A method for eluting white oil or decalin from high molecular weight polyethylene materials by means of an ionic liquid system

Abstract

The present application belongs to the field of chemical production, and relates to a method for washing white oil or decalin in high molecular weight polyethylene material through an ionic liquid system. An ionic liquid is mixed with water to obtain an ionic liquid washing solution; the polyethylene gel filament is placed in the ionic liquid washing solution for washing, and the white oil or decalin adhered to the gel filament is cleaned; after the cleaning is completed, solid-liquid separation is performed, and the ionic liquid washing solution on the surface of the gel filament is cleaned, so that the high molecular weight polyethylene material from which the white oil or decalin is removed is obtained. For the ionic liquid which is solid at room temperature, the water solution thereof can be used to realize the washing of the decalin and white oil adhered to the gel filament, thereby widening the range of ionic liquids which can be used to wash the decalin or white oil adhered to the gel filament at room temperature. The present application uses the water solution of the ionic liquid to replace the pure ionic liquid for washing, improves the mass of the decalin or white oil washed per unit mass of the ionic liquid, and thus can reduce the amount of the ionic liquid, and is economic and green.

Description

Technical Field

[0001] This invention belongs to the field of chemical production and relates to a method for eluting white oil or decahydronaphthalene from high molecular weight polyethylene materials using an ionic liquid system. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMWPE) is a high-performance material developed since the 1980s. Over the past 20 years, its production technology has been continuously improved, resulting in significant advancements in both performance and yield. It has already played a crucial role in navigation, aviation, aerospace, defense equipment, and modern warfare. Currently, UHMWPE production methods include melt processing, high-pressure extrusion, surface growth crystallization, flash evaporation, and gel molding. Among these, gel molding is the most commercially successful method.

[0003] The gel molding method uses polyethylene as raw material and kerosene, white oil, or decahydronaphthalene as solvent. These are mixed in a specific ratio to form a dilute solution, which is then added to a twin-screw extruder for high-temperature swelling and dissolution. The mixture is then molded in a mold, and the white oil or decahydronaphthalene is extracted using a second solvent. The white oil or decahydronaphthalene is then separated from the second solvent and recycled. Common second solvents include hydrocarbons, gasoline, xylene, dichloromethane, and acetone. In practical industrial applications, hydrocarbons are the primary solvent. Hydrocarbons have properties similar to gasoline and pose VOC (volatile organic compounds) problems. Furthermore, the production process requires a high-temperature environment, resulting in extremely high safety risks.

[0004] In addition, in traditional extraction processes, the extractants such as hydrocarbons, tetrachloroethylene, and dichloromethane have a high solubility for white oil and decahydronaphthalene, resulting in a very fast extraction speed. After the white oil or decahydronaphthalene on the surface of the gel is quickly extracted, a dense skin structure is formed, making it difficult to extract the white oil or decahydronaphthalene inside the gel. At the same time, polyethylene materials cannot achieve a high degree of uniformity in microstructure, which easily leads to problems such as high fiber hardness and roughness.

[0005] Ionic liquids are ionic compounds composed of anions and cations, possessing excellent thermal stability, electrical conductivity, and plasticity. Furthermore, ionic liquids offer advantages such as being odorless, non-toxic, non-polluting, non-flammable, easily separated from products, easily recyclable, reusable multiple times, and convenient to use. As a green solvent, it avoids the serious environmental, health, safety, and equipment corrosion problems caused by traditional organic solvents. Ionic liquids are molten salts with extremely low volatility, thus eliminating VOCs issues. Their near-non-volatile nature not only solves the VOCs problem but also reduces losses associated with traditional extractants. However, ionic liquids are relatively expensive, and reducing the amount used to decrease costs while efficiently washing away adhering white oil or decahydronaphthalene from gel filaments remains a challenge. Summary of the Invention

