Regenerated nanocellulose Pickering emulsifier for liquid paraffin as well as preparation method and application of regenerated nanocellulose Pickering emulsifier

Abstract

The invention discloses a regenerated nanocellulose Pickering emulsifier for liquid paraffin as well as a preparation method and application of the regenerated nanocellulose Pickering emulsifier. According to the preparation method, ionic liquid is used as a solvent, palmitoyl chloride is used as a functional monomer, and cellulose is esterified in a homogeneous environment by utilizing the characteristic that the cellulose can be dissolved in the ionic liquid, so that functional cellulose with different substitution degrees is obtained; meanwhile, the characteristic that the nano-crystalline cellulose can be prepared by dissolving the cellulose through the ionic liquid is utilized, the functionalized nano-crystalline cellulose is obtained while the cellulose is esterified, the functionalized nano-crystalline cellulose for the Pickering emulsifier is prepared through a one-step method, the functionalized nano-crystalline cellulose is used for emulsifying liquid paraffin, and the emulsifying effect is excellent.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a recycled nanocellulose Pickering emulsifier for liquid paraffin, its preparation method, and its application. Background Technology

[0002] Liquid paraffin is mainly derived from low-carbon C10-C18 n-alkanes in petroleum fractions and is industrially used primarily as a common chemical raw material intermediate. Research has found that emulsions prepared from liquid paraffin are not only more convenient to use but also have a wider range of applications, enabling them to be used in oilfield extraction, papermaking, energy storage, environmental protection, and metal brightening agents.

[0003] Traditional paraffin oil / water emulsifiers are mostly chemically synthesized surfactants, which have drawbacks such as large dosage and the need for subsequent impurity separation. Furthermore, some synthetic surfactants pose a risk of toxic residues, limiting their application in food, cosmetics, and other fields with high safety requirements. Pickering emulsions, on the other hand, use solid particles instead of traditional organic surfactants to stabilize the emulsion system. Due to their lower emulsifier dosage, lower cost, environmental friendliness, and avoidance of the toxicity and negative effects of surfactants, they have gained widespread use in recent years.

[0004] Nanocellulose, as a natural and renewable material, possesses advantages such as good biodegradability, large specific surface area, and abundant surface active sites, making it a research hotspot in Pickering emulsifiers. However, natural nanocellulose is rich in hydroxyl groups on its surface, exhibiting strong hydrophilicity and poor compatibility with hydrophobic oily substances such as paraffin oil. When used directly as an emulsifier, it is difficult to effectively reduce the oil / water interfacial tension and thus stabilize the oil / water system. To obtain better emulsion stability and smaller particle size, it is often necessary to modify nanocellulose hydrophobically to balance its hydrophilic and oleophilic properties.

[0005] In existing technologies, the hydrophobic modification of cellulose nanoparticles with Pickering emulsifiers is basically a surface modification. This requires the preparation of cellulose nanoparticles before functionalization, which presents the following problems: (1) Firstly, the traditional method of preparing cellulose nanoparticles consumes a large amount of strong acids and bases, which are difficult to recycle and cause significant environmental pollution; (2) The process of preparing cellulose nanoparticles before functionalization is too complicated; (3) The functionalization reaction environment of cellulose nanoparticles is mainly concentrated at the solid-liquid interface, which is a heterogeneous environment. During the reaction, the mass transfer rate and temperature, the particle size and distribution of cellulose nanoparticles, and their influence on their dispersibility in the liquid phase, as well as the complexity of the microstructure of the solid-liquid interface, including surface roughness, pore structure, and the degree of reaction and grafting rate of the final product, all play a crucial role. Therefore, to obtain functionalized cellulose nanoparticles with stable performance, strict control of raw material quality and process conditions is necessary.

[0006] Therefore, developing a simple, environmentally friendly method for preparing functionalized nanocellulose for Pickering emulsifiers with undemanding reaction condition control is of great practical significance. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0008] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0009] Therefore, the object of the present invention is to overcome the shortcomings of the prior art and provide a recycled nanocellulose Pickering emulsifier for liquid paraffin.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a Pickering emulsifier for regenerated nanocellulose in liquid paraffin, characterized in that: the emulsifier is palmitoyl chloride esterified nanocellulose, and the degree of substitution of the palmitoyl chloride esterified nanocellulose is 0.05~0.7; The emulsifier is prepared by dissolving cellulose in an ionic liquid, reacting it with palmitoyl chloride via homogeneous esterification, and then regenerating it with methanol.

