Phosphorus-free and nitrogen-free cleaning agent as well as preparation method and application thereof

Abstract

The invention discloses a phosphorus-free and nitrogen-free cleaning agent as well as a preparation method and application thereof, and belongs to the field of cleaning agents. The phosphorus-free and nitrogen-free cleaning agent comprises the following raw materials in parts by mass: 6-9% of a bio-based chelating agent, 2-4% of sodium silicate, 3-6% of modified magnesium lithium silicate, 1-3% of lauroyl citrate, 3-6% of a nonionic surfactant and the balance of water, wherein the modified magnesium lithium silicate is subjected to benzamide intercalation modification treatment. The bio-based chelating agent can replace phosphate active ingredients in a traditional cleaning agent, the phosphorus-free and nitrogen-free cleaning agent is obtained, the eutrophication risk of a water body is eliminated from the source, electrostatic adsorption between greasy dirt and the surface of a magnetic material can be destroyed through the chelating effect of the bio-based chelating agent, emulsification and removal of the surfactant are facilitated, and the cleaning effect is good. The modified magnesium lithium silicate can capture stripped oil drop molecules, prevent re-attachment of oil stains and improve the cleaning effect, and can also be used as an adsorption site of the oil stains, reduce oil-water interfacial tension and improve the emulsification efficiency, so that the cleaning efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of cleaning agents, and in particular to a phosphorus-free and nitrogen-free cleaning agent, its preparation method, and its application. Background Technology

[0002] Magnetic materials are an important class of basic functional materials. Due to their excellent magnetic properties, they can be widely used in various fields such as energy, transportation, machinery, and medicine. Neodymium iron boron magnetic materials are among the strongest magnetic materials in the third generation of rare earth permanent magnet materials. They have the characteristics of high remanent magnetic induction, high coercivity, and high maximum magnetic energy product, which enables magnetic devices in high-tech industries to be more efficient, miniaturized, and lightweight.

[0003] However, due to the inherent characteristics of neodymium iron boron (NdFeB) magnetic materials, a large amount of dirt tends to adhere to their surface during processing. If this dirt is not cleaned, it will directly affect the performance and surface quality of the NdFeB magnetic materials. Furthermore, with their increasing applications across various industries, especially in the medical, automotive, and electronics sectors, the requirements for the surface quality and performance of NdFeB magnetic materials are becoming increasingly stringent.

[0004] Currently, the main cleaning methods used in the production and preparation of NdFeB magnetic materials include mechanical cleaning, chemical cleaning, and ultrasonic cleaning. Chemical cleaning primarily uses acids, alkalis, emulsifiers, dispersants, and organic degreasing agents to dissolve and remove rust, dirt, scale, and other contaminants adhering to the metal surface. Acidic cleaning agents, while effective, cannot completely remove surface dirt in short cleaning times, and prolonged cleaning can activate the magnetic material surface, making it more susceptible to corrosion. Alkaline cleaning agents, although less corrosive to magnetic materials, are mainly composed of phosphates. Phosphorus emissions can cause eutrophication of water bodies, posing a serious wastewater pollution problem. Furthermore, residual phosphates accumulate in the pores of the NdFeB magnetic material surface, forming electrolytes that accelerate electrochemical corrosion.

[0005] Therefore, there is an urgent need to develop a phosphorus-free, nitrogen-free, highly efficient, and environmentally friendly cleaning agent that can improve cleaning effectiveness while solving the problems of wastewater pollution and eutrophication of water bodies. Summary of the Invention

[0006] This invention provides a phosphorus-free and nitrogen-free cleaning agent, its preparation method, and its application, which can solve the problem of severe wastewater pollution and eutrophication caused by existing NdFeB magnetic material cleaning agents.

[0007] In a first aspect, the present invention provides a phosphorus-free and nitrogen-free cleaning agent, comprising the following raw materials in parts by weight: Bio-based chelating agents 6-9%; Sodium silicate 2-4%; Modified magnesium lithium silicate 3-6%; Lauroyl citrate 1-3%; Nonionic surfactants: 3-6%; Water balance; Modified lithium magnesium silicate was modified by benzamide intercalation.

[0008] Preferably, the bio-based chelating agent comprises a citric acid chelating agent and sodium gluconate in a mass ratio of 1:(0-1.5).

[0009] More preferably, the bio-based chelating agent comprises a citric acid chelating agent and sodium gluconate in a mass ratio of 1:(0.8 to 1.2).

