阅读说明：本技术 一种从工业大麻花叶中高效提纯大麻二酚的方法 (Method for efficiently purifying cannabidiol from industrial cannabis sativa leaves ) 是由 刘胜贵 王钲霖 薛红芬 孔令羽 蒋永昌 于 2021-09-24 设计创作，主要内容包括：本发明公开了一种从工业大麻花叶中高效提纯大麻二酚的方法,包括以下步骤：①原料预处理：将工业大麻花叶粉碎成20～40目的花叶颗粒；②超临界CO-(2)提取:将花叶颗粒置于萃取釜中萃取得到CBD含量为15～19%的提取物粗浸膏；③分子蒸馏：提取物粗浸膏进行分子蒸馏,得到CBD含量为30%～40%的轻组分；④色谱分离纯化：将轻组分溶解过滤,过滤得到的滤液上色谱层析柱,得到CBD含量为60～80%的CBD油；⑤结晶：将CBD溶解后,进行结晶,结晶完成后,对CBD饱和溶液进行过滤、干燥,得到含量99%以上的CBD晶体。本发明的提纯方法简单,流程短,收率高、产品纯度高,且整个提取纯化过程溶剂用量小,产品无溶剂残留,提取过程安全、无污染且生产成本低,可用于规模化生产。(The invention discloses a method for efficiently purifying cannabidiol from industrial cannabis sativa leaves, which comprises the following steps: pretreating raw materials: crushing industrial hemp leaves into 20-40 mesh flower and leaf particles; ② supercritical CO 2 Extracting, namely placing the mosaic granules in an extraction kettle for extraction to obtain an extract crude extract with the CBD content of 15-19%; ③ molecular distillation: performing molecular distillation on the crude extract to obtain a light component with the CBD content of 30-40%; chromatographic separation and purification: dissolving and filtering the light components, and carrying out chromatography column on the filtrate obtained by filtering to obtain CBD oil with the CBD content of 60-80%; fifthlyAnd (3) crystallization: and (3) dissolving the CBD, crystallizing, and filtering and drying the saturated CBD solution after the crystallization is finished to obtain the CBD crystal with the content of more than 99%. The purification method provided by the invention is simple, short in flow, high in yield, high in product purity, small in solvent consumption in the whole extraction and purification process, free of solvent residue in the product, safe in extraction process, free of pollution, low in production cost and capable of being used for large-scale production.)

1. A method for efficiently purifying cannabidiol from industrial cannabis sativa leaves is characterized by comprising the following steps:

pretreating raw materials: crushing the dried and impurity-removed industrial hemp flowers and leaves into 20-40-mesh flower and leaf particles by using a crusher;

② supercritical CO₂Extracting, namely placing the mosaic particles prepared in the step I into an extraction kettle, and adding CO₂Extracting for 2-4 h under the extraction conditions of extraction pressure of 20-30 MPa and extraction temperature of 40-55 ℃ by using ethanol as an entrainer as an extraction medium, and then analyzing under the conditions of separation pressure of 7-10 MPa and separation temperature of 40-50 ℃ to obtain an extract crude extract with the CBD content of 15-19%;

③ molecular distillation: preheating the temperature of a molecular distillation device to 100-150 ℃, introducing the crude extract of the extract prepared in the second step into the molecular distillation device from a feed inlet for molecular distillation, wherein the heating temperature of the molecular distillation is 150-200 ℃, the condensation temperature is 50-70 ℃, the film scraping rotating speed is 200-300 r/min, the vacuum degree is-0.05-0.09 MPa, and after the distillation is finished, a light component with the CBD content of 30-40% can be obtained;

