A tobacco stalk shell biochar and a preparation method and application thereof

Abstract

The application discloses a tobacco stalk shell biochar as well as a preparation method and application thereof, and belongs to the technical field of carbon materials. The preparation method of the tobacco stalk shell biochar comprises the following steps: placing tobacco stalk shells in an inert atmosphere to perform high-temperature pyrolysis, and then performing washing, drying, grinding and sieving to obtain the tobacco stalk shell biochar. The tobacco stalk shells are used as raw materials, the contents of K and Cl elements in the tobacco stalk shells are relatively high, the K element is easy to be gasified under high temperature, can act as a self-template in the carbonization process, better retains the original structure of the precursor, and can catalyze the decomposition of the carbon source and the formation of the carbon structure; the Cl element can form small molecules in the carbonization process, and after volatilization, can provide more micropores for the material. Therefore, the specific surface area of the tobacco stalk shell biochar obtained after high-temperature pyrolysis is significantly increased, the number of micropores is developed, and the micropore area is significantly increased; and the tobacco stalk shell biochar can better separate chlorogenic acid and nicotine in tobacco waste.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of carbon materials, and particularly relates to a tobacco stalk shell biochar as well as a preparation method and application thereof. BACKGROUND

[0002] Chlorogenic acid (5-CQA) is an ester compound condensed by caffeic acid and quinic acid. Due to the difference in esterification sites, chlorogenic acid also includes two configurations of neochlorogenic acid (3-CQA) and cryptochlorogenic acid (4-CQA), which are collectively referred to as chlorogenic acid isomers, and are simply referred to as chlorogenic acid and studied together in the research process. The antioxidant property of chlorogenic acid makes it have the effects of antibacterial, anti-inflammatory, anticancer and blood sugar lowering, and researches have also shown that chlorogenic acid also has the effects of prevention and treatment in chronic diseases and cardiovascular diseases. Nicotine is a characteristic compound in tobacco waste and is an effective ingredient focused by many researchers, but chlorogenic acid also exists in tobacco waste. Therefore, how to extract and purify chlorogenic acid, neochlorogenic acid, cryptochlorogenic acid and nicotine from tobacco waste is a difficult problem.

[0003] Biochar has a large specific surface area and rich surface functional groups, and the developed pore structure generated in the pyrolysis process makes it have strong adsorption performance. Therefore, using biochar to separate chlorogenic acid and nicotine in tobacco waste and realize the purification of chlorogenic acid and nicotine is an effective utilization way of resource utilization of tobacco waste.

[0004] At present, there is no research report on using tobacco stalk shell biochar to separate and purify chlorogenic acid and nicotine in tobacco waste. SUMMARY

[0005] The present application aims to provide a tobacco stalk shell biochar as well as a preparation method and application thereof. In the present application, the tobacco stalk shell is used as a raw material, and after high-temperature pyrolysis, a tobacco stalk shell biochar with a significantly increased specific surface area, a large number of micropores and a significantly increased micropore area is obtained. The tobacco stalk shell biochar can better separate chlorogenic acid and nicotine in tobacco waste, and therefore has good application prospects.

[0006] In a first aspect, the present application provides a preparation method of a tobacco stalk shell biochar, comprising the following steps: placing tobacco stalk shell in an inert atmosphere for high-temperature pyrolysis, and then after washing, drying, grinding and sieving, obtaining the tobacco stalk shell biochar; wherein the temperature of high-temperature pyrolysis is 500-700℃, and the time is 20-40min.

[0007] In the present application, the inventor has found that the content of K and Cl elements in the stalk shell is relatively high, wherein the K element is easy to gasify at high temperature, can act as a self-template in the carbonization process, and better retains the original structure of the precursor, and the K element can catalyze the decomposition of the carbon source and the formation of the carbon structure; the Cl element can form small molecules in the carbonization process, and after volatilization, it can provide more micropores for the material, therefore, the stalk shell biochar obtained by high-temperature pyrolysis of the stalk shell has a significantly increased specific surface area, a large number of micropores, and a significantly increased micropore area; in addition, the preparation process in the present application is simple, the raw material is cheap and easy to obtain, and it is convenient for large-scale production.

