Method for Extracting Anacardic Acid from Cashew Nut Shell

Abstract

The present invention relates to the field of plant extraction, and discloses a method for extracting anacardic acid from cashew nutshells. The method comprises the following steps: (1) crushing the cashew nutshells and then performing a separation treatment to obtain cashew nutshell oil; (2) mixing and reacting the cashew nutshell oil, solvent I and a settling agent, performing settling I and separation; the settling agent is phosphoric acid and / or phosphate. This method can effectively improve the yield and purity of anacardic acid extracted from cashew nutshells.

Description

Technical Field

[0001] The present invention relates to the field of plant extraction, and particularly to a method for extracting anacardic acid from cashew nutshells. Background Art

[0002] Cashew nutshells are by-products of the cashew industry. The main components of cashew nut shell liquid (CNSL) extracted from cashew nutshells through pressing or extraction processes are anacardic acid, cardol, cashew nut shell oil resin, etc. As a widely sourced renewable resource, the composition of cashew nut shell liquid mainly depends on the refining method. Cashew nut shell liquid contains about 90% anacardic acid and about 10% active substances such as cardol.

[0003] Anacardic acid will be used as a single product in emerging market fields such as lubricant additives, feed additives, epoxy resins, and the pharmaceutical field, and has various biological activities such as anti-tumor, snail-killing, inhibition of glucosidase and aldose reductase, and coupling effect on liver mitochondria. However, when using the distillation separation method, due to the high temperature, most of the anacardic acid decarboxylates and turns into cardanol. Therefore, the distillation separation method cannot separate anacardic acid, but can only separate cardanol from other substances.

[0004] Therefore, how to efficiently and conveniently separate anacardic acid from cashew nut shell liquid without destroying the structure and properties of each compound is an urgent problem to be solved. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems existing in the prior art and provide a method for extracting anacardic acid from cashew nutshells, which can effectively improve the yield and purity of anacardic acid extracted from cashew nutshells.

[0006] To achieve the above purpose, the present invention provides a method, including the following steps:

[0007] (1) Crushing cashew nutshells and then performing separation treatment to obtain cashew nut shell oil;

[0008] (2) Mixing and reacting the cashew nut shell oil, solvent I, and a settling agent, followed by settling I and separation;

[0009] The settling agent is phosphoric acid and / or phosphate.

[0010] Preferably, the phosphate is selected from at least one of potassium phosphate, sodium phosphate, magnesium phosphate, and calcium phosphate.

[0011] Preferably, the solvent I is selected from at least one of heptane, octane, nonane, and decane.

[0012] Preferably, in step (2), the weight ratio of the cashew shell oil, the solvent I and the precipitant is 1: 0.1-0.2: 0.06-0.1.

[0013] Preferably, the conditions of the mixed reaction include at least: the temperature is 60-70 °C and the time is 1-2 h.

[0014] Preferably, in step (2), the process of the first sedimentation includes: adding a solvent II to the product of the mixed reaction.

[0015] Preferably, the solvent II is selected from at least one of heptane, octane, nonane and decane.

[0016] Preferably, the weight ratio of the solvent II to the cashew shell oil is 0.4-0.6: 1.

[0017] Preferably, in step (1), the particle size of the crushed cashew shell is 1 / 4-1 / 3 of the particle size of the cashew shell before crushing.

[0018] Preferably, in step (1), the process of the separation treatment includes: pressing and second sedimentation of the crushed cashew shell.

[0019] Preferably, the process of the second sedimentation includes: mixing the cashew shell liquid obtained by pressing with a phosphoric acid-aqueous solution and then performing a sedimentation treatment.

[0020] Preferably, the concentration of phosphoric acid in the phosphoric acid-aqueous solution is 2-10% by weight.

[0021] Preferably, the weight ratio of the phosphoric acid-aqueous solution to the cashew shell is 4×10 -4 -7×10 -4 : 1.

[0022] Preferably, the cashew shell liquid obtained by pressing, the phosphoric acid-aqueous solution and the water-absorbing resin are mixed and then a sedimentation treatment is performed.

[0023] Preferably, the concentration of phosphoric acid in the phosphoric acid-aqueous solution is 2-10% by weight, and the water-absorbing resin is a wood cellulose copolymer water-absorbing resin.