chromatographic separation and purification: placing the light component prepared in the third step into a sample loading tank, and adding ethanol with the volume fraction of 60-70% into the sample loading tank, wherein the mass ratio of the ethanol to the light component is 5-10: 1; stirring until the light components are completely dissolved, filtering, wherein the filtering precision is 380-400 meshes, subjecting filtrate obtained by filtering to a chromatographic column, carrying sample amount is 20-50 mgCBD/mL, adopting 60-85% volume fraction ethanol solution as analytical eluent, dynamically eluting under the conditions of pressure of 20-40 bar and flow rate of 10-40 mL/min, firstly balancing 50-60% volume fraction ethanol solution, then eluting 5-10 times of column volume by using 60-85% volume fraction ethanol solution, eluting 5-10 times of column volume by using 60-85% volume fraction ethanol solution to elute target components, collecting enrichment solution rich in CBD components after elution, and then placing the collected enrichment solution in a concentration tank to concentrate into thick paste to obtain CBD oil with CBD content of 60-80% under reduced pressure;

crystallization: and (4) placing the CBD oil prepared in the step (iv) into a dissolving tank, adding a crystallization solvent into the dissolving tank, wherein the mass ratio of the crystallization solvent to the CBD oil is 1: 1-1.5, stirring until the CBD oil is completely dissolved to obtain a CBD saturated solution, then placing the CBD saturated solution into a crystallizing tank, crystallizing for 24-48 hours at the temperature of-10 to-20 ℃, filtering the CBD saturated solution after crystallization is completed, placing the filtered crystal into a vacuum drying oven, and drying at the temperature of 40-60 ℃ to obtain the CBD crystal with the content of more than 99%.

2. The method for efficiently purifying cannabidiol from industrial hemp flowers and leaves as claimed in claim 1, wherein in the step (i), before the industrial hemp flowers and leaves are crushed, the industrial hemp is soaked in water, then is put into a sieve basket and is wholly immersed into liquid nitrogen for 20-30 min, then is lifted and is placed at room temperature for 5-10 min, then the sieve basket is wholly immersed into the liquid nitrogen for 20-30 min, and after the steps are repeated for 2-3 times, the industrial hemp is dried at low temperature to reduce the water content to below 5%.

3. The method for efficiently purifying cannabidiol from industrial cannabis sativa leaves as claimed in claim 1, wherein in step (ii), the entrainer is ethanol with a volume fraction of 90-95%.

4. The method for efficiently purifying cannabidiol from industrial cannabis sativa leaves as claimed in claim 1, wherein in step three, the feeding flow rate of the crude extract into the molecular distillation device is 1-2 g/min.

5. The method for efficiently purifying cannabidiol from industrial cannabis sativa leaves as claimed in claim 1, wherein in the step (iv), the pressure for the concentration under reduced pressure is-0.04 to-0.07 MPa, and the temperature is 40 to 60 ℃.

6. The method for efficiently purifying cannabidiol from industrial cannabis sativa leaves as claimed in claim 1, wherein in the step (iv), the chromatography medium in the chromatography column is any one of chromatography packing resin, reverse phase silica gel and polymer reverse phase chromatography packing.

7. The method for efficiently purifying cannabidiol from industrial cannabis sativa leaves as claimed in claim 1, wherein in step (v), the crystallization solvent is 1: 10-20 v/v dichloromethane and n-hexane.

Technical Field

The invention belongs to the technical field of biological medicines, and particularly relates to a method for efficiently purifying cannabidiol from industrial cannabis sativa leaves.

Background

Industrial hemp refers to a hemp that has been legally planted and contains less than 0.3% Tetrahydrocannabinol (THC). At present, industrial hemp is planted in Yunnan province, Heilongjiang province and other places in large scale, and the planting scale is enlarged year by year. The industrial HEMP (HEMP) has extremely high medicinal value and wide application, and relates to the fields of textile, paper making, food, medicine, sanitation, daily chemicals, leather, automobiles, buildings, decoration, packaging and the like. Is a classic production material and is also one of the traditional raw materials of medicinal materials and health care products in China. Among cannabinoids currently isolated from industrial cannabis, there are over 80 cannabinoids including Cannabidiol (CBD), cannabidiolic acid (CBDA), Cannabidivarin (CBDV) Tetrahydrocannabinol (THC), Cannabinol (CBN), (cannabigerol, CBG) and the like, of which CBD and THC contents are the highest. Research shows that CBD has obvious curative effect on epilepsy treatment, sedation, analgesia, antidepressant, anxiolysis, anti-inflammation and the like, and especially in recent years, the wave of CBD products including CBD cosmetics, foods, beverages, medicines, health care products and the like is raised in countries in Europe and America, wherein one of the most popular products is CBD oil.

