Low-odor high-purity zinc stearate and preparation method thereof

Abstract

The invention provides low-odor high-purity zinc stearate and a preparation method thereof.The preparation method comprises the following steps that S1, stearic acid and zinc oxide react under the action of an acid-photocatalysis composite catalyst in a liquid acid environment, the acid-photocatalysis composite catalyst is recycled, filtered and separated, solid matter is taken, and a zinc stearate crude product is obtained; s2, the zinc stearate crude product is stirred and dissolved in absolute ethyl alcohol, an adsorbent is added, after adsorption, the adsorbent is separated and filtered out, filtrate is taken, and zinc stearate refined liquid is obtained; and S3, cooling the zinc stearate refined liquid, separating out crystals, filtering, and taking the crystals to obtain the low-odor high-purity zinc stearate. Impurity molecules in the zinc stearate product can be effectively reduced, so that the purity of the zinc stearate product is improved, the peculiar smell is reduced, and the application of the zinc stearate product in the fields of medicines and cosmetics is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of zinc stearate, and in particular to low-odor high-purity zinc stearate and a preparation method thereof. Background Art

[0002] Zinc stearate is a metallic soap compound formed by the combination of stearic acid and zinc. It appears as a white powder at room temperature and exhibits strong hydrophobicity, lubricity, and thermal stability. It is widely used in both industrial and consumer products. In the pharmaceutical industry, zinc stearate is primarily used as a lubricant and release agent for tablets and capsules, significantly improving the flowability and tableting efficiency of drug powders. Its hydrophobicity also allows it to be used in drug coatings to enhance drug stability. In cosmetics, zinc stearate is often added to products such as foundation, loose powder, and eye shadow to improve makeup longevity.

[0003] In the prior art, zinc stearate is generally prepared using a double decomposition method or a direct method. The double decomposition method involves ion-exchanging sodium stearate with a zinc salt to produce zinc stearate, followed by precipitation, washing, filtering, and drying to obtain the zinc stearate product. The direct method, on the other hand, involves heating stearic acid with zinc oxide / zinc hydroxide to produce zinc stearate. However, these methods are difficult to achieve complete reaction, resulting in limited purity of the zinc stearate in the product and the presence of impurities and odor. This significantly restricts the application of zinc stearate in the fields of medicine and cosmetics. Therefore, there is an urgent need to provide a solution to address these issues. Summary of the Invention

[0004] In view of this, the present invention provides a low-odor, high-purity zinc stearate and a preparation method thereof, which can effectively reduce impurity molecules in the zinc stearate product, thereby facilitating the improvement of the purity of the zinc stearate product and reducing the odor, and is conducive to the application of the zinc stearate product in the fields of medicine and cosmetics.

[0005] The technical solution of the present invention is achieved as follows:

[0006] A method for preparing low-odor, high-purity zinc stearate comprises the following steps:

[0007] S1. reacting stearic acid and zinc oxide in a liquid acidic environment under the action of an acid-photocatalytic composite catalyst, recovering the acid-photocatalytic composite catalyst and separating it by filtration, and taking a solid to obtain a crude zinc stearate product;

[0008] S2, stirring and dissolving the crude zinc stearate product in anhydrous ethanol and adding an adsorbent, separating and filtering out the adsorbent after adsorption, and taking the filtrate to obtain a refined zinc stearate solution;

[0009] S3. Cooling the refined zinc stearate solution to precipitate crystals, filtering and taking the crystals to obtain low-odor high-purity zinc stearate.

[0010] Furthermore, the molar ratio of stearic acid to zinc oxide in S1 is 2:(1.5-2), the pH of the acidic environment is 2.0-5.0, and the stearic acid and zinc oxide react at 70-80° C. for 1-3 hours under the action of an acid-photocatalytic composite catalyst.

[0011] Furthermore, the mass ratio of the acid-photocatalytic composite catalyst to zinc oxide in S1 is (0.5-5):100, and the reaction is carried out under a UV lamp, an inert atmosphere and an ultrasonic environment.

[0012] Furthermore, the ultrasonic power is 200-500W, the ultrasonic frequency is 20-40kHz, the violet light wavelength is 365nm, the light intensity is 10-50mW / cm2, and the inert atmosphere is nitrogen or argon atmosphere.

