Composite adsorption flocculant for waste oil regeneration and preparation method thereof

Abstract

The invention discloses a composite adsorption flocculant for waste oil regeneration and a preparation method thereof, and belongs to the technical field of waste oil regeneration. The composite adsorption flocculant is prepared from the following components: 30 to 60 parts of functional modified core-shell microspheres, 6 to 18 parts of polyaluminum chloride, 0.5 to 2 parts of cationic polyacrylamide and 5 to 10 parts of sodium carbonate. According to the functionalized modified core-shell microsphere, the core is the hydroxyl-functionalized nano silicon dioxide core, and the surface of the core has a large number of hydroxyl groups derived from glycerol, which are extremely strong hydrogen bond sites; polar pollutants such as small molecular organic acids, sulfur and phosphoric acid substances in the waste oil can penetrate through the nano pore channels of the shell to reach the inner core; hydroxyl can generate multi-point and strong hydrogen bond locking with carboxyl, sulfo groups and the like of acidic substances, so that the total acid value of the waste oil is reduced, and an inner core can also react with polar functional groups containing oxygen and sulfur, so that further degradation of the waste oil is inhibited.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste oil regeneration, and specifically relates to a composite adsorption flocculant for waste oil regeneration and a preparation method thereof. Background Art

[0002] Mineral oil, the "blood" of modern industry, is widely used in many fields such as transportation, mechanical processing, and power equipment, playing key roles in lubrication, cooling, hydraulic transmission, and insulation. However, during long-term and rigorous use, these oils will gradually deteriorate in physical and chemical properties due to high-temperature oxidation, mechanical shearing, external environmental pollution, and the consumption and degradation of additives, eventually losing their performance and becoming waste oil.

[0003] Waste oil is a mixture of extremely complex components. In addition to residual base oil, its main components also include a large number of harmful impurities, including a large number of micron- and even nano-sized metal particles produced by mechanical wear; carbon soot particles produced by incomplete combustion of fuel; moisture and dust mixed in from the outside; and polar compounds such as organic acids, ketones, aldehydes, gums and asphaltene generated by oxidation, cracking and polymerization of base oils and additives under high temperature and high pressure. The presence of these impurities not only leads to an increase in the total acid value of the oil and corrosion of equipment, but also increases the viscosity of the oil, reduces the lubrication performance, and ultimately forms difficult-to-handle sludge.

[0004] Therefore, waste mineral oil has been generally classified as hazardous waste. If it is discarded or simply incinerated at will, it will not only cause a huge waste of precious oil resources, but also cause serious soil and water pollution, posing a lasting threat to the ecosystem and human health. Therefore, efficient and environmentally friendly recycling of waste oil is not only an inevitable requirement for achieving resource recycling and alleviating energy pressure, but also a key measure to protect the ecological environment and achieve sustainable development.

[0005] Existing technologies include the Chinese invention patent with application number 201910612509.4, which discloses a method for producing base lubricating oil by rapid flocculation and efficient extraction of waste lubricating oil. The treatment process is to purify the waste oil through a combination of multiple means such as flocculation, extraction, and adsorption; its technical solution requires the step-by-step and sequential addition of at least three different types of chemical flocculants, extractants, and decolorizers, and each step requires independent reaction, sedimentation, and separation units; this treatment mode not only prolongs the production cycle, increases equipment investment and operational complexity, but also makes it difficult for the various agents to achieve an ideal synergistic effect at the microscopic level.

[0006] For pollutants with very different properties in waste oil, such as polar organic acids and sulfides; and non-polar colloids, asphaltenes, and soot particles, existing technologies often adopt a divide-and-conquer strategy, that is, first use a polar adsorbent such as activated clay, silica gel, etc. to treat the acidic substances, and then add non-polar materials or extractants to treat the sludge precursor.

[0007] If two or more adsorbents are simply blended in the oil phase, the significant difference in surface energy can cause the polar and non-polar particles to agglomerate or shield each other, resulting in adsorption efficiencies that are not simply additive, but rather inhibit each other. A single adsorbent is often only effective for specific types of pollutants, such as polar or non-polar, making it difficult to simultaneously and efficiently remove the diverse and complex pollutants in waste oil. Furthermore, it is difficult to achieve simultaneous, efficient, and selective removal of both polar and non-polar substances present in waste oil.

[0008] Therefore, in order to fill the technical gap in the market, the present application provides a composite adsorption flocculant for waste oil regeneration and a preparation method thereof. Summary of the Invention

[0009] In order to solve the defects existing in the above technical solutions, the purpose of the present invention is to provide a composite adsorption flocculant for waste oil regeneration and a preparation method thereof. The composite adsorption flocculant for waste oil regeneration is composed of the following components: 30-60 parts of functionalized modified core-shell microspheres, 6-18 parts of polyaluminum chloride, 0.5-2 parts of cationic polyacrylamide, and 5-10 parts of sodium carbonate.

