Separation and purification method for preparing pericarpium citri reticulatae essential oil

Abstract

The application discloses a separation and purification method for preparing pericarpium citri reticulatae essential oil, and relates to the technical field of pericarpium citri reticulatae essential oil preparation.The system comprises the following steps: S1, filtering pericarpium citri reticulatae crude essential oil through microporous filtration to remove solid suspensions and obtain pretreated essential oil; the application first completes impurity removal, dewaxing and preliminary classification of terpenes through three-stage dynamic molecular distillation, reduces the interference of impurities on subsequent adsorption, then realizes specific adsorption of target components through a D-limonene template molecular imprinting column, and combines supercritical CO2 green desorption to realize accurate separation and directional enrichment of pericarpium citri reticulatae essential oil, effectively solves the problems of non-selectivity of traditional distillation, low adsorption efficiency and difficulty in separating structure-similar terpenes, significantly improves the purity of target components, completely removes wax, pigments and isomer impurities, retains the natural activity and aromatic quality of essential oil, the desorption process has no organic solvent residue, the process has strong adaptability, and can meet the differentiated needs of high-end food, medicine and daily chemicals.

Description

Technical Field

[0001] This invention relates to the field of tangerine peel essential oil preparation technology, specifically to a separation and purification method for tangerine peel essential oil preparation. Background Technology

[0002] Dried tangerine peel (Chenpi) is the dried, mature peel of the citrus fruit (Citrus reticulata) and its cultivated varieties, belonging to the Rutaceae family. It is a traditional Chinese medicinal material used in both food and medicine, mainly produced in Xinhui, Guangdong, Sichuan, and Fujian provinces. Rich in volatile oils, flavonoids, polysaccharides, and other active ingredients, it is widely used in food flavoring, pharmaceuticals, health products, and daily skincare. Chenpi essential oil is the core volatile active substance extracted from dried tangerine peel. Its main components are D-limonene, terpenes, and alcohols, possessing antibacterial, antioxidant, qi-regulating, spleen-strengthening, and aromatic flavoring functions. It is a core raw material for high-end fragrances, natural medicines, and functional foods. Developing high-purity Chenpi essential oil is of significant industrial importance for improving the utilization rate of Chenpi resources and increasing product added value. The separation and purification of Chenpi essential oil is a crucial step in determining its quality and application scenarios. Crude essential oils often contain impurities such as water, waxes, pigments, and structurally similar terpenes, which not only reduce the purity and aroma quality of the essential oil but also affect its biological activity stability. Therefore, efficient and precise separation and purification technology is the core support for the industrialization of Chenpi essential oil.

[0003] However, existing purification technologies for tangerine peel essential oil still have certain shortcomings. Most existing tangerine peel essential oil purification methods use single molecular distillation technology, which can only achieve preliminary separation based on molecular weight and cannot selectively enrich terpenoid compounds with similar structures. When using molecular imprinted adsorption technology alone, a large number of impurities in the crude essential oil will interfere with the binding of adsorption sites, resulting in low adsorption efficiency and poor separation accuracy. The combined process of the two is lacking, and has shortcomings such as insufficient purity of target components, inability to directionally enrich, incomplete removal of impurities, and poor industrial adaptability, making it difficult to meet the quality requirements of high-end applications for tangerine peel essential oil. Therefore, it is of great significance to develop a separation and purification method for the preparation of tangerine peel essential oil. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a separation and purification method for the preparation of tangerine peel essential oil. This method first completes impurity removal, dewaxing, and preliminary terpene classification through three-stage dynamic molecular distillation, reducing the interference of impurities on subsequent adsorption. Then, the target component is specifically adsorbed using a D-limonene template molecular imprinted column, combined with supercritical CO2 green desorption, achieving precise separation and directional enrichment of tangerine peel essential oil. This solves the problems of non-selectivity, low adsorption efficiency, and difficulty in separating structurally similar terpenes in traditional distillation, improving the purity of the target component, removing waxes, pigments, and isomers, preserving the natural activity and aromatic quality of the essential oil, leaving no organic solvent residue during the desorption process, and exhibiting strong process adaptability.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a separation and purification method for the preparation of tangerine peel essential oil, the method comprising the following steps:

[0006] S1. The crude essential oil extracted from dried tangerine peel is filtered through a micropore to remove solid suspended matter, thus obtaining pretreated essential oil;

[0007] S2. The pretreated essential oil is passed into a three-stage series dynamic molecular distillation apparatus. The first stage distillation temperature is 50℃ and the pressure is 0.1Pa to remove low-boiling-point impurities and water. The second stage distillation temperature is 80℃ and the pressure is 0.01Pa to separate high-boiling-point waxes and pigments. The third stage distillation temperature gradient is 90-120℃, the pressure is 0.005-0.01Pa, and the rotor speed is 300-500rpm to obtain graded essential oil fractions.

