: 24.6 ℃, humidity: 60% RH;
(3) Reference standard: GB/T19587-2017 gas adsorption BET method for measuring specific surface area of solid substance;
(4) Test conditions: a) Pretreatment (vacuum degassing at 120 ℃ C. For 12 hours); b) Nitrogen adsorption (Cross-sectional area 0.162 nm) 2 Purity 99.999%), multipoint testing by a capacity method; c) Saturated vapor pressure at 77.3K of liquid nitrogen was 101.325kPa.
(5) Test results: FIG. 3 is an N-type hydrophilic oleophobic nanocellulose-based Filter membrane prepared in example 1 of the present invention 2 An adsorption graph; FIG. 4 is a BET curve of a hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1 of the present invention; when the sample mass of the hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1 is 0.0852g, the specific surface area of the hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1 is 8.37m 2 /g。
Example 2
(1) Grinding poplar into powder, and sieving with a 40 mesh sieve to obtain poplar powder;
(2) Adding 1500mL of water into 30g of poplar powder, adding 15g of sodium chlorite and 3g of glacial acetic acid, placing the mixture into a water bath kettle at 80 ℃, heating for 8 hours, and supplementing 15g of sodium chlorite and 3g of glacial acetic acid every 2 hours in the heating process to ensure that the pH value of the mixture is 1;
(3) After heating, washing the acid-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain acid-treated powder;
(4) Adding 500mL of water again to 30g of acid treatment powder, adding 40g of potassium hydroxide, and heating the mixture in a water bath kettle at 98 ℃ for 5 hours;
(5) After heating, washing the alkali-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain alkali-treated powder;
(6) Adding 1500mL of water into the alkali treatment powder again, adding 15g of sodium chlorite and 3g of glacial acetic acid, placing the mixture into a water bath kettle at 80 ℃, heating for 5 hours, and supplementing 15g of sodium chlorite and 3g of glacial acetic acid every 2 hours in the heating process to ensure that the pH value of the mixture is 1;
(7) After heating, washing the acid-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain acid-treated powder;
(8) Adding 500mL of water into the acid treatment powder again, adding 40g of potassium hydroxide, and heating the mixture in a water bath kettle at 98 ℃ for 5 hours;
(9) After heating, washing alkali-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain cellulose powder;
(10) Adding water into cellulose powder to prepare cellulose suspension with the mass percentage of 2%;
(11) Using an ultrasonic cell disruption instrument with the power of 900W, carrying out ultrasonic treatment on 1000mL of cellulose suspension each time, and circulating 2-6 ℃ ice water bath in the whole ultrasonic process for 45min to obtain a nano cellulose solution with the mass percentage content of 2.5%;
(12) 2000mL of nanocellulose solution is poured into a square plate of 35cm multiplied by 50cm multiplied by 1.5cm, pre-frozen for 14 hours at minus 30 ℃, and then put into a freeze dryer; the procedure of the freeze dryer is set as follows, the first stage is set to freeze at-50 ℃ for 10 hours, the second stage is started to vacuumize, the temperature is set to-12 ℃, the vacuum degree is 1Pa, the operation is carried out for 6 hours, then the temperature is set to zero, the vacuum degree is 1Pa, the operation is carried out for 12 hours, the temperature is set to 12 ℃, the vacuum degree is 1Pa, the operation is carried out for 48 hours, the temperature is set to 24 ℃, the vacuum degree is 1Pa, and the operation is carried out for 48 hours. The whole process is operated for 126 hours, and the hydrophilic oleophobic nanocellulose-based filter membrane with the length of 35cm multiplied by 50cm multiplied by 1cm is obtained.
