Preparation method and application of porous activated carbon

Abstract

The invention discloses a preparation method and application of porous activated carbon, and the preparation method of the porous activated carbon comprises the following steps: mixing alginic acid and ammonium chloride to obtain mixed particle powder; grinding the mixed particle powder to obtain mixed fine powder; and carrying out heat treatment on the mixed fine powder in a protective gas atmosphere to prepare the porous activated carbon. Alginic acid and ammonium chloride are used as raw materials, the porous activated carbon material is prepared through mixing, grinding and heat treatment, the preparation process is simple and easy to implement, the cost is low, industrial mass production is easy to achieve, when the porous activated carbon material is used for physical adsorption removal of excessive benzo (a) pyrene in vegetable oil, the adsorption performance is excellent, the removal rate of benzo (a) pyrene reaches 90% or above, and the porous activated carbon material is suitable for industrial production. And the content of benzo (a) pyrene in the treated vegetable oil can reach the limit standard.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a preparation method of porous activated carbon and application thereof. Background Art

[0002] Benzo(a)pyrene is a polycyclic aromatic hydrocarbon compound and one of the top three strong carcinogens in the world. Benzo(a)pyrene is formed by thermal cracking, cyclization and polymerization of fat, cholesterol, protein and carbohydrates during high-temperature baking, drying, smoking and cooking (frying, deep-frying, roasting, stir-frying, etc.). It is carcinogenic, teratogenic and toxic, posing a serious threat to human health and the environment. It mainly enters the human body through diet and causes damage to many organs of the human body, such as the eyes and breasts. my country's standard GB2762-2017 "National Food Safety Standard Limits of Contaminants in Food" stipulates that the limit of benzo(a)pyrene in vegetable oil is 10μg / kg.

[0003] The methods for reducing and controlling benzo(a)pyrene in food oils and fats mainly include physical adsorption, low temperature sedimentation, solvent extraction, microbial removal, etc. Physical adsorption is considered to be a low-cost and high-efficiency method because of its simple process, high efficiency and non-toxic intermediates. The adsorbents used to adsorb benzo(a)pyrene mainly include activated carbon, carbon nanotubes, graphene oxide and covalent organic frameworks, etc. Some of these adsorbents are not widely used because of their high prices and complex preparation processes. Therefore, it is urgent to develop new and efficient adsorbents to remove benzo(a)pyrene from vegetable oils to meet the limit standards. Summary of the invention

[0004] The main purpose of the present invention is to propose a preparation method of porous activated carbon and its application, aiming to provide a physical adsorbent which can efficiently remove benzo(a)pyrene from vegetable oil and has a simple preparation process and low cost.

[0005] To achieve the above object, the present invention provides a method for preparing porous activated carbon, which comprises the following steps:

[0006] mixing alginic acid and ammonium chloride to obtain mixed granular powder;

[0007] Grinding the mixed particle powder to obtain mixed fine powder;

[0008] The mixed fine powder is heat-treated under a protective gas atmosphere to obtain porous activated carbon.

[0009] Optionally, in the step of mixing alginic acid and ammonium chloride to obtain a mixed granular powder:

[0010] The mass ratio of the alginate to ammonium chloride is 1:0.5-2.

[0011] Optionally, in the step of grinding the mixed particle powder to obtain a mixed fine powder:

[0012] The mixed particles are ground in a ball mill, wherein the rotation speed of the ball mill is set to 800 to 1000 rpm and the grinding time is set to 10 to 40 minutes.

[0013] Optionally, in the step of heat-treating the mixed fine powder under a protective gas atmosphere to prepare porous activated carbon:

[0014] The heating rate of the heat treatment is 4-6°C / min, the heat treatment temperature is 600-1000°C, and the heat treatment time is 2-5h.

[0015] Optionally, in the step of heat-treating the mixed fine powder under a protective gas atmosphere to prepare porous activated carbon:

[0016] The protective gas includes nitrogen.

[0017] Furthermore, the present invention also provides a method for removing benzo(a)pyrene from vegetable oil, the method for removing benzo(a)pyrene from vegetable oil comprising the following steps:

[0018] The porous activated carbon is used to remove benzo(a)pyrene in the vegetable oil to be treated. The porous activated carbon is prepared by the preparation method of the porous activated carbon as described above.

[0019] Optionally, the step of using porous activated carbon to remove benzo(a)pyrene from the vegetable oil to be treated comprises:

[0020] The porous activated carbon is added into the vegetable oil to be treated, stirred at a preset temperature, and then the porous activated carbon is separated to obtain the vegetable oil from which benzo(a)pyrene has been removed.