[0010] Preferably, the citric acid chelating agent includes one or more combinations of sodium citrate, sodium monohydrogen citrate, and sodium dihydrogen citrate.

[0011] Preferably, the particle size of the modified magnesium lithium silicate is 20–80 μm.

[0012] Preferably, the nonionic surfactant includes one or more combinations of fatty alcohol polyoxyethylene ethers, alkyl glycosides and polysorbates.

[0013] By adopting the above technical solution, the main active ingredient of the present invention is a bio-based chelating agent. Compared with traditional strong acid and alkali cleaning agents, bio-based chelating agents are completely biodegradable, phosphorus-free and nitrogen-free, which can eliminate the risk of eutrophication of water bodies from the source.

[0014] Bio-based chelating agents include citric acid chelating agents and sodium gluconate. The carboxyl groups in citric acid chelating agents can strongly complex metal ions, preventing calcium and magnesium ions from forming insoluble soap scum with grease, thus improving the stability of the detergent in water. Its chelating effect can break the electrostatic adsorption between oil and the surface of magnetic materials, dispersing oil droplets into tiny particles, which are easier for surfactants to emulsify and remove. Furthermore, citric acid chelating agents are small molecule compounds, and their small molecule characteristics can help penetrate into the pores of NdFeB magnetic materials, dissolving deep-seated oil and achieving deep cleaning.

[0015] However, citric acid chelating agents generally have poor thermal stability, and their chelating ability drops sharply at high temperatures. While they can maintain a certain chelating ability at low temperatures, their degreasing kinetics are slow, affecting cleaning efficiency. To solve this problem, sodium gluconate can be added to the mixture with citric acid chelating agents. Sodium gluconate has good thermal stability and can maintain excellent chelating ability even at high temperatures, which can compensate for the high-temperature failure problem of citric acid chelating agents.

[0016] The gluconate ions in sodium gluconate preferentially bind to calcium and magnesium ions in water, preventing calcium soap deposition that could clog the surface pores of NdFeB magnetic materials. This avoids a decrease in surface adhesion after cleaning. Furthermore, as a polyhydroxy acid corrosion inhibitor, sodium gluconate can synergistically form a passivation protection on the surface of NdFeB magnetic materials with sodium silicate, significantly reducing the corrosion rate of the magnetic material matrix and blocking electrochemical corrosion.

[0017] Furthermore, the cleaning agent of the present invention also contains modified lithium magnesium silicate. Lithium magnesium silicate has a unique layered structure. The bio-based chelating agent preferentially chelates active metal ions, cutting off the interfacial bond between oil stains and the surface of neodymium iron boron magnetic materials. Lithium magnesium silicate adsorbs residual calcium and magnesium ions through the interlayer ion exchange capacity, deeply purifying while preventing soap scum formation, and can capture separated oil stains, thus improving the cleaning effect.

[0018] However, the interlayer spacing of unmodified lithium magnesium silicate is small, making it difficult to accommodate large molecular oil contaminants. Therefore, lithium magnesium silicate is subjected to intercalation modification. Benzamide is used for intercalation modification. Benzamide can form a hydrogen bond network between the negative ions between the layers of lithium magnesium silicate through amide bonds, thereby increasing the interlayer spacing of lithium magnesium silicate and enabling it to accommodate sufficient large molecular oil contaminants.

[0019] Intercalation modification can release more interlayer sites, and the amide bonds in benzamide can also provide additional negative potential sites, thereby enhancing the targeted adsorption capacity for metal ions. The contained phenyl groups can also provide a certain degree of hydrophobicity, which can combine with the hydrophilic interlayer structure of lithium magnesium silicate to form an amphiphilic interface, thereby improving the emulsification efficiency of oil stains and also improving the thermal stability of lithium magnesium silicate, maintaining structural stability.

[0020] By compounding sodium gluconate and combining it with intercalated modified lithium magnesium silicate, the heat sensitivity defect of citric acid chelating agents can be solved. It can also improve the cleaning ability of the detergent by synergistically chelating and capturing separated oil molecules, significantly improving the degreasing rate of the detergent, while not damaging the surface of the neodymium iron boron magnetic material, thus ensuring the performance and quality of the magnetic material.

[0021] Preferably, the raw materials for modified lithium magnesium silicate include lithium magnesium silicate and benzamide in a mass ratio of 1:(0.2-0.4).

