CN113845667A - Preparation method and application of oxidized nano cellulose pickering emulsion - Google Patents

Preparation method and application of oxidized nano cellulose pickering emulsion Download PDF

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CN113845667A
CN113845667A CN202111285929.XA CN202111285929A CN113845667A CN 113845667 A CN113845667 A CN 113845667A CN 202111285929 A CN202111285929 A CN 202111285929A CN 113845667 A CN113845667 A CN 113845667A
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bagasse
cellulose
oxidized
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东为富
蒋杰
黄晶
汪洋
李婷
张旭辉
夏碧华
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Jiangnan University
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Abstract

The invention relates to a preparation method and application of oxidized nanocellulose pickering emulsion, belonging to the technical field of biological nano materials. The sodium periodate can be oxidized by introducing aldehyde group to regulate the hydrophilicity and hydrophobicity of the bagasse nanocellulose. The carboxyl content of the oxidized bagasse cellulose is 0.5-1.8mmol/g, the aldehyde group content is 0.1-2.0mmol/g, the prepared bagasse nanocellulose with high length-diameter ratio can be used as a solid emulsifier and stably exists at an oil-water interface of the pickering emulsion, and when the volume ratio of an oily solvent to a nanocellulose dispersion liquid is 1:5-2:1, the prepared pickering emulsion does not have the phenomenon of stability reduction after being stored at room temperature for a long time.

Description

Preparation method and application of oxidized nano cellulose pickering emulsion
Technical Field
The invention belongs to the technical field of biological nano materials, and particularly relates to a preparation method and application of oxidized nano cellulose pickering emulsion.
Background
The pickering emulsion is a stable dispersed emulsion which uses solid particles to replace a traditional surfactant as a stabilizer to form a barrier thin layer at an oil-water two-phase interface. Compared with the traditional surfactant stable emulsion, the pickering emulsion has the advantages of low emulsifier dosage, high stability, small toxic action on human bodies, high environmental friendliness and the like.
The cellulose is a biomass polymer with the largest reserve in nature, the cellulose fiber has a multilayer structure, and the microfibrillation of the cellulose fiber can be realized through simple chemical modification and mechanical treatment, so that the nano-cellulose with the diameter lower than 100 nanometers is prepared. The cellulose molecules are orderly arranged, the crystal structure endows the cellulose with natural amphipathy, and the nanocellulose has a good function of stabilizing the Pickering emulsion. As one of the main sources of cellulose, a large amount of herbal wood fiber is burned, causing waste of herbal cellulose resources while polluting the environment.
The invention patent CN201210270166.6 discloses a method for preparing Pickering emulsion by using oxidized bacterial cellulose, and discloses a method for preparing nano-cellulose by using high-pressure homogenization treatment of aldehyde-based bacterial cellulose and preparing stable Pickering emulsion by using the nano-cellulose as a solid emulsifier. However, the method described in this patent requires a long culture period and a low yield of the bacterial cellulose material, and the high-pressure homogenization treatment method requires a large amount of energy and requires a high production cost. On the other hand, chinese patent CN201810618899.1 discloses a method for preparing nano-crystalline cellulose emulsion, which discloses a method for improving the stability of methyl oleate or epoxy soybean oil emulsion by applying nano-crystalline cellulose in acidic solution. However, in the above method, the short rod-like nanocrystalline cellulose having a relatively low long diameter ratio prepared by acid hydrolysis is used as a raw material, and the amount used in the process of stabilizing the emulsion is higher than that of the fibrous nanocellulose having a larger long diameter ratio.
In the related art, document 1: "pickering methyl methacrylate emulsion prepared using sisal nanocellulose as solid emulsifier" and document 2: the rapeseed oil Pickering emulsion prepared by using the softwood nano-cellulose has the defects of low morphological and dimensional uniformity and overlarge particle size of the nano-cellulose. Document 3: the dodecane pickering emulsion prepared by applying the cellulose nanowhiskers has the defect of low stability.
Disclosure of Invention
Aiming at the defects of the emulsion in the related technology, the invention provides a preparation method and application of oxidized nano cellulose Pickering emulsion.
