Tobacco stem shell biochar as well as preparation method and application thereof

Abstract

The invention discloses tobacco stem 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 stem shell biochar comprises the following steps: performing high-temperature pyrolysis on tobacco stem shells in an inert atmosphere, and then washing, drying, grinding and sieving to obtain the tobacco stem shell biochar. The tobacco stem shell is used as a raw material, the content of K and Cl elements in the tobacco stem shell is high, the K element is easy to gasify at high temperature and can serve as a self-template in the carbonization process, the original structure of a precursor is better reserved, and the K element can catalyze decomposition of a carbon source and formation of a carbon structure; the Cl element can form small molecules in the carbonization process, and can provide more micropores for the material after volatilization, so that the tobacco stem shell biochar with significantly increased specific surface area, developed micropore number and significantly increased micropore area is obtained after high-temperature pyrolysis; and the tobacco stem shell biochar can well separate chlorogenic acid and nicotine in the tobacco waste.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon materials, and in particular relates to a tobacco stem shell biochar and a preparation method and application thereof. Background Art

[0002] Chlorogenic acid (5-CQA) is an ester compound formed by the condensation of caffeic acid and quinic acid. Due to the different esterification sites, chlorogenic acid also includes two configurations: neochlorogenic acid (3-CQA) and cryptochlorogenic acid (4-CQA), which are collectively referred to as chlorogenic acid isomers. During the research process, they are referred to as chlorogenic acid and studied together. The antioxidant properties of chlorogenic acid give it antibacterial, anti-inflammatory, anti-cancer and hypoglycemic effects. Studies have also shown that chlorogenic acid also has preventive and therapeutic effects on chronic diseases and cardiovascular diseases. Nicotine is a characteristic compound in tobacco waste and is the active ingredient that many researchers have focused on. However, 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 huge specific surface area and rich surface functional groups. Its developed pore structure generated during pyrolysis gives it strong adsorption properties. Therefore, using biochar to separate chlorogenic acid and nicotine from tobacco waste and purify chlorogenic acid and nicotine is an effective way to utilize tobacco waste resources.

[0004] At present, there are no research reports on the separation and purification of chlorogenic acid and nicotine in tobacco waste using tobacco stalk husk biochar. Summary of the invention

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

[0006] In a first aspect, the present invention provides a method for preparing tobacco husk biochar, comprising the following steps: placing the tobacco husk in an inert atmosphere for high-temperature pyrolysis, and then washing, drying, grinding, and screening to obtain tobacco husk biochar; wherein the high-temperature pyrolysis temperature is 500-700°C and the time is 20-40min.

[0007] In the present invention, the inventors have found that the contents of K and Cl elements in tobacco stem husks are relatively high, wherein K element is easily gasified at high temperature, can act as a self-template during the carbonization process, better retain the original structure of the precursor, and can catalyze the decomposition of the carbon source and the formation of the carbon structure; Cl element can form small molecules during the carbonization process, which can provide more micropores for the material after volatilization. Therefore, with tobacco stem husks as raw materials, tobacco stem husk biochar with significantly increased specific surface area, developed micropores, and significantly increased micropore area can be obtained after high-temperature pyrolysis; in addition, the preparation process of the present invention is simple, the raw materials are cheap and easily available, and large-scale production is convenient.

[0008] In the method for preparing tobacco stem husk biochar provided by the present invention, the temperature of high-temperature pyrolysis can be, for example, 500°C, 550°C, 600°C, 650°C, 700°C or other values ​​within the range; the time can be, for example, 20 min, 25 min, 30 min, 35 min, 40 min or other values ​​within the range.

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

[0010] It is understandable that the inert gas can be conventionally selected according to actual use requirements. In the present invention, the inert gas preferably includes at least one of nitrogen and argon.

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

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

[0013] It is understandable that the drying temperature and time can be conventionally selected according to actual use needs. In the present invention, the drying temperature is preferably 70-90° C., and the drying time is preferably 4-8 hours.

