Chitosan composite material and compound feed additive

Abstract

The invention provides a chitosan composite material and a compound feed additive, and relates to the technical field of feed additives. The chitosan composite material comprises cross-linked chitosan and a porous carrier, the cross-linked chitosan is coated on the surface of the porous carrier; the porous carrier comprises a first porous carrier and a second porous carrier, the average particle size of the first porous carrier is 80-150 [mu] m, and the average particle size of the second porous carrier is 10-30 [mu] m. The chitosan composite material disclosed by the invention has relatively good heavy metal ion adsorption performance and can be used as a feed additive.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of feed additives, and relates to a chitosan composite material and a composite feed additive. BACKGROUND

[0002] Chitosan has a wide range of applications, such as being used as a natural, non-toxic, biodegradable green feed additive to achieve multiple physiological functions in livestock and aquaculture, including promoting growth, regulating immunity, improving intestinal health, reducing cholesterol, and absorbing heavy metal ions. In order to improve the adsorption performance of chitosan on heavy metal ions, one method is to coat chitosan on the surface of a porous carrier (such as zeolite) to form a composite material. This method relies on the electrostatic adsorption between chitosan and the porous carrier, but when passing through the acidic environment of gastric acid, chitosan will partially or completely dissolve and fall off, resulting in a decrease in the adsorption capacity of heavy metal ions. An improved method is to cross-link chitosan using a cross-linking agent, but this will cause the pores of the porous carrier to be blocked, reducing the adsorption performance of the composite material.

[0003] Therefore, the above-mentioned technology needs to be improved to better exert the adsorption performance of chitosan / porous carrier on heavy metal ions. SUMMARY

[0004] In order to solve the above-mentioned technical problems, the present application provides a chitosan composite material and a composite feed additive.

[0005] The technical scheme of the present application is as follows:

[0006] A chitosan composite material, comprising cross-linked chitosan and a porous carrier;

[0007] The cross-linked chitosan is coated on the surface of the porous carrier;

[0008] The porous carrier comprises a first porous carrier and a second porous carrier;

[0009] The average particle size of the first porous carrier is 80-150 μm, and the average particle size of the second porous carrier is 10-30 μm.

[0010] Preferably, the first porous carrier and the second porous carrier are independently selected from one or a combination of two or more of zeolite, porous ceramic, mesoporous silica, activated carbon, and expanded perlite.

[0011] Preferably, the weight ratio of the first porous carrier to the second porous carrier is 1:2-3:1.

[0012] Preferably, the preparation method of the chitosan composite material is as follows:

[0013] The chitosan is added into an acidic aqueous solution and dissolved to obtain a chitosan aqueous solution;

[0014] The porous carrier is dispersed into the chitosan aqueous solution, stirred for 1-24 h, and the solid is separated to obtain a pre-coated carrier;

[0015] The pre-coated carrier is reacted with a cross-linking agent to obtain the chitosan composite material.

[0016] More preferably, the degree of deacetylation of the chitosan is not less than 85%, and the concentration of the chitosan aqueous solution is 0.5-5 wt%.

[0017] More preferably, the weight ratio of the chitosan to the porous carrier is 1:1-1:20.

[0018] More preferably, the porous carrier is pretreated.

[0019] The pretreatment comprises, in sequence, pickling, neutralization and calcination activation.

[0020] More preferably, the cross-linking agent is selected from one or a combination of two or more of glutaraldehyde, epichlorohydrin and polyisocyanate compound.

[0021] Further preferably, the cross-linking agent is selected from a polyisocyanate compound with a number average molecular weight of 300-2300.

[0022] A composite feed additive comprises the chitosan composite material according to any one of the above embodiments.

[0023] The present application has the following advantages:

[0024] (1) The present application uses the combination of two porous carriers with different particle sizes to avoid the problem of poor adsorption performance caused by cross-linking of chitosan, so that the chitosan composite material maintains good stability and good adsorption performance.