[0006] The technical problem to be solved by the invention is to address the VOCs problem in the production of ultra-high molecular weight polyethylene (UHMWPE) materials using the gel technology route in the prior art and to reduce production costs. The invention provides a method for eluting white oil or decahydronaphthalene from UHMWPE materials using an ionic liquid system. The method provided in this application is simple to operate, has a high oil removal rate, and is economical.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] This invention discloses a method for eluting white oil or decahydronaphthalene from high molecular weight polyethylene material using an ionic liquid system. The method involves mixing an ionic liquid with water to obtain an ionic liquid washing solution; placing polyethylene gel fibers in the ionic liquid washing solution for washing to remove the white oil or decahydronaphthalene adhering to the gel fibers; after washing, solid-liquid separation is performed, and the ionic liquid washing solution is used to clean the surface of the gel fibers to obtain high molecular weight polyethylene material free of white oil or decahydronaphthalene.

[0009] In this process, when white oil is used as a solvent during the preparation of the polyethylene gel fiber, the high molecular weight polyethylene material with the white oil removed is obtained after ultrasonic washing with an ionic liquid washing solution.

[0010] In this process, when the polyethylene gel fiber is prepared using decahydronaphthalene as a solvent, it is ultrasonically washed with an ionic liquid washing solution to obtain a high molecular weight polyethylene material with decahydronaphthalene removed.

[0011] The polyethylene gel filament can be made from polyethylene products such as polyethylene fiber, polyethylene film, and polyethylene gel; the weight-average molecular weight of the polyethylene gel filament is preferably 100w to 600w, more preferably 300w to 600w, even more preferably 400w to 600w, and most preferably 500w.

[0012] In some embodiments, the cation of the ionic liquid is an imidazole cation, a pyridine cation, a quaternary ammonium cation, a pyrrolidine cation, a piperidine cation, a quaternary phosphorus cation, a guanidine cation, a morpholine cation, a thiazole cation, or a pyrazole cation.

[0013] In some embodiments, the cationic group of the ionic liquid contains 1 to 2 C3 to C18 alkyl groups; the C3 to C18 alkyl groups are straight-chain or branched.

[0014] In some embodiments, preferably, the C3 to C18 alkyl groups are selected from C3 alkyl, C4 alkyl, C6 alkyl, C8 alkyl, C10 alkyl, C12 alkyl, C16 alkyl, or C18 alkyl.

[0015] In some embodiments, the anion of the ionic liquid is a halide anion, carboxyl anion, nitrate anion, sulfate anion, hydrogen sulfate anion, tetrafluoroborate anion, hexafluorophosphate anion, sulfonic acid anion, thiocyanate anion, or phosphate ester anion.

[0016] In some embodiments, preferably, the ionic liquid is 1-hexadecane-3-methylimidazolium chloride, 1-dodecane-3-methylimidazolium chloride, hexadecyltrimethylammonium bromide, 1-hexadecane-3-methylimidazolium acetate, tetrabutylammonium nitrate, tetrabutyldodecylammonium sulfate, 1-hexylpyridine tetrafluoroborate, 1-butyl-1-methylpyrrolidine bromide, N-butyl-N-methylpiperidine bromide, tetrabutylhexafluorophosphate, 1-butyl-3-methylimidazolium methanesulfonate, tert-butylguanidine hydrochloride, bromide-N-methylbutylmorpholine, 1-butyl-3-methylimidazolium thiocyanate, 1-butyl-3-methylimidazolium phosphate. Dibutyl ester salt, 5-phenylthiazolium-2,4-diamine hydrobromide, 4-amino-1-isopropylpyrazole hydrochloride, 1-octyl-3-methylimidazolium chloride, 1-decane-3-methylimidazolium chloride, 1-octadecane-3-methylimidazolium chloride, hexadecyltrimethylammonium hydrogen sulfate, cetylpyridine chloride, 1-hexadecyl-1-methylpyrrolidine chloride, 1-hexadecyl-2,6-dimethylpiperidine chloride, trihexyl(tetradecyl)phosphine chloride, 2-hexadecyl-1,1,3,3-tetramethylguanidine chloride, N-hexadecyl-N-methylmorpholine chloride, 1-hexadecylthiazolium chloride, or 1-hexadecyl-3-methylpyrazole chloride.