[0013] Furthermore, the acid-photocatalytic composite catalyst is prepared by the following method: dissolving ferric chloride hexahydrate and ferrous chloride tetrahydrate in deionized water in a molar ratio of 2:1, adding ammonia water to react for 25-35 minutes under a nitrogen atmosphere at 75-85°C, and obtaining ferroferric oxide particles after magnetic separation and washing; dispersing the ferroferric oxide particles in a 75-85wt% ethanol aqueous solution, adding ammonia water and ethyl orthosilicate, the ferroferric oxide particles, ammonia water, and ethyl orthosilicate mass volume ratio g / mL is 1:(0.05-0.15):(0.2-0.5), reacting at 38-42°C for 5.5-6.5 hours, forming a silicon dioxide protective layer on the surface of the ferroferric oxide particles, and then dispersing the above-mentioned ferroferric oxide particles in toluene, adding (3-mercaptopropyl)trimethoxysilane, the ferroferric oxide particles, (3-mercaptopropyl)trimethoxysilane, The method comprises the following steps: dispersing the sulfonic acid group-modified ferrosoferric oxide particles in anhydrous ethanol, adding tetrabutyl titanate, wherein the mass volume ratio of the sulfonic acid group-modified ferrosoferric oxide particles is 1:(0.1-0.3) in g / mL, and refluxing the product at 75-85° C. for 11-13 hours. The refluxed product is immersed in 28-32wt% hydrogen peroxide and oxidized at 55-65° C. for 5.5-6.5 hours to obtain sulfonic acid group-modified ferrosoferric oxide particles. The sulfonic acid group-modified ferrosoferric oxide particles are dispersed in anhydrous ethanol, and tetrabutyl titanate is added. The mass volume ratio of the sulfonic acid group-modified ferrosoferric oxide particles to the tetrabutyl titanate is 1:(0.5-1.0) in g / mL. The product is ultrasonically treated for 25-35 minutes under the conditions of an ultrasonic power of 200-400W and an ultrasonic frequency of 40-60kHz. A 1wt% hydrochloric acid solution is slowly added dropwise, and the product is hydrolyzed at 38-42° C. for 2.8-3.2 hours. The product is then subjected to magnetic separation and washing, and calcined at 380-420° C. for 1.9-2.1 hours to obtain an acid-photocatalytic composite catalyst.

[0014] Furthermore, the crude zinc stearate product in S2 is added to anhydrous ethanol at 65-75°C at a solid-liquid ratio of 0.08-0.12 g / mL and stirred for dissolution. Subsequently, the adsorbent is added and adsorbed at 65-75°C, an ultrasonic power of 200-400 W, and an ultrasonic frequency of 40-60 kHz for 2-3 hours. The S3 is cooled to 10-5°C at a rate of 1-5°C / min.

[0015] Furthermore, the adsorbent is prepared by the following method: diatomaceous earth with a solid-liquid ratio of 0.06-0.08 g / mL is placed in a 10-15wt% hydrochloric acid solution at 40-50°C and soaked for 80-120 minutes, the diatomaceous earth is separated and washed with deionized water to obtain an activated matrix; the activated matrix is ​​immersed in an aluminum-containing solution and separated and calcined to obtain an activated intermediate; then, amino-modified graphene quantum dots are dispersed in ethanol at a ratio of 0.5-1wt% and the activated intermediate is added, the mass ratio of the amino-modified graphene quantum dots to the activated intermediate is 1:80-100, and ultrasonic treatment is performed for 25-35 minutes under ultrasonic power of 150-250W and ultrasonic frequency of 20-40kHz to obtain a graphene quantum dot-loaded intermediate; then, the graphene quantum dot-loaded intermediate is immersed in a silane solution and separated and dried to obtain the adsorbent.

[0016] Furthermore, one of aluminum nitrate, aluminum chloride, and aluminum sulfate is dissolved in the aluminum-containing solution, the mass ratio of the activated matrix to the aluminum ions in the aluminum-containing solution is 1:(0.2-0.3), the activated matrix is ​​ultrasonically immersed in the aluminum-containing solution at 80-100°C, separated, and calcined at 400-500°C to obtain an activated intermediate, which is ultrasonically immersed in the aluminum-containing solution for 10-14 hours. During the ultrasonic immersion, the ultrasonic power is 200-300W and the ultrasonic frequency is 40-60kHz.

[0017] Furthermore, the silane solute in the silane solution includes one of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane, and the graphene quantum dot-loaded intermediate is immersed in the silane solution at 40-50°C, immersed in the silane solution for 40-50 minutes, separated, and dried at 80-100°C to obtain an adsorbent.

