Preparation method and application of hydrogen peroxide modified peanut shell biochar

Abstract

The application provides a preparation method and application of hydrogen peroxide modified peanut shell biochar, and belongs to the technical field of adsorbents; the preparation method comprises the following steps: reacting epoxy soybean oil and peanut shells to obtain pretreated peanut shells, then modifying and treating the pretreated peanut shells by using a hydrogen peroxide solution, introducing nitrogen, carbonizing at 500-700 DEG C, cooling, crushing, sieving, and obtaining hydrogen peroxide modified peanut shell biochar; the preparation method is easy to popularize and large-scale production and application, and raw materials are cheap and easy to obtain; the hydrogen peroxide modified peanut shell biochar can effectively adsorb herbicides in soil, greatly reduces the migration and biological hazards of the herbicides, and gradually decomposes and mineralizes the adsorbed herbicides into carbon dioxide and water by using the specific degradation capacity of soil microorganisms, and the carbon dioxide and water are absorbed by plants and enter a natural circulation state, so that the soil herbicide pollution can be treated and the soil can be improved, and the hydrogen peroxide modified peanut shell biochar has good economic, social and ecological benefits and a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adsorbent, in particular to a preparation method and application of hydrogen peroxide modified peanut shell biochar. BACKGROUND

[0002] In recent years, due to the large use of chemical herbicides, and the migration and slow degradation of herbicide pollutants, which are easy to accumulate in soil, pollute the soil, and then directly or indirectly produce some biological hazards, which have the characteristics of strong enrichment in biological body, great toxicity, concealment and long-term, and seriously pollute the environment and threaten human health, therefore, it is of great significance to develop biochar with strong adsorption capacity and stability for the prevention and control of herbicide pollutants.

[0003] Biochar is a carbon-rich material obtained by pyrolysis or hydrothermal carbonization of biomass materials under the condition of air isolation, which has a large specific surface area and rich oxygen-containing functional groups, and is a high-efficiency and inexpensive adsorbent, catalyst, and can also be used for layering, refining, concentrating and fading. Studies have shown that single biochar has very limited adsorption effect on pollutants, and needs to be modified to improve the adsorption performance of biochar. It is found that the surface of NaOH modified rice husk biochar is rough, and the specific surface area and pore volume are increased to different degrees; potassium permanganate solution is used as an activator to prepare chestnut shell biochar, and the maximum adsorption capacity of the material for Cr(VI) is 61.31mg / g.

[0004] Peanut shell is a typical agricultural waste in China, and the annual output of peanut shell in China is about 5 million tons. At present, except for a small part used as feed, most of it is discarded or directly burned, and the utilization rate is low, which causes serious waste of resources and air pollution. Preparing biochar from peanut shell at high temperature can not only effectively solve the disposal problem of peanut shell and realize resource utilization, but also can be used as an adsorbent to control pollution and achieve the purpose of waste treatment.

[0005] However, the single peanut shell biochar prepared by the traditional method has very limited adsorption capacity, in order to solve this problem, the applicant provides a preparation method and application of hydrogen peroxide modified peanut shell biochar. SUMMARY

[0006] The purpose of the present application is to provide a preparation method and application of hydrogen peroxide modified peanut shell biochar, wherein the preparation method of the hydrogen peroxide modified peanut shell biochar is as follows:

[0007] 1. The peanut shell raw material is first washed with water, then dried at 80-100℃ to constant weight, crushed to pass through a 60-80 mesh sieve, and the peanut shell powder is put into excess epoxy soybean oil and reacted at 165-175℃ for 10-18h to obtain pretreated peanut shell;

[0008] 2. The pretreated peanut shell is mixed with a hydrogen peroxide solution, stirred with a magnetic stirrer at room temperature for 12-24 hours, and then placed in an oven and dried at 80-100℃ until constant weight to obtain modified peanut shell powder;

[0009] 3. The modified peanut shell powder is placed in a sealed tube furnace with nitrogen, first heated, and when the temperature reaches 500-700℃, carbonized for 1-3h, cooled to room temperature, removed from the nitrogen, and crushed to 80-100 mesh to obtain hydrogen peroxide modified peanut shell biochar;

[0010] Further, the mass concentration of the hydrogen peroxide solution is 5-10%;

[0011] Further, the mass ratio of the pretreated peanut shell to the hydrogen peroxide solution is 1:1-1:10;

[0012] Further, the flow rate of the nitrogen is 18-25mL / min;

[0013] Further, the heating rate is 10-20℃ / min;

[0014] The hydrogen peroxide modified peanut shell biochar can be applied to the adsorption of herbicides and the treatment of soil contaminated by herbicides.