[0017] In some embodiments, and more preferably, the ionic liquid is 1-hexadecane-3-methylimidazolium chloride, 1-dodecane-3-methylimidazolium chloride, hexadecyltrimethylammonium bromide, 1-hexadecane-3-methylimidazolium acetate, 1-octadecane-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium thiocyanate, N-methylbutylmorpholine bromide, 1-butyl-3-methylimidazolium methanesulfonate, tert-butylguanidine hydrochloride, 1-hexylpyridine tetrafluoroborate, tetrabutylhexafluorophosphate, 1-butyl-3-methylimidazolium dibutyl phosphate, or 5-phenylthiazolium-2,4-diamine hydrogen. Bromate, 4-amino-1-isopropylpyrazole hydrochloride, tetrabutylammonium nitrate, N-butyl-N-methylpiperidine bromide, 1-butyl-1-methylpyrrolidine bromide, 1-decane-3-methylimidazolium chloride, hexadecyltrimethylammonium bisulfate, cetylpyridine chloride, 1-hexadecyl-1-methylpyrrolidine chloride, 1-hexadecyl-2,6-dimethylpiperidine chloride, trihexyl(tetradecyl)phosphine chloride, 2-hexadecyl-1,1,3,3-tetramethylguanidine chloride, N-hexadecyl-N-methylmorpholine chloride, 1-hexadecylthiazolium chloride, or 1-hexadecyl-3-methylpyrazole chloride.

[0018] In some embodiments, the mass ratio of the ionic liquid to water is (0.8–12):30.

[0019] In some embodiments, the mass-to-volume ratio of the polyethylene gel fiber to the ionic liquid washing solution is 0.15–0.35 g: 1.0–3.0 mL.

[0020] In some embodiments, the polyethylene gel fibers are washed in an ionic liquid washing solution by ultrasonic washing or high-temperature stirring washing; the ultrasonic washing is performed at an ultrasonic temperature of 40°C to 60°C, with an ultrasonic power of 490 to 500W and an ultrasonic time of 0.5h to 10h; the high-temperature stirring washing is performed at a washing temperature of 80 to 130°C and a washing time of 4 to 6h.

[0021] In some embodiments, preferably, the ultrasonic power is 495W.

[0022] During the high-temperature stirring and washing process, there are no special restrictions on the stirring rate; conventional stirring is used.

[0023] In some embodiments, water is used for cleaning during the process of washing the surface of the gel fiber with an ionic liquid detergent.

[0024] Beneficial effects:

[0025] (1) For ionic liquids that are solid at room temperature, their aqueous solutions can be used to wash decahydronaphthalene and white oil adhering to gel fibers, thus broadening the range of ionic liquids that can be used to wash decahydronaphthalene or white oil adhering to gel fibers at room temperature.

[0026] (2) This invention uses an aqueous solution of ionic liquid to replace pure ionic liquid for washing, which improves the quality of washing decahydronaphthalene or white oil per unit mass of ionic liquid, thereby reducing the amount of ionic liquid used, making it economical and green. Attached Figure Description

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0028] Figure 1 This is a photograph of the polyethylene gel filament (gel filament) used in the embodiments of the present invention.

[0029] Figure 2 These are experimental comparison diagrams showing the polyethylene gel fibers used in this embodiment of the invention before and after washing; wherein, Figure 2 A is an experimental diagram of the gelled fibers before washing. Figure 2 B is an experimental diagram showing the gelatin threads after washing. Detailed Implementation

[0030] The present invention is illustrated by the following embodiments, but the present invention is not limited to the following embodiments. Any variations are included within the technical scope of the present invention without departing from the spirit described above.