[0010] The molecular formula of the polyaluminium chloride is [Al2(OH) n Cl 6-n ] m , where 1≤n≤5, m≤10; The relative molecular weight of the cationic polyacrylamide is 6 million to 8 million; The content of cationic monomer in the cationic polyacrylamide is 20wt% to 25wt%; The method for preparing the functionalized modified core-shell microspheres further comprises the preparation of a hydroxyl-functionalized nano-silica core and a functionalized polystyrene shell.

[0011] The preparation method of the hydroxyl-functionalized nano-silica cores is as follows: 200 mL of anhydrous ethanol and 20 mL of deionized water are added to a reaction vessel, mechanically stirred, and mixed uniformly in a constant temperature water bath. 15 mL of concentrated aqueous ammonia is then slowly added dropwise to the mixture, and stirring is continued for 15 minutes. After stirring, 20 mL of tetraethyl orthosilicate is quickly added to the solution, which gradually turns into a milky white turbid liquid. Stirring is continued for 12 hours. After the reaction is completed, the product is purified through 3-5 cycles of centrifugation and ethanol washing. Finally, the purified white precipitate is vacuum dried for 24 hours to produce a high-purity nano-silica powder.

[0012] In a reaction vessel, 5g of dry, high-purity nanosilica powder was added, followed by 150mL of anhydrous toluene. The mixture was ultrasonically treated for 30 minutes to completely disperse the nanosilica. (3-glycidyloxypropyl)trimethoxysilane was then added to the dispersion, and the mixture was heated to 110°C under nitrogen and refluxed for 24 hours. After the reaction, unreacted and excess (3-glycidyloxypropyl)trimethoxysilane was completely removed through 3-5 centrifugation-toluene washing cycles to ensure the purity of the reaction. The purified nanosilica was then transferred to a clean reaction vessel, 100g of glycerol and 1mL of triethylamine were added as a basic catalyst, and the mixture was heated to 90°C under nitrogen and mechanically stirred for 12 hours. After the reaction is completed, the mixture is cooled to room temperature. The product is a solid suspended in viscous glycerol. A large amount of deionized water is added to dilute the mixture, and then the excess glycerol and catalyst are completely removed through 3-5 cycles of centrifugation-hot water washing-ethanol washing. The final white solid product is vacuum dried for 48 hours to prepare a hydroxyl-functionalized nano-silica core.

[0013] The preparation method of the functionalized polystyrene shell material is as follows: 0.143 g of CuBr and a magnetic stirrer are added to a dry Schlenk reaction flask, the reaction flask is immediately sealed, and the flask is connected to a Schlenk line. Three cycles of vacuuming and nitrogen filling are performed to ensure that the flask is completely oxygen-free; then, 30 mL of anisole, 10.4 g of styrene, 2.16 g of 4-tert-octylstyrene, and 0.173 g of pentamethyldiethylenetriamine are injected into the reaction flask through a deoxygenated syringe; after being fully stirred for 30 minutes, the reaction system is placed in an oil bath at 90° C. for preheating; after the temperature stabilizes, 0.3 g of a functional initiator, 6-(2-bromo-2-methyl)propionyloxy)hexyldimethylchlorosilane, is quickly injected; and the reaction is stirred continuously for 8 minutes. After 1 hour, the reaction is terminated, the reaction bottle is cooled to room temperature, and the bottle cap is opened to expose to the air to terminate the reaction; the viscous polymer solution is then diluted with a small amount of toluene, and then passed through a short column filled with neutral alumina, using toluene as an eluent; the collected colorless and transparent polymer solution is then slowly added dropwise to methanol under vigorous stirring; the polymer will precipitate; the precipitate is collected by filtration and repeatedly washed with a large amount of methanol to remove unreacted monomers and solvents; finally, the obtained white polymer is dried in a vacuum oven at 40°C for 48 hours until constant weight is reached, thereby preparing a functionalized polystyrene shell material with triethoxysilane at one end and a branched tert-octyl group on the chain.

[0014] The functionalized modified core-shell microspheres are prepared by adding 1 g of a hydroxyl-functionalized nano-silica core material and 100 mL of anhydrous toluene to a reaction vessel, followed by ultrasonic treatment for 30 minutes; then adding 2 g of a functionalized polystyrene shell polymer to the dispersion and stirring to dissolve; adding 1-2 drops of a dibutyltin dilaurate catalyst, heating the mixture to 110° C. under reflux under nitrogen protection, and reacting for 48 hours; cooling the mixture after completion of the reaction; and completely removing ungrafted free polymer through 3-5 cycles of centrifugation and toluene washing; and finally drying the purified product in a vacuum oven at 60° C. for 24 hours to obtain the functionalized modified core-shell microspheres.