Comparative example 1
(1) Grinding poplar into powder, and sieving with a 40 mesh sieve to obtain poplar powder;
(2) Adding 1500mL of water into 30g of poplar powder, adding 15g of sodium chlorite and 3g of glacial acetic acid, placing the mixture into a water bath kettle at 50 ℃, heating for 5 hours, and supplementing 15g of sodium chlorite and 3g of glacial acetic acid every 2 hours in the heating process to ensure that the pH value of the mixture is 1;
(3) After heating, washing the acid-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain acid-treated powder;
(4) Adding 500mL of water again to 30g of acid treatment powder, adding 40g of potassium hydroxide, and heating the mixture in a water bath kettle at 70 ℃ for 1 hour;
(5) After heating, washing the alkali-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain alkali-treated powder;
(6) Adding 1500mL of water into the alkali treatment powder again, adding 15g of sodium chlorite and 3g of glacial acetic acid, placing the mixture into a water bath kettle at 50 ℃, heating for 3 hours, and supplementing 15g of sodium chlorite and 3g of glacial acetic acid every 2 hours in the heating process to ensure that the pH value of the mixture is 1;
(7) After heating, washing the acid-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain acid-treated powder;
(8) Adding 500mL of water into the acid treatment powder again, adding 40g of potassium hydroxide, and heating the mixture in a water bath kettle at 70 ℃ for 1 hour;
(9) After heating, washing alkali-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain cellulose powder;
(10) Adding water into cellulose powder to prepare cellulose suspension with the mass percentage of 0.5%;
(11) Using an ultrasonic cell disruption instrument with the power of 600W, carrying out ultrasonic treatment on 500mL of cellulose suspension each time, and carrying out whole-course circulation on the cellulose suspension in an ice-water bath with the temperature of 2-6 ℃ in the ultrasonic process for 25min to obtain a nano cellulose solution with the mass percentage content of 0.5%;
(12) 700mL of nanocellulose solution is poured into a square plate with the length of 35cm multiplied by 50cm multiplied by 1.5cm, pre-frozen for 8 hours at the temperature of minus 20 ℃, and then put into a freeze dryer; the procedure of the freeze dryer is set as follows, the first stage is set to a temperature of minus 30 ℃ for freezing for 8 hours, the second stage is started to vacuumize, the temperature of minus 8 ℃ is set to 1Pa, the vacuum degree is set to 6 hours, then the temperature is set to zero, the vacuum degree is set to 1Pa, the operation is carried out for 12 hours, the temperature is set to 8 ℃, the vacuum degree is set to 1Pa, the operation is carried out for 48 hours, the temperature is set to 16 ℃, the vacuum degree is set to 1Pa, and the operation is carried out for 48 hours. The whole process is operated for 122 hours, and the hydrophilic oleophobic nanocellulose-based filter membrane with the length of 35cm multiplied by 50cm multiplied by 1cm is obtained.
Comparative example 2
(1) Grinding poplar into powder, and sieving with a 40 mesh sieve to obtain poplar powder;
(2) Adding 1500mL of water into 30g of poplar powder, adding 15g of sodium chlorite and 3g of glacial acetic acid, placing the mixture into a water bath kettle at 50 ℃, heating for 5 hours, and supplementing 15g of sodium chlorite and 3g of glacial acetic acid every 2 hours in the heating process to ensure that the pH value of the mixture is 1;
(3) After heating, washing the acid-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain acid-treated powder;
(4) Adding 500mL of water again to 30g of acid treatment powder, adding 40g of potassium hydroxide, and heating the mixture in a water bath kettle at 70 ℃ for 1 hour;
(5) After heating, washing the alkali-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain alkali-treated powder;
(6) Adding 1500mL of water into the alkali treatment powder again, adding 15g of sodium chlorite and 3g of glacial acetic acid, placing the mixture into a water bath kettle at 50 ℃, heating for 3 hours, and supplementing 15g of sodium chlorite and 3g of glacial acetic acid every 2 hours in the heating process to ensure that the pH value of the mixture is 1;
(7) After heating, washing the acid-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain acid-treated powder;
(8) Adding 500mL of water into the acid treatment powder again, adding 40g of potassium hydroxide, and heating the mixture in a water bath kettle at 70 ℃ for 1 hour;
(9) After heating, washing alkali-treated powder obtained by solid-liquid separation with distilled water to neutrality to obtain cellulose powder;
(10) Adding water into cellulose powder to prepare cellulose suspension with the mass percentage of 1%;
(11) Using an ultrasonic cell disruption instrument with the power of 600W, carrying out ultrasonic treatment on 500mL of cellulose suspension each time, and carrying out whole-course circulation on the cellulose suspension in an ice-water bath with the temperature of 2-6 ℃ in the ultrasonic process for 25min to obtain a nano cellulose solution with the mass percentage content of 1%;
(12) 1000mL of nanocellulose solution is poured into a square plate with the length of 35cm multiplied by 50cm multiplied by 1.5cm, pre-frozen for 8 hours at the temperature of minus 20 ℃, and then put into a freeze dryer; the procedure of the freeze dryer is set as follows, the first stage is set to a temperature of minus 30 ℃ for 5 hours, the second stage is started to vacuumize, the vacuum degree is set to minus 8 ℃ for 1Pa, the operation is carried out for 5 hours, then the zero degree is set, the vacuum degree is set to 1Pa, the operation is carried out for 8 hours, the vacuum degree is set to 8 ℃ for 1Pa, the operation is carried out for 24 hours, the vacuum degree is set to 16 ℃ for 1Pa, and the operation is carried out for 24 hours. The whole process is operated for 66 hours, and the hydrophilic oleophobic nanocellulose-based filter membrane with the length of 35cm multiplied by 50cm multiplied by 1cm is obtained.