[0014] In some embodiments, the sieving step specifically includes: sieving using a sieve with a pore size of 80-120 mesh (for example, 80 mesh, 90 mesh, 100 mesh, 110 mesh, 120 mesh or other values ​​within the range).

[0015] In some embodiments, before placing the tobacco stem husk in an inert atmosphere for high-temperature pyrolysis, the step of pretreating the tobacco stem husk is also included. The pretreatment step specifically includes: drying the tobacco stem husk for 18-32 hours, for example, 18 hours, 22 hours, 26 hours, 30 hours, 32 hours or other values ​​within the range, at a temperature of 70-90°C (for example, 70°C, 75°C, 80°C, 85°C, 90°C or other values ​​within the range); crushing and passing through a 40-80 mesh (for example, 40 mesh, 50 mesh, 60 mesh, 70 mesh, 80 mesh or other values ​​within the range) sieve.

[0016] In the present invention, by pre-treating the tobacco stem husk, it is convenient to better perform high-temperature pyrolysis on the tobacco stem husk.

[0017] In a second aspect, the present invention provides a tobacco stem husk biochar prepared by any of the preparation methods described above.

[0018] In a third aspect, the present invention provides the use of the above-mentioned tobacco stem husk biochar in separating chlorogenic acid and nicotine in tobacco waste.

[0019] In some embodiments, separation of chlorogenic acid and nicotine in tobacco waste comprises the following steps: S1, adding tobacco waste to an acid solution, stirring for reaction, filtering to obtain a first solution; S2, adding tobacco husk biochar to the first solution, adjusting the pH value of the solution, and obtaining tobacco husk biochar with chlorogenic acid adsorbed on the surface and a second solution containing nicotine after adsorption.

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

[0021] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention uses tobacco stem husk as raw material, wherein the content of K and Cl elements in the tobacco stem husk is relatively high, the K element is easily gasified at high temperature, and can act as a self-template during the carbonization process to better retain 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 during the carbonization process, and can provide more micropores for the material after volatilization, therefore, after high-temperature pyrolysis, the tobacco stem husk biochar with significantly increased specific surface area, developed micropores, and significantly increased micropore area is obtained; in addition, the tobacco stem husk biochar can better separate chlorogenic acid and nicotine in tobacco waste, therefore, it has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The nitrogen adsorption-desorption curve (A) and pore size distribution diagram (B) of the tobacco husk biochar prepared in Example 1 of the present invention; Figure 2 The nitrogen adsorption and desorption curve (A) and pore size distribution diagram (B) of the tobacco stem biochar prepared in Comparative Example 1 of the present invention; Figure 3The nitrogen adsorption-desorption curve (A) and pore size distribution diagram (B) of the tobacco husk biochar prepared in Comparative Example 2 of the present invention; Figure 4 The nitrogen adsorption-desorption curve (A) and pore size distribution diagram (B) of the tobacco husk biochar prepared in Comparative Example 3 of the present invention; Figure 5A is a chromatogram of a first solution obtained after the tobacco waste sample is treated in the present invention; Figure 5B A chromatogram of a second solution obtained by treating a first solution with tobacco stem shell biochar in the present invention; Figure 5C This is a chromatogram of the third solution obtained after the first solution is treated with tobacco stem biochar in the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The experimental methods without specific conditions in the examples are usually carried out according to conventional conditions and conditions described in the manual, or according to conditions recommended by the manufacturer. The general equipment, materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0025] Example 1 A method for preparing tobacco stem husk biochar comprises the following steps: 1) Take fresh tobacco stems, peel off the tobacco stem husks, and place them in a forced air drying oven at 80°C for 24 hours; crush the dried tobacco stem husks, and pass them through a 60-mesh sieve to obtain pretreated tobacco stem husks; 2) The pretreated tobacco stem husk obtained in step 1) is placed in a quartz boat, and the quartz boat is placed at the entrance of a tube furnace (filled with nitrogen), and the temperature is raised to 550°C at a rate of 10°C / min, and the quartz boat is pushed into the heating zone for pyrolysis for 30 minutes, and then the quartz boat is pulled out and taken out after cooling to room temperature; then, it is washed with a hydrochloric acid solution with a molar concentration of 0.1 mol / L for 8 minutes, and dried at a temperature of 80°C for 6 hours, and after grinding and passing through a 100-mesh sieve, the tobacco stem husk biochar is obtained.