[0031] The polyethylene gel fiber used in this invention experiment was manufactured by Dongguan Shengxin Special Rope & Belt Co., Ltd., with a molecular weight of 500w. Figure 1 This is a photograph of the polyethylene gel fiber (hereinafter referred to as gel fiber) used in the embodiments of the present invention; Figure 2 These are experimental comparison diagrams showing the polyethylene gel fibers used in this embodiment of the invention before and after washing; wherein, Figure 2 A is an experimental diagram of the gelled fibers before washing. Figure 2 B is an experimental diagram showing the gelatin threads after washing.

[0032] The efficiency of the ionic liquid washing solution in removing white oil or decahydronaphthalene per unit mass of ionic liquid is calculated according to the following formula:

[0033] The efficiency of removing white oil or decahydronaphthalene by unit mass of ionic liquid = (mass of white oil or decahydronaphthalene in the original gel fiber - mass of residual white oil or decahydronaphthalene in the gel fiber after washing with ionic liquid) / mass of ionic liquid in the washing liquid.

[0034] Example 1

[0035] 1.2 g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 40 °C for 3 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.01.

[0036] Example 2

[0037] 1.2 g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 3 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.07.

[0038] Example 3

[0039] 1.2 g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 60 °C for 3 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.28.

[0040] Example 4

[0041] 1.2 g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution, then sonicated at 50 °C for 60 min at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.76.

[0042] Example 5

[0043] 1.6 g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution, then sonicated at 50 °C for 60 min at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.85.

[0044] Example 6

[0045] 3g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3g of gel fiber (white oil) was weighed and added to 3mL of the ionic liquid washing solution, then sonicated at 50℃ for 60min at a power of 495W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.47.

[0046] Example 7

[0047] 6 g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution, then sonicated at 50 °C for 60 min at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.21.

[0048] Example 8

[0049] 3g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3g of gel fiber (white oil) was weighed and added to 3mL of the ionic liquid washing solution. The solution was then sonicated at 50℃ for 2 hours at a power of 495W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.58g.

[0050] Example 9

[0051] 3g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3g of gel fiber (white oil) was weighed and added to 3mL of the ionic liquid washing solution. The solution was then sonicated at 50℃ for 3 hours at a power of 495W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.58g.

[0052] Example 10

[0053] 3g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3g of gel fiber (white oil) was weighed and added to 3mL of the ionic liquid washing solution. The solution was then sonicated at 50℃ for 4 hours at a power of 495W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.60.

[0054] Example 11

[0055] 3g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3g of gel fiber (white oil) was weighed and added to 3mL of the ionic liquid washing solution. The solution was then sonicated at 50℃ for 6 hours at a power of 495W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.63.

[0056] Example 12

[0057] 3g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3g of gel fiber (white oil) was weighed and added to 3mL of the ionic liquid washing solution. The solution was then sonicated at 50℃ for 10h at a power of 495W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.70.

[0058] Example 13

[0059] 3g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3g of gel fiber (white oil) was weighed and added to 3mL of the ionic liquid washing solution. The solution was then sonicated at 50℃ for 30min at a power of 495W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.40.

[0060] Example 14

[0061] 1.2 g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 1 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.76.

[0062] Example 15

[0063] 1.2 g of 1-hexadecane-3-methylimidazolium chloride was dissolved in 30 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 4 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.16.

[0064] Example 16

[0065] 3g of 1-dodecane-3-methylimidazolium chloride was dissolved in 30mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3g of gel fiber (white oil) was weighed and added to 3mL of the ionic liquid washing solution. The solution was then sonicated at 50℃ for 5 hours at a power of 495W. After sonication, the washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.30.

[0066] Example 17

[0067] 1.3 g of hexadecyltrimethylammonium bromide was dissolved in 30 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 6 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.33.

[0068] Example 18

[0069] 3g of 1-hexadecane-3-methylimidazolium acetate was dissolved in 30mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3g of gel fiber (white oil) was weighed and added to 3mL of the ionic liquid washing solution. The solution was then sonicated at 50℃ for 5 hours at a power of 495W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.56.

