Environmentally friendly aluminum paint stripper and preparation method thereof

Abstract

The invention discloses an environmentally friendly aluminum paint stripper and a preparation method thereof in the field of paint stripper technology, including the following components by weight: 15-20 parts of alkaline substances, 8-10 parts of catalyst promoters, 6-8 parts of cosolvents, 3-5 parts of de-agent promoters, 3.6-4.6 parts of surfactants and 200-230 parts of deionized water. The present invention proposes to prepare a water-based environmentally friendly alkaline paint stripper by selecting a high-boiling-point low-toxicity component, thereby achieving the technical effect of paint stripper environmental protection, and preparing a catalyst promoter at the same time, connecting a carbon shell with nano-iron tetroxide as the core, loading an alkaline metal oxide, and improving the degradation rate of the paint film, thereby reducing the paint stripping time and reducing the substrate loss.

Description

Technical Field

[0001] The invention belongs to the technical field of paint strippers, and in particular relates to an environmentally friendly aluminum paint stripper and a preparation method thereof. Background Art

[0002] In daily life, aluminum products are usually sprayed with paint to form a protective paint film on the surface, which has functions such as decoration, anti-corrosion, and marking. During long-term use, the paint film will be affected by various environmental factors, and will age, peel, crack, etc., making the paint film no longer have the desired functions. At this time, it is necessary to remove the paint and repaint. Paint stripping methods are divided into: chemical paint stripping, laser paint stripping, and mechanical removal. Among them, mechanical removal is difficult to completely remove the paint, and the cost of laser paint stripping is relatively high. Chemical paint stripping has the advantages of low cost and good paint stripping effect, making it the most commonly used paint stripping technology. Paint strippers commonly used in chemical paint stripping It is mainly divided into solvent-based and water-based types. Although the solvent-based type has the advantages of easy use, high paint stripping efficiency, and low corrosion to metals, it usually contains highly toxic and volatile organic matter such as phenol, dichloromethane, and aromatic compounds. With the improvement of the quality of life, people's environmental protection awareness is increasing, so the demand for environmentally friendly paint strippers is growing; alkaline paint strippers are mainly sodium hydroxide, supplemented by co-solvents, surfactants and corrosion inhibitors, and paint stripping is carried out through saponification reaction and emulsification. Although the raw materials are cheap and easy to obtain, and environmentally friendly, the corrosiveness of the strong alkali can easily damage the substrate, and the paint stripping time is long, making it difficult to reuse.

[0003] The existing technology currently has the following main problems: 1. Common paint strippers are highly toxic; 2. Alkaline paint strippers take a long time to strip paint and are prone to damage the substrate. Summary of the invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides an environmentally friendly aluminum paint stripper and a preparation method thereof. In order to solve the problem of high toxicity of commonly used paint strippers, the present invention proposes to prepare a water-based environmentally friendly alkaline paint stripper by selecting high-boiling point and low-toxicity components, thereby achieving the technical effect of environmental protection of the paint stripper. At the same time, a promoting catalyst is prepared, with nano-ferroferric oxide as the core connected to a carbon shell, loaded with alkaline metal oxides, to increase the degradation rate of the paint film, thereby reducing the paint stripping time and reducing the substrate loss.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present invention is as follows: The present invention proposes an environmentally friendly aluminum paint stripper and a preparation method thereof, wherein the environmentally friendly aluminum paint stripper comprises the following components in parts by weight: 15-20 parts of an alkaline substance, 8-10 parts of a promoter catalyst, 6-8 parts of a cosolvent, 3-5 parts of a stripping aid, 3.6-4.6 parts of a surfactant and 200-230 parts of deionized water;

[0006] Preferably, the alkaline substance includes at least one of sodium hydroxide and potassium hydroxide;