[0022] Preferably, the modified magnesium lithium silicate is prepared according to the following method: Lithium magnesium silicate is dispersed in water, the pH of the solution is adjusted to 6-7, the temperature is raised to 35-40℃, and the mixture is stirred and activated for 30-60 minutes to obtain a pre-reaction solution. The benzamide solution was added dropwise to the pre-reaction solution, and the mixture was stirred at 80-85°C for 2-3 hours. Finally, the modified magnesium lithium silicate was obtained by filtration, washing, drying and grinding.

[0023] More preferably, the benzamide solution has a mass fraction of 15-20%.

[0024] By adopting the above technical solution, benzamide enters the interlayer of lithium magnesium silicate through liquid-phase intercalation. The amide bonds contained in the molecule can combine with the negative charge between the lithium magnesium silicate layers through electrostatic attraction and hydrogen bonding, thereby expanding the interlayer spacing of lithium magnesium silicate. Then, through mechanical grinding, the porosity of the modified lithium magnesium silicate can be further increased, thereby increasing the space for accommodating oil molecules.

[0025] The phenyl group in benzamide provides a certain degree of hydrophobicity to the modified magnesium lithium silicate, serving as an adsorption site for oil stains. Simultaneously, it forms an amphiphilic interface with the hydrophilic nature of bio-based chelating agents, thereby reducing oil-water surface tension, improving emulsification efficiency, and ultimately enhancing cleaning efficiency. Furthermore, it can synergistically form a composite protective layer on the surface of magnetic materials with sodium gluconate and sodium silicate, preventing further oxidation and corrosion of the magnetic materials.

[0026] Compared to other intercalation modification methods, the modified lithium magnesium silicate obtained by benzamide intercalation modification has good structural stability and adsorption stability, which is beneficial to improving the cleaning efficiency of bio-based chelating agents. Furthermore, the magnesium silicate modified by benzamide can form a three-dimensional network framework with lauroyl citrate and nonionic surfactants in the system, which can effectively prevent particle sedimentation, maintain the stability of the cleaning agent, and help to act uniformly on the surface of magnetic materials.

[0027] Preferably, the raw materials for lauroyl citrate include citric acid and lauroyl chloride in a mass ratio of 1:(0.8 to 0.95).

[0028] More preferably, lauroyl citrate is prepared by the following method: Citric acid is added to acetone, the temperature is raised to 35-45°C, and the mixture is stirred to dissolve. Lauroyl chloride is added dropwise at a rate of 4-6 g / min under reflux, and the reaction is carried out for 3-4 h. Then, the mixture is washed and dried under reduced pressure at 60-65°C to obtain lauroyl citrate.

[0029] By adopting the above technical solution, lauroyl citrate is also added to the detergent. It is formed by esterification of hydrophilic citric acid groups and hydrophobic lauryl segments. Its hydrophobic chain can be quickly adsorbed onto the oil stain surface, and its hydrophilic group can be oriented in the aqueous phase, thereby significantly reducing the oil-water interfacial tension, enhancing the emulsification and stripping ability, dispersing large oil droplets into microdroplets, creating a larger contact interface for the subsequent chelating effect of bio-based chelating agents, and improving the degreasing effect of the detergent.

[0030] Furthermore, the citric acid groups in lauroyl citrate can interact with the bio-based chelating agents in the system to form a mixed chelating network, thereby enhancing the ability to capture metal ions and compensating for the insufficient alkalinity leading to grease decomposition defects caused by the addition of citric acid chelating agents alone, thus enhancing the oil-removing ability of the detergent. Further, the composite micelles formed between the two will encapsulate the separated oil droplets and prevent oil from re-adhering to the surface of the magnetic material through electrostatic repulsion.

[0031] By combining bio-based chelating agents and lauroyl citrate, the emulsifying ability is utilized to improve the oil removal rate and reduce the adhesion strength of oil stains, thereby reducing oil residue on the surface of magnetic materials, including surface pores, and improving the cleaning effect of the detergent.

[0032] Secondly, the present invention provides a method for preparing a phosphorus-free and nitrogen-free cleaning agent, comprising the following process steps: S101. Add bio-based chelating agent and lauroyl citrate to water, stir evenly, then add modified magnesium lithium silicate, and continue stirring to obtain a premixed solution; S102. Add sodium silicate and nonionic surfactant to the premixed solution in sequence, and stir evenly to obtain a phosphorus-free and nitrogen-free cleaning agent.