Application example 1
The hydrophilic oleophobic nanocellulose-based filters prepared in example 1, comparative example 2 and comparative example 2 were subjected to oil-water separation using the apparatus shown in fig. 1, respectively, wherein the treatment volume of the oil-water mixture was 40mL, and the mass ratio of oil to water in the oil-water mixture was 1:1;
The hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1 can successfully complete an oil-water separation experiment, and the filtering speed is 0.05g/cm 2 ；
The hydrophilic oleophobic nanocellulose-based filter membrane prepared in comparative example 1 is broken and fractured in the filtration process due to poor mechanical strength, so that filtration is difficult to complete;
the hydrophilic oleophobic nanocellulose-based filter membrane prepared in comparative example 2 had a filtration rate of only 0.005g/cm due to too short drying time, and residual moisture in the filter membrane 2 。
Application example 2
Placing a layer of nylon fiber net on two side surfaces of the hydrophilic oleophobic nano-cellulose-based filter membrane prepared in the embodiment 1 respectively, wherein the mesh size of the nylon fiber net is 4mm, and the net thickness of the nylon fiber net is 1mm, so as to obtain a composite nano-cellulose-based filter membrane;
carrying out oil-water separation on the composite nano cellulose-based filtering membrane by adopting the device shown in the figure 1, wherein the treatment volume of an oil-water mixture is 40mL, and the mass ratio of oil to water in the oil-water mixture is 1:1; the total duration of use of the composite nanocellulose-based filter membrane was 2 hours longer than the total duration of use of the hydrophilic oleophobic nanocellulose-based filter membrane prepared in example 1.
Example 3
The hydrophilic oleophobic nano-cellulose-based filter membrane prepared in the example 1 is used until cracks and the like affect the use condition, and the washed cellulose-based filter membrane is crushed by a beater to obtain a recovered cellulose suspension with the mass percent of 0.5%; the ultrasonic cell disruption instrument is utilized, the power is 600W watts, 500mL of recovered cellulose suspension is treated by ultrasonic every time, the whole process of ultrasonic treatment is circulated in 2-6 ℃ of ice water bath, the treatment time is 25min, and the recovered nanocellulose solution with the mass percentage content of 1 percent is obtained;
Pouring 1000mL of the recovered nanocellulose solution into a square plate of 35cm multiplied by 50cm multiplied by 1.5cm, pre-freezing for 8 hours at the temperature of minus 20 ℃, and then placing into a freeze dryer; the procedure of the freeze dryer is set as follows, the first stage is set to a temperature of minus 30 ℃ for freezing for 8 hours, the second stage is started to vacuumize, the temperature of minus 8 ℃ is set to 1Pa, the vacuum degree is set to 6 hours, then the temperature is set to zero, the vacuum degree is set to 1Pa, the operation is carried out for 12 hours, the temperature is set to 8 ℃, the vacuum degree is set to 1Pa, the operation is carried out for 48 hours, the temperature is set to 16 ℃, the vacuum degree is set to 1Pa, and the operation is carried out for 48 hours. The whole process is operated for 122 hours, and the 35cm multiplied by 50cm multiplied by 1cm hydrophilic oleophobic nanocellulose-based filter membrane prepared by the abandoned nanocellulose-based filter membrane after the use of the embodiment 1 is obtained, and the filtering effect can still be realized.
Although the foregoing embodiments have been described in some, but not all embodiments of the invention, other embodiments may be obtained according to the present embodiments without departing from the scope of the invention.
Claims (10)
1. The preparation method of the hydrophilic oleophobic nanocellulose-based filter membrane is characterized by comprising the following steps of:
removing lignin and hemicellulose from the biomass material powder to obtain cellulose powder;
Dispersing the cellulose powder in water to obtain a cellulose suspension;
ultrasonically crushing the cellulose suspension to obtain a nanocellulose solution;
forming a film from the nanocellulose solution to obtain a liquid film; the mass percentage of the nano cellulose solution is more than or equal to 1 percent;
and drying the liquid membrane to obtain the hydrophilic oleophobic nanocellulose-based filter membrane.