[0008] In the preparation method of the stalk shell biochar provided by the present application, the temperature of high-temperature pyrolysis can be, for example, 500℃, 550℃, 600℃, 650℃, 700℃, or other values within the range; the time can be, for example, 20min, 25min, 30min, 35min, 40min, or other values within the range.

[0009] In some embodiments, the inert gas includes at least one of nitrogen and argon.

[0010] It can be understood that the inert gas can be routinely selected according to actual needs, and in the present application, the inert gas preferably includes at least one of nitrogen and argon.

[0011] In some embodiments, the washing step specifically includes: using an acid solution with a molar concentration of 0.05-0.15mol / L (for example, 0.05mol / L, 0.07mol / L, 0.1mol / L, 0.13mol / L, 0.15mol / L, or other values within the range) for washing, and the washing time is 5-10min, for example, 5min, 6min, 7min, 8min, 9min, 10min, or other values within the range; wherein the acid solution is selected from at least one of a hydrochloric acid solution, a sulfuric acid solution, and a nitric acid solution.

[0012] In some embodiments, the drying step specifically includes: drying at a temperature of 70-90℃ (for example, 70℃, 75℃, 80℃, 85℃, 90℃, or other values within the range) for 4-8h, for example, 4h, 5h, 6h, 7h, 8h, or other values within the range.

[0013] It can be understood that the temperature and time of drying can be routinely selected according to actual needs, and in the present application, the temperature of drying is preferably 70-90℃, and the time is preferably 4-8h.

[0014] In some embodiments, the sieving step specifically comprises: sieving using a sieve with a mesh size of 80-120 mesh (e.g., can be 80 mesh, 90 mesh, 100 mesh, 110 mesh, 120 mesh, or other values within the range).

[0015] In some embodiments, before placing the tobacco stalk shell into an inert atmosphere for high-temperature pyrolysis, the method further comprises a step of pretreating the tobacco stalk shell, and the step of pretreating specifically comprises: drying the tobacco stalk shell at a temperature of 70-90℃ (e.g., can be 70℃, 75℃, 80℃, 85℃, 90℃, or other values within the range) for 18-32h (e.g., can be 18h, 22h, 26h, 30h, 32h, or other values within the range); crushing and sieving through a 40-80 mesh (e.g., can be 40 mesh, 50 mesh, 60 mesh, 70 mesh, 80 mesh, or other values within the range) sieve.

[0016] In the present application, by pretreating the tobacco stalk shell, the high-temperature pyrolysis of the tobacco stalk shell is facilitated.

[0017] In a second aspect, the present application provides a tobacco stalk shell biochar prepared by any of the above preparation methods.

[0018] In a third aspect, the present application provides use of the tobacco stalk shell biochar as described above in separating chlorogenic acid and nicotine from tobacco waste.

[0019] In some embodiments, the separating chlorogenic acid and nicotine from tobacco waste comprises the following steps: S1, adding the tobacco waste into an acid solution, stirring and reacting, filtering to obtain a first solution; S2, adding the tobacco stalk shell biochar into the first solution, adjusting the pH value of the solution, and adsorbing to obtain the tobacco stalk shell biochar with surface-adsorbed chlorogenic acid and a second solution containing nicotine.

[0020] In some embodiments, the mass concentration of the tobacco waste added is 0.02-0.03 g / mL, for example, can be 0.02 g / mL, 0.022 g / mL, 0.025 g / mL, 0.028 g / mL, 0.03 g / mL or other values in the range; the pH value of the acid solution is 2.5-3.5, for example, can be 2.5, 2.7, 3, 3.3, 3.5 or other values in the range; and the acid solution is selected from at least one of hydrochloric acid solution, sulfuric acid solution, nitric acid solution, the temperature of stirring reaction is 70-90℃, for example, can be 70℃, 75℃, 80℃, 85℃, 90℃ or other values in the range; the rotation speed is 180-220 rpm, for example, can be 180 rpm, 190 rpm, 200 rpm, 210 rpm, 220 rpm or other values in the range; the time is 0.5-1.5 h, for example, can be 0.5 h, 0.7 h, 1 h, 1.3 h, 1.5 h or other values in the range; in step S2, the mass concentration of the tobacco stalk shell biochar added is 30-50 g / L, for example, can be 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L or other values in the range; the pH value of the adjusted solution is 4.5-5.5, for example, can be 4.5, 4.7, 5, 5.3, 5.5 or other values in the range; the adsorption time is 20-40 min, for example, can be 20 min, 25 min, 30 min, 35 min, 40 min or other values in the range.