[0011] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of a recycled nanocellulose Pickering emulsifier for liquid paraffin in the preparation of Pickering emulsions, characterized in that: the preparation method of the Pickering emulsion includes mixing liquid paraffin, deionized water and emulsifier, and ultrasonically dispersing to obtain the Pickering emulsion.

[0012] In a preferred embodiment of the application described in this invention, the mass ratio of the liquid paraffin, deionized water, and emulsifier is 3:7:0.05.

[0013] In a preferred embodiment of the application described in this invention, the pH value of the deionized water is 4 to 12.

[0014] Another object of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing a recycled nanocellulose Pickering emulsifier for liquid paraffin, characterized in that it includes: Cellulose is heated until it is fully dissolved in an ionic liquid to obtain a cellulose ionic liquid solution; Palmitoyl chloride was added to a cellulose ionic liquid solution, heated and stirred until homogeneous, and then methanol was slowly added while maintaining constant temperature and stirring to precipitate regenerated functionalized nanocellulose. After precipitation, the solution is poured into a beaker, washed with methanol, and the resulting suspension is centrifuged and freeze-dried to obtain palmitoyl chloride-esterified regenerated nanocellulose solid powder, which is the regenerated nanocellulose Pickering emulsifier for liquid paraffin.

[0015] In a preferred embodiment of the preparation method described in this invention, the cellulose is heated to fully dissolve in an ionic liquid, wherein the heating temperature is 70-100 °C and the heating time is 18-24 h; the ionic liquid is one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, N-butylpyridinium chloride, 1-allyl-3-methylimidazolium chloride, and N,N-dimethylformamide; the cellulose is at least one of natural cellulose, regenerated cellulose, and bacterial cellulose; and the mass ratio of cellulose to ionic liquid is 1:10-100.

[0016] In a preferred embodiment of the preparation method described in this invention, palmitoyl chloride is added to the cellulose ionic liquid solution, wherein the molar ratio of palmitoyl chloride to the dehydrated glucose unit in the cellulose ionic liquid solution is 0.5 to 3:1.

[0017] In a preferred embodiment of the preparation method described in this invention, the heating and stirring are carried out at a temperature of 70–90°C and a heating time of 1–5 h.

[0018] In a preferred embodiment of the preparation method described in this invention, methanol is slowly added, wherein the amount of methanol added is 20–50 mL.

[0019] As a preferred embodiment of the preparation method described in this invention, the obtained suspension is centrifuged and freeze-dried, wherein the centrifugation speed is 5000-15000 rpm, the time is 10-15 min, and the centrifugation is repeated 3-5 times; the freeze-drying temperature is -80--60℃, and the time is 24-36 h.

[0020] Beneficial effects of this invention: (1) This invention uses ionic liquid as the solvent and homogeneous reaction medium for cellulose, and palmitoyl chloride with high reactivity as the functional monomer. By optimizing the reaction conditions such as reactant ratio, reaction temperature and reaction time, it achieves the preparation of highly substituted modified cellulose through esterification under homogeneous conditions. Then, by controlling the regeneration conditions, the functionalized cellulose is further nanoscaled.

[0021] (2) The preparation method of palmitoyl chloride esterified cellulose nanoparticles of the present invention is simple, has a short cycle, no harmful side effects, and the organic solvent can be recycled and reused, reducing production costs.

[0022] (3) The present invention uses palmitoyl chloride esterified nanocellulose as an emulsifier for paraffin oil / water Pickering emulsion, and the emulsification effect is excellent. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 The infrared spectra of the emulsifiers prepared in the examples and comparative examples are shown.

[0024] Figure 2 The images show the morphology of the emulsifiers prepared in the examples and comparative examples, where (a) is CNC and (b) is P. 2:1 CNC. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] The raw materials used in this invention are sourced from: microcrystalline cellulose (MCC): analytical grade, Sinopharm Chemical Reagent Co., Ltd.; 1-allyl-3-methylimidazolium chloride: chemically pure, Shanghai Titan Technology Co., Ltd.; palmitoyl chloride: chemically pure, Shanghai Titan Technology Co., Ltd.; anhydrous ethanol and methanol: both analytical grade, Sinopharm Chemical Reagent Co., Ltd.; liquid paraffin: analytical grade, Sinopharm Chemical Reagent Co., Ltd.