[0018] Furthermore, low-odor and high-purity zinc stearate is obtained by the above preparation method.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. By carrying out the reaction under the catalytic action of an acid-photocatalytic composite catalyst, it is beneficial to increase the reaction of stearic acid and zinc oxide to form zinc stearate, thereby increasing the yield of zinc stearate;

[0021] 2. By using hot ethanol to dissolve the crude zinc stearate product, the solubility of zinc stearate in hot ethanol can be used to separate the residual zinc oxide in the crude zinc stearate product, and zinc stearate can be precipitated during the subsequent cooling process;

[0022] 3. Adsorption treatment using an adsorbent can effectively reduce the residual stearic acid or by-product molecules in zinc stearate, and can adsorb odor molecules, thereby effectively reducing the unpleasant odor of zinc stearate products, which is beneficial to the application of zinc stearate products in the fields of medicine and cosmetics. DETAILED DESCRIPTION

[0023] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0024] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0025] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0026] Example 1

[0027] A method for preparing low-odor, high-purity zinc stearate comprises the following steps:

[0028] S1. In a liquid acidic environment with a pH of 2.0, stearic acid and zinc oxide are reacted in a molar ratio of 2:1.5 at 70°C under a violet lamp and an inert atmosphere under an ultrasonic environment for 3 hours. The mass ratio of the acid-photocatalytic composite catalyst to zinc oxide is 0.5:100. The acid-photocatalytic composite catalyst is recovered and filtered to separate the solids to obtain a crude zinc stearate product. The ultrasonic power is 200W, the ultrasonic frequency is 20kHz, the violet wavelength is 365nm, the light intensity is 10mW / cm2, and the inert atmosphere is a nitrogen atmosphere.

[0029] The acid-photocatalytic composite catalyst is prepared by the following method: dissolving ferric chloride hexahydrate and ferrous chloride tetrahydrate in deionized water at a molar ratio of 2:1, adding ammonia water to react for 35 minutes under a nitrogen atmosphere at 75°C, and obtaining ferrosoferric oxide particles after magnetic separation and washing; dispersing the ferrosoferric oxide particles in a 75wt% ethanol aqueous solution, adding ammonia water and ethyl orthosilicate, the mass volume ratio of ferrosoferric oxide particles, ammonia water, and ethyl orthosilicate g / mL is 1:0.05:0.2, reacting at 38°C for 6.5 hours, forming a silicon dioxide protective layer on the surface of the ferrosoferric oxide particles, and then dispersing the above-mentioned ferrosoferric oxide particles in toluene, adding (3-mercaptopropyl)trimethoxysilane, the ferrosoferric oxide particles, The mass-to-volume ratio of (3-mercaptopropyl)trimethoxysilane is 1:0.1, and the mixture is refluxed at 75°C for 13 hours. The refluxed product is immersed in 28wt% hydrogen peroxide and oxidized at 55°C for 6.5 hours to obtain sulfonic acid group-modified ferrosoferric oxide particles; the sulfonic acid group-modified ferrosoferric oxide particles are dispersed in anhydrous ethanol, and tetrabutyl titanate is added. The mass-to-volume ratio of the sulfonic acid group-modified ferrosoferric oxide particles and tetrabutyl titanate is 1:0.5. The mixture is ultrasonically treated for 35 minutes at an ultrasonic power of 200W and an ultrasonic frequency of 40kHz. A 1wt% hydrochloric acid solution is slowly added dropwise, and the mixture is hydrolyzed at 38°C for 3.2 hours. The mixture is then magnetically separated and washed, and calcined at 380°C for 2.1 hours to obtain an acid-photocatalytic composite catalyst.

[0030] S2. The crude zinc stearate product was added to anhydrous ethanol at 65° C. with a solid-liquid ratio of 0.08 g / mL and stirred to dissolve. An adsorbent was then added and adsorbed at 65° C. under an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz for 3 h. After adsorption, the adsorbent was separated and filtered out, and the filtrate was collected to obtain a refined zinc stearate solution.

