Method for removing heavy metal ions in acidified palm oil

Abstract

The invention discloses a method for removing heavy metal ions in acidified palm oil, which comprises the following steps: (1) sequentially adding a mixed treating agent and a eutectic solvent into preheated to-be-purified acidified palm oil, and reacting at high temperature; and (2) adding a settling aid into the mixed solution after the reaction in the step (1), fully precipitating, taking out the supernate, adding an adsorbent into the supernate, and filtering after the adsorption is completed, thereby obtaining the purified acidified palm oil. According to the method, the content of the heavy metal ions in the palm oil obtained through separation can be remarkably reduced, the removal rate of the metal ions can reach 90% or above, and the heavy metal ions in the acidified palm oil can be rapidly removed.

Description

Technical Field

[0001] The invention relates to a method for removing heavy metal ions in acidified palm oil. Background Art

[0002] Biodiesel is a liquid biofuel produced from vegetable oils (such as palm oil, moringa oil, jatropha oil), animal fats and microalgae. It is a renewable alternative to diesel. As a renewable energy source, the production of biofuels, especially biodiesel, has increased in the past decade.

[0003] As the first generation of biofuel, palm oil is the main raw material for the production of biodiesel. Compared with other edible oils and non-edible oils, palm oil has the greatest potential. Acidified palm oil is a by-product obtained after palm oil refining. Some heavy metal ions exist in acidified palm oil, and the highest content includes iron ions, calcium ions, sodium ions and aluminum ions. It is well known that trace amounts of Cu, Fe, Mn and Ni will greatly reduce the oxidative stability of fats and oils, while Ca, Mg and Na will reduce the efficiency of refining, degumming, bleaching and hydrogenation processes.

[0004] According to the detection data of metal impurities in acidified palm oil, iron is the main element that causes the metal impurities in palm oil to exceed the standard, followed by calcium and aluminum. The phenomenon of other metal elements exceeding the standard is not common. In the purification of biodiesel, when the heavy metal content in palm oil exceeds the limit specified in the standard, the heavy metals need to be removed to ensure the subsequent preparation and service life of biodiesel. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a method for removing heavy metal ions in acidified palm oil, which can achieve a metal ion removal rate of more than 90%.

[0006] Technical solution: The method for removing heavy metal ions from acidified palm oil of the present invention comprises the following steps:

[0007] (1) adding a mixed treatment agent and a eutectic solvent to the preheated acidified palm oil to be purified in sequence, and reacting at high temperature;

[0008] (2) adding a precipitation aid to the mixed solution after the reaction in step (1), taking out the supernatant after sufficient precipitation, adding an adsorbent thereto, and filtering to obtain purified acidified palm oil after adsorption.

[0009] Wherein, in step (1), the mixed treatment agent is prepared by the following method, specifically: disodium ethylenediaminetetraacetate (metal impurity removal agent), heptanoic acid (removal reaction promoter) and ethanol aqueous solution are mixed to obtain the mixed treatment agent.

[0010] The volume concentration of the ethanol aqueous solution is 75-80%.

[0011] The mixing mass ratio of disodium ethylenediaminetetraacetate, heptanoic acid and ethanol aqueous solution is 1-3:0.5-1.6:3-9.

[0012] The amount of disodium ethylenediaminetetraacetate added is 1-4% of the mass of the acidified palm oil to be purified; the amount of heptanoic acid added is 1-2% of the mass of the acidified palm oil to be purified; and the amount of ethanol aqueous solution added is 6-12% of the mass of the acidified palm oil to be purified.

[0013] Wherein, in step (1), the eutectic solvent is prepared by the following method, specifically: choline chloride, lactic acid (choline chloride and lactic acid can accelerate the sedimentation and precipitation of metal ions, so that they can quickly chelate with the chelating agent; the eutectic solvent is composed of a mixture of organic salts and hydrogen bond donor compounds, mainly adding a eutectic agent to the heated palm oil, through linear integrated precipitation, so that the heavy metals in the dissolved state can generate more precipitates to achieve a better removal effect) and water are mixed at a temperature not lower than 100°C to obtain a eutectic solvent (uniform liquid phase).

[0014] The mixing molar ratio of choline chloride, lactic acid and water is 1.0:1.0:5.5-6.

[0015] Wherein, in step (1), the preheating temperature of the acidified palm oil is 60-70°C; the reaction temperature is 60-70°C, and the reaction time is 20-40 min.