[0024] Preferably, the weight ratio of the phosphoric acid-aqueous solution to the cashew shell is 4×10 -4 -7×10 -4 : 1.

[0025] Preferably, before the separation treatment, the crushed cashew shell is soaked with a swelling agent.

[0026] Preferably, the swelling agent is an aqueous solution of sodium persulfate.

[0027] Preferably, the concentration of sodium persulfate in the sodium persulfate - aqueous solution is 4 - 6% by weight.

[0028] Preferably, the method further includes: in step (2), concentrating the separated product to obtain the anacardic acid.

[0029] Preferably, the conditions for concentration include: the pressure is -0.9 MPa to -0.1 MPa, the temperature is 30 - 70 °C, the rotation speed is 60 - 80 rpm, and the time is 60 - 90 min.

[0030] By the above technical solution, the beneficial effects of the present invention are as follows:

[0031] The method for extracting anacardic acid from cashew nutshells provided by the present invention adds solvent I and a precipitant to cashew nutshell oil, and the precipitant is phosphoric acid and / or phosphate. This method can effectively improve the yield and purity of anacardic acid extracted from cashew nutshells; the precipitant can polymerize with phospholipids in cashew nutshell oil, making it easier to sediment; solvent I can dilute cashew nutshell oil, reduce the viscosity index of cashew nutshell oil, and make the polymer micro - particles of cashew nutshell oil resin convenient for solid - liquid separation, thereby improving the purity of anacardic acid extracted from cashew nutshells.

[0032] The method for extracting anacardic acid from cashew nutshells provided by the present invention can open the network structure in cashew nutshells by soaking the crushed cashew nutshells in a swelling agent, thereby increasing the yield of cashew nutshell oil; by mixing the cashew nutshell liquid obtained by pressing with a phosphoric acid - aqueous solution for sedimentation, the yield and purity of anacardic acid extracted from cashew nutshells are further improved. Description of the Drawings

[0033] Figure 1 is the process flow of extracting anacardic acid from cashew nutshells in Example 1. Detailed Embodiments

[0034] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0035] The present invention provides a method for extracting anacardic acid from cashew nutshells, including the following steps:

[0036] (1) Crushing the cashew nutshells and then performing a separation treatment to obtain cashew nutshell oil;

[0037] (2) Mixing, reacting, sedimenting I, and separating the cashew nutshell oil, solvent I, and precipitant.

[0038] The sedimentation agent is phosphoric acid and / or phosphate.

[0039] During the research process, the inventors of the present invention found that when phosphoric acid and / or phosphate is used as the sedimentation agent, its reaction with anacardic acid is not strong, the damage to anacardic acid is small, and it has a good effect on degreasing and decoloring vegetable oils. At the same time, phosphoric acid and / or phosphate has a relatively large specific gravity and is easy to sediment after polymerization with phospholipids in cashew shell oil. By mixing and reacting cashew shell oil, solvent I and the sedimentation agent, followed by sedimentation I and separation, anacardic acid can be obtained, effectively improving the yield and purity of anacardic acid extracted from cashew shells.

[0040] According to the present invention, in order to further improve the yield of anacardic acid extracted from cashew shells, preferably, the phosphate is selected from at least one of potassium phosphate, sodium phosphate, magnesium phosphate and calcium phosphate.

[0041] According to the present invention, preferably, the solvent I is selected from at least one of heptane, octane, nonane and decane. The inventors found that under this preferred specific embodiment, the solvent I can dilute the cashew shell oil, reduce the viscosity index of the cashew shell oil, facilitate the solid-liquid separation of the resin microparticle polymer in the cashew shell oil, and thus improve the yield and purity of anacardic acid extracted from cashew shells.

[0042] According to the present invention, in order to further improve the yield and purity of anacardic acid extracted from cashew shells, preferably, in step (2), the weight ratio of the cashew shell oil, the solvent I to the sedimentation agent is 1:0.1 - 0.2:0.04 - 0.1.