[0031] The adsorbent is prepared by the following method: diatomaceous earth is placed in a 10wt% hydrochloric acid solution at 40°C with a solid-liquid ratio of 0.06g / mL and soaked for 120 minutes, the diatomaceous earth is separated and washed with deionized water to obtain an activated matrix; the activated matrix is ​​ultrasonically immersed in an aluminum-containing solution at 80°C for 14 hours, separated, and calcined at 400°C to obtain an activated intermediate. The method comprises dissolving aluminum nitrate in an aluminum-containing solution, with a mass ratio of the activated matrix to the aluminum ions in the aluminum-containing solution of 1:0.2. Ultrasonic impregnation is performed at an ultrasonic power of 200 W and a frequency of 40 kHz. Aminated graphene quantum dots are then dispersed in ethanol at a ratio of 0.5 wt%, and an activated intermediate is added at a mass ratio of 1:80. Ultrasonic treatment is performed at an ultrasonic power of 150 W and a frequency of 20 kHz for 35 minutes to obtain a graphene quantum dot-loaded intermediate. The graphene quantum dot-loaded intermediate is then immersed in a silane solution at 40°C for 50 minutes, separated, and dried at 80°C to obtain an adsorbent. The silane solute in the silane solution is γ-aminopropyltriethoxysilane.

[0032] S3. Cool the refined zinc stearate solution to 10° C. at a rate of 1° C. / min to precipitate crystals, filter, and take the crystals to obtain low-odor, high-purity zinc stearate.

[0033] Example 2

[0034] A method for preparing low-odor, high-purity zinc stearate comprises the following steps:

[0035] S1. In a liquid acidic environment with a pH of 3.5, stearic acid and zinc oxide are reacted in a molar ratio of 2:1.8 under the action of an acid-photocatalytic composite catalyst at 75°C, under a violet lamp and an inert atmosphere, and under an ultrasonic environment for 2 hours. The mass ratio of the acid-photocatalytic composite catalyst to zinc oxide is 2.5:100. The acid-photocatalytic composite catalyst is recovered and filtered to separate, and the solid is taken to obtain a crude zinc stearate product. The ultrasonic power is 350W, the ultrasonic frequency is 30kHz, the violet wavelength is 365nm, the light intensity is 30mW / cm2, and the inert atmosphere is a nitrogen atmosphere.

[0036] The acid-photocatalytic composite catalyst is prepared by the following method: dissolving ferric chloride hexahydrate and ferrous chloride tetrahydrate in deionized water at a molar ratio of 2:1, adding ammonia water to react for 30 minutes under a nitrogen atmosphere at 80°C, and obtaining ferrosoferric oxide particles after magnetic separation and washing; dispersing the ferrosoferric oxide particles in 80wt% ethanol aqueous solution, adding ammonia water and ethyl orthosilicate, the mass volume ratio of ferrosoferric oxide particles, ammonia water, and ethyl orthosilicate g / mL is 1:0.10:0.35, reacting at 40°C for 6.0h, forming a silicon dioxide protective layer on the surface of the ferrosoferric oxide particles, and then dispersing the above-mentioned ferrosoferric oxide particles in toluene, adding (3-mercaptopropyl)trimethoxysilane, the ferrosoferric oxide particles, The mass-to-volume ratio of (3-mercaptopropyl)trimethoxysilane is 1:0.2, and the mixture is refluxed at 80°C for 12 hours. The refluxed product is immersed in 30wt% hydrogen peroxide and oxidized at 60°C for 6.0 hours to obtain sulfonic acid group-modified ferrosoferric oxide particles. The sulfonic acid group-modified ferrosoferric oxide particles are dispersed in anhydrous ethanol, and tetrabutyl titanate is added. The mass-to-volume ratio of the sulfonic acid group-modified ferrosoferric oxide particles to tetrabutyl titanate is 1:0.8. The mixture is ultrasonically treated for 30 minutes at an ultrasonic power of 300W and an ultrasonic frequency of 50kHz. A 1wt% hydrochloric acid solution is slowly added dropwise, and the mixture is hydrolyzed at 40°C for 3.0 hours. The mixture is then magnetically separated and washed, and calcined at 400°C for 2.0 hours to obtain an acid-photocatalytic composite catalyst.

[0037] S2, adding the crude zinc stearate product to anhydrous ethanol at 70° C. at a solid-liquid ratio of 0.10 g / mL and stirring to dissolve, then adding an adsorbent and adsorbing at 70° C. under ultrasonic power of 300 W and ultrasonic frequency of 50 kHz for 2.5 h, separating and filtering out the adsorbent after adsorption, and taking the filtrate to obtain a refined zinc stearate solution;