[0025] (2) The use of a polyisocyanate compound with a relatively large molecular weight as a cross-linking agent avoids or reduces the problem of pore blockage of the porous carrier caused by excessive cross-linking of the cross-linked chitosan, and the chitosan composite material maintains good adsorption performance.

[0026] (3) The chitosan composite material of the present application is difficult to be dissolved or absorbed in the stomach acid environment and the intestinal environment due to the cross-linked form of chitosan, and the chitosan composite material can be completely excreted after adsorbing heavy metal ions in the organism and / or feed, thereby avoiding the absorption and accumulation of heavy metal ions by the organism. DETAILED DESCRIPTION

[0027] The technical solutions of the present application are further described and explained in the following specific embodiments.

[0028] In one aspect, the present application provides a chitosan composite material, comprising cross-linked chitosan and a porous carrier;

[0029] The cross-linked chitosan is coated on the surface of the porous carrier;

[0030] The porous carrier comprises a first porous carrier and a second porous carrier;

[0031] The average particle size of the first porous carrier is 80-150 μm, and the average particle size of the second porous carrier is 10-30 μm.

[0032] The present application uses cross-linked chitosan to coat the porous carrier composed of the first porous carrier and the second porous carrier, which can avoid the blockage of the porous carrier by the cross-linked chitosan and thus affect the adsorption performance. The particle sizes of the first porous carrier and the second porous carrier are different, which can form a good gradation, and even after being coated with cross-linked chitosan, still have good adsorption performance.

[0033] For the average particle size of the first porous carrier, for example, it can be any value or any value between 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, etc. For the average particle size of the second porous carrier, for example, it can be any value or any value between 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 23 μm, 25 μm, 30 μm, etc. For the first porous carrier and the second porous carrier, there is no particular limitation on the pore size, which is generally nanoscale or close to micrometer scale, such as 5 nm-1 μm.

[0034] In some embodiments, the first porous carrier and the second porous carrier are independently selected from one or a combination of two or more of zeolite, porous ceramic, mesoporous silica, activated carbon and expanded perlite. From the comprehensive consideration of cost and performance, the first porous carrier and the second porous carrier can be zeolite respectively, which can be natural zeolite or artificial zeolite.

[0035] In some embodiments, the weight ratio of the first porous carrier and the second porous carrier is 1:2-3:1, for example, the weight ratio can be any value or any value between 1:2, 2:3, 1:1, 3:2, 2:1, 3:1, etc.

[0036] In some embodiments, the preparation method of the chitosan composite material is as follows:

[0037] The chitosan is added to an acidic aqueous solution and dissolved to obtain a chitosan aqueous solution;

[0038] The porous carrier is dispersed into the chitosan aqueous solution, stirred for 1-24 h, and the solid is separated to obtain a pre-coated carrier;

[0039] The pre-coated carrier is reacted with a cross-linking agent to obtain the chitosan composite material.

[0040] The first porous carrier and the second porous carrier are mixed uniformly at a weight ratio of 1:2-3:1, and the porous carrier obtained is dispersed in a chitosan aqueous solution. The chitosan is pre-coated on the surface of the porous carrier, and then the chitosan is cross-linked to obtain the chitosan composite material. There is no particular limitation to the method of reacting the pre-coated carrier with the cross-linking agent. For example, the pre-coated carrier can be dispersed in an organic solvent containing the cross-linking agent to perform the cross-linking reaction. The solid is separated by filtration, centrifugation, or the like, and then washed to remove the unreacted cross-linking agent, and dried to obtain the chitosan composite material.

[0041] In some embodiments, the degree of deacetylation of the chitosan is not less than 85%, and the concentration of the chitosan aqueous solution is 0.5-5wt%. If the degree of deacetylation of the chitosan is insufficient, the solubility in the acidic aqueous solution (pH can be 3-5) is not good. For example, the degree of deacetylation of the chitosan can be any value or any value between any of 85%, 88%, 90%, 92%, 95%, and the concentration of the chitosan aqueous solution can be any value or any value between any of 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, and the like. There is no particular limitation to the molecular weight of the chitosan, and the number average molecular weight can be 10,000-500,000.