[0043] According to the present invention, preferably, the conditions for the mixing reaction include at least: the temperature is 60 - 70°C, specifically it can be 60°C, 65°C, 70°C, or any value between the aforementioned two values; the time is 1 - 2 h, specifically it can be 1 h, 1.5 h, 2 h, or any value between the aforementioned two values.

[0044] According to the present invention, preferably, in step (2), the process of sedimentation I includes: adding solvent II to the product of the mixing reaction. The inventors found that under this preferred specific embodiment, the solvent II can further dilute the cashew shell oil, reduce the viscosity index of the cashew shell oil, promote the solid-liquid separation of the resin microparticle polymer in the cashew shell oil, and thus further improve the yield and purity of anacardic acid extracted from cashew shells.

[0045] According to the present invention, in order to further improve the yield and purity of anacardic acid extracted from cashew shells, preferably, the solvent II is selected from at least one of heptane, octane, nonane and decane.

[0046] According to the present invention, in order to further improve the yield of cardanol extracted from cashew nut shells, preferably, the weight ratio of the solvent II to the cashew nut shell oil is 0.4 - 0.6:1, specifically, it can be 0.4:1, 0.5:1, 0.6:1, or any value between the aforementioned two values.

[0047] According to the present invention, preferably, in step (1), the particle size of the crushed cashew nut shells is 1 / 4 - 1 / 3 of the particle size of the cashew nut shells before crushing. The inventors found that under this preferred specific embodiment, by crushing to break the fibers of the cashew nut shells, the cross-sectional area of the cashew nut shells can be increased, thereby improving the oil yield of the cashew nut shells.

[0048] In the present invention, there is no particular limitation on the crushing method, and conventional crushing methods in the art can be adopted.

[0049] In the present invention, before crushing the cashew nut shells, it is also necessary to screen and remove stones from the purchased cashew nut shells to improve the crushing efficiency and protect the device for crushing the cashew nut shells.

[0050] According to the present invention, preferably, in step (1), the separation process includes: pressing and sedimentation II of the crushed cashew nut shells. The inventors found that under this preferred specific embodiment, the content of cardanol in the extracted cashew nut shell oil can be improved.

[0051] According to the present invention, in order to further improve the content of cardanol in the extracted cashew nut shell oil, preferably, the sedimentation II process includes: mixing the cashew nut shell liquid obtained by pressing with a phosphoric acid - aqueous solution and then performing sedimentation treatment.

[0052] According to the present invention, in order to further improve the content of cardanol in the extracted cashew nut shell oil, preferably, the concentration of phosphoric acid in the phosphoric acid - aqueous solution is 2 - 10 wt%, specifically, it can be 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, or any value between the aforementioned two values.

[0053] Preferably, the weight ratio of the phosphoric acid - aqueous solution to the cashew nut shells is 4×10 -4 -7×10 -4 :1, specifically, it can be 4×10 -4 :1, 5×10 -4 :1, 6×10 -4 :1, 7×10 -4 :1, or any value between the aforementioned two values.

[0054] In the present invention, before mixing the pressed cashew nut shell liquid with the phosphoric acid - aqueous solution, the cashew nut shell liquid can be filtered. Exemplarily, the cashew nut shell liquid can be filtered through a 120 - mesh metal filter screen, which can increase the content of anacardic acid in the cashew nut shell oil obtained in the second sedimentation process.

[0055] In the present invention, before pressing the crushed cashew nut shells, the cashew nut shells can be first put into a filter cloth bag, which can wrap the cashew nut shell oil resin and residue in the filter cloth bag when pressing the cashew nut shells, making it easy to obtain the cashew nut shell liquid; there is no special limitation on the pore size of the filter cloth bag. Preferably, the pore size is not less than 100 mesh, which can effectively intercept the cashew nut oil resin and impurities in the cashew nut shell liquid, thereby increasing the content of the active ingredients in the cashew nut shell liquid.

[0056] In the present invention, there is no special limitation on the pressing method, and conventional pressing methods in the art can be adopted. For example, a 60 Mpa - 40X80 (300 - ton thrust) hydraulic oil press can be used for pressing.