[0029] The testing methods used in the embodiments of this invention are as follows: (1) Elemental analysis: The mass fraction of carbon (%C) in the nanocellulose solid powder was analyzed using an organic elemental analyzer manufactured by Elymonte, Germany, and the degree of substitution (DS) was calculated according to the following formula: Where: 6×M C It is the relative atomic mass of carbon in a cellulose molecule. %C It refers to the carbon content of palmitoyl chloride-esterified nanocellulose, M CNC M is the relative atomic mass of a cellulose unit. g It is the mass of the grafted molecule, M Cg It is the relative atomic mass of carbon in the grafted molecule.

[0030] (2) Emulsion particle size: The average size and distribution of emulsion particles were measured using a laser particle size analyzer; the microstructure of emulsion droplets was observed using a confocal laser scanning microscope. The size and distribution of emulsion droplets were statistically analyzed using ImageJ software, and at least 50 droplets were counted.

[0031] (3) Emulsion separation index: The degree of phase separation of emulsion is described by the emulsion separation index. The emulsion separation index is usually expressed as the ratio of the height of the emulsion layer to the height of the initial emulsion.

[0032] Example 1 This embodiment provides a method for preparing a Pickering emulsifier for liquid paraffin made from regenerated nanocellulose, specifically including the following steps: (1) Add 30 g of 1-allyl-3-methylimidazolium chloride to a three-necked flask, place it in an oil bath and heat it to 85°C. After the temperature is reached, add 0.6 g of microcrystalline cellulose and stir at 200 rpm for 20 h to dissolve.

[0033] (2) Add 0.56 g of palmitoyl chloride to the dissolved cellulose ionic liquid solution, wherein the molar ratio of palmitoyl chloride to the dehydrated glucose unit of cellulose is 0.5:1. After reacting at a constant temperature for 2 h, add 15 mL of methanol to precipitate.

[0034] (3) After precipitation, pour the mixture into a beaker, add 180 mL of methanol, stir thoroughly, then pour the mixture into a centrifuge tube and centrifuge at 1000 rpm for 10 min. Centrifuge 3 times. The solid obtained by centrifugation is washed into a petri dish with 15 mL of methanol to obtain a suspension. Freeze-dry the suspension at -50℃ for 36 h to obtain palmitoyl chloride esterified regenerated nanocellulose solid powder, which is the regenerated nanocellulose Pickering emulsifier for liquid paraffin, denoted as P.0.5:1 CNC.

[0035] Example 2 The only difference between this embodiment and Example 1 is that the amount of palmitoyl chloride in step (2) is adjusted to 1.12 g. All other steps are the same as in Example 1, and palmitoyl chloride esterified nanocellulose solid powder is obtained, denoted as P. 1:1 CNC.

[0036] Example 3 The only difference between this embodiment and Example 1 is that the amount of palmitoyl chloride in step (2) is adjusted to 2.24 g. All other steps are the same as in Example 1, and palmitoyl chloride esterified nanocellulose solid powder is obtained, denoted as P. 2:1 CNC.

[0037] Example 4 The only difference between this embodiment and Example 1 is that the amount of palmitoyl chloride in step (2) is adjusted to 3.36 g. All other steps are the same as in Example 1, and palmitoyl chloride esterified nanocellulose solid powder is obtained, denoted as P. 3:1 CNC.

[0038] Comparative Example 1 The only difference between this comparative example and Example 1 is that the amount of palmitoyl chloride in step (2) is adjusted to 0g to obtain nanocellulose solid powder, denoted as CNC.

[0039] The products obtained in Examples 1-4 and Comparative Example 1 were tested, and the test results are shown in Table 1.

[0040] Table 1

[0041] Table 1 shows the elemental analysis data for Example 1 and Comparative Example 1. When the reaction time was 3 h and the reaction temperature was 80 °C, the degree of substitution increased with the increase of palmitoyl chloride dosage. This demonstrates that the degree of substitution of palmitoyl chloride-esterified nanocellulose can be adjusted by regulating the amount of palmitoyl chloride.

[0042] The CNC and P were analyzed using a Nicolet 6700 Fourier transform infrared spectrometer manufactured by Thermo Fisher Scientific. 2:1 CNC machining was used for inspection, with a resolution of 4cm. -1 Wavenumber range 3750–600 cm⁻¹ -1 ,like Figure 1 As shown.