[0016] Wherein, in step (2), the sedimentation aid is silica gel particles (particle size is 20 μm); the mass ratio of the sedimentation aid to the acidified palm oil to be purified is 1-3:50-80; and the sedimentation aid time is 2-3 hours.

[0017] Wherein, in step (2), the adsorbent is 200-300 mesh activated white clay, the mass ratio of the adsorbent to the acidified palm oil to be purified is 1.5-4:50-80; and the adsorption time is 50-60 min.

[0018] Removal mechanism of heavy metal impurities in the form of metallic particles: The prepared mixed treatment agent is a synthetic amino acid. When disodium ethylenediaminetetraacetate combines with calcium ions, disodium calcium ethylenediaminetetraacetate is formed. The calcium ions in disodium calcium ethylenediaminetetraacetate are exchanged for ethylenediaminetetraacetic acid molecules to produce metal ions with greater affinity to extract other metal ions in palm oil; Removal mechanism of heavy metal impurities in the form of compounds: Chelating agents can form stable complexes with metal ions, causing metal ions to undergo redox reactions, thereby fixing the metal ions in the complex; Using choline chloride as a hydrogen bond acceptor and lactic acid coordinated with various donors, and introducing water to obtain a three-component eutectic compound can improve the extraction ability of the solvent and accelerate the separation of acidified palm oil from the complex.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the method of the present invention can significantly reduce the content of heavy metal ions in the separated palm oil, and the metal ion removal rate can reach more than 90% (metal ion removal rate = (before treatment-after treatment) / before treatment), and can quickly remove heavy metal ions in acidified palm oil. DETAILED DESCRIPTION

[0020] Example 1

[0021] The method for removing heavy metal ions in acidified palm oil of the present invention comprises the following steps:

[0022] (1) Preparation of eutectic solvent: 1.4 g of choline chloride and 0.9 g of lactic acid were dissolved in 1 g of pure water and mixed at 100° C. to obtain a uniform liquid phase;

[0023] (2) Preparation of the mixed treatment agent: Dissolve 1 g of disodium ethylenediaminetetraacetate and 0.5 g of heptanoic acid in 3 g of 75% ethanol aqueous solution;

[0024] (3) Detecting the heavy metal ion content in the acidified palm oil to be purified (test method: using ICP-OES for detection), the iron ion content is 40.17 ppm, the calcium ion content is 55.12 ppm, and the sodium ion content is 15.54 ppm;

[0025] (4) preheating the 50 g of the acidified palm oil to be purified, the 50 g of which contains heavy metal ions exceeding the standard limit, to 60° C., so that the palm oil can be subjected to subsequent reactions in a liquid state;

[0026] (5) adding the mixed treatment agent and the eutectic solvent successively to the preheated acidified palm oil to be purified;

[0027] (6) Maintain the oil temperature at 60°C and stir thoroughly for 20 minutes;

[0028] (7) After the reaction, 1 g of silica gel particles was added to the acidified palm oil to be purified after the reaction, and the precipitation time was 2 hours;

[0029] (8) After sedimentation, centrifuge at 6000 r for 5 minutes and take the acidified palm oil supernatant after stratification;

[0030] (9) Add 1.5 g of 200-300 mesh activated clay to the supernatant and stir for 50 min;

[0031] (10) After the adsorption is completed, the acidified palm oil adsorbed by the activated clay is filtered using a pressure-resistant filter cloth with a pore size of 5 to 10 μm to obtain purified acidified palm oil. The purified acidified palm oil is tested to have an iron ion content of 0.48 ppm, a calcium ion content of 0.96 ppm, and a sodium ion content of 0.73 ppm.

[0032] Example 1 Acidified palm oil Fe / ppm Ca / ppm Na / ppm Before treatment 40.17 55.12 15.54 After treatment 0.48 0.96 0.73 Removal rate 98.8 98.2 95.3 Settling time(s) 25 25 25

[0033] Example 2

[0034] The method for removing heavy metal ions in acidified palm oil of the present invention comprises the following steps:

[0035] (1) Preparation of eutectic solvent: 1.4 g of choline chloride and 0.9 g of lactic acid were dissolved in 1 g of pure water and mixed at 100° C. to obtain a uniform liquid phase;

[0036] (2) Preparation of the mixed treatment agent: 1.5 g of disodium ethylenediaminetetraacetate and 0.5 g of heptanoic acid were dissolved in 3 g of 80% ethanol aqueous solution;