[0015] Further, the hydrogen peroxide modified peanut shell biochar can be applied to the adsorption of herbicides nitrosulcotrione or atrazine.

[0016] Experimental method

[0017] Peanut shell biochar physical and chemical property determination: C, H, N, O element content is determined by element analyzer (VARO EL III); specific surface area and pore structure characteristics are determined by physical adsorption analyzer (ASAP2020M C).

[0018] Infrared analysis: The peanut shell biochar sample and potassium bromide are dried for standby, 1mg of the sample to be tested is weighed, mixed and ground with potassium bromide in a mass ratio of 1:99 in a corundum mortar, and finally pressed into a sheet in an oil press, and the test temperature is 25℃; the infrared spectrum of the biochar is scanned by a Fourier infrared spectrometer, and the wave number range is 500-4000cm -1 .

[0019] SEM analysis: The peanut shell biochar does not have conductive properties, and needs to be sprayed with a vacuum coating instrument for gold spraying treatment before observing the microstructure of the sample; the test acceleration voltage is 10.0kV, and the test distance is 6.5mm.

[0020] Herbicide adsorption dynamic experiment: take a portion of soil not contaminated by herbicide, add 0.1% of herbicide, stir evenly, divide into three groups on average, set group A: no biochar (soil), group B: add 0.1% peanut shell biochar (peanut shell biochar) according to the weight of soil, group C: add 0.1% peanut shell biochar modified by hydrogen peroxide (hydrogen peroxide grafted biochar) according to the weight of soil, three groups of treatment experiments, each group of three parallel, carry out herbicide adsorption dynamic test. Take 1g of soil sample adsorbed in different time periods, use liquid chromatograph to determine the residual amount of herbicide in each sample M e , calculate the adsorption amount according to the following formula:

[0021] Q e = M e -M0 / M

[0022] Wherein, Qe(mg / g) is the adsorption amount of peanut shell biochar (modified peanut shell biochar) to herbicide, M0, Me(mg) are the initial amount and residual amount after adsorption for a certain time of added herbicide respectively, M(g) is the mass of peanut shell biochar (modified peanut shell biochar).

[0023] Beneficial effects

[0024] The present application firstly grafts epoxy soybean oil to the surface of peanut shell to obtain pretreated peanut shell, and then modifies the peanut shell biochar by hydrogen peroxide, so that the peanut shell biochar modified by hydrogen peroxide has more oxygen-containing and nitrogen-containing functional groups and has a large cation exchange capacity; the surface of the biochar has a large number of missing electrons and a high charge density, can adsorb herbicides in the soil through hydrogen bond action and π-π electron acceptor-donor effect, form stable complex or chelate precipitate, and thus reduce the content, effectiveness and migration of the herbicides in the soil; the surface structure of the peanut shell biochar modified by hydrogen peroxide is obviously loose, some recessed channels are formed on the surface, the specific surface area and pore volume are obviously increased, and a large number of pores are present on the channel surface, which indicates that the structure of the peanut shell biochar modified by hydrogen peroxide is beneficial to increasing the specific surface area, can provide a large number of adsorption sites and space, and thus has stronger adsorption capacity; the adsorption capacity of the soil for mesotrione and atrazine is increased by 7 times and 11 times, respectively, after 0.1% of the biochar modified by hydrogen peroxide is added; after the herbicides are adsorbed, stable complex or chelate precipitate is formed, which can greatly reduce the migration and biological hazards of the herbicides; in addition, the loose pore structure of the modified peanut biochar is beneficial to accommodating more soil microorganisms, and the specific degradation capacity of certain soil microorganisms can gradually decompose the adsorbed herbicides, and finally mineralize the herbicides into carbon dioxide and water in the soil, which are absorbed by plants and then enter the natural cycle. The application of the peanut shell biochar modified by hydrogen peroxide can not only effectively solve the disposal problem of peanut shell and realize resource utilization, but also can be used as an adsorbent to realize the treatment of soil herbicide pollution and the improvement of soil, achieve the purpose of waste treatment with waste, and has good economic, social and ecological benefits, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Scanning electron microscope image of peanut shell biochar (2 μm)

[0026] Figure 2 Scanning electron microscope image of peanut shell biochar modified by hydrogen peroxide (2 μm)

[0027] Figure 3 Fourier transform infrared spectrum of peanut shell biochar modified by hydrogen peroxide

[0028] Figure 4 Adsorption dynamic test results of peanut biochar before and after modification by hydrogen peroxide for adsorbing herbicide mesotrione

[0029] Figure 5 Adsorption dynamic test results of peanut biochar before and after modification by hydrogen peroxide for adsorbing herbicide atrazine DETAILED DESCRIPTION

[0030] Example 1

[0031] The embodiment provides a preparation method of hydrogen peroxide modified peanut shell biochar.