As an aspect of the present invention, there is provided a method of oxidizing nanocellulose pickering emulsion, comprising:
(a) carrying out cooking pretreatment, bleaching treatment and dilute alkali liquor soaking treatment on the bagasse to remove lignin and hemicellulose in the bagasse, and fully cleaning to obtain purified bagasse cellulose;
(b) TEMPO oxidation modification or TEMPO oxidation combined with sodium periodate oxidation modification is carried out on the bagasse cellulose to respectively obtain TEMPO oxidized bagasse cellulose or sodium periodate modified TEMPO oxidized bagasse cellulose;
(c) dispersing TEMPO oxidized bagasse cellulose or sodium periodate modified TEMPO oxidized bagasse cellulose in neutral or alkalescent aqueous solution to form suspension, and mechanically treating the suspension to obtain aqueous phase dispersion; then removing undispersed fibers and flocculated parts in the aqueous phase dispersion liquid by a centrifugation or filtration method to obtain supernatant;
(d) mixing an oily solvent and the supernatant to obtain a mixed system, and carrying out high-speed homogenization or ultrasonic dispersion on the mixed system to obtain a stable pickering emulsion; wherein the volume mixing ratio of the oily solvent to the supernatant is 1:5-2: 1.
In an achievable embodiment, the bagasse cooking pretreatment is performed in a mixed solution of sulfurous acid and acid sulfite.
In one embodiment, the bleaching treatment is bleaching with chlorite or laccase.
In one embodiment, the TEMPO oxidative modification of bagasse cellulose comprises: dispersing bagasse cellulose in a solution in which TEMPO and sodium bromide are dissolved, adding an oxidant sodium hypochlorite of 2-10mmol/g cellulose, selectively oxidizing C6 primary hydroxyl of the bagasse cellulose at 20-40 ℃, dropwise adding a sodium hydroxide solution in the oxidation process to maintain the pH of a mixed system to be stable at about 10, adding ethanol to terminate the reaction after the pH does not decrease any more, repeatedly centrifuging or filtering water-insoluble substances in the cleaning system by using distilled water, and cleaning when the conductivity of clear liquid is close to that of the distilled water, wherein the obtained water-insoluble substances are TEMPO oxidized bagasse cellulose.
Further, the carboxyl content of the TEMPO oxidized bagasse cellulose ranges from 0.5 to 1.8mmol/g cellulose.
Further, the TEMPO oxidation combined with sodium periodate oxidation modified TEMPO comprises:
dispersing TEMPO oxidized bagasse cellulose in water, adding sodium periodate with the mass of 0.5-2 times that of the cellulose, carrying out selective ring-opening oxidation of hydroxyl groups at C2 and C3 under dark conditions, keeping the system constantly and uniformly stirred in the oxidation process, wherein the oxidation reaction temperature is 30-60 ℃, the reaction time is 1-24 hours, adding a small amount of glycol to terminate the reaction when the reaction is finished, then repeatedly centrifuging by using distilled water or filtering water-insoluble substances in the cleaning system, and cleaning until the conductivity of clear liquid is close to that of the distilled water, wherein the obtained water-insoluble substances are the sodium periodate modified TEMPO oxidized bagasse cellulose.
Further, the aldehyde group content of the sodium periodate modified TEMPO oxidized bagasse cellulose ranges from 0.1 to 2.0mmol/g cellulose.
Further, the diameter of the bagasse nanocellulose in the supernatant is 2-10nm, and the length of the bagasse nanocellulose is 0.2-10 um.
In one realizable embodiment, the oily solvent comprises, but is not limited to, a single oil phase of liquid paraffin, toluene, castor oil, soybean oil, peanut oil, olive oil, sunflower oil, n-heptane, dodecane, methyl methacrylate, styrene, butyl acrylate, chloroform, or a mixed oil phase thereof.
As another aspect of the invention, the pickering milk obtained by the method is applied to the fields of daily cosmetics, foods, medicines and the like.
Compared with the prior art, the invention has the beneficial effects that:
1. the method for preparing the pickering emulsion by extracting the nano-cellulose from the herb bagasse material as the emulsion stabilizer has the advantages of huge storage amount of raw bagasse, low cost and easy obtainment, and the prepared bagasse nano-cellulose has a higher length-diameter ratio than wood pulp nano-cellulose, so that the using amount can be greatly reduced, and the cost can be saved.
2. According to the invention, single separated oxidized bagasse nanocellulose can be obtained by adopting a TEMPO oxidation and sodium periodate oxidation auxiliary mechanical treatment method, carboxyl and aldehyde groups are introduced on the surface of the nanocellulose through selective oxidation, the hydrophilic and hydrophobic properties of the nanocellulose can be controllably adjusted while high efficiency and high yield are ensured, the stability of the Pickering emulsion prepared by mixing the bagasse nanocellulose with different oil phases is further improved, and the diameter of the emulsion is reduced.
