An activated carbon for adsorbing cholesterol and a preparation method thereof

Abstract

The present invention discloses an activated carbon for adsorbing cholesterol and its preparation method, which relates to the field of material preparation. The Langmuir specific surface area of the activated carbon of passion fruit peel after being soaked in an activator and activated at high temperature is 838.87 m² / g, while the Langmuir specific surface area of the unactivated activated carbon is 6.27 m² / g, and the specific surface area after activation is increased by about 133 times. The activated carbon has small pore sizes for adsorption and desorption. After activation, the average adsorption pore size is 1.99 nm, and the average desorption pore size is 1.96 nm. The process conditions of the present invention are simple, the required carbonization time and activation time are short, and the energy consumption is low. The present invention efficiently utilizes passion fruit waste to prepare activated carbon with low cost, and can rapidly and effectively adsorb cholesterol at a concentration of 50-100 mg / L.

Description

Technical Field

[0001] The present invention relates to the field of material preparation, and particularly to an activated carbon for adsorbing cholesterol and a preparation method thereof. Background Art

[0002] The peel waste of passion fruit is rich in biodegradable organic components, which will produce an intolerable stench during the decomposition process. In order to minimize the environmental impact of waste, the recovery of health-beneficial compounds and their conversion into other useful biomasses have become the focus of researchers. The potential uses of fruit waste can be divided into food and non-food uses. Food uses are in the aspects of obesity treatment, food additives, and edible coatings and films. The main use of fruit waste in non-food applications is as a biosorbent to remove pollutants, heavy metals, and dyes in wastewater.

[0003] Dyes and heavy metals are the main pollutants because they come from a large number of industries such as textiles, dyeing, batteries, leather, fertilizers, chemicals, mining, metallurgy, oil refining, and many other industries. These industries discharge wastewater containing high concentrations of dyes and heavy metal ions into the environment. Substances harmful to human health cause various diseases such as skin irritation, allergies, tumors, headaches, and respiratory problems. It also damages the aquatic ecosystem by reducing the light entering the water. The effective and low-cost removal of dyes and heavy metals in wastewater remains a huge challenge for researchers. At present, the activated carbon adsorption method has been widely used for the removal of these toxic pollutants. In order to improve the adsorption performance of activated carbon, physical, chemical, and biological modifications have been studied. The literature shows that chemically modified activated carbon has the greatest adsorption capacity for dyes and heavy substances in aqueous solutions. Chemical modifications, including acids, bases, and impregnation, have been widely studied due to the availability of reagents, ease of modification, and surface functional group tuning facilities. Adsorption, precipitation, membrane filtration, chemical oxidation, ion exchange, and electrolysis methods have been used to treat wastewater containing dyes and heavy metals. However, most treatment processes are costly, require long treatment times, and generate additional waste treatment problems. Adsorption is a promising technology because it is low-cost, simple to operate, and efficient. Impregnation with suitable chemicals can improve the adsorption capacity of activated carbon for removing harmful substances.

[0004] Nutritional guidelines for reducing the risk of cardiovascular disease and achieving optimal plasma lipoprotein profiles include restricting dietary cholesterol intake. High cholesterol can be harmful to blood vessels, the heart, and the gallbladder. High cholesterol can lead to atherosclerosis of the arteries and may be accompanied by heart diseases when it occurs. The harm to the body's liver generally causes fatty liver, resulting in abnormal metabolism of liver fat. The related harm to the gallbladder affects the secretion of bile, leading to the formation of cholesterol crystals in the gallbladder and the formation of gallstones due to cholesterol deposition in the gallbladder. Foods such as eggs and animal livers have relatively high cholesterol content. Reducing the cholesterol content in food is more likely to improve the quality of the diet and promote cardiovascular health. Using activated carbon to adsorb cholesterol is a novel technology with great development potential. Summary of the Invention

[0005] In view of this, the present invention provides an activated carbon for adsorbing cholesterol and a preparation method thereof. By subjecting passion fruit peels to high-temperature carbonization, soaking in an activating agent, and high-temperature activation, a modified activated carbon is obtained. This activated carbon can be used to adsorb cholesterol, improve the quality of the diet, and enhance the cardiovascular health of the elderly and overweight groups.