[0038] The adsorbent is prepared by the following method: diatomaceous earth is placed in a 12.5wt% hydrochloric acid solution at 45°C with a solid-liquid ratio of 0.07g / mL and soaked for 100 minutes, the diatomaceous earth is separated and washed with deionized water to obtain an activated matrix; the activated matrix is ​​ultrasonically immersed in an aluminum-containing solution at 90°C for 12 hours, separated, and calcined at 450°C to obtain an activated intermediate. The method comprises dissolving aluminum chloride in an aluminum-containing solution, with a mass ratio of the activated matrix to the aluminum ions in the aluminum-containing solution of 1:0.25. Ultrasonic impregnation is performed at an ultrasonic power of 250 W and a frequency of 50 kHz. Aminated graphene quantum dots are then dispersed in ethanol at a ratio of 0.7 wt%, and an activated intermediate is added at a mass ratio of 1:90. Ultrasonic treatment is performed at an ultrasonic power of 200 W and a frequency of 30 kHz for 30 minutes to obtain a graphene quantum dot-loaded intermediate. The graphene quantum dot-loaded intermediate is then immersed in a silane solution at 45°C for 45 minutes, separated, and dried at 90°C to obtain an adsorbent. The silane solute in the silane solution is a 1:1 combination of γ-aminopropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane.

[0039] S3. Cool the refined zinc stearate solution to 7°C at a rate of 3°C / min to precipitate crystals, filter, and take the crystals to obtain low-odor, high-purity zinc stearate.

[0040] Example 3

[0041] A method for preparing low-odor, high-purity zinc stearate comprises the following steps:

[0042] S1. In a liquid acidic environment with a pH of 5.0, stearic acid and zinc oxide are reacted in a molar ratio of 2:2 under the action of an acid-photocatalytic composite catalyst at 80°C, under a violet lamp, in an inert atmosphere, and under an ultrasonic environment for 1 hour. The mass ratio of the acid-photocatalytic composite catalyst to zinc oxide is 5:100. The acid-photocatalytic composite catalyst is recovered and filtered to separate, and the solid is taken to obtain a crude zinc stearate product. The ultrasonic power is 500W, the ultrasonic frequency is 40kHz, the violet wavelength is 365nm, the light intensity is 50mW / cm2, and the inert atmosphere is argon atmosphere.

[0043] The acid-photocatalytic composite catalyst is prepared by the following method: dissolving ferric chloride hexahydrate and ferrous chloride tetrahydrate in deionized water at a molar ratio of 2:1, adding ammonia water to react for 25 minutes under a nitrogen atmosphere at 85°C, and obtaining ferrosoferric oxide particles after magnetic separation and washing; dispersing the ferrosoferric oxide particles in an 85wt% ethanol aqueous solution, adding ammonia water and ethyl orthosilicate, the mass volume ratio of ferrosoferric oxide particles, ammonia water, and ethyl orthosilicate g / mL is 1:0.15:0.5, reacting at 42°C for 5.5 hours, forming a silicon dioxide protective layer on the surface of the ferrosoferric oxide particles, and then dispersing the above-mentioned ferrosoferric oxide particles in toluene, adding (3-mercaptopropyl)trimethoxysilane, the ferrosoferric oxide particles, The mass-to-volume ratio of (3-mercaptopropyl)trimethoxysilane is 1:0.3 g / mL, and the mixture is refluxed at 85°C for 11 hours. The refluxed product is immersed in 32wt% hydrogen peroxide and oxidized at 65°C for 5.5 hours to obtain sulfonic acid group-modified ferrosoferric oxide particles; the sulfonic acid group-modified ferrosoferric oxide particles are dispersed in anhydrous ethanol, and tetrabutyl titanate is added. The mass-to-volume ratio of sulfonic acid group-modified ferrosoferric oxide particles and tetrabutyl titanate is 1:1.0. The mixture is ultrasonically treated at an ultrasonic power of 400W and an ultrasonic frequency of 60kHz for 25 minutes, and a 1wt% hydrochloric acid solution is slowly added dropwise. The mixture is hydrolyzed at 42°C for 2.8 hours, and then subjected to magnetic separation and washing, and calcined at 420°C for 1.9 hours to obtain an acid-photocatalytic composite catalyst.

[0044] S2. The crude zinc stearate product was added to anhydrous ethanol at 75° C. with a solid-liquid ratio of 0.12 g / mL and stirred to dissolve. An adsorbent was then added and adsorbed at 75° C. under an ultrasonic power of 400 W and an ultrasonic frequency of 60 kHz for 2 h. After adsorption, the adsorbent was separated and filtered out, and the filtrate was collected to obtain a refined zinc stearate solution.