[0008] S3. Pass the fractionated essential oil fractions into a molecularly imprinted polymer adsorption column with D-limonene as the template molecule for selective adsorption.

[0009] S4. The adsorption column was desorbed using supercritical CO2 at a pressure of 8-10 MPa and a temperature of 40℃. The desorbed essential oil components were collected.

[0010] S5. The desorbed essential oil components are vacuum dried and sterile filtered to obtain high-purity tangerine peel essential oil.

[0011] Furthermore, the microporous filtration in S1 uses a polytetrafluoroethylene microporous filter membrane with a pore size of 0.45 μm. The filtration process adopts a positive pressure filtration method, with the filtration pressure controlled at 0.2-0.3 MPa and the filtration temperature maintained at 20-25℃. The crude tangerine peel extract flows through the surface of the filter membrane at a uniform speed. Before use, the filter membrane is soaked and cleaned with anhydrous ethanol, then rinsed with deionized water until neutral. After cleaning, it is dried at 60℃ for 30 minutes.

[0012] Furthermore, in S2, the feed rate of the pretreated essential oil in the first-stage distillation is 10-15 mL / min, the scraping speed inside the distillation device is 200-250 rpm, the condensation temperature of the first-stage distillation is controlled at 5-10℃, the light components after distillation are collected into a special container through a condenser, and the heavy components are directly conveyed to the feed inlet of the second-stage distillation device. The residence time of the material in the first-stage distillation device is 1-2 min.

[0013] Furthermore, in S2, the feed rate of the secondary distillation is 8-12 mL / min, the internal scraping speed of the distillation device is 250-300 rpm, the condensation temperature of the secondary distillation is controlled at 0-5℃, the wax and pigment separated by distillation are deposited on the inner wall of the distillation device and discharged through the periodic slag discharge port, and the intermediate components after secondary distillation are directly transported to the feed end of the tertiary distillation device, and the residence time of the material in the secondary distillation device is 2-3 min.

[0014] Furthermore, in S2, the three-stage distillation uses a programmed heating method to control the temperature gradient, with a heating rate of 1℃ / min. The rotor speed is adjusted in real time by a variable frequency motor with an adjustment accuracy of ±5rpm. The three-stage distillation is collected in segments according to the order of fraction outflow, with a collection volume of 50mL for each segment. After collection, the fractions are sealed and stored at a temperature controlled at 10-15℃. The residence time of the material in the three-stage distillation apparatus is 3-5min.

[0015] Furthermore, the molecularly imprinted polymer in S3 is prepared by bulk polymerization. The raw materials include template molecule D-limonene, functional monomer methacrylic acid, crosslinking agent ethylene glycol dimethacrylate, initiator azobisisobutyronitrile, and solvent acetonitrile. The molar ratio of each raw material is 1:4:20:0.5:50. The polymerization reaction temperature is 60℃ and the polymerization reaction time is 24h. After the reaction is completed, the template molecule is removed by Soxhlet extraction and then vacuum dried to obtain the molecularly imprinted polymer.

[0016] Furthermore, in S3, the molecularly imprinted polymer adsorption column has a diameter of 20 mm, a length of 500 mm, and a packing density of 0.8 g / cm³. 3 The column adsorption flow rate for fractionated essential oil fractions was 1-3 mL / min, the adsorption temperature was controlled at 25℃, and the column temperature was maintained by a constant temperature circulating water jacket during the adsorption process. After adsorption, the adsorption column was rinsed with acetonitrile at a flow rate of 1 mL / min for 10 min.

[0017] Furthermore, in S4, the CO2 flow rate of supercritical CO2 desorption is 5-8 L / min, the desorption time is 30-40 min, the desorbed mixed fluid enters the separation vessel, the pressure of the separation vessel is controlled at 4-5 MPa, the separation temperature is controlled at 30℃, the separated CO2 is condensed and compressed and then recycled, and the desorbed essential oil components are collected through the bottom outlet of the separation vessel, and the collection container is made of light-proof and sealed material.

[0018] Furthermore, in S5, the vacuum drying temperature is controlled at 35-40℃, the vacuum degree is controlled at 0.08-0.09MPa, the drying time is 2-3h, the drying process adopts low-speed stirring with a stirring speed of 30-50rpm, the inner wall of the drying equipment is polished, and after drying, the material is transported to the sterile filtration equipment through a closed pipeline.

[0019] Furthermore, in S5, the aseptic filtration uses a polyethersulfone aseptic filter membrane with a pore size of 0.22 μm. The filtration pressure is controlled at 0.1-0.2 MPa, and the filtration operation is carried out in a Class 10,000 cleanroom environment. The filtered high-purity tangerine peel essential oil is directly transported to a sterile storage tank, which is filled with nitrogen for protection. The nitrogen purity is 99.99%, and the storage temperature is controlled at 5-10℃.