[0007] Preferably, the promoting catalyst is a nano-ferroferric oxide core connected to a carbon shell, and is loaded with barium oxide and calcium oxide; it is prepared from the following components: 6.5-7.5 parts of ferric chloride hexahydrate, 18-20 parts of ammonium acetate, 1.5-2.5 parts of sodium citrate dihydrate, 20-26 parts of zinc nitrate hexahydrate, 15-17 parts of 2-methylimidazole, 6-7.5 parts of calcium chloride and 2.5-3.5 parts of barium chloride;

[0008] Preferably, the cosolvent includes at least one of ethylene glycol, ethylene glycol butyl ether, and diethylene glycol butyl ether;

[0009] Preferably, the release aid is a combination of sodium metasilicate and trisodium phosphate in a mass ratio of 1:1;

[0010] Preferably, the surfactant includes at least one of AEO-3, AEO-7, AEO-9, and cetyltrimethylammonium bromide.

[0011] Preferably, the preparation method of the promoting catalyst specifically comprises the following steps:

[0012] S1. Evenly mix ferric chloride hexahydrate, ammonium acetate and sodium citrate dihydrate to obtain a reaction raw material, add the reaction raw material to ethylene glycol in an amount of 0.08-0.1 g / mL, stir in an oil bath, and obtain a reaction solution;

[0013] S2, transferring the reaction solution obtained in S1 to an autoclave, heating for reaction, cooling to room temperature to obtain black powder, washing with anhydrous ethanol, and then vacuum drying to obtain nano-iron tetroxide;

[0014] S3, uniformly mix zinc nitrate hexahydrate and 2-methylimidazole to obtain a mixture, add it to a methanol solution in an amount of 8-10 mg / mL, ultrasonically disperse for 10-15 minutes, then add the nano-iron tetroxide obtained in S2, stir in a water bath, centrifuge to obtain a precipitate, dry it, perform magnetic separation to remove non-magnetic and weakly magnetic components, wash with anhydrous ethanol, and vacuum dry it to obtain ZIF-8@Fe3O4;

[0015] S4, adding ZIF-8@Fe3O4 obtained in S3 to a methanol solution at an addition amount of 20-30 mg / mL, then adding calcium chloride and barium chloride, stirring in a water bath, then adjusting the pH to 11-12 with 1 mol / L sodium hydroxide solution, slowly stirring for 2-3 h, centrifuging to obtain a precipitate and drying it, performing magnetic separation to remove non-magnetic and weakly magnetic components, washing with anhydrous ethanol, and vacuum drying to obtain Ba / Ca / ZIF-8@Fe3O4;

[0016] S5. The precursor obtained in S4 is calcined for 100 minutes in a nitrogen atmosphere, cooled to room temperature, calcined for 15 minutes, and cooled to room temperature to obtain BaO / CaO / C@Fe3O4 as a promoting catalyst.

[0017] Preferably, in S1, the oil bath stirring temperature is 165-175°C, the speed is 160-180 rpm, and the time is 60-80 min.

[0018] Preferably, in S2, the heating reaction temperature is 200-220°C and the time is 14-16h.

[0019] Preferably, in S3, the water bath stirring temperature is 65-75°C, the speed is 80-100 rpm, and the time is 25-35 min.

[0020] Preferably, in S4, the water bath stirring temperature is 50-60°C, the speed is 60-80 rpm, and the time is 60-80 min.

[0021] Preferably, in S5, the primary calcination temperature is 600-650°C, and the secondary calcination temperature is 950-1000°C.

[0022] The present invention also provides an environmentally friendly aluminum paint stripper and a preparation method thereof, which specifically comprises the following steps:

[0023] Add alkaline substances into deionized water, stir and dissolve in a 60-70°C water bath at 50-60rpm to obtain alkaline solution, add accelerator catalyst, co-solvent, de-painting aid and surfactant into the alkaline solution, stir evenly to obtain an environmentally friendly aluminum paint stripper.