[0021] Optionally, in the step of adding porous activated carbon to the vegetable oil to be treated, stirring at a preset temperature, and then separating the porous activated carbon therefrom to obtain the vegetable oil from which benzo(a)pyrene has been removed:

[0022] 0.1 to 0.6 g of the porous activated carbon is added to every 100 mL of the vegetable oil to be treated.

[0023] Optionally, in the step of adding porous activated carbon to the vegetable oil to be treated, stirring at a preset temperature, and then separating the porous activated carbon therefrom to obtain the vegetable oil from which benzo(a)pyrene has been removed:

[0024] The preset temperature is 60-120° C., and the stirring time is 10-50 min.

[0025] Optionally, the concentration of benzo(a)pyrene in the vegetable oil to be treated is 2 to 60 ng / mL.

[0026] Optionally, the vegetable oil comprises sunflower oil.

[0027] In the technical solution provided by the present invention, a porous activated carbon material is prepared by mixing, grinding and heat treating alginic acid and ammonium chloride as raw materials. The preparation process is simple and easy, the cost is low, and it is easy to realize industrial mass production. When the porous activated carbon material is used for physical adsorption to remove excess benzo(a)pyrene in vegetable oil, the adsorption performance is excellent, and the removal rate of benzo(a)pyrene reaches more than 90%, so that the benzo(a)pyrene content in the treated vegetable oil can reach the limit standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A schematic flow chart of an embodiment of a method for preparing porous activated carbon provided by the present invention;

[0030] Figure 2 This is a SEM image of the porous activated carbon prepared in Example 2 at a magnification of 5000 times and a scale of 10 μm;

[0031] Figure 3 A macroscopic comparison diagram of the porous activated carbon prepared in Example 2 and the activated carbon provided in Comparative Examples 1-3;

[0032] Figure 4 Fourier infrared spectra of the porous activated carbon prepared in Example 2 and the activated carbon provided in Comparative Example 3;

[0033] Figure 5 Raman spectra of the porous activated carbon prepared in Example 2 and the activated carbon provided in Comparative Example 3.

[0034] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0035] To make the purpose, technical scheme and advantages of the embodiment of the present invention clearer, the technical scheme in the embodiment of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiment, it is carried out according to the normal conditions or the conditions recommended by the manufacturer. If the reagents or instruments used do not specify the manufacturer, they are all conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, taking "A and / or B" as an example, including scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention.

[0036] In order to develop a new type of high-efficiency adsorbent to remove benzo(a)pyrene from vegetable oil to meet the limit standard, the present invention provides a method for preparing porous activated carbon, which uses alginic acid and ammonium chloride as raw materials to prepare porous activated carbon, which has excellent adsorption performance for benzo(a)pyrene in vegetable oil. Specifically, Figure 1 FIG. 1 is an example of a method for preparing porous activated carbon provided by the present invention. Figure 1 As shown, in this embodiment, the method for preparing the porous activated carbon comprises the following steps:

[0037] Step S10, mixing alginic acid and ammonium chloride to obtain mixed particle powder;

[0038] Step S20, grinding the mixed particle powder to obtain mixed fine powder;

[0039] Step S30: heat-treating the mixed fine powder under a protective gas atmosphere to obtain porous activated carbon.

[0040] In the technical solution provided by the present invention, a porous activated carbon material is prepared by mixing, grinding and heat treating alginic acid and ammonium chloride as raw materials. The preparation process is simple and easy, the cost is low, and it is easy to realize industrial mass production. When the porous activated carbon material is used for physical adsorption to remove excess benzo(a)pyrene in vegetable oil, the adsorption performance is excellent, and the removal rate of benzo(a)pyrene reaches more than 90%, so that the benzo(a)pyrene content in the treated vegetable oil can reach the limit standard.

[0041] In some embodiments of the present invention, the mass ratio of alginate and ammonium chloride in step S10 is 1:0.5-2, for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2 and the like.

[0042] It should be noted that the raw materials of alginate and ammonium chloride used in the present invention are usually in powder form. The "fine powder" described in step S20 is relative to the "granular powder" in step S10. After the mixed granular powder is ground, the particle size is reduced and becomes a "finer" powder, so it is referred to as "fine powder" in this article. In some embodiments of the present invention, the method of grinding the mixed particles in step S20 includes grinding with a ball mill. Specifically, the rotation speed of the ball mill is set to 800-1000rpm, for example, it can be 800rpm, 850rpm, 900rpm, 950rpm, 1000rpm, etc., and the grinding time of the ball mill is set to 10-40min, for example, it can be 10min, 15min, 20min, 25min, 30min, 35min, 40min, etc.