[0020] Compared with existing technologies, this separation and purification method for preparing tangerine peel essential oil has the following advantages:

[0021] This invention utilizes a three-stage dynamic molecular distillation process to first remove impurities, dewax, and perform preliminary terpene fractionation, reducing interference from impurities on subsequent adsorption. Then, a D-limonene template molecularly imprinted column is used to achieve specific adsorption of the target components. Combined with supercritical CO2 green desorption, this enables precise separation and targeted enrichment of tangerine peel essential oil. This effectively solves the problems of non-selectivity, low adsorption efficiency, and difficulty in separating structurally similar terpenes in traditional distillation, significantly improving the purity of the target components, thoroughly removing waxes, pigments, and isomers, and preserving the natural activity and aroma of the essential oil. The desorption process leaves no organic solvent residue, and the process is highly adaptable, meeting the differentiated needs of high-end food, pharmaceutical, and daily chemical industries, and greatly enhancing the added value and industrial application potential of tangerine peel essential oil.

[0022] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0024] Figure 1 A flowchart of a separation and purification method for preparing tangerine peel essential oil;

[0025] Figure 2This is a flowchart of a separation and purification method for preparing tangerine peel essential oil. Detailed Implementation

[0026] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0027] This invention provides a separation and purification method for the preparation of tangerine peel essential oil. Addressing the problems of non-selectivity distillation, low adsorption efficiency, difficulty in separating structurally similar terpenes, and incomplete removal of impurities in traditional purification techniques, this invention innovatively employs a three-stage dynamic molecular distillation, D-limonene template molecular imprinted adsorption, and supercritical CO2 desorption process to achieve precise separation and targeted enrichment of tangerine peel essential oil. The high-purity product prepared can meet the differentiated application needs of high-end food, pharmaceutical, and daily chemical fields.

[0028] See Figure 1 and Figure 2 The core process of this technical solution consists of the following five steps:

[0029] The first step is microporous filtration pretreatment. The crude tangerine peel essential oil is filtered under positive pressure through a 0.45μm polytetrafluoroethylene microporous filter membrane. The filtration pressure is controlled at 0.2-0.3MPa and the temperature is maintained at 20-25℃. Before use, the filter membrane is cleaned with ethanol, rinsed with deionized water and dried at 60℃ to remove solid suspended matter and obtain pretreated essential oil.

[0030] The second step is a three-stage tandem dynamic molecular distillation. The first stage distillation is set at a temperature of 50℃ and a pressure of 0.1Pa to remove low-boiling-point impurities and water. The second stage distillation is set at a temperature of 80℃ and a pressure of 0.01Pa to separate high-boiling-point waxes and pigments. The third stage distillation uses a programmed temperature rise of 90-120℃ at a rate of 1℃ / min and a rotor speed of 300-500rpm. The fractions are collected in stages to complete the removal of impurities, dewaxing, and preliminary terpene fractionation, reducing interference from subsequent adsorption.

[0031] The third step is molecularly imprinted selective adsorption. Using D-limonene as a template molecule, a molecularly imprinted polymer is prepared by bulk polymerization and packed into a special adsorption column. Fractionated essential oil fractions are loaded onto the column at a flow rate of 1-3 mL / min and specific adsorption is completed under a constant temperature of 25℃. After adsorption, non-target impurities are removed by acetonitrile washing.

[0032] The fourth step is supercritical CO2 green desorption, in which the saturated column is desorbed at a pressure of 8-10 MPa and a temperature of 40°C, with a CO2 flow rate of 5-8 L / min. After desorption, the mixed fluid enters the separation vessel for separation, and the CO2 is recycled. The desorbed essential oil components are collected, and there is no organic solvent residue throughout the process.

[0033] The fifth step is vacuum drying and sterile filtration. The desorbed components are dried at 35-40℃ and 0.08-0.09MPa vacuum for 2-3 hours, then filtered through a 0.22μm polyethersulfone sterile filter membrane, and finally stored under nitrogen protection at 5-10℃ to obtain high-purity tangerine peel essential oil.

[0034] This solution combines multi-stage distillation pretreatment with specific adsorption to thoroughly remove waxes, pigments, and isomers, significantly improving the purity of the target components while preserving the natural activity and aroma of the essential oil. The process is green, efficient, and highly adaptable to industrial applications, greatly enhancing the added value of tangerine peel essential oil.