[0024] The beneficial effects achieved by the present invention are as follows: the present invention prepares a water-based environmentally friendly alkaline paint stripper by selecting a high-boiling-point and low-toxicity component, reduces the use of organic components, reduces the toxicity of the paint stripper, and simultaneously prepares a catalyst, uses nano-ferroferric oxide as a core to connect a carbon shell, loads alkaline metal oxides, increases the degradation rate of the paint film, thereby reducing the paint stripping time, reducing the substrate loss, and using its high low-temperature activity to reduce the paint stripping temperature of the paint stripper, further reducing the volatilization of organic components in the paint stripper, further reducing the toxicity, and achieving an environmentally friendly and safe effect; the present invention prepares nano-ferroferric oxide as a core, has good magnetic properties, and uses zinc nitrate hexahydrate to supply Zn 2+ , the organic metal framework was synthesized with 2-methylimidazole, and then Ba was adsorbed 2+ and Ca 2+ In the metal organic framework, OH -Sedimentation, through a single calcination, the organic metal framework is transformed into a carbon shell. The secondary calcination temperature is higher than the boiling point of Zn. A short high temperature removes it and leaves a porous structure, which improves the reaction activity and reduces the reaction temperature. The carbon shell can fix and protect the generated BaO and CaO, reduce losses during use, and facilitate recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The result diagram of paint stripping time of Examples 1-3 and Comparative Examples 1-2 of the present invention;

[0026] Figure 2 The result diagram of paint stripping time at different temperatures of Example 1 and Comparative Example 1 of the present invention;

[0027] Figure 3 The result diagram of the corrosion rate of Examples 1-3 and Comparative Examples 1-2 of the present invention;

[0028] Figure 4 This is a SEM image of the promoted catalyst recovered after the paint stripping experiment in Example 1.

[0029] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.

[0032] The experimental methods in the following examples are conventional methods unless otherwise specified; the experimental materials used in the following examples are purchased from commercial channels unless otherwise specified.

[0033] Example 1

[0034] An environmentally friendly aluminum paint stripper includes the following components in parts by weight: 15 parts of sodium hydroxide, 8 parts of a catalytic promoter, 3 parts of ethylene glycol, 3 parts of ethylene glycol butyl ether, 1.5 parts of sodium metasilicate, 1.5 parts of trisodium phosphate, 1.6 parts of AEO-3, 2 parts of cetyltrimethylammonium bromide and 200 parts of deionized water;

[0035] S1. Evenly mix ferric chloride hexahydrate, ammonium acetate and sodium citrate dihydrate to obtain a reaction raw material, add the reaction raw material into ethylene glycol in an amount of 0.08 g / mL, stir in an oil bath at 165° C. and 160 rpm for 60 min to obtain a reaction solution;

[0036] S2, transferring the reaction solution obtained in S1 to an autoclave, heating the reaction at 200°C for 14 hours, cooling to room temperature to obtain a black powder, washing it with anhydrous ethanol, and then vacuum drying it to obtain nano-iron tetroxide;

[0037] S3, zinc nitrate hexahydrate and 2-methylimidazole were uniformly mixed to obtain a mixture, and added to a methanol solution at an addition amount of 8 mg / mL, and ultrasonically dispersed for 10 minutes, and then the nano-iron tetroxide obtained in S2 was added, and stirred at 80 rpm in a 65°C water bath for 25 minutes, centrifuged to obtain a precipitate, dried, and magnetically separated to remove non-magnetic and weakly magnetic components, washed with anhydrous ethanol, and vacuum dried to obtain ZIF-8@Fe3O4;

[0038] S4, adding 20 mg / mL of ZIF-8@Fe3O4 obtained in S3 to a methanol solution, followed by adding calcium chloride and barium chloride, stirring at 60 rpm in a 50°C water bath for 60 min, then adjusting the pH to 112 with 1 mol / L sodium hydroxide solution, slowly stirring for 2 h, centrifuging to obtain a precipitate and drying it, performing magnetic separation to remove non-magnetic and weakly magnetic components, washing with anhydrous ethanol, and vacuum drying to obtain Ba / Ca / ZIF-8@Fe3O4;

[0039] S5. The precursor obtained in S4 is calcined at 600°C for 100 min in a nitrogen atmosphere, cooled to room temperature, calcined at 950°C for 15 min, and cooled to room temperature to obtain BaO / CaO / C@Fe3O4 as a promoting catalyst.