In the prior art, there are two common methods for extracting cannabidiol from industrial hemp, one is organic solvent extraction, the other is supercritical carbon dioxide extraction, different extraction modes are matched with different rear-end separation and purification processes, and the organic solvent extraction process mainly comprises: crushing, high-temperature conversion decarboxylation, extraction, alcohol precipitation, dewaxing, molecular distillation, chromatography, crystallization and the like, the method has large organic solvent dosage and more types of used organic solvents, the residual organic solvents in the extract easily exceed the standard, the product quality is reduced, the environmental pollution is serious, and the supercritical carbon dioxide extraction process comprises the following steps: for example, chinese patent 2019103699082 discloses a method for extracting cannabidiol from industrial hemp, which comprises the following steps: the method comprises the following steps of removing impurities from raw materials, crushing, drying, extracting by supercritical carbon dioxide, distilling molecules, and separating and purifying by supercritical fluid chromatography, wherein supercritical carbon dioxide is used as a mobile phase, ethanol is mainly used as an entrainer in the process, and cannabidiol enriched substances are separated and purified, so that the process is high in production cost and is not suitable for industrial popularization; for another example, chinese patent 2020108510830 discloses a method for extracting purified cannabidiol from industrial cannabis sativa, comprising the steps of: the method comprises the following steps of crushing raw materials, drying, extracting with a solvent, dewaxing, molecular distillation, column chromatography, concentrating and recrystallizing, wherein the extraction adopts one or more of ethanol, n-hexane, petroleum ether and ethyl acetate, the elution solvent is a mixture of two or more of ethyl acetate, chloroform, dichloromethane, n-hexane and petroleum ether according to a volume ratio, the crystallization solvent is n-heptane, the solvent used in the extraction process is complex, organic solvent residues are easily caused, and the purity of extracted CBD is low, so that the product quality is influenced; further, as disclosed in chinese patent 2020115363268, a method for industrially and cleanly producing cannabidiol CBD broad-spectrum oil, the preparation steps are as follows: sieving to remove impurities, crushing, drying, ethanol extraction, concentration, ultra-low temperature degreasing and dewaxing, decoloring, molecular distillation, industrial preparative chromatography separation and purification, and vacuum concentration, wherein the decarboxylation and conversion of the CBDA are synchronously completed in the molecular distillation process, the whole process of the invention only uses an ethanol water system, and clean production is realized, but the process has the following defects: the process route is long, and simultaneously, because the ethanol extraction is adopted, the extract contains a large amount of water-soluble compounds, high molecular oil compounds and a large amount of pigment substances, the impurity content is high, most of impurities can be removed only by dewaxing, decoloring and molecular distillation, the CBD content in the extract is improved, the process is complex, time and labor are wasted, and the problem of low product yield is easily caused. By studying the existing process route, the supercritical extraction mainly has the following defects: firstly, the existing extraction process has a long route, the operation process is relatively complicated, and the extraction rate of CBD is low; secondly, high-temperature conversion is carried out on the flower and leaf raw materials or the extracted extract so as to convert CBDA into CBD, the next process link is carried out after the conversion is finished, particularly, high-temperature drying equipment with a certain scale is required to be added for the conversion of the flower and leaf raw materials, the high-temperature drying equipment needs to consume more heat energy, and the investment and operation cost is higher; thirdly, the existing CBD separation and purification process uses a complex solvent type and has high solvent toxicity, which not only easily causes the residue of organic solvent, reduces the extraction purity of CBD and influences the product quality of CBD, but also causes serious environmental pollution due to the discharge of organic solvent. Therefore, it is objectively needed to develop a method for efficiently purifying cannabidiol from industrial cannabis leaves, which has short process route, simple operation and low operation cost, and can effectively improve the product extraction rate and the product purity.