[0035] Example 1

[0036] This embodiment employs a patented optimal combination of process parameters. Essential oil pretreatment is achieved through microporous filtration, followed by impurity removal, dewaxing, and preliminary terpene classification via three-stage tandem dynamic molecular distillation. Target component specific enrichment is achieved using a D-limonene molecularly imprinted adsorption column, and impurities are removed via supercritical CO2 green desorption. Finally, high-purity tangerine peel essential oil is obtained through vacuum drying and aseptic filtration. This method thoroughly removes waxy pigments and terpene isomers, leaving no organic solvent residue, maximizing the preservation of the essential oil's natural activity and aromatic quality, and meeting high-end application standards.

[0037] See Figure 1 and Figure 2 The specific implementation process of this embodiment is as follows:

[0038] Microporous filtration pretreatment: A polytetrafluoroethylene microporous filter membrane with a pore size of 0.45 μm was selected. The filter membrane was first soaked and cleaned with anhydrous ethanol, then rinsed with deionized water until neutral, and subsequently dried at 60℃ for 30 min. Positive pressure filtration was used, with the filtration pressure controlled at 0.25 MPa and the filtration temperature maintained at 22℃. The crude tangerine peel extract essential oil was flowed uniformly through the surface of the filter membrane to remove solid suspended matter, thus obtaining the pretreated essential oil.

[0039] Three-stage tandem dynamic molecular distillation: The first-stage distillation temperature was set at 50℃, pressure at 0.1 Pa, pretreated essential oil feed rate at 12 mL / min, scraper rotation speed at 220 rpm, and condensation temperature at 7℃. The material remained in the first-stage distillation unit for 1.5 min to remove low-boiling-point impurities and moisture. The second-stage distillation temperature was set at 80℃, pressure at 0.01 Pa, feed rate at 10 mL / min, scraper rotation speed at 270 rpm, and condensation temperature at 3℃. The material remained in the second-stage distillation unit for 2.5 min to separate high-boiling-point waxes and pigments. The third-stage distillation used a programmed temperature rise of 90-120℃ at a rate of 1℃ / min, with a rotor speed of 400 rpm. The material remained in the third-stage distillation unit for 4 min, and was collected in fractions according to the order of distillate outflow, with each fraction having a collection volume of 50 mL. After collection, the fractions were sealed and stored at 12℃ to obtain graded essential oil fractions.

[0040] Molecularly imprinted specific adsorption: Molecularly imprinted polymers were prepared by bulk polymerization. The raw materials were template molecule D-limonene, functional monomer methacrylic acid, crosslinking agent ethylene glycol dimethacrylate, initiator azobisisobutyronitrile, and solvent acetonitrile, with a molar ratio of 1:4:20:0.5:50. The polymerization reaction temperature was 60℃, and the reaction time was 24 h. After the reaction, the template molecule was removed by Soxhlet extraction, and the polymer was obtained by vacuum drying. The polymer was packed into an adsorption column with a diameter of 20 mm and a length of 500 mm at a packing density of 0.8 g / cm³. 3 The fractionated essential oil fractions were loaded onto the column for adsorption at a flow rate of 2 mL / min. The adsorption temperature was controlled at 25℃ and maintained by a constant temperature circulating water jacket. After adsorption, the adsorption column was washed with acetonitrile at a flow rate of 1 mL / min for 10 min.

[0041] Supercritical CO2 desorption: The desorption pressure was set at 9 MPa, the temperature at 40℃, the CO2 flow rate at 6 L / min, and the desorption time at 35 min. The desorbed mixed fluid entered the separation vessel, where the pressure was controlled at 4.5 MPa and the separation temperature at 30℃. The separated CO2 was condensed, compressed, and recycled. The desorbed essential oil components were collected through the bottom outlet of the separation vessel.

[0042] Vacuum drying and aseptic filtration: The desorbed essential oil components were vacuum dried for 2.5 hours at 37℃ and a vacuum degree of 0.085MPa, with low-speed stirring at 40rpm during the drying process. After drying, the material was transported to an aseptic filtration device through a closed pipeline and filtered using a 0.22μm pore size polyethersulfone aseptic filter membrane at a filtration pressure controlled at 0.15MPa. The filtered high-purity tangerine peel essential oil was then transferred to an aseptic storage tank, which was filled with nitrogen for protection, and the storage temperature was controlled at 5℃.

[0043] In summary, the high-purity tangerine peel essential oil prepared in this embodiment achieved a D-limonene purity of 98.5%, a wax and pigment removal rate of 99.2%, a terpene isomer removal rate of 97.8%, no organic solvent residue, and a natural aromatic activity retention rate of 99.0%. This essential oil can be directly applied in high-end food, pharmaceutical, and daily chemical fields, achieving optimal purification effect and quality performance.

[0044] Example 2

[0045] This embodiment fine-tunes the three-stage distillation temperature gradient and supercritical desorption parameters, optimizing material flow rate and processing time while retaining the core patented combined process. This improves the efficiency of continuous industrial production and reduces process energy consumption. The prepared tangerine peel essential oil maintains high purity and excellent quality, meeting the high-end application requirements of large-scale production, balancing production efficiency and product quality.