[0043] Further, in some embodiments of the present invention, the heating rate of the heat treatment in step S30 is 4 to 6°C / min, for example, it can be 4°C / min, 4.5°C / min, 5°C / min, 5.5°C / min, 6°C / min, etc., and in some specific embodiments of the present invention, it is preferably 5°C / min; the heat treatment temperature of the heat treatment is 600 to 1000°C, for example, it can be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, etc., and the heat treatment time of the heat treatment is 2 to 5h, for example, it can be 2h, 2h 30min, 3h, 3h 30min, 4h, 4h 30min, 5h, etc.

[0044] The main purpose of the protective gas in step S30 is to isolate oxygen and avoid side reactions. Nitrogen, argon, etc. can be selected. Specifically, in some embodiments of the present invention, the protective gas in step S30 includes nitrogen, which has low cost and high safety.

[0045] Based on the preparation method of the porous activated carbon provided by the present invention, the present invention also proposes a method for removing benzo(a)pyrene from vegetable oil, the method for removing benzo(a)pyrene from vegetable oil comprising the following steps: using porous activated carbon to remove benzo(a)pyrene from the vegetable oil to be treated, the porous activated carbon is prepared by the preparation method of the porous activated carbon provided by the above embodiment. When the porous activated carbon prepared by the method provided by the present invention is used to remove excess benzo(a)pyrene from vegetable oil, the adsorption performance is excellent, and the removal rate of benzo(a)pyrene reaches more than 90%, which can make the benzo(a)pyrene content in the treated vegetable oil reach the limit standard, and the adsorption treatment method is simple, non-toxic and pollution-free.

[0046] Specifically, in some embodiments of the present invention, the step of using porous activated carbon to remove benzo(a)pyrene from the vegetable oil to be treated includes: adding the porous activated carbon to the vegetable oil to be treated, stirring at a preset temperature, and then separating the porous activated carbon therefrom to obtain the vegetable oil from which benzo(a)pyrene has been removed.

[0047] Furthermore, in some embodiments of the present invention, the amount of the porous activated carbon added when removing benzo(a)pyrene from vegetable oil is: 0.1 to 0.6 g of the porous activated carbon is added to every 100 mL of the vegetable oil to be treated. For example, the mass of the porous activated carbon added to every 100 mL of the vegetable oil to be treated can be 0.1 g, 0.15 g, 0.2 g, 0.25 g, 0.3 g, 0.35 g, 0.4 g, 0.45 g, 0.5 g, 0.55 g, 0.6 g, and the like.

[0048] In some embodiments of the present invention, the preset temperature when using the porous activated carbon to remove benzo(a)pyrene in vegetable oil is 60-120°C, for example, it can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc., and the stirring time is 10-50min, for example, it can be 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, etc.

[0049] The method for removing benzo(a)pyrene from vegetable oil provided by the present invention can be applied to vegetable oils with different benzo(a)pyrene contents, and has high removal efficiency. Preferably, in some embodiments of the present invention, the concentration of benzo(a)pyrene in the vegetable oil to be treated is 2 to 60 ng / mL. Within this range, the removal efficiency of benzo(a)pyrene in the vegetable oil is higher, which can reach more than 90%, and the content of benzo(a)pyrene in the vegetable oil after adsorption treatment can reach the limit standard.

[0050] The method for removing benzo(a)pyrene from vegetable oil provided by the present invention is suitable for most conventional vegetable oils, such as soybean oil, peanut oil, sunflower oil, camellia oil, etc. In some embodiments of the present invention, preferably, the vegetable oil includes sunflower oil, and the removal efficiency of benzo(a)pyrene in sunflower oil is significant.

[0051] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0052] Example 1

[0053] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:1 to obtain a mixed granular powder.

[0054] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 1000 rpm, and ball milling time of 20 min.

[0055] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 900 °C at a rate of 5 °C / min and kept at this temperature for 3 h to obtain porous activated carbon.

[0056] Example 2

[0057] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:0.5 to obtain mixed granular powder.

[0058] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 1000 rpm, and ball milling time of 20 min.

[0059] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 900 °C at a rate of 5 °C / min and kept at this temperature for 3 h to obtain porous activated carbon.

