Bentonite / graphite composite mycotoxin adsorbent as well as preparation method and application thereof

Abstract

The invention provides a bentonite / graphite composite mycotoxin adsorbent as well as a preparation method and application thereof, and the method comprises the following steps: uniformly mixing calcium bentonite powder, transition type bentonite powder, sodium bentonite powder, sodium modified bentonite powder and graphite powder to obtain a powdery bentonite / graphite composite mycotoxin adsorbent; the preparation method also comprises the following steps: uniformly mixing the powdery bentonite / graphite composite mycotoxin adsorbent and a binder in proportion, granulating, and drying to obtain the granular bentonite / graphite composite mycotoxin adsorbent. The prepared composite mycotoxin adsorbent can be used for adsorbing and removing mycotoxin in the feed industry, has efficient adsorption performance on aflatoxin B1 and zearalenone at the same time, is simple in process, low in production cost and easy to produce on a large scale, and has high economic benefits and social benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of mycotoxin removal from feed and feedstuff, and in particular to the preparation and application of composite mycotoxin adsorbing materials. Specifically, it relates to a bentonite / graphite composite mycotoxin adsorbent, a preparation method thereof, and the application of the composite mycotoxin adsorbent in adsorbing aflatoxin B1, zearalenone and other mycotoxins. Background Art

[0002] Aflatoxin B1 and zearalenone are common and highly toxic mycotoxins in nature, often found in food crops and animal feed. Aflatoxin B1 is mutagenic and can cause chromosome aberrations and chromosome breaks. Its lethal dose is very low. When eating food containing excessive amounts of aflatoxin B1, it will cause acute poisoning. Long-term intake will cause chronic poisoning through cumulative effects, leading to the occurrence of liver cancer, etc. Zearalenone is extremely harmful to both humans and animals. After entering the body of animals with feed, it will cause immunosuppression and change the relative mass of organs, making animals susceptible to diseases and increasing mortality. When vomitoxin is consumed by humans and animals, it will irritate the gastrointestinal tract, causing symptoms such as nausea, vomiting, and diarrhea.

[0003] Bentonite has a large specific surface area, high cation exchange capacity, strong hydrophilicity, and good adsorption performance. It is often used to adsorb heavy metals in soil and toxic and harmful substances in water. Graphite has the characteristics of large specific surface area and developed pore structure. It shows good adsorption performance for a variety of organic pollutants. In theory, it can be used as an efficient mycotoxin adsorption material.

[0004] Bentonite / graphite composite mycotoxin adsorbent can make up for the problems of low efficiency and single type of mycotoxins adsorbed by single adsorbent.

[0005] Therefore, the compound of bentonite and graphite as a mycotoxin adsorbent can have more efficient adsorption performance and can be used as a composite mycotoxin adsorbent in industries such as animal husbandry. Summary of the invention

[0006] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the purposes of the present invention is to provide a powdered bentonite / graphite composite mycotoxin adsorbent with a simple preparation process; the second purpose of the present invention is to provide a granular bentonite / graphite composite mycotoxin adsorbent with a simple preparation process; the third purpose of the present invention is to provide the application of the bentonite / graphite composite mycotoxin adsorbent in feed.

[0007] In order to achieve the above-mentioned object, the present invention provides a method for preparing a bentonite / graphite composite mycotoxin adsorbent. The bentonite / graphite composite mycotoxin adsorbent is in powder form.

[0008] The method may include the following steps: mixing 1 part of calcium-based bentonite powder, 0-2 parts of transitional bentonite powder, 0-2.5 parts of sodium-based bentonite powder, 0-2.5 parts of sodium-bentonite powder and 0.2-1.5 parts of graphite powder evenly by mass to obtain a powdered bentonite / graphite composite mycotoxin adsorbent.

[0009] Optionally, the main mineral component of the calcium-based bentonite, sodium-based bentonite and transitional bentonite is montmorillonite, the percentage of montmorillonite in the calcium-based bentonite powder, transitional bentonite powder, sodium-based bentonite powder and sodium bentonite is ≥60%, and the powder particle size is ≤0.74μm.

[0010] Optionally, the graphite powder may include microcrystalline graphite powder and / or tail powder from the processing of flake graphite, with a purity of ≥60% and a powder particle size of ≤0.74 μm.