[0057] According to the present invention, preferably, the process of the second sedimentation includes: mixing the pressed cashew nut shell liquid, the phosphoric acid - aqueous solution and the water - absorbing resin, and then performing sedimentation treatment. The inventors have found that under this preferred specific embodiment, the water - absorbing resin can absorb the water in the cashew nut shell liquid, promote the separation of the active ingredients in the cashew nut shell liquid, improve the sedimentation effect, increase the content of anacardic acid in the extracted cashew nut shell oil, and thus further increase the yield and purity of anacardic acid extracted from cashew nut shells.

[0058] According to the present invention, in order to further increase the yield and purity of anacardic acid extracted from cashew nut shells, preferably, the concentration of phosphoric acid in the phosphoric acid - aqueous solution is 2 - 10 wt%, specifically it can be 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, or any value between the aforementioned two values; the water - absorbing resin is a wood cellulose copolymer water - absorbing resin.

[0059] In the present invention, there is no special limitation on the dosage of the water - absorbing resin, and those skilled in the art can select according to specific circumstances.

[0060] Preferably, the weight ratio of the phosphoric acid - aqueous solution to the cashew nut shells is 4×10 -4 - 7×10 -4 :1, specifically it can be 4×10 -4 :1, 5×10 -4 :1, 6×10 -4 :1, 7×10 -4 :1, or any value between the aforementioned two values.

[0061] The above - mentioned substances can all be obtained through commercial purchase.

[0062] According to the present invention, preferably, before the separation treatment, the crushed cashew nutshells are soaked with a swelling agent. The inventors have found that under this preferred specific embodiment, the swelling agent can soften the cashew nutshells and can open the reticular fiber structure of the cashew nutshells, making the cashew nutshells easy to press, thereby increasing the yield of cashew nutshell oil extracted from the cashew nutshells.

[0063] According to the present invention, in order to further increase the yield of cashew nutshell oil extracted from the cashew nutshells, preferably, the swelling agent is an aqueous solution of sodium persulfate.

[0064] According to the present invention, in order to further increase the yield of cashew nutshell oil extracted from the cashew nutshells, preferably, the concentration of sodium persulfate in the aqueous solution of sodium persulfate is 4-6% by weight, specifically it can be 4% by weight, 5% by weight, 6% by weight, or any value between the aforementioned two values.

[0065] In the present invention, there is no particular limitation on the dosage of the swelling agent, as long as the cashew nutshells can be immersed in the swelling agent. Preferably, the weight ratio of the swelling agent to the cashew nutshells is 1-3:1, specifically it can be 1:1, 2:1, 3:1, or any value between the aforementioned two values.

[0066] In the present invention, there is no particular limitation on the conditions for soaking the crushed cashew nutshells with the swelling agent. In order to further increase the yield of cashew nutshell oil in the cashew nutshells, preferably, the soaking conditions include: the temperature is 30-50 °C, specifically it can be 30 °C, 40 °C, 50 °C, or any value between the aforementioned two values; the time is 10-12 h, specifically it can be 10 h, 11 h, 12 h, or any value between the aforementioned two values.

[0067] In the present invention, after the crushed cashew nutshells are soaked with the swelling agent, the swelling agent can be recovered or reused to improve the utilization rate of the swelling agent, playing a role in energy conservation and environmental protection.

[0068] According to the present invention, in order to further increase the yield of cashew nutshell oil extracted from the cashew nutshells, preferably, the method further includes: in step (2), concentrating the separated product to obtain the cardanol.

[0069] According to the present invention, preferably, the concentration conditions include: a pressure of -0.9 MPa to -0.1 MPa, specifically, it can be -0.9 MPa, -0.7 MPa, -0.5 MPa, -0.3 MPa, -0.1 MPa, or any value between the aforementioned two values; a temperature of 30 - 70 °C, specifically, it can be 30 °C, 50 °C, 70 °C, or any value between the aforementioned two values; a rotation speed of 60 - 80 rpm, specifically, it can be 60 rpm, 70 rpm, 80 rpm, or any value between the aforementioned two values; a time of 60 - 90 min, specifically, it can be 60 min, 70 min, 80 min, 90 min, or any value between the aforementioned two values.

[0070] In the present invention, the separation method in step (2) can be a conventional separation method in the art, such as centrifugation, and the rotation speed of centrifugation is preferably 7000 - 8000 rpm. The inventors found that in this preferred specific embodiment, the cashew shell oil suspended in the form of a polymer in the anacardic acid can be separated out.