[0042] In some embodiments, the weight ratio of the chitosan to the porous carrier is 1:1-1:20. For example, the weight ratio can be any value or any value between any of 1:1, 1:3, 1:5, 1:6, 1:8, 1:10, 1:12, 1:13, 1:15, 1:17, 1:18, 1:20, and the like. Further, the weight ratio of the chitosan to the porous carrier can be 1:5-1:20.

[0043] In some embodiments, the porous carrier is pretreated first;

[0044] The pretreatment includes acid washing, neutralization, and calcination activation in sequence. Through the pretreatment, the activity of the porous carrier can be improved and the pore size can be enlarged, which is beneficial to improve the adsorption performance. The acid washing can use dilute sulfuric acid (such as 0.1-5mol / L) for 0.5-24h; the neutralization can use saturated sodium bicarbonate for washing, and then use clean water for washing; the calcination temperature can be 200-500℃, and the calcination time can be 0.5-2h.

[0045] In some embodiments, the cross-linking agent is selected from one or a combination of two or more of glutaraldehyde, epichlorohydrin and polyisocyanate compound. Cross-linking of chitosan with a cross-linking agent can improve the stability and adsorption performance of the chitosan composite material, and avoid chitosan from falling off the surface of the porous carrier during the adsorption process (such as in the stomach, intestines and the like of animals), leading to decomposition of the composite material. Glutaraldehyde, epichlorohydrin and polyisocyanate compound are commonly used cross-linking agents for chitosan. For the polyisocyanate compound, it can be a diisocyanate monomer and its trimer, such as HDI, TDI, IPDI, HMDI, HDI trimer, IPDI trimer, etc., or an adduct of a diisocyanate monomer and a polymeric diol (such as a polyether diol, a polyester diol, etc.). There is no particular limitation on the amount of the cross-linking agent, and the amount of the cross-linking agent is determined according to the extent of cross-linking of chitosan.

[0046] Further, the cross-linking agent is selected from a polyisocyanate compound having a number average molecular weight of 300-3300. That is, the cross-linking agent is an adduct of a diisocyanate monomer and its trimer and a polymeric diol, which can avoid the cross-linking density of chitosan being too large and thereby affecting the adsorption performance of chitosan.

[0047] On the other hand, the present application also provides a composite feed additive comprising the chitosan composite material according to any one of the embodiments described above. The chitosan composite material according to the present application can be used to prepare a composite feed additive, which can exhibit the adsorption performance of the chitosan composite material for heavy metal ions. When the chitosan composite material is in the animal body, it can adsorb heavy metal ions in the animal body or in the feed, thereby reducing the absorption and / or accumulation of heavy metal ions by the animal. For the chitosan composite material according to the present application as a feed additive, the amount of the chitosan composite material added to the feed can be 0.2-2% by weight of the feed.

[0048] The technical solutions of the present application are further described and explained below according to various embodiments. Unless otherwise specified, the parts in the following embodiments are parts by weight.

[0049] Example 1

[0050] The porous carrier is composed of natural zeolite with an average particle size of 90 μm and natural zeolite with an average particle size of 20 μm at a weight ratio of 1:2.

[0051] The degree of deacetylation of the chitosan is 90%, and the number average molecular weight is 200,000. 1 part of chitosan is added to an acidic aqueous solution and dissolved to prepare a chitosan aqueous solution with a concentration of 1.5 wt%;

[0052] 5 parts of the porous carrier are added to the above chitosan aqueous solution, ultrasonically dispersed for 10 min, and then stirred for 6 h. The solid is then separated by suction filtration and washed with clean water for 2 times, and dried in an oven at 60°C overnight to obtain a pre-coated carrier.