Disclosure of Invention

In order to solve the problems in the prior art, the invention aims to provide a method for efficiently purifying cannabidiol from industrial cannabis leaves, which has the advantages of short process route, simple operation and low operation cost, and can effectively improve the product extraction rate and the product purity

The method for efficiently purifying the cannabidiol from the industrial cannabis sativa leaves comprises the following steps:

pretreating raw materials: crushing the dried and impurity-removed industrial hemp flowers and leaves into 20-40-mesh flower and leaf particles by using a crusher, soaking the industrial hemp flowers and leaves with water before crushing, putting the industrial hemp flowers and leaves into a sieve basket, wholly immersing the sieve basket into liquid nitrogen for 20-30 min, lifting, placing the sieve basket at room temperature for 5-10 min, wholly immersing the sieve basket into the liquid nitrogen for 20-30 min, repeating the operation for 2-3 times, and drying the industrial hemp flowers and leaves at low temperature to reduce the water content of the industrial hemp to below 5%;

② supercritical CO₂Extracting, namely placing the mosaic particles prepared in the step I into an extraction kettle, and adding CO₂Ethanol with the volume fraction of 90-95 percent is used as an entrainer as an extraction medium under the extraction pressureExtracting and extracting for 2-4 h under the conditions that the force is 20-30 MPa and the extraction temperature is 40-55 ℃, and resolving under the conditions that the separation pressure is 7-10 MPa and the separation temperature is 40-50 ℃ to obtain an extract crude extract with the CBD content of 15-19%;

③ separating and distilling: preheating the temperature of a molecular distillation device to 100-150 ℃, introducing the crude extract of the extract prepared in the second step into the molecular distillation device from a feed inlet for molecular distillation, wherein the heating temperature of the molecular distillation is 150-200 ℃, the condensation temperature is 50-70 ℃, the film scraping rotation speed is 200-300 r/min, the vacuum degree is-0.05-0.09 MPa, and after the distillation is finished, a light component with the CBD content of 30-40% can be obtained;

chromatographic separation and purification: placing the light component prepared in the third step into a sample loading tank, and adding ethanol with the volume fraction of 60-70% into the sample loading tank, wherein the mass ratio of the ethanol to the light component is 5-10: 1; stirring until the light components are completely dissolved, filtering, wherein the filtering precision is 380-400 meshes, subjecting filtrate obtained by filtering to a chromatographic column, carrying sample amount is 20-50 mgCBD/mL, dynamically eluting eluent by adopting an ethanol solution with volume fraction of 60-85% under the conditions of pressure of 20-40 bar and flow rate of 10-40 mL/min, balancing the eluent by using the ethanol solution with volume fraction of 50-60% during elution, eluting 5-10 times of column volume by using the ethanol solution with volume fraction of 60-85%, eluting the target component by using 5-10 times of column volume by using the ethanol solution with volume fraction of 60-85%, collecting enrichment liquid rich in CBD components after elution, and concentrating the collected enrichment liquid in a concentration tank to obtain CBD oil with CBD content of 60-80% under reduced pressure;

crystallization: placing the CBD oil prepared in the step IV into a dissolving tank, adding a crystallization solvent into the dissolving tank, wherein the crystallization solvent is dichloromethane and n-hexane with the volume ratio of 1: 10-20 v/v, the mass ratio of the crystallization solvent to the CBD oil is 1: 1-1.5, stirring until the CBD oil is completely dissolved to obtain a CBD saturated solution, then placing the CBD saturated solution into the crystallizing tank, crystallizing for 24-48 hours at the temperature of-10 to-20 ℃, filtering the CBD saturated solution after crystallization is completed, placing the filtered crystal into a vacuum drying oven, and drying at the temperature of 40-60 ℃ to obtain the CBD crystal with the content of more than 99%.