[0015] The preparation method of the composite adsorption flocculant for waste oil regeneration is as follows: first, functionalized modified core-shell microspheres are added to petroleum ether as a dispersion medium, and a high-speed shear emulsifier is turned on to fully disperse the functionalized modified core-shell microspheres in the solvent to form a uniform oil phase suspension; then, sodium carbonate is added to deionized water, stirred until completely dissolved, and polyaluminum chloride is slowly added under continuous stirring. After the polyaluminum chloride is uniformly dispersed, cationic polyacrylamide is slowly added and continuously stirred. After fully stirred, a mixed solution is prepared; the mixed solution is added dropwise to the oil phase suspension through a funnel, and continuous high-speed stirring is performed. After the mixed solution is added dropwise, a mixed emulsion is prepared; finally, the uniformly mixed stable emulsion is placed in a rotary evaporator and slowly distilled to remove the dispersion medium at 50 degrees Celsius under a vacuum environment; after the rotary evaporation is completed, the product is placed in a vacuum oven, dried to a constant weight at 60 degrees Celsius, and slightly ground and crushed to prepare the composite adsorption flocculant for waste oil regeneration.

[0016] The present invention has the beneficial effects: 1. The functionalized modified core-shell microspheres in this application have a hydroxyl-functionalized nano-silica core. The core surface has a large number of hydroxyl groups derived from glycerol, which are extremely strong hydrogen bonding sites. Polar pollutants such as small molecular organic acids, sulfur, and phosphoric acid substances in waste oil can pass through the nanopores of the shell and reach the core. The hydroxyl groups will form multi-point, strong hydrogen bonds with the carboxyl and sulfonic acid groups of acidic substances to reduce the total acid value of the waste oil. The core can also interact with oxygen-containing and sulfur-containing polar functional groups to curb further deterioration of the waste oil. 2. The functionalized modified core-shell microspheres in this application have a branched tertiary octyl group on their shell, forming a highly hydrophobic and oleophilic non-polar interface, and can greatly increase the effective specific surface area of ​​the shell in contact with the waste oil. When dispersed in the waste oil, they preferentially react with the non-polar sludge precursors in the waste oil, such as waste oil oxidation products and soot particles, to form a strong van der Waals force attraction, adsorbing and locking these non-polar organic pollutants; preventing them from further aggregation into large-sized, more difficult-to-handle sludge. The core-shell structure is stable through covalent bonding, so that the microsphere structure can better perform the adsorption function of polar and non-polar substances in the waste oil. 3. The sodium carbonate in the composite adsorption flocculant of the present application can dissolve in a trace amount of water in the waste oil and hydrolyze to produce OH⁻, making the whole system weakly alkaline, which can neutralize a part of the strong acidic substances and reduce the burden of the functionalized modified core-shell microspheres. In addition, sodium carbonate can also provide an optimal pH environment for the hydrolysis of polyaluminum chloride to form the best form of aluminum hydroxide colloid and the chain extension of cationic polyacrylamide; the polyaluminum chloride as an inorganic polymer flocculant can form a large number of positively charged polynuclear hydroxyaluminum complexes in the weakly alkaline environment provided by sodium carbonate; the soot particles and colloids formed by oxidation in the waste mineral oil usually have negative charges in the oil phase, and the polyaluminum chloride The large amount of positive charge it carries will quickly neutralize these negative charges, breaking the stable suspension state formed between them due to electrostatic repulsion; making those electrically neutralized tiny particles stick together to form preliminary microflocs; and cationic polyacrylamide, as a long-chain organic polymer with positive charge, has one end adsorbed on the microflocs that have been preliminarily bonded by polyaluminum chloride or the core-shell microspheres loaded with pollutants through its positively charged groups; and its longer chain segments can extend into the oil phase to capture and adsorb another microfloc or core-shell microsphere; through this bridging effect, it is integrated into a macroscopic flocculent group of huge size and dense structure, which eventually settles rapidly under the action of gravity to achieve the regeneration of waste oil. DETAILED DESCRIPTION

[0017] To make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with Examples. The illustrative embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between the intermediate value within any stated value or stated range and any other stated value or intermediate value within the range is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0018] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0019] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0020] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0021] The "parts" indicated in the following examples are all parts by weight.

[0022] Example 1 A composite adsorption flocculant for waste oil regeneration is composed of the following components in parts by weight: 30 parts of functionalized modified core-shell microspheres, 6 parts of polyaluminum chloride, 0.5 parts of cationic polyacrylamide, and 5 parts of sodium carbonate.

[0023] The molecular formula of the polyaluminium chloride is [Al2(OH)2Cl4]5; The relative molecular weight of the cationic polyacrylamide is 6 million; The content of cationic monomer in the cationic polyacrylamide is 20 wt %.

[0024] The method for preparing the functionalized modified core-shell microspheres further comprises the preparation of a hydroxyl-functionalized nano-silica core and a functionalized polystyrene shell material.

