Preparation and Application Method of Amino-Containing Straw Cellulose CuFe Composite Material

Abstract

This invention belongs to the field of straw resource utilization technology, and discloses a method for preparing and applying an amino-containing straw cellulose CuFe composite material. By pretreating straw with ammoniation at low temperature to increase the proportion of nitrogen-containing active functional groups and improve the adsorption capacity of the straw material, a spherical amino-containing straw cellulose CuFe composite material is synthesized using a one-step hydrothermal method. This spherical amino-containing straw cellulose CuFe composite material can be used to activate persulfate to degrade pesticides and other organic pollutants in soil or farmland runoff, exhibiting the characteristic of simultaneous adsorption and degradation of organic pollutants, thus achieving in-situ degradation of pesticide residues in soil.

Description

Technical Field

[0001] This invention belongs to the field of straw resource utilization technology, specifically relating to the preparation and application method of an amino-containing straw cellulose CuFe composite material. Background Technology

[0002] The utilization of straw resources includes straw returning to the field as fertilizer, straw fermentation for feed, straw material production, straw energy production, and straw substrate production. Improving the level of straw resource utilization has become an important way to efficiently solve the environmental pollution problems caused by straw resources. As a biomass resource, straw contains a large number of carbon-containing functional groups, such as the hydroxyl groups in straw cellulose and the aromatic functional groups in straw lignin. These functional groups can serve as the main active sites for functional polymer materials, such as nano-sized cellulose powder and lignin-based coatings. In addition, straw is also used to prepare biochar as a functional material for environmental pollution control.

[0003] CuFe, as a bimetallic catalyst, can activate persulfate to degrade organic pollutants under certain conditions. Patent (CN201710279119.0) discloses a method for degrading organic wastewater using CuFeO2 material coupled with persulfate under visible light catalysis. This method utilizes CuFeO2 material to degrade organic pollutants by coupling with persulfate under visible light (wavelength greater than 420nm). This method has advantages such as selectivity, low requirements for wastewater quality, and good removal efficiency. However, CuFeO2 material also has some drawbacks, such as easy aggregation in aqueous phases, difficulty in recovery, and poor recycling efficiency, thus limiting its widespread application. Improving the recovery rate or recycling efficiency of the material while reducing production costs is an important way to promote the widespread application of bimetallic materials. Patent (CN202210558254.X) discloses a biochar-supported bimetallic composite catalytic material, its preparation method, and its application. This material utilizes biochar to support spinel-type copper-iron ferrite (CuFe-2O-4) to prepare a catalytically active composite catalytic material. This not only weakens the magnetism of the spinel-type copper-iron ferrite but also alleviates its tendency to agglomerate, thus improving the catalytic activity and stability of the composite catalytic material. However, this material requires high-temperature preparation, consuming considerable energy. Furthermore, the catalytically active center, the spinel-type copper-iron ferrite, is only supported on the surface of the biochar and easily detaches from the support, causing the loss of the active center and weakening the catalytic degradation performance of the composite material. Therefore, the biochar-supported spinel-type copper-iron ferrite (CuFe-2O-4) composite catalytic material is difficult to promote and apply in ordinary farmland.

[0004] Furthermore, the widespread use of pesticides has led to common pesticide residue pollution in farmland soils. To reduce pesticide residues in the soil and mitigate the risk of them entering adjacent water bodies or groundwater, in addition to continuing to reduce pesticide use, it is necessary to adopt practical agronomic measures to achieve in-situ degradation of pesticide residues in the soil. This invention, based on the inherent chemical structure of straw materials, increases the proportion of nitrogen-containing active functional groups in straw through ammoniation pretreatment, thereby enhancing the material's adsorption capacity for pesticides and other organic compounds. Simultaneously, a one-step hydrothermal method is used to synthesize spherical amino-containing straw cellulose CuFe composite materials. This material can be used to activate persulfate to degrade pesticide organic pollutants in soil or farmland runoff, featuring simultaneous adsorption and degradation, and recyclability. It can reduce pesticide residues in soil and water environments, lower the risk of pesticide pollution in soil and water, and simultaneously provide organic nutrients for soil microorganisms, achieving in-situ degradation of pesticide residues in the soil. Summary of the Invention

[0005] This invention employs a low-temperature dissolution pretreatment technique to obtain straw cellulose material with a porous structure and containing amino functional groups. Then, a pre-activated solution containing Cu and Fe ions of inorganic salt is added, and an amino-containing straw cellulose CuFe composite material is prepared through a one-step hydrothermal synthesis method. This material has certain adsorption and degradation capabilities and can be recycled. It can effectively degrade organic pollutants such as pesticides in farmland water and soil environments, and alleviate the risk of pesticide residue pollution in farmland environments.

