Chitosan-ionic liquid-zein microspheres as well as preparation method and application thereof

Abstract

The invention discloses a chitosan-ionic liquid-zein microsphere as well as a preparation method and application thereof, and relates to the technical field of adsorption material preparation, the surface of the microsphere has a gully structure, and the raw materials of the microsphere comprise an acid solvent, a zein / chitosan mixture, an emulsifier, plant essential oil, ionic liquid and glutaraldehyde. According to the preparation method of the microspheres, plant essential oil and ionic liquid are taken as the core of molecular recognition, the dosage and adding mode of a mixed emulsifier are adjusted, zein, chitosan and glutaraldehyde are taken as the skeleton, and a material which has good adsorption performance and is used for adsorbing specific plant essential oil is prepared. The chitosan-ionic liquid-zein microspheres are obtained by the steps of preparing the chitosan-ionic liquid-zein microspheres. The chitosan-ionic liquid-zein microspheres disclosed by the invention have relatively high selectivity and absorptivity on specific plant essential oil, and can be used for adsorbing and concentrating the specific plant essential oil in a low-concentration environment, so that the utilization rate of the plant essential oil is increased.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of adsorption materials, and in particular to chitosan-ionic liquid-zein microspheres and a preparation method and application thereof. Background Art

[0002] Steam distillation is one of the common methods for producing plant essential oils. At present, steam distillation is the most widely used method, with simple equipment, convenient operation, no solvent residue, low cost, easy to promote, strong practicality, good stability, and relatively mature technology, equipment and operation. When plant materials are distilled by steam, plant essential oils will be distilled out together with water vapor, and after condensation, the plant essential oils can be obtained by separating the oil and water phases. However, the condensate obtained after condensation is mainly composed of water, and the amount of plant essential oils is much less than water. A small amount of essential oil droplets are suspended in the condensate to form oil droplets with a particle size of less than 0.1 microns. Because of its increased solubility in water, it cannot be used by the oil-water two-phase separation method.

[0003] Adsorption is another common method for producing plant essential oils. The adsorption method uses the interaction between chemical substances and adsorbents to combine with adsorbents, thereby achieving the purpose of separation and purification from raw materials. The selection of adsorbents is key. Excellent adsorbents have the advantages of good selectivity, stable physical and chemical properties, simple operation and easy regeneration. Traditional adsorbents commonly use animal and plant oils, silica gel, activated carbon, etc., but their disadvantage is that they are not selective in the adsorption of plant essential oils. They just use the similar hydrophilic and hydrophobic properties between the adsorbent and the plant essential oils to adsorb all essential oil molecules indiscriminately. The essential oil adsorption in the prior art has a low adsorption rate and poor selectivity during the adsorption process. Some unwanted impurities may be extracted, resulting in a low purity of the extract. Summary of the invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, provide a chitosan-ionic liquid-zein microsphere and a preparation method and application thereof, and solve the technical problems of poor selectivity and low adsorption rate of specific plant essential oils in the process of plant essential oil adsorption in the prior art.

[0005] To achieve the above technical purpose, the technical solution of the present invention provides a chitosan-ionic liquid-zein microsphere, the surface of the chitosan-ionic liquid-zein microsphere has a groove structure, and its raw materials include 50 parts of acidic solvent, 1.02 parts to 2 parts of zein / chitosan mixture, 2.05 parts to 9.5 parts of emulsifier, 0.5 parts to 1.5 parts of plant essential oil, 0.1 parts to 1.5 parts of ionic liquid and 0.001 parts to 0.45 parts of glutaraldehyde in parts by mass.

[0006] Preferably, the mass ratio of zein powder to chitosan powder in the zein / chitosan mixture is 1:(0.02-1).

[0007] Preferably, the emulsifier is prepared by mixing Tween 20, n-heptane and ethyl acetate in a mass ratio of 1:(0.05-0.8):(1-3).

[0008] Preferably, the plant essential oil is one or both of lemon essential oil and pine needle essential oil.

[0009] Preferably, the ionic liquid is one or more of 1-pentyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-heptyl-3-methylimidazolium chloride and 1-octyl-3-methylimidazolium chloride.