[0025] The preparation method of the hydroxyl-functionalized nano-silica core is as follows: 200 mL of anhydrous ethanol and 20 mL of deionized water are added to a reaction vessel, mechanical stirring is started, and the mixture is mixed uniformly in a constant temperature water bath at 25°C; 15 mL of 25% concentrated ammonia water is then slowly added dropwise to the mixture, and stirring is continued for 15 minutes to create an alkaline catalytic environment required for hydrolysis; after stirring is completed, 20 mL of tetraethyl orthosilicate is quickly added to the above solution, and the solution gradually becomes a milky white turbid liquid; stirring is continued at 25°C for 12 hours to ensure full reaction completion; after the reaction is completed, the product is purified through 3-5 cycles of centrifugation-ethanol washing; finally, the purified white precipitate is dried in a vacuum oven at 60°C for 24 hours to prepare high-purity nano-silica powder.

[0026] In a round-bottom flask, add 5 g of dry, high-purity nano-silica powder, followed by 150 mL of anhydrous toluene and ultrasonic treatment for 30 minutes to completely disperse it; then add 5 g of (3-glycidyloxypropyl)trimethoxysilane to the dispersion, and heat the mixture to 110°C under nitrogen protection to reach the reflux temperature of toluene, and reflux for 24 hours. During this reaction, the trimethoxysilane groups in (3-glycidyloxypropyl)trimethoxysilane undergo a dehydration condensation reaction with the silanol groups on the surface of the nanosilica, forming a stable Si-O-Si bond and simultaneously fixing the epoxy groups on the particle surface. After the reaction, the unreacted and excess (3-glycidyloxypropyl)trimethoxysilane is completely removed through 3-5 centrifugation-toluene washing cycles to ensure the purity of the reaction. The purified nanosilica with epoxy groups on the surface is then transferred to a clean round-bottom flask and 100 g of glycerol is added. 1 mL of triethylamine is added as an alkaline catalyst to promote the nucleophilic ring-opening reaction of the hydroxyl groups on the epoxy ring. The mixture is then heated to 90°C under nitrogen protection and mechanically stirred for 12 hours. Glycerol is not only a reactant but also serves as a high-boiling point reaction solvent. In addition, one of the hydroxyl groups in the glycerol molecule attacks the epoxy ring, causing it to open, thereby introducing a structure with two new hydroxyl groups on the particle surface.

[0027] After the reaction is complete, the product is cooled to room temperature, resulting in a solid suspended in viscous glycerol. A large amount of deionized water is added for dilution, followed by 3-5 cycles of centrifugation, hot water washing, and ethanol washing to completely remove excess glycerol and catalyst. The resulting white solid product is dried in a vacuum oven at 60°C for 48 hours to obtain the hydroxyl-functionalized nanosilica core.

[0028] The preparation method of the functionalized polystyrene shell material is as follows: 0.143 g of CuBr and a magnetic stirrer are added to a dry Schlenk reaction flask, the reaction flask is immediately sealed and connected to a Schlenk line, and three cycles of vacuuming and nitrogen filling are performed to ensure that the flask is completely oxygen-free; then, 30 mL of anisole, 10.4 g of styrene, 2.16 g of 4-tert-octylstyrene, and 0.173 g of pentamethyldiethylenetriamine are injected into the reaction flask through a deoxygenated syringe; the magnetic stirrer is then used to stir the reaction flask for 30 minutes; the reaction system is preheated in an oil bath at 90° C.; after the temperature stabilizes, 0.3 g of a functional initiator, 6-(2-bromo-2-methyl)propionyloxy)hexyldimethylsilyl chloride, is rapidly injected through a syringe; after the reaction is continuously stirred for 8 hours, the reaction is terminated, the reaction flask is cooled to room temperature, and the cap is opened and exposed to air to deactivate the catalyst by oxidation, thereby terminating the reaction.

[0029] The viscous polymer solution is then diluted with a small amount of toluene and passed through a short column filled with neutral alumina using toluene as the eluent to completely remove the green copper catalyst. The collected colorless and transparent polymer solution is then slowly added dropwise to 800-1000 mL of methanol under vigorous stirring. The polymer will precipitate in the form of white flocculent or viscous matter. The precipitate is collected by filtration and washed repeatedly with a large amount of methanol several times to remove unreacted monomers and solvents. Finally, the obtained white polymer is dried in a vacuum oven at 40°C for 48 hours until constant weight is reached, thereby preparing a functionalized polystyrene shell material with triethoxysilane at one end and a branched tert-octyl group on the chain.

[0030] The functionalized modified core-shell microspheres are prepared by adding 1 g of a hydroxyl-functionalized nano-silica core material and 100 mL of anhydrous toluene to a round-bottom flask, and ultrasonically treating the mixture for 30 minutes to uniformly disperse the core material. 2 g of a functionalized polystyrene shell polymer is then added to the dispersion and stirred to dissolve the polymer. 1-2 drops of a dibutyltin dilaurate catalyst are added, and the mixture is heated to 110° C. under reflux under nitrogen protection for 48-72 hours. After the reaction is completed, the mixture is cooled. Ungrafted free polymer is completely removed through 3-5 cycles of centrifugation and toluene washing. Finally, the purified product is dried in a vacuum oven at 60° C. for 24 hours to obtain the functionalized modified core-shell microspheres.