[0033] Thirdly, the present invention provides an application of a phosphorus-free and nitrogen-free cleaning agent, which is applied to the surface cleaning of materials including neodymium iron boron magnetic materials; The cleaning steps include the following: S201. Ultrasonic water washing of neodymium iron boron magnetic materials; S202. The washed NdFeB magnetic material is immersed in a phosphorus-free and nitrogen-free cleaning agent diluted with water, the temperature is raised to 35-45℃, ultrasonically vibrated, and finally washed and dried to obtain the final product.

[0034] More preferably, the dilution ratio with water is 15 to 20.

[0035] The beneficial effects of this invention are: 1. The phosphorus-free and nitrogen-free cleaning agent of this invention uses a bio-based chelating agent to replace the phosphate-based active ingredients in traditional cleaning agents, thereby obtaining a phosphorus-free and nitrogen-free cleaning agent and eliminating the risk of eutrophication of water bodies at the source. The bio-based chelating agent includes citric acid chelating agents and sodium gluconate. Their chelating action can break the electrostatic adsorption between oil stains and the surface of magnetic materials, dispersing oil droplets into tiny particles, facilitating emulsification and removal by surfactants. Furthermore, the citric acid chelating agent is a small molecule compound that can penetrate into the pores of the NdFeB magnetic material surface, dissolving deep-seated oil stains and achieving deep cleaning.

[0036] 2. The phosphorus-free and nitrogen-free cleaning agent of the present invention also contains modified lithium magnesium silicate. The lithium magnesium silicate modified by benzamide intercalation can, on the one hand, expand the interlayer spacing of lithium magnesium silicate, increase the spatial capacity for capturing oil molecules, prevent the re-adhesion of oil, and improve the cleaning effect; on the other hand, the phenyl group in benzamide can provide a certain degree of hydrophobicity, which can serve as an adsorption site for oil. It forms an amphiphilic interface with the hydrophilicity of the bio-based chelating agent, thereby reducing the oil-water interfacial tension, improving emulsification efficiency, and thus improving cleaning efficiency. Detailed Implementation

[0037] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0038] Preparation Example

[0039] Preparation Example 1: A modified magnesium lithium silicate was prepared according to the following method: 10g of lithium magnesium silicate was dispersed in water to prepare a 5% (w / w) solution. The pH of the solution was adjusted to 6.5, the temperature was raised to 40℃, and the solution was stirred and activated for 40 min to obtain a pre-reaction solution. A 20% benzamide solution (3g of benzamide) was added dropwise to the pre-reaction solution, and the mixture was stirred at 80°C for 3 hours. Finally, after filtration, washing, drying and grinding, the modified magnesium lithium silicate was obtained by passing the mixture through a 160-mesh sieve.

[0040] Preparation Example 2, a modified magnesium lithium silicate, differs from Preparation Example 1 only in that the amount of benzamide added is 2g.

[0041] Preparation Example 3, a modified magnesium lithium silicate, differs from Preparation Example 1 only in that the amount of benzamide added is 4g.

[0042] Preparation Example 4, a modified magnesium lithium silicate, differs from Preparation Example 1 only in that the amount of benzamide added is 6g.

[0043] Preparation Example 5, a modified magnesium lithium silicate, differs from Preparation Example 1 only in that an equal amount of sodium dodecylbenzenesulfonate is used to replace benzamide.

[0044] Example

[0045] Example 1: A phosphorus-free and nitrogen-free cleaning agent was prepared according to the following method: S101. Add 8g of bio-based chelating agent (sodium citrate monohydrogen chelating agent) and 2g of lauroyl citrate to water, stir evenly, then add 4g of modified lithium magnesium silicate prepared in Preparation Example 1, and continue stirring to obtain a premixed solution. Lauroyl citrate was prepared by the following method: Add 10g of citric acid to acetone, heat to 40℃, stir to dissolve, and add 9g of lauroyl chloride dropwise at a rate of 4g / min under reflux. React for 4h; then wash and dry under reduced pressure at 60℃ to obtain lauroyl citrate.

[0046] S102. Add 3g of sodium silicate and 5g of alkyl glycoside to the premixed solution in sequence, stir well to obtain a phosphorus-free and nitrogen-free cleaning agent; The total mass of the phosphorus-free and nitrogen-free cleaning agent obtained was 100g, with water as the remainder.

[0047] Example 2, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 1 only in that a bio-based chelating agent obtained by mixing sodium citrate and sodium gluconate in an equal mass ratio of 1:1 is used to replace sodium citrate monohydrogen in Example 1.