[0053] The 1 part of the pre-coated support was dispersed in 50 parts of butyl acetate (containing 2 parts of glutaraldehyde) and stirred for 2 h. The solid was separated by suction filtration and immersed in pure water for 2 h, then suction filtered and separated, and washed twice with anhydrous ethanol. The solid was dried in an oven at 60°C overnight to obtain a chitosan composite material.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that in Example 1, 5 parts of the porous support is replaced by 5 parts of natural zeolite with an average particle size of 90 μm in Example 1. The remaining steps remain unchanged.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that in Example 1, 5 parts of the porous support is replaced by 5 parts of natural zeolite with an average particle size of 20 μm in Example 1. The remaining steps remain unchanged.

[0058] Comparative Example 3

[0059] Pre-coated support in Example 1.

[0060] Example 2

[0061] The difference between this example and Example 1 is that in Example 1, 2 parts of glutaraldehyde is replaced by 2 parts of HMDI. The remaining steps remain unchanged.

[0062] Example 3

[0063] The difference between this example and Example 2 is that in Example 2, 2 parts of HMDI is replaced by 2 parts of HMDI prepolymer. The remaining steps remain unchanged.

[0064] The NCO content of the HMDI prepolymer is 14.3 wt%, which is obtained by reacting HMDI with PPG with a number average molecular weight of 600.

[0065] Example 4

[0066] The difference between this example and Example 3 is that in Example 3, the HMDI prepolymer is adjusted from 2 parts to 5 parts. The remaining steps remain unchanged.

[0067] Example 5

[0068] The difference between this example and Example 4 is that in Example 3, the HMDI prepolymer is replaced by an equal weight of HDI prepolymer. The remaining steps remain unchanged.

[0069] The NCO content of the HDI prepolymer is 9.6 wt%, which is obtained by reacting HDI with PPG with a number average molecular weight of 1600.

[0070] Example 6

[0071] The porous carrier is composed of natural zeolite with an average particle size of 140 μm and natural zeolite with an average particle size of 30 μm at a weight ratio of 1:1.

[0072] The degree of deacetylation of the chitosan is 90%, and the number average molecular weight is 100,000. 1 part of the chitosan is added to an acidic aqueous solution and dissolved to prepare a chitosan aqueous solution with a concentration of 1 wt%;

[0073] 20 parts of the porous carrier are added to the above chitosan aqueous solution, ultrasonically dispersed for 15 min, and then stirred for 12 h. After that, the solid is separated by suction filtration and washed with clean water for 2 times, and dried in an oven at 60°C overnight to obtain a pre-coated carrier;

[0074] 1 part of the above pre-coated carrier is dispersed in 50 parts of butyl acetate (containing 4 parts of the HMDI prepolymer in Example 3), and the stirring is continued for 1 h. The solid is separated by suction filtration and soaked in pure water for 3 h, and then separated by suction filtration and washed with anhydrous ethanol for 2 times. The solid is dried in an oven at 60°C overnight to obtain a chitosan composite material.

[0075] Example 7

[0076] The difference between this example and Example 6 is that in Example 6, the weight ratio of the natural zeolite with an average particle size of 140 μm and the natural zeolite with an average particle size of 30 μm is adjusted from 1:1 to 3:1. The remaining steps remain unchanged.

[0077] I. In vitro heavy metal ion adsorption performance test

[0078] 0.2 g of the composite material to be tested is added to 100 ml of a Pb 2+ aqueous solution (the concentration C0 of Pb 2+ is 10 ppm), and adsorbed to saturation at room temperature. The concentration C1 of Pb 2+ in the solution is tested by atomic absorption spectrophotometry, and the removal rate is calculated. The removal rate = (C0-C1) / C0 x 100%. The results are shown in Table 1 below.