[0060] Example 3

[0061] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:1.5 to obtain mixed granular powder.

[0062] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 1000 rpm, and ball milling time of 20 min.

[0063] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 900 °C at a rate of 5 °C / min and kept at this temperature for 3 h to obtain porous activated carbon.

[0064] Example 4

[0065] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:2 to obtain mixed granular powder.

[0066] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 1000 rpm, and ball milling time of 20 min.

[0067] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 900 °C at a rate of 5 °C / min and kept at this temperature for 3 h to obtain porous activated carbon.

[0068] Example 5

[0069] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:0.8 to obtain mixed granular powder.

[0070] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 800 rpm, and ball milling time of 40 min.

[0071] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 1000°C at a rate of 4°C / min and kept at this temperature for 2 h to obtain porous activated carbon.

[0072] Example 6

[0073] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:1.2 to obtain mixed granular powder.

[0074] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 850 rpm, and ball milling time of 35 min.

[0075] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 800 °C at a rate of 4.5 °C / min and kept at this temperature for 4 h to obtain porous activated carbon.

[0076] Example 7

[0077] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:1.8 to obtain mixed granular powder.

[0078] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 900 rpm, and ball milling time of 30 min.

[0079] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 700 °C at a rate of 5 °C / min and kept at this temperature for 4.5 h to obtain porous activated carbon.

[0080] Example 8

[0081] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:1 to obtain a mixed granular powder.

[0082] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 950 rpm, and ball milling time of 25 min.

[0083] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 600 °C at a rate of 5.5 °C / min and kept at this temperature for 5 h to obtain porous activated carbon.

[0084] Example 9

[0085] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:0.5 to obtain mixed granular powder.

[0086] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 900 rpm, and ball milling time of 15 min.

[0087] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 750°C at a rate of 6°C / min and kept at this temperature for 3.5 h to obtain porous activated carbon.

[0088] Example 10

[0089] (1) Alginate and ammonium chloride are mixed in a mass ratio of 1:1.5 to obtain mixed granular powder.

[0090] (2) Grinding the mixed particle powder using a ball mill to obtain a mixed fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 1000 rpm, and ball milling time of 10 min.

[0091] (3) Under nitrogen protection, the mixed fine powder was placed in a muffle furnace, heated to 850°C at a rate of 5°C / min and kept at this temperature for 2.5 h to obtain porous activated carbon.

[0092] Embodiment 11

[0093] The porous activated carbon (prepared in Example 1) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 30 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.2 g. The mixture was then placed in a water bath at 80° C. and stirred for 20 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0094] Example 12

[0095] The porous activated carbon (prepared in Example 2) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 30 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.1 g. The mixture was then placed in a water bath at 60° C. and stirred for 50 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0096] Embodiment 13

[0097] The porous activated carbon (prepared in Example 3) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 30 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.3 g. The mixture was then placed in a water bath at 70° C. and stirred for 30 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0098] Embodiment 14

[0099] The porous activated carbon (prepared in Example 4) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 2 ng / mL, and the mass of the porous activated carbon added per 100 mL of the sunflower oil to be treated was 0.4 g. The mixture was then placed in a 90° C. water bath and stirred for 20 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0100] Embodiment 15

[0101] The porous activated carbon (prepared in Example 5) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 10 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.5 g. The mixture was then placed in a water bath at 100° C. and stirred for 25 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0102] Example 16

[0103] The porous activated carbon (prepared in Example 6) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 20 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.6 g. The mixture was then placed in a water bath at 110° C. and stirred for 15 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0104] Embodiment 17

[0105] The porous activated carbon (prepared in Example 7) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 40 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.25 g. The mixture was then placed in a water bath at 120° C. and stirred for 10 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0106] Embodiment 18

[0107] The porous activated carbon (prepared in Example 8) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 60 ng / mL, and the mass of the porous activated carbon added per 100 mL of the sunflower oil to be treated was 0.35 g. The mixture was then placed in a water bath at 85° C. and stirred for 40 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0108] Embodiment 19

[0109] The porous activated carbon (prepared in Example 9) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 50 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.45 g. The mixture was then placed in a water bath at 75° C. and stirred for 45 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0110] Embodiment 20

[0111] The porous activated carbon (prepared in Example 10) was added to the sunflower oil to be treated with a benzo(a)pyrene content of 30 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.55 g. The mixture was then placed in a water bath at 95° C. and stirred for 35 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0112] Comparative Example 1

[0113] (1) Grinding the alginate particle powder using a ball mill to obtain fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 1000 rpm and ball milling time of 20 min.