Compared with the prior art, the invention has the following beneficial effects:

firstly, the invention simplifies the supercritical CO₂According to the back-end separation process after extraction, the technical parameters of the back-end separation and purification process are reasonably optimized, the molecular distillation is directly carried out on the extract crude extract after supercritical extraction, the original process links such as high-temperature conversion decarboxylation, dewaxing decoloration and the like are omitted, the process route of CBD extraction and impurity removal is shortened, the process route is shortened, the operation difficulty in the CBD extraction process is effectively reduced, the CBD yield is improved, the whole production process flow is easier to implement and control, and the advantages of simplicity in operation and controllability in the production process are achieved;

secondly, the molecular distillation is directly carried out on the coarse extract after the supercritical extraction, the conversion decarboxylation of the CBDA in the extract can be synchronously completed in the impurity removal process, so that the content of the CBD is improved, the flower and leaf raw material conversion process is omitted, the investment of high-temperature drying equipment is saved, the energy consumption in the extraction process is reduced, the production cost is effectively reduced, and the method is suitable for large-scale production;

thirdly, the process has small organic solvent consumption in the whole production process, only 2 process links of chromatographic separation, purification and crystallization use the organic solvent, the used solvents are few in variety, only ethanol, water and a small amount of crystallization solvents, namely n-hexane and dichloromethane are used, and the separated CBD has no organic solvent residue and is a green, environment-friendly and economic extraction method;

and fourthly, the invention adopts a process combining molecular distillation and chromatographic separation and purification, has the advantages of high separation efficiency, good CBD oil color and high purity, and can effectively reduce the loss of CBD components and greatly improve the yield of CBD.

Drawings

FIG. 1 is supercritical CO of example 1₂Liquid chromatogram of CBD and CBDA in the crude extract;

FIG. 2 is a liquid chromatogram of CBD and CBDA in the light fraction after molecular distillation in example 1;

FIG. 3 is a liquid chromatogram of the CBD oil obtained from the chromatographic separation and purification of example 1;

FIG. 4 is a liquid chromatogram of the CBD crystals crystallized in example 1;

FIG. 5 is a liquid chromatogram of a CBD standard.

Detailed Description

The invention is further illustrated by the following description of embodiments and the accompanying drawings, without in any way limiting the invention, and any alterations or substitutions made on the basis of the teachings of the invention shall fall within the scope of protection of the invention.

Example 1:

the method for efficiently purifying cannabidiol from industrial cannabis sativa leaves as described in example 1 comprises the following steps:

pretreating raw materials: crushing the dried and impurity-removed industrial hemp flowers and leaves into 20-mesh flower and leaf particles by using a crusher, soaking the industrial hemp flowers and leaves with water before crushing, putting the industrial hemp flowers and leaves into a sieve blue, immersing the sieve blue into liquid nitrogen for 20min, lifting and placing the sieve blue at room temperature for 5min, immersing the sieve blue into the liquid nitrogen for 20min, repeating the operation for 2-3 times, drying the industrial hemp at a low temperature to reduce the water content to below 5%, immersing the industrial hemp flowers and leaves into low-temperature liquid nitrogen, freezing the water in the industrial hemp flower and leaf cell liquid, increasing the volume and puncturing the cell walls, precipitating effective components in the industrial hemp flower and leaf cells, and drying the industrial hemp flower and leaves under the low-temperature condition to ensure that the effective components in the industrial hemp flower and leaf cells are not lost;

② supercritical CO₂Extracting by placing 100kg (CBD content 0.5%) of the flower and leaf granules prepared in the step I in an extraction kettle with CO₂Extracting with 90% ethanol as entrainer under 20MPa and 40 deg.C for 2 hr, and separating under 7MPa and 40 deg.C to obtain 2.75kg of crude extract with CBD content of 18.5%;

③ molecular distillation: preheating the temperature of a molecular distillation device to 100 ℃, introducing the crude extract of the extract prepared in the second step into the molecular distillation device from a feed inlet for molecular distillation, wherein the feed flow of the crude extract of the extract entering the molecular distillation device is 1g/min, the heating temperature of the molecular distillation is 150 ℃, the condensation temperature is 50 ℃, the rotating speed of a film scraping is 200 r/min, the vacuum degree is-0.05 MPa, and after the distillation is finished, 1.27kg of light components with the CBD content of 39.2 percent can be obtained;