[0071] According to a particularly preferred embodiment of the present invention, a method for extracting anacardic acid from cashew shells is provided, including the following steps:

[0072] (1) After crushing the cashew shells, soak them in an aqueous solution of sodium persulfate at a temperature of 30 - 50 °C for 10 - 12 h, and then put the crushed cashew shells into a filter cloth bag for pressing to obtain a cashew shell liquid; mix the cashew shell liquid with an aqueous solution of phosphoric acid and add a lignocellulose copolymer water-absorbing resin for sedimentation II to obtain cashew shell oil;

[0073] (2) Mix and react the cashew shell oil, solvent I, and a precipitant at a temperature of 60 - 70 °C and a rotation speed of 60 - 80 rpm for 1 - 2 h, and add solvent II to the product of the mixing reaction for sedimentation I and separation;

[0074] (3) Concentrate the product separated in step (2) under the conditions of a pressure of -0.9 Mpa to -0.1 Mpa, a temperature of 30 - 70 °C, and a rotation speed of 60 - 80 rpm for 60 - 90 min to obtain anacardic acid;

[0075] In step (1), the particle size of the crushed cashew shells is 1 / 4 - 1 / 3 of the particle size of the cashew shells before crushing; the concentration of phosphoric acid in the aqueous solution of phosphoric acid is 2 - 10 wt%, and the weight ratio of the aqueous solution of phosphoric acid to the cashew shells is 4×10 -4 -7×10 -4 :1; the concentration of sodium persulfate in the aqueous solution of sodium persulfate is 4 - 6 wt%;

[0076] In step (2), the phosphate is selected from at least one of potassium phosphate, sodium phosphate, magnesium phosphate and calcium phosphate; the solvent I is selected from at least one of heptane, octane, nonane and decane; the weight ratio of cashew shell oil, solvent I to the settling agent is 1:0.1 - 0.2:0.04 - 0.1; the solvent II is selected from at least one of heptane, octane, nonane and decane; the weight ratio of solvent II to cashew shell oil is 0.4 - 0.6:1.

[0077] In the above particularly preferred embodiments, the yield and purity of cardanol extracted from cashew shells can be effectively improved.

[0078] The present invention will be described in detail below in conjunction with embodiments, but the scope of the present invention is not limited thereby.

[0079] The present invention will be described in detail below through embodiments. The cashew shells were purchased from Fuyong (Shandong) Biotechnology Co., Ltd.; the lignocellulose copolymer water-absorbing resin was purchased from Henan Hairui Chemical Products Co., Ltd., with the model being a superabsorbent resin; phosphoric acid (industrial grade) was purchased from Shandong Zhenhua Industry Co., Ltd. There are no special restrictions on other raw materials, and they are all commercially available products.

[0080] Example 1

[0081] (1) 100 kg of cashew shells were crushed to a particle size of 1 / 3 - 1 / 4 of the original shell size, and then poured into 150 kg of an expanding agent (an aqueous solution of sodium persulfate with a concentration of 5% by weight of sodium persulfate) and soaked at 40 °C for 12 h. After draining the expanding agent, the cashew shells were put into a feed bin and packed into 100-mesh filter bags of 50 kg / bag. The filter bags were layered and placed in a 60 Mpa - 40X80 (300-ton thrust) hydraulic oil press to extract 9480 g of cashew shell liquid. After preliminary filtration through a 120-mesh metal filter, it flowed into a constant-temperature 40 °C settling tank and was added with 50 g of an aqueous solution of phosphoric acid with a concentration of 5% by weight of phosphoric acid and 40 g of lignocellulose copolymer water-absorbing resin for natural sedimentation to obtain 3555 g of cashew shell oil;

[0082] (2) 2000 g of cashew shell oil was weighed, 300 g of heptane was added and stirred evenly, then 160 g of phosphoric acid was added and stirred evenly, and the temperature was gradually raised to 65 °C for a mixing reaction for 1.5 h; 1000 g of heptane was added to the product of the mixing reaction, and it was poured out and settled at 50 °C for 24 h, and then a large amount of cashew shell oil resin and residues were separated; after the sedimentation layering was completed, the upper layer solution was separated at a rotation speed of 7000 rpm;

[0083] (3) The material separated in step (2) was subjected to vacuum distillation at a pressure of -0.6 MPa and a rotation speed of 70 rpm for 80 min to obtain 1920 g of cardanol with an acid value of 120 KOH / g, and the color became lighter compared to cashew shell oil.

