Method for preparing purity-adjustable ellagic acid by using valonia as raw material

Abstract

The invention discloses a method for preparing purity-adjustable ellagic acid by using valonia as a raw material, and belongs to the technical field of biological activity extraction. The method disclosed by the invention comprises the following steps: adding dilute sulphuric acid into a valonia raw material, carrying out ultrasonic treatment under a constant temperature condition, filtering, centrifuging, collecting precipitates, and drying to obtain an ellagic acid product, the ellagic acid products with different purities are regulated and controlled by adjusting the dosage ratio of valonia to dilute sulphuric acid. According to the method, the dilute sulphuric acid is adopted to replace ethyl alcohol to serve as an extraction solvent of valonia particles, macromolecular ellagic acid tannin can be synchronously hydrolyzed in the extraction process to produce ellagic acid, the ellagic acid is separated from other tannin in a precipitation form, and the purpose of producing high-purity ellagic acid through a one-pot method is achieved; ethanol can be avoided, so that the firefighting cost of storage is reduced, and the purity of tannic acid can be improved. The intermittent ultrasonic-assisted technology is adopted, the extraction yield and efficiency can be greatly improved, and the purpose of safely, efficiently, simply and conveniently extracting ellagic acid is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of biological activity extraction, and in particular relates to a method for preparing ellagic acid with adjustable purity by using rubber as a raw material. Background Art

[0002] Oak cups are the cups of plants in the Quercetin family, often used as forestry waste, and contain 15-34% tannins, most of which are ellagic acid tannins. Ellagic acid is a polyhydroxy tannin with astringent and bactericidal effects, and is widely used in pharmaceuticals, cosmetics, food and other industries. Especially in the leather industry, ellagic acid is an important tanning agent that can accelerate the tanning of leather. In addition, ellagic acid also has antioxidant and anti-inflammatory biological activities, and is used to study its therapeutic effects on certain diseases.

[0003] Currently, the industrial preparation of ellagic acid mostly requires the hydrothermal extraction method using ethanol as a solvent. This method not only has production safety risks, but is also accompanied by problems such as low yield and low product purity.

[0004] Ultrasonic assisted extraction is an efficient, simple and mature extraction method. It can improve the mass transfer efficiency between raw materials and solvents by using its cavitation effect and thermal effect. In addition to existing in free form, ellagic acid exists more in the form of macromolecular tannins, which can be hydrolyzed and release ellagic acid in an acidic environment. At the same time, ellagic acid is difficult to dissolve in an acidic environment and will be separated from other tannins in the form of precipitation.

[0005] Therefore, how to improve the extraction efficiency by changing the ethanol used as the extraction solvent in traditional technology and using ultrasound-assisted technology has become a problem that needs to be solved. Summary of the invention

[0006] The purpose of the present invention is to propose a method for preparing ellagic acid with adjustable purity using oak as raw material, wherein the purity of the ellagic acid product is adjusted by adjusting the dosage ratio of the raw material to the extraction solvent using oak as raw material; and the yield and extraction efficiency of ellagic acid are improved by combining the extraction process with ultrasound-assisted technology.

[0007] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing ellagic acid with adjustable purity using rubber bowl as raw material, comprising adding dilute sulfuric acid to the rubber bowl raw material, performing ultrasonic treatment under constant temperature conditions, filtering, centrifuging, collecting the precipitate and drying to obtain an ellagic acid product; and adjusting the dosage ratio of the rubber bowl to the dilute sulfuric acid to obtain ellagic acid products of different purities.

[0009] Furthermore, the particle size of the rubber bowl raw material is 40-80 meshes; the moisture content of the rubber bowl raw material is 11.42-12.74%.

[0010] Furthermore, the concentration of the dilute sulfuric acid is 0.1-1.0 wt.%.

[0011] Furthermore, the usage ratio of the rubber bowl raw material to the dilute sulfuric acid is 1:20-50.

[0012] Furthermore, the usage ratio of the rubber bowl raw material to the dilute sulfuric acid is 1:40.