[0006] The technical solution of the present invention is specifically as follows:

[0007] A preparation method of an activated carbon for adsorbing cholesterol, comprising the following steps:

[0008] (1) Raw material preparation: drying passion fruit peels, crushing them, and sieving to obtain passion fruit peel powder;

[0009] (2) High-temperature carbonization: carbonizing the passion fruit peel powder at 400 - 500 °C for 2 h to obtain carbonized passion fruit peel particles;

[0010] (3) Soaking in the activating agent: immersing the carbonized passion fruit peel particles in aqua regia to obtain a mixed product;

[0011] (4) High-temperature activation: activating the mixed product at 600 - 1000 °C for 90 min to obtain a crude product, washing the crude product to neutral, and drying to obtain the activated carbon for adsorbing cholesterol.

[0012] Preferably, in step (1), the sieving condition is: sieving through a 50-mesh sieve.

[0013] Preferably, in step (2), the passion fruit peel powder is carbonized at 500 °C for 2 h,

[0014] During high-temperature carbonization, the heating rate is 10 °C / min.

[0015] Preferably, in step (3), the volume ratio of hydrochloric acid to nitric acid in aqua regia is 3:1.

[0016] The impregnation ratio of the carbonized passion fruit peel particles to aqua regia is 1:5, and the immersion time is 12 h.

[0017] Preferably, in step (4), the mixed product is activated at 800 °C for 90 min.

[0018] During high-temperature activation, the heating rate is 10 °C / min.

[0019] After activation under the condition of 800 °C, it has the maximum adsorption capacity for methylene blue. The activated carbon of passion fruit peel after activation at 800 °C is suitable for adsorbing samples with a cholesterol content of less than 100 mg / L.

[0020] The present invention also provides activated carbon for adsorbing cholesterol prepared by the preparation method described above.

[0021] The present invention also provides an application of the activated carbon, and the application is any one of the following:

[0022] (1) Application in the preparation of a cholesterol adsorbent;

[0023] (2) Application in a fuel adsorbent in industrial wastewater.

[0024] Preferably, when applied in the preparation of a cholesterol adsorbent, the cholesterol adsorbent adsorbs cholesterol at a content of 50-200 mg / L. More preferably, the cholesterol adsorbent adsorbs cholesterol at a content of 50-100 mg / L.

[0025] As the cholesterol content increases, the adsorption effect of the activated carbon of passion fruit peel decreases. In this way, not all cholesterol in the liquid food will be adsorbed, and the normal cholesterol supply of the human body can be maintained.

[0026] Advantages of the present invention:

[0027] (1) The Langmuir specific surface area of the activated carbon of passion fruit peel after being soaked with an activator and high-temperature activated in the present invention is 838.87 m 2 / g, and the Langmuir specific surface area of the non-activated activated carbon is 6.27 m 2 / g. After activation, the specific surface area increases by about 133 times.

[0028] (2) The pore diameters of the adsorption and desorption of the activated carbon prepared in the present invention are small. After activation, the average adsorption pore diameter is 1.99 nm, and the average desorption pore diameter is 1.96 nm.

[0029] (3) The process conditions of the present invention are simple, the required carbonization time and activation time are short, and the energy consumption is low.

[0030] (4) The present invention efficiently utilizes passion fruit waste to prepare low-cost activated carbon.

[0031] (5) The passion fruit peel activated carbon prepared by the present invention can rapidly and effectively adsorb cholesterol at a concentration of 50 - 100 mg / L. Description of the Drawings

[0032] Figure 1 It is a micrograph of the sample (S2 sample) obtained by the treatment in step S2 of Example 3.

[0033] Figure 2 It is a micrograph of the sample (S5 sample) obtained by the treatment in step S5 of Example 3.

[0034] Figure 3 It is a micrograph of the sample obtained by the treatment in step S5 of Comparative Example 1.

[0035] Figure 4 It is an industrial activated carbon sample.

[0036] Figure 5 It is the adsorption performance of the samples of Examples 1 - 5 for dyes. Among them, (A) is the adsorption performance for methylene blue; (B) is the adsorption performance for crystal violet; (C) is the adsorption performance for phenol; the "blank group" refers to Comparative Example 2. The same English labels appearing on the bar graph represent no significant difference between each other (P > 0.05).

[0037] Figure 6 It is the adsorption performance of the samples in the comparative examples for dyes; among them, (A) is the adsorption performance of the sample obtained by the treatment in step S5 of Comparative Example 1 for methylene blue, crystal violet, and phenol; (B) is the adsorption performance of industrial activated carbon for methylene blue, crystal violet, and phenol.

