Negative oxygen ion air purifying agent and preparation method thereof

Abstract

The invention relates to the technical field of air purifying materials, in particular to a negative oxygen ion air purifying agent and a preparation method thereof.The negative oxygen ion air purifying agent is prepared from ethyl cellulose, hydroxyethyl acrylate, citric acid activated bentonite, beta-cyclodextrine, neodymium-doped tourmaline powder, modified plant essential oil, propylene glycol and carboxymethylcellulose. Sodium polyaspartate and a pH buffer agent. According to the invention, through a triple technology of terpene-free essential oil selection, metal ion modification and beta-cyclodextrin coating, the problem of negative ion consumption of traditional essential oil is avoided, and the release amount and durability of negative oxygen ions are remarkably improved through a catalytic synergistic effect.

Description

Technical Field

[0001] The present invention relates to the technical field of air purification materials, in particular to a negative oxygen ion air purifier and a preparation method thereof. Background Art

[0002] In recent years, market demand for air purifiers has continued to grow, particularly those that release negative oxygen ions. These purifiers have attracted significant attention for their potential to improve indoor air quality and enhance human health. Negative oxygen ions have antibacterial, dust-removing, and odor-removing properties, but their stability is susceptible to environmental factors, particularly reactions with volatile organic compounds (VOCs) in the air, which can deplete the negative oxygen ions and reduce their effectiveness.

[0003] Currently, a variety of air purifiers utilize plant essential oils as fragrances and antibacterial ingredients. For example, Chinese invention patent publication number CN109701387B discloses a plant-based negative oxygen ion air purifier that utilizes tea tree oil, lemon oil, and perilla seed oil as its primary fragrance ingredients. However, these essential oils contain significant amounts of terpenes (such as limonene and α-pinene). These substances are chemically active and readily undergo oxidation reactions with negative oxygen ions, resulting in their consumption and reduced durability and effectiveness. Furthermore, terpenes can generate secondary pollutants (such as formaldehyde and ozone) when exposed to sunlight or high temperatures, further impacting indoor air quality.

[0004] Therefore, how to ensure that air purifiers have both aromatic and antibacterial properties without compromising the stability of negative oxygen ions has become a pressing technical challenge in this field. It is necessary to develop a new air purifier formula that can efficiently release negative oxygen ions while avoiding their consumption by essential oils, thereby improving the product's overall performance and durability. Summary of the Invention

[0005] The object of the present invention is to provide a negative oxygen ion air purifier and a preparation method thereof to solve the problems raised in the above background technology.

[0006] To achieve the above object, on the one hand, the present invention provides the following technical solution: a negative oxygen ion air purifier, comprising the following raw materials, by mass: 20-25 parts of ethyl cellulose, 10-15 parts of hydroxyethyl acrylate, 10-12 parts of citric acid-activated bentonite, 9-15 parts of β-cyclodextrin, 6-10 parts of neodymium-doped tourmaline powder, 6-10 parts of modified plant essential oil, 6-8 parts of propylene glycol, 1-2 parts of carboxymethyl cellulose, 1-2 parts of sodium polyaspartate, and 0.3-0.5 parts of a pH buffer;

[0007] The preparation method of the modified plant essential oil comprises the following steps: firstly, benzoin essential oil, tonka bean essential oil and Peru balsam essential oil are mixed in a mass ratio of 1:0.8-1.2:0.9-1.2 to obtain a mixed essential oil; then, 0.5-1.0g of magnesium lactate, 0.1-0.2g of zinc acetate and 0.05-0.08g of citric acid are dissolved in 1000ml of anhydrous ethanol to obtain a metal salt solution; then, the metal salt solution is added dropwise to 1000ml of the mixed essential oil at a stirring rate of 60-90rpm, and the mixture is heated in a water bath at 50-60°C for 15min. Finally, the mixture is filtered through a 0.22μm organic filter membrane to obtain the modified plant essential oil.

[0008] Optionally, the preparation method of the citric acid-activated bentonite includes the following steps: first mixing the bentonite with a 5wt% citric acid solution at a solid-liquid ratio of 1:8-9, ultrasonically treating the bentonite at a frequency of 40kHz and a power density of 50W / L at 80-84°C for 1h, then washing with deionized water until neutral and drying at 110-120°C, and finally calcining at 400-450°C for 2h.