[0026] Example 2 A method for preparing tobacco stem husk biochar comprises the following steps: 1) Take fresh tobacco stems, peel off the tobacco stem husks, and place them in a forced air drying oven at 80°C for 24 hours; crush the dried tobacco stem husks, and pass them through a 60-mesh sieve to obtain pretreated tobacco stem husks; 2) The pretreated tobacco stem husk obtained in step 1) is placed in a quartz boat, and the quartz boat is placed at the entrance of a tube furnace (filled with nitrogen), and the temperature is raised to 500°C at a rate of 10°C / min, and the quartz boat is pushed into the heating zone for pyrolysis for 40 minutes, and then the quartz boat is pulled out and taken out after cooling to room temperature; then, it is washed with a hydrochloric acid solution with a molar concentration of 0.1 mol / L for 8 minutes, and dried at a temperature of 80°C for 6 hours, and after grinding and passing through a 100-mesh sieve, tobacco stem husk biochar is obtained.

[0027] Example 3 A method for preparing tobacco stem husk biochar comprises the following steps: 1) Take fresh tobacco stems, peel off the tobacco stem husks, and place them in a forced air drying oven at 80°C for 24 hours; crush the dried tobacco stem husks, and pass them through a 60-mesh sieve to obtain pretreated tobacco stem husks; 2) The pretreated tobacco stem husk obtained in step 1) is placed in a quartz boat, and the quartz boat is placed at the entrance of a tube furnace (filled with nitrogen), and the temperature is raised to 700°C at a rate of 10°C / min, and the quartz boat is pushed into the heating zone for pyrolysis for 20 minutes, and then the quartz boat is pulled out and taken out after cooling to room temperature; then, it is washed with a hydrochloric acid solution with a molar concentration of 0.1 mol / L for 8 minutes, and dried at a temperature of 80°C for 6 hours, and after grinding and passing through a 100-mesh sieve, tobacco stem husk biochar is obtained.

[0028] Comparative Example 1 The preparation method of tobacco stem biochar in this comparative example is basically the same as that in Example 1, except that the tobacco stem shell is replaced with tobacco stem to obtain tobacco stem biochar.

[0029] Comparative Example 2 The preparation method of tobacco stem husk 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.

[0030] Comparative Example 3 The preparation method of tobacco stem husk biochar in this comparative example is basically the same as that in Example 1, except that, in step 2), the temperature is raised to 800°C.

[0031] Performance Testing The performance tests were conducted on the tobacco stem shell biochars prepared in Examples 1-3 and Comparative Examples 2-3 and the tobacco stem biochar prepared in Comparative Example 1. The results were as follows: Figure 1-4 And as shown in Table 1 below.

[0032] Table 1 Performance test results

[0033] from Figure 1-4 It can be seen from Table 1 that the tobacco husk biochar prepared in Examples 1-3 has a larger specific surface area, a well-developed number of micropores, and a larger micropore area; the specific surface area, the number of micropores, and the micropore area of ​​the tobacco husk biochar prepared in Comparative Example 1 all decrease to a certain extent; the high-temperature pyrolysis temperature 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 husk biochar all decrease significantly; the above results indicate that, in the present invention, using specific tobacco husks as raw materials and subjected to a specific high-temperature pyrolysis temperature for treatment, tobacco husk biochar with a larger specific surface area, a well-developed number of micropores, and a larger micropore area can be obtained.

[0034] Application Testing The tobacco stem husk biochar prepared in Example 1 and the tobacco stem biochar prepared in Comparative Example 1 were used to conduct a test on the separation of chlorogenic acid and nicotine in tobacco waste.