[0006] The technical solution of the present invention:

[0007] A method for preparing an amino-containing straw cellulose CuFe composite material, comprising the following steps:

[0008] (1) Pretreatment of straw ammoniation: Take dry and crushed straw (10-100 mesh) and put it into a frozen plastic box. Add 10-20 times the weight of straw in ultrapure water, then add 0.1-5% of straw weight in ammonia, 5%-20% of straw weight in urea, and 0.1-1% of straw weight in ZnCl2. After stirring and dissolving thoroughly, seal the box and sonicate it at room temperature for 5-10 minutes. Then put it into a low temperature freezer and react it fully at -20℃ to -5℃ for 1-7 days. Take out the straw material, thaw it naturally, and react it in a constant temperature water bath at 40℃-50℃ for 3-10 hours. After the reaction is completed, wash it with pure water 3-5 times. Dry the pretreated straw material at 60℃-70℃ and seal it for later use.

[0009] (2) Preparation of straw cellulose CuFe composite material: Copper nitrate trihydrate, ferric nitrate nonahydrate, zinc nitrate, polyethylene glycol and silicon dioxide were mixed, and pure water with a mass of 10-50 times that of copper nitrate trihydrate was added. After thorough stirring, the mixture was ultrasonically treated for 10-20 min to obtain an activation solution. The activation solution was added to the pretreated straw material obtained in step (1), wherein the mass of copper nitrate trihydrate in the activation solution accounted for 40%-80% of the mass of the straw material. An appropriate amount of pure water was added to control the mass ratio of the reaction solution to the pretreated straw material at (10-20):1. The straw material was ultrasonicated at 40-50℃ for 20-30 minutes. 2-20% of the pretreated straw material's mass of sodium hydroxide solid was added, and the mixture was quickly stirred, sealed, and placed in a forced-air drying oven. The mixture was reacted at 100-150℃ for 5-20 hours. After cooling to room temperature, the material was washed twice with pure water, twice with anhydrous ethanol, and three times with pure water. The washed material was then placed in a forced-air drying oven at 60-80℃ for 10-15 hours with the airflow controlled at 50%-60%. This yielded an amino-containing straw cellulose CuFe composite material, which was then stored in a sealed bag for later use.

[0010] The straw includes corn straw, rice straw, wheat straw, cotton straw, etc.

[0011] The molar ratio of copper nitrate trihydrate and ferric nitrate nonahydrate is 1:(1-5), the amount of zinc nitrate is 0.1%-0.5% of the mass of the pretreated straw material, the amount of polyethylene glycol is 5%-20% of the mass of the pretreated straw material, and the amount of silica is 0.1%-2% of the mass of the pretreated straw material.

[0012] An application method for an amino-containing straw cellulose CuFe composite material includes the following steps:

[0013] Select a flat farmland plot and dig trenches 30-40cm deep around the plot. Add amino-containing straw cellulose CuFe composite material and persulfate solids. Fill the trenches with the excavated soil and level the surface. Compact the surface by vibration. The trenches should be 20-40cm wide. Apply 20-40kg of composite material per 1m of trench length. This can effectively degrade residual organic pollutants in the soil.

[0014] The persulfate includes sodium persulfate, ammonium persulfate, potassium persulfate, etc., and its dosage is 1%-2% of the amino-containing straw cellulose CuFe composite material.

[0015] The types of organic pollutants in the soil include atrazine, acetochlor, trifluralin herbicide, imidacloprid, acetamiprid, thiamethoxam insecticide, thiabendazole, tebuconazole, and carbendazim fungicide.