[0010] Preferably, the ionic liquid is a mixture of 1-pentyl-3-methylimidazolium chloride and 1-hexyl-3-methylimidazolium chloride.

[0011] A method for preparing chitosan-ionic liquid-zein microspheres based on the above-mentioned method comprises the following steps:

[0012] S1, adding glacial acetic acid to an ethanol aqueous solution to obtain an acidic solvent, and separating the acidic solvent into an acidic solvent A and an acidic solvent B;

[0013] S2, dissolving zein powder and chitosan powder in the acidic solvent A to obtain a mixed solution C;

[0014] S3, dissolving the emulsifier in the acidic solvent B, adding the plant essential oil and the ionic liquid after stirring evenly, and continuing to stir to obtain a mixed solution D;

[0015] The functions of this step are: first, by adjusting the ratio of Tween 20, n-heptane and ethyl acetate, the size of the emulsifier particles is controlled; second, the ionic liquid is added to form a synergistic interface force with the emulsifier to assist in forming a good microsphere structure; third, the arrangement of the functional groups of zein, chitosan and ionic liquid is adjusted through the spatial structure of plant essential oil molecules and the arrangement order of functional groups to enhance the molecular recognition effect.

[0016] S4, dropping the mixed solution C into the mixed solution D, stirring continuously at 400 rpm for 30 min, to obtain a mixed solution E, so that the particle size of the chitosan-ionic liquid-zein microspheres can be stabilized at 400 μm, and the surface has a regular groove structure;

[0017] S5, dropping glutaraldehyde into the mixed solution E at a rate of 0.05-1 mL / min, and continuously stirring at a speed of 400 rpm for 150 min to obtain a mixed solution F;

[0018] S6. The mixed solution F is vacuum filtered, and the obtained filter cake is washed with ethanol and dried to obtain a light yellow powder, namely chitosan-ionic liquid-zein microspheres.

[0019] Preferably, S1 is specifically: V1 mL of 75% ethanol aqueous solution is mixed with V2 mL of glacial acetic acid to obtain an acidic solvent, V2 = V1*2%, and the acidic solvent is divided into an acidic solvent A and an acidic solvent B.

[0020] Preferably, the mass ratio of the acidic solvent A to the acidic solvent B in S1 is 0.2-5:1.

[0021] An application of the chitosan-ionic liquid-zein microspheres described above in the selective adsorption of terpene essential oils.

[0022] In the preparation process of the present invention, plant essential oil is added into a milky white mixed solution D as a template molecule, and the plant essential oil forms a composite system with a specific pore structure together with other components (such as ionic liquid and solvent); a mixed solution C (containing zein and chitosan) is slowly added into the mixed solution D (containing plant essential oil and ionic liquid) to form a milky yellow mixed solution E, and in this step, the functional components (zein and chitosan) are mixed with the template molecules (plant essential oil), and these components are evenly distributed by stirring to form a preliminary mixed system with potential imprinting ability; glutaraldehyde is added dropwise into the mixed solution E to carry out a cross-linking reaction, and glutaraldehyde, as a cross-linking agent, reacts with zein and chitosan to form a three-dimensional cross-linked network, and in the cross-linking process, the plant essential oil is embedded into the cross-linked network as a template molecule. The cross-linking reaction fixes the functional polymer in a specific spatial structure, and the template molecules (plant essential oils) are embedded in these structures; after vacuum filtration, the filter cake is rinsed with anhydrous ethanol. This process aims to remove uncross-linked substances and free template molecules, and at the same time remove the template molecules in the microsphere structure, so that the imprinted pores are exposed and can specifically bind to the target molecules (plant essential oils). After drying, a pore structure matching the template molecules is formed in the microspheres, and these pores have selective recognition and adsorption capabilities for specific plant essential oils.

[0023] In addition to providing a basic framework structure, zein and chitosan also contain a large number of hydroxyl and carbon ring structure functional groups in their molecules. The arrangement of the functional groups will be spontaneously adjusted during the preparation process due to the addition of ionic liquids and essential oil molecules. Molecular recognition of plant essential oils can be performed from multiple aspects such as spatial structure and intermolecular forces, thereby increasing the adsorption of essential oils on the framework structure.