chromatographic separation and purification: placing the light component prepared in the third step into a sample loading tank, and adding 60% ethanol by volume into the sample loading tank, wherein the mass ratio of the ethanol to the light component is 9: 1; stirring until the light components are completely dissolved, filtering with the filtering precision of 380 meshes, loading the filtrate obtained by filtering onto a chromatographic column, wherein a chromatographic medium in the chromatographic column is any one of chromatographic packing resin, reverse phase silica gel and polymer reverse phase chromatographic packing, the sample loading amount is 28mgCBD/mL, dynamic elution is carried out on the analytical eluent by adopting an ethanol solution with the volume fraction of 60% under the conditions of the pressure of 20bar and the flow rate of 10mL/min, during elution, the ethanol solution with the volume fraction of 50% is used for balancing, the ethanol solution with the volume fraction of 60% is used for eluting 5 times of the column volume, then the target component is eluted by using the ethanol solution with the volume of 60% for 5 times of the column volume, after elution, the enriched liquid rich in the CBD components is collected, then the collected enriched liquid is placed in a concentration tank and concentrated into thick paste under reduced pressure, and the pressure of reduced pressure is-0.04 MPa, the temperature is 40 ℃, thus obtaining 0.569kg of CBD oil with the CBD content of 79.6 percent;

crystallization: placing the CBD oil prepared in the step (iv) into a dissolving tank, adding a crystallization solvent into the dissolving tank, wherein the crystallization solvent is dichloromethane and n-hexane with the volume ratio of 1:18v/v, the mass ratio of the crystallization solvent to the CBD oil is 1:1, stirring until the CBD oil is completely dissolved to obtain a CBD saturated solution, then placing the CBD saturated solution into a crystallizing tank, crystallizing for 24 hours at the temperature of-10 ℃, filtering the CBD saturated solution after crystallization is completed, placing the filtered crystal into a vacuum drying oven, and drying at the temperature of 40 ℃ to obtain 0.422kg of CBD crystal with the content of 99.5%.

The method of the embodiment 1 has the characteristics of higher purity, higher extraction rate and higher extraction speed of the CBD, and after chromatographic separation of the material containing the CBD component obtained in each stage of the embodiment 1, the purity of the CBD crystal obtained by final concentration can reach 99.5%, and the CBD yield reaches 84.0%.

Example 2:

the method for efficiently purifying cannabidiol from industrial cannabis sativa leaves in example 2 comprises the following steps:

pretreating raw materials: crushing the dried and impurity-removed industrial hemp flowers and leaves into 30-mesh flower and leaf particles by using a crusher, soaking the industrial hemp flowers and leaves with water before crushing, putting the industrial hemp flowers and leaves into a sieve blue, immersing the sieve blue into liquid nitrogen for 25min, lifting and placing the sieve blue at room temperature for 8min, immersing the sieve blue into the liquid nitrogen for 25min, repeating the steps for 2-3 times, drying the industrial hemp at a low temperature to reduce the water content to below 5%, immersing the industrial hemp flowers and leaves into low-temperature liquid nitrogen, freezing the water in the industrial hemp flower and leaf cell liquid, increasing the volume, puncturing the cell walls, precipitating effective components in the industrial hemp flower and leaf cells, and drying the industrial hemp flower and leaves under the low-temperature condition to ensure that the effective components in the industrial hemp flower and leaf cells are not lost;

② supercritical CO₂Extracting by placing 100kg (CBD content 0.5%) of the mosaic granules prepared in the step I in an extraction kettle with CO₂Extracting with 92% ethanol as entrainer under 25MPa and 50 deg.C for 3 hr, and separating under 8MPa and 45 deg.C to obtain 2.73kg of crude extract with CBD content of 17.2%;