[0040] The present invention also provides an environmentally friendly aluminum paint stripper and a preparation method thereof, which specifically comprises the following steps:

[0041] The alkaline substance is added into deionized water, stirred and dissolved in a 60°C water bath at 50 rpm to obtain an alkaline solution, and an accelerator catalyst, a co-solvent, a stripping aid, and a surfactant are added into the alkaline solution, and stirred evenly to obtain an environmentally friendly aluminum paint stripper.

[0042] Example 2

[0043] An environmentally friendly aluminum paint stripper includes the following components in parts by weight: 20 parts of potassium hydroxide, 10 parts of a catalyst promoter, 4 parts of ethylene glycol, 4 parts of ethylene glycol butyl ether, 2.5 parts of sodium metasilicate, 2.5 parts of trisodium phosphate, 1.6 parts of AEO-7, 3 parts of cetyltrimethylammonium bromide and 230 parts of deionized water;

[0044] S1. Evenly mix ferric chloride hexahydrate, ammonium acetate and sodium citrate dihydrate to obtain a reaction raw material, add the reaction raw material into ethylene glycol in an amount of 0.1 g / mL, stir in an oil bath at 175° C. and 180 rpm for 80 min to obtain a reaction solution;

[0045] S2, transfer the reaction solution obtained in S1 to an autoclave, heat at 220°C for 16 hours, cool to room temperature to obtain black powder, wash with anhydrous ethanol, and then vacuum dry to obtain nano-iron tetroxide;

[0046] S3, zinc nitrate hexahydrate and 2-methylimidazole were uniformly mixed to obtain a mixture, and the mixture was added to a methanol solution at an addition amount of 10 mg / mL, and ultrasonic dispersion was performed for 15 minutes, and then the nano-iron tetroxide obtained in S2 was added, and the mixture was stirred at 100 rpm in a 75°C water bath for 35 minutes, and the precipitate was centrifuged and dried, and non-magnetic and weakly magnetic components were removed by magnetic separation, and the mixture was washed with anhydrous ethanol, and vacuum dried to obtain ZIF-8@Fe3O4;

[0047] S4, adding 30 mg / mL of ZIF-8@Fe3O4 obtained in S3 to a methanol solution, followed by adding calcium chloride and barium chloride, stirring at 80 rpm for 80 min in a 60°C water bath, adjusting the pH to 12 with 1 mol / L sodium hydroxide solution, stirring slowly for 3 h, centrifuging and drying the precipitate, performing magnetic separation to remove non-magnetic and weakly magnetic components, washing with anhydrous ethanol, and vacuum drying to obtain Ba / Ca / ZIF-8@Fe3O4;

[0048] S5. The precursor obtained in S4 is calcined at 650°C for 100 min in a nitrogen atmosphere, cooled to room temperature, calcined for a second time at 1000°C for 15 min, and cooled to room temperature to obtain BaO / CaO / C@Fe3O4, which is a promoting catalyst.

[0049] The present invention also provides an environmentally friendly aluminum paint stripper and a preparation method thereof, which specifically comprises the following steps:

[0050] The alkaline substance is added into deionized water, stirred and dissolved in a 70°C water bath at 60 rpm to obtain an alkaline solution, and an accelerator catalyst, a co-solvent, a stripping aid, and a surfactant are added into the alkaline solution, and stirred evenly to obtain an environmentally friendly aluminum paint stripper.

