Melamine formaldehyde porous polymer, its preparation method and application

Abstract

The application discloses melamine formaldehyde porous polymer and a preparation method and application thereof, and belongs to the technical field of environmental pollution treatment. The melamine formaldehyde porous polymer provided by the application has adsorption effect on forchlorfenuron, maleic anhydride, tebuconazole, nithiazine, thiacloprid and paclobutrazol pesticides, and no report on the adsorption research of the melamine formaldehyde porous polymer adsorption material on the related pesticides is available. The melamine formaldehyde porous polymer has a large adsorption capacity on forchlorfenuron, maleic anhydride and tebuconazole pesticides, and the adsorption capacity of forchlorfenuron can reach 231.4 mg / g. The material is simple to prepare, low in price and has strong application performance.

Description

Technical Field

[0001] This invention relates to the field of environmental pollution control technology, and in particular to a melamine-formaldehyde porous polymer, its preparation method, and its application. Background Technology

[0002] After pesticides are applied, some adhere to the plants or seep into the plant, contaminating grains, vegetables, and fruits. Others are released into the soil (sometimes applied directly) or evaporate and disperse into the air, or flow into rivers and lakes with rainwater and farmland drainage, polluting water bodies and aquatic life. Pesticide residues in agricultural products contaminate livestock products through feed. Ultimately, pesticide residues enter the human body through the atmosphere, water, soil, and food, causing various chronic or acute diseases.

[0003] Pesticide pollution is a serious problem in water bodies, stemming from several sources. Some pesticides are applied directly to water bodies; others enter the atmosphere and are carried into water bodies by rainwater; pesticides adhering to plants or soil are washed away or dissolved by water; and industrial wastewater from pesticide production or domestic sewage containing pesticides also pollutes water bodies. Therefore, researching reliable methods for treating pesticide pollution in water bodies aligns with the goals of sustainable development and has significant socio-economic value.

[0004] Currently, the structures of adsorbent materials are diverse. Adsorbent materials can take the form of powders, granules, fibers, membranes, etc., and different structural forms are selected according to different application requirements. They are applied in various economic fields, such as the treatment and resource recovery of various wastes, including waste gas, wastewater, and solid waste. These applicable adsorbent materials often have the following characteristics: 1. Selectivity: Adsorbent materials can selectively adsorb certain substances, while having no adsorption effect on other substances. 2. High efficiency: Adsorbent materials have high adsorption efficiency and large adsorption capacity. In recent years, research on pesticide pollutant adsorption has developed rapidly. For example, Yoon et al. studied the adsorption performance and mechanism of the pesticide cymoxanil on grape pomace biochar. The maximum adsorption capacity of the biochar produced at 350℃ at pH 7 was 161 mg / g. Liu Yongpan et al. prepared functionalized material Zr@AC by loading zirconium metal onto activated carbon and investigated the removal effect of Zr@AC on atrazine in water. The maximum adsorption capacity was 93.8 mg / g. Elhussein et al. prepared CeO2 nanofibers using Ce(1,3,5-BTC)(H2O)6 (Ce-BTC) metal-organic framework as raw material and studied the affinity of CeO2 for 2,4-dichlorophenoxyacetic acid (2,4-D). The maximum adsorption capacities for 2,4-D at 298, 308 and 318 K were 86.16, 95.78 and 84.29 mg / g, respectively. However, due to the large variety of pesticides, many pesticide pollutants still lack effective adsorption solutions. Therefore, the development of new adsorption materials for pesticides is both practical and in demand by the market. Summary of the Invention

[0005] The purpose of this invention is to provide a melamine-formaldehyde porous polymer, its preparation method, and its application, in order to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides a melamine-formaldehyde porous polymer, which is prepared by a pressure reaction of melamine and paraformaldehyde.

[0008] The present invention also provides a method for preparing the melamine-formaldehyde porous polymer, wherein melamine and paraformaldehyde are dissolved in a solvent and reacted under certain pressure, temperature and time to prepare crude melamine-formaldehyde porous polymer, and then washed and dried to obtain melamine-formaldehyde porous polymer.

[0009] Preferably, the pressure is 1.5-3.0 MPa.

[0010] Preferably, the pressure is 1.5 MPa.

[0011] Preferably, the temperature is 130-180°C.

[0012] Preferably, the temperature is 130°C.

[0013] Preferably, the time is 8-48 hours.

[0014] Preferably, the time is 24 hours.

[0015] The present invention also provides the application of the prepared melamine-formaldehyde porous polymer in the adsorption and treatment of pesticide pollution.

[0016] Preferably, the pesticide includes chlorpyrifos, dimethomorph, tebuconazole, thiamethoxam, paclobutrazol and / or thiamethoxam.

[0017] This invention provides a melamine-formaldehyde porous polymer with the following beneficial effects:

[0018] 1. It has adsorption properties for pesticides such as chlorpyrifos, dimethomorph, tebuconazole, thiamethoxam, thiamethoxam, and paclobutrazol. Currently, there are no reports on the adsorption of related pesticides by melamine-formaldehyde porous polymers.

[0019] 2. It has a large adsorption capacity for pesticides such as chlorpyrifos, dimethomorph, and tebuconazole. The adsorption capacity for chlorpyrifos pesticide can reach 231.4 mg / g.

[0020] 3. By applying pressure, melamine-formaldehyde porous polymers with similar quality to those obtained by methods at higher temperatures (170℃ and longer time, 3 days) can be obtained at a lower temperature (130℃) and in a shorter time (1 day). Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The changes in UV spectra before and after adsorption of chlorpyrifos by the melamine-formaldehyde porous polymer;

[0023] Figure 2 The changes in infrared spectra of melamine-formaldehyde porous polymer before and after adsorption of chlorpyrifos (mPMF is melamine-formaldehyde porous polymer, CPPU is chlorpyrifos);

[0024] Figure 3 (a) SEM image of melamine-formaldehyde porous polymer before adsorption, (b) SEM image of melamine-formaldehyde porous polymer after adsorption of chlorpyrifos, (c) Energy dispersive X-ray spectroscopy (EDS) image of melamine-formaldehyde porous polymer before adsorption, and (d) Energy dispersive X-ray spectroscopy (EDS) image of melamine-formaldehyde porous polymer after adsorption of chlorpyrifos. Detailed Implementation

[0025] This invention provides the following solution:

[0026] This invention provides a melamine-formaldehyde porous polymer, which is prepared by a pressure reaction of melamine and paraformaldehyde.

[0027] The present invention also provides a method for preparing the melamine-formaldehyde porous polymer, wherein melamine and paraformaldehyde are dissolved in a solvent and reacted under certain pressure, temperature and time to prepare crude melamine-formaldehyde porous polymer, and then washed and dried to obtain melamine-formaldehyde porous polymer.

[0028] Preferably, the pressure is 1.5-3.0 MPa.

[0029] Preferably, the pressure is 1.5 MPa.

[0030] Preferably, the temperature is 130-180°C.

[0031] Preferably, the temperature is 130°C.

[0032] Preferably, the time is 8-48 hours.

[0033] Preferably, the time is 24 hours.

[0034] The present invention also provides a method for treating pesticide pollution, wherein the melamine-formaldehyde porous polymer prepared as described above is used to adsorb pesticides.

[0035] Preferably, the pesticide includes chlorpyrifos, dimethomorph, tebuconazole, thiamethoxam, paclobutrazol and / or thiamethoxam.

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0037] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0038] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0039] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0040] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0041] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0042] Example 1

[0043] Screening of preparation conditions for melamine-formaldehyde porous polymers:

[0044] The general conditions are:

[0045] (1) Mix 2.25 equivalents of paraformaldehyde, 1 equivalent of melamine and 10 volumes (solid-liquid ratio 10, which means 1g of melamine, then 10mL of solvent needs to be added) of DMSO and heat to dissolve. Then add it to a high pressure vessel and react for a certain time under certain temperature and pressure. After cooling to room temperature, filter to obtain crude porous polymer.

[0046] (2) The porous polymer crude product was crushed and then soaked, washed and filtered in acetone, dichloromethane, methanol and tetrahydrofuran in a mass-volume ratio of 1:10 (based on the mass of melamine, that is, 10 mL of solvent needs to be added for 1 g of melamine). After washing and filtering three times with each solvent, the product was dried under vacuum at 120°C to obtain a melamine-formaldehyde porous polymer sample with high specific surface area.

[0047] Experiment 1: Pressure Comparison in the Preparation of Melamine-Formaldehyde Porous Polymers

[0048] The temperature was 130℃, the time was 1 day, and nitrogen was used to pressurize the reactor to the predetermined pressure. Pressure fluctuations during the reaction process were not included in the data. Other conditions were the same as general conditions. The results of material preparation under different pressures were examined, as shown in Table 1.

[0049] Table 1 Pressure screening for the preparation of melamine-formaldehyde porous polymers

[0050] Pressure (MPa) <![CDATA[Specific surface area (m 2 / g)]]> 0.0 326 0.5 511 1.0 697 1.5 872 2.0 870 2.5 877 3.0 868

[0051] As shown in Table 1, under the same conditions, the specific surface area reaches its optimum when the pressure reaches 1.5 MPa, and the specific surface area is significantly better than that of the unpressurized sample.

[0052] Experiment 2: Temperature Screening for the Preparation of Melamine-Formaldehyde Porous Polymer

[0053] The reaction time was one day. The reactor was pressurized to 1.5 MPa using nitrogen. Pressure fluctuations during the reaction were not included in the data. Other conditions were the same as general conditions. The material preparation results at different temperatures were examined, as shown in Table 2.

[0054] Table 2 Screening of preparation temperature for melamine-formaldehyde porous polymer

[0055] Reaction temperature (°C) <![CDATA[Specific surface area (m 2 / g)]]> 90 685 100 712 110 786 120 821 130 872 140 870 150 868 160 873 170 866 180 869

[0056] As shown in Table 2, the specific surface area reaches its optimum when the reaction temperature reaches 130℃, and further increasing the temperature has little effect on the specific surface area.

[0057] Experiment 3: Screening of preparation time for melamine-formaldehyde porous polymer

[0058] The temperature was 130℃, and the reactor was pressurized to 1.5 MPa using nitrogen. Pressure fluctuations during the reaction process were not included in the data. Other conditions were the same as general conditions. The material preparation results at different times were examined, as shown in Table 3.

[0059] Table 3 Screening of preparation time for melamine-formaldehyde porous polymer

[0060] Reaction time (h) <![CDATA[Specific surface area (m 2 / g)]]> 8 548 16 817 24 872 32 859 40 868 48 875

[0061] As shown in Table 3, the maximum specific surface area is reached when the reaction time is 24 hours, and extending the time does not significantly improve the specific surface area.

[0062] By applying pressure, melamine-formaldehyde porous polymers of similar quality to those obtained by conventional methods can be obtained at a lower temperature (130℃) and in a shorter time (one day). (Reference: W. Lu, PS Julian, D. Yuan, R. Krishna, Z. Wei, HC Zhou, Angew. Chem., Int. Ed. 2012, 51, 7480. Preparation conditions: no pressure – natural pressure in a hydrothermal autoclave, 170℃, 3 days, specific surface area 857 m²). 2 / g).

[0063] Example 2

[0064] Material preparation method: 2.25 equivalents of paraformaldehyde, 1 equivalent of melamine, and 10 volumes (solid-liquid ratio 10, i.e., 10 mL of solvent is needed for 1 g of melamine) of DMSO were mixed and dissolved by heating. The mixture was then added to an autoclave and reacted at 130℃ and 1.5 MPa for 1 day (24 h). After cooling to room temperature, the mixture was filtered to obtain a crude porous polymer. The crude porous polymer was crushed and sequentially soaked, washed, and filtered with acetone, dichloromethane, methanol, and tetrahydrofuran in a mass-to-volume ratio of 1:10 (based on the mass of melamine, i.e., 10 mL of solvent is needed for 1 g of melamine). Each solvent was used for washing and filtration three times. The mixture was then vacuum dried at 120℃ to obtain a melamine-formaldehyde porous polymer sample with a high specific surface area. The prepared melamine-formaldehyde porous polymer is shown below. Figure 3 As shown.

[0065] Experiment 1: Adsorption effect of the material on pesticides

[0066] Adsorption test method: Prepare a 100 mg / L pesticide solution using pure water as solvent. Take 20 mL of pesticide solution and add 7 mg of adsorbent material to each solution. Place the solution in a constant temperature shaker and shake for 480 min. Set the environmental conditions to 210 r / min and 298 K until the adsorption reaches equilibrium.

[0067] Evaluation criteria: pesticides with an adsorption capacity higher than 150 mg / g are considered highly adsorbent pesticides, those with an adsorption capacity of 50-150 mg / g are considered moderately adsorbent pesticides, and those with an adsorption capacity lower than 50 mg / g are considered poorly adsorbent pesticides. Adsorption performance is shown in Table 4.

[0068] Table 4. Pesticide Adsorption Validation

[0069]

[0070] As shown in Table 4, the melamine-formaldehyde porous polymer prepared in the embodiments of the present invention exhibits significantly higher adsorption capacity for chlorpyrifos, dimethomorph, tebuconazole, thiamethoxam, paclobutrazol, and thiamethoxam than activated carbon. Specifically, the adsorption of chlorpyrifos, dimethomorph, and tebuconazole meets the standards for highly adsorbent pesticides, while the adsorption of thiamethoxam, paclobutrazol, and thiamethoxam meets the standards for moderately adsorbent pesticides. Therefore, it can be used for the adsorption and treatment of pesticide pollution.

[0071] Experiment 2: Study on pesticide adsorption loading

[0072] A 100 mg / L pesticide solution was prepared using purified water as the solvent. 20 mL of the pesticide solution was then added to 7 mg of mPMF, and the solution was placed in a constant-temperature shaker and shaken for 480 min. The environmental conditions were set at 210 r / min and 298 K until adsorption equilibrium was reached. The adsorption results are shown in Table 5.

[0073] Table 5. Detection of pesticide adsorption loading

[0074] type Loading capacity (or adsorption capacity, mg / g) chlorpyrifos 231.4 Dimethomorph 193.0 Tebuconazole 207.0 Thiamethoxam 71.6 Paclobutrazol 120.7 