[0043] CNC and P were observed using a field emission scanning electron microscope (S-4800 model) manufactured by Hitachi, Ltd., Japan. 2:1The morphology of CNC was determined using methanol as a solvent. The sample was diluted to 0.01% of the solvent mass, and 3 μL was dropped onto a silicon wafer. After air drying, the wafer was mounted on a scanning stage, followed by gold sputtering. The morphological characteristics were then observed and captured. The results are as follows: Figure 2 As shown, its nanoscale morphology can be observed.

[0044] Example 5 This embodiment provides a method for preparing a Pickering emulsion, including the following steps: Take 3g of liquid paraffin and 7g of deionized water, and respectively mix them with 0.04g of emulsifier (CNC, P). 0.5:1 CNC, P 1:1 CNC, P 2: 1CNC, P 3:1 The emulsions were mixed using CNC (Computer Nuclei) and named as Sample 1, Sample 2, Sample 3, Sample 4, and Sample 5. The emulsions were then ultrasonically dispersed for 3 minutes using a cell disruptor at 300W to obtain Pickering emulsions.

[0045] Table 2

[0046] Table 2 shows the emulsion particle size and emulsion separation index data of the Pickering emulsion obtained in Example 5 after 21 days.

[0047] Table 2 shows that as the degree of substitution increases, the emulsion particle size first decreases and then increases, while the emulsion separation index first increases and then decreases. This indicates that the emulsification effect first improves and then decreases with increasing degree of substitution. This is because when the degree of substitution of the emulsifier is low, there are insufficient hydrophobic groups on the surface of nanocellulose, and the proportion of hydrophilic hydroxyl groups is high, making it difficult to adsorb at the oil-water interface and reduce interfacial tension. The emulsification ability is weak, and oil-water separation easily occurs, resulting in large and uneven emulsion droplets. When the degree of substitution is moderate, the hydrophobic chains interact with the oil phase, and the hydrophilic parts combine with water, firmly anchoring at the interface to form a dense adsorption layer, preventing droplet aggregation. At this point, the effect is optimal, with small and uniform emulsion droplets, good long-term storage stability, and minimal interfacial tension. However, when the degree of substitution is too high, the overall hydrophobicity of nanocellulose increases, making it prone to self-aggregation rather than dispersion in the aqueous phase, failing to effectively play a role in interfacial stabilization, and resulting in a poorer emulsification effect. In summary, P 1:1 CNC emulsification has the best effect.

[0048] Example 6 Take 3g of liquid paraffin and 7g of deionized water, and respectively add 0.01g, 0.02g, 0.03g, 0.04g, 0.05g, 0.06g, 0.08g, and 0.10g of emulsifier (P). 1:1The mixture was prepared by CNC mixing and ultrasonic dispersion at 300W for 3 min using a cell disruptor to obtain Pickering emulsions. The resulting emulsions were named as follows: 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%.

[0049] Table 3

[0050] Table 3 shows the emulsion particle size and emulsion separation index data of the Pickering emulsion obtained in Example 6 after 21 days. As shown in Table 3, the droplet size changes in the emulsion exhibit two different patterns: at low dosages, the droplet size continuously decreases with increasing dosage. This is because insufficient dosage leads to inadequate interfacial adsorption, failing to completely encapsulate the oil droplets, causing them to easily collide and aggregate. Higher dosages cover a larger interfacial area, resulting in smaller droplet sizes and higher stability. At a dosage of 0.5 wt%, the droplet size remains almost constant under the limitation of emulsification efficiency, not changing with further increases in dosage. Smaller droplet sizes, lower density differences between the oil and water phases, and higher suspension viscosity all slow down phase separation in the emulsion, thereby improving emulsion stability and resulting in a higher emulsion separation index. The emulsion separation index is positively correlated with the amount of emulsifier used; the higher the dosage, the more stable the resulting emulsion.

[0051] Example 7 Add 0.05g of emulsifier (P) 1:1 (CNC) was added to solutions with oil-to-water ratios of 1:9, 2:8, 3:7, 4:6, 5:5, and 6:4, with a total mass of 10g. Pickering emulsions were prepared by ultrasonic dispersion for 3 minutes using a cell disruptor at 300W. The resulting emulsions were named 1:9, 2:8, 3:7, 4:6, 5:5, and 6:4.