[0051] Example 3

[0052] An environmentally friendly aluminum paint stripper includes the following components in parts by weight: 9 parts of sodium hydroxide, 9 parts of potassium hydroxide, 9 parts of a catalytic promoter, 7 parts of diethylene glycol butyl ether, 2 parts of sodium metasilicate, 2 parts of trisodium phosphate, 1.2 parts of AEO-9, 3 parts of hexadecyltrimethylammonium bromide and 215 parts of deionized water;

[0053] S1. Evenly mix ferric chloride hexahydrate, ammonium acetate and sodium citrate dihydrate to obtain a reaction raw material, add the reaction raw material into ethylene glycol in an amount of 0.09 g / mL, stir in an oil bath at 170° C. and 170 rpm for 70 min to obtain a reaction solution;

[0054] S2, transfer the reaction solution obtained in S1 to an autoclave, heat at 210°C for 15 hours, cool to room temperature to obtain black powder, wash with anhydrous ethanol, and then vacuum dry to obtain nano-iron tetroxide;

[0055] S3, zinc nitrate hexahydrate and 2-methylimidazole were uniformly mixed to obtain a mixture, which was added to a methanol solution at an addition amount of 9 mg / mL, and ultrasonically dispersed for 12.5 min, and then the nano-iron tetroxide obtained in S2 was added, and the mixture was stirred at 90 rpm in a 70°C water bath for 30 min, and the precipitate was centrifuged and dried, and magnetic separation was performed to remove non-magnetic and weakly magnetic components, and the mixture was washed with anhydrous ethanol, and vacuum dried to obtain ZIF-8@Fe3O4;

[0056] S4, adding 25 mg / mL of ZIF-8@Fe3O4 obtained in S3 to a methanol solution, followed by adding calcium chloride and barium chloride, stirring at 70 rpm in a 55°C water bath for 70 min, then adjusting the pH to 11.5 with 1 mol / L sodium hydroxide solution, stirring slowly for 2.5 h, centrifuging to obtain a precipitate and drying it, performing magnetic separation to remove non-magnetic and weakly magnetic components, washing with anhydrous ethanol, and vacuum drying to obtain Ba / Ca / ZIF-8@Fe3O4;

[0057] S5. The precursor obtained in S4 was calcined at 630°C for 100 min in a nitrogen atmosphere, cooled to room temperature, and then calcined at 960°C for 15 min. The mixture was cooled to room temperature to obtain BaO / CaO / C@Fe3O4, which is a catalytic catalyst.

[0058] The present invention also provides an environmentally friendly aluminum paint stripper and a preparation method thereof, which specifically comprises the following steps:

[0059] The alkaline substance is added into deionized water, stirred and dissolved in a 65°C water bath at 55 rpm to obtain an alkaline solution, and an accelerator catalyst, a co-solvent, a stripping aid, and a surfactant are added into the alkaline solution, and stirred evenly to obtain an environmentally friendly aluminum paint stripper.

[0060] Comparative Example 1

[0061] This comparative example provides a paint stripper, which differs from Example 1 only in that all components do not contain 2-methylimidazole, that is, the promoting catalyst is only sintered and does not include a carbon shell, and the remaining components and component contents are the same as those in Example 1.

[0062] Comparative Example 2

[0063] This comparative example provides a paint stripper, which differs from Example 1 only in that no secondary calcination is performed in step S5, and the remaining components and component contents are the same as those in Example 1.

[0064] Experimental example

[0065] The steps for processing aluminum sheets are as follows:

[0066] The aluminum sheet is cleaned, polished and dried, and then evenly painted on one side of the metal aluminum sheet. The thickness of the paint film is basically consistent, and it is cut into aluminum sheets of equal area to form painted aluminum sheets.

[0067] 1. Time Test

[0068] Three painted aluminum sheets were taken from each group and immersed in the paint strippers obtained in Examples 1-3 and Comparative Examples 1-2, respectively. Paint stripping experiments were carried out in a 60° C. water bath. The average of the time required for the paint film to be completely detached from each group was taken and recorded as the paint stripping time.