[0009] Optionally, the preparation method of neodymium-doped tourmaline powder includes the following steps: first mixing tourmaline powder and neodymium nitrate in a mass ratio of 10:1 to 1.5, ball milling for 2 to 4 hours, and then calcining at 600 to 800°C for 4 hours to obtain a calcined product, and then air-grinding the calcined product to a particle size of ≤5μm.

[0010] Optionally, the pH buffer is a citric acid-sodium citrate buffer, and the pH of the pH buffer is 4.2.

[0011] On the other hand, the present invention also provides the following technical solution: a method for preparing a negative oxygen ion air purifier, comprising the following steps:

[0012] S1. Co-encapsulation: β-cyclodextrin and anhydrous ethanol were first mixed in a mass ratio of 1:1.5-2.0, stirred at 300-500 rpm for 10 min in a water bath at 50-55°C until completely wetted, then neodymium-doped tourmaline powder and modified plant essential oil were added, and homogenized at 1800-2200 rpm using a high-speed homogenizer for 15 min to obtain a suspension, and finally the suspension was placed in an atomizer and spray-dried at an air inlet temperature of 80°C and an air outlet temperature of 55-60°C to obtain a composite microcapsule powder;

[0013] S2. Prepare a substrate: dissolve ethyl cellulose and carboxymethyl cellulose in propylene glycol, stir at 600 rpm in a water bath at 60-65°C for 30-40 minutes until a transparent colloid is formed, then add hydroxyethyl acrylate and sodium polyaspartate, and continue stirring for 20-30 minutes until completely mixed to obtain a substrate solution;

[0014] S3. Solid phase dispersion: The composite microcapsule powder, citric acid-activated bentonite, and substrate solution are placed in a high-pressure homogenizer and circulated for 2 to 3 times at a pressure of 18 to 22 MPa, each time for 5 to 8 minutes, to obtain a mixed phase;

[0015] S4, aging: first add a pH buffer to the mixed phase for adjustment, stir and age it in a constant temperature water bath at 20-25° C. at a speed of 50-70 rpm for 3 hours, and finally degas for 15 minutes at a vacuum degree of -0.08-0.1 MPa to obtain the negative oxygen ion air purifier.

[0016] Optionally, in S1, the rotation speed of the atomizer is 20,000 to 25,000 rpm, and the atomization pressure is 0.15 to 0.25 MPa.

[0017] Optionally, in S3, the temperature in the high-pressure homogenizer is ≤45° C., and the high-pressure homogenizer is allowed to stand for 5 minutes after each cycle.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention increases the release of negative oxygen ions by adding a modified plant essential oil that does not contain terpenes. The magnesium lactate and zinc acetate introduced into the modified plant essential oil are beneficial for providing additional free electrons on the tourmaline surface, thereby enhancing the spontaneous polarization effect of the tourmaline surface and improving the negative ion generation efficiency.

[0020] 2. The present invention adopts the triple technology of selecting terpene-free essential oil + metal ion modification + β-cyclodextrin coating, which not only avoids the negative ion consumption problem of traditional essential oils, but also significantly improves the release amount and durability of negative oxygen ions through the catalytic synergistic effect. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] Example 1: The present invention provides a negative oxygen ion air purifier, comprising the following raw materials in parts by mass: 20 parts of ethyl cellulose, 10 parts of hydroxyethyl acrylate, 10 parts of citric acid activated bentonite, 9 parts of β-cyclodextrin, 6 parts of neodymium-doped tourmaline powder, 6 parts of modified plant essential oil, 6 parts of propylene glycol, 1 part of carboxymethyl cellulose, 1 part of sodium polyaspartate, and 0.3 parts of pH buffer.

[0023] The preparation method of the modified plant essential oil comprises the following steps: firstly, benzoin essential oil, tonka bean essential oil and Peru balsam essential oil are mixed in a mass ratio of 1:0.8:0.9 to obtain a mixed essential oil; then, 0.5 g of magnesium lactate, 0.1 g of zinc acetate and 0.05 g of citric acid are dissolved in 1000 mL of anhydrous ethanol to obtain a metal salt solution; then, the metal salt solution is added dropwise to 1000 mL of the mixed essential oil at a stirring rate of 60 rpm; and the mixture is heated in a water bath at 50°C for 15 minutes; and finally, the mixture is filtered through a 0.22 μm organic filter membrane to obtain the modified plant essential oil.