[0031] The preparation method of the composite adsorption flocculant for waste oil regeneration is as follows: first, functionalized modified core-shell microspheres are added to petroleum ether as a dispersion medium, and a high-speed shear emulsifier is turned on to fully disperse the functionalized modified core-shell microspheres in the solvent to form a uniform oil phase suspension; then, sodium carbonate is added to deionized water, stirred until completely dissolved, and polyaluminum chloride is slowly added under continuous stirring. After the polyaluminum chloride is uniformly dispersed, cationic polyacrylamide is slowly added and continuously stirred. After fully stirred, a mixed solution is prepared; the mixed solution is added dropwise to the oil phase suspension through a funnel, and continuous high-speed stirring is performed. After the mixed solution is added dropwise, a mixed emulsion is prepared; finally, the uniformly mixed stable emulsion is placed in a rotary evaporator and slowly distilled to remove the dispersion medium at 50 degrees Celsius under a vacuum environment; after the rotary evaporation is completed, the product is placed in a vacuum oven, dried to a constant weight at 60 degrees Celsius, and slightly ground and crushed to prepare the composite adsorption flocculant for waste oil regeneration.

[0032] Example 2 A composite adsorption flocculant for waste oil regeneration is composed of the following components in parts by weight: 40 parts of functionalized modified core-shell microspheres, 10 parts of polyaluminum chloride, 1 part of cationic polyacrylamide, and 6 parts of sodium carbonate.

[0033] The molecular formula of the polyaluminium chloride is [Al2(OH)Cl5]6; The relative molecular weight of the cationic polyacrylamide is 7 million; The cationic monomer content in the cationic polyacrylamide is 22 wt %; The method for preparing the functionalized modified core-shell microspheres further includes preparing a hydroxyl-functionalized nano-silica core and a functionalized polystyrene shell material; In Example 2, the preparation method of the hydroxyl-functionalized nano-silica core, the preparation method of the functionalized polystyrene shell material, and the preparation method of the functionalized modified core-shell microspheres are all the same as those in Example 1.

[0034] Example 3 A composite adsorption flocculant for waste oil regeneration is composed of the following components in parts by weight: 50 parts of functionalized modified core-shell microspheres, 15 parts of polyaluminum chloride, 1.5 parts of cationic polyacrylamide, and 8 parts of sodium carbonate.

[0035] The molecular formula of the polyaluminium chloride is [Al2(OH)5Cl]8; The relative molecular weight of the cationic polyacrylamide is 8 million; The cationic monomer content in the cationic polyacrylamide is 25wt%; The method for preparing the functionalized modified core-shell microspheres further includes preparing a hydroxyl-functionalized nano-silica core and a functionalized polystyrene shell material; In Example 3, the preparation method of the hydroxyl-functionalized nano-silica core, the preparation method of the functionalized polystyrene shell material, and the preparation method of the functionalized modified core-shell microspheres are all the same as those in Example 1.

[0036] Example 4 A composite adsorption flocculant for waste oil regeneration is composed of the following components in parts by weight: 60 parts of functionalized modified core-shell microspheres, 18 parts of polyaluminum chloride, 2 parts of cationic polyacrylamide, and 10 parts of sodium carbonate.

[0037] The molecular formula of the polyaluminium chloride is [Al2(OH)3Cl3] 10 ; The relative molecular weight of the cationic polyacrylamide is 8 million; The cationic monomer content in the cationic polyacrylamide is 25wt%; The method for preparing the functionalized modified core-shell microspheres further includes preparing a hydroxyl-functionalized nano-silica core and a functionalized polystyrene shell material; In Example 4, the preparation method of the hydroxyl-functionalized nano-silica core, the preparation method of the functionalized polystyrene shell material, and the preparation method of the functionalized modified core-shell microspheres are all the same as those in Example 1.

[0038] Comparative Example 1 A composite adsorption flocculant for waste oil regeneration is composed of the following components in parts by weight: 15 parts of polyaluminium chloride, 1.5 parts of cationic polyacrylamide and 8 parts of sodium carbonate.

[0039] Comparative Example 1 is based on Example 3, except that the addition of functionalized modified core-shell microspheres is omitted.

[0040] Comparative Example 2 A composite adsorption flocculant for waste oil regeneration is composed of the following components by weight: 50 parts of nano-silicon dioxide, 15 parts of polyaluminium chloride, 1.5 parts of cationic polyacrylamide and 8 parts of sodium carbonate.