③ molecular distillation: preheating the temperature of a molecular distillation device to 140 ℃, introducing the crude extract of the extract prepared in the second step into the molecular distillation device from a feed inlet for molecular distillation, wherein the feed flow of the crude extract of the extract entering the molecular distillation device is 1.5g/min, the heating temperature of the molecular distillation is 180 ℃, the condensing temperature is 60 ℃, the rotating speed of a film scraping is 240 r/min, the vacuum degree is-0.08 MPa, and after the distillation is finished, 1.38kg of light components with the CBD content of 36.5 percent can be obtained;

chromatographic separation and purification: placing the light component prepared in the third step into a sample loading tank, and adding ethanol with the volume fraction of 60-70% into the sample loading tank, wherein the mass ratio of the ethanol to the light component is 7: 1; stirring until the light components are completely dissolved, filtering, wherein the filtering precision is 390 meshes, applying a chromatographic column to filtrate obtained by filtering, wherein a chromatographic medium in the chromatographic column is any one of chromatographic packing resin, reverse phase silica gel and polymer reverse phase chromatographic packing, the sample loading amount is 35mgCBD/mL, dynamic elution is carried out on analytical eluent by adopting an ethanol solution with the volume fraction of 70% under the conditions of the pressure of 30bar and the flow rate of 30mL/min, during elution, the ethanol solution with the volume fraction of 55% is used for balancing, the ethanol solution with the volume fraction of 75% is used for eluting 8 times of the column volume, then 75% of the ethanol solution is used for eluting the target component by 8 times of the column volume, collecting enrichment solution rich in the CBD components after elution, then placing the collected enrichment solution in a concentration tank, concentrating into thick paste under reduced pressure, and the pressure of-0.06 MPa, the temperature is 50 ℃, and 0.621kg of CBD oil with the CBD content of 72 percent can be obtained;

crystallization: placing the CBD oil prepared in the step (iv) into a dissolving tank, adding a crystallization solvent into the dissolving tank, wherein the crystallization solvent is dichloromethane and n-hexane with the volume ratio of 1:15v/v, the mass ratio of the crystallization solvent to the CBD oil is 1:1, stirring until the CBD oil is completely dissolved to obtain a CBD saturated solution, then placing the CBD saturated solution into a crystallizing tank, crystallizing for 35 hours at the temperature of-15 ℃, filtering the CBD saturated solution after crystallization is completed, placing the filtered crystal into a vacuum drying oven, and drying at the temperature of 50 ℃ to obtain 0.432kg of the CBD crystal with the content of 99.3%.

The method of embodiment 2 has the characteristics of higher purity, higher extraction rate and faster extraction speed of CBD, and after chromatographic separation of the material containing the CBD component obtained in each stage of embodiment 2, it is found that the purity of the finally concentrated CBD crystal can reach 99.3%, and the CBD yield reaches 85.8%.

Example 3:

the method for efficiently purifying cannabidiol from industrial cannabis sativa leaves in embodiment 3 comprises the following steps:

pretreating raw materials: crushing the dried and impurity-removed industrial hemp flowers and leaves into 40-mesh flower and leaf particles by using a crusher, soaking the industrial hemp flowers and leaves with water before crushing, putting the industrial hemp flowers and leaves into a sieve blue, immersing the sieve blue into liquid nitrogen for 30min, lifting and placing the sieve blue at room temperature for 10min, immersing the sieve blue into the liquid nitrogen for 30min, repeating the steps for 2-3 times, drying the industrial hemp at low temperature to reduce the water content to below 5%, immersing the industrial hemp flowers and leaves into low-temperature liquid nitrogen, freezing the water in the industrial hemp flower and leaf cell liquid, increasing the volume, puncturing the cell walls, precipitating effective components in the industrial hemp flower and leaf cells, and drying the industrial hemp flower and leaves under the low-temperature condition to ensure that the effective components in the industrial hemp flower and leaf cells are not lost;

② supercritical CO₂Extracting by placing 100kg (CBD content 0.5%) of the mosaic granules prepared in the step I in an extraction kettle with CO₂Extracting with 95% ethanol as entrainer under 30MPa and 55 deg.C for 4 hr, and separating under 9MPa and 50 deg.C to obtain 2.94kg of crude extract with 15.8% of CBD content;