3. The bagasse nanocellulose used in the invention is an environment-friendly renewable biological polysaccharide high polymer material, has good degradability and biocompatibility, and the prepared pickering emulsion has great application potential in the fields of daily cosmetics, foods, medicines and the like.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is an infrared spectrum of bagasse cellulose before and after TEMPO oxidation in example 2;
FIG. 2 is an atomic force microscope image of TEMPO oxidized bagasse nanocellulose from example 2;
FIG. 3 is an atomic force microscope photograph of bagasse nanocellulose prepared in example 3 after TEMPO oxidation and sodium periodate oxidation;
FIG. 4 is an optical microscope photograph of the bagasse nanocellulose/castor oil emulsion in example 4;
FIG. 5 is an optical microscope photograph of (A) a sisal nanocellulose/methylmethacrylate emulsion of comparative example 1; (B) an optical microscopy image of a bagasse nanocellulose/methyl methacrylate emulsion;
FIG. 6 is a particle size distribution diagram of (A) a softwood nanocellulose/rapeseed oil emulsion in comparative example 2; (B) the particle size distribution diagram of the bagasse nano-cellulose/rapeseed oil emulsion;
FIG. 7 is a photograph of (A) a cellulose nanowhisker/dodecane emulsion before and after standing in comparative example 3; (B) photos of bagasse nanocellulose/dodecane emulsion before and after standing.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The sources of reagents used in the examples of the present invention are commercially available except where otherwise specified.
In an embodiment of the invention, a method of making a pickering emulsion using oxidized bagasse cellulose:
(a) adding bagasse raw materials into a mixed solution of sulfurous acid and acid sulfite for cooking pretreatment, adding an acid sodium chlorite solution after cleaning for bleaching to remove residual lignin, immersing the cleaned bagasse raw materials in a dilute alkali solution to remove residual hemicellulose, and finally cleaning to obtain pure bagasse cellulose;
(b) dispersing bagasse cellulose in a solution in which TEMPO and sodium bromide are dissolved, adding an oxidant sodium hypochlorite of 2-10mmol/g cellulose, selectively oxidizing C6 primary hydroxyl of the bagasse cellulose at 20-40 ℃, dropwise adding a sodium hydroxide solution in the oxidation process to maintain the pH of a mixed system to be stable at about 10, adding ethanol to terminate the reaction after the pH does not fall any more, repeatedly centrifuging or filtering water-insoluble substances in the cleaning system by using distilled water, and cleaning when the conductivity of clear liquid is close to that of the distilled water, wherein the obtained water-insoluble substances are TEMPO oxidized bagasse cellulose;
(c) dispersing TEMPO oxidized bagasse cellulose in water, adding sodium periodate with the mass of 0.5-2 times that of the cellulose, carrying out selective ring-opening oxidation of hydroxyl groups at C2 and C3 under dark conditions, keeping the system constantly and uniformly stirred in the oxidation process, wherein the oxidation reaction temperature is 30-60 ℃, the reaction time is 1-24 hours, adding a small amount of glycol to terminate the reaction when the reaction is finished, then repeatedly centrifuging by using distilled water or filtering water-insoluble substances in the cleaning system, and cleaning until the conductivity of clear liquid is close to that of the distilled water, wherein the obtained water-insoluble substances are the sodium periodate modified TEMPO oxidized bagasse cellulose;
(d) dispersing TEMPO oxidized bagasse cellulose or sodium periodate modified TEMPO oxidized bagasse fiber in neutral or alkalescent aqueous solution to form suspension, and mechanically shearing the suspension; obtaining an oxidized bagasse cellulose aqueous phase dispersion liquid, and removing undispersed fibers and flocculated parts by using a centrifugation or filtration method, wherein the supernatant is the bagasse nanocellulose dispersion liquid; the concentration of the bagasse nano-cellulose dispersion is 0.1-1.5%.
(e) Mixing the bagasse nano-cellulose dispersion liquid with an oily solvent, carrying out high-speed homogenization or ultrasonic dispersion treatment on the mixed system to obtain a stable pickering emulsion, and measuring the properties of the emulsion such as size distribution, stability, dispersibility and the like. The volume ratio of the oil phase to the bagasse nanocellulose dispersion in the emulsion is 1:5-2: 1.