[0021] The beneficial effects of the present application are: different from the prior art, the present application uses tobacco stalk shell as raw material, wherein the content of K and Cl elements in the tobacco stalk shell is relatively high, K element is easy to gasify at high temperature, can act as a self-template in the carbonization process, better retains the original structure of the precursor, and K element can catalyze the decomposition of carbon source and the formation of carbon structure; Cl element can form small molecules in the carbonization process, and after volatilization, it can provide more micropores for the material, therefore, the tobacco stalk shell biochar obtained after high-temperature pyrolysis has a significantly increased specific surface area, a large number of micropores and a significantly increased micropore area; in addition, the tobacco stalk shell biochar can better separate chlorogenic acid and nicotine in tobacco waste, therefore, has good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Figure (A) is a nitrogen adsorption-desorption curve diagram and figure (B) is a pore size distribution diagram of the tobacco stalk shell biochar prepared in Example 1 of the present application;

[0023] Figure 2 Figure (A) is a nitrogen adsorption-desorption curve diagram and figure (B) is a pore size distribution diagram of the tobacco stalk shell biochar prepared in Comparative Example 1 of the present application;

[0024] Figure 3 Nitrogen adsorption-desorption curve (A) and pore size distribution (B) of the tobacco stem shell biochar prepared in the present application comparative example 2;

[0025] Figure 4 Nitrogen adsorption-desorption curve (A) and pore size distribution (B) of the tobacco stem shell biochar prepared in the present application comparative example 3;

[0026] Figure 5A Chromatogram of the first solution obtained after treatment of the tobacco waste sample in the present application;

[0027] Figure 5B Chromatogram of the second solution obtained after treatment of the first solution with the tobacco stem shell biochar in the present application;

[0028] Figure 5C Chromatogram of the third solution obtained after treatment of the first solution with the tobacco stem biochar in the present application. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0030] The experimental methods not specified in the embodiments are usually performed according to the conventional conditions and the conditions described in the manual, or according to the conditions suggested by the manufacturers. The general equipment, materials, reagents, etc. used are commercially available, unless otherwise specified.

[0031] Embodiment 1

[0032] A preparation method of a tobacco stem shell biochar, comprising the following steps:

[0033] 1) Fresh tobacco stems are taken, the tobacco stem shells are peeled off, and placed in a forced air drying oven at a temperature of 80℃ for 24h. The dried tobacco stem shells are crushed, and passed through a 60 mesh sieve to obtain pretreated tobacco stem shells;

[0034] 2) The pretreated tobacco stem shells obtained in step 1) are placed in a quartz boat, and the quartz boat is placed at the inlet of a tube furnace (filled with nitrogen) and programmed to 550℃ at a rate of 10℃ / min. The quartz boat is pushed into the heating zone and pyrolyzed for 30min. Then the quartz boat is pulled out and taken out after being cooled to room temperature. Then the quartz boat is washed with a hydrochloric acid solution with a molar concentration of 0.1mol / L for 8min, and dried at a temperature of 80℃ for 6h. After grinding and passing through a 100 mesh sieve, the tobacco stem shell biochar is obtained.

[0035] Example 2

[0036] A preparation method of tobacco stalk shell biochar, comprising the following steps:

[0037] 1) Take fresh tobacco stalks, peel off the tobacco stalk shell, and place them in a forced air drying oven at a temperature of 80°C for 24h; grind the dried tobacco stalk shell, pass it through a 60 mesh sieve, and obtain pretreated tobacco stalk shell;

[0038] 2) Put the pretreated tobacco stalk shell obtained in step 1) into a quartz boat, and place the quartz boat at the inlet of a tube furnace (filled with nitrogen), and program the temperature to rise to 500°C at a rate of 10°C / min, push the quartz boat into the heating zone, pyrolyze for 40min, then pull out the quartz boat, and take it out after it cools to room temperature; then wash it with a 0.1 mol / L hydrochloric acid solution for 8min, and dry it at a temperature of 80°C for 6h, then grind and pass it through a 100 mesh sieve to obtain tobacco stalk shell biochar.