[0114] (2) Under nitrogen protection, the fine powder was placed in a muffle furnace, heated to 900°C at a rate of 5°C / min and kept at this temperature for 3 h to obtain activated carbon.

[0115] Comparative Example 2

[0116] (1) Grinding the ammonium chloride granular powder using a ball mill to obtain a fine powder; wherein the grinding parameters of the ball mill are set as: ball milling speed of 1000 rpm and ball milling time of 20 min.

[0117] (2) Under nitrogen protection, the fine powder was placed in a muffle furnace, heated to 900°C at a rate of 5°C / min and kept at this temperature for 3 h to obtain activated carbon.

[0118] Comparative Example 3

[0119] Commercially available activated carbon.

[0120] Comparative Example 4

[0121] The activated carbon prepared in Comparative Example 1 was added to the sunflower oil to be treated with a benzo(a)pyrene content of 30 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.2 g. The mixture was then placed in a water bath at 80° C. and stirred for 20 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0122] Comparative Example 5

[0123] The activated carbon prepared in Comparative Example 2 was added to the sunflower oil to be treated with a benzo(a)pyrene content of 30 ng / mL, with the mass of the porous activated carbon added to every 100 mL of the sunflower oil to be treated being 0.2 g. The mixture was then placed in a water bath at 80° C. and stirred for 20 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain the vegetable oil from which benzo(a)pyrene had been removed.

[0124] Comparative Example 6

[0125] Commercially available activated carbon was added to sunflower oil to be treated with a benzo(a)pyrene content of 30 ng / mL, with the mass of porous activated carbon added to every 100 mL of sunflower oil to be treated being 0.2 g. The mixture was then placed in a water bath at 80°C and stirred for 20 min. The mixture was centrifuged and the adsorbent activated carbon was discarded to obtain vegetable oil from which benzo(a)pyrene had been removed.

[0126] Take the products of the embodiments and comparative examples and observe their morphology. Figure 2 and Figure 3 As shown. Among them, Figure 2 The following is a SEM image of the product of the embodiment (taking embodiment 2 as an example), Figure 3 For example (taking Example 2 as an example, Figure 3 A) and comparative example ( Figure 3 B, C, and D are macroscopic comparison diagrams of the products of Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively. Figure 2 and Figure 3 It can be seen that the porous activated carbon prepared in the embodiment has a rough surface with a large number of wrinkles and pores, and the pores are of different sizes and shapes. The sample itself is granular, and the pores belong to the macropore (pore diameter > 50nm) and mesopore (pore diameter in the range of 2 to 50nm), which is conducive to the adsorption of benzo(a)pyrene.

[0127] Take the products of the embodiment (taking embodiment 2 as an example) and the comparative example (taking comparative example 3 as an example) and perform Fourier transform infrared spectroscopy detection. The results are as follows Figure 4 As shown. Figure 4 It can be seen that the peak shapes of the embodiment and the comparative example are similar, but the intensities are different. Compared with the comparative example, the -OH peak intensity of the embodiment is greater, and the porous activated carbon prepared in the embodiment contains rich functional groups, thereby improving the adsorption capacity of pollutants.

[0128] Take the products of the embodiment (taking embodiment 2 as an example) and the comparative example (taking comparative example 3 as an example) and perform Raman spectroscopy detection. The results are as follows Figure 5 As shown. Figure 5 It can be seen that the ID / IG values ​​of both the example and the comparative example samples are less than 1, but the ID / IG value of the example (0.98) is greater than the ID / IG of the comparative example (0.85), which indicates that the example sample has a higher degree of graphitization, fewer structural defects, and is mainly composed of functional groups composed of amorphous carbon.

[0129] 0.4 g of sunflower oil from which benzo(a)pyrene has been removed in Examples 11-20 and Comparative Examples 1-3 was taken respectively, and n-hexane was added, and the mixture was passed through a benzo(a)pyrene molecular imprinting column activated with dichloromethane and n-hexane, and the purified liquid was collected by elution with 6 mL of dichloromethane. The purified liquid was dried with nitrogen at 40° C., fixed to 1 mL with acetonitrile, and measured by liquid chromatography after passing through a microporous filter membrane. The adsorption rate was calculated using the test results, and the calculation results are shown in Table 1 below.