[0011] Alternatively, the sodium bentonite powder can be obtained by sodium treatment of calcium-based bentonite and / or transitional bentonite;

[0012] The sodium treatment may include mixing calcium-based bentonite powder and / or transitional bentonite powder, water and a sodium agent to perform a sodium reaction, and obtaining sodium bentonite powder after drying and grinding;

[0013] Wherein, the sodiumizing agent may include one or more of sodium carbonate, sodium bicarbonate, sodium silicate, sodium phosphate and sodium hydroxide.

[0014] Another aspect of the present invention provides a powdery bentonite / graphite composite mycotoxin adsorbent.

[0015] The adsorbent can be prepared by the above method.

[0016] The adsorption rates of the adsorbent on aflatoxin B1, zearalenone and vomitoxin are 85-99%, 80-99% and 26-40% respectively.

[0017] In another aspect, the present invention provides a method for preparing a bentonite / graphite composite mycotoxin adsorbent. The bentonite / graphite composite mycotoxin adsorbent is in a granular form.

[0018] The method may include the following steps:

[0019] The powdery bentonite / graphite composite mycotoxin adsorbent and the binder are uniformly mixed, granulated, and dried to obtain a granular bentonite / graphite composite mycotoxin adsorbent.

[0020] Optionally, the binder includes water, or includes water and starch, wherein the water includes drinking water, and the starch includes one or more of corn starch, sweet potato starch, potato starch and wheat starch.

[0021] The mass ratio of the powdered bentonite / graphite composite mycotoxin adsorbent to the water and the starch may be 1:(0.2-0.6):(0-0.06).

[0022] Optionally, the granulation method may include: extrusion granulation by an extruder (press), round pot rotary granulation or disc rotary granulation; the shape of the granules includes cylindrical and / or spherical, wherein the diameter of the cylindrical granules is 0.5 to 2 mm and the length is 0.5 to 2 mm; the diameter of the spherical granules is 0.5 to 2 mm.

[0023] Optionally, the drying treatment includes natural airing or drying in a drying device not exceeding 200° C., wherein the drying device includes a rotary kiln dryer and a fluidized bed dryer. After drying, the moisture content of the granular bentonite / graphite composite mycotoxin adsorbent is 10-15%.

[0024] Another aspect of the present invention provides a granular bentonite / graphite composite mycotoxin adsorbent, which is prepared by the method in the above-mentioned another aspect.

[0025] The adsorption rates of the adsorbent on aflatoxin B1, zearalenone and vomitoxin are 85-99%, 80-99% and 26-40% respectively.

[0026] The present invention further provides the use of bentonite / graphite composite mycotoxin adsorbent in feed, wherein the adsorbent is one or more of the powdered or granular bentonite / graphite composite mycotoxin adsorbents prepared by the above method.

[0027] Optionally, the bentonite / graphite composite mycotoxin adsorbent is used in feed at a mass ratio of the adsorbent to the feed of 1:(300-600) to adsorb the mycotoxins in the contaminated feed.

[0028] Alternatively, the use of the powdered and granular bentonite / graphite composite mycotoxin adsorbent in feed may include the following steps:

[0029] The application steps for powdered bentonite / graphite composite mycotoxin adsorbent are:

[0030] The powdered bentonite / graphite composite mycotoxin adsorbent and feed are weighed according to a ratio, and the weighed adsorbent and feed are mixed evenly.

[0031] The application steps for the granular bentonite / graphite composite mycotoxin adsorbent are:

[0032] The granular bentonite / graphite composite mycotoxin adsorbent is weighed according to a ratio, placed in a disperser and broken into powder, and then the feed weighed according to the ratio is placed in the disperser and mixed evenly with the broken powder; the granular composite mycotoxin adsorbent has the characteristic of not raising dust during packaging, transportation and use.

[0033] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0034] (1) The raw and auxiliary materials used in the production of the present invention are low in price, widely available, and have excellent performance, thus having good economic and social benefits.

[0035] (2) The composite mycotoxin adsorbent prepared by using bentonite and graphite can simultaneously adsorb multiple mycotoxins such as aflatoxin, zearalenone, ochratoxin, fumonisin, etc., and has a good adsorption effect, and can also be used to protect the gastrointestinal mucosa of livestock and poultry.

[0036] (3) The preparation method of the powdered adsorbent prepared by the present invention has simple process, low production cost, abundant raw materials, is easy to mass produce, and has relatively good adsorption properties for different mycotoxins.