[0048] Examples 3 and 4 describe a phosphorus-free and nitrogen-free cleaning agent. The only difference between these two examples and Example 2 is the adjustment of the raw material ratios, as shown in Table 1. Table 1. Raw material formulas for Examples 2 to 4

[0049] In both Examples 3 and 4, the modified lithium magnesium silicate prepared in Example 1 and the lauroyl citrate prepared in Example 1 were used. The bio-based chelating agent used in Example 2 was obtained by mixing sodium citrate and sodium gluconate in a mass ratio of 1:0.5; the bio-based chelating agent used in Example 3 was obtained by mixing sodium citrate and sodium gluconate in a mass ratio of 1:1.5.

[0050] Example 5, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 2 only in that an equal amount of modified magnesium lithium silicate prepared in Example 2 is used to replace the modified magnesium lithium silicate prepared in Example 1.

[0051] Example 6, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 2 only in that an equal amount of modified magnesium lithium silicate prepared in Preparation Example 3 is used instead of the modified magnesium lithium silicate prepared in Preparation Example 1.

[0052] Example 7, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 2 only in that an equal amount of modified magnesium lithium silicate prepared in Preparation Example 4 is used instead of the modified magnesium lithium silicate prepared in Preparation Example 1.

[0053] Comparative Example

[0054] Comparative Example 1, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 2 only in that the amount of modified magnesium lithium silicate added in Preparation Example 1 is 1g.

[0055] Comparative Example 2, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 2 only in that the amount of modified magnesium lithium silicate added in Preparation Example 1 is 8g.

[0056] Comparative Example 3, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 2 only in that an equal amount of modified magnesium lithium silicate prepared in Preparation Example 5 is used instead of the modified magnesium lithium silicate prepared in Preparation Example 1.

[0057] Comparative Example 4, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 2 only in that an equal amount of unmodified lithium magnesium silicate is used to replace the modified lithium magnesium silicate prepared in Preparation Example 1.

[0058] Comparative Example 5, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 2 only in that the modified lithium magnesium silicate prepared in Preparation Example 1 is not added.

[0059] Comparative Example 6, a phosphorus-free and nitrogen-free cleaning agent, differs from Example 2 only in that lauroyl citrate is not added.

[0060] Performance testing

[0061] The phosphorus-free and nitrogen-free cleaning agents obtained in the examples and comparative examples were used to clean the neodymium iron boron magnetic materials, specifically including the following steps: S201. The neodymium iron boron magnetic material is ultrasonically washed with water. The ultrasonic washing power is 1500w and the washing time is 5min. S202. The washed NdFeB magnetic material is immersed in a phosphorus-free and nitrogen-free cleaning agent diluted 20 times with water, the temperature is raised to 40°C, and ultrasonically vibrated at a power of 2000W for 5 minutes. Finally, it is washed with water and dried to obtain the final product.

[0062] The white paper quantitative detection method was adopted. The cleaned NdFeB magnetic material was rubbed with white paper, and the weight difference of the magnetic material and white paper before and after rubbing was measured. The oil removal rate and black ash residue of the magnetic material before and after cleaning were tested.

[0063] The experimental results are shown in Table 2: Table 2 Performance test results

[0064] According to Table 2, combined with Examples 1 and 2, it can be seen that the cleaning effect of Example 1 is lower than that of Example 2. The reason is that the bio-based chelating agent in Example 1 is only a citric acid chelating agent, which has limited stability and slow degreasing kinetics, resulting in low cleaning efficiency. In contrast, Example 2 also contains sodium gluconate, which can make up for the defects of adding citric acid chelating agent alone, improve the overall chelating ability, and also work with sodium silicate to form a passivation layer on the surface of the cleaned NdFeB magnetic material, reducing dirt residue.

[0065] Combining Example 2 and Comparative Example 3, it can be seen that the cleaning effect of Comparative Example 3 is significantly lower than that of Example 2. The reason is that sodium dodecylbenzenesulfonate was used to modify lithium magnesium silicate in Comparative Example 3. Although it can also expand the interlayer spacing, the binding force between sodium dodecylbenzenesulfonate and lithium magnesium silicate is reduced compared to phenylamide, and the stability is reduced. Moreover, benzamide can also synergize with bio-based chelating agents to improve the overall chelating effect and improve the emulsification efficiency of oil stains. The synergistic effect of lithium magnesium silicate obtained by using other intercalation modifiers is reduced, and the cleaning effect is reduced.