[0079] Table 1

[0080] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 2 Removal rate / % 90.5 82.1 80.4 65.9 91.0 Example 3 Example 4 Example 5 Example 6 Example 7 Removal rate / % 94.2 93.7 94.1 93.5 92.8

[0081] From the data in Table 1 above, it can be seen that the chitosan composite material of the present application has a good removal effect on the heavy metal ion Pb 2+ , and the removal effect can be further improved by using an isocyanate crosslinking agent with a larger molecular weight.

[0082] II. In vivo heavy metal ion adsorption performance test

[0083] The basic feed formula for broiler chickens is: 56.5% corn, 3% soybean oil, 33.7% soybean meal, 1% fish meal, 3% rapeseed meal, 1.4% calcium hydrogen phosphate, 1.1% stone powder, and 0.3% salt.

[0084] Seventy 1-day-old broiler chickens were used to test the composite materials of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 3. Ten of the chickens were randomly selected for each test and used as a test group, and were fed with the basic feed + 10 ppm lead + 1% of the composite material to be tested, which was mixed in advance. Of the remaining 20 chickens, 10 were randomly selected as a control group and were fed with the basic feed, and the remaining 10 were used as a toxic group and were fed with the basic feed + 10 ppm lead, which was mixed in advance. The chickens were raised for 42 days, and the average daily weight gain was measured, and the lead content in the breast muscle, liver, and kidney was measured. The results are shown in Table 2 below.

[0085] Table 2

[0086]

[0087] Therefore, the chitosan composite material of the present application can improve the adsorption of heavy metal ions when used as a feed additive in feed, and can prevent the accumulation of heavy metal ions in the animal body.

[0088] The basic principles, main features and advantages of the present application have been shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, which are only preferred embodiments of the present application and cannot limit the scope of the present application. Equivalent changes and modifications made in accordance with the scope and content of the present patent are also within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A chitosan composite material, characterized in that: comprising cross-linked chitosan and a porous carrier; The cross-linked chitosan is coated on the surface of the porous carrier; The porous support comprises a first porous support and a second porous support; The average particle size of the first porous carrier is 80-150 μm, and the average particle size of the second porous carrier is 10-30 μm.

2. The chitosan composite material according to claim 1, characterized in that The first porous carrier and the second porous carrier are independently selected from one or a combination of two or more of zeolite, porous ceramics, mesoporous silica, activated carbon and expanded perlite.

3. The chitosan composite material according to claim 1, characterized in that The weight ratio of the first porous carrier to the second porous carrier is 1:2-3:

1.

4. The chitosan composite material according to any one of claims 1 to 3, characterized in that The preparation method of the chitosan composite material is: Chitosan is added into an acidic aqueous solution and dissolved to obtain a chitosan aqueous solution; Dispersing the porous carrier into the chitosan aqueous solution, stirring for 1-24 hours, and separating the solid to obtain a pre-coated carrier; The pre-coated carrier is reacted with a cross-linking agent to obtain the chitosan composite material.

5. The chitosan composite material according to claim 4, characterized in that The deacetylation degree of the chitosan is not less than 85%, and the concentration of the chitosan aqueous solution is 0.5-5 wt%.

6. The chitosan composite material according to claim 4, characterized in that The weight ratio of the chitosan to the porous carrier is 1:1-1:

20.

7. The chitosan composite material according to claim 4, characterized in that The porous carrier is first pretreated; The pretreatment includes pickling, neutralization and calcination activation in sequence.

8. The chitosan composite material according to claim 4, characterized in that The cross-linking agent is selected from one or a combination of two or more of glutaraldehyde, epichlorohydrin and polyisocyanate compounds.

9. The chitosan composite material according to claim 8, characterized in that The cross-linking agent is selected from polyisocyanate compounds with a number average molecular weight of 300-2300.

10. A composite feed additive, characterized in that: The chitosan composite material comprises the chitosan composite material according to any one of claims 1 to 9.

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