[0039] Example 3

[0040] A preparation method of tobacco stalk shell biochar, comprising the following steps:

[0041] 1) Take fresh tobacco stalks, peel off the tobacco stalk shell, and place them in a forced air drying oven at a temperature of 80°C for 24h; grind the dried tobacco stalk shell, pass it through a 60 mesh sieve, and obtain pretreated tobacco stalk shell;

[0042] 2) Put the pretreated tobacco stalk shell obtained in step 1) into a quartz boat, and place the quartz boat at the inlet of a tube furnace (filled with nitrogen), and program the temperature to rise to 700°C at a rate of 10°C / min, push the quartz boat into the heating zone, pyrolyze for 20min, then pull out the quartz boat, and take it out after it cools to room temperature; then wash it with a 0.1 mol / L hydrochloric acid solution for 8min, and dry it at a temperature of 80°C for 6h, then grind and pass it through a 100 mesh sieve to obtain tobacco stalk shell biochar.

[0043] Comparative Example 1

[0044] The preparation method of tobacco stalk biochar in this comparative example is basically the same as that in Example 1, except that the tobacco stalk shell is replaced by tobacco stalk to obtain tobacco stalk biochar.

[0045] Comparative Example 2

[0046] The preparation method of tobacco stalk shell biochar in this comparative example is basically the same as that in Example 1, except that in step 2), the temperature is raised to 300°C.

[0047] Comparative Example 3

[0048] The preparation method of the tobacco stalk shell biochar in the present comparative example is basically the same as that in Example 1, except that in step 2), the temperature is raised to 800℃.

[0049] Performance test

[0050] The tobacco stalk shell biochar prepared in Examples 1-3 and Comparative Examples 2-3 and the tobacco stalk biochar prepared in Comparative Example 1 were subjected to performance test, and the results are shown in Table 1 below. Figures 1-4 and Table 1 below.

[0051] Table 1 Performance test results

[0052]

[0053] From Figures 1-4 As can be seen from Table 1, the tobacco stalk shell biochar prepared in Examples 1-3 has a large specific surface area, a large number of micropores and a large micropore area; the specific surface area, the number of micropores and the micropore area of the tobacco stalk biochar prepared in Comparative Example 1 all decrease to a certain extent; the temperature of high-temperature pyrolysis in Comparative Examples 2 and 3 is too low or too high, and it is found that the specific surface area, the number of micropores and the micropore area of the prepared tobacco stalk shell biochar all decrease significantly; the above results show that, after the specific tobacco stalk shell is treated by the specific high-temperature pyrolysis temperature, the tobacco stalk shell biochar with a large specific surface area, a large number of micropores and a large micropore area can be obtained.

[0054] Application test

[0055] The tobacco stalk shell biochar prepared in Example 1 and the tobacco stalk biochar prepared in Comparative Example 1 were used to carry out separation test of chlorogenic acid and nicotine in tobacco waste.

[0056] Specifically, the following steps are included:

[0057] S1, 2.5g of tobacco waste sample and 100mL of hydrochloric acid solution with pH value of 3.0 were transferred to a conical flask, a magnetic rotor was added, and the conical flask was sealed with tin foil paper; the treated conical flask was placed in a water bath kettle, and then the temperature was adjusted to 80℃, and the rotation speed was adjusted to 200rpm, and the extraction was carried out for 1h; after suction filtration, a first solution was obtained;

[0058] S2, the tobacco stalk shell biochar was added to the first solution, the pH value of the solution was adjusted to 5, and after adsorption for 30min, the adsorbed tobacco stalk shell biochar and a second solution were obtained;

[0059] S3, the tobacco stalk biochar was added to the first solution, the pH value of the solution was adjusted to 5, and after adsorption for 30min, the adsorbed tobacco stalk biochar and a third solution were obtained.