[0024] The preparation method of citric acid-activated bentonite includes the following steps: firstly, bentonite is mixed with 5wt% citric acid solution at a solid-liquid ratio of 1:8, ultrasonically treated at 80°C with a frequency of 40kHz and a power density of 50W / L for 1h, then washed with deionized water until neutral, dried at 110°C, and finally calcined at 400°C for 2h.

[0025] The preparation method of neodymium-doped tourmaline powder includes the following steps: firstly, tourmaline powder and neodymium nitrate are mixed in a mass ratio of 10:1, ball-milled for 2 hours, and then calcined at 600°C for 4 hours to obtain a calcined product, and then the calcined product is pulverized by air flow to a particle size of ≤5μm.

[0026] The preparation method of the negative oxygen ion air purifier comprises the following steps:

[0027] S1. Co-encapsulation: β-cyclodextrin and anhydrous ethanol were first mixed in a mass ratio of 1:1.5, stirred at 300 rpm for 10 min in a 50°C water bath until completely wetted, then neodymium-doped tourmaline powder and modified plant essential oil were added, and homogenized using a high-speed homogenizer at 1800 rpm for 15 min to obtain a suspension, and finally the suspension was placed in an atomizer and spray-dried at an inlet air temperature of 80°C and an outlet air temperature of 55°C to obtain a composite microcapsule powder, wherein the atomizer speed was 20,000 rpm and the atomization pressure was 0.15 MPa;

[0028] S2. Prepare a substrate: dissolve ethyl cellulose and carboxymethyl cellulose in propylene glycol, stir at 600 rpm in a water bath at 60-65°C for 30 minutes until a transparent colloid is formed, then add hydroxyethyl acrylate and sodium polyaspartate, and continue stirring for 20 minutes until completely mixed to obtain a substrate solution;

[0029] S3. Solid phase dispersion: The composite microcapsule powder, citric acid-activated bentonite, and substrate solution were placed in a high-pressure homogenizer and circulated twice at 18 MPa for 5 minutes each time to obtain a mixed phase. The temperature in the high-pressure homogenizer was ≤ 45°C, and the high-pressure homogenizer was allowed to stand for 5 minutes after each cycle.

[0030] S4. Ripening: first add a pH buffer to the mixed phase for adjustment, stir and ripen at a speed of 50 rpm in a constant temperature water bath at 20°C for 3 hours, and finally degas at a vacuum degree of -0.08 MPa for 15 minutes to obtain a negative oxygen ion air purifier.

[0031] Example 2: The present invention provides a negative oxygen ion air purifier, comprising the following raw materials in parts by mass: 25 parts of ethyl cellulose, 15 parts of hydroxyethyl acrylate, 12 parts of citric acid activated bentonite, 15 parts of β-cyclodextrin, 10 parts of neodymium-doped tourmaline powder, 10 parts of modified plant essential oil, 8 parts of propylene glycol, 2 parts of carboxymethyl cellulose, 2 parts of sodium polyaspartate, and 0.5 parts of pH buffer.

[0032] The preparation method of the modified plant essential oil comprises the following steps: firstly, benzoin essential oil, tonka bean essential oil and Peru balsam essential oil are mixed in a mass ratio of 1:1.2:1.2 to obtain a mixed essential oil; then, 1.0 g of magnesium lactate, 0.2 g of zinc acetate and 0.08 g of citric acid are dissolved in 1000 mL of anhydrous ethanol to obtain a metal salt solution; then, the metal salt solution is added dropwise to 1000 mL of the mixed essential oil at a stirring rate of 90 rpm; and the mixture is heated in a water bath at 60°C for 15 minutes. Finally, the mixture is filtered through a 0.22 μm organic filter membrane to obtain the modified plant essential oil.