[0038] Figure 7 It is the adsorption rate of different samples for different concentrations of cholesterol. (A) is the sample of Comparative Example 2, (B) is the S5 sample of Example 3, (C) is the S5 sample of Comparative Example 1, (D) is the industrial activated carbon sample. The same English labels appearing on the bar graph represent no significant difference between each other (P > 0.05). Detailed Embodiments

[0039] Main experimental reagents and experimental equipment:

[0040] Experimental reagents and raw materials: concentrated hydrochloric acid, concentrated nitric acid, methylene blue, crystal violet, phenol, cholesterol, cholesterol kit (Solarbio Science & Technology Co., Ltd.); industrial activated carbon (Shanghai Aladdin Biochemical Technology Co., Ltd., product number: 7440 - 44 - 0), and the passion fruit peels are sourced from local picking in Guilin, Guangxi.

[0041] Experimental equipment: microplate reader, electrothermal blast drying oven, tubular furnace, crucible, electronic precision balance, nitrogen cylinder, glassware, etc.

[0042] Example 1

[0043] In the activation stage, activation is carried out at 600 °C for 90 min. The specific implementation method is as follows:

[0044] S1. Raw material preparation: Dry, crush, and sieve the passion fruit peel, and obtain passion fruit peel powder with a particle size of 50 mesh after sieving;

[0045] S2. High-temperature carbonization: Place the passion fruit peel powder obtained in step S1 in a muffle furnace for carbonization pretreatment. The carbonization temperature is 500 °C, the carbonization time is 2 h, and the heating rate is 10 °C / min to obtain carbonized passion fruit peel particles;

[0046] S3. Activator immersion: Take the carbonized passion fruit peel powder particles obtained in step S2 and mix and impregnate them with a hydrochloric acid and nitric acid mixture (volume ratio 3:1). The impregnation ratio (mass ratio) is 1:5, and the impregnation time is 12 h;

[0047] S4. High-temperature activation: Put the mixed product of step S3 into a muffle furnace for activation. Among them, the activation temperature is raised to 700 °C at a heating rate of 10 °C / min, and the activation time is 90 min. Finally, cool the muffle furnace to 50 °C and then take out the product to obtain a crude product;

[0048] S5. Finished product: Wash and dry the crude product of step S4, and sieve to obtain an activated carbon product with a particle size of 200 mesh.

[0049] Example 2

[0050] In the activation stage, activation is carried out at 700 °C for 90 min. The specific implementation method is as follows:

[0051] S1. Raw material preparation: Dry, crush, and sieve the passion fruit peel, and obtain passion fruit peel powder with a particle size of 50 mesh after sieving;

[0052] S2. High-temperature carbonization: Place the passion fruit peel powder obtained in step S1 in a muffle furnace for carbonization pretreatment. The carbonization temperature is 500 °C, the carbonization time is 2 h, and the heating rate is 10 °C / min to obtain carbonized passion fruit peel particles;

[0053] S3. Activator immersion: Take the carbonized passion fruit peel powder particles obtained in step S2 and mix and impregnate them with a hydrochloric acid and nitric acid mixture (volume ratio 3:1). The impregnation ratio (mass ratio) is 1:5, and the impregnation time is 12 h;

[0054] S4. High-temperature activation: Put the mixed product from step S3 into a muffle furnace for activation. Raise the activation temperature to 700 °C at a heating rate of 10 °C / min, with an activation time of 90 min. Finally, cool the muffle furnace to 50 °C and take out the product to obtain the crude product;

[0055] S5. Finished product: Wash and dry the crude product from step S4, and sieve it to obtain an activated carbon product with a mesh size of 200.

[0056] Example 3

[0057] In the activation stage, activation is carried out at 800 °C for 90 min. The specific implementation method is as follows:

[0058] S1. Raw material preparation: Dry, crush, and sieve the passion fruit peel to obtain passion fruit peel powder with a particle size of 50 mesh;

[0059] S2. High-temperature carbonization: Put the passion fruit peel powder obtained in step S1 into a muffle furnace for preliminary carbonization treatment. The carbonization temperature is 500 °C, the carbonization time is 2 h, and the heating rate is 10 °C / min to obtain carbonized passion fruit peel particles;

[0060] S3. Activator immersion: Take the carbonized passion fruit peel powder particles from step S2 and mix and impregnate them with a hydrochloric acid and nitric acid mixture (volume ratio 3:1), with an impregnation ratio of 1:5 and an impregnation time of 12 h;

[0061] S4. High-temperature activation: Put the mixed product from step S3 into a muffle furnace for activation. Raise the activation temperature to 800 °C at a heating rate of 10 °C / min, with an activation time of 90 min. Finally, cool the muffle furnace to 50 °C and take out the product to obtain the crude product;

[0062] S5. Finished product: Wash and dry the crude product from step S4, and sieve it to obtain an activated carbon product with a mesh size of 200.