[0070] Example 19

[0071] 0.6 g of tetrabutylammonium nitrate was dissolved in 10 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.17.

[0072] Example 20

[0073] 0.6 g of hexadecyltrimethylammonium bisulfate was dissolved in 10 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.94.

[0074] Example 21

[0075] 0.5 g of tetrabutyldodecyl sulfate was dissolved in 5 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 10 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.20.

[0076] Example 22

[0077] 0.6 g of cetylpyridinium chloride was dissolved in 10 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.85.

[0078] Example 23

[0079] 0.6 g of 1-hexadecyl-1-methylpyrrolidine chloride was dissolved in 10 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.74.

[0080] Example 24

[0081] 0.6 g of 1-hexadecyl-2,6-dimethylpiperidine chloride was dissolved in 10 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.31.

[0082] Example 25

[0083] 0.6 g of trihexyl(tetradecyl)phosphine chloride was dissolved in 10 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.42.

[0084] Example 26

[0085] 0.6 g of 1-butyl-3-methylimidazolium methanesulfonate was dissolved in 10 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.28.

[0086] Example 27

[0087] 0.6 g of 2-hexadecyl-1,1,3,3-tetramethylguanidine chloride was dissolved in 10 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fibers (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fibers were then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.50.

[0088] Example 28

[0089] 0.6 g of N-hexadecyl-N-methylmorpholine chloride was dissolved in 10 mL of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 mL of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.38.

[0090] Example 29

[0091] 0.6 g of 1-butyl-3-methylimidazolium thiocyanate was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 ml of the ionic liquid washing solution. The solution was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.29 g.

[0092] Example 30

[0093] 0.6 g of 1-butyl-3-methylimidazolium dibutyl phosphate salt was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and 3 ml of the ionic liquid washing solution was added. The solution was then sonicated at 50℃ for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.24.

[0094] Example 31

[0095] 0.3 g of 1-hexadecylthiazolium chloride was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fibers (white oil) was weighed and added to 3 ml of the ionic liquid washing solution. The solution was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fibers were then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.93.

[0096] Example 32

[0097] 0.6 g of 1-hexadecyl-3-methylpyrazole chloride was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3 ml of the ionic liquid washing solution. The solution was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.24.

[0098] Example 33

[0099] 0.6 g of 1-butyl-3-methylimidazolium thiocyanate was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.2043 g of gel fiber (decahydronaphthalene) was weighed and added to 2 ml of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.33.

[0100] Example 34

[0101] 0.6 g of N-methylbutylmorpholine bromide was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.2307 g of gel fiber (decahydronaphthalene) was weighed and added to 2.3 ml of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.31.

[0102] Example 35

[0103] 0.6 g of 1-butyl-3-methylimidazolium methanesulfonate was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3025 g of gel fiber (decahydronaphthalene) was weighed and added to 3.0 ml of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.28.

[0104] Example 36

[0105] 0.6 g of tert-butylguanidine hydrochloride was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.2256 g of gel fiber (decahydronaphthalene) was weighed and added to 2.3 ml of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.23.

[0106] Example 37

[0107] 0.6 g of 1-hexylpyridine tetrafluoroborate was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.2037 g of gel filament (decahydronaphthalene) was weighed and added to 2.0 ml of the ionic liquid washing solution. The mixture was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 min. The gel filament was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.30.

[0108] Example 38

[0109] 0.6 g of tetrabutylhexafluorophosphate was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.1872 g of gel fiber (decahydronaphthalene) was weighed and added to 1.8 ml of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.34.

[0110] Example 39

[0111] 0.6 g of 1-butyl-3-methylimidazolium dibutyl phosphate salt was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.1915 g of gel fiber (decahydronaphthalene) was weighed and added to 1.9 ml of the ionic liquid washing solution. The solution was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.31.