[0066] Based on Examples 2, 4, and 5, it can be seen that the cleaning effect of Comparative Examples 4 and 5 is significantly lower than that of Example 2. The reason is that Comparative Example 4 uses unmodified lithium magnesium silicate, which has a small interlayer spacing and cannot accommodate a large number of oil droplets peeled off from the surface of the neodymium iron boron magnetic material, which easily leads to the re-adhesion of oil droplets and dirt. In Comparative Example 5, no lithium magnesium silicate is added, so the ability to capture oil droplets is reduced, resulting in a decrease in cleaning effect.

[0067] Combining Example 2 and Comparative Example 6, it can be seen that the cleaning effect of Comparative Example 6 is significantly reduced compared to Example 2. The reason is that Comparative Example 6 does not contain lauroyl citrate, which reduces the emulsification and stripping ability and the chelation synergy with the bio-based chelating agent. It is unable to encapsulate and separate the stripped oil droplets. Furthermore, the capacity of the modified magnesium lithium silicate is limited, which leads to a decrease in the cleaning effect of the obtained cleaning agent.

[0068] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A phosphorus-free and nitrogen-free cleaning agent, characterized in that, The raw materials include the following parts by weight: Bio-based chelating agents 6-9%; Sodium silicate 2-4%; Modified magnesium lithium silicate 3-6%; Lauroyl citrate 1-3%; Nonionic surfactants: 3-6%; Water balance; The modified magnesium lithium silicate was modified by benzamide intercalation.

2. The phosphorus-free and nitrogen-free cleaning agent according to claim 1, characterized in that, The bio-based chelating agent comprises a citric acid chelating agent and sodium gluconate in a mass ratio of 1:(0-1.5).

3. The phosphorus-free and nitrogen-free cleaning agent according to claim 2, characterized in that, The citric acid chelating agent includes one or more combinations of sodium citrate, sodium monohydrogen citrate, and sodium dihydrogen citrate.

4. The phosphorus-free and nitrogen-free cleaning agent according to claim 1, characterized in that, The modified magnesium lithium silicate raw materials include magnesium lithium silicate and benzamide in a mass ratio of 1:(0.2-0.4).

5. The phosphorus-free and nitrogen-free cleaning agent according to claim 4, characterized in that, The modified lithium magnesium silicate was prepared according to the following method: Lithium magnesium silicate is dispersed in water, the pH of the solution is adjusted to 6-7, the temperature is raised to 35-40℃, and the mixture is stirred and activated for 30-60 minutes to obtain a pre-reaction solution. The benzamide solution was added dropwise to the pre-reaction solution, and the mixture was stirred at 80-85°C for 2-3 hours. Finally, the modified magnesium lithium silicate was obtained by filtration, washing, drying and grinding.

6. The phosphorus-free and nitrogen-free cleaning agent according to claim 1, characterized in that, The modified magnesium lithium silicate has a particle size of 20–80 μm.

7. The phosphorus-free and nitrogen-free cleaning agent according to claim 1, characterized in that, The raw materials for the lauroyl citrate include citric acid and lauroyl chloride in a mass ratio of 1:(0.8 to 0.95).

8. The phosphorus-free and nitrogen-free cleaning agent according to claim 1, characterized in that, The nonionic surfactant includes one or more combinations of fatty alcohol polyoxyethylene ethers, alkyl glycosides, and polysorbates.

9. A method for preparing a phosphorus-free and nitrogen-free cleaning agent according to any one of claims 1 to 8, characterized in that, The process includes the following steps: S101. Add bio-based chelating agent and lauroyl citrate to water, stir evenly, then add modified magnesium lithium silicate, and continue stirring to obtain a premixed solution; S102. Add sodium silicate and nonionic surfactant to the premixed solution in sequence, and stir evenly to obtain a phosphorus-free and nitrogen-free cleaning agent.

10. The application of a phosphorus-free and nitrogen-free cleaning agent according to any one of claims 1 to 8, characterized in that, The phosphorus-free and nitrogen-free cleaning agent is used for surface cleaning, including neodymium iron boron magnetic materials; The cleaning steps include the following: S201. Ultrasonic water washing of neodymium iron boron magnetic materials; S202. The washed NdFeB magnetic material is immersed in a phosphorus-free and nitrogen-free cleaning agent diluted with water, the temperature is raised to 35-45℃, ultrasonically vibrated, and finally washed and dried to obtain the final product.

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