[0084] Example 2

[0085] (1) Crush 100 kg of cashew nutshells to a particle size of 1 / 3 - 1 / 4 of the original shell, then pour into 150 kg of an expander (an aqueous solution of sodium persulfate with a concentration of 4% by weight of sodium persulfate), soak for 10 h at 50 °C, drain the expander, and then put the cashew nutshells into the feed bin and pack them into 100-mesh filter bags of 50 kg / bag. Stack the filter bags layer by layer and place them in a 60 Mpa - 40X80 (300-ton thrust) hydraulic oil press to extract 9261 g of cashew nutshell liquid. After preliminary filtration through a 120-mesh metal filter screen, it flows into a sedimentation tank at a constant temperature of 40 °C, add 40 g of phosphoric acid (an aqueous solution of phosphoric acid with a concentration of 10% by weight) and 30 g of lignocellulose copolymer water-absorbing resin, and let it settle naturally to obtain 3463 g of cashew nutshell oil;

[0086] (2) Weigh 2000 g of cashew nutshell oil, add 200 g of heptane and stir evenly, then add 120 g of phosphoric acid and stir evenly, and gradually heat up to 70 °C for a mixing reaction for 1 h; add 800 g of heptane to the product of the mixing reaction, pour it out and let it settle for 24 h at 50 °C, then separate a large amount of cashew nutshell oil resin and residues; after the sedimentation and stratification are completed, take the upper layer solution and separate it at a rotational speed of 7000 rpm;

[0087] (3) Carry out vacuum distillation on the material separated in step (2) at a pressure of -0.9 MPa and a rotational speed of 60 rpm for 60 min to obtain 1888 g of cashew nut acid with an acid value of 130 KOH / g, and the color becomes lighter compared to the cashew nutshell oil.

[0088] Example 3

[0089] (1) Crush 100 kg of cashew nutshells to a particle size of 1 / 3 - 1 / 4 of the original shell, then pour into 150 kg of an expander (an aqueous solution of sodium persulfate with a concentration of 6% by weight of sodium persulfate), soak for 12 h at 30 °C, drain the expander, and then put the cashew nutshells into the feed bin and pack them into 100-mesh filter bags of 50 kg / bag. Stack the filter bags layer by layer and place them in a 60 Mpa - 40X80 (300-ton thrust) hydraulic oil press to extract 9413 g of cashew nutshell liquid. After preliminary filtration through a 120-mesh metal filter screen, it flows into a sedimentation tank at a constant temperature of 40 °C, add 60 g of phosphoric acid (an aqueous solution of phosphoric acid with a concentration of 2% by weight) and 25 g of lignocellulose copolymer water-absorbing resin, and let it settle naturally to obtain 3451 g of cashew nutshell oil;

[0090] (2) Weigh 2000 g of cashew nut shell oil, add 400 g of heptane and stir evenly. Then add 200 g of phosphoric acid, stir evenly and gradually heat up to 60 °C for a mixing reaction for 2 h. Add 1200 g of heptane to the product of the mixing reaction, pour it out and let it settle at 50 °C for 24 h, then separate a large amount of cashew nut shell oil resin and residues. After the sedimentation and stratification are completed, take the upper layer solution and separate it at a rotation speed of 7000 rpm;

[0091] (3) Carry out vacuum distillation on the material separated in step (2) at a pressure of -0.1 MPa and a rotation speed of 80 rpm for 90 min to obtain 1882 g of cashew nut acid with an acid value of 110 KOH / g, and the color becomes lighter compared to the cashew nut shell oil.