[0024] The practical emulsifier in the present invention can form three-dimensional holes with a certain spatial size in the basic framework structure of zein / chitosan, which is close to the spatial size of plant essential oil molecules and is conducive to the molecular recognition process.

[0025] Ionic liquids and plant essential oil molecules form a miscible system to assist in forming a good microsphere structure; the ionic liquid molecules themselves contain long-chain alkanes, carbon ring structure functional groups and anions and cations, and the hydrophilicity / hydrophobicity and hydrogen bonds, π-π bonds, ionic bonds and other chemical bonds between them and plant essential oil molecules can greatly enhance the molecular recognition effect.

[0026] The lemon essential oil and pine needle essential oil used in the present invention contain a large amount of terpene substances such as α-pinene, β-pinene, β-myrcene, etc., so the prepared chitosan-ionic liquid-zein microspheres have good selectivity and high adsorption rate when adsorbing terpene essential oils.

[0027] Compared with the prior art, the beneficial effects of the present invention include:

[0028] Taking plant essential oils and ionic liquids as the core of molecular recognition, by adjusting the amount of mixed emulsifiers and the way of addition, a material with good adsorption performance for adsorbing specific plant essential oils was prepared with zein, chitosan and glutaraldehyde as the skeleton.

[0029] The lemon essential oil and pine needle essential oil used contain a large amount of terpenoids such as α-pinene, β-pinene, and β-myrcene; the ionic liquid used can form a specific spatial structure with plant essential oil molecules by utilizing hydrophilicity / hydrophobicity and chemical bonds such as hydrogen bonds, π-π bonds, and ionic bonds, and use the principles of molecular imprinting technology to identify plant essential oil molecules with similar structures.

[0030] The emulsifier used can, firstly, promote the formation of chitosan-ionic liquid-zein cross-linked structure among ionic liquid, chitosan and zein; secondly, promote the formation of grooves and pores on the surface and inside of chitosan-ionic liquid-zein microspheres, thereby increasing the surface area of ​​the microspheres; and thirdly, assist the molecular recognition core of plant essential oils to be better embedded in the chitosan-ionic liquid-zein cross-linked structure.

[0031] The chitosan-ionic liquid-zein microspheres of the present invention have high selectivity and absorption rate for specific plant essential oils, can be used to adsorb and concentrate specific plant essential oils in low-concentration environments, improve the utilization rate of plant essential oils, and have good application prospects in loading plant essential oils. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The microstructure of the chitosan-ionic liquid-zein microspheres in Example 4;

[0033] Figure 2 is another microstructure diagram of the chitosan-ionic liquid-zein microspheres in Example 4;

[0034] Figure 3 This is the Fourier infrared spectrum of the chitosan-ionic liquid-zein microspheres in Example 4;

[0035] Figure 4 This is the thermogravimetric analysis diagram of chitosan-ionic liquid-zein microspheres in Example 4;

[0036] Figure 5 The liquid chromatograms are of the plant essential oil in the condensate before and after being adsorbed by the chitosan-ionic liquid-zein microspheres in Example 4. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] Example 1

[0039] This embodiment provides a chitosan-ionic liquid-zein microsphere, wherein the surface of the chitosan-ionic liquid-zein microsphere has a groove structure.

[0040] A method for preparing the chitosan-ionic liquid-zein microspheres comprises the following steps:

[0041] (1) preparing 50 g of an acidic solvent, of which 41.6 g is acidic solvent A and 8.4 g is acidic solvent B;

[0042] (2) dissolving 1 g of zein powder and 0.02 g of chitosan powder in 41.6 g of acidic solvent A to obtain 42.62 g of translucent milky yellow mixed solution C;