[0063] The Langmuir specific surface area of the carbonized passion fruit peel carbon obtained in S2 is 6.27 m 2 / g;

[0064] The Langmuir specific surface area of the passion fruit peel activated carbon obtained in S5 is 956.21 m 2 / g.

[0065] Example 4

[0066] In the activation stage, activation is carried out at 900 °C for 90 min. The specific implementation method is as follows:

[0067] S1. Raw material preparation: Dry, crush, and sieve the passion fruit peel to obtain passion fruit peel powder with a particle size of 50 mesh;

[0068] S2. High-temperature carbonization: Place the passion fruit peel powder obtained in step S1 in a muffle furnace for initial carbonization treatment. The carbonization temperature is 500 °C, the carbonization time is 2 h, and the heating rate is 10 °C / min to obtain carbonized passion fruit peel particles.

[0069] S3. Activator immersion: Take the carbonized passion fruit peel powder particles obtained in step S2 and mix and impregnate them with a hydrochloric acid and nitric acid mixture (volume ratio 3:1). The impregnation ratio is 1:5, and the impregnation time is 12 h.

[0070] S4. High-temperature activation: Put the mixed product of step S3 into a muffle furnace for activation. Raise the activation temperature to 800 °C at a heating rate of 10 °C / min, and the activation time is 90 min. Finally, cool the muffle furnace to 50 °C and then take out the product to obtain a crude product.

[0071] S5. Finished product: Wash and dry the crude product of step S4, and sieve it to obtain an activated carbon product with a mesh size of 200.

[0072] Example 5

[0073] In the activation stage, activation is carried out at 1000 °C for 90 min. The specific implementation method is as follows:

[0074] S1. Raw material preparation: Dry, crush, and sieve the passion fruit peel, and sieve to obtain passion fruit peel powder with a particle size of 50 mesh.

[0075] S2. High-temperature carbonization: Place the passion fruit peel powder obtained in step S1 in a muffle furnace for initial carbonization treatment. The carbonization temperature is 500 °C, the carbonization time is 2 h, and the heating rate is 10 °C / min to obtain carbonized passion fruit peel particles.

[0076] S3. Activator immersion: Take the carbonized passion fruit peel powder particles obtained in step S2 and mix and impregnate them with a hydrochloric acid and nitric acid mixture (volume ratio 3:1). The impregnation ratio is 1:5, and the impregnation time is 12 h.

[0077] S4. High-temperature activation: Put the mixed product of step S3 into a muffle furnace for activation. Raise the activation temperature to 800 °C at a heating rate of 10 °C / min, and the activation time is 90 min. Finally, cool the muffle furnace to 50 °C and then take out the product to obtain a crude product.

[0078] S5. Finished product: Wash and dry the crude product of step S4, and sieve it to obtain an activated carbon product with a mesh size of 200.

[0079] Comparative Example 1

[0080] Compare with the preparation method of a passion fruit peel-based activated carbon in the patent application with the publication number CN115140735A.

[0081] S1. Raw material preparation: First, wash the selected whole passion fruit to remove surface dirt, dry the passion fruit peel until the water content is about 5%, the drying temperature is 80 ± 5 °C, crush the dried product, and pass through a 50-mesh sieve to obtain passion fruit peel particles.

[0082] S2. High-temperature carbonization process: Place the passion fruit peel particles obtained in step S1 in a muffle furnace for carbonization pretreatment. The muffle furnace is heated from room temperature 20 - 30 °C to 800 °C at a heating rate of 10 °C / min, hold for carbonization for 4 h, and finally cool to room temperature to obtain carbonized passion fruit peel particles.

[0083] S3. Activator soaking: Mix the carbonized passion fruit peel powder particles obtained in step S2 with an activator aqueous solution. The activator aqueous solution is prepared from phosphoric acid and potassium hydroxide. The phosphoric acid concentration in the activator aqueous solution is 30% and the potassium hydroxide concentration is 0.1 mol / L; the impregnation ratio (mass ratio) of the passion fruit peel powder particles to the activator water is 1:4. After stirring evenly, soak at 25 ± 2 °C for 24 h to obtain a mixed product.