[0112] Example 40

[0113] 0.6 g of 5-phenylthiazol-2,4-diamine hydrobromide was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.2210 g of gel fiber (decahydronaphthalene) was weighed and added to 2.2 ml of the ionic liquid washing solution. The mixture was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.25.

[0114] Example 41

[0115] 0.6 g of 4-amino-1-isopropylpyrazole hydrochloride was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.2148 g of gel fiber (decahydronaphthalene) was weighed and added to 2.1 ml of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.38.

[0116] Example 42

[0117] 0.6 g of tetrabutylammonium nitrate was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.2550 g of gel fiber (decahydronaphthalene) was weighed and added to 2.5 ml of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.24.

[0118] Example 43

[0119] 0.6 g of N-butyl-N-methylpiperidine bromide was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.2501 g of gel filament (decahydronaphthalene) was weighed and added to 2.5 ml of the ionic liquid washing solution. The mixture was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 min. The gel filament was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.21.

[0120] Example 44

[0121] 0.6 g of 1-butyl-1-methylpyrrolidine bromide salt was dissolved in 10 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.1955 g of gel fiber (decahydronaphthalene) was weighed and added to 2.0 ml of the ionic liquid washing solution. The mixture was then sonicated at 50 °C for 5 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.21.

[0122] Example 45

[0123] 0.5 g of 1-dodecane-3-methylimidazolium chloride was dissolved in 5 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fibers (decahydronaphthalene) was weighed and added to 3.0 ml of the ionic liquid washing solution. The solution was then sonicated at 50 °C for 10 h at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 min. The gel fibers were then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.30.

[0124] Example 46

[0125] 0.5 g of 1-octyl-3-methylimidazolium chloride was dissolved in 5 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fibers (decahydronaphthalene) was weighed and added to 3.0 ml of the ionic liquid washing solution. The solution was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fibers were then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.13.

[0126] Example 47

[0127] 0.5 g of 1-decane-3-methylimidazolium chloride was dissolved in 5 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (decahydronaphthalene) was weighed and added to 3.0 ml of the ionic liquid washing solution. The solution was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.19 g.

[0128] Example 48

[0129] 3.0 g of 1-octadecane-3-methylimidazolium chloride was dissolved in 30 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 3.0 ml of the ionic liquid washing solution. The solution was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.57.

[0130] Example 49

[0131] 1.8 g of 1-hexadecane-3-methylimidazolium acetate was dissolved in 30 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.6 g of gel fibers (white oil) was weighed and added to 6.0 ml of the ionic liquid washing solution. The mixture was then stirred at 120 °C for 5 h for washing. After washing, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 min. The gel fibers were then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 1.03.

[0132] Example 50

[0133] 9g of 1-hexadecane-3-methylimidazolium acetate was dissolved in 30ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.6g of gel fiber (white oil) was weighed and added to 6.0ml of the ionic liquid washing solution. The solution was then sonicated at 50℃ for 5 hours at a power of 495W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.10.

[0134] Example 51

[0135] 1 g of 1-decane-3-methylimidazolium chloride was dissolved in 3 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 1 ml of the ionic liquid washing solution. The solution was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.15.

[0136] Comparative Example 1

[0137] Weigh 0.3g of gel fiber (white oil), add 1mL of 1-decane-3-methylimidazolium chloride, mix, and sonicate at 50℃ for 5h with an ultrasonic power of 495W. After sonication, remove the ionic liquid, add deionized water, sonicate at room temperature for 30min, then remove the gel fiber, dry it, and weigh it. The calculated oil removal amount per unit mass of ionic liquid is 0.06.

[0138] Example 52

[0139] 1 g of 1-octyl-3-methylimidazolium chloride was dissolved in 3 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 1 ml of the ionic liquid washing solution. The solution was then sonicated at 50°C for 5 hours at a power of 495 W. After sonication, the ionic liquid washing solution was removed, deionized water was added, and the solution was sonicated at room temperature for 30 minutes. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.10.