[0041] Comparative Example 2 is based on Example 3, except that the functionalized modified core-shell microspheres are replaced with an equal weight of ordinary high-purity nano-silica powder; the preparation method of the ordinary high-purity nano-silica powder is as follows: 200 mL of anhydrous ethanol and 20 mL of deionized water are added to a reaction vessel, mechanical stirring is turned on, and the mixture is mixed evenly in a constant temperature water bath at 25°C; 15 mL of 25% concentrated ammonia water is then slowly added dropwise to the mixture, and stirring is continued for 15 minutes to construct the alkaline catalytic environment required for hydrolysis; after stirring is completed, 20 mL of tetraethyl orthosilicate is quickly added to the above solution, and the solution gradually becomes a milky white turbid liquid; the reaction is stirred continuously at 25°C for 12 hours to ensure that the reaction is complete; after the reaction is completed, the product is purified by 3-5 cycles of centrifugation-ethanol washing; finally, the purified white precipitate is dried in a vacuum oven at 60°C for 24 hours to prepare high-purity nano-silica powder.

[0042] Comparative Example 3 A composite adsorption flocculant for waste oil regeneration is composed of the following components in parts by weight: 25 parts of hydroxyl functionalized nano-silica core material, 25 parts of functionalized polystyrene shell material, 15 parts of polyaluminum chloride, 1.5 parts of cationic polyacrylamide, and 8 parts of sodium carbonate.

[0043] Comparative Example 3 is based on Example 3, except that the functionalized modified core-shell microspheres are replaced with hydroxyl-functionalized nano-silica core materials and functionalized polystyrene shell materials; Except for the above-mentioned component differences, the preparation methods of the hydroxyl-functionalized nano-silica core material and the functionalized polystyrene shell material in Comparative Example 3 are the same as those in Example 3.

[0044] Comparative Example 4 A composite adsorption flocculant for waste oil regeneration is composed of the following components in parts by weight: 50 parts of modified core-shell microspheres, 15 parts of polyaluminum chloride, 1.5 parts of cationic polyacrylamide, and 8 parts of sodium carbonate.

[0045] Comparative Example 4 is based on Example 3, except that, in the preparation process of the modified core-shell microspheres, ordinary high-purity nano-silica powder was used, and the nano-silica core material was not functionalized with hydroxyl groups; Except for the above-mentioned differences in components, the preparation methods of the functionalized polystyrene shell material and the functionalized modified core-shell microspheres in Comparative Example 4 are the same as those in Example 3.

[0046] Comparative Example 5 A composite adsorption flocculant for waste oil regeneration is composed of the following components in parts by weight: 50 parts of functionalized modified core-shell microspheres, 15 parts of polyaluminum chloride, 1.5 parts of cationic polyacrylamide, and 8 parts of sodium carbonate.

[0047] Comparative Example 5 is based on Example 3, except that 4-tert-octylstyrene is not used in the preparation of the functionalized modified core-shell microspheres, and the prepared functionalized polystyrene shell material does not have a branched tert-octyl group chain; Except for the above-mentioned differences in components, the preparation method of the hydroxyl-functionalized nano-silica core and the preparation method of the functionalized modified core-shell microspheres in Comparative Example 5 are the same as those in Example 1.

[0048] Test example Refer to GB / T 6540 "Petroleum Products Color Determination Method" to complete the color measurement of waste oil before and after regeneration; Refer to GB / T GB / T 265 "Petroleum products kinematic viscosity determination and dynamic viscosity calculation method" to complete the kinematic viscosity measurement of waste oil before and after regeneration; Refer to GB / T 264 "Determination of acid value of petroleum products" to complete the determination of acid value of waste oil before and after regeneration; Refer to GB / T 17040 "Determination of sulfur content in petroleum and petroleum products" to complete the determination of sulfur content in waste oil before and after regeneration; With reference to GB / T 2433 "Determination of sulfated ash content of lubricating oils containing additives", the ash content before and after waste oil regeneration was determined.

[0049] The waste oil of the blank control group of the test example was taken from a standard parts production plant.

[0050] The specific waste oil regeneration process is as follows: the waste oil is pumped into a reactor with stirring and heating functions. After the waste oil temperature is raised to 60 degrees Celsius, the rotation speed is maintained at 200 rpm, and a composite adsorption flocculant accounting for 1.5% of the total weight of the waste oil is added. The high-speed stirring is continued for 15 minutes; then the stirring speed is reduced to 40 rpm. After sufficient reaction for 45 minutes, the stirring is stopped; the material in the reactor is allowed to settle in a completely static state for 3 hours; then the clear regenerated waste oil on the upper layer is extracted to complete the waste oil regeneration process.

[0051] The test results of various indicators are shown in Table 1: Table 1 Analysis of the regeneration performance of the composite adsorption flocculants of Examples 1-4 and Comparative Examples 1-4: Examples 1-4 all achieved excellent waste oil regeneration effects, and the color, kinematic viscosity, acid value, sulfur content and ash content of the treated oils were greatly optimized; among them, Example 3 showed the best adsorption performance in all indicators, and was able to achieve the regeneration of waste oil to the greatest extent.

[0052] The components of Comparative Example 1 omit the addition of functionalized modified core-shell microspheres, and the remaining components act as flocculating and settling agents, which can only remove some suspended impurities. They are completely incapable of removing soluble acidic substances, sulfides, and tiny non-polar pollutants that serve as sludge precursors in the waste oil, resulting in an acid value and sulfur content that are not much different from those of the blank control group. This shows that the functionalized modified core-shell microspheres in the technical solution of the present application, as core adsorbents, are the fundamental prerequisite for achieving deep purification of waste oil.