Example 1: preparation of purified bagasse cellulose
Adding sulfite bagasse pulp into a sodium chlorite solution with the concentration of 0.6% for uniform dispersion, dropwise adding glacial acetic acid to adjust the pH of the suspension to be below 5, and then placing the mixed system in a water bath at 70 ℃ for bleaching for 2 hours while intermittently stirring. And after the reaction is finished, cleaning the bleached bagasse cellulose by using distilled water. And then adding the bleached bagasse cellulose into a sodium hydroxide solution with the concentration of 8% to soak for X hours to remove hemicellulose, cleaning the purified bagasse cellulose with distilled water, and then placing the cleaned bagasse cellulose in a refrigerator for storage.
Example 2: preparation of TEMPO oxidized bagasse nanocellulose
Weighing 1g of cellulose raw material by dry weight, adding the cellulose raw material into a solution dissolved with 0.1g of sodium bromide and 0.016g of TEMPO, uniformly dispersing, adding 2-10mmol of sodium hypochlorite under stirring to cause the pH of the system to be reduced, and dropwise adding a sodium hydroxide solution to control the pH of the mixed system to be maintained at about 10. And (3) dropping a small amount of ethanol solution into the reaction system to stop the reaction when the pH value of the reaction system does not drop any more, then dropping hydrochloric acid solution to adjust the pH value of the system to be neutral, centrifugally cleaning the oxidized cellulose by using distilled water, pouring supernate, and repeatedly cleaning for more than 4 times, wherein the water-insoluble part is TEMPO oxidized bagasse cellulose. The carboxyl content of the oxidized bagasse cellulose was determined by pH-conductivity titration, and the data is shown in table 1, where the reaction time was prolonged and the carboxyl content of the oxidized bagasse cellulose was continuously increased with the increase of the sodium hypochlorite dosage. The infrared spectrum of the oxidized bagasse cellulose obtained by oxidation with 6mmol of sodium hypochlorite is shown in FIG. 1 at 1750cm-1The absorption peaks of the left and right carboxyl groups are clearly visible, which indicates the effective introduction of the carboxyl group.
0.1g of oxidized bagasse cellulose in dry weight was dispersed in distilled water to prepare a suspension having a concentration of 0.1%, and the oxidized cellulose suspension was treated with an ultrasonic disintegrator for 20 minutes. And after the ultrasonic treatment is finished, centrifuging to remove the precipitate of the undispersed flocculation part, and obtaining supernate, namely the bagasse nano-cellulose dispersion liquid. The morphology of 6mmol sodium hypochlorite oxidized bagasse nanocellulose was determined using atomic force microscopy, as shown in fig. 2, nanocellulose having a diameter of 4-10 nm and a length of up to 1 micron or more, had a high aspect ratio.
TABLE 1 statistical table of oxidation time and carboxyl content of oxidized cellulose under different sodium hypochlorite dosages
Figure BDA0003331648080000051
Figure BDA0003331648080000061
Example 3: preparation and nanocrystallization of sodium periodate-modified TEMPO oxidized bagasse cellulose
Taking 1g TEMPO oxidized bagasse cellulose in dry weight, adding into an acetic acid-sodium acetate buffer solution with pH of 4.6, uniformly dispersing, adding 0.5-2g sodium periodate, placing the mixed system in a water bath at 30-60 ℃ for reaction, and carrying out the reaction in a dark environment. And after oxidizing for 1-24 hours, adding a proper amount of ethylene glycol into the system to terminate the reaction, centrifugally cleaning the oxidized cellulose by using distilled water, pouring out supernate, and repeatedly cleaning for more than 4 times, wherein the water-insoluble part is the sodium periodate modified TEMPO oxidized bagasse cellulose. The aldehyde group content of the oxidized bagasse cellulose was determined by sodium chlorite reoxidation and pH-conductivity titration, and the data are shown in table 2, with the increase in the amount of sodium periodate, the reaction temperature and the reaction time all contributing to the aldehyde group content of the oxidized bagasse cellulose.
0.1g of sodium periodate-modified oxidized cellulose (the amount of sodium periodate is 1.5g, the oxidation temperature is 50 ℃, and the oxidation time is 3 hours) in dry weight is taken and dispersed in distilled water to prepare a suspension with the concentration of 0.1 percent, and the oxidized cellulose suspension is treated for 20 minutes by an ultrasonic crusher. And after the ultrasonic treatment is finished, centrifuging to remove the undispersed flocculated part of the sediment, and obtaining supernatant, namely the sodium periodate modified bagasse nanocellulose dispersion liquid. The morphology of the bagasse nanocellulose was determined using an atomic force microscope, as shown in fig. 3, the morphology of nanocellulose was similar to TEMPO oxidized bagasse nanocellulose, with a high aspect ratio.