[0140] Comparative Example 2

[0141] Weigh 0.3g of gel fiber (white oil), add 1mL of 1-octyl-3-methylimidazolium chloride, mix, and sonicate at 50℃ for 5h with a sonication power of 495W. After sonication, remove the ionic liquid, add deionized water, sonicate at room temperature for 30min, then remove the gel fiber, dry it, and weigh it. The calculated oil removal amount per unit mass of ionic liquid is 0.05.

[0142] Example 53

[0143] 2 g of 1-decane-3-methylimidazolium chloride was dissolved in 6 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fiber (white oil) was weighed and added to 2 ml of the ionic liquid washing solution. The mixture was then stirred at 130℃ for 5 h for washing. After washing, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 min. The gel fiber was then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.10.

[0144] Comparative Example 3

[0145] Weigh 0.3g of gel fiber (white oil), add 2mL of 1-decane-3-methylimidazolium chloride, mix, and wash at 130℃ for 5h. After washing, remove the ionic liquid, add deionized water, sonicate at room temperature for 30min, then remove the gel fiber, dry, and weigh. The calculated amount of oil removed per unit mass of ionic liquid is 0.03.

[0146] Example 54

[0147] 1 g of 1-decane-3-methylimidazolium chloride was dissolved in 3 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fibers (decahydronaphthalene) was weighed and added to 1 ml of the ionic liquid washing solution. The mixture was then stirred at 80 °C for 5 h for washing. After washing, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 min. The gel fibers were then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.78.

[0148] Comparative Example 4

[0149] Weigh 0.3g of gel filament (decahydronaphthalene), add 1mL of 1-decane-3-methylimidazolium chloride, mix, and wash at 80℃ for 5h. After washing, remove the ionic liquid, add deionized water, sonicate at room temperature for 30min, then remove the gel filament, dry, and weigh. The calculated oil removal amount per unit mass of ionic liquid is 0.20.

[0150] Example 55

[0151] 1 g of 1-hexadecane-3-methylimidazolium acetate was dissolved in 4 ml of deionized water and sonicated at room temperature to obtain an ionic liquid washing solution. 0.3 g of gel fibers (white oil) was weighed and added to 1 ml of the ionic liquid washing solution. The mixture was then stirred at 120°C for 5 hours for washing. After washing, the ionic liquid washing solution was removed, deionized water was added, and the mixture was sonicated at room temperature for 30 minutes. The gel fibers were then removed, dried, and weighed. The calculated oil removal amount per unit mass of ionic liquid was 0.57.

[0152] Comparative Example 5

[0153] Weigh 0.3g of gel fiber (white oil), add 1mL of 1-hexadecane-3-methylimidazolium acetate, mix, and wash by stirring at 120℃ for 5h. After washing, remove the ionic liquid, add deionized water, sonicate at room temperature for 30min, then remove the gel fiber, dry, and weigh. The calculated amount of oil removed per unit mass of ionic liquid is 0.17.

[0154] This invention provides a method for eluting white oil or decahydronaphthalene from high molecular weight polyethylene materials using an ionic liquid system. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for eluting white oil or decahydronaphthalene from high molecular weight polyethylene material using an ionic liquid system, characterized in that, The ionic liquid is mixed with water to obtain an ionic liquid washing solution. The polyethylene gel fibers are placed in the ionic liquid washing solution for washing to remove the white oil or decahydronaphthalene adhering to the gel fibers. After washing, the solid and liquid are separated, and the ionic liquid washing solution is used to clean the surface of the gel fibers to obtain high molecular weight polyethylene material with the white oil or decahydronaphthalene removed.

2. The method according to claim 1, characterized in that, The cation of the ionic liquid is an imidazole cation, a pyridine cation, a quaternary ammonium cation, a pyrrolidine cation, a piperidine cation, a quaternary phosphorus cation, a guanidine cation, a morpholine cation, a thiazole cation, or a pyrazole cation.