[0037] (4) The granular adsorbent prepared by the present invention has a simple preparation process, good adsorption effect, is easy to transport, and is not prone to generating dust during packaging and transportation.

[0038] (5) The adsorbent of the present invention can achieve an adsorption rate of up to 99% for aflatoxin B1 and zearalenone. At the same time, it also has a certain adsorption effect on vomitoxin, etc., with an adsorption rate of up to 40%. DETAILED DESCRIPTION

[0039] Hereinafter, the bentonite / graphite composite mycotoxin adsorbent of the present invention and its preparation method and application will be described in detail in conjunction with exemplary embodiments.

[0040] Exemplary Embodiment 1

[0041] This exemplary embodiment provides a method for preparing a powdered bentonite / graphite composite mycotoxin adsorbent, the method comprising the following steps:

[0042] By weight, 1 part of calcium-based bentonite powder, 0-2 parts of transitional bentonite powder, 0-2.5 parts of sodium-based bentonite powder, 0-2.5 parts of sodium-bentonite powder and 0.2-1.5 parts of graphite powder are uniformly mixed to obtain a powdered bentonite / graphite composite mycotoxin adsorbent.

[0043] In this embodiment, the main mineral component of the calcium-based bentonite, sodium-based bentonite and transitional bentonite is montmorillonite, and the percentage of montmorillonite in the calcium-based bentonite, transitional bentonite, sodium-based bentonite and sodium bentonite powder is ≥60%, such as 60%, 65%, 80% or 90%, etc.; the particle size is ≤0.74μm, such as 0.74μm, 0.65μm, 0.60μm, 0.50μm or 0.40μm, etc.

[0044] The purpose of selecting the percentage content of montmorillonite in the above-mentioned different types of bentonite is because montmorillonite is the main phase in bentonite powder that undergoes adsorption. In addition to its adsorption effect on mycotoxins, montmorillonite also has a protective effect on the gastrointestinal mucosa of animals. Therefore, a montmorillonite content of ≥60% can ensure both the adsorption effect on mycotoxins and the protection of the gastrointestinal tract of animals.

[0045] The reason for selecting bentonite particle size range of ≤0.74 μm is that bentonite mineral powder with finer particle size has a larger specific surface area, which can provide more adsorption sites for adsorbing mycotoxins, and also facilitates subsequent mixing and granulation.

[0046] In this embodiment, the graphite powder is the tail powder in the processing of microcrystalline graphite powder and / or flake graphite, with a purity ≥60%, such as 65%, 70%, 80% or 88%, etc.; the particle size is ≤0.74μm, for example, 0.74μm, 0.70μm, 0.65μm, 0.50μm or 0.45μm, etc.

[0047] The advantage of choosing graphite powder is that graphite is hydrophobic and has a good adsorption effect on weakly polar mycotoxins such as zearalenone.

[0048] The advantage of selecting a graphite powder particle size range of ≤0.74μm is that the smaller the particle size, the larger the specific surface area, which can provide more adsorption sites for mycotoxin adsorption and facilitate subsequent mixing and granulation.

[0049] In this embodiment, the sodium bentonite powder can be obtained by sodium treatment of calcium-based bentonite and / or transitional bentonite;

[0050] The sodium treatment is to mix calcium-based bentonite powder and / or transitional bentonite powder, water and a sodium agent to carry out a sodium reaction, and then dry and grind to obtain sodium bentonite;

[0051] Wherein, the sodiumizing agent includes one or more of sodium carbonate, sodium bicarbonate, sodium silicate, sodium phosphate and sodium hydroxide.

[0052] The benefit of sodium modification of calcium-based bentonite and transitional bentonite is that the sodium-modified bentonite has better dispersibility and better adsorption performance for weakly polar mycotoxins.

[0053] Exemplary Embodiment 2

[0054] This exemplary embodiment provides a powdered bentonite / graphite composite mycotoxin adsorbent, which is prepared by the method in exemplary embodiment 1.

[0055] The adsorbent has an adsorption rate of 85-99% for aflatoxin B1, such as 85%, 86.5%, 88.5%, 95% or 99%; an adsorption rate of 80-99% for zearalenone, such as 80%, 82.5%, 85%, 96% or 99%; and an adsorption rate of 26-40% for vomitoxin, such as 26.2%, 27%, 29.5%, 30%, 35%, 40%.