[0032] 1. The peanut shell raw material is first washed with water, dried at 80 DEG C until constant weight, crushed through a 60 mesh sieve, and the peanut shell powder is put into excess of epoxidized soybean oil, reacted at 170 DEG C for 12h to obtain pretreated peanut shell.

[0033] 2. The pretreated peanut shell is mixed with 5% hydrogen peroxide solution at a mass ratio of 1:1, stirred by a magnetic stirrer at room temperature for 24h, then put into an oven and dried at 100 DEG C until constant weight to obtain modified peanut shell powder.

[0034] 3. The modified peanut shell powder is put into a nitrogen-inlet sealed tube furnace, the nitrogen flow rate is 18mL / min, first heated at a heating rate of 20 DEG C / min, the temperature is kept at 700 DEG C for 1h, cooled to room temperature, the nitrogen is removed, crushed through a 100 mesh sieve to obtain hydrogen peroxide modified peanut shell biochar.

[0035] Comparison of physical and chemical properties and scanning electron microscope structure of peanut shell biochar before and after modification

[0036] Control group: (unmodified) peanut shell biochar.

[0037] Experimental group: hydrogen peroxide modified peanut shell biochar prepared in example 1.

[0038] As shown in table 1, the content of oxygen and nitrogen elements of the biochar after hydrogen peroxide modification is significantly improved; compared with the unmodified, the specific surface area and pore volume are larger, which is consistent with the results of Figure 1 and Figure 2 scanning electron microscope results; Figure 1 and Figure 2 It can be known by comparison that the surface structure of the peanut shell biochar after hydrogen peroxide modification is obviously loose, some concave channels are formed on the surface, the specific surface area and pore volume are obviously increased, and a large number of pores are present on the channel surface, which indicates that the structure of the hydrogen peroxide modified peanut shell biochar is beneficial to increase the specific surface area, can provide a large number of adsorption sites and space, and thus has stronger adsorption capacity.

[0039] Table 1 Physical and chemical properties of biochar

[0040]

[0041] From Figure 3It can be seen that, compared with the unmodified peanut shell biochar, the modified peanut shell biochar has increased hydroxyl (-OH) groups, ether (C-O-C) groups, alcohol (C-OH) groups and ketone (C=O) groups, and has a large cation exchange capacity. The surface of the biochar has a large number of vacant electrons and a high charge density, which can adsorb herbicides in the soil through hydrogen bonding and π-π electron acceptor-donor effects.

[0042] Example 2

[0043] The present embodiment provides a method for preparing hydrogen peroxide modified peanut shell biochar. In the present embodiment, the peanut shell is a byproduct of oil extraction plants, and the hydrogen peroxide is purchased from Anhui Lurong Biotechnology Co., Ltd. The specific preparation steps are as follows:

[0044] 1. The peanut shell raw material is first washed with water, dried at 90°C to constant weight, and crushed to pass through an 80-mesh sieve. The peanut shell powder is placed in excess epoxy soybean oil and reacted at 175°C for 18 hours to obtain pretreated peanut shell.

[0045] 2. The pretreated peanut shell is mixed with 8% hydrogen peroxide solution at a mass ratio of 1:5, stirred with a magnetic stirrer at room temperature for 18 hours, and then placed in an oven at 100°C to dry to constant weight to obtain modified peanut shell powder.

[0046] 3. The modified peanut shell powder is placed in a nitrogen-filled closed tube furnace, the nitrogen flow rate is 22 mL / min, the temperature is first raised at a rate of 15°C / min, and when the temperature reaches 600°C, it is kept for 2 hours, then cooled to room temperature, the nitrogen is removed, and the powder is crushed to pass through an 80-mesh sieve to obtain hydrogen peroxide modified peanut shell biochar.

[0047] Example 3

[0048] The present embodiment provides a method for preparing hydrogen peroxide modified peanut shell biochar. In the present embodiment, the peanut shell is a byproduct of oil extraction plants, and the hydrogen peroxide is purchased from Anhui Lurong Biotechnology Co., Ltd. The specific preparation steps are as follows:

[0049] 1. The peanut shell raw material is first washed with water, dried at 100°C to constant weight, and crushed to pass through an 80-mesh sieve. The peanut shell powder is placed in excess epoxy soybean oil and reacted at 165°C for 10 hours to obtain pretreated peanut shell.