[0046] See Figure 1 and Figure 2 The specific implementation process of this embodiment is as follows:

[0047] Microporous filtration pretreatment: A polytetrafluoroethylene microporous filter membrane with a pore size of 0.45 μm was selected. The filter membrane was first soaked and cleaned with anhydrous ethanol, then rinsed with deionized water until neutral, and subsequently dried at 60℃ for 30 min. Positive pressure filtration was used, with the filtration pressure controlled at 0.2 MPa and the filtration temperature maintained at 25℃. The crude tangerine peel extract essential oil was flowed uniformly through the surface of the filter membrane to remove solid suspended matter, thus obtaining the pretreated essential oil.

[0048] Three-stage tandem dynamic molecular distillation: The first-stage distillation temperature was set at 50℃, pressure at 0.1 Pa, pretreated essential oil feed rate at 12 mL / min, scraper rotation speed at 220 rpm, and condensation temperature at 7℃. The material remained in the first-stage distillation unit for 1.5 min to remove low-boiling-point impurities and moisture. The second-stage distillation temperature was set at 80℃, pressure at 0.01 Pa, feed rate at 10 mL / min, scraper rotation speed at 270 rpm, and condensation temperature at 3℃. The material remained in the second-stage distillation unit for 2.5 min to separate high-boiling-point waxes and pigments. The third-stage distillation used a programmed temperature rise of 95-115℃ at a rate of 1℃ / min, with a rotor speed of 350 rpm. The material remained in the third-stage distillation unit for 3.5 min, and was collected in fractions according to the order of distillate outflow, with each fraction having a collection volume of 50 mL. After collection, the fractions were sealed and stored at 12℃ to obtain graded essential oil fractions.

[0049] Molecularly imprinted specific adsorption: Molecularly imprinted polymers were prepared by bulk polymerization. The raw materials were template molecule D-limonene, functional monomer methacrylic acid, crosslinking agent ethylene glycol dimethacrylate, initiator azobisisobutyronitrile, and solvent acetonitrile, with a molar ratio of 1:4:20:0.5:50. The polymerization reaction temperature was 60℃, and the reaction time was 24 h. After the reaction, the template molecule was removed by Soxhlet extraction, and the polymer was obtained by vacuum drying. The polymer was packed into an adsorption column with a diameter of 20 mm and a length of 500 mm at a packing density of 0.8 g / cm³. 3 The fractionated essential oil fractions were loaded onto the column for adsorption at a flow rate of 3 mL / min. The adsorption temperature was controlled at 25℃ and maintained by a constant temperature circulating water jacket. After adsorption, the adsorption column was washed with acetonitrile at a flow rate of 1 mL / min for 10 min.

[0050] Supercritical CO2 desorption: The desorption pressure was set at 8 MPa, the temperature at 40℃, the CO2 flow rate at 5 L / min, and the desorption time at 30 min. The desorbed mixed fluid entered the separation vessel, where the pressure was controlled at 4.5 MPa and the separation temperature at 30℃. The separated CO2 was condensed, compressed, and recycled. The desorbed essential oil components were collected through the bottom outlet of the separation vessel.

[0051] Vacuum drying and aseptic filtration: The desorbed essential oil components were vacuum dried for 3 hours at 40℃ and a vacuum degree of 0.09MPa, with low-speed stirring at 40rpm during the drying process. After drying, the material was transported to an aseptic filtration device through a closed pipeline and filtered using a 0.22μm pore size polyethersulfone aseptic filter membrane at a filtration pressure controlled at 0.15MPa. The filtered high-purity tangerine peel essential oil was then transferred to an aseptic storage tank, which was filled with nitrogen for protection, and the storage temperature was controlled at 5℃.

[0052] In summary, the tangerine peel essential oil prepared in this embodiment has a D-limonene purity of 97.8%, a wax removal rate of 98.5%, a terpene isomer removal rate of 96.3%, no organic solvent residue, and a natural activity retention rate of 98.2%. Compared with Example 1, the material processing efficiency is improved by 10%, the process energy consumption is reduced by 8%, the adaptability for industrial mass production is significantly improved, and the product quality still meets the requirements of high-end applications.

[0053] Example 3

[0054] This embodiment employs lower process temperatures and gentler stirring parameters to reduce the heat and mechanical shear stress on the essential oils throughout the process, focusing on protecting the natural bioactivity and aromatic components of the tangerine peel essential oil. While ensuring the removal of impurities and the enrichment of components, it maximizes the preservation of the essential oil's medicinal and edible properties, making the prepared essential oil more suitable for the pharmaceutical and high-end skincare fields.