[0013] Furthermore, the constant temperature condition is 30~50°C.

[0014] Furthermore, an interval ultrasonic treatment is adopted, and the method of the interval ultrasonic treatment is: ultrasonic treatment for 5 seconds every 5 seconds; the power of ultrasonic treatment is 132~528W, and the treatment time is 1~15min.

[0015] Furthermore, the centrifugal speed is 8000 rpm and the centrifugal time is 10 min.

[0016] Furthermore, any of the above methods for preparing ellagic acid with adjustable purity using rubber bowl as raw material comprises the following steps:

[0017] Step 1: First, crush the rubber bowl into 40-80 mesh particles and control the moisture content to 11.42-12.74%;

[0018] Step 2: weigh 5 g of the 40-80 mesh rubber bowl particles obtained in step 1 and put them into a 500 mL beaker, add 100-250 g of 0.1-1.0 wt.% sulfuric acid solution, place in a water bath at 30-50° C., and perform intermittent ultrasonic treatment at an ultrasonic power of 132-528 W and an ultrasonic extraction time of 1-15 min to obtain an extract;

[0019] Step 3: Filter the extract obtained in step 2 with a 500-1000 mesh filter bag, rinse the residue with 300 g of distilled water, and add the washing liquid to the filtrate to obtain a mixed liquid;

[0020] Step 4: The mixed liquid obtained in step 3 is centrifuged at 8000 rpm for 10 min to obtain a supernatant and a precipitate. After the precipitate is dried, the ellagic acid product is obtained.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1) The present invention uses dilute sulfuric acid instead of ethanol as the extraction solvent for the rubber bowl particles, which can simultaneously hydrolyze the macromolecular ellagic acid tannins to produce ellagic acid during the extraction process, and separate it from other tannins in the form of precipitation, so as to achieve the purpose of producing high-purity ellagic acid in a "one-pot method".

[0023] 2) The extraction method disclosed in the present invention can avoid ethanol to reduce the fire protection cost of storage and can improve the purity of tannic acid.

[0024] 3) The present invention uses intermittent ultrasonic-assisted technology in the process of extracting rubber with dilute sulfuric acid, which can greatly improve the extraction yield and efficiency, thereby achieving the purpose of extracting ellagic acid safely, efficiently and simply.

[0025] 4) The present invention can adjust the purity or content or extraction rate of the ellagic acid product by adjusting the dosage ratio of sulfuric acid to the raw material rubber bowl particles, changing the extraction temperature and the time of ultrasonic-assisted treatment. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0027] Unless otherwise specified, the raw materials used in the following examples are commercially available products.

[0028] In the following embodiments, the test or calculation methods used are as follows:

[0029] The moisture content of the rubber bowl particles was measured by an infrared moisture meter;

[0030] Ellagic acid content in the product: after dissolving the product in distilled water, the product was determined by HPLC;

[0031] The formula for calculating the purity of ellagic acid in the product is:

[0032] Purity of ellagic acid in the product (%) = mass of ellagic acid (mg) / absolute dry mass of the product (g) * 10;

[0033] The calculation formula of the extraction rate of ellagic acid in the product is: the extraction rate of ellagic acid in the product (mg / g) = the mass of ellagic acid (mg) / the absolute dry mass of the rubber bowl raw material (g);

[0034] A method for preparing ellagic acid with adjustable purity using rubber bowl as raw material, the steps are as follows:

[0035] (1) First, crush the rubber bowl into 40-80 mesh particles and control the moisture content to 11.42-12.74%;

[0036] (2) Weigh 5 g of the 40-80 mesh rubber bowl particles obtained in step (1) and put them into a 500 mL beaker, add 100-250 g of 0.1-1.0 wt.% sulfuric acid solution, place in a water bath at 25-50° C., and perform intermittent ultrasonic treatment (5 s ultrasonic treatment every 5 s), with an ultrasonic power of 132-528 W and an ultrasonic extraction time of 5 min to obtain an extract;

[0037] (3) filtering the extract obtained in step (2) with a 500-1000 mesh filter bag, washing the residue with 300 g of distilled water, and combining the washing liquid with the filtrate to obtain a mixed liquid;

[0038] (4) The mixed liquid obtained in step (3) is centrifuged at 8000 rpm for 10 min to obtain a supernatant and a precipitate. The precipitate is dried to obtain an ellagic acid product.