[0043] (3) 1 g of Tween 20, 0.05 g of n-heptane and 1 g of ethyl acetate were dissolved in 8.4 g of acidic solvent B, and the mixture was stirred at a speed of 400 rpm for 10 minutes; then, 0.5 g of plant essential oil (lemon essential oil) and 0.1 g of ionic liquid (wherein 1-pentyl-3-methylimidazolium chloride was 0.05 g and 1-hexyl-3-methylimidazolium chloride was 0.05 g) were added simultaneously, and the mixture was stirred at a speed of 400 rpm for 5 minutes to obtain 11.05 g of milky white mixed solution D;

[0044] (4) 42.62 g of mixed solution C was poured into 11.05 g of mixed solution D at a rate of 15 ml / min, and stirred at a speed of 400 rpm for 30 min to obtain 53.67 g of a milky yellow mixed solution E;

[0045] (5) To 53.67 g of mixed solution E, 0.001 g of glutaraldehyde was added dropwise at a rate of 0.05 ml / min, and the mixture was stirred at 400 rpm for 150 min to obtain mixed solution F;

[0046] (6) The mixed solution F after the reaction was vacuum filtered, and the filter cake was rinsed with 200 ml of anhydrous ethanol and then dried in an oven at 70° C. for 36 hours to obtain 1.06 g of light yellow powder.

[0047] Example 2

[0048] This embodiment provides a chitosan-ionic liquid-zein microsphere, wherein the surface of the chitosan-ionic liquid-zein microsphere has a groove structure.

[0049] A method for preparing the chitosan-ionic liquid-zein microspheres comprises the following steps:

[0050] (1) preparing 50 g of an acidic solvent, of which 25 g is acidic solvent A and 25 g is acidic solvent B;

[0051] (2) dissolving 1 g of zein powder and 0.5 g of chitosan powder in 25 g of acidic solvent A to obtain 26.5 g of translucent milky yellow mixed solution C;

[0052] (3) 2 g of Tween 20, 1 g of n-heptane and 4 g of ethyl acetate were dissolved in 25 g of acidic solvent B, and the mixture was stirred at a speed of 400 rpm for 10 minutes; then, 1 g of plant essential oil (pine needle essential oil) and 0.7 g of ionic liquid (including 0.2 g of 1-pentyl-3-methylimidazolium chloride, 0.2 g of 1-hexyl-3-methylimidazolium chloride and 0.3 g of 1-octyl-3-methylimidazolium chloride) were added simultaneously, and the mixture was stirred at a speed of 400 rpm for 5 minutes to obtain 33.7 g of milky white mixed solution D;

[0053] (4) Pour 26.5 g of mixed solution C into 33.7 g of mixed solution D at a rate of 12 ml / min, and continue stirring at a speed of 400 rpm for 30 min to obtain 60.2 g of milky yellow mixed solution E;

[0054] (5) To 60.2 g of mixed solution E, 0.14 g of glutaraldehyde was added dropwise at a rate of 0.5 ml / min, and the mixture was stirred at a speed of 400 rpm for 150 min to obtain mixed solution F;

[0055] (6) The mixed solution F after the reaction was vacuum filtered, and the filter cake was rinsed with 200 ml of anhydrous ethanol and then placed in an oven at 70° C. to dry for 36 hours to obtain 1.9 g of light yellow powder.

[0056] Example 3

[0057] This embodiment provides a chitosan-ionic liquid-zein microsphere, wherein the surface of the chitosan-ionic liquid-zein microsphere has a groove structure.

[0058] A method for preparing the chitosan-ionic liquid-zein microspheres comprises the following steps:

[0059] (1) preparing 50 g of an acidic solvent, of which 8.4 g is acidic solvent A and 41.6 g is acidic solvent B;

[0060] (2) dissolving 1 g of zein powder and 1 g of chitosan powder in 8.4 g of acidic solvent A to obtain 10.4 g of translucent milky yellow mixed solution C;

[0061] (3) 3 g of Tween 20, 2.4 g of n-heptane and 9 g of ethyl acetate were dissolved in 41.6 g of acidic solvent B, and the mixture was stirred at a speed of 400 rpm for 10 minutes; then, 1.5 g of plant essential oil (including 1 g of lemon essential oil and 0.5 g of pine needle essential oil) and 1.5 g of ionic liquid (including 0.2 g of 1-hexyl-3-methylimidazole chloride, 0.7 g of 1-heptyl-3-methylimidazole chloride and 0.6 g of 1-octyl-3-methylimidazole chloride) were added simultaneously, and the mixture was stirred at a speed of 400 rpm for 5 minutes to obtain 59 g of milky white mixed solution D;

