Application of protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon in preparation of pesticide sustained-release agent

Abstract

The invention discloses an application of protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon in preparation of a pesticide sustained-release agent, and a preparation method of the functionalized hydrothermal carbon comprises the following steps: carrying out carbonization reaction on bamboo powder and a hydrochloric acid solution by adopting a hydrothermal carbonization method, adding alkali liquor into a product obtained by the reaction, stirring, carrying out suction filtration, washing with water until filtrate is neutral, and drying to obtain the protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon. Hydrothermal bamboo charcoal is obtained; taking the hydrothermal bamboo charcoal, adding dimethylaminoethyl methacrylate, ammonium persulfate and N, N-methylene bisacrylamide to carry out ball-milling reaction, adding an acid solution into a product obtained by ball-milling, stirring, carrying out suction filtration, washing with water until filtrate is neutral, and drying filter residues to obtain a target compound. The prepared slow-release agent has high herbicide loading capacity which can reach 614mg / g, the drug loading rate reaches 38%, controllable release of pesticide molecules in dosage, time and space can be realized, and the slow-release agent has a good application prospect in the fields of agriculture and environment.

Description

Technical Field

[0001] The invention relates to an application of functionalized hydrothermal carbon, and in particular to an application of protonated poly[2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide slow-release agent. Background Art

[0002] With the rapid development of industry, the rapid increase in population, the reduction of cultivated land and the shortage of resources, the problems of environment, population, food and energy are the problems facing the world today. The use of pesticides can protect agricultural products from diseases, insects, weeds and other harmful organisms, promote the increase of agricultural production and income, alleviate the food security problems caused by the rapid increase in population, and increase the supply of biomass resources and energy. At present, the annual use of pesticides is as high as millions of tons, but the utilization rate of pesticides is low. More than 60% of pesticides enter the environment through various channels such as sedimentation, volatilization, leaching and runoff, posing a great threat to the ecological environment, and can even enter the human body through the food chain, endangering human health. Therefore, how to improve the utilization rate of pesticides and reduce the amount and frequency of pesticide use has become a key issue that needs to be solved in the fields of agriculture and environment.

[0003] Among them, pesticide slow-release agents are a new type of pesticide formulation that uses physical and chemical methods to store the active ingredients of pesticides in processed pesticide products according to the different usage methods and physical and chemical properties of pesticide varieties, and then continuously and stably releases its active ingredients under specific time, space and environmental conditions according to the needs of plants at different stages. However, existing pesticide slow-release carriers have disadvantages such as complex production processes, high prices, and low drug loading rates. Therefore, it is of great significance to develop a green, economical, and efficient pesticide slow-release carrier. Summary of the invention

[0004] Purpose of the invention: The present invention aims to provide an application of protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent, wherein the functionalized hydrothermal carbon can effectively control the release of pesticides, improve the utilization rate of pesticides, and reduce the amount and frequency of use of pesticides.

[0005] Technical solution: The application of the protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent, and the preparation method of the protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon comprises the following steps:

[0006] (1) using a hydrothermal carbonization method to carbonize bamboo powder and a hydrochloric acid solution, adding an alkali solution to the reaction product, stirring, filtering and washing with water until the filtrate is neutral, thereby obtaining hydrothermal bamboo charcoal;

[0007] (2) Take the hydrothermal bamboo charcoal, add dimethylaminoethyl methacrylate, initiator and N,N-methylenebisacrylamide to carry out ball milling reaction, add acid solution to the product obtained by ball milling, stir, filter and wash with water until the filtrate is neutral, and dry the filter residue to obtain the target compound.

[0008] The synthetic route of the above reaction is as follows:

[0009]

[0010] Furthermore, in step (1), the concentration of the bamboo powder in the hydrochloric acid solution is 0.2-0.3 g / mL, and the concentration of the hydrochloric acid is 0.5-1.0 mol / L.

[0011] Furthermore, the reaction temperature of the carbonization reaction in step (1) is 200-220° C., the carbonization time is 12-24 hours, and the alkali solution stirring time is 2-4 hours; the washing reagent used is deionized water, and the alkali solution is a sodium hydroxide solution with a concentration of 0.2-0.25 mol / L.

[0012] Furthermore, in step (2), the mass ratio of the hydrothermal carbon, dimethylaminoethyl methacrylate, initiator and N,N-methylenebisacrylamide is 8-11:18-26:1.5-2.5:0.04-0.06.

[0013] Furthermore, the ball milling reaction time in step (2) is 10-15 hours; the washing reagent used is deionized water, and the acid solution is a hydrochloric acid solution with a concentration of 0.5-1.0 mol / L.

[0014] Furthermore, the drying temperature in step (2) is 60-80°C.

[0015] Furthermore, the pesticide sustained-release agent includes protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon, the protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon serves as a pesticide carrier, and the pesticide is 2,4-D sodium.

[0016] Furthermore, the pesticide slow-release agent also includes Cl - , SO4 2- or HCO3 - Salts such as iodine are used to adjust the sustained-release rate of pesticides.

[0017] Furthermore, the pesticide sustained-release agent can also be controllably released by adjusting the pH, pH=5-7.

[0018] Principle of the invention: The present invention uses ammonium persulfate as an initiator, and prepares poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon by ball milling to initiate the graft copolymerization of dimethylaminoethyl methacrylate on the surface of hydrothermal carbon, and then obtains a protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon carrier by protonation reaction. The Zeta potential of the carrier surface of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon changes significantly with the change of solution pH, and the electrostatic and other forces between the carrier and the pesticide 2,4-D Na are affected by the change of environmental pH and ionic strength, thereby giving the pesticide sustained-release agent multiple stimulus responsiveness to pH and ionic strength. By controlling the pH or ionic strength of the environment, the controlled release of the pesticide sustained-release agent is achieved.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The preparation method of the sustained-release agent carrier adopts a ball milling method, and a free radical polymerization reaction is initiated by ball milling. The reaction does not require the use of a solvent and is green and environmentally friendly; (2) The sustained-release agent has stable performance. The sustained-release carrier prepared by the present invention exhibits a high loading capacity for anionic 2,4-D Na in a wide pH range, thereby ensuring the consistency and stability of the sustained-release agent under different environmental conditions; (3) The hydrothermal charcoal sustained-release agent has multiple responsiveness to pH and ionic strength, and can control environmental conditions to achieve sustained release; (4) The raw material used for the carrier is waste biomass, which has a wide source and low price. The method for preparing bamboo charcoal is a hydrothermal method, which is environmentally friendly and energy-saving; (5) The protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal charcoal pesticide sustained-release agent can efficiently load pesticides, and the loading rate of 2,4-D Na reaches 38%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 FTIR spectra of bamboo charcoal (HC), protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal charcoal pesticide slow-release carrier (DMAEMA-HC) and protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal charcoal pesticide slow-release agent (DMAEMA-HC-2.4-D Na);

[0021] Figure 2 is the loading capacity diagram of DMAEMA-HC for 2.4-D Na with different initial concentrations;

[0022] Figure 3 Zeta potential of DMAEMA-HC at different pH values ​​and its loading capacity for 2.4-D Na;

[0023] Figure 4] is a sustained release graph of DMAEMA-HC-2.4-D Na in different solutions; wherein, a) is a sustained release graph of DMAEMA-HC-2.4-D Na at different pH values; b) is a sustained release graph of DMAEMA-HC-2.4-D Na in a saline solution;

[0024] Figure 5 This is a graph showing the herbicidal activity study of DMAEMA-HC-2.4-D Na. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0026] Example 1

[0027] The preparation method of the protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon pesticide sustained release agent is as follows:

[0028] Weigh 40 g of bamboo powder into a 500 mL high-pressure reactor lined with polytetrafluoroethylene, add 160 mL of 1 mol / L hydrochloric acid solution, stir evenly, react at 200 ° C for 24 h, cool, filter, wash with deionized water, filter, add 400 mL of 0.2 mol / L sodium hydroxide solution and stir for 2 h, cool, filter, wash with deionized water until the filtrate reaches a stable pH value, filter, and dry at 60 ° C to obtain hydrothermal bamboo charcoal (HC);

[0029] Weigh 10g of hydrothermal bamboo charcoal, 25ml of dimethylaminoethyl methacrylate, 2g of ammonium persulfate, and 0.05g of N,N-methylenebisacrylamide, respectively, and place them in a ball milling zirconium oxide tank. After nitrogen is introduced for 10 minutes to exhaust the air in the tank, the seal is tightened, and the tank is ball milled at 500rpm for 15h. The obtained product is stirred in 0.5M hydrochloric acid (300ml) for 2h, filtered and washed with deionized water until neutral, and then the obtained sample is dried in an oven at 60℃. Protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal charcoal pesticide sustained release carrier (DMAEMA-HC) is obtained.

[0030] Example 2

[0031] The preparation method of the protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon pesticide sustained release agent is as follows:

[0032] Weigh 50 g of bamboo powder into a 500 mL high-pressure reactor lined with polytetrafluoroethylene, add 180 mL of 1 mol / L hydrochloric acid solution, stir evenly, react at 220°C for 24 h, cool, filter, wash with deionized water, filter, add 500 mL of 0.2 mol / L sodium hydroxide solution and stir for 3 h, cool, filter, wash with deionized water until the filtrate reaches a stable pH value, filter, and dry at 50°C to obtain hydrothermal bamboo charcoal (HC);

[0033] 8g of hydrothermal bamboo charcoal, 20ml of dimethylaminoethyl methacrylate, 2g of ammonium persulfate, and 0.04g of N,N-methylenebisacrylamide were weighed respectively, placed in a ball milling zirconium oxide tank, nitrogen was introduced for 10min to exhaust the air in the tank, and then the seal was tightened and ball milled at 500rpm for 12h. The obtained product was stirred in 0.5M hydrochloric acid (300ml) for 2h, filtered and washed with deionized water until neutral, and then the obtained sample was dried in an oven at 60℃. Protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal charcoal pesticide sustained release carrier (DMAEMA-HC) was obtained.

[0034] Example 3

[0035] The preparation method of the protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal carbon pesticide sustained release agent is as follows:

[0036] Weigh 45 g of bamboo powder into a 500 mL high-pressure reactor lined with polytetrafluoroethylene, add 170 mL of 1 mol / L hydrochloric acid solution, stir evenly, react at 220°C for 18 h, cool, filter, wash with deionized water, filter, add 400 mL of 0.2 mol / L sodium hydroxide solution and stir for 3 h, cool, filter, wash with deionized water until the filtrate reaches a stable pH value, filter, and dry at 60°C to obtain hydrothermal bamboo charcoal (HC);

[0037] Weigh 10g of hydrothermal bamboo charcoal, 25ml of dimethylaminoethyl methacrylate, 2g of ammonium persulfate, and 0.05g of N,N-methylenebisacrylamide, respectively, and place them in a ball milling zirconium oxide tank. After nitrogen is introduced for 10 minutes to exhaust the air in the tank, the seal is tightened, and the tank is ball milled at 500rpm for 14 hours. The obtained product is stirred in 0.5M hydrochloric acid (300ml) for 2 hours, filtered and washed with deionized water until neutral, and then the obtained sample is dried in an oven at 60℃. Protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal charcoal pesticide sustained release carrier (DMAEMA-HC) is obtained.

[0038] Structural characterization and test results analysis:

[0039] (1) FTIR

[0040] The hydrothermal bamboo charcoal and its samples before and after modification, before and after loading pesticides were characterized by infrared spectroscopy. Figure 1 . The steps of preparing the sustained-release agent by loading the hydrothermal bamboo charcoal with pesticides are as follows: 0.40 g of the hydrothermal charcoal pesticide sustained-release carrier of Example 1 is weighed into a conical flask, and 500 ml of a 500 mg / L 2,4-D Na solution is added at the same time, and the mixture is shaken in an oscillator at 100 rpm for 12 h, filtered, and dried to obtain a 2,4-D Na sustained-release agent (DMAEMA-HC-2.4-D Na). Figure 1 The middle curves represent: hydrothermal bamboo charcoal (HC), protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal charcoal pesticide sustained-release carrier (DMAEMA-HC) of Example 1, protonated poly [2-(dimethylamino) ethyl methacrylate] functionalized hydrothermal charcoal pesticide sustained-release agent (DMAEMA-HC-2.4-D Na) and 2,4-D Na.

[0041] HC at 3406, 2958, 1689, 1614 and 1384 cm -1 The peaks at 2697, 1729, and 1147 cm-1 represent the stretching vibrations of OH, aliphatic CH, C=O, and C=C, and the bending vibrations of methylene. After ball milling, the peaks changed significantly. -1 The new peaks at -NH(CH3)2 + The CH bending vibration and the stretching vibration of OC=O and CO confirmed the successful grafting of DMAEMA onto HC. -1 The peaks at represent the C=O stretching vibration and NH deformation of the amide in MBA, respectively.

[0042] After 2.4-D Na loading, at 1391cm -1 (symmetric stretching vibration of carboxylate), 1481 cm -1 (plane bending vibration of CH) and 1280cm -1 Some peaks appeared at (stretching vibration of CO in phenol), indicating that 2.4-D Na was loaded on DMAEMA-HC.

[0043] (2) Effect of initial concentration on loading capacity

[0044] 40 mg DMAEMA-HC and 50 mL 2.4-D Na solution (25, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 mg / L, T = 298 K, pH = 5) were oscillated for 12 h, and the loading amount at different initial concentrations was measured and calculated.

[0045] Figure 2 This is the effect of initial concentration on the loading of DMAEMA-HC with 2.4-D Na. As can be seen from the figure, with the increase of concentration, the loading amount of 2.4-D Na increases significantly. At 298K, with the initial concentration increasing from 25 mg / L to 1000 mg / L, the loading amount increases from 27.91 mg / g to 614.30 mg / g.

[0046] (3) Zeta potential of DMAEMA-HC at different pH values ​​and its loading capacity for 2.4-D Na

[0047] When the solution pH increases from 2 to 12, the surface charge of DMAEMA-HC changes from positive (+21.5 mV) to negative (-15 mV), and its zero point charge (pH PZC ) is around 7.6. When pH < 7.6, DMAEMA-HC presents a positive charge, and vice versa. PZC This indicates that DMAEMA-HC can load the anionic pesticide 2.4-D Na in a wide pH range. Figure 3 As shown, DMAEMA-HC exhibits a high loading capacity for anionic 2.4-D Na in a wide pH range of 4-10. This ensures the consistency and stability of the sustained-release agent under different environmental conditions, which helps to improve agricultural production efficiency and crop yields.

[0048] (4) Effects of different conditions on the sustained-release behavior of DMAEMA-HC-2.4-D Na sustained-release agent

[0049] The sustained release of DMAEMA-HC-2.4-D Na was studied. 40.0 mg DMAEMA-HC-2.4-D Na (2.4-D loading rate 34.21%) was weighed and added to a dialysis bag with a molecular weight cutoff of 8000 g / mol. The dialysis bags were placed in 250 ml beakers, and 150 ml of different pH sustained release solutions (pH = 5.0, 7.0 and 9.0, adjusted by 0.1 M NaOH and 0.1 M HCl) or salt solutions (0.01 M NaCl, 0.02 M NaCl, 0.02 M Na2SO4, pH is about 7.0) were added. The solution was shaken at 100 rpm in an oscillator at room temperature. 5 ml of supernatant was taken at a certain time interval, and 5 ml of the same solution was added at the same time. Subsequently, the filtrate was tested for the concentration of 2.4-D at a wavelength of 229.5 nm by UV-visible spectrophotometer and the cumulative release rate was calculated according to the formula.

[0050] Depend on Figure 4a) It can be seen that the cumulative release rate (CRR) of 2.4-D Na of DMAEMA-HC-2.4-D Na sustained-release agent gradually increases with time. The sustained-release rate is 11.01% to 28.63% after 178 hours under the condition of pH 5.0 to 9.0. It can be seen from the figure that the pH of the solution has a certain effect on the sustained-release ability of DMAEMA-HC-2.4-D Na.

[0051] Depend on Figure 4 b) It can be seen that the release rate of DMAEMA-HC-2.4-D Na under different ionic strengths is significantly different, and the order is: 0.02M Na2SO4>0.02M NaCl>0.01M NaCl. The cumulative release rate with Na2SO4 as the release medium reaches equilibrium after 14 hours, and the cumulative release rate with NaCl as the release medium needs 34 hours to reach equilibrium. Therefore, ionic strength significantly affects the release rate of DMAEMA-HC-2.4-D Na.

[0052] (5) Herbicidal activity

[0053] Weigh 0.40 g of the above hydrothermal charcoal pesticide sustained-release carrier into a conical flask and add 500 ml of 500 mg / L 2,4-D Na solution at the same time, shake in an oscillator at 100 rpm for 12 h, filter and dry to obtain a 2,4-D Na sustained-release agent (DMAEMA-HC-2.4-D Na).

[0054] Prepare five groups of culture dishes with a diameter of 9 cm, add 10 ml of test solution to each (a: deionized water, b: deionized + DMAEMA-HC, c: 0.01M NaCl solution, d: 100ppm 2.4-D Na solution, e: 0.01M NaCl solution + DMAEMA-HC-2.4-D Na, where the amount of 2.4-D Na in group e is the same as that in group d, and the amount of sustained-release agent carrier in group b and group e is the same), then put a layer of filter paper in the culture dish, and then put 20 rapeseed seeds on each filter paper. Grow in an incubator with a temperature of 26°C, a humidity of 85%, and a light intensity of (3000lx). The first three days are completely dark, and the next five days are alternating day and night (12 / 12). Measure the root length and stem length of rapeseed under different conditions, and compare the fresh weight and dry weight of the seeds.

[0055] like Figure 5As shown in the figure, compared with the pure water control group, the 0.01M NaCl solution had no side effects on the growth of rapeseed and could significantly promote the root and stem growth of rapeseed. In addition, DMAEMA-HC had no significant effect on the growth of rapeseed, indicating that DMAEMA-HC has good biosafety and is suitable for use as a pesticide carrier. From the growth of rapeseed, the root length, fresh weight and dry weight of rapeseed after applying DMAEMA-HC-2.4-D Na in 0.01M NaCl medium were lower than those after applying 2.4-D sodium aqueous solution with the same dose and concentration, indicating that DMAEMA-HC-2.4-D Na has higher biological activity on rapeseed than 2.4-D sodium.

Claims

1. Application of protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of pesticide sustained-release agent, characterized in that: The preparation method of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon comprises the following steps: (1) using a hydrothermal carbonization method to carbonize bamboo powder and a hydrochloric acid solution, adding an alkali solution to the reaction product, stirring, filtering and washing with water until the filtrate is neutral, thereby obtaining hydrothermal bamboo charcoal; (2) Take the hydrothermal bamboo charcoal, add dimethylaminoethyl methacrylate, initiator and N,N-methylenebisacrylamide to carry out ball milling reaction, add acid solution to the product obtained by ball milling, stir, filter and wash with water until the filtrate is neutral, and dry the filter residue to obtain the target compound.

2. The use of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent according to claim 1, characterized in that: The concentration of the bamboo powder in the hydrochloric acid solution in step (1) is 0.2-0.3 g / mL, and the concentration of the hydrochloric acid solution is 0.5-1.0 mol / L.

3. The use of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent according to claim 1, characterized in that: The reaction temperature of the carbonization reaction in step (1) is 200-220° C., the carbonization time is 12-24 hours, and the alkali solution stirring time is 2-4 hours.

4. The use of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent according to claim 1, characterized in that: The alkali solution in step (1) is a sodium hydroxide solution with a concentration of 0.2-0.25 mol / L.

5. The use of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent according to claim 1, characterized in that: The mass ratio of the hydrothermal bamboo charcoal, dimethylaminoethyl methacrylate, ammonium persulfate and N,N-methylenebisacrylamide in step (2) is 8-11:18-26:1.5-2.5:0.04-0.

06.

6. The use of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent according to claim 1, characterized in that: The ball milling reaction time in step (2) is 10-15h.

7. The use of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent according to claim 1, characterized in that: The acid solution in step (2) is a hydrochloric acid solution with a concentration of 0.5-1.0 mol / L.

8. The use of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent according to claim 1, characterized in that: The drying temperature in step (2) is 60-80°C.

9. The use of the protonated poly [2-(dimethylamino)ethyl methacrylate] functionalized hydrothermal carbon in the preparation of a pesticide sustained-release agent according to claim 1, characterized in that: The pesticide slow-release agent also includes Cl - , SO4 2- or HCO3 - The pesticide is 2,4-D sodium.

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