[0016] The beneficial effects of this invention are as follows: This invention prepares an amino-containing straw cellulose CuFe composite material, which is low in cost, highly active, stable, recyclable, and environmentally friendly. It can achieve the purpose of adsorbing and degrading organic pollutants such as pesticides simultaneously, and can be applied to the prevention and control of organic pollution from pesticides in farmland water and soil, thereby alleviating the pollution caused by pesticide residues in the farmland environment. Attached Figure Description

[0017] Figure 1 It refers to the nitrogen content of straw materials under different pretreatments.

[0018] Figure 2 This is a microscopic morphology diagram of the composite material.

[0019] Figure 3 These are the X-ray diffraction patterns of the composite material before and after the reaction.

[0020] Figure 4 This is the effect of recycling composite materials.

[0021] Figure 5 It is the effect of composite materials on degrading atrazine in runoff. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0023] Example 1: Effect of straw ammoniation pretreatment on the adsorption performance of the material

[0024] Take 10g of dried and pulverized straw (20 mesh) and add it to a frozen plastic box. Add 100mL of pure water, then add 0.2g of ammonia, 1.5g of urea, and 0.05g of zinc chloride in sequence. Set up a control experiment, i.e., add 0.2g of ammonia alone, 1.5g of urea alone, 0.05g of zinc chloride alone, 0.2g of ammonia and 1.5g of urea, 0.2g of ammonia and 0.05g of zinc chloride, and 1.5g of urea and 0.05g of zinc chloride. After thoroughly stirring and dissolving, sonicate at room temperature for 5 minutes, then place in a low-temperature freezer and react fully at -10℃ for 7 days. Take out the straw material, thaw it naturally, and react it in a 40℃ constant temperature water bath for 5 hours to end the reaction. Take out the straw material, wash it 5 times with pure water, and dry it at 60℃ for later use. Figure 1As shown, compared with single ammonia treatment, the nitrogen content of pretreated straw increased by 40.1% when ammonia and zinc chloride were treated simultaneously; compared with single urea treatment, the nitrogen content of pretreated straw increased by 26.7% when urea and zinc chloride were treated simultaneously. Therefore, the addition of zinc chloride helps to increase the nitrogen content of pretreated straw. Compared with single ammonia treatment, the addition of urea increased the nitrogen content of straw pretreated with ammonia and urea by 80%, and the proportion of nitrogen in pretreated straw with ammonia, urea, and zinc chloride was the highest, at 2.9%. Overall, the addition of either urea or zinc chloride helps to increase the nitrogen content of straw and improve the ammoniation degree of straw. 0.1 g of straw material with different pretreatments was taken sequentially and added to a reaction flask. 40 mL of a 10 mg / L acetochlor solution was poured in, and the adsorption reaction was carried out at 25℃. After 24 h, samples were taken to test the concentration of acetochlor in the reaction solution, and the adsorption capacity (L / kg) of acetochlor by different pretreated straw materials was analyzed. The results showed that the adsorption partition coefficients of acetochlor for raw straw and straw material pretreated with ammonia, urea, or zinc chloride alone were 56 L / kg, 67 L / kg, 61 L / kg, and 59 L / kg, respectively, all lower than those for straw material pretreated with a mixture of two or three of these agents. Meanwhile, the straw material pretreated with a mixture of ammonia, urea, and zinc chloride showed the highest adsorption capacity for acetochlor at 124 L / kg, which was greater than the adsorption capacity of straw material pretreated with ammonia and urea, ammonia and zinc chloride, or urea and zinc chloride. The results of the correlation analysis showed that the adsorption capacity of pretreated straw materials for acetochlor was positively correlated with the nitrogen content of the materials (P<0.01). Therefore, the higher the degree of ammoniation pretreatment of straw, the greater the adsorption capacity of the materials for acetochlor.

[0025] Example 2: Structural characteristics of amino-containing straw cellulose materials

[0026] After treating the straw using the ammoniation pretreatment method of Example 1, 4.5g of copper nitrate trihydrate, 7.3g of ferric nitrate nonahydrate, 0.016g of zinc nitrate, 1.0g of polyethylene glycol, and 0.08g of silicon dioxide were sequentially added to 100mL of pure water and fully dissolved. The mixture was then sonicated for 10min to obtain an activated solution. This solution was slowly poured into a polytetrafluoroethylene hydrothermal reactor containing 8g of pretreated straw material. The reactor was sonicated at 40℃ for 20min, and 5.0g of sodium hydroxide solid was added. After rapid stirring, the reactor was sealed and placed in a forced-air drying oven. The reaction was carried out at 100℃ for 12h. After cooling to room temperature, the material was washed twice with pure water, twice with anhydrous ethanol, and three times with pure water. The washed material was then dried in an 80℃ forced-air drying oven for 10h with the airflow controlled at 60%. This yielded an amino-containing straw cellulose CuFe composite material, which was then stored in a sealed bag for later use. Scanning electron microscopy revealed that the composite material contained spherical CuFe straw fiber material (see attached image). Figure 2 X-ray diffraction analysis shows (see attached) Figure 3 Compared with the original straw, the strength of the crystalline region of the straw composite material near 2θ=22.8° is weakened. This is mainly because CuFe penetrates into the crystalline region and forms hydrogen bonds with functional groups such as OH on the surface of the straw crystalline region, which destroys the crystalline structure of the straw.

[0027] Example 3: Effect of recycling straw cellulose CuFe composite materials prepared at different reaction temperatures

[0028] Using the methods of straw pretreatment in Example 1 and composite material preparation in Example 2, the hydrothermal reaction temperature was varied, set at 100℃, 120℃, 150℃, and 180℃. Copper nitrate trihydrate (4.5g), ferric nitrate nonahydrate (7.3g), zinc nitrate (0.016g), polyethylene glycol (1.0g), and silicon dioxide (0.08g) were added to 100mL of pure water, dissolved completely, and ultrasonically treated for 10min to obtain an activated solution. This solution was slowly poured into a polytetrafluoroethylene hydrothermal reactor containing 8g of pretreated straw material, and the reaction was carried out at 40℃. The mixture was sonicated for 20 minutes, then 5.0g of solid sodium hydroxide was added. After rapid stirring, the lid was tightened, and the reactor was placed in a forced-air drying oven. The reaction was carried out at 100℃, 120℃, 150℃, and 180℃ for 12 hours respectively. After cooling to room temperature, the mixture was washed twice with pure water, twice with anhydrous ethanol, and three times with pure water. The washed material was then placed in an 80℃ forced-air drying oven for 10 hours with the airflow rate controlled at 60%. This yielded amino-containing straw cellulose CuFe composite materials prepared under different reaction temperature conditions. The composite materials were then stored in sealed bags for later use.

[0029] Runoff containing imidacloprid insecticide was collected from farmland. The initial concentration of imidacloprid in the runoff was 4 mg / L. For each treatment, 50 mL of runoff was collected, and 0.1 g of the composite material and 5 mg of sodium persulfate were added. The mixture was reacted at room temperature for 12 h, followed by solid-liquid separation by filtration. The same amount of fresh runoff solution and sodium persulfate were added again, and the reaction was continued at room temperature for another 12 h. This process was repeated 10 times, with 3 parallel replicates for each material. The concentration of imidacloprid in the runoff was measured, and the adsorption and degradation removal rates of imidacloprid by the composite material were calculated. (See attached...) Figure 4 After 10 cycles of the reaction, the straw composite material obtained at four hydrothermal reaction temperatures of 100℃, 120℃, 150℃ and 180℃ showed adsorption and degradation removal rates of imidacloprid in runoff water of 57%, 63%, 72% and 69%, respectively. This indicates that at temperatures below 150℃, the increase in hydrothermal reaction temperature is beneficial to improving the adsorption and degradation capacity of the composite material for pesticides. At the same time, the composite material has a certain degree of recyclability.

[0030] Example 4: Application of straw cellulose CuFe composite material in the degradation of atrazine pesticides in runoff.

[0031] The straw cellulose CuFe composite material prepared under reaction conditions of 120℃ and 150℃ as described in Example 3 was used for agricultural application trials. A 2m deep trench (40cm deep) and 10cm wide were dug around the perimeter of a farmland. 40kg each of the two spherical amino-containing straw cellulose CuFe composite materials prepared under reaction conditions of 120℃ and 150℃ were added, along with 0.5kg of sodium persulfate. The trenches were then filled with soil. Three parallel trials were conducted. The initial concentration of atrazine herbicide in the soil was 10mg / kg. The concentration of atrazine in the runoff was monitored periodically. The pesticide removal rate (%) was calculated by comparing the initial and measured concentrations. (See Appendix...) Figure 5 The results showed that the composite material synthesized at 120℃ and 150℃, under the action of sodium persulfate, could remove more than 60% of atrazine from the runoff water after four monitoring tests.

Claims

1. A method for preparing amino-containing straw cellulose CuFe composite material for activating persulfate to degrade pesticide organic pollutants in soil, characterized in that, The steps are as follows: (1) straw ammoniation pretreatment: take dry and well-crushed 10-100 mesh straw, put it into a frozen plastic box, add 10-20 times of ultrapure water of the straw mass, then add 0.1-5% ammonia water of the straw mass, 5%-20% urea of the straw mass, and 0.1-1% ZnCl2 of the straw mass in sequence, fully stir and dissolve, seal, ultrasonic for 5-10 min at room temperature, then put it into a low-temperature refrigerator, fully react for 1-7 d under the condition of-20 o C to-5 o C, take out the straw material, naturally thaw, react for 3-10 h in a 40 o C-50 o C constant-temperature water bath, end the reaction, wash with pure water for 3-5 times, dry the pretreated straw material under the condition of 60 o C-70 o C, and seal for standby use; (2) Preparation of straw cellulose CuFe composite material: mix copper nitrate trihydrate, iron nitrate nonahydrate, zinc nitrate, polyethylene glycol and silicon dioxide, add pure water 10-50 times the mass of copper nitrate trihydrate, fully stir, then ultrasonic treat for 10-20 min to obtain an activation solution; add the activation solution to the pretreated straw material obtained in step (1), the mass of copper nitrate trihydrate in the activation solution accounts for 40%-80% of the mass of the straw material, supplement with appropriate amount of pure water, control the mass ratio of the reaction solution to the pretreated straw material at (10-20):1, ultrasonic treat for 20-30 min under 40-50 o C, add sodium hydroxide solid 2-20% of the mass of the pretreated straw material, fast stir, then seal, put into a blast drying oven, react for 5-20 h under 100-150 o C, after cooling to room temperature, sequentially wash with pure water twice, anhydrous ethanol twice, and pure water three times, put the washed material into a 60-80 o C blast drying oven to dry for 10-15 h, control the wind speed at 50%-60%, obtain the straw cellulose CuFe composite material containing amino groups, put into a sealed bag for storage for standby use.

2. The production method according to claim 1, characterized by, The straw includes corn straw, rice straw, wheat straw, and cotton straw.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the copper nitrate trihydrate and the iron nitrate nonahydrate is 1:(1-5), the amount of zinc nitrate is 0.1%-0.5% of the mass of the pretreated straw material, the amount of polyethylene glycol is 5%-20% of the mass of the pretreated straw material, and the amount of silicon dioxide is 0.1%-2% of the mass of the pretreated straw material.

4. The use of the CuFe composite material containing amino-straw cellulose prepared by the method according to any one of claims 1 to 3, characterized in that, The steps are as follows: A flat farmland plot is selected, a 30-40 cm deep ditch is dug around the plot, the amino-containing straw cellulose CuFe composite material and the persulfate solid are added, the ditch is filled and flattened with the dug soil, the surface is compacted by oscillation, the width of the ditch is 20-40 cm, and the amount of the composite material added is 20-40 kg per 1 m length of the ditch, which can effectively degrade the residual pesticide organic pollutants in the soil.

5. The method of claim 4, wherein the compound is administered in an amount of about 0.1 to 10 mg / kg. The persulfate includes sodium persulfate, ammonium persulfate, and potassium persulfate, and the amount is 1%-2% of the amino-containing straw cellulose CuFe composite material.

6. The use according to claim 4, characterized in that, The types of the organic pollutants in the soil include atrazine, acetochlor, trifluralin herbicide, imidacloprid, acetamiprid, thiamethoxam insecticide, thiabendazole, and carbendazim fungicide.

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