[0033] The preparation method of citric acid-activated bentonite includes the following steps: firstly, bentonite is mixed with 5wt% citric acid solution at a solid-liquid ratio of 1:9, ultrasonically treated at 84°C with a frequency of 40kHz and a power density of 50W / L for 1 hour, then washed with deionized water until neutral, dried at 120°C, and finally calcined at 450°C for 2 hours.

[0034] The preparation method of neodymium-doped tourmaline powder includes the following steps: firstly, tourmaline powder and neodymium nitrate are mixed in a mass ratio of 10:1.5, ball-milled for 4 hours, and then calcined at 800°C for 4 hours to obtain a calcined product, and then the calcined product is pulverized by air flow to a particle size of ≤5μm.

[0035] The preparation method of the negative oxygen ion air purifier comprises the following steps:

[0036] S1. Co-encapsulation: β-cyclodextrin and anhydrous ethanol were first mixed in a mass ratio of 1:2.0, stirred at 500 rpm for 10 min in a 55°C water bath until completely wetted, then neodymium-doped tourmaline powder and modified plant essential oil were added, and homogenized using a high-speed homogenizer at 2200 rpm for 15 min to obtain a suspension, and finally the suspension was placed in an atomizer and spray-dried at an inlet air temperature of 80°C and an outlet air temperature of 60°C to obtain a composite microcapsule powder, wherein the atomizer speed was 25000 rpm and the atomization pressure was 0.25 MPa;

[0037] S2. Prepare a substrate; dissolve ethyl cellulose and carboxymethyl cellulose in propylene glycol, stir at 600 rpm in a 65°C water bath for 40 minutes until a transparent colloid is formed, then add hydroxyethyl acrylate and sodium polyaspartate, and continue stirring for 30 minutes until completely mixed to obtain a substrate solution;

[0038] S3. Solid phase dispersion: The composite microcapsule powder, citric acid-activated bentonite, and substrate solution were placed in a high-pressure homogenizer and circulated for 3 times at a pressure of 22 MPa, each for 8 minutes, to obtain a mixed phase. The temperature in the high-pressure homogenizer was ≤ 45°C, and the high-pressure homogenizer was allowed to stand for 5 minutes after each cycle.

[0039] S4. Ripening: first add a pH buffer to the mixed phase for adjustment, place in a constant temperature water bath at 25°C, stir at a speed of 70 rpm and ripen for 3 hours, and finally degas for 15 minutes at a vacuum degree of -0.1 MPa to obtain a negative oxygen ion air purifier.

[0040] Example 3: The present invention provides a negative oxygen ion air purifier, comprising the following raw materials in parts by mass: 22 parts of ethyl cellulose, 12 parts of hydroxyethyl acrylate, 11 parts of citric acid activated bentonite, 14 parts of β-cyclodextrin, 8 parts of neodymium-doped tourmaline powder, 8 parts of modified plant essential oil, 7 parts of propylene glycol, 1.5 parts of carboxymethyl cellulose, 1.5 parts of sodium polyaspartate, and 0.5 parts of pH buffer.

[0041] The preparation method of the modified plant essential oil comprises the following steps: firstly, benzoin essential oil, tonka bean essential oil and Peru balsam essential oil are mixed in a mass ratio of 1:1:1 to obtain a mixed essential oil; then, 0.75g of magnesium lactate, 0.15g of zinc acetate and 0.06g of citric acid are dissolved in 1000ml of anhydrous ethanol to obtain a metal salt solution; then, the metal salt solution is added dropwise to 1000ml of the mixed essential oil at a stirring rate of 75pm; and the mixture is heated in a water bath at 58°C for 15min. Finally, the mixture is filtered through a 0.22μm organic filter membrane to obtain the modified plant essential oil.

[0042] The preparation method of citric acid-activated bentonite includes the following steps: firstly, bentonite is mixed with 5wt% citric acid solution at a solid-liquid ratio of 1:9, ultrasonically treated at 82°C with a frequency of 40kHz and a power density of 50W / L for 1 hour, then washed with deionized water until neutral, dried at 115°C, and finally calcined at 435°C for 2 hours.

[0043] The preparation method of neodymium-doped tourmaline powder includes the following steps: firstly, tourmaline powder and neodymium nitrate are mixed in a mass ratio of 10:1.2, ball-milled for 3 hours, and then calcined at 720°C for 4 hours to obtain a calcined product, and then the calcined product is pulverized by air flow to a particle size of ≤5μm.