[0037] (3) detecting the heavy metal ion content in the acidified palm oil to be purified, wherein the iron ion content is 45.23 ppm, the calcium ion content is 50.12 ppm, and the aluminum ion content is 12.45 ppm;

[0038] (4) preheating the 50 g of the acidified palm oil to be purified, the heavy metal ions of which exceed the standard limit, to 65° C., so that the palm oil can be subjected to subsequent reactions in a liquid state;

[0039] (5) adding the mixed treatment agent and the eutectic solvent successively to the preheated acidified palm oil to be purified;

[0040] (6) Maintain the oil temperature at 65°C and stir thoroughly for 25 minutes;

[0041] (7) After the reaction, 2 g of silica gel particles were added to the acidified palm oil to be purified, and the precipitation time was 2 hours;

[0042] (8) After sedimentation, centrifuge at 6000 r for 5 minutes and take the acidified palm oil supernatant after stratification;

[0043] (9) Add 1.5 g of 200-300 mesh activated clay to the supernatant and stir for 60 min;

[0044] (10) After the adsorption is completed, the acidified palm oil adsorbed by the activated clay is filtered using a pressure-resistant filter cloth with a pore size of 5 to 10 μm to obtain purified acidified palm oil. The purified acidified palm oil is tested to have an iron ion content of 0.50 ppm, a calcium ion content of 0.82 ppm, and an aluminum ion content of 0.43 ppm.

[0045] Example 2 Acidified palm oil Fe / ppm Ca / ppm Na / ppm Before treatment 45.23 50.12 12.45 After treatment 0.50 0.82 0.43 Removal rate 98.9 98.4 96.5 Settling time(s) 25 25 25

[0046] Example 3

[0047] The method for removing heavy metal ions in acidified palm oil of the present invention comprises the following steps:

[0048] (1) Preparation of eutectic solvent: 1.4 g of choline chloride and 0.9 g of lactic acid were dissolved in 1 g of pure water and mixed at 100° C. to obtain a uniform liquid phase;

[0049] (2) Preparation of the mixed treatment agent: 2 g of disodium ethylenediaminetetraacetate and 1 g of heptanoic acid were dissolved in 6 g of 85% ethanol aqueous solution;

[0050] (3) detecting the heavy metal ion content in the acidified palm oil to be purified, wherein the iron ion content is 151.25 ppm, the calcium ion content is 18.06 ppm, and the aluminum ion content is 4.58 ppm;

[0051] (4) preheating the 50 g of the acidified palm oil to be purified, the 50 g of which contains heavy metal ions exceeding the standard limit, to 70° C., so that the palm oil can be subjected to subsequent reactions in a liquid state;

[0052] (5) adding the mixed treatment agent and the eutectic solvent successively to the preheated acidified palm oil to be purified;

[0053] (6) Maintain the oil temperature at 70°C and stir thoroughly for 30 minutes;

[0054] (7) After the reaction, 2 g of silica gel particles were added to the acidified palm oil to be purified after the reaction, and the precipitation time was 3 hours;

[0055] (8) After sedimentation, centrifuge at 6000 r for 5 minutes and take the acidified palm oil supernatant after stratification;

[0056] (9) Add 2.5 g of 200-300 mesh activated clay to the supernatant and stir for 60 min;

[0057] (10) After the adsorption is completed, the acidified palm oil adsorbed by the activated clay is filtered using a pressure-resistant filter cloth with a pore size of 5 to 10 μm to obtain purified acidified palm oil. The purified acidified palm oil is tested to have an iron ion content of 1.12 ppm, a calcium ion content of 0.34 ppm, and an aluminum ion content of 0.28 ppm.

[0058]

[0059]

[0060] Example 4

[0061] The method for removing heavy metal ions in acidified palm oil of the present invention comprises the following steps:

[0062] (1) Preparation of eutectic solvent: 1.4 g of choline chloride and 0.9 g of lactic acid were dissolved in 1 g of pure water and mixed at 100° C. to obtain a uniform liquid phase;

[0063] (2) Preparation of the mixed treatment agent: 1.5 g of disodium ethylenediaminetetraacetate and 1 g of heptanoic acid were dissolved in 6 g of 80% ethanol aqueous solution;

[0064] (3) detecting the heavy metal ion content in the acidified palm oil to be purified, wherein the iron ion content is 255.56 ppm, the calcium ion content is 310.21 ppm, and the sodium ion content is 23.75 ppm;