[0060] The first solution, the second solution and the third solution are detected by HR-LC-MS to detect the content of chlorogenic acid and nicotine (chromatograms are shown in Figures 5A-5C The adsorption rate of chlorogenic acid and the retention rate of nicotine are obtained.

[0061] The adsorption rate of chlorogenic acid isomers of the adsorbed tobacco stem shell biochar is 99.937%, and the retention rate of nicotine in the second solution is 84.87%; the adsorption rate of chlorogenic acid isomers of the adsorbed tobacco stem biochar is 87.07%, and the retention rate of nicotine in the third solution is 41.388%; the above results show that the tobacco stem shell biochar in the application can better separate chlorogenic acid and nicotine in tobacco waste.

[0062] In summary, in the application, the tobacco stem shell is used as a raw material, and after high-temperature pyrolysis, the specific surface area of the tobacco stem shell biochar is significantly increased, the number of micropores is developed, and the micropore area is significantly increased. The tobacco stem shell biochar can better separate chlorogenic acid and nicotine in tobacco waste, and therefore has good application prospects.

[0063] It should be noted that each of the above embodiments belongs to the same inventive concept, and the description of each embodiment has its own emphasis. If the description is not exhaustive in some embodiments, the description in other embodiments can be referred to.

[0064] The above-described embodiments only express the implementation of the application, and the description is more specific and detailed, but it should not be construed as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the inventive concept, a number of modifications and improvements can be made, which are within the scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A method for preparing biochar from tobacco stalk shells, characterized in that, Includes the following steps: The outer shell of the tobacco stalk is placed in an inert atmosphere for high-temperature pyrolysis, and then washed, dried, ground and sieved to obtain tobacco stalk biochar. The high-temperature pyrolysis is performed at a temperature of 500-550℃ for a time of 20-40 minutes. Before placing the tobacco stalk shell in an inert atmosphere for high-temperature pyrolysis, a pretreatment step is also included. The pretreatment step specifically includes: drying the tobacco stalk shell for 18-32 hours at a temperature of 70-90℃, and then crushing and passing it through a 40-80 mesh sieve.

2. The method for preparing tobacco straw shell biochar according to claim 1, characterized in that, The inert atmosphere includes at least one of nitrogen and argon.

3. The method for preparing tobacco straw shell biochar according to claim 1, characterized in that, The washing step specifically includes: washing with an acid solution with a molar concentration of 0.05-0.15 mol / L for 5-10 minutes; The acid solution is selected from at least one of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution.

4. The method for preparing tobacco straw shell biochar according to claim 1, characterized in that, The drying step specifically includes drying for 4-8 hours at a temperature of 70-90℃.

5. The method for preparing tobacco stalk biochar according to claim 1, characterized in that, The sieving step after high-temperature pyrolysis specifically includes sieving using a sieve with an aperture of 80-120 mesh.

6. A tobacco stalk shell biochar prepared by the preparation method according to any one of claims 1-5.

7. The application of the tobacco stalk shell biochar as described in claim 6 in the separation of chlorogenic acid and nicotine from tobacco waste.

8. The application according to claim 7, characterized in that, The separation of chlorogenic acid and nicotine from tobacco waste includes the following steps: S1. Add tobacco waste to an acid solution, stir and react, then filter to obtain the first solution; S2. Add tobacco husk biochar to the first solution, adjust the pH value of the solution, and after adsorption, obtain tobacco husk biochar with chlorogenic acid adsorbed on the surface and a second solution containing nicotine.

9. The application according to claim 8, characterized in that, In step S1, the concentration of the added tobacco waste is 0.02-0.03 g / mL, the pH of the acid solution is 2.5-3.5, and the acid solution is selected from at least one of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution. The stirring reaction temperature is 70-90℃, the stirring speed is 180-220 rpm, and the time is 0.5-1.5 h. In step S2, the mass concentration of the added tobacco stalk biochar is 30-50 g / L, the pH of the solution is adjusted to 4.5-5.5, and the adsorption time is 20-40 min.

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