[0062] (4) Pour 10.4 g of mixed solution C into 59 g of mixed solution D at a rate of 15 ml / min, and continue stirring at a speed of 400 rpm for 30 min to obtain 69.4 g of milky yellow mixed solution E;

[0063] (5) To 69.4 g of mixed solution E, 0.45 g of glutaraldehyde was added dropwise at a rate of 1 ml / min, and the mixture was stirred at 400 rpm for 150 min to obtain mixed solution F;

[0064] (6) The mixed solution F after the reaction was vacuum filtered, and the filter cake was rinsed with 200 ml of anhydrous ethanol and then placed in an oven at 70° C. to dry for 36 hours to obtain 1.7 g of light yellow powder.

[0065] Example 4

[0066] This embodiment provides a chitosan-ionic liquid-zein microsphere, wherein the surface of the chitosan-ionic liquid-zein microsphere has a groove structure.

[0067] A method for preparing the chitosan-ionic liquid-zein microspheres comprises the following steps:

[0068] (1) preparing 50 g of an acidic solvent, of which 40 g is acidic solvent A and 10 g is acidic solvent B;

[0069] (2) dissolving 1 g of zein powder and 1 g of chitosan powder in 40 g of acidic solvent A to obtain 42 g of translucent milky yellow mixed solution C;

[0070] (3) 3 g of Tween 20, 1.5 g of n-heptane and 5 g of ethyl acetate were dissolved in 10 g of acidic solvent B, and the mixture was stirred at a speed of 400 rpm for 10 minutes; then, 1 g of plant essential oil (including 0.5 g of lemon essential oil and 0.5 g of pine needle essential oil) and 1 g of ionic liquid (including 0.4 g of 1-heptyl-3-methylimidazolium chloride and 0.6 g of 1-octyl-3-methylimidazolium chloride) were added simultaneously, and the mixture was stirred at a speed of 400 rpm for 5 minutes to obtain 21.5 g of milky white mixed solution D;

[0071] (4) Pour 42 g of mixed solution C into 21.5 g of mixed solution D at a rate of 10 ml / min, and continue stirring at a speed of 400 rpm for 30 min to obtain 63.5 g of milky yellow mixed solution E;

[0072] (5) To 63.5 g of mixed solution E, 0.1 g of glutaraldehyde was added dropwise at a rate of 1 ml per minute, and the mixture was stirred at a speed of 400 rpm for 150 min to obtain mixed solution F;

[0073] (6) The mixed solution F after the reaction was vacuum filtered, and the filter cake was rinsed with 200 ml of anhydrous ethanol and then placed in an oven at 70° C. to dry for 36 hours to obtain 2.8 g of light yellow powder.

[0074] The performance of the chitosan-ionic liquid-zein microspheres prepared in Example 4 was measured:

[0075] 1. Scanning electron microscopy

[0076] The scanning electron microscope was used for measurement with MIRA3 (Tesken, Czech Republic). Figure 1 and Figure 2 The morphology of chitosan-ionic liquid-zein microspheres at different magnifications is shown. Figure 1 Shown is the overall morphology of the microspheres, which have a particle size of 400 μm; Figure 2 The microsphere surface has a regular groove structure, which proves that it has a large surface area.

[0077] 2. Fourier transform infrared spectroscopy

[0078] The instrument used for Fourier transform infrared spectroscopy was Nicolet 6700 (Thermo Fisher Scientific, USA). Figure 3 In 943cm -1 、1080cm -1 、1640cm -1 CC, CO, and C=C vibration peaks appeared at 3180cm -1 and 2890cm -1 There are CN and NH vibration peaks at 1400cm -1 、1540cm -1 The CO vibration peak appeared at 2100 cm -1 and 3180cm -1 C=O and OH vibration peaks appeared at , which belonged to chitosan. Therefore, it was shown that chitosan-ionic liquid-zein microspheres were successfully prepared.