2. The method according to claim 1, wherein the drying temperature is not higher than 24 ℃, and the drying holding time is not lower than 120 hours.
3. The method of preparation according to claim 1 or 2, wherein the drying comprises the steps of:
performing first drying on the liquid film to obtain a first dried product; the temperature of the first drying is-30 to-50 ℃, and the heat preservation time of the first drying is 8-10 h;
performing second drying on the first dried product to obtain a second dried product; the temperature of the second drying is-8 to-12 ℃, the vacuum degree of the second drying is 1-30 Pa, and the heat preservation and pressure maintaining time of the second drying is 6-8 h;
thirdly, drying the second dried product to obtain a third dried product; the temperature of the third drying is 0-5 ℃, the vacuum degree of the third drying is 1-30 Pa, and the heat preservation and pressure maintaining time of the third drying is 10-12 h;
Fourth drying is carried out on the third dried product to obtain a fourth dried product; the temperature of the fourth drying is 8-12 ℃, the vacuum degree of the fourth drying is 1-30 Pa, and the heat preservation and pressure maintaining time of the fourth drying is 48 hours;
fifth drying the fourth dried product; the temperature of the fifth drying is 16-24 ℃, the vacuum degree of the fifth drying is 1-30 Pa, and the heat preservation and pressure maintaining time of the fifth drying is 48h.
4. The method according to claim 1, wherein the power of the ultrasonic crushing is 600 to 900W, and the time of the ultrasonic crushing is 25 to 45min; the temperature of the ultrasonic crushing is 2-6 ℃.
5. The method according to claim 1 or 4, wherein the mass percentage of the cellulose suspension is 0.5 to 2%.
6. The method of claim 1, wherein the removing lignin and hemicellulose comprises the steps of:
mixing the biomass material powder, water, sodium chlorite and glacial acetic acid for first acid treatment to obtain first acid treatment powder;
mixing the first acid treatment powder, water and inorganic strong base to perform first alkali treatment to obtain first alkali treatment powder;
Mixing the first alkali treatment powder, water, sodium chlorite and glacial acetic acid to perform second acid treatment to obtain second acid treatment powder;
and mixing the second acid treatment powder, water and inorganic strong base for second alkali treatment to obtain the cellulose powder.
7. The method according to claim 6, wherein the mass ratio of the biomass material powder, sodium chlorite and glacial acetic acid is (10-40): 9-20): 3;
when the first alkali treatment is carried out, the mass ratio of the biomass material powder to the inorganic strong alkali is 3 (2.5-5);
the temperature of the first acid treatment and the second acid treatment are independently 50-80 ℃, and the heat preservation time of the first acid treatment and the second acid treatment is independently 5-8 h;
the temperature of the first alkali treatment and the second alkali treatment are independently 70-98 ℃, and the heat preservation time of the first alkali treatment and the second alkali treatment is independently 1-5 h.
8. The hydrophilic oleophobic nanocellulose-based filter membrane prepared by the preparation method of any one of claims 1 to 7, wherein the hydrophilic oleophobic nanocellulose-based filter membrane is a reticular membrane formed by intertwining nanocellulose.
9. The composite nano cellulose-based filtering membrane is characterized by comprising a first supporting membrane, a nano cellulose membrane and a second supporting membrane which are sequentially laminated; the nanocellulose membrane is the hydrophilic oleophobic nanocellulose-based filter membrane of claim 8.
10. Use of the hydrophilic oleophobic nanocellulose-based filter membrane of claim 8 or the composite nanocellulose-based filter membrane of claim 9 in separation of oil-water mixtures.
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| CN104592743A (en) * | 2015-02-03 | 2015-05-06 | 东北林业大学 | Preparation method of nanocellulose/polyurethane foam composite elastomer |
| CN105935502A (en) * | 2016-05-10 | 2016-09-14 | 上海澍澎新材料科技有限公司 | Super hydrophilic and underwater super oleophobic oil-water separation screen film and production method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104592743A (en) * | 2015-02-03 | 2015-05-06 | 东北林业大学 | Preparation method of nanocellulose/polyurethane foam composite elastomer |
| CN105935502A (en) * | 2016-05-10 | 2016-09-14 | 上海澍澎新材料科技有限公司 | Super hydrophilic and underwater super oleophobic oil-water separation screen film and production method thereof |
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