[0044] The preparation method of the negative oxygen ion air purifier comprises the following steps:

[0045] S1. Co-encapsulation: β-cyclodextrin and anhydrous ethanol were first mixed in a mass ratio of 1:1.8, stirred at 400 rpm for 10 min in a water bath at 82°C until completely wetted, then neodymium-doped tourmaline powder and modified plant essential oil were added, and homogenized at 2000 rpm for 15 min using a high-speed homogenizer to obtain a suspension, and finally the suspension was placed in an atomizer and spray-dried at an inlet air temperature of 80°C and an outlet air temperature of 58°C to obtain a composite microcapsule powder, wherein the atomizer speed was 24000 rpm and the atomization pressure was 0.20 MPa;

[0046] S2. Prepare a substrate: dissolve ethyl cellulose and carboxymethyl cellulose in propylene glycol, stir at 600 rpm in a 64°C water bath for 35 minutes until a transparent colloid is formed, then add hydroxyethyl acrylate and sodium polyaspartate, and continue stirring for 25 minutes until completely mixed to obtain a substrate solution;

[0047] S3. Solid phase dispersion: The composite microcapsule powder, citric acid-activated bentonite, and substrate solution were placed in a high-pressure homogenizer and circulated for 3 times at a pressure of 20 MPa, each for 8 minutes, to obtain a mixed phase. The temperature in the high-pressure homogenizer was ≤ 45°C, and the high-pressure homogenizer was allowed to stand for 5 minutes after each cycle.

[0048] S4. Ripening: first add a pH buffer to the mixed phase for adjustment, stir and ripen at a speed of 60 rpm in a constant temperature water bath at 22°C for 3 hours, and finally degas at a vacuum degree of -0.09 MPa for 15 minutes to obtain a negative oxygen ion air purifier.

[0049] Example 4: The present invention provides a negative oxygen ion air purifier, comprising the following raw materials in parts by mass: 24 parts of ethyl cellulose, 13 parts of hydroxyethyl acrylate, 11 parts of citric acid activated bentonite, 10 parts of β-cyclodextrin, 7 parts of neodymium-doped tourmaline powder, 7 parts of modified plant essential oil, 7 parts of propylene glycol, 1.5 parts of carboxymethyl cellulose, 1.5 parts of sodium polyaspartate, and 0.4 parts of pH buffer.

[0050] The preparation method of the modified plant essential oil comprises the following steps: firstly, benzoin essential oil, tonka bean essential oil and Peru balsam essential oil are mixed in a mass ratio of 1:1.2:1 to obtain a mixed essential oil; then, 0.8g of magnesium lactate, 0.05g of zinc acetate and 0.07g of citric acid are dissolved in 1000ml of anhydrous ethanol to obtain a metal salt solution; then, the metal salt solution is added dropwise to 1000ml of the mixed essential oil at a stirring rate of 80rpm, and the mixture is heated in a water bath at 55°C for 15min; and finally, the mixture is filtered through a 0.22μm organic filter membrane to obtain the modified plant essential oil.

[0051] The preparation method of citric acid-activated bentonite comprises the following steps: firstly, the bentonite is mixed with a 5wt% citric acid solution at a solid-liquid ratio of 1:8, and then ultrasonically treated at 82°C with a frequency of 40kHz and a power density of 50W / L for 1 hour, then washed with deionized water until neutral, dried at 118°C, and finally calcined at 480°C for 2 hours.

[0052] The preparation method of neodymium-doped tourmaline powder includes the following steps: firstly, tourmaline powder and neodymium nitrate are mixed in a mass ratio of 10:1.2, ball-milled for 3 hours, and then calcined at 650°C for 4 hours to obtain a calcined product, and then the calcined product is pulverized by air flow to a particle size of ≤5μm.