[0065] (4) preheating the 80 g of the acidified palm oil to be purified, the heavy metal ions of which exceed the standard limit, to 60° C., so that the palm oil can be subjected to subsequent reactions in a liquid state;

[0066] (5) adding the mixed treatment agent and the eutectic solvent successively to the preheated acidified palm oil to be purified;

[0067] (6) Maintain the oil temperature at 60°C and stir thoroughly for 30 minutes;

[0068] (7) After the reaction, 2 g of silica gel particles were added to the acidified palm oil to be purified after the reaction, and the precipitation time was 2.5 hours;

[0069] (8) After sedimentation, centrifuge at 6000 r for 5 minutes and take the acidified palm oil supernatant after stratification;

[0070] (9) Add 2.5 g of 200-300 mesh activated clay to the supernatant and stir for 50 min;

[0071] (10) After the adsorption is completed, the acidified palm oil adsorbed by the activated clay is filtered using a pressure-resistant filter cloth with a pore size of 5 to 10 μm to obtain purified acidified palm oil. The purified acidified palm oil is tested to have an iron ion content of 15.16 ppm, a calcium ion content of 0.21 ppm, and a sodium ion content of 0.72 ppm.

[0072] Example 1 Acidified palm oil Fe / ppm Ca / ppm Na / ppm Before treatment 255.56 310.21 23.75 After treatment 15.16 0.21 0.72 Removal rate 94.1 99.1 96.9 Settling time(s) 25 25 25

[0073] Example 5

[0074] The method for removing heavy metal ions in acidified palm oil of the present invention comprises the following steps:

[0075] (1) Preparation of eutectic solvent: 1.4 g of choline chloride and 0.9 g of lactic acid were dissolved in 1 g of pure water and mixed at 100° C. to obtain a uniform liquid phase;

[0076] (2) Preparation of the mixed treatment agent: 3 g of disodium ethylenediaminetetraacetate and 1.6 g of heptanoic acid were dissolved in 9 g of 75% ethanol aqueous solution;

[0077] (3) detecting the heavy metal ion content in the acidified palm oil to be purified, wherein the iron ion content is 245 ppm, the calcium ion content is 375 ppm, and the aluminum ion content is 81 ppm;

[0078] (4) preheating the 80 g of the acidified palm oil to be purified, the heavy metal ions of which exceed the standard limit, to 60° C., so that the palm oil can be subjected to subsequent reactions in a liquid state;

[0079] (5) adding the mixed treatment agent and the eutectic solvent successively to the preheated acidified palm oil to be purified;

[0080] (6) Maintain the oil temperature at 60°C and stir thoroughly for 40 minutes;

[0081] (7) After the reaction, 3 g of silica gel particles were added to the acidified palm oil to be purified after the reaction, and the precipitation time was 2 hours;

[0082] (8) After sedimentation, centrifuge at 6000 r for 5 minutes and take the acidified palm oil supernatant after stratification;

[0083] (9) Add 4.0 g of 200-300 mesh activated clay to the supernatant and stir for 60 min;

[0084] (10) After the adsorption is completed, the acidified palm oil adsorbed by the activated clay is filtered using a pressure-resistant filter cloth with a pore size of 5 to 10 μm to obtain purified acidified palm oil. The purified acidified palm oil is tested to have an iron ion content of 23.91 ppm, a calcium ion content of 5.62 ppm, and an aluminum ion content of 1.43 ppm.

[0085] Example 1 Acidified palm oil Fe / ppm Ca / ppm Na / ppm Before treatment 245 375 81 After treatment 23.91 5.62 1.43 Removal rate 90.2 98.5 98.2 Settling time(s) 25 25 25

[0086] Example 6

[0087] The method for removing heavy metal ions in acidified palm oil of the present invention comprises the following steps:

[0088] (1) Preparation of eutectic solvent: 2.8 g of choline chloride and 1.8 g of lactic acid were dissolved in 2 g of pure water and mixed at 100° C. to obtain a uniform liquid phase;

[0089] (2) Preparation of the mixed treatment agent: 1.5 g of disodium ethylenediaminetetraacetate and 0.5 g of heptanoic acid were dissolved in 5 g of 80% ethanol aqueous solution;

[0090] (3) detecting the heavy metal ion content in the acidified palm oil to be purified, wherein the iron ion content is 139 ppm, the calcium ion content is 56 ppm, and the sodium ion content is 23 ppm;

[0091] (4) preheating the 50 g of the acidified palm oil to be purified, the 50 g of which contains heavy metal ions exceeding the standard limit, to 60° C., so that the palm oil can be subjected to subsequent reactions in a liquid state;