[0069] Figure 1 It is a result graph of the paint stripping time of Examples 1-3 and Comparative Examples 1-2 of the present invention; as shown in the figure, the paint stripping time of Examples 1-3 and Comparative Examples 1-2 are 9.3min, 9.2min, 9.6min, 17.8min, and 13.3min, respectively; the paint stripping time of Example 1-3 is significantly shorter than that of Example 1-2, indicating that the use of 2-methylimidazole and the secondary calcination process increase the degradation rate of the paint film and reduce the paint stripping time.

[0070] 2. Temperature test

[0071] Take 3 painted aluminum sheets in each group and immerse them in the paint stripping agent obtained in Example 1 and Comparative Example 1 respectively. Carry out paint stripping experiments under water bath conditions of 30°C, 40°C, 50°C, 60°C and 70°C. Take the average of the time for the paint film to be completely detached from each group, which is recorded as the paint stripping time.

[0072] Figure 2It is a result diagram of paint stripping time at different temperatures for Example 1 and Comparative Example 1 of the present invention; as shown in the figure, the paint stripping time for Example 1 at 30°C, 40°C, 50°C, 60°C and 70°C are 12.6min, 9.3min, 8.7min, 8.3min and 8.1min respectively; the paint stripping time for Example 2 at 30°C, 40°C, 50°C, 60°C and 70°C are 22.6min, 20.9min, 19.3min, 17.8min and 17.1min respectively; it can be seen that the paint stripping time for Example 1 tends to be stable at 40°C, and the paint stripping time for Comparative Example 1 tends to be stable at 60°C, the use of 2-methylimidazole reduces the degradation temperature of the paint film, and paint stripping at a lower temperature can reduce the volatilization of organic solvents and reduce toxicity.

[0073] 3. Corrosion test

[0074] Take 3 painted aluminum sheets in each group and immerse them in the paint strippers obtained in Examples 1-3 and Comparative Examples 1-2 respectively. Perform paint stripping experiments in a water bath at 60°C. Take the average mass of the aluminum sheets after the paint film is completely removed from each group, and record it as the mass after paint stripping. Take the mass of aluminum sheets of the same aluminum material and area after cleaning by the same process as the mass before paint stripping, and calculate the corrosion rate by the following formula:

[0075] Corrosion rate = (mass before paint stripping - mass after paint stripping) / mass before paint stripping × 100%.

[0076] Figure 3 The result diagram of the corrosion rate of Examples 1-3 and Comparative Example 1-2 of the present invention is shown; as shown in the figure, the corrosion rates of Examples 1-3 and Comparative Example 1-2 are 0.62%, 0.65%, 0.61%, 1.33% and 0.92%, respectively; the corrosion rate of Example 1-3 is significantly lower than that of Example 1-2, and the use of 2-methylimidazole and the secondary calcination process reduce the paint stripping time, thereby reducing the corrosion of the strong alkali to the aluminum material.

[0077] 4. Figure 4 This is a SEM image of the promoting catalyst recovered after the paint stripping experiment in Example 1. As shown in the figure, the recovered promoting catalyst has good dispersion, intact morphology and good stability.

[0078] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

[0079] The present invention and its implementation methods are described above, which is not restrictive. The drawings are only one of the implementation methods of the present invention, and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. An environmentally friendly aluminum paint stripper, characterized in that: The invention comprises the following components in parts by weight: 15-20 parts of alkaline substance, 8-10 parts of promoting catalyst, 6-8 parts of co-solvent, 3-5 parts of debonding agent, 3.6-4.6 parts of surfactant and 200-230 parts of deionized water; The alkaline substance includes at least one of sodium hydroxide and potassium hydroxide; The catalyst has nano-ferroferric oxide as the core and a carbon shell, and is loaded with barium oxide and calcium oxide. The catalyst is prepared from the following components: 6.5-7.5 parts of ferric chloride hexahydrate, 18-20 parts of ammonium acetate, 1.5-2.5 parts of sodium citrate dihydrate, 20-26 parts of zinc nitrate hexahydrate, 15-17 parts of 2-methylimidazole, 6-7.5 parts of calcium chloride and 2.5-3.5 parts of barium chloride. The co-solvent comprises at least one of ethylene glycol, ethylene glycol butyl ether and diethylene glycol butyl ether; The debonding agent is a combination of sodium metasilicate and trisodium phosphate in a mass ratio of 1:1; The surfactant includes at least one of AEO-3, AEO-7, AEO-9, and cetyltrimethylammonium bromide.