3. The method according to claim 2, characterized in that, The ionic liquid contains 1 to 2 C3 to C18 alkyl groups in its cationic groups; the C3 to C18 alkyl groups are either straight-chain or branched.

4. The method according to claim 3, characterized in that, The C3~C18 alkyl group is selected from C3 alkyl, C4 alkyl, C6 alkyl, C8 alkyl, C10 alkyl, C12 alkyl, C16 alkyl or C18 alkyl.

5. The method according to claim 1, characterized in that, The anions of the ionic liquid are halide anions, carboxyl anions, nitrate anions, sulfate anions, hydrogen sulfate anions, tetrafluoroborate anions, hexafluorophosphate anions, sulfonic acid anions, thiocyanate anions, or phosphate ester anions.

6. The method according to claim 1, characterized in that, The ionic liquid is 1-hexadecane-3-methylimidazolium chloride, 1-dodecane-3-methylimidazolium chloride, hexadecyltrimethylammonium bromide, 1-hexadecane-3-methylimidazolium acetate, tetrabutyldodecylammonium sulfate, 1-hexylpyridine tetrafluoroborate, 1-butyl-1-methylpyrrolidine bromide, N-butyl-N-methylpiperidine bromide, tetrabutylhexafluorophosphate, 1-butyl-3-methylimidazolium methanesulfonate, N-methylbutylmorpholine bromide, 1-butyl-3-methyl... Imidazole thiocyanate, 1-butyl-3-methylimidazolium phosphate dibutyl ester, 1-octyl-3-methylimidazolium chloride, 1-decane-3-methylimidazolium chloride, 1-octadecane-3-methylimidazolium chloride, cetylpyridinium chloride, 1-hexadecyl-1-methylpyrrolidine chloride, 1-hexadecyl-2,6-dimethylpiperidine chloride, trihexyl(tetradecyl)phosphine chloride, N-hexadecyl-N-methylmorpholine chloride, 1-hexadecylthiazolyl chloride, or 1-hexadecyl-3-methylpyrazole chloride.

7. The method according to claim 1, characterized in that, The ionic liquid is 1-hexadecane-3-methylimidazolium chloride, 1-dodecane-3-methylimidazolium chloride, hexadecyltrimethylammonium bromide, 1-hexadecane-3-methylimidazolium acetate, 1-octadecane-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium thiocyanate, N-methylbutylmorpholine bromide, 1-butyl-3-methylimidazolium methanesulfonate, 1-hexylpyridine tetrafluoroborate, tetrabutylhexafluorophosphate, 1-butyl-3- Dibutyl methylimidazolium phosphate, N-butyl-N-methylpiperidine bromide, 1-butyl-1-methylpyrrolidine bromide, 1-decane-3-methylimidazolium chloride, cetylpyridinium chloride, 1-hexadecyl-1-methylpyrrolidine chloride, 1-hexadecyl-2,6-dimethylpiperidine chloride, trihexyl(tetradecyl)phosphine chloride, N-hexadecyl-N-methylmorpholine chloride, 1-hexadecylthiazolyl chloride, or 1-hexadecyl-3-methylpyrrolidine chloride.

8. The method according to claim 1, characterized in that, The mass ratio of the ionic liquid to water is (0.8~12):

30.

9. The method according to claim 1, characterized in that, The mass-to-volume ratio of the polyethylene gel fiber to the ionic liquid washing solution is 0.15~0.35 g: 1.0~3.0 mL.

10. The method according to claim 1, characterized in that, The polyethylene gel fibers are washed in an ionic liquid washing solution by ultrasonic washing or high-temperature stirring washing; the ultrasonic washing is performed at an ultrasonic temperature of 40℃~60℃, an ultrasonic power of 490~500 W, and an ultrasonic time of 0.5 h~10 h; the high-temperature stirring washing is performed at a washing temperature of 80~130℃ and a washing time of 4~6 h.

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