[0084] S4. High-temperature activation: Put the activated mixed product obtained in step S3 into a muffle furnace for activation. Starting from room temperature 20 - 30 °C, raise the activation temperature to 400 °C at a heating rate of 5 °C / min and hold for activation for 4 h; finally, cool the muffle furnace to 50 °C and then take out the product to obtain a crude product.

[0085] S5. Finished product: Wash and dry the crude product obtained in step S4, and sieve to obtain the target activated carbon product; specific operation: Repeatedly rinse the prepared crude product with distilled water to remove other inorganic substances, then dry to a constant weight at 65 ± 2 °C, and pass through a 200-mesh sieve to obtain the passion fruit peel-based activated carbon product.

[0086] The Langmuir specific surface area of the finished activated carbon obtained in step S5 is 4.35 m 2 / g.

[0087] Compared with the sample under the synergistic action of aqua regia and 800 °C in Example 3, the sample in Example 3 has a larger Langmuir specific surface area (956.21 m 2 / g).

[0088] Comparative Example 2

[0089] In the activation stage, activation is carried out at 800 °C for 90 min. The specific implementation method is as follows:

[0090] S1. Raw material preparation: Dry, crush, and sieve the passion fruit peel. After sieving, obtain passion fruit peel powder with a particle size of 50 mesh.

[0091] S2. High-temperature carbonization: Place the passion fruit peel powder obtained in step S1 in a muffle furnace for carbonization pretreatment. The carbonization temperature is 500 °C, the carbonization time is 2 h, and the heating rate is 10 °C / min to obtain carbonized passion fruit peel particles.

[0092] S3. Activator immersion: Take the carbonized passion fruit peel powder particles obtained in step S2 and mix and impregnate them with distilled water. The impregnation ratio is 1:5, and the impregnation time is 12 h.

[0093] S4. High-temperature activation: Put the mixed product in step S3 into a muffle furnace for activation. Raise the activation temperature to 800 °C at a heating rate of 10 °C / min, and the activation time is 90 min. Finally, cool the muffle furnace to 50 °C and then take out the product to obtain the crude product.

[0094] S5. Finished product: Wash and dry the crude product in step S4, and sieve to obtain an activated carbon product with a particle size of 200 mesh.

[0095] Test Example 1

[0096] 1. Morphology determination

[0097] Take the samples obtained in step S2 of Example 3, the samples obtained in step S5 of Example 3, the samples obtained in step S5 of Comparative Example 1, and the industrial activated carbon sample (Shanghai Yien Chemical Technology Co., Ltd., product number: 7440-44-0) for scanning electron microscopy photography. As Figures 1 to 4 shown, it can be seen that under the synergistic action of 800 °C and aqua regia, the fiber structure of the passion fruit peel is eroded by high temperature and corrosive acid, and more pores are generated on the surface. The use of phosphoric acid, potassium hydroxide, and high-temperature treatment in the comparative example cannot achieve such an effect.

[0098] 2. Adsorption performance test:

[0099] Prepare 100 mg / L methylene blue solution, 100 mg / L crystal violet solution, and 100 mg / L phenol solution respectively; and use the S2 sample and S5 sample in Example 3, the S5 sample in Comparative Example 1, and the industrial activated carbon sample to test their adsorption effects after adsorbing for 30 min at room temperature (25 °C).

[0100] According to Figure 5 and Figure 6 results, the maximum adsorption capacity of the S2 sample in Example 3 for methylene blue is 41.32 ± 3.32 mg / g; for crystal violet is 190.58 ± 6.57 mg / g; for phenol is 73.78 ± 0.58 mg / g.

[0101] The maximum adsorption capacity of the S5 sample in Example 3 for methylene blue was 98.01 ± 1.24 mg / g; for crystal violet was 310.13 ± 4.20 mg / g; for phenol was 89.10 ± 0.61 mg / g.

[0102] The maximum adsorption capacity of the S5 sample in Comparative Example 1 for methylene blue was 24.58 ± 3.34 mg / g; for crystal violet was 19.93 ± 4.97 mg / g; for phenol was 28.68 ± 1.04 mg / g.

[0103] The maximum adsorption capacity of the industrial activated carbon sample for methylene blue was 285.66 ± 7.50 mg / g; for crystal violet was 597.27 ± 1.16 mg / g; for phenol was 84.61 ± 1.11 mg / g.