[0053] The preparation method of the negative oxygen ion air purifier comprises the following steps:

[0054] S1. Co-encapsulation: β-cyclodextrin and anhydrous ethanol were first mixed in a mass ratio of 1:1.8, stirred at 480 rpm for 10 min in a 54°C water bath until completely wetted, then neodymium-doped tourmaline powder and modified plant essential oil were added, and homogenized using a high-speed homogenizer at 2100 rpm for 15 min to obtain a suspension, and finally the suspension was placed in an atomizer and spray-dried at an inlet air temperature of 80°C and an outlet air temperature of 58°C to obtain a composite microcapsule powder, wherein the atomizer speed was 24000 rpm and the atomization pressure was 0.24 MPa;

[0055] S2. Prepare a substrate: dissolve ethyl cellulose and carboxymethyl cellulose in propylene glycol, stir at 600 rpm in a 63°C water bath for 32 minutes until a transparent colloid is formed, then add hydroxyethyl acrylate and sodium polyaspartate, and continue stirring for 28 minutes until completely mixed to obtain a substrate solution;

[0056] S3. Solid phase dispersion: The composite microcapsule powder, citric acid-activated bentonite, and substrate solution were placed in a high-pressure homogenizer and circulated for 2 cycles of 6 minutes each at 20 MPa to obtain a mixed phase. The temperature in the high-pressure homogenizer was ≤ 45°C, and the high-pressure homogenizer was allowed to stand for 5 minutes after each cycle.

[0057] S4. Ripening: first add a pH buffer to the mixed phase for adjustment, stir and ripen at a speed of 60 rpm in a constant temperature water bath at 22°C for 3 hours, and finally degas at a vacuum degree of -0.09 MPa for 15 minutes to obtain a negative oxygen ion air purifier.

[0058] In Examples 1-4, the pH buffer was a citric acid-sodium citrate buffer, and the pH of the pH buffer was 4.2. Benzoin essential oil, tonka bean essential oil, and Peru balsam essential oil are all terpene-free essential oils. Benzoin benzyl benzoate, tonka bean vanillin, and Peru balsam benzyl cinnamate are electron-rich aromatic compounds that can undergo a mild reduction reaction on the tourmaline surface, injecting additional electrons into lattice defects and neodymium-doped energy levels, increasing the surface electron density and enhancing the ionization efficiency of air molecules. Benzoin essential oil and tonka bean essential oil are both aromatic essential oils, while Peru balsam essential oil has antibacterial properties.

[0059] Comparative Example 1

[0060] The method is substantially the same as Example 3, except that no modified plant essential oil is used.

[0061] Comparative Example 1

[0062] Basically the same as Example 3, tea tree essential oil, lemon essential oil and perilla seed oil replaced the modified plant essential oil, wherein the mass ratio of tea tree essential oil, lemon essential oil and perilla seed oil was 3:1:2.

[0063] Test Example 1

[0064] Test content: Take the negative oxygen ion air purifier prepared in Examples 1 to 4 as the test group, and take the negative oxygen ion air purifier prepared in Comparative Examples 1 to 2 as the control group. Spray the test group and the control group on a 1m 3 In a sealed room, after being sealed for 24 hours, the indoor temperature of the sealed room was set to 0℃, 25℃ and 60℃, and the air ion concentration in the sealed room was measured using an electrometer, which is the amount of negative ions released. The results are recorded in Table 1.

[0065] Table 1

[0066] As can be seen from Table 1, the negative ion release of Examples 1 to 4 is much higher than that of Comparative Examples 1 to 2, the negative ion release of Comparative Example 1 is higher than that of Comparative Example 2, and compared with Comparative Examples 1 to 2, the ion release of Examples 1 to 4 at 60°C is much higher than that at 0°C, indicating that the selection of modified plant essential oils can significantly increase the negative ion release. It is speculated that after β-cyclodextrin and the modified plant essential oil form microcapsules, the volatilization rate of the modified essential oil is greatly suppressed, and the active sites on the surface of the neodymium-doped tourmaline powder are in contact with the modified plant essential oil for a long time. The magnesium lactate and zinc acetate introduced into the modified plant essential oil provide additional free electrons on the tourmaline surface, and Mg²⁺ and Zn²⁺ can act as electron acceptors to enhance the spontaneous polarization effect of the tourmaline surface and improve the negative ion generation efficiency.