[0092] Example 4

[0093] Extract cashew nut acid according to the method of Example 1, except that step (2) is replaced with:

[0094] (2) Weigh 2000 g of cashew nut shell oil, add 300 g of heptane and stir evenly. Then add 160 g of phosphoric acid, stir evenly and gradually heat up to 65 °C for a mixing reaction for 1.5 h, pour it out and let it settle at 50 °C for 24 h, then separate a large amount of cashew nut shell oil resin and residues. After the sedimentation and stratification are completed, take the upper layer solution and separate it at a rotation speed of 7000 rpm.

[0095] Example 5

[0096] Extract cashew nut acid according to the method of Example 1, except that the dosage of phosphoric acid in step (2) is replaced with 60 g.

[0097] Example 6

[0098] Extract cashew nut acid according to the method of Example 1, except that step (1) is replaced with:

[0099] (1) Crush 100 kg of cashew nut shells to a particle size of 1 / 3 - 1 / 4 of the original shell size. Put the cashew nut shells into the feed bin and pack them into 100-mesh filter bags of 50 kg / bag. Stack the filter bags layer by layer and place them in a 60 Mpa - 40X80 (300-ton thrust) hydraulic oil press to extract 9210 g of cashew nut shell liquid. After preliminary filtration through a 120-mesh metal filter net, it flows into a constant-temperature 40 °C sedimentation tank and adds 70 g of phosphoric acid - aqueous solution with a concentration of 5 wt% and 30 g of lignocellulose copolymer water-absorbing resin for natural sedimentation to obtain 3110 g of cashew nut shell oil.

[0100] Example 7

[0101] Extract anacardic acid according to the method of Example 1, except that in step (1), the lignocellulose copolymer water-absorbing resin is not added.

[0102] Example 8

[0103] Extract anacardic acid according to the method of Example 1, except that step (1) is replaced with:

[0104] (1) Crush 100 kg of cashew nutshells to a particle size of 1 / 3 - 1 / 4 of the original shell, then pour it into 150 kg of an expander (an aqueous solution of sodium persulfate with a concentration of 5% by weight of sodium persulfate), soak it at 40 °C for 12 h, drain the expander, and then put the cashew nutshells into the feed bin and pack them into 100-mesh filter bags of 50 kg / bag. Stack the filter bags layer by layer and put them into a 60 Mpa - 40X80 (300-ton thrust) hydraulic oil press to extract 9348 g of cashew nutshell liquid. After preliminary filtration through a 120-mesh metal filter screen, it flows into a sedimentation tank at a constant temperature of 40 °C for natural sedimentation to obtain 3048 g of cashew nutshell oil.

[0105] Comparative Example 1

[0106] Extract anacardic acid according to the method of Example 1, except that step (2) is replaced with:

[0107] (2) Weigh 2000 g of cashew nutshell oil, add 160 g of phosphoric acid, stir evenly, and gradually heat up to 65 °C for a mixing reaction of 1.5 h; pour it out and let it settle at 50 °C for 24 h, then separate the cashew nutshell oil resin and the residue; after the sedimentation and stratification are completed, take the upper layer solution and separate it at a rotation speed of 7000 rpm.

[0108] Comparative Example 2

[0109] Extract anacardic acid according to the method of Example 1, except that step (2) is replaced with:

[0110] (2) Weigh 2000 g of cashew nutshell oil, add 1300 g of heptane, stir evenly, then pour it out and let it settle at 50 °C for 24 h, then separate the cashew nutshell oil resin and the residue; after the sedimentation and stratification are completed, take the upper layer solution and separate it at a rotation speed of 7000 rpm.

[0111] Comparative Example 3

[0112] Extract anacardic acid according to the method of Example 1, except that in step (2), the sedimentation agent is replaced with acetic acid.

[0113] Test Example

[0114] The purity of cardanol extracted in Examples 1 - 8 and Comparative Examples 1 - 3 was tested using an LC - 20A high - performance liquid chromatograph, and the yield of cardanol was calculated. The yield of cardanol (%) = m 腰果酸 / m 腰果壳液 . The results of the yields and purities of cardanol in Examples 1 - 8 and Comparative Examples 1 - 3 are shown in Table 1.