[0092] (5) adding the mixed treatment agent and the eutectic solvent successively to the preheated acidified palm oil to be purified;

[0093] (6) Maintain the oil temperature at 60°C and stir thoroughly for 20 minutes;

[0094] (7) After the reaction, 2 g of silica gel particles were added to the acidified palm oil to be purified, and the precipitation time was 2 hours;

[0095] (8) After sedimentation, centrifuge at 6000 r for 5 minutes and take the acidified palm oil supernatant after stratification;

[0096] (9) Add 2.5 g of 200-300 mesh activated clay to the supernatant and stir for 60 min;

[0097] (10) After the adsorption is completed, the acidified palm oil adsorbed by the activated clay is filtered using a pressure-resistant filter cloth with a pore size of 5 to 10 μm to obtain purified acidified palm oil. The purified acidified palm oil is tested to have an iron ion content of 1.25 ppm, a calcium ion content of 0.52 ppm, and a sodium ion content of 0.79 ppm.

[0098] Example 1 Acidified palm oil Fe / ppm Ca / ppm Na / ppm Before treatment 139 56 23 After treatment 1.25 0.52 0.79 Removal rate 99.1 99.1 96.5 Settling time(s) 20 20 20

[0099] Comparative Example 1

[0100] A method for removing heavy metal ions in acidified palm oil comprises the following steps:

[0101] (1) Preparation of the mixed treatment agent: Dissolve 1 g of disodium ethylenediaminetetraacetate and 0.5 g of heptanoic acid in 3 g of 75% ethanol aqueous solution;

[0102] (2) Detecting the heavy metal ion content in the acidified palm oil to be purified (test method: using ICP-OES for detection), the iron ion content is 40.17 ppm, the calcium ion content is 55.12 ppm, and the sodium ion content is 15.54 ppm;

[0103] (3) preheating the 50 g of the acidified palm oil to be purified, the 50 g of which contains heavy metal ions exceeding the standard limit, to 60° C., so that the palm oil can be subjected to subsequent reactions in a liquid state;

[0104] (4) adding a mixed treatment agent to the preheated acidified palm oil to be purified;

[0105] (5) Maintain the oil temperature at 60°C and stir thoroughly for 20 minutes;

[0106] (6) After the reaction, 1 g of silica gel particles was added to the acidified palm oil to be purified after the reaction, and the precipitation time was 2 hours;

[0107] (7) After sedimentation, centrifuge at 6000 r for 5 minutes and take the acidified palm oil supernatant after stratification;

[0108] (8) Add 1.5 g of 200-300 mesh activated clay to the supernatant and stir for 50 min;

[0109] (9) After the adsorption is completed, the acidified palm oil adsorbed by the activated clay is filtered using a pressure-resistant filter cloth with a pore size of 5 to 10 μm to obtain purified acidified palm oil. The purified acidified palm oil is tested to have an iron ion content of 8.23 ​​ppm, a calcium ion content of 10.69 ppm, and a sodium ion content of 3.53 ppm.

[0110] Comparative Example 1 Acidified palm oil Fe / ppm Ca / ppm Na / ppm Before treatment 40.17 55.12 15.54 After treatment 8.23 10.69 3.53 Removal rate 79.5 80.6 77.3 Settling time(s) 180 180 180

[0111] Comparative Example 2

[0112] A method for removing heavy metal ions in acidified palm oil comprises the following steps:

[0113] (1) Preparation of eutectic solvent: Dissolve 1.4 g of choline chloride in 1 g of pure water and mix at 100° C. to obtain a uniform liquid phase;

[0114] (2) Preparation of the mixed treatment agent: Dissolve 1 g of disodium ethylenediaminetetraacetate and 0.5 g of heptanoic acid in 3 g of 75% ethanol aqueous solution;

[0115] (3) Detecting the heavy metal ion content in the acidified palm oil to be purified (test method: using ICP-OES for detection), the iron ion content is 40.17 ppm, the calcium ion content is 55.12 ppm, and the sodium ion content is 15.54 ppm;

[0116] (4) preheating the 50 g of the acidified palm oil to be purified, the 50 g of which contains heavy metal ions exceeding the standard limit, to 60° C., so that the palm oil can be subjected to subsequent reactions in a liquid state;

[0117] (5) adding the mixed treatment agent and the eutectic solvent successively to the preheated acidified palm oil to be purified;