[0067] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A negative oxygen ion air purifier, characterized in that: The composition is composed of the following raw materials in parts by mass: 20-25 parts of ethyl cellulose, 10-15 parts of hydroxyethyl acrylate, 10-12 parts of citric acid activated bentonite, 9-15 parts of β-cyclodextrin, 6-10 parts of neodymium-doped tourmaline powder, 6-10 parts of modified plant essential oil, 6-8 parts of propylene glycol, 1-2 parts of carboxymethyl cellulose, 1-2 parts of sodium polyaspartate, and 0.3-0.5 parts of pH buffer; The preparation method of the modified plant essential oil comprises the following steps: firstly, benzoin essential oil, tonka bean essential oil and Peru balsam essential oil are mixed in a mass ratio of 1:0.8-1.2:0.9-1.2 to obtain a mixed essential oil; then, 0.5-1.0g of magnesium lactate, 0.1-0.2g of zinc acetate and 0.05-0.08g of citric acid are dissolved in 1000ml of anhydrous ethanol to obtain a metal salt solution; then, the metal salt solution is added dropwise to 1000ml of the mixed essential oil at a stirring rate of 60-90rpm, and the mixture is heated in a water bath at 50-60°C for 15min. Finally, the mixture is filtered through a 0.22μm organic filter membrane to obtain the modified plant essential oil.

2. A negative oxygen ion air purifier according to claim 1, characterized in that, The preparation method of citric acid-activated bentonite comprises the following steps: firstly, mixing bentonite with a 5wt% citric acid solution at a solid-liquid ratio of 1:8-9, subjecting the bentonite to ultrasonic treatment at a frequency of 40kHz and a power density of 50W / L at 80-84°C for 1h, then washing the mixture with deionized water until neutral, drying the mixture at 110-120°C, and finally calcining the mixture at 400-450°C for 2h.

3. A negative oxygen ion air purifier according to claim 1, characterized in that: The preparation method of the neodymium-doped tourmaline powder comprises the following steps: firstly, mixing tourmaline powder and neodymium nitrate in a mass ratio of 10:1-1.5, ball milling for 2-4 hours, and then calcining at 600-800°C for 4 hours to obtain a calcined product, and then air-grinding the calcined product to a particle size of ≤5μm.

4. A negative oxygen ion air purifier according to claim 1, characterized in that: The pH buffer is a citric acid-sodium citrate buffer, and the pH of the pH buffer is 4.

2.

5. A method for preparing the negative oxygen ion air purifier according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Co-encapsulation: β-cyclodextrin and anhydrous ethanol were first mixed in a mass ratio of 1:1.5-2.0, stirred at 300-500 rpm for 10 min in a water bath at 50-55°C until completely wetted, then neodymium-doped tourmaline powder and modified plant essential oil were added, and homogenized at 1800-2200 rpm using a high-speed homogenizer for 15 min to obtain a suspension, and finally the suspension was placed in an atomizer and spray-dried at an air inlet temperature of 80°C and an air outlet temperature of 55-60°C to obtain a composite microcapsule powder; S2. Prepare a substrate: dissolve ethyl cellulose and carboxymethyl cellulose in propylene glycol, stir at 600 rpm in a water bath at 60-65°C for 30-40 minutes until a transparent colloid is formed, then add hydroxyethyl acrylate and sodium polyaspartate, and continue stirring for 20-30 minutes until completely mixed to obtain a substrate solution; S3. Solid phase dispersion: The composite microcapsule powder, citric acid-activated bentonite, and substrate solution are placed in a high-pressure homogenizer and circulated for 2 to 3 times at a pressure of 18 to 22 MPa, each time for 5 to 8 minutes, to obtain a mixed phase; S4, aging: first add a pH buffer to the mixed phase for adjustment, stir and age it in a constant temperature water bath at 20-25° C. at a speed of 50-70 rpm for 3 hours, and finally degas for 15 minutes at a vacuum degree of -0.08-0.1 MPa to obtain the negative oxygen ion air purifier.

6. The method for preparing a negative oxygen ion air purifier according to claim 5, characterized in that: In S1, the rotation speed of the atomizer is 20000-25000 rpm, and the atomization pressure is 0.15-0.25 MPa.

7. The method for preparing a negative oxygen ion air purifier according to claim 5, characterized in that: In S3, the temperature in the high-pressure homogenizer is ≤45°C, and the high-pressure homogenizer is left to stand for 5 minutes after each cycle.

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