[0045] The adsorbent is prepared by the following method: diatomaceous earth is placed in a 15wt% hydrochloric acid solution at 50°C with a solid-liquid ratio of 0.08g / mL and soaked for 80 minutes, the diatomaceous earth is separated and washed with deionized water to obtain an activated matrix; the activated matrix is ​​ultrasonically immersed in an aluminum-containing solution at 100°C for 14 hours, separated, and calcined at 500°C to obtain an activated intermediate. Aluminum sulfate is dissolved in an aluminum-containing solution, and the mass ratio of the activated matrix to the aluminum ions in the aluminum-containing solution is 1:0.3. Ultrasonic impregnation is performed at an ultrasonic power of 300W and a frequency of 60kHz. Aminated graphene quantum dots are then dispersed in ethanol at a ratio of 1wt%, and an activated intermediate is added at a mass ratio of 1:100. Ultrasonic treatment is performed at an ultrasonic power of 250W and a frequency of 40kHz for 25 minutes to obtain a graphene quantum dot-loaded intermediate. The graphene quantum dot-loaded intermediate is then immersed in a silane solution at 50°C for 40 minutes, separated, and dried at 100°C to obtain an adsorbent. The silane solute in the silane solution is a 1:1 combination of γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane.

[0046] S3. Cool the refined zinc stearate solution to 5°C at a rate of 5°C / min to precipitate crystals, filter, and take the crystals to obtain low-odor, high-purity zinc stearate.

[0047] Comparative Example 1

[0048] This comparative example is compared with Example 2, except that an equal mass of p-toluenesulfonic acid is used as a catalyst instead of the acid-photocatalytic composite catalyst.

[0049] Comparative Example 2

[0050] This comparative example is different from Example 2 in that the sulfonic acid group-modified ferrosoferric oxide particles obtained during the preparation of the acid-photocatalytic composite catalyst are used as the catalyst, that is, the subsequent addition of tetrabutyl titanate and the like is not performed during the preparation of the acid-photocatalytic composite catalyst, and the reaction in step S1 is not carried out under ultraviolet light conditions.

[0051] Comparative Example 3

[0052] This comparative example differs from Example 2 in that no adsorbent is added in step S2, and the following steps are followed: the crude zinc stearate product is added to anhydrous ethanol at 75° C. at a solid-to-liquid ratio of 0.12 g / mL, stirred and dissolved, and solid impurities are filtered out to obtain a refined zinc stearate solution.

[0053] Comparative Example 4

[0054] Compared with Example 2, this comparative example differs in that graphene quantum dots are not loaded during the preparation of the adsorbent. The adsorbent is prepared by the following method: diatomaceous earth is placed in a 12.5wt% hydrochloric acid solution at a solid-liquid ratio of 0.07g / mL and soaked for 100min in the 45°C 12.5wt% solution, the diatomaceous earth is separated and washed with deionized water to obtain an activated matrix; the activated matrix is ​​ultrasonically immersed in an aluminum-containing solution at 90°C for 12h, separated and calcined at 450°C to obtain an activated intermediate. Aluminum chloride is dissolved in the aluminum-containing solution, the mass ratio of the activated matrix to the aluminum ion in the aluminum-containing solution is 1:0.25, the ultrasonic power during ultrasonic immersion is 250W, and the ultrasonic frequency is 50kHz; the activated intermediate is then immersed in a silane solution at 45°C for 45min, separated and dried at 90°C to obtain the adsorbent. The silane solute in the silane solution is a 1:1 combination of γ-aminopropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane.

[0055] Performance testing

[0056] Twenty subjects aged 25-35 with normal sense of smell (male:female ratio 1:1) were selected to perform an odor test on the zinc stearate prepared in Examples 1-3 and Comparative Examples 1-4. After heating the zinc stearate to 50°C, the odor of the zinc stearate was evaluated according to the criteria in Table 1 below. Fresh air was breathed for 2 minutes between each test. The test results are shown in Table 2 below. The free acid content and zinc content of the zinc stearate in Example 13 and Comparative Examples 1-4 were also measured using the methods described in HG / T 3667-2012 Zinc Stearate. The results are shown in Table 2 below.

[0057] Table 1

[0058] Sensory description Review score No obvious odor 9.0-10 points Slight smell 5.0-8.9 points Has a strong odor 0-4.9 points

[0059] Table 2

[0060] Average odor rating Free acid content / % Zinc content / % Example 1 9.84 0.23 11.01 Example 2 9.93 0.22 10.98 Example 3 9.81 0.24 10.96 Comparative Example 1 5.65 0.56 10.99 Comparative Example 2 6.63 0.39 10.95 Comparative Example 3 5.28 0.45 10.94 Comparative Example 4 7.12 0.28 10.96

[0061] As can be seen from Table 2, the zinc stearate prepared in Examples 1-3 has no obvious odor and low free acid content.