[0035] Specifically, the steps include: S1. Transfer 2.5 g of tobacco waste sample and 100 mL of hydrochloric acid solution with a pH value of 3.0 into a conical flask, add a magnetic rotor, and seal it with tin foil; place the treated conical flask in a water bath, then adjust the temperature to 80° C., adjust the speed to 200 rpm, and extract for 1 hour; after suction filtration, obtain the first solution; S2, adding the tobacco husk biochar to the first solution, adjusting the pH value of the solution to 5, and after adsorption for 30 minutes, obtaining the adsorbed tobacco husk biochar and the second solution; S3. Add tobacco stalk biochar to the first solution, adjust the pH value of the solution to 5, and after adsorption for 30 minutes, obtain the adsorbed tobacco stalk biochar and the third solution.

[0036] HR-LC-MS was used to detect the contents of chlorogenic acid and nicotine in the first solution, the second solution and the third solution (the chromatograms are shown in FIG. Figures 5A-5C As shown), the adsorption rate of chlorogenic acid and the retention rate of nicotine were obtained.

[0037] Among them, the adsorption rate of chlorogenic acid isomers by tobacco stalk husk biochar after adsorption was 99.937%, and the retention rate of nicotine in the second solution was 84.87%; the adsorption rate of chlorogenic acid isomers by tobacco stalk biochar after adsorption was 87.07%, and the retention rate of nicotine in the third solution was 41.388%; the above results indicate that the tobacco stalk husk biochar in the present invention can better separate chlorogenic acid and nicotine in tobacco waste.

[0038] In summary, in the present invention, tobacco stem husk is used as raw material, and after high-temperature pyrolysis, tobacco stem husk biochar with significantly increased specific surface area, developed number of micropores, and significantly increased micropore area is obtained. The tobacco stem husk biochar can better separate chlorogenic acid and nicotine in tobacco waste, and therefore has good application prospects.

[0039] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For matters that are not described in detail in some embodiments, reference may be made to the description in other embodiments.

[0040] The above-mentioned embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing tobacco stem husk biochar, characterized in that: The steps include: The tobacco stem husk is placed in an inert atmosphere for high-temperature pyrolysis, and then washed, dried, ground and sieved to obtain tobacco stem husk biochar; Wherein, the temperature of the high temperature pyrolysis is 500-700°C and the time is 20-40min.

2. The method for preparing tobacco stem husk biochar according to claim 1, characterized in that: The inert gas includes at least one of nitrogen and argon.

3. The method for preparing tobacco stem husk biochar according to claim 1, characterized in that: The washing step specifically includes: washing with an acid solution having a molar concentration of 0.05-0.15 mol / L, and the washing time is 5-10 min; 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 stem husk biochar according to claim 1, characterized in that: The drying step specifically includes: drying at a temperature of 70-90° C. for 4-8 hours.

5. The method for preparing tobacco stem husk biochar according to claim 1, characterized in that: The sieving step specifically includes: sieving using a sieve with an aperture of 80-120 meshes.

6. The method for preparing tobacco stem husk biochar according to claim 1, characterized in that: Before placing the tobacco stem husk in an inert atmosphere for high-temperature pyrolysis, the method further includes pre-treating the tobacco stem husk. The pre-treating step specifically includes drying the tobacco stem husk for 18-32 hours at a temperature of 70-90°C, crushing the husk, and passing it through a 40-80 mesh sieve.

7. A tobacco stem husk biochar prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the tobacco stem husk biochar as claimed in claim 7 in separating chlorogenic acid and nicotine in tobacco waste.

9. The use according to claim 8, characterized in that: The separation of chlorogenic acid and nicotine in tobacco waste comprises the following steps: S1, adding tobacco waste into an acid solution, stirring for reaction, and filtering to obtain a first solution; S2. Adding tobacco husk biochar to the first solution, adjusting the pH value of the solution, and obtaining tobacco husk biochar with chlorogenic acid adsorbed on the surface and a second solution containing nicotine after adsorption.

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

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