[0056] Exemplary Embodiment 3

[0057] This exemplary embodiment provides a method for preparing a granular bentonite / graphite composite mycotoxin adsorbent, the method comprising the following steps:

[0058] The powdery bentonite / graphite composite mycotoxin adsorbent is evenly mixed with a binder, granulated, and dried to obtain a granular bentonite / graphite composite mycotoxin adsorbent.

[0059] In this embodiment, the binder includes water, or includes water and starch, wherein the water includes drinking water, and the starch includes one or more of corn starch, sweet potato starch, potato starch and wheat starch.

[0060] The mass ratio of the powdered bentonite / graphite composite mycotoxin adsorbent to the water and the starch is 1:A:B, wherein A=0.2-0.6, such as 0.2, 0.25, 0.28, 0.5, 0.59, etc.; B=0-0.06, such as 0, 0.01, 0.02, 0.03, 0.06, etc.

[0061] Among them, the amount of binder added is one of the important factors affecting the structure and performance of bentonite / graphite particles. If the amount of binder is too little, the bentonite / graphite particles are not firmly bonded, or it is difficult to disperse evenly, resulting in granulation failure, unable to produce normally or producing inferior particles; if the amount is too much, the produced bentonite / graphite particles are easily surrounded and blocked by the binder, reducing the content of montmorillonite or graphite in the adsorbent, thereby reducing the adsorption efficiency of bentonite / graphite particles on mycotoxins.

[0062] In this embodiment, the granulation method includes: extrusion granulation by an extruder, a round pot rotary granulation method or a disc rotary granulation method, and the shape of the bentonite particles includes cylindrical and / or spherical, wherein the diameter of the cylindrical particles is 0.5 to 2 mm, for example, 0.5 mm, 0.7 mm, 1.5 mm or 2.0 mm, etc.; the length is 0.5 to 2 mm, for example, 0.5 mm, 0.8 mm, 1.0 mm or 1.5 mm, etc.; the diameter of the spherical particles is 0.5 to 2 mm, for example, 0.5 mm, 0.6 mm, 1.5 mm or 1.8 mm, etc.

[0063] By controlling the shape and size of the particles within the above requirements, it is possible to ensure that the adsorbent is in full contact with the mycotoxins and achieve a better adsorption effect.

[0064] In this embodiment, the drying treatment includes natural drying or drying at a temperature not exceeding 200°C, such as 80°C, 105°C, 110°C or 200°C, etc.; the drying equipment includes a rotary kiln dryer, a fluidized bed dryer, and the moisture content of the bentonite / graphite composite mycotoxin adsorbent after drying is 10-15%, such as 10%, 12%, 13%, 14% or 15%, etc.

[0065] Choosing the natural drying method can save costs, and using drying equipment with a temperature not exceeding 200°C can save time and improve efficiency. The purpose of selecting the above moisture content is to reduce the moisture content of the bentonite / graphite composite mycotoxin adsorbent, avoid adhesion between particles, and facilitate uniform dispersion during use.

[0066] Example 4

[0067] This exemplary embodiment provides a granular bentonite / graphite composite mycotoxin adsorbent, which is prepared by the method described in exemplary embodiment 3.

[0068] The adsorbent has an adsorption rate of 85-99% for aflatoxin B1, such as 86%, 87%, 90%, 93% or 99%; an adsorption rate of 80-99% for zearalenone, such as 82%, 85%, 86%, 92% or 99%; and an adsorption rate of 26-40% for vomitoxin, such as 26.21%, 27.3%, 30.1%, 32.5%, 35%, 40% and the like.

[0069] Exemplary Embodiment 5

[0070] This exemplary embodiment provides the use of a bentonite / graphite composite mycotoxin adsorbent in feed, including use as an additive for feed contaminated with mycotoxins to adsorb mycotoxins in the contaminated feed.

[0071] The adsorbent may be the adsorbent described in Exemplary Embodiment 2 and / or Exemplary Embodiment 4, and the adsorbent is added to the feed at a ratio of 1:(300-600). For example, the ratio of the adsorbent to the feed includes 1:300, 1:320, 1:450, 1:500 or 1:600, etc. Within the above-mentioned additive dosage range, the adsorption rate can be guaranteed without causing excess adsorbent, thereby achieving maximum utilization.