TABLE 2 statistical table of aldehyde group content of oxidized bagasse cellulose under different sodium periodate oxidation conditions
Figure BDA0003331648080000062
Figure BDA0003331648080000071
Example 4: preparation of TEMPO oxidized bagasse nanocellulose/castor oil emulsion
Weighing castor oil, adding the castor oil into TEMPO oxidized bagasse nanocellulose dispersion liquid, wherein the volume ratio of the castor oil to the nanocellulose dispersion liquid is 1:2, dispersing an oil-water mixture in an ultrasonic crusher for 1 minute to prepare stable oil-in-water emulsion, and measuring the form of the emulsion by using an optical microscope, wherein the emulsion is uniform in size and form distribution and has a diameter of 3-18 microns as shown in figure 4. The emulsion is kept standing at room temperature, obvious phenomena of demulsification, delamination and aggregation are not observed after 3 months, and the stability of the emulsion is good.
Example 5: preparation of sodium periodate modified bagasse nano-cellulose/soybean oil emulsion
Weighing soybean oil, adding the soybean oil into sodium periodate modified oxidized bagasse nano-cellulose dispersion liquid, wherein the volume ratio of the soybean oil to the nano-cellulose dispersion liquid is 1:1, and dispersing an oil-water mixture in an ultrasonic crusher for 1 minute to prepare the stable oil-in-water emulsion. The emulsion is kept standing at room temperature, obvious phenomena of demulsification, delamination and aggregation are not observed after 3 months, and the stability of the emulsion is good.
The following comparative examples 1 to 3 are comparative experiments set for the related art documents 1 to 3 in the background art:
comparative example 1: form comparison of methyl methacrylate emulsion prepared from sisal hemp nano-cellulose and oxidized bagasse nano-cellulose
In document 1, sisal nanocellulose prepared by acid hydrolysis and having a concentration of 0.3% is used as a solid emulsifier, and an aqueous dispersion and methyl methacrylate are mixed at a volume ratio of 3:1, and then subjected to ultrasonic dispersion to prepare a pickering emulsion, and an optical microscope photograph of the emulsion is shown in fig. 5A. An optical micrograph of the Pickering emulsion prepared by mixing the aqueous dispersion of oxidized bagasse nanocellulose at the same concentration with methyl methacrylate in the same volume ratio is shown in FIG. 5B. As can be seen from the figure, the bagasse nanocellulose/methyl methacrylate emulsion is more uniform in form, smaller in emulsion particle size and better in emulsion dispersion effect.
Comparative example 2: particle size distribution comparison of rapeseed oil emulsion prepared from cork nanocellulose and oxidized bagasse nanocellulose
In document 2, 0.83% nanocellulose prepared by oxidizing softwood pulp with TEMPO is used as a solid emulsifier, and a pickering emulsion is prepared by mixing an aqueous phase dispersion and rapeseed oil in a volume ratio of 3:2 and then performing ultrasonic dispersion, wherein the particle size distribution of the prepared emulsion is shown in fig. 6A. The particle size distribution of the Pickering emulsion prepared by mixing the oxidized bagasse nanocellulose aqueous dispersion with the same concentration and the rapeseed oil according to the same volume ratio is shown in FIG. 6B. It can be seen from the figure that the particle size distribution of the bagasse nanocellulose/rapeseed oil emulsion is smaller and more uniform.
Comparative example 3: stability comparison of dodecane emulsion prepared from cellulose nanowhiskers and oxidized bagasse nanocellulose
In the document 3, a cellulose nanowhisker with a diameter of 15 nm and a length of 100-200 nm at a concentration of 2% is used as a solid emulsifier, and a Pickering emulsion is prepared by ultrasonic dispersion after mixing an aqueous phase dispersion and dodecane at a volume ratio of 1:1, and photographs of the emulsion before and after standing for 15 days are shown in FIG. 7A. The photographs of the pickering emulsion prepared by mixing the aqueous dispersion of oxidized bagasse nanocellulose at a concentration of 0.5% with dodecane at the same volume ratio before and after standing for 30 days are shown in fig. 7B. It can be seen from the figure that the bottom layer of the cellulose nanowhisker/dodecane emulsion appears a little water phase after standing for 15 days, while the pickering emulsion prepared by mixing the bagasse nanowhisker with a lower dosage and dodecane has higher stability and hardly changes after standing for 30 days.