[0062] The acid-photocatalytic composite catalyst of the present invention has a sulfonic acid group that provides an acidic site and directly catalyzes the esterification reaction of stearic acid and zinc oxide. The sulfonic acid group is fixed to the silicon dioxide layer by a covalent bond and is not easily lost, thereby reducing the residual free acid and lowering the acid value of the product, thereby reducing the odor. The titanium dioxide layer generated by the hydrolysis of tetrabutyl titanate generates hydroxyl radicals under the excitation of 365nm ultraviolet light, which degrades odorous byproducts such as aldehydes and ketones generated in the reaction. In addition, the titanium dioxide layer generates electron-hole pairs under the excitation of 365nm violet light, and the holes oxidize the surface of zinc oxide to generate Zn 2+, electrons reduce stearic acid to generate free radicals (R-COO - ), promoting an increase in reaction rate. The ferroferric oxide core imparts magnetic properties to the catalyst, allowing for rapid separation via a magnetic field, avoiding the residual problems associated with traditional liquid acid catalysts. The acid-photocatalytic composite catalyst achieves comprehensive improvements in efficiency, purity, and odor control in zinc stearate synthesis through the multifunctional synergy of acid catalysis, photocatalysis, ultrasonic enhancement, and magnetic recovery.

[0063] The adsorbent of the present invention adsorbs impurities containing lone-pair electrons through aluminum loading. Through graphene quantum dot loading, the conjugated structure of the graphene quantum dots interacts with aromatic impurities through π-π interactions, adsorbing aromatic hydrocarbon odor molecules. A three-dimensional network structure is formed through silane hydrolysis and condensation, which inhibits the adsorbent from swelling in ethanol and improves the adsorbent's stability. The adsorbent of this solution is designed through a four-step process: diatomaceous earth activation - aluminum loading - graphene quantum dot loading - silanization. This achieves efficient and specific impurity removal, significantly improving the purity and odor level of zinc stearate, and providing an innovative solution for the application of zinc stearate in the pharmaceutical and cosmetic fields.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing low-odor high-purity zinc stearate, characterized in that: The following steps are involved: S1. reacting stearic acid and zinc oxide in a liquid acidic environment under the action of an acid-photocatalytic composite catalyst, recovering the acid-photocatalytic composite catalyst and separating it by filtration, and taking a solid to obtain a crude zinc stearate product; S2, stirring and dissolving the crude zinc stearate product in anhydrous ethanol and adding an adsorbent, separating and filtering out the adsorbent after adsorption, and taking the filtrate to obtain a refined zinc stearate solution; S3. Cooling the refined zinc stearate solution to precipitate crystals, filtering and taking the crystals to obtain low-odor high-purity zinc stearate.

2. The method for preparing low-odor, high-purity zinc stearate according to claim 1, wherein: The molar ratio of stearic acid to zinc oxide in S1 is 2:(1.5-2), the pH of the acidic environment is 2.0-5.0, and the stearic acid and zinc oxide react at 70-80° C. under the action of an acid-photocatalytic composite catalyst for 1-3 hours.

3. The method for preparing a low-odor, high-purity zinc stearate according to claim 1, wherein: The mass ratio of the acid-photocatalytic composite catalyst to zinc oxide in S1 is (0.5-5):100, and the reaction is carried out under a violet lamp, an inert atmosphere and an ultrasonic environment.

4. The method for preparing low-odor, high-purity zinc stearate according to claim 3, wherein: Ultrasonic power is 200-500W, ultrasonic frequency is 20-40kHz, ultraviolet wavelength is 365nm, and light intensity is 10-50mW / cm 2 , the inert atmosphere is nitrogen or argon atmosphere.