[0079] 3. Thermogravimetric analysis

[0080] Thermogravimetric analysis was performed using Labsys evo (Setaram, France). Figure 4 The results showed that chitosan-ionic liquid-zein microspheres lost 5.7% of their mass within 120°C due to the loss of water on the surface and in the voids; 35.1% of their mass between 200-350°C due to the decomposition of zein; and 40.1% of their mass between 400-700°C due to the decomposition of ionic liquid and chitosan. Therefore, the chitosan-ionic liquid-zein microspheres were successfully prepared.

[0081] Figure 5 The liquid chromatograms of the plant essential oil in the condensate before and after adsorption by the chitosan-ionic liquid-zein microspheres in Example 4, in which A is the liquid chromatogram before adsorption and B is the liquid chromatogram after adsorption. By comparing A and B, the peak area and peak height of B are significantly smaller than those of A, indicating that the concentration of the plant essential oil in the condensate is greatly reduced after adsorption, and also indicating that the chitosan-ionic liquid-zein microspheres have good adsorption performance for the plant essential oil in the condensate.

[0082] Comparative Example 1

[0083] This comparative example is based on Example 1, except that in this comparative example, the step "adding 0.5 g of plant essential oil and 0.1 g of ionic liquid simultaneously" in step (3) is replaced by "adding only 0.1 g of ionic liquid".

[0084] Comparative Example 2

[0085] This comparative example is based on Example 2, except that in this comparative example, the step of "adding 1 gram of plant essential oil and 0.7 gram of ionic liquid at the same time" in step (3) is replaced by "adding only 1 gram of plant essential oil".

[0086] Comparative Example 3

[0087] This comparative example is based on Example 3, except that in this comparative example, the step (4) of "pouring 10.4 g of mixed solution C into 59 g of mixed solution D at a rate of 15 ml per minute" is replaced by "rapidly mixing 10.4 g of mixed solution C with 59 g of mixed solution D".

[0088] The chitosan-ionic liquid-zein microspheres prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were used to measure the amount of plant essential oil adsorbed.

[0089] 50 ml of the water phase condensate after steam distillation of lemon peel, pine needles, pool cypress leaves, tea tree leaves, and lavender flowers were placed in a conical flask, and 1 gram of chitosan-ionic liquid-zein microspheres prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were added; the conical flask was shaken for 1 minute and then allowed to stand for 20 minutes, and the supernatant was taken. Subsequently, the essential oil content in the condensate before and after adsorption was determined by liquid chromatography.

[0090] Liquid chromatography conditions were as follows: LC3000 (CXTH, China), TC-C18 column (4.6×150 mm, 5 μm, Agilent, USA), mobile phase methanol / water (85:15, v / v), flow rate 0.8 mL / min, UV detector wavelength 470 nm, column temperature 30°C. The concentration of essential oil in the solution was calculated by the sum of peak areas.

[0091] The adsorption amount of plant essential oil is calculated by formula (1):

[0092]

[0093] Where qe is the adsorption amount of plant essential oil when adsorption reaches equilibrium, mg / g

[0094] C0 is the solution concentration before adsorption, mg / mL

[0095] Ce is the solution concentration at adsorption equilibrium, mg / mL

[0096] V is the volume of the solution, mL

[0097] m is the mass of the adsorbent material, g

[0098] The test results of the adsorption of plant essential oils are shown in Table 1;

[0099] Table 1 Plant essential oil adsorption amount of microspheres

[0100]

[0101]

[0102] The chitosan-ionic liquid-zein microspheres prepared in Example 1 use lemon essential oil as the molecular recognition core, and have the largest adsorption capacity for lemon essential oil. The chitosan-ionic liquid-zein microspheres prepared in Example 2 use pine needle essential oil as the molecular recognition core, and have the largest adsorption capacity for pine needle essential oil. The chitosan-ionic liquid-zein microspheres prepared in Example 3 and Example 4 use lemon essential oil and pine needle essential oil as the molecular recognition core, and therefore have a large adsorption capacity for both lemon essential oil and pine needle essential oil.