[0052] Table 4

[0053] Table 4 shows the emulsion particle size and emulsion separation index data of the Pickering emulsion obtained in Example 7 after 21 days. As can be seen from Table 4, changes in the ratio of oil phase to water phase significantly affect the P... 1:1 CNC stabilizes the droplet size distribution of emulsions.

[0054] Specifically, as the oil-to-water ratio changes, the average diameter of the emulsion droplets shows a significant changing trend, and the stability of the system also changes significantly. This phenomenon indicates that the oil-to-water ratio is a regulator of P. 1:1 One of the key parameters for CNC-stabilized Pickering emulsion performance is... 1:1At a CNC concentration of 0.5 wt%, the average droplet diameters of the emulsions with low oil-to-water ratios (1:9) and high oil-to-water ratios (6:4) were 785 nm and 8 μm, respectively. This indicates that the sample with a high oil-to-water ratio had a larger particle size compared to the low oil-to-water ratio. This is because, under the condition of constant emulsifier dosage, increasing the oil phase content leads to a decrease in interfacial coverage. This insufficient interfacial coverage induces droplet aggregation. As the droplet size increases, the aggregation process accelerates significantly, resulting in smaller droplets agglomerating more rapidly. When the oil-to-water ratio increases to 6:4, the emulsion becomes unstable, and the reaction cannot completely stabilize the emulsion at this point. Observing the emulsions at different oil-to-water ratios after 21 days of storage, the emulsion separation index was the lowest at an oil-to-water ratio of 5:5.

[0055] Overall, palmitoyl chloride esterified P 1:1 CNC has good hydrophilicity and oleophilicity, and its stability is best when the oil-water ratio is 1:9.

[0056] Example 8 Add 0.05g of emulsifier (P) 1:1 (CNC), 3g of liquid paraffin and 7g of deionized water were mixed, and the pH values ​​of the deionized water were controlled to be 2, 4, 6, 8, 10 and 12 respectively. After mixing, the mixture was ultrasonically dispersed at 300W for 3 min using a cell disruptor to prepare Pickering emulsions. The resulting emulsions were named pH2, pH4, pH6, pH8, pH10 and pH12.

[0057] Table 5

[0058] Table 5 shows the emulsion droplet size and emulsion separation index data of the Pickering emulsion obtained in Example 8 after 21 days. As shown in Table 5, when the system pH is within the range of 4–8, the emulsion droplet size remains stable, indicating that the emulsion has good anti-agglomeration properties within this pH range.

[0059] However, when the pH value was further decreased, significant droplet aggregation was observed, characterized by a significant increase in average particle size and a decrease in system stability. Mechanistic analysis revealed that this phenomenon mainly stemmed from: 1) H... + Adsorption on the particle surface leads to surface charge neutralization, significantly weakening the electrostatic repulsion between particles; 2) Protonation alters the surface properties of nanocellulose, thus affecting its emulsifying properties. Increasing the pH value significantly reduces the droplet size of the emulsion and enhances its stability, indicating that the emulsion has strong alkali resistance.

[0060] Observations after 21 days of emulsion storage showed that the pH ranged from 4 to 12, and the P... 1:1 CNC can effectively stabilize Pickering emulsions.

[0061] Example 9 0.05 g of emulsifier (P1:1CNC), 3 g of liquid paraffin and 7 g of deionized water were mixed, and the salt concentrations were controlled to be 0, 20, 40, 60, 80, 100 and 200 mM, respectively. After mixing, the mixture was ultrasonically dispersed at 300 W for 3 min using a cell disruptor to prepare Pickering emulsions. The resulting emulsions were named 0, 20, 40, 60, 80, 100 and 200.

[0062] Table 6

[0063] Table 6 shows the emulsion particle size and emulsion separation index data of the Pickering emulsion obtained in Example 9 after 21 days. As can be seen from Table 6, the size and polydispersity of the emulsion droplets are basically unaffected by the salt concentration, reflecting the characteristics of P... 1:1 CNC-stabilized Pickering emulsions exhibit anti-agglomeration stability at high salt concentrations.

[0064] As the salt concentration in the system increases, the emulsion exudation index of the emulsion also increases, indicating that the addition of sodium chloride promotes the precipitation of P. 1:1 The adsorption of CNC at the oil-water interface is beneficial to the stability of Pickering emulsions, indicating that P 1:1 CNC-stabilized Pickering emulsions exhibit excellent salt resistance.