③ molecular distillation: preheating the temperature of a molecular distillation device to 150 ℃, introducing the crude extract of the extract prepared in the second step into the molecular distillation device from a feed inlet for molecular distillation, wherein the feed flow of the crude extract of the extract entering the molecular distillation device is 2g/min, the heating temperature of the molecular distillation is 200 ℃, the condensing temperature is 70 ℃, the rotating speed of a film scraping is 280 r/min, the vacuum degree is-0.09 MPa, and after the distillation is finished, 1.462kg of light components with the CBD content of 32.7 percent can be obtained;

chromatographic separation and purification: placing the light component prepared in the third step into a sample loading tank, and adding ethanol with the volume fraction of 60-70% into the sample loading tank, wherein the mass ratio of the ethanol to the light component is 6: 1; stirring until the light components are completely dissolved, filtering, wherein the filtering precision is 400 meshes, applying a chromatographic column to filtrate obtained by filtering, wherein a chromatographic medium in the chromatographic column is any one of chromatographic packing resin, reverse phase silica gel and polymer reverse phase chromatographic packing, the sample loading amount is 40mgCBD/mL, the analytical eluent adopts 85% ethanol solution in volume fraction, dynamically eluting under the conditions of 40bar pressure and 40mL/min flow rate, during elution, the 60% ethanol solution in volume fraction is used for balancing, the 85% ethanol solution is used for eluting 10 times of the column volume, then the 85% ethanol solution is used for eluting 10 times of the column volume to elute the target components, collecting the enriched liquid rich in the CBD components after elution, then placing the collected enriched liquid in a concentration tank, concentrating under reduced pressure to obtain thick paste, and the pressure of the concentrated under reduced pressure is-0.07 MPa, the temperature is 60 ℃, thus obtaining 0.691kg of CBD oil with the CBD content of 64 percent;

crystallization: placing the CBD oil prepared in the step (iv) into a dissolving tank, adding a crystallization solvent into the dissolving tank, wherein the crystallization solvent is dichloromethane and n-hexane with the volume ratio of 1:10v/v, the mass ratio of the crystallization solvent to the CBD oil is 1:1, stirring until the CBD oil is completely dissolved to obtain a CBD saturated solution, then placing the CBD saturated solution into a crystallizing tank, crystallizing at the temperature of-10 ℃ for 24 hours, filtering the CBD saturated solution after crystallization is completed, placing the filtered crystal into a vacuum drying oven, and drying at the temperature of 40 ℃ to obtain 0.417kg of CBD crystal with the content of 99.1%.

The method of the embodiment 3 has the characteristics of higher purity, higher extraction rate and higher extraction speed of the CBD, and after chromatographic separation of the material containing the CBD component obtained in each stage of the embodiment 3, the purity of the CBD crystal obtained by final concentration can reach 99.1%, and the CBD yield reaches 82.6%.

The purification method of the above examples 1 to 3 is simple, short in flow and high in extraction rate. The product has high purity, no solvent residue, safe extraction process, no pollution and low production cost, can be used for large-scale production, and greatly reduces the environmental protection pressure and the production cost. In the process of examples 1 to 3, the inventors performed chromatographic analysis of the CBD component-containing raw material obtained in each stage of example 1, taking example 1 as an example, and compared the raw material with the chromatogram of the CBD standard, and the chromatogram analysis in each stage of example 1 was as follows:

as can be seen from FIG. 1, the crude extract obtained in example 1 contains a large amount of CBDA, and the crude extract contains a large amount of impurities, which do not meet the requirement of high purity of CBD.

As can be seen from FIG. 2, the light fraction extracted in example 1 has a low content of CBDA, the content of CBD is increased, the main impurity in the crude extract is THC, and most of CBDA in the crude extract is decarboxylation transformed.

As can be seen from FIG. 3, the CBD oil extracted in example 1 has a significantly reduced CBDA content, and the CBD oil after separation does not contain THC, but the CBD purity in the CBD oil is relatively low, and still does not meet the requirement of high CBD purity.

As can be seen from FIG. 4, the CBD crystal extracted in example 1 no longer contains CBDA, and the CBD content in the CBD crystal is high, thus meeting the requirement of high purity CBD.

In conclusion, from the chromatographic analysis of the CBD crystals obtained in example 1 and the CBD standard, it is clear that the purity of CBD in the CBD crystals is equivalent to that of the standard, and it is also confirmed that the purification method of the present invention is highly efficient and feasible.