[0103] Like lemon essential oil and pine needle essential oil, pond cypress essential oil belongs to terpene essential oil and also contains a large amount of terpene molecules. Therefore, the chitosan-ionic liquid-zein microspheres prepared in Examples 1 to 4 have a certain selective adsorption for pond cypress essential oil.

[0104] Lemon essential oil, pine needle essential oil and pool cypress essential oil all contain a large amount of terpenoid molecules, while tea tree essential oil and lavender essential oil are mainly esters and alcohols. The adsorption amount of tea tree essential oil and lavender essential oil in Examples 1 to 4 is much smaller than that of lemon essential oil, pine needle essential oil and pool cypress essential oil, indicating that the chitosan-ionic liquid-zein microspheres prepared in Examples 1 to 4 have good selectivity, and the overall essential oil adsorption amount is also higher than that of Comparative Examples 1-3.

[0105] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A chitosan-ionic liquid-zein microsphere, characterized in that: The surface of the chitosan-ionic liquid-zein microspheres has a groove structure, and the raw materials thereof include the following components by weight: Acidic solvent: 50 parts Zein / chitosan mixture: 1.02-2 parts Emulsifier: 2.05 parts - 9.5 parts Plant essential oil: 0.5-1.5 parts Ionic liquid: 0.1-1.5 parts Glutaraldehyde: 0.001 parts to 0.45 parts.

2. The chitosan-ionic liquid-zein microspheres according to claim 1, characterized in that: The mass ratio of zein powder to chitosan powder in the zein / chitosan mixture is 1:(0.02-1).

3. The chitosan-ionic liquid-zein microspheres according to claim 1, characterized in that: The emulsifier is prepared by mixing Tween 20, n-heptane and ethyl acetate in a mass ratio of 1:(0.05-0.8):(1-3).

4. The chitosan-ionic liquid-zein microspheres according to claim 1, characterized in that: The plant essential oil is one or both of lemon essential oil and pine needle essential oil.

5. The chitosan-ionic liquid-zein microspheres according to claim 1, characterized in that: The ionic liquid is one or more of 1-pentyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-heptyl-3-methylimidazolium chloride and 1-octyl-3-methylimidazolium chloride.

6. The chitosan-ionic liquid-zein microspheres according to claim 5, characterized in that: The ionic liquid is a mixture of 1-pentyl-3-methylimidazolium chloride and 1-hexyl-3-methylimidazolium chloride.

7. A method for preparing chitosan-ionic liquid-zein microspheres according to any one of claims 1 to 6, characterized in that: The steps include: S1, adding glacial acetic acid to an ethanol aqueous solution to obtain an acidic solvent, and separating the acidic solvent into an acidic solvent A and an acidic solvent B; S2, dissolving zein powder and chitosan powder in the acidic solvent A to obtain a mixed solution C; S3, dissolving the emulsifier in the acidic solvent B, adding the plant essential oil and the ionic liquid after stirring evenly, and continuing to stir to obtain a mixed solution D; S4, dropping the mixed solution C into the mixed solution D, and continuously stirring at 400 rpm for 30 min to obtain a mixed solution E; S5, dropping glutaraldehyde into the mixed solution E at a rate of 0.05-1 mL / min, and continuously stirring at a speed of 400 rpm for 150 min to obtain a mixed solution F; S6. The mixed solution F is vacuum filtered, and the obtained filter cake is washed with ethanol and dried to obtain a light yellow powder, namely chitosan-ionic liquid-zein microspheres.

8. The preparation method according to claim 7, characterized in that: S1 is specifically: V1 mL of 75% ethanol aqueous solution is mixed with V2 mL of glacial acetic acid to obtain an acidic solvent, V2 = V1*2%, and the acidic solvent is divided into an acidic solvent A and an acidic solvent B.

9. The preparation method according to claim 8, characterized in that: The mass ratio of the acidic solvent A to the acidic solvent B in S1 is 0.2-5:

1.

10. Use of the chitosan-ionic liquid-zein microspheres according to any one of claims 1 to 6 in the selective adsorption of terpene essential oils.

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