[0130] Table 1 Removal rate and residual amount of benzo(a)pyrene in the examples and comparative examples

[0131] Removal rate (%) Residue(μg / kg) Embodiment 11 92.2±0.25 5.8±0.32 Example 12 96.7±0.36 2.4±0.17 Embodiment 13 93.6±0.68 4.7±0.45 Embodiment 14 100.0±0.00 0±0.00 Embodiment 15 98.7±0.11 0.3±0.17 Example 16 97.8±0.29 1.1±0.24 Embodiment 17 95.6±0.36 4.4±0.30 Embodiment 18 92.4±0.27 11.4±0.35 Embodiment 19 93.7±0.28 7.8±0.17 Embodiment 20 96.6±0.20 2.55±0.29 Comparative Example 4 79.3±0.47 15.5±0.29 Comparative Example 5 56.5±0.53 32.6±0.44 Comparative Example 6 87.2±0.28 9.6±0.22

[0132] It can be seen from the results in Table 1 that the removal rates of benzo(a)pyrene in sunflower oil in the embodiments are all above 90%, and the residual amounts of benzo(a)pyrene in sunflower oil are all less than 10 μg / kg, which are in line with national standards. In the comparative examples, although the residual amount of benzo(a)pyrene in sunflower oil in comparative example 3 is less than 10 μg / kg, its adsorption rate is significantly lower than that in the embodiments, and the residual amount of benzo(a)pyrene is also higher.

[0133] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A method for preparing porous activated carbon, characterized in that: The preparation method of the porous activated carbon comprises the following steps: mixing alginic acid and ammonium chloride to obtain mixed granular powder; Grinding the mixed particle powder to obtain mixed fine powder; The mixed fine powder is heat-treated under a protective gas atmosphere to obtain porous activated carbon.

2. The method for preparing porous activated carbon according to claim 1, characterized in that: In the step of mixing alginic acid and ammonium chloride to obtain a mixed granular powder: The mass ratio of the alginate to ammonium chloride is 1:0.5-2.

3. The method for preparing porous activated carbon according to claim 1, characterized in that: In the step of grinding the mixed particle powder to obtain a mixed fine powder: The mixed particles are ground in a ball mill, wherein the rotation speed of the ball mill is set to 800 to 1000 rpm and the grinding time is set to 10 to 40 minutes.

4. The method for preparing porous activated carbon according to claim 1, characterized in that: In the step of heat treating the mixed fine powder under a protective gas atmosphere to prepare porous activated carbon: The heating rate of the heat treatment is 4-6°C / min, the heat treatment temperature is 600-1000°C, and the heat treatment time is 2-5h.

5. The method for preparing porous activated carbon according to claim 1, characterized in that: In the step of heat treating the mixed fine powder under a protective gas atmosphere to prepare porous activated carbon: The protective gas includes nitrogen.

6. A method for removing benzo(a)pyrene from vegetable oil, characterized in that: The method for removing benzo(a)pyrene from vegetable oil comprises the following steps: Porous activated carbon is used to remove benzo(a)pyrene in the vegetable oil to be treated, and the porous activated carbon is prepared by the preparation method of the porous activated carbon as described in any one of claims 1 to 5.

7. The method for removing benzo(a)pyrene from vegetable oil according to claim 6, characterized in that: The step of using porous activated carbon to remove benzo(a)pyrene from the vegetable oil to be treated comprises: The porous activated carbon is added into the vegetable oil to be treated, stirred at a preset temperature, and then the porous activated carbon is separated to obtain the vegetable oil from which benzo(a)pyrene has been removed.

8. The method for removing benzo(a)pyrene from vegetable oil according to claim 7, characterized in that: The porous activated carbon is added to the vegetable oil to be treated, stirred at a preset temperature, and then the porous activated carbon is separated to obtain the vegetable oil from which benzo(a)pyrene has been removed: 0.1 to 0.6 g of the porous activated carbon is added to every 100 mL of the vegetable oil to be treated.

9. The method for removing benzo(a)pyrene from vegetable oil according to claim 7, characterized in that: The porous activated carbon is added to the vegetable oil to be treated, stirred at a preset temperature, and then the porous activated carbon is separated to obtain the vegetable oil from which benzo(a)pyrene has been removed: The preset temperature is 60-120° C., and the stirring time is 10-50 min.

10. The method for removing benzo(a)pyrene from vegetable oil according to claim 6, characterized in that: The concentration of benzo(a)pyrene in the vegetable oil to be treated is 2-60 ng / mL.

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