[0039] Example 1

[0040] A method for preparing ellagic acid with adjustable purity using rubber bowl as raw material, the steps are as follows:

[0041] (1) First, crush the rubber bowl into 40-80 mesh particles and control the moisture content to 12.74%;

[0042] (2) Weigh 5 g of the 40-80 mesh rubber bowl granules obtained in step (1) into a 500 mL beaker, add 200 g of distilled water, and perform water bath extraction at 50° C. for 15 min to obtain an extract;

[0043] (3) filtering the extract obtained in step (2) with a 500-mesh filter bag, washing the residue with 300 g of distilled water, and combining the washing liquid with the filtrate to obtain a mixed liquid;

[0044] (4) The mixed liquid obtained in step (3) is centrifuged at 8000 rpm for 10 min to obtain a supernatant and a precipitate. The precipitate is dried to obtain an ellagic acid product.

[0045] Example 2

[0046] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.1 wt.% sulfuric acid solution, and the other steps are the same as Example 1.

[0047] Example 3

[0048] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.2 wt.% sulfuric acid solution, and the other steps are the same as Example 1.

[0049] Example 4

[0050] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.4 wt.% sulfuric acid solution, and the other steps are the same as Example 1.

[0051] Example 5

[0052] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, and the other steps are the same as Example 1.

[0053] Example 6

[0054] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.8 wt.% sulfuric acid solution, and the other steps are the same as Example 1.

[0055] Example 7

[0056] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 1.0 wt.% sulfuric acid solution, and the other steps are the same as Example 1.

[0057] Example 8

[0058] Different from Example 1, in step (2), the extracting solution is replaced by 250 g of 0.5 wt.% sulfuric acid solution instead of 200 g of distilled water, and the extraction time is changed from 15 min to 1 min. The other steps are the same as Example 1.

[0059] Example 9

[0060] Different from Example 1, in step (2), the extracting solution is replaced by 250 g of 0.5 wt.% sulfuric acid solution instead of 200 g of distilled water, and the extraction time is changed from 15 min to 3 min. The other steps are the same as Example 1.

[0061] Example 10

[0062] Different from Example 1, in step (2), the extracting solution is replaced by 250 g of 0.5 wt.% sulfuric acid solution instead of 200 g of distilled water, and the extraction time is changed from 15 min to 5 min. The other steps are the same as Example 1.

[0063] Embodiment 11

[0064] Different from Example 1, in step (2), the extracting solution is replaced by 250 g of 0.5 wt.% sulfuric acid solution instead of 200 g of distilled water, and the extraction time is changed from 15 min to 10 min. The other steps are the same as Example 1.

[0065] Example 12

[0066] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, and the extraction temperature is changed from 50° C. to 25° C. The other steps are the same as Example 1.

[0067] Embodiment 13

[0068] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, and the extraction temperature is changed from 50° C. to 30° C. The other steps are the same as Example 1.

[0069] Embodiment 14

[0070] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, and the extraction temperature is changed from 50° C. to 35° C. The other steps are the same as Example 1.

[0071] Embodiment 15

[0072] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, and the extraction temperature is changed from 50° C. to 40° C. The other steps are the same as Example 1.

[0073] Example 16

[0074] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, and the extraction temperature is changed from 50° C. to 45° C. The other steps are the same as Example 1.

[0075] Embodiment 17

[0076] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, the extraction temperature is changed from 50°C to 35°C, and intermittent ultrasonic treatment is performed (ultrasonic treatment for 5 s every 5 s), the ultrasonic power is 132 W, and the ultrasonic extraction time is 7 min. The other steps are the same as in Example 1.