[0055] See Figure 1 and Figure 2 The specific implementation process of this embodiment is as follows:

[0056] Microporous filtration pretreatment: A polytetrafluoroethylene microporous filter membrane with a pore size of 0.45 μm was selected. The filter membrane was first soaked and cleaned with anhydrous ethanol, then rinsed with deionized water until neutral, and subsequently dried at 60℃ for 30 min. Positive pressure filtration was adopted, with the filtration pressure controlled at 0.3 MPa and the filtration temperature maintained at 20℃. The crude tangerine peel extract essential oil was flowed uniformly through the surface of the filter membrane to remove solid suspended matter, thus obtaining the pretreated essential oil.

[0057] Three-stage tandem dynamic molecular distillation: The first-stage distillation temperature was set at 50℃, pressure at 0.1 Pa, pretreated essential oil feed rate at 10 mL / min, scraper rotation speed at 220 rpm, and condensation temperature at 7℃. The material remained in the first-stage distillation unit for 1.5 min to remove low-boiling-point impurities and moisture. The second-stage distillation temperature was set at 80℃, pressure at 0.01 Pa, feed rate at 8 mL / min, scraper rotation speed at 270 rpm, and condensation temperature at 3℃. The material remained in the second-stage distillation unit for 2.5 min to separate high-boiling-point waxes and pigments. The third-stage distillation used a programmed temperature rise of 90-110℃ at a rate of 1℃ / min, with a rotor speed of 300 rpm. The material remained in the third-stage distillation unit for 5 min, and was collected in fractions according to the order of distillate outflow, with each fraction having a collection volume of 50 mL. After collection, the fractions were sealed and stored at 12℃ to obtain graded essential oil fractions.

[0058] Molecularly imprinted specific adsorption: Molecularly imprinted polymers were prepared by bulk polymerization. The raw materials were template molecule D-limonene, functional monomer methacrylic acid, crosslinking agent ethylene glycol dimethacrylate, initiator azobisisobutyronitrile, and solvent acetonitrile, with a molar ratio of 1:4:20:0.5:50. The polymerization reaction temperature was 60℃, and the reaction time was 24 h. After the reaction, the template molecule was removed by Soxhlet extraction, and the polymer was obtained by vacuum drying. The polymer was packed into an adsorption column with a diameter of 20 mm and a length of 500 mm at a packing density of 0.8 g / cm³. 3 The fractionated essential oil fractions were loaded onto the column for adsorption at a flow rate of 1 mL / min. The adsorption temperature was controlled at 25℃ and maintained by a constant temperature circulating water jacket. After adsorption, the adsorption column was washed with acetonitrile at a flow rate of 1 mL / min for 10 min.

[0059] Supercritical CO2 desorption: The desorption pressure was set at 9 MPa, the temperature at 40℃, the CO2 flow rate at 6 L / min, and the desorption time at 35 min. The desorbed mixed fluid entered the separation vessel, where the pressure was controlled at 4.5 MPa and the separation temperature at 30℃. The separated CO2 was condensed, compressed, and recycled. The desorbed essential oil components were collected through the bottom outlet of the separation vessel.

[0060] Vacuum drying and aseptic filtration: The desorbed essential oil components were vacuum dried for 2 hours at 35℃ and a vacuum degree of 0.08MPa, with low-speed stirring at 30rpm during the drying process. After drying, the material was transported to an aseptic filtration device through a closed pipeline and filtered using a 0.22μm pore size polyethersulfone aseptic filter membrane at a filtration pressure controlled at 0.15MPa. The filtered high-purity tangerine peel essential oil was then transferred to an aseptic storage tank, which was filled with nitrogen for protection, and the storage temperature was controlled at 8℃.

[0061] In summary, the tangerine peel essential oil prepared in this embodiment has a D-limonene purity of 98.2%, a wax removal rate of 99.0%, a terpene isomer removal rate of 97.5%, and no organic solvent residue. The essential oil retains 99.5% of its natural biological activity, with complete and undamaged aromatic components, demonstrating excellent performance in pharmaceutical and high-end skincare applications. Both its purification effect and activity retention capacity are at an excellent level.

[0062] Comparative Example

[0063] This comparative example employs a traditional tangerine peel essential oil purification process, using only two-stage molecular distillation for preliminary separation, without combining tertiary dynamic molecular distillation, molecularly imprinted specific adsorption, and supercritical CO2 desorption technologies. Ethanol is used as the elution solvent, and there is no aseptic post-treatment or nitrogen protection. This simulates conventional industry purification methods to compare and verify the superiority of this patented process. The specific implementation process of this comparative example is as follows:

[0064] Microporous filtration pretreatment: A polytetrafluoroethylene microporous filter membrane with a pore size of 0.45 μm was selected. The filter membrane was first soaked and cleaned with anhydrous ethanol, then rinsed with deionized water until neutral, and subsequently dried at 60℃ for 30 min. Positive pressure filtration was used, with the filtration pressure controlled at 0.25 MPa and the filtration temperature maintained at 22℃. The crude tangerine peel extract essential oil was flowed uniformly through the surface of the filter membrane to remove solid suspended matter, thus obtaining the pretreated essential oil.