[0053] Comparative Example 2 is based on Comparative Example 1, but nano-silicon dioxide is also added. Although the acid value and sulfur content are reduced to a certain extent, the effect is far inferior to that of Example 3. The surface of ordinary nano-silica is polar and can only adsorb polar acidic substances to a very limited extent. It also lacks adsorption methods for non-polar sludge precursors that cause color and viscosity problems, and cannot achieve the synergistic and efficient removal of two types of pollutants at the same time.

[0054] In Comparative Example 3, the functionalized core and shell materials are simply physically mixed and then added. Its various adsorption capacity indicators are even worse than those of Comparative Example 2 using ordinary silica. The reason is that in the waste oil environment, the highly polar hydroxyl functionalized core will quickly agglomerate due to its oleophobicity, causing its effective adsorption sites to be covered and ineffective; while the highly lipophilic functionalized polystyrene shell will directly dissolve in the waste oil and lose its structural function as a shell; if a structurally stable core-shell whole cannot be established through covalent bonding, the microspheres cannot fully exert their adsorption function for polar and non-polar substances in the waste oil; and simple physical blending cannot achieve good treatment of waste oil regeneration. That is, only by "bundling" the two into an inseparable core-shell whole through stable covalent bonding can they be forced to work synergistically at the nanoscale.

[0055] The difference between Comparative Example 5 and Example 3 is that the functionalized polystyrene shell material prepared in Comparative Example 5 does not have a branched tert-octyl group on its chain; although the shell of Comparative Example 5 also has certain hydrophobic and lipophilic properties, it lacks the "spatial capture effect" and "enhanced van der Waals force points" formed by the huge side chain provided by the tert-octyl group. Therefore, its ability to capture these non-polar pollutants will be greatly reduced; therefore, the chromaticity deteriorates sharply from 2.0 in Example 3 to 5.6, and the viscosity also deteriorates significantly from 16.97 to 31.52. Its effect is much worse than that of Example 3, but it is still slightly better than that of Comparative Example 1 without any adsorbent, indicating that the capture ability of Comparative Example 5 for non-polar pollutants will be greatly reduced; this shows that not any combination of core-shell structures can achieve the beneficial effects of the technical solution of this application.

[0056] Comparative Example 4 has a microsphere structure and has the same oleophilic shell as Example 3, so it performs well in adsorbing non-polar sludge precursors, resulting in significant improvement in chromaticity and viscosity. In the preparation process of the modified core-shell microspheres of Comparative Example 4, ordinary high-purity nano-silica powder is used, and the nano-silica core material is not functionalized with hydroxyl groups. Its core lacks a large number of highly active hydroxyl adsorption sites, resulting in a significant reduction in its adsorption capacity for acid value and sulfur content; the possible reason is that: the core is a hydroxyl-functionalized nano-silica core, and the surface of the core has a large number of hydroxyl groups derived from glycerol, which are extremely strong hydrogen bonding sites; and polar pollutants such as small molecular organic acids and sulfur / phosphoric acid substances in the waste oil can pass through the nanopores of the shell and reach the core; the hydroxyl groups will undergo multi-point, strong hydrogen bonding with the carboxyl groups and sulfonic acid groups of the acidic substances to reduce the total acid value of the waste oil, and the core can also react with oxygen-containing and sulfur-containing polar functional groups; thereby curbing further deterioration of the waste oil.

[0057] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite adsorption flocculant for waste oil regeneration, characterized in that: The composite adsorption flocculant is composed of the following components: 30-60 parts of functionalized modified core-shell microspheres, 6-18 parts of polyaluminum chloride, 0.5-2 parts of cationic polyacrylamide, and 5-10 parts of sodium carbonate.

2. A composite adsorption flocculant for waste oil regeneration according to claim 1, characterized in that: The composite adsorption flocculant is composed of the following components: 50 parts of functionalized modified core-shell microspheres, 15 parts of polyaluminum chloride, 1.5 parts of cationic polyacrylamide, and 8 parts of sodium carbonate.

3. The composite adsorption flocculant for waste oil regeneration according to claim 1, characterized in that: The molecular formula of the polyaluminium chloride is [Al2(OH) n Cl 6-n ] m , where 1≤n≤5, m≤10.

4. The composite adsorption flocculant for waste oil regeneration according to claim 1, characterized in that: The relative molecular weight of the cationic polyacrylamide is 6 million to 8 million.

5. The composite adsorption flocculant for waste oil regeneration according to claim 1, characterized in that: The content of cationic monomer in the cationic polyacrylamide is 20 wt % to 25 wt %.