[0072] In this embodiment, the use of the powdered and granular bentonite / graphite composite mycotoxin adsorbent in feed comprises the following steps:

[0073] The application steps for powdered bentonite / graphite composite mycotoxin adsorbent are:

[0074] The powdered bentonite / graphite composite mycotoxin adsorbent and feed are weighed according to a ratio, and the weighed adsorbent and feed are mixed evenly.

[0075] The application steps for the granular bentonite / graphite composite mycotoxin adsorbent are:

[0076] The granular bentonite / graphite composite mycotoxin adsorbent is weighed according to a ratio, placed in a disperser to be broken into powder, and the weighed feed is placed in a disperser according to the ratio and mixed evenly with the broken powder; or the weighed granular bentonite / graphite composite mycotoxin adsorbent and the weighed feed are placed in a stirring disperser and mixed evenly.

[0077] In order to better understand the above exemplary embodiments of the present invention, they are further described below with reference to specific examples.

[0078] Example 1

[0079] The obtained calcium-based bentonite, transitional bentonite and sodium-based bentonite ores are crushed and ground with a powder grinder to remove impurities such as quartz, and then ground through a 200-mesh sieve to obtain three types of bentonite powders, numbered Mt-1, Mt-2, and Mt-3; the obtained calcium-based bentonite and transitional bentonite powders are subjected to sodium treatment to obtain sodium-treated bentonite powders.

[0080] Example 2

[0081] The calcium-based bentonite, transitional bentonite, sodium-based bentonite and sodium-bentonite obtained in Example 1 were uniformly mixed with graphite powder in a mass ratio of 1:0.2:0.2:0.2:0.2 to obtain powdered bentonite / graphite composite mycotoxin adsorbents numbered GMt-4, GMt-5 and GMt-6, with a moisture content of 12%.

[0082] Example 3

[0083] The calcium-based bentonite, transitional bentonite, sodium-based bentonite and sodium-bentonite obtained in Example 1 were uniformly mixed with graphite powder in a mass ratio of 1:0:0.2:0.4:0.4 to obtain powdered bentonite / graphite composite mycotoxin adsorbents numbered GMt-7, GMt-8 and GMt-9, with a moisture content of 15%.

[0084] Example 4

[0085] The powdered bentonite / graphite composite mycotoxin adsorbent obtained in Example 2 was evenly mixed with the drinking water and the starch in a mass percentage of 1:0.2:0, and granulated by a disc rotating granulation method. The granulated shape was a spherical shape with a diameter of 0.8 mm to obtain bentonite / graphite particles.

[0086] The obtained bentonite / graphite particles were dried in an oven at 110° C. to obtain granular bentonite / graphite composite mycotoxin adsorbents numbered GMt-10, GMt-11, and GMt-12, with a moisture content of 10%.

[0087] Example 5

[0088] The powdered bentonite / graphite composite mycotoxin adsorbent obtained in Example 3 was evenly mixed with the drinking water and the starch in a mass percentage of 1:0.4:0.02, and granulated by a disc rotating granulation method. The granulated shape was a spherical shape with a diameter of 1.0 mm to obtain bentonite / graphite particles.

[0089] The obtained bentonite / graphite particles were dried in an oven at 200° C. to obtain granular bentonite / graphite composite mycotoxin adsorbents numbered GMt-13, GMt-14, and GMt-15, with a moisture content of 13%.

[0090] Experimental example

[0091] The mycotoxin adsorbents obtained in the above examples 1-5 were subjected to adsorption tests.

[0092] Aflatoxin B1 (AFB1) adsorption experiment: Add 5 mL of aflatoxin B1 with a concentration of 4 mg / L prepared with phosphate buffer at pH 3.5 into a centrifuge tube, add 10 mg of the bentonite / graphite composite mycotoxin adsorbent obtained in the above example, and adsorb at a constant temperature of 37°C for 2 hours.

[0093] Zearalenone (ZEN) adsorption experiment: Add 5 mL of 4 mg / L zearalenone prepared with pH 3.5 phosphate buffer into a centrifuge tube, add 10 mg of the bentonite / graphite composite mycotoxin adsorbent obtained in the above example, and adsorb at 37°C for 2 h.

[0094] Deoxynivalenol (DON) adsorption experiment: Add 5 mL of 2 mg / L DON prepared with phosphate buffer at pH 3.5 into a centrifuge tube, add 10 mg of the bentonite / graphite composite mycotoxin adsorbent obtained in the above example, and adsorb at 37°C for 2 h.