5. The method for preparing low-odor, high-purity zinc stearate according to claim 3, wherein: The acid-photocatalytic composite catalyst is prepared by the following method: dissolving ferric chloride hexahydrate and ferrous chloride tetrahydrate in deionized water at a molar ratio of 2:1, adding ammonia water for reaction at 75-85° C. in a nitrogen atmosphere for 25-35 minutes, and obtaining ferroferric oxide particles after magnetic separation and washing; dispersing the ferroferric oxide particles in a 75-85wt% ethanol aqueous solution, adding ammonia water and tetraethyl orthosilicate, wherein the mass volume ratio of the ferroferric oxide particles, ammonia water, and tetraethyl orthosilicate is 1:(0.05-0.15):(0.2-0.5) g / mL, reacting at 38-42° C. for 5.5-6.5 hours, forming a silicon dioxide protective layer on the surface of the ferroferric oxide particles, and then dispersing the ferroferric oxide particles in toluene, adding (3-mercaptopropyl)trimethoxysilane, and the ferroferric oxide particles, (3-mercaptopropyl)trimethoxysilane, and the like. The method comprises the following steps: dispersing the sulfonic acid group-modified ferrosoferric oxide particles in anhydrous ethanol, adding tetrabutyl titanate, wherein the mass volume ratio of the sulfonic acid group-modified ferrosoferric oxide particles to the tetrabutyl titanate is 1:(0.1-0.3) in g / mL, and refluxing the mixture at 75-85° C. for 11-13 hours. The refluxed product is immersed in 28-32wt% hydrogen peroxide and oxidized at 55-65° C. for 5.5-6.5 hours to obtain sulfonic acid group-modified ferrosoferric oxide particles. The sulfonic acid group-modified ferrosoferric oxide particles are dispersed in anhydrous ethanol, and tetrabutyl titanate is added. The mass volume ratio of the sulfonic acid group-modified ferrosoferric oxide particles to the tetrabutyl titanate is 1:(0.5-1.0) in g / mL. The mixture is ultrasonically treated at an ultrasonic power of 200-400W and an ultrasonic frequency of 40-60kHz for 25-35 minutes. A 1wt% hydrochloric acid solution is slowly added dropwise, and the mixture is hydrolyzed at 38-42° C. for 2.8-3.2 hours. The mixture is then subjected to magnetic separation and washing, and calcined at 380-420° C. for 1.9-2.1 hours to obtain an acid-photocatalytic composite catalyst.

6. The method for preparing low-odor, high-purity zinc stearate according to claim 1, wherein: The crude zinc stearate product in S2 is added to anhydrous ethanol at 65-75°C at a solid-liquid ratio of 0.08-0.12 g / mL and stirred to dissolve. Then, an adsorbent is added and adsorbed at 65-75°C, an ultrasonic power of 200-400 W, and an ultrasonic frequency of 40-60 kHz for 2-3 hours. The S3 is cooled to 10-5°C at a rate of 1-5°C / min.

7. The method for preparing low-odor, high-purity zinc stearate according to claim 6, wherein: The adsorbent is prepared by the following method: placing diatomaceous earth at a solid-liquid ratio of 0.06-0.08 g / mL into a 10-15wt% hydrochloric acid solution at 40-50°C and soaking it for 80-120 minutes, separating the diatomaceous earth and washing it with deionized water to obtain an activated matrix; immersing the activated matrix in an aluminum-containing solution and separating and calcining it to obtain an activated intermediate; subsequently, dispersing amino-modified graphene quantum dots in ethanol at a ratio of 0.5-1wt% and adding the activated intermediate, wherein the mass ratio of the amino-modified graphene quantum dots to the activated intermediate is 1:80-100, and ultrasonically treating the mixture for 25-35 minutes under the conditions of an ultrasonic power of 150-250W and an ultrasonic frequency of 20-40kHz to obtain a graphene quantum dot-loaded intermediate; subsequently, immersing the graphene quantum dot-loaded intermediate in a silane solution and separating and drying it to obtain the adsorbent.

8. The method for preparing low-odor, high-purity zinc stearate according to claim 7, wherein: The aluminum-containing solution contains one of aluminum nitrate, aluminum chloride, and aluminum sulfate. The mass ratio of the activated matrix to the aluminum ions in the aluminum-containing solution is 1:(0.2-0.3). The activated matrix is ​​ultrasonically immersed in the aluminum-containing solution at 80-100° C., separated, and calcined at 400-500° C. to obtain an activated intermediate, which is ultrasonically immersed in the aluminum-containing solution for 10-14 hours. During the ultrasonic immersion, the ultrasonic power is 200-300 W and the ultrasonic frequency is 40-60 kHz.

9. The method for preparing low-odor, high-purity zinc stearate according to claim 7, wherein: The silane solute in the silane solution includes one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. The graphene quantum dot-loaded intermediate is immersed in the silane solution at 40-50° C. for 40-50 minutes. After separation, the intermediate is dried at 80-100° C. to obtain an adsorbent.

10. A low-odor, high-purity zinc stearate prepared by the preparation method according to any one of claims 1 to 9.