The spirit of the embodiments of the present invention can be changed in the detailed description and the application range, so that the present specification should not be construed as limiting the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (10)

1. A method for oxidizing nanocellulose pickering emulsion is characterized by comprising the following steps:
(a) carrying out cooking pretreatment, bleaching treatment and dilute alkali liquor soaking treatment on the bagasse to remove lignin and hemicellulose in the bagasse, and fully cleaning to obtain purified bagasse cellulose;
(b) TEMPO oxidation modification or TEMPO oxidation combined with sodium periodate oxidation modification is carried out on the bagasse cellulose to respectively obtain TEMPO oxidized bagasse cellulose or sodium periodate modified TEMPO oxidized bagasse cellulose;
(c) dispersing TEMPO oxidized bagasse cellulose or sodium periodate modified TEMPO oxidized bagasse cellulose in neutral or alkalescent aqueous solution to form suspension, and mechanically treating the suspension to obtain aqueous phase dispersion; then removing undispersed fibers and flocculated parts in the aqueous phase dispersion liquid by a centrifugation or filtration method to obtain supernatant;
(d) mixing an oily solvent and the supernatant to obtain a mixed system, and carrying out high-speed homogenization or ultrasonic dispersion on the mixed system to obtain a stable pickering emulsion; wherein the volume mixing ratio of the oily solvent and the supernatant is 1:5-2: 1.
2. The method of claim 1, wherein the bagasse cooking pretreatment is performed in a mixture of sulfurous acid and acid sulfite.
3. The method of claim 1, wherein the bleaching treatment is bleaching with chlorite or a biological laccase.
4. The method of claim 1, wherein the TEMPO oxidative modification of bagasse cellulose comprises: dispersing bagasse cellulose in a solution in which TEMPO and sodium bromide are dissolved, adding an oxidant sodium hypochlorite of 2-10mmol/g cellulose, selectively oxidizing C6 primary hydroxyl of the bagasse cellulose at 20-40 ℃, dropwise adding a sodium hydroxide solution in the oxidation process to maintain the pH of a mixed system to be stable at about 10, adding ethanol to terminate the reaction after the pH does not decrease any more, repeatedly centrifuging or filtering water-insoluble substances in the cleaning system by using distilled water, and cleaning when the conductivity of clear liquid is close to that of the distilled water, wherein the obtained water-insoluble substances are TEMPO oxidized bagasse cellulose.
5. The method according to claim 4, wherein the carboxyl content of the TEMPO oxidized bagasse cellulose is in the range of 0.5 to 1.8mmol/g cellulose.
6. The method of claim 4, wherein the TEMPO oxidation is combined with sodium periodate oxidation modified TEMPO comprising:
dispersing TEMPO oxidized bagasse cellulose in water, adding sodium periodate with the mass of 0.5-2 times that of the cellulose, carrying out selective ring-opening oxidation of hydroxyl groups at C2 and C3 under dark conditions, keeping the system constantly and uniformly stirred in the oxidation process, wherein the oxidation reaction temperature is 30-60 ℃, the reaction time is 1-24 hours, adding a small amount of glycol to terminate the reaction when the reaction is finished, then repeatedly centrifuging by using distilled water or filtering water-insoluble substances in the cleaning system, and cleaning until the conductivity of clear liquid is close to that of the distilled water, wherein the obtained water-insoluble substances are the sodium periodate modified TEMPO oxidized bagasse cellulose.
7. The method according to claim 6, wherein the sodium periodate-modified TEMPO oxidized bagasse cellulose has an aldehyde group content in the range of 0.1-2.0mmol/g cellulose.
8. The method according to claim 1, wherein the bagasse nanocellulose in the supernatant is 2-10nm in diameter and 0.2-10um in length.
9. The method according to claim 1, wherein the oily solvent comprises but is not limited to a single oil phase of liquid paraffin, toluene, castor oil, soybean oil, peanut oil, olive oil, sunflower oil, n-heptane, dodecane, methyl methacrylate, styrene, butyl acrylate, chloroform or a mixed oil phase thereof.
10. Pickering milk obtained by the method of any one of claims 1 to 9 is applied to the fields of daily cosmetics, foods, medicines and the like.
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