[0050] 2. The pretreated peanut shell was mixed with 10% hydrogen peroxide solution at a mass ratio of 1:10, stirred at room temperature for 12 hours, then placed in an oven and dried at 100°C to constant weight to obtain modified peanut shell powder;

[0051] 3. The modified peanut shell powder was placed in a sealed tube furnace with nitrogen flowing at a rate of 25 mL / min. The temperature was first raised at a rate of 10°C / min. When the temperature reached 500°C, it was maintained for 3 hours, then cooled to room temperature. The nitrogen was removed and the powder was crushed to pass through a 100 mesh sieve to obtain hydrogen peroxide modified peanut shell biochar.

[0052] Example 4

[0053] The hydrogen peroxide modified peanut shell biochar can be used to adsorb both metribuzin and atrazine herbicides.

[0054] Adsorption effect comparison test

[0055] A portion of soil not contaminated with herbicides was taken, 0.1% of the herbicide metribuzin was added, and stirred evenly. The soil was divided into three groups, with group A being untreated (soil), group B being treated with 0.1% peanut shell biochar (peanut shell biochar), and group C being treated with 0.1% hydrogen peroxide modified peanut shell biochar (hydrogen peroxide grafted biochar). Each group had three replicates, and the adsorption dynamics of metribuzin were tested.

[0056] A portion of soil not contaminated with herbicides was taken, 0.1% of the herbicide atrazine was added, and stirred evenly. The soil was divided into three groups, with group A being untreated (soil), group B being treated with 0.1% peanut shell biochar (peanut shell biochar), and group C being treated with 0.1% hydrogen peroxide modified peanut shell biochar (hydrogen peroxide grafted biochar). Each group had three replicates, and the adsorption dynamics of atrazine were tested.

[0057] Figure 4 and Figure 5 The results showed that hydrogen peroxide modified peanut biochar can significantly improve the ability of soil to adsorb herbicides. Compared with unmodified peanut biochar, the addition of 0.1% hydrogen peroxide modified biochar increased the ability of soil to adsorb metribuzin and atrazine by 7 times and 11 times, respectively.

Claims

1. A method for preparing hydrogen peroxide modified peanut shell biochar, characterized in that, The preparation method comprises the following steps: ① the raw material peanut shell is washed with water first, then dried at 80~100 ℃ to constant weight, crushed and passed through a 60~80 mesh sieve, the peanut shell powder is put into excess of epoxy soybean oil, and reaction is carried out at 165~175 ℃ for 10~18 h to obtain pretreated peanut shell; ② the pretreated peanut shell is mixed with 5~10% hydrogen peroxide solution, the mass ratio of the pretreated peanut shell to the hydrogen peroxide solution is 1:1~1:10, after stirring at room temperature for 12~24 hours, drying at 80~100 ℃ to constant weight is carried out, and modified peanut shell powder is obtained; ③ nitrogen is introduced into the modified peanut shell powder under airtight conditions, the flow rate of the nitrogen is 18~25 mL / min, temperature rising is carried out at a rate of 10~20 ℃ / min, after the temperature reaches 500~700 ℃, carbonization is maintained for 1~3 h, cooling is carried out to room temperature, the nitrogen is removed, crushing is carried out through an 80~100 mesh sieve, and hydrogen peroxide modified peanut shell biochar is obtained.

2. Use of the hydrogen peroxide modified peanut shell biochar according to claim 1, characterized in that: The hydrogen peroxide modified peanut shell biochar is used for adsorption of herbicides and treatment of soil pollution caused by herbicides. The hydrogen peroxide modified peanut shell biochar is prepared by the following method: A. the raw material peanut shell is washed with water first, then dried at 80~100 ℃ to constant weight, crushed and passed through a 60~80 mesh sieve, and pretreated peanut shell is obtained; B. the pretreated peanut shell is mixed with hydrogen peroxide solution, the mass ratio of the pretreated peanut shell to the hydrogen peroxide solution is 1:1~1:10, after stirring at room temperature for 12~24 hours, drying at 80~100 ℃ to constant weight is carried out, and modified peanut shell powder is obtained; C. nitrogen is introduced into the modified peanut shell powder under airtight conditions, the flow rate of the nitrogen is 18~25 mL / min, temperature rising is carried out at a rate of 10~20 ℃ / min, after the temperature reaches 500~700 ℃, carbonization is maintained for 1~3 h, cooling is carried out to room temperature, the nitrogen is removed, crushing is carried out through an 80~100 mesh sieve, and hydrogen peroxide modified peanut shell biochar is obtained.

3. Use of hydrogen peroxide modified peanut hull biochar according to claim 2, characterized in that, The hydrogen peroxide modified peanut shell biochar is applied to adsorption of herbicides nitrosulcotone or atrazine.

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