[0065] Single-stage molecular distillation: The first-stage distillation temperature is set at 50℃, the pressure at 0.1Pa, the pretreated essential oil feed rate is 12mL / min, the scraper rotation speed inside the distillation apparatus is 220rpm, the condensation temperature is controlled at 7℃, and the material stays in the first-stage distillation apparatus for 1.5min to remove low-boiling-point impurities and moisture. The second-stage distillation temperature is set at 80℃, the pressure at 0.01Pa, the feed rate is 10mL / min, the scraper rotation speed is 270rpm, the condensation temperature is controlled at 3℃, and the material stays in the second-stage distillation apparatus for 2.5min to separate high-boiling-point waxes and pigments. The distilled essential oil is collected directly.

[0066] Traditional organic solvent elution: without using molecularly imprinted adsorption columns, ethanol is directly used to elute the distilled essential oils, and the eluted essential oil components are collected.

[0067] Routine post-processing: The eluted essential oil components were vacuum dried at 37°C and 0.085 MPa for 2.5 h. After drying, they were filtered through a regular filter membrane without sterilization or nitrogen protection to obtain purified tangerine peel essential oil.

[0068] In summary, the tangerine peel essential oil prepared using traditional purification processes in this comparative example had a D-limonene purity of only 82.3%, a wax and pigment removal rate of only 75.6%, ineffective separation of terpene isomers, residual ethanol organic solvents, and a natural activity retention rate of only 80.1%. Traditional processes can only achieve preliminary purification of essential oils, failing to achieve targeted enrichment of target components, resulting in incomplete impurity removal, limited product quality and application scope, and inability to meet the requirements of high-end applications.

[0069] Comparison Projects Example 1 Example 2 Example 3 Comparative Example core technology <![CDATA[Three-stage distillation + Molecular imprinting + Supercritical CO2]]> <![CDATA[Three-stage distillation + Molecular imprinting + Supercritical CO2]]> <![CDATA[Three-stage distillation + Molecular imprinting + Supercritical CO2]]> Single two-stage distillation + ethanol elution D-Limonene Purity 98.50% 97.80% 98.20% 82.30% Wax pigment removal rate 99.20% 98.50% 99.00% 75.60% Organic solvent residue none none none have Natural activity retention rate 99.00% 98.20% 99.50% 80.10% Overall Performance Rating excellent good excellent Difference

[0070] As can be seen from the comparison table above, all three embodiments of this patent employ a combined process of three-stage dynamic molecular distillation, molecularly imprinted specific adsorption, and supercritical CO2 green desorption. In terms of core indicators such as component purity, impurity removal, absence of solvent residue, and retention of natural activity, they are far superior to the comparative examples using traditional processes. Example 1 has the optimal parameters and the best overall purification effect; Example 2 optimizes production parameters to suit industrial-scale production; Example 3 uses a gentle process to maximize the retention of the essential oil's natural activity. The traditional processes in the comparative examples suffer from defects such as non-selective separation, incomplete impurity removal, and solvent residue, resulting in poor product quality. This patented process effectively solves the pain points of traditional purification technologies, meeting the differentiated needs of high-end food, pharmaceutical, and daily chemical industries, and possesses significant technological advantages and industrialization value.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A separation and purification method for preparing tangerine peel essential oil, characterized in that, The method includes the following steps: S1. The crude essential oil extracted from dried tangerine peel is filtered through a micropore to remove solid suspended matter, thus obtaining pretreated essential oil; S2. The pretreated essential oil is passed into a three-stage series dynamic molecular distillation apparatus. The first stage distillation temperature is 50℃ and the pressure is 0.1Pa to remove low-boiling-point impurities and water. The second stage distillation temperature is 80℃ and the pressure is 0.01Pa to separate high-boiling-point waxes and pigments. The third stage distillation temperature gradient is 90-120℃, the pressure is 0.005-0.01Pa, and the rotor speed is 300-500rpm to obtain graded essential oil fractions. S3. Pass the fractionated essential oil fractions into a molecularly imprinted polymer adsorption column with D-limonene as the template molecule for selective adsorption. S4. The adsorption column was desorbed using supercritical CO2 at a pressure of 8-10 MPa and a temperature of 40℃. The desorbed essential oil components were collected. S5. The desorbed essential oil components are vacuum dried and sterile filtered to obtain high-purity tangerine peel essential oil.