[0077] Embodiment 18

[0078] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, the extraction temperature is changed from 50°C to 35°C, and intermittent ultrasonic treatment is performed (ultrasonic treatment for 5 s every 5 s), the ultrasonic power is 264 W, and the ultrasonic extraction time is 7 min. The other steps are the same as in Example 1.

[0079] Embodiment 19

[0080] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, the extraction temperature is changed from 50°C to 35°C, and intermittent ultrasonic treatment is performed (ultrasonic treatment for 5 s every 5 s), the ultrasonic power is 396 W, and the ultrasonic extraction time is 7 min. The other steps are the same as in Example 1.

[0081] Embodiment 20

[0082] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, the extraction temperature is changed from 50°C to 35°C, and intermittent ultrasonic treatment is performed (ultrasonic treatment for 5 s every 5 s), the ultrasonic power is 528 W, and the ultrasonic extraction time is 7 min. The other steps are the same as in Example 1.

[0083] Embodiment 21

[0084] Different from Example 1, in step (2), the extracting solution is replaced by 200 g of distilled water with 200 g of 0.5 wt.% sulfuric acid solution, the extraction temperature is changed from 50° C. to 35° C., and intermittent ultrasonic treatment is performed (ultrasonic treatment for 5 s every 5 s), the ultrasonic power is 396 W, and the ultrasonic extraction time is 7 min; in step (3), the 500-mesh filter bag is replaced by a 1000-mesh filter bag, and the other steps are the same as in Example 1.

[0085] Comparative Example 1

[0086] A method for preparing ellagic acid, comprising the following steps:

[0087] (1) First, crush the rubber bowl into 40-80 mesh particles and control the moisture content to 12.74%;

[0088] (2) Weigh 5 g of the 40-80 mesh rubber bowl granules obtained in step (1) into a 500 mL beaker, add 100 g of distilled water, and perform water bath extraction at 25° C. for 5 min to obtain an extract;

[0089] (3) filtering the extract obtained in step (2) with a 500-mesh filter bag, washing the residue with 300 g of distilled water, and combining the washing liquid with the filtrate to obtain a mixed liquid;

[0090] (4) The mixed liquid obtained in step (3) is centrifuged at 8000 rpm for 10 min to obtain a supernatant and a precipitate. The precipitate is dried to obtain an ellagic acid product.

[0091] Comparative Example 2

[0092] A method for preparing ellagic acid with adjustable purity using rubber bowl as raw material, the steps are as follows:

[0093] (1) First, crush the rubber bowl into 40-80 mesh particles and control the moisture content to 12.74%;

[0094] (2) Weigh 5 g of the 40-80 mesh rubber bowl particles obtained in step (1) and put them into a 500 mL beaker, add 200 g of 95% ethanol, place in a water bath at 35°C, and perform intermittent ultrasonic treatment (5 seconds per 5 seconds interval), with an ultrasonic power of 396 W and an ultrasonic extraction time of 7 minutes to obtain an extract;

[0095] (3) filtering the extract obtained in step (2) with a 1000 mesh filter bag, washing the residue with 300 g of distilled water, and combining the washing liquid with the filtrate to obtain a mixed liquid;

[0096] (4) The mixed liquid obtained in step (3) is centrifuged at 8000 rpm for 10 min to obtain a supernatant and a precipitate. The precipitate is dried to obtain an ellagic acid product.

[0097] Comparative Example 3

[0098] A method for preparing ellagic acid with adjustable purity using pomegranate shell as a raw material, comprising the following steps:

[0099] (1) First, crush the pomegranate shell into particles of 40-80 mesh and control the moisture content to 12.74%;

[0100] (2) Weigh 5 g of the 40-80 mesh pomegranate shell particles obtained in step (1) and put them into a 500 mL beaker, add 200 g of 0.5 wt.% sulfuric acid solution, place in a water bath at 35° C., and perform intermittent ultrasonic treatment (ultrasonic treatment for 5 s every 5 s), the ultrasonic power is 396 W, and the ultrasonic extraction time is 7 min to obtain an extract;

[0101] (3) filtering the extract obtained in step (2) with a 1000 mesh filter bag, washing the residue with 300 g of distilled water, and combining the washing liquid with the filtrate to obtain a mixed liquid;

[0102] (4) The mixed liquid obtained in step (3) is centrifuged at 8000 rpm for 10 min to obtain a supernatant and a precipitate. The precipitate is dried to obtain an ellagic acid product.