[0115] Table 1

[0116]

[0117]

[0118] As can be seen from the results in Table 1, compared with Comparative Examples 1 - 3, the yields and purities of cardanol extracted from cashew nutshells by the method provided by the present invention in Examples 1 - 8 are both increased. The sedimentation agent polymerizes with the phospholipids in the cashew nutshell oil, making it easy to sediment; Solvent I dilutes the cashew nutshell oil, reducing the viscosity index of the cashew nutshell oil, making it convenient for the solid - liquid separation of the cashew nutshell oil resin microparticle polymer and improving the purity of cardanol extracted from the cashew nutshell; By soaking the crushed cashew nutshells in the swelling agent, the network structure in the cashew nutshells is opened, increasing the yield of cashew nutshell oil; By mixing the pressed cashew nutshell liquid with a phosphoric acid - aqueous solution for sedimentation, the yields and purities of cardanol extracted from the cashew nutshells are further improved.

[0119] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for extracting anacardic acid from cashew nut shells, characterized in that, It includes the following steps: (1) Crush the cashew nut shell and then carry out separation treatment to obtain cashew nut shell oil; (2) Mix and react the cashew nut shell oil, solvent I and sedimentation agent, followed by sedimentation I and separation; The sedimentation agent is phosphoric acid and / or phosphate; the solvent I is selected from at least one of heptane, octane, nonane and decane; the weight ratio of the cashew nut shell oil, the solvent I to the sedimentation agent is 1:0.1 - 0.2:0.04 - 0.1; the conditions of the mixing reaction include at least: temperature is 60 - 70 °C, time is 1 - 2 h.

2. The method according to claim 1, characterized in that, The phosphate is selected from at least one of potassium phosphate, sodium phosphate, magnesium phosphate and calcium phosphate.

3. The method according to claim 1, characterized in that, In step (2), the process of sedimentation I includes: adding solvent II to the product of the mixing reaction; The solvent II is selected from at least one of heptane, octane, nonane and decane.

4. The method according to claim 3, characterized in that, The weight ratio of the solvent II to the cashew nut shell oil is 0.4 - 0.6:

1.

5. The method according to any one of claims 1 to 4, characterized in that, In step (1), the particle size of the crushed cashew nut shell is 1 / 4 - 1 / 3 of the particle size of the cashew nut shell before crushing.

6. The method according to any one of claims 1 to 4, characterized in that, In step (1), the process of the separation treatment includes: pressing and sedimentation II of the crushed cashew nut shell.

7. The method according to claim 6, characterized in that, The process of sedimentation II includes: mixing the cashew nut shell liquid obtained by pressing with a phosphoric acid - aqueous solution and then carrying out sedimentation treatment.

8. The method according to claim 7, characterized in that, The concentration of phosphoric acid in the phosphoric acid - aqueous solution is 2 - 10% by weight.

9. The method according to claim 8, characterized in that, The weight ratio of the phosphoric acid-aqueous solution to the cashew shell is 4×10 -4 -7×10 -4 :

1.

10. The method according to claim 6, characterized in that, The process of sedimentation II includes: mixing the cashew nut shell liquid obtained by pressing, the phosphoric acid - aqueous solution and a water - absorbing resin and then carrying out sedimentation treatment.

11. The method according to claim 10, characterized in that, The concentration of phosphoric acid in the phosphoric acid - aqueous solution is 2 - 10% by weight, and the water - absorbing resin is a wood cellulose copolymer water - absorbing resin.

12. The method according to claim 11, characterized in that, The weight ratio of the phosphoric acid-aqueous solution to the cashew shell is 4×10 -4 -7×10 -4 :

1.

13. The method according to any one of claims 1 to 4, characterized in that, Before the separation treatment, soak the crushed cashew nut shell with an expanding agent.

14. The method according to claim 13, characterized in that, The expanding agent is a sodium persulfate - aqueous solution.

15. The method according to claim 14, characterized in that, The concentration of sodium persulfate in the sodium persulfate - aqueous solution is 4 - 6% by weight.

16. The method according to any one of claims 1 to 4, characterized in that, This method further includes: in step (2), concentrating the separated product to obtain the cardanol acid.

17. The method according to claim 16, characterized in that, The conditions of the concentration include: pressure is - 0.9 MPa to - 0.1 MPa, temperature is 30 - 70 °C, rotation speed is 60 - 80 rpm, and time is 60 - 90 min.

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