2. A method for preparing an environmentally friendly aluminum paint stripper according to claim 1, characterized in that: The specific steps include: Add alkaline substances into deionized water, stir and dissolve in a 60-70°C water bath at 50-60rpm to obtain alkaline solution, add accelerator catalyst, co-solvent, de-painting aid and surfactant into the alkaline solution, stir evenly to obtain an environmentally friendly aluminum paint stripper.

3. The method for preparing the environmentally friendly aluminum paint stripper according to claim 2, characterized in that: The preparation method of the promoting catalyst specifically comprises the following steps: S1. Evenly mix ferric chloride hexahydrate, ammonium acetate and sodium citrate dihydrate to obtain a reaction raw material, add the reaction raw material to ethylene glycol in an amount of 0.08-0.1 g / mL, stir in an oil bath, and obtain a reaction solution; S2, transferring the reaction solution obtained in S1 to an autoclave, heating for reaction, cooling to room temperature to obtain black powder, washing with anhydrous ethanol, and then vacuum drying to obtain nano-iron tetroxide; S3, uniformly mix zinc nitrate hexahydrate and 2-methylimidazole to obtain a mixture, add it to a methanol solution in an amount of 8-10 mg / mL, ultrasonically disperse for 10-15 minutes, then add the nano-iron tetroxide obtained in S2, stir in a water bath, centrifuge to obtain a precipitate, dry it, perform magnetic separation to remove non-magnetic and weakly magnetic components, wash with anhydrous ethanol, and vacuum dry it to obtain ZIF-8@Fe3O4; S4, adding ZIF-8@Fe3O4 obtained in S3 to a methanol solution at an addition amount of 20-30 mg / mL, then adding calcium chloride and barium chloride, stirring in a water bath, then adjusting the pH to 11-12 with 1 mol / L sodium hydroxide solution, slowly stirring for 2-3 h, centrifuging to obtain a precipitate and drying it, performing magnetic separation to remove non-magnetic and weakly magnetic components, washing with anhydrous ethanol, and vacuum drying to obtain Ba / Ca / ZIF-8@Fe3O4; S5. The precursor obtained in S4 is calcined for 100 minutes in a nitrogen atmosphere, cooled to room temperature, calcined for 15 minutes, and cooled to room temperature to obtain BaO / CaO / C@Fe3O4 as a promoting catalyst.

4. The method for preparing the environmentally friendly aluminum paint stripper according to claim 3, characterized in that: In S1, the oil bath stirring temperature is 165-175°C, the speed is 160-180 rpm, and the time is 60-80 min.

5. The method for preparing the environmentally friendly aluminum paint stripper according to claim 4, characterized in that: In S2, the heating reaction temperature is 200-220°C and the time is 14-16h.

6. The method for preparing the environmentally friendly aluminum paint stripper according to claim 5, characterized in that: In S3, the water bath stirring temperature is 65-75°C, the speed is 80-100 rpm, and the time is 25-35 min.

7. The method for preparing the environmentally friendly aluminum paint stripper according to claim 6, characterized in that: In S4, the water bath stirring temperature is 50-60°C, the speed is 60-80 rpm, and the time is 60-80 min.

8. The method for preparing the environmentally friendly aluminum paint stripper according to claim 7, characterized in that: In S5, the primary calcination temperature is 600-650°C, and the secondary calcination temperature is 950-1000°C.

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