[0065] The emulsifier process of this invention is simple, environmentally friendly, and does not require stringent control of reaction conditions. First, cellulose is heated and fully dissolved in an ionic liquid to obtain a cellulose ionic liquid solution. Palmitoyl chloride is added to the cellulose ionic liquid solution according to a specific molar ratio of palmitoyl chloride to the dehydrated glucose units of cellulose, and the mixture is thoroughly mixed and heated to react. Subsequently, while maintaining a constant temperature and stirring, methanol is slowly added to precipitate regenerated functionalized nanocellulose. After precipitation, the solution is poured into a beaker, washed with methanol, and the resulting suspension is centrifuged and freeze-dried to obtain palmitoyl chloride-esterified regenerated nanocellulose solid powder.

[0066] This invention uses ionic liquids as solvents and palmitoyl chloride as a functional monomer. Taking advantage of the fact that cellulose can dissolve in ionic liquids, cellulose is esterified in a homogeneous environment to obtain functionalized cellulose with different degrees of substitution. At the same time, taking advantage of the fact that ionic liquids can dissolve cellulose to prepare nanocellulose, functionalized nanocellulose is obtained while esterifying cellulose. Functionalized nanocellulose for Pickering emulsifiers is prepared in one step and used for emulsification of liquid paraffin.

[0067] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A regenerated nanocellulose Pickering emulsifier for liquid paraffin, characterized by: The emulsifier is palmitoyl chloride esterified nanocellulose, and the degree of substitution of the palmitoyl chloride esterified nanocellulose is 0.05-0.7; The emulsifier is prepared by dissolving cellulose in an ionic liquid, carrying out a homogeneous esterification reaction with palmitoyl chloride, and then regenerating through methanol.

2. Use of the regenerated nanocellulose Pickering emulsifier for liquid paraffin according to claim 1 for the preparation of Pickering emulsions, characterized in that: The preparation method of the Pickering emulsion comprises mixing liquid paraffin, deionized water and the emulsifier, and ultrasonic dispersion to obtain the Pickering emulsion.

3. Use according to claim 2, wherein: The mass ratio of the liquid paraffin, the deionized water and the emulsifier is 3:7:0.

05.

4. The use according to claim 2, characterized in that: The pH value of the deionized water is 4-12.

5. The method for preparing regenerated nanocellulose Pickering emulsifier for liquid paraffin according to claim 1, characterized in that: The preparation method comprises the following steps: The cellulose is heated and sufficiently dissolved in an ionic liquid to obtain a cellulose ionic liquid solution; Palmitoyl chloride is added to the cellulose ionic liquid solution, and heated and stirred uniformly, and then methanol is slowly added to precipitate regenerated functionalized nanocellulose while the temperature and stirring are kept unchanged; After precipitation, the obtained suspension is poured into a beaker, washed with methanol, centrifuged, and freeze-dried to obtain a palmitoyl chloride esterified regenerated nanocellulose solid powder, which is the Pickering emulsifier for liquid paraffin.

6. The production method according to claim 5, characterized by: The cellulose is heated and sufficiently dissolved in an ionic liquid, wherein the heating temperature is 70-100 ℃, and the heating time is 18-24 h; the ionic liquid is one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, N-butylpyridinium chloride, 1-allyl-3-methylimidazolium chloride and N,N-dimethylformamide; the cellulose is at least one of natural cellulose, regenerated cellulose and bacterial cellulose; and the mass ratio of the cellulose to the ionic liquid is 1:10-100.

7. The production method according to claim 5, wherein: The palmitoyl chloride is added to the cellulose ionic liquid solution, and the molar ratio of the palmitoyl chloride to the anhydroglucose units in the cellulose ionic liquid solution is 0.5-3:

1.

8. The production method according to claim 5, wherein: The heating and stirring are uniform, and the heating temperature is 70-90 ℃, and the heating time is 1-5 h.

9. The production method according to claim 5, wherein: The methanol is slowly added, and the amount of the added methanol is 20-50 mL.

10. The production method according to claim 5, wherein: The obtained suspension is centrifuged and freeze-dried, wherein the centrifugation is performed at a speed of 5000-15000 rpm for 10-15 min, and the centrifugation is performed for 3-5 times; the freeze-drying is performed at a temperature of-80--60 ℃ for 24-36 h.

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