2. The separation and purification method for preparing tangerine peel essential oil according to claim 1, characterized in that, The microporous filtration in S1 uses a polytetrafluoroethylene microporous membrane with a pore size of 0.45 μm. The filtration process adopts a positive pressure filtration method, with the filtration pressure controlled at 0.2-0.3 MPa and the filtration temperature maintained at 20-25℃. The crude tangerine peel extract flows through the surface of the membrane at a uniform speed. Before use, the membrane is soaked and cleaned with anhydrous ethanol, then rinsed with deionized water until neutral. After cleaning, it is dried at 60℃ for 30 minutes.

3. The separation and purification method for preparing tangerine peel essential oil according to claim 1, characterized in that, In S2, the feed rate of the pretreated essential oil for the first-stage distillation is 10-15 mL / min, the scraper rotation speed inside the distillation device is 200-250 rpm, the condensation temperature of the first-stage distillation is controlled at 5-10℃, the light components after distillation are collected in a special container through a condenser tube, and the heavy components are directly conveyed to the feed inlet of the second-stage distillation device. The residence time of the material in the first-stage distillation device is 1-2 min.

4. The separation and purification method for preparing tangerine peel essential oil according to claim 1, characterized in that, The feed rate of the secondary distillation in S2 is 8-12 mL / min, the scraper rotation speed inside the distillation device is 250-300 rpm, the condensation temperature of the secondary distillation is controlled at 0-5℃, the wax and pigment separated by distillation are deposited on the inner wall of the distillation device and discharged through the periodic slag discharge port, and the intermediate components after secondary distillation are directly transported to the feed end of the tertiary distillation device, and the residence time of the material in the secondary distillation device is 2-3 min.

5. The separation and purification method for preparing tangerine peel essential oil according to claim 1, characterized in that, In S2, the three-stage distillation uses a programmed heating method to control the temperature gradient, with a heating rate of 1℃ / min. The rotor speed is adjusted in real time by a variable frequency motor with an adjustment accuracy of ±5rpm. The three-stage distillation is collected in segments according to the order of fraction outflow, with a collection volume of 50mL for each segment. After collection, the fractions are sealed and stored at a temperature controlled at 10-15℃. The residence time of the material in the three-stage distillation apparatus is 3-5min.

6. The separation and purification method for preparing tangerine peel essential oil according to claim 1, characterized in that, The molecularly imprinted polymer in S3 is prepared by bulk polymerization. The raw materials include template molecule D-limonene, functional monomer methacrylic acid, crosslinking agent ethylene glycol dimethacrylate, initiator azobisisobutyronitrile, and solvent acetonitrile. The molar ratio of each raw material is 1:4:20:0.5:

50. The polymerization reaction temperature is 60℃ and the polymerization reaction time is 24h. After the reaction is completed, the template molecule is removed by Soxhlet extraction and then vacuum drying is performed to obtain the molecularly imprinted polymer.

7. The separation and purification method for preparing tangerine peel essential oil according to claim 1, characterized in that, The molecularly imprinted polymer adsorption column in S3 has a diameter of 20 mm, a length of 500 mm, and a packing density of 0.8 g / cm³. 3 The column adsorption flow rate for fractionated essential oil fractions was 1-3 mL / min, the adsorption temperature was controlled at 25℃, and the column temperature was maintained by a constant temperature circulating water jacket during the adsorption process. After adsorption, the adsorption column was rinsed with acetonitrile at a flow rate of 1 mL / min for 10 min.

8. The separation and purification method for preparing tangerine peel essential oil according to claim 1, characterized in that, In S4, the CO2 flow rate for supercritical CO2 desorption is 5-8 L / min, the desorption time is 30-40 min, the desorbed mixed fluid enters the separation vessel, the pressure of the separation vessel is controlled at 4-5 MPa, the separation temperature is controlled at 30℃, the separated CO2 is condensed and compressed and then recycled, and the desorbed essential oil components are collected through the bottom outlet of the separation vessel.

9. The separation and purification method for preparing tangerine peel essential oil according to claim 1, characterized in that, In the S5 process, the vacuum drying temperature is controlled at 35-40℃, the vacuum degree is controlled at 0.08-0.09MPa, the drying time is 2-3h, the drying process adopts low-speed stirring, the stirring speed is 30-50rpm, and after drying, the material is transported to the sterile filtration equipment through a closed pipeline.

10. The separation and purification method for preparing tangerine peel essential oil according to claim 1, characterized in that, The aseptic filtration in S5 uses a polyethersulfone aseptic filter membrane with a pore size of 0.22μm and a filtration pressure controlled at 0.1-0.2MPa. The filtered high-purity tangerine peel essential oil is directly transported to an aseptic storage tank, which is filled with nitrogen for protection and the storage temperature is controlled at 5-10℃.

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