6. The composite adsorption flocculant for waste oil regeneration according to claim 1, characterized in that: The functionalized modified core-shell microspheres are prepared by the following method: adding a hydroxyl-functionalized nano-silica core material and anhydrous toluene to a reaction vessel, and then ultrasonically treating the mixture; then adding a polymer of a functionalized polystyrene shell material to the dispersion, stirring and dissolving the polymer; adding 1-2 drops of dibutyltin dilaurate catalyst, and heating the mixture to 110° C. under reflux under nitrogen protection for 48 hours; and cooling the mixture after the reaction is complete. The purified product was vacuum dried to a constant weight through 3-5 cycles of centrifugation and toluene washing, thereby preparing functionalized modified core-shell microspheres.

7. The composite adsorption flocculant for waste oil regeneration according to claim 6, characterized in that: The hydroxyl-functionalized nano-silica core is prepared by the following method: adding high-purity nano-silica powder to a reaction vessel, then adding anhydrous toluene, and ultrasonically treating the mixture to completely disperse it; then adding (3-glycidyloxypropyl)trimethoxysilane to the dispersion, heating the mixture to 110°C under nitrogen protection, and reflux reacting for 24 hours; after the reaction is completed, the mixture is subjected to 3-5 cycles of centrifugation and toluene washing; then the purified nano-silica is transferred to a clean reaction vessel, glycerol and triethylamine are added; and the mixture is heated to 90°C under nitrogen protection and mechanically stirred for 12 hours; after the reaction is completed, the mixture is cooled to room temperature, diluted with a large amount of deionized water, and then subjected to 3-5 cycles of centrifugation, hot water washing, and ethanol washing; and the resulting white solid product is vacuum dried for 48 hours to prepare the hydroxyl-functionalized nano-silica core.

8. The composite adsorption flocculant for waste oil regeneration according to claim 7, characterized in that: The high-purity nano-silica powder is prepared by the following method: 200 mL of anhydrous ethanol and 20 mL of deionized water are added to a reaction vessel, mechanical stirring is started, and the mixture is mixed uniformly in a constant temperature water bath; 15 mL of concentrated ammonia water is then slowly added dropwise to the mixture, and stirring is continued for 15 minutes; after stirring is completed, 20 mL of tetraethyl orthosilicate is quickly added to the solution, and the solution gradually turns into a milky white turbid liquid; The reaction was stirred continuously for 12 hours. After the reaction, the product was purified by 3-5 cycles of centrifugation and ethanol washing. Finally, the purified white precipitate was vacuum dried for 24 hours to obtain high-purity nano-silica powder.

9. The composite adsorption flocculant for waste oil regeneration according to claim 6, characterized in that: The functionalized polystyrene shell material is prepared by the following method: adding CuBr and a magnetic stirrer to a dry Schlenk reaction flask, sealing the reaction flask, and connecting it to a Schlenk line. Three cycles of vacuuming and nitrogen filling are performed to ensure that the flask is completely oxygen-free; then, anisole, styrene, 4-tert-octylstyrene, and pentamethyldiethylenetriamine are injected into the reaction flask through a deoxygenated syringe; after thorough stirring for 30 minutes, the reaction system is preheated in an oil bath at 90° C.; after the temperature stabilizes, 6-(2-bromo-2-methyl)propionyloxy)hexyldimethylsilyl chloride is injected; and the reaction is stirred continuously for 8 minutes. After 1 hour, the reaction is terminated, the reaction bottle is cooled to room temperature and exposed to the air; the viscous polymer solution is then diluted with a small amount of toluene, and then passed through a short column filled with neutral alumina, using toluene as the eluent; the collected colorless and transparent polymer solution is then slowly added dropwise to methanol under vigorous stirring; the polymer will precipitate; the precipitate is collected by filtration and repeatedly washed with a large amount of methanol; finally, the obtained white polymer is dried in vacuum until constant weight, thereby preparing a functionalized polystyrene shell material.

10. The composite adsorption flocculant for waste oil regeneration according to any one of claims 1 to 9, characterized in that: The preparation method of the composite adsorption flocculant for waste oil regeneration includes the following steps: first, functionalized modified core-shell microspheres are added to petroleum ether as a dispersion medium, and a high-speed shear emulsifier is started to fully disperse the functionalized modified core-shell microspheres in the solvent to form a uniform oil phase suspension; then, sodium carbonate is added to deionized water, stirred until completely dissolved, and polyaluminum chloride is slowly added under continuous stirring. After the polyaluminum chloride is uniformly dispersed, cationic polyacrylamide is slowly added and continuously stirred until fully stirred to prepare a mixed solution; the mixed solution is added dropwise to the oil phase suspension through a funnel, and continuous high-speed stirring is performed. After the mixed solution is added dropwise, a mixed emulsion is prepared; finally, the uniformly mixed stable emulsion is placed in a rotary evaporator and slowly distilled to remove the dispersion medium at 50 degrees Celsius under a vacuum environment; after the rotary evaporation is completed, the product is placed in a vacuum oven, dried to a constant weight at 60 degrees Celsius, and slightly ground and crushed to prepare the composite adsorption flocculant for waste oil regeneration.

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