[0095] The supernatant was taken, filtered through a 0.22 μm filter membrane, and detected by high performance liquid chromatography (HPLC). The adsorption rate was calculated according to the following formula:

[0096] Q=(C0-C t ) / C0×100%

[0097] Where Q is the adsorption rate, %; C0 and C t are the concentrations of mycotoxins before and after adsorption, mg / L, respectively. The adsorption results are shown in Table 1 below.

[0098] From the data in the table, it can be seen that the adsorption rate of aflatoxin B1 and zearalenone by bentonite / graphite composite mycotoxin adsorbent is significantly improved compared with the original bentonite. The adsorption rates of aflatoxin B1, zearalenone and vomitoxin are in the range of 85-99%, 80-99% and 26-40%, respectively.

[0099] Table 1 Adsorption rate of mycotoxins by adsorbents

[0100]

[0101] Although the present invention has been described above in conjunction with exemplary embodiments, it will be apparent to those skilled in the art that various modifications may be made to the above-described embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing a bentonite / graphite composite mycotoxin adsorbent, characterized in that: The preparation method comprises the following steps: By weight, 1 part of calcium-based bentonite powder, 0-2 parts of transitional bentonite powder, 0-2.5 parts of sodium-based bentonite powder, 0-2.5 parts of sodium-bentonite powder and 0.2-1.5 parts of graphite powder are uniformly mixed to obtain a powdered bentonite / graphite composite mycotoxin adsorbent.

2. The method for preparing the bentonite / graphite composite mycotoxin adsorbent according to claim 1, characterized in that: The method further comprises the steps of: uniformly mixing the powdered bentonite / graphite composite mycotoxin adsorbent with a binder, granulating, and drying to obtain a granular bentonite / graphite composite mycotoxin adsorbent.

3. The method for preparing the bentonite / graphite composite mycotoxin adsorbent according to claim 1, characterized in that: The sodium bentonite powder is obtained by sodium treatment of calcium-based bentonite and / or transitional bentonite; The sodium treatment comprises: mixing calcium-based bentonite powder and / or transitional bentonite powder, water and a sodium agent to carry out a sodium reaction, and obtaining sodium bentonite powder after drying and grinding; Wherein, the sodiumizing agent includes one or more of sodium carbonate, sodium bicarbonate, sodium silicate, sodium phosphate and sodium hydroxide.

4. The method for preparing the bentonite / graphite composite mycotoxin adsorbent according to claim 1, characterized in that: The mass percentage of montmorillonite in the calcium-based bentonite powder, transitional bentonite powder, sodium-based bentonite powder and sodium-bentonite powder is ≥60%, and the particle size of the powder is ≤0.74 μm.

5. The method for preparing the bentonite / graphite composite mycotoxin adsorbent according to claim 1, characterized in that: The graphite powder includes microcrystalline graphite powder and / or tail powder in the process of flake graphite processing, with a purity of ≥60% and a powder particle size of ≤0.74 μm.

6. The method for preparing the granular bentonite / graphite composite mycotoxin adsorbent according to claim 2, characterized in that: The binder includes water, or includes water and starch, wherein the starch includes one or more of corn starch, sweet potato starch, potato starch and wheat starch; The mass ratio of the powdered bentonite / graphite composite mycotoxin adsorbent to the water and the starch is 1:(0.2-0.6):(0-0.06).

7. The method for preparing the granular bentonite / graphite composite mycotoxin adsorbent according to claim 2, characterized in that: The shape of the granular bentonite / graphite composite mycotoxin adsorbent includes cylindrical and / or spherical shapes, wherein the diameter of the cylindrical granules is 0.5-2 mm and the length is 0.5-2 mm; the diameter of the spherical granules is 0.5-2 mm.

8. The method for preparing the granular bentonite / graphite composite mycotoxin adsorbent according to claim 2, characterized in that: The drying treatment includes natural drying or drying at a temperature not exceeding 200° C. After drying, the moisture content of the granular bentonite / graphite composite mycotoxin adsorbent is 10-15%.

9. A bentonite / graphite composite mycotoxin adsorbent, characterized in that: The adsorbent is obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the bentonite / graphite composite mycotoxin adsorbent according to claim 9 in feed, wherein the mass ratio of the bentonite / graphite composite mycotoxin adsorbent to feed is 1:(300-600).

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