[0104] The test results of the full-automatic specific surface area and porosity analyzer are shown as follows:

[0105] (1) The average BJH adsorption pore diameter of the S2 sample in Example 3 was 10.17 nm, and the average BJH desorption pore diameter was 8.43 nm;

[0106] (2) The average BJH adsorption pore diameter of the S5 sample in Example 3 was 4.26 nm, and the average BJH desorption pore diameter was 3.87 nm.

[0107] (3) The average BJH adsorption pore diameter of the S5 sample in Comparative Example 1 was 5.07 nm, and the average BJH desorption pore diameter was 5.18 nm;

[0108] (4) The average BJH adsorption pore diameter of the industrial activated carbon was 6.47 nm, and the average BJH desorption pore diameter was 6.36 nm.

[0109] 3. Cholesterol adsorption performance test

[0110] Cholesterol solutions with concentrations of 50, 100, 200, 400, and 800 mg / L were prepared, and the S5 sample in Example 3, the S5 sample in Comparative Example 1, the activated carbon sample obtained in Comparative Example 2, and the industrial activated carbon sample were used to test their adsorption effects after adsorption at room temperature (25°C) for 30 min.

[0111] According to Figure 7 In the adsorption comparison chart of cholesterol shown, it can be found that the passion fruit peel activated carbon activated by aqua regia at 800°C is suitable for adsorbing samples with cholesterol content below 100 mg / L. As the cholesterol content increases, the adsorption effect of the passion fruit peel activated carbon decreases.

[0112] It should be particularly noted that in this embodiment, the obtained passion fruit activated carbon is suitable for adsorbing cholesterol at a concentration of 50-100 mg / L. Industrial activated carbon is not suitable for adsorbing cholesterol because it may absorb all the cholesterol in food. Mammals, including humans, need cholesterol to maintain normal metabolism. Cholesterol is an essential cell membrane regulator, a precursor for the synthesis of bile acids (necessary for the formation of fat emulsions and intestinal absorption), and a substrate for the synthesis of steroid hormones (including estrogen and androgen). Partial adsorption (adsorption rate > 60%) of cholesterol in food can reduce the total cholesterol content ingested, which can reduce the risk of cardiovascular diseases. Reducing cholesterol content does not mean completely removing cholesterol from food. In addition, industrial activated carbon may contain other harmful substances to the human body. Passion fruit peel activated carbon is a natural renewable resource and is safer.

Claims

1. A preparation method of activated carbon for adsorbing cholesterol, characterized in that, It includes the following steps: (1) Raw material preparation: Dry the passion fruit peel, crush it and sieve it to obtain passion fruit peel powder; (2) High-temperature carbonization: Carbonize the passion fruit peel powder at 400-500 °C for 1-2 h to obtain carbonized passion fruit peel particles; (3) Activator immersion: Immerse the carbonized passion fruit peel particles in aqua regia to obtain a mixed product; (4) High-temperature activation: Activate the mixed product at 600-1000 °C for 90 min to obtain a crude product. Wash the crude product to neutral, dry it, and obtain the activated carbon for adsorbing cholesterol.

2. The preparation method of the activated carbon for adsorbing cholesterol according to claim 1, wherein, In step (1), the sieving condition is: passing through a 50-mesh sieve.

3. The preparation method of the activated carbon for adsorbing cholesterol according to claim 1, characterized in that, In step (2), carbonize the passion fruit peel powder at 500 °C for 2 h, During high-temperature carbonization, the heating rate is 10 °C / min.

4. The preparation method of the activated carbon for adsorbing cholesterol according to claim 1, wherein The impregnation ratio of the carbonized passion fruit peel particles to aqua regia is 1:5, and the immersion time is 12 h.

5. The preparation method of the activated carbon for adsorbing cholesterol according to claim 1, wherein In step (4), activate the mixed product at 800 °C for 90 min, During high-temperature activation, the heating rate is 10 °C / min.

6. Activated carbon for adsorbing cholesterol prepared by the preparation method according to any one of claims 1 to 5.

7. An application of the activated carbon according to claim 6, wherein the application is any one of the following: (1) Application in the preparation of a cholesterol adsorbent; (2) Application in a dye adsorbent for industrial wastewater.

8. The application according to claim 7, characterized in that, When applied in the preparation of a cholesterol adsorbent, the cholesterol content adsorbed by the cholesterol adsorbent is 50-200 mg / L.

9. The application according to claim 8, characterized in that When applied in the preparation of a cholesterol adsorbent, the cholesterol content adsorbed by the cholesterol adsorbent is 50-100 mg / L.

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