[0118] (6) Maintain the oil temperature at 60°C and stir thoroughly for 20 minutes;

[0119] (7) After the reaction, 1 g of silica gel particles was added to the acidified palm oil to be purified after the reaction, and the precipitation time was 2 hours;

[0120] (8) After sedimentation, centrifuge at 6000 r for 5 minutes and take the acidified palm oil supernatant after stratification;

[0121] (9) Add 1.5 g of 200-300 mesh activated clay to the supernatant and stir for 50 min;

[0122] (10) After the adsorption is completed, the acidified palm oil adsorbed by the activated clay is filtered using a pressure-resistant filter cloth with a pore size of 5 to 10 μm to obtain purified acidified palm oil. The purified acidified palm oil is tested to have an iron ion content of 6.12 ppm, a calcium ion content of 8.89 ppm, and a sodium ion content of 2.56 ppm.

[0123] Comparative Example 2 Acidified palm oil Fe / ppm Ca / ppm Na / ppm Before treatment 40.17 55.12 15.54 After treatment 6.12 8.89 2.56 Removal rate 84.76 83.87 83.53 Settling time(s) 170 170 170

[0124] By comparing Comparative Example 1 with Example 1, it can be seen that if only a mixed solvent is added to the preheated acidified palm oil without adding a eutectic solvent, the extraction rate of metal ions is much lower than the extraction rate after the eutectic solvent and the mixed solvent are mixed in Example 1, and the sedimentation time is much longer than that in Example 1; by comparing Comparative Example 2 with Example 1, it can be seen that only choline chloride is added to prepare the eutectic solvent, and a three-component eutectic solvent cannot be formed due to the lack of a hydrogen bond donor, so the extraction rate of metal ions is also much lower than that in Example 1, and the sedimentation time is also much longer than that in Example 1. The method of the present invention can accelerate the precipitation rate of metal ions, enable the dissolved heavy metal ions to quickly generate more precipitates, greatly reduce the sedimentation time, and thus improve the extraction rate of heavy metal ions in acidified palm oil.

Claims

1. A method for removing heavy metal ions from acidified palm oil, characterized in that: The steps include: (1) adding a mixed treatment agent and a eutectic solvent to the preheated acidified palm oil to be purified in sequence, and reacting at high temperature; (2) adding a precipitation aid to the mixed solution after the reaction in step (1), taking out the supernatant after sufficient precipitation, adding an adsorbent thereto, and filtering to obtain purified acidified palm oil after adsorption.

2. The removal method according to claim 1, characterized in that: In step (1), the mixed treatment agent is prepared by the following method, specifically: disodium ethylenediaminetetraacetate, heptanoic acid and ethanol aqueous solution are mixed to obtain the mixed treatment agent.

3. The removal method according to claim 2, characterized in that: The volume concentration of the ethanol aqueous solution is 75-80%.

4. The removal method according to claim 2, characterized in that: The mixing mass ratio of disodium ethylenediaminetetraacetate, heptanoic acid and ethanol aqueous solution is 1-3:0.5-1.6:3-9.

5. The removal method according to claim 1, characterized in that: The added amount of disodium ethylenediaminetetraacetate is 1-4% of the mass of the acidified palm oil to be purified; the added amount of heptanoic acid is 1-2% of the mass of the acidified palm oil to be purified; and the added amount of ethanol aqueous solution is 6-12% of the mass of the acidified palm oil to be purified.

6. The removal method according to claim 1, characterized in that: In step (1), the eutectic solvent is prepared by the following method, specifically: mixing choline chloride, lactic acid and water at a temperature not lower than 100° C. to obtain a eutectic solvent.

7. The removal method according to claim 6, characterized in that: The mixing molar ratio of choline chloride, lactic acid and water is 1.0:1.0:5.5-6.

8. The removal method according to claim 1, characterized in that: In step (1), the preheating temperature of the acidified palm oil is 60-70° C.; the reaction temperature is 60-70° C.; and the reaction time is 20-40 min.

9. The removal method according to claim 1, characterized in that: In step (2), the sedimentation aid is silica gel particles; the mass ratio of the sedimentation aid to the acidified palm oil to be purified is 1-3:50-80; and the sedimentation aid time is 2-3 hours.

10. The removal method according to claim 1, characterized in that: In step (2), the adsorbent is activated white clay of 200-300 mesh, the mass ratio of the adsorbent to the acidified palm oil to be purified is 1.5-4:50-80; and the adsorption time is 50-60 min.

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