[0103] Comparative Example 4

[0104] A method for preparing ellagic acid with adjustable purity using rubber bowl as raw material, the steps are as follows:

[0105] (1) First, crush the rubber bowl into 40-80 mesh particles and control the moisture content to 12.74%;

[0106] (2) Weigh 5 g of the 40-80 mesh rubber bowl particles obtained in step (1) and put them into a 500 mL beaker, add 50 g of 0.5 wt.% sulfuric acid solution, place in a water bath at 35°C, and perform intermittent ultrasonic treatment (5 seconds per 5 seconds interval), the ultrasonic power is 396 W, and the ultrasonic extraction time is 7 minutes to obtain an extract;

[0107] (3) filtering the extract obtained in step (2) with a 500-mesh filter bag, washing the residue with 300 g of distilled water, and combining the washing liquid with the filtrate to obtain a mixed liquid;

[0108] (4) The mixed liquid obtained in step (3) is centrifuged at 8000 rpm for 10 min to obtain a supernatant and a precipitate. The precipitate is dried to obtain an ellagic acid product.

[0109] The ellagic acid products prepared in Examples 1 to 21 and Comparative Examples 1 to 4 were respectively subjected to ellagic acid content determination, ellagic acid purity determination, ellagic acid extraction rate determination and absolute dry mass determination, and the test results are shown in Table 1 below.

[0110] Table 1 Comparison of the performance test results of the ellagic acid products obtained in Examples 1 to 5 and Comparative Examples 1 to 3

[0111]

[0112] By comparing the data of each group in Table 1 above, it is found that in Examples 1 to 21, the extraction rate of ellagic acid increases with the increase of sulfuric acid concentration, because ellagic acid exists in a monoprotonated form when pH is 5.6, and its solubility in water is extremely low, and some ellagic acid tannins can be hydrolyzed to produce ellagic acid under an acidic environment. With the increase of temperature, the mass transfer efficiency between the extraction raw material and the extraction solvent is improved, and the hydrolysis rate of ellagic acid tannins is also promoted. The extension of extraction time improves the extraction yield of ellagic acid, and extraction is carried out under the conditions of 0.5wt.% sulfuric acid concentration, 35°C, when the extraction time reaches 7min, the ellagic acid extraction yield can reach a higher level, and then the extraction yield tends to be stable, and extending the extraction time again can not significantly improve the ellagic acid extraction yield, because the ellagic acid tannins that can be hydrolyzed under dilute acid conditions in the raw material and the extract have been completely hydrolyzed, and the remaining ellagic acid tannins need to further increase acid concentration and temperature, which greatly increases production costs. Increasing the ultrasonic power can increase the extraction rate of ellagic acid, but further increasing the ultrasonic power after reaching 369 W cannot further increase the extraction rate of ellagic acid. The pore size selection of the filter bag has a decisive influence on the purity of ellagic acid. This is because although ellagic acid is the main product in the final product, it contains a large amount of insoluble rubber residue; at the same time, the pore size of ellagic acid crystals is smaller than most insoluble impurities. Using a smaller 1000 mesh filter bag can better select the particle size of the precipitate and separate more insoluble impurities from the product.

[0113] The present invention controls the content of ellagic acid in the product by increasing the concentration of sulfuric acid. The acid concentration has a great influence on the extraction yield of ellagic acid. When 0.5wt.% of sulfuric acid is added, the extraction yield of ellagic acid can be increased by 43.95% relative to that of distilled water extraction. At the same time, when the temperature is lower than 35°C and the extraction time reaches 7min, increasing the extraction temperature and extending the extraction time can increase the extraction yield of ellagic acid. Before the ultrasonic power reaches 369W, increasing the ultrasonic power can greatly increase the extraction yield of ellagic acid. Compared with not using ultrasonic assistance under the same conditions, ultrasonic-assisted extraction can increase the ellagic acid yield by up to 95.74%.

[0114] By comparing Example 21 with Comparative Example 1, it can be seen that during the extraction process, the solid-liquid ratio is increased to 1:40, sulfuric acid is added for acidolysis assistance, and interval ultrasound is used for auxiliary treatment, which can increase the extraction yield by 2.89 times. Increasing the solid-liquid ratio can increase the concentration difference of ellagic acid between the rubber bowl raw material and the solvent, and improve the mass transfer efficiency of ellagic acid; ellagic acid exists in a monoprotonated form at a pH of 5.6, and its solubility in water is extremely low. Most of the ellagic acid is precipitated from the solution, and some ellagic acid tannins can be hydrolyzed in an acidic environment to produce ellagic acid; the cavitation effect of ultrasound can produce microcavitation on the surface of the material, and these microcavitations When the bubble bursts, an instantaneous high-temperature area can be generated around it, which can promote the dissolution of ellagic acid without degrading it. In addition, since part of the ellagic acid and ellagic acid tannins are covalently bonded to the lignocellulose structure, the mechanical fragmentation effect of the ultrasound can fragment the rubber raw material at the microscopic level, thereby improving the accessibility between the solvent and the rubber raw material. At the same time, the large amount of phenolic hydroxyl groups on ellagic acid make it have a certain interfacial solubility in water, which can make ellagic acid diffuse from the surface of the lignocellulose structure of the rubber raw material to the surface of the solvent, and then precipitate after contacting with the main body of the solvent, thereby improving the extraction rate of ellagic acid.

[0115] By comparing Example 21 with Comparative Example 2, it can be seen that when ethanol is used instead of sulfuric acid for extraction, the extraction yield of the prepared ellagic acid product is greatly reduced. This is because the solubility of ellagic acid in ethanol is nearly 20 times that in water under the same conditions, and most of the ellagic acid exists in the solvent and cannot be separated in the form of a precipitate.

[0116] By comparing Example 21 with Comparative Example 3, it can be obtained that when the raw material is pomegranate shell, the yield of the prepared ellagic acid product is 7.91 mg / g and the purity is 92.10%. Compared with the case of using oak as the raw material, the yield of ellagic acid decreases, while the purity of the product increases. This is because the content of ellagic acid and ellagic acid tannin in the oak is higher than that in the pomegranate shell, but the oak contains a large amount of powdery secondary structures, some of which have a particle size similar to that of ellagic acid crystals, making it difficult to effectively separate them.

[0117] By comparing Example 1 with Comparative Example 4, it can be seen that when the solid-liquid ratio is reduced to 1:10, since the ellagic acid in the solvent has reached a saturated state, the mass transfer of ellagic acid is greatly inhibited. Compared with the use of a solid-liquid ratio of 1:40, the ellagic acid extraction rate is reduced by 35.19%, and compared with the use of a solid-liquid ratio of 1:20, the ellagic acid extraction rate is reduced by 27.93%.

[0118] The present invention uses 0.5% dilute sulfuric acid instead of ethanol as the extraction solvent, and can simultaneously hydrolyze large molecular ellagic acid tannins to produce ellagic acid during the extraction process, and separate it from other tannins in the form of precipitation, so as to achieve the purpose of producing high-purity ellagic acid in one pot. This method can avoid ethanol to reduce storage and fire protection costs, and can also improve the purity of tannic acid. At the same time, the cavitation effect of ultrasound-assisted ultrasound can produce micro-cavitation on the surface of the material. When these micro-cavitations burst, they can generate instantaneous high-temperature areas around them, which can promote the dissolution of ellagic acid without degrading ellagic acid. Moreover, since part of ellagic acid and ellagic acid tannins are covalently bonded to the lignocellulose structure, the mechanical fragmentation of ultrasound can fragment the microscopic level of the rubber bowl raw material, thereby improving the accessibility between the solvent and the rubber bowl raw material. At the same time, the large number of phenolic hydroxyl groups on ellagic acid make it have a certain interfacial solubility in water, which can make ellagic acid diffuse from the surface of the lignocellulose structure of the rubber bowl raw material to the surface of the solvent, and then precipitate out in the form of precipitation after contacting with the main body of the solvent, so as to improve the extraction rate and efficiency of ellagic acid and achieve the purpose of extracting ellagic acid safely, efficiently and simply. The invention adopts a solid-liquid ratio of 1:40, a sulfuric acid concentration of 0.5wt.%, a water bath at 35°C, and an interval ultrasonic treatment (ultrasonic treatment for 5s every 5s), an ultrasonic power of 396W, and an ultrasonic extraction time of 7min. After obtaining the extract, the extract is filtered using a 1000-mesh filter bag, and the filtrate is centrifuged at 8000rpm for 10min to obtain a supernatant and a precipitate. After the precipitate is dried, an ellagic acid product with an extraction yield of 13.69mg ellagic acid / g rubber bowl absolute dry raw material and a purity of 87.60% is obtained.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing ellagic acid with adjustable purity using rubber bowl as raw material, characterized in that: Add dilute sulfuric acid to the rubber bowl raw material, perform ultrasonic treatment under constant temperature conditions, filter, centrifuge, collect the precipitate and dry it to obtain the ellagic acid product; by adjusting the dosage ratio of the rubber bowl and the dilute sulfuric acid, the ellagic acid products of different purities can be obtained.

2. The method for preparing ellagic acid with adjustable purity using rubber bowl as raw material according to claim 1, characterized in that: The particle size of the rubber bowl raw material is 40-80 meshes; the moisture content of the rubber bowl raw material is 11.42-12.74%.

3. The method for preparing ellagic acid with adjustable purity using rubber bowl as raw material according to claim 1, characterized in that: The concentration of the dilute sulfuric acid is 0.1wt.%~1.0wt.%.

4. The method for preparing ellagic acid with adjustable purity using rubber bowl as raw material according to claim 1, characterized in that: The usage ratio of the rubber bowl raw material to the dilute sulfuric acid is 1:20-50.

5. The method for preparing ellagic acid with adjustable purity using rubber bowl as raw material according to claim 4, characterized in that: The usage ratio of the rubber bowl raw material to the dilute sulfuric acid is 1:

40.

6. The method for preparing ellagic acid with adjustable purity using rubber bowl as raw material according to claim 1, characterized in that: The constant temperature condition is 30~50℃.

7. The method for preparing ellagic acid with adjustable purity using rubber bowl as raw material according to claim 1, characterized in that: The method of the intermittent ultrasonic treatment is as follows: ultrasonic treatment for 5 seconds every 5 seconds; the power of the ultrasonic treatment is 132-528W, and the treatment time is 1-15 minutes.

8. The method for preparing ellagic acid with adjustable purity using rubber bowl as raw material according to claim 1, characterized in that: The centrifugal speed was 8000 rpm and the centrifugal time was 10 min.

9. The method for preparing ellagic acid with adjustable purity using rubber bowl as raw material according to any one of claims 1 to 8, characterized in that: Here are the steps: Step 1: First, crush the rubber bowl into 40-80 mesh particles and control the moisture content to 11.42-12.74%; Step 2: weigh 5 g of the 40-80 mesh rubber bowl particles obtained in step 1 and put them into a 500 mL beaker, add 100-250 g of 0.5 wt.% sulfuric acid solution, place in a water bath at 30-50° C., and perform intermittent ultrasonic treatment at an ultrasonic power of 132-528 W and an ultrasonic extraction time of 1-15 min to obtain an extract; Step 3: Filter the extract obtained in step 2 with a 500-1000 mesh filter bag, rinse the residue with 300 g of distilled water, and add the washing liquid to the filtrate to obtain a mixed liquid; Step 4: The mixed liquid obtained in step 3 is centrifuged at 8000 rpm for 10 min to obtain a supernatant and a precipitate. After the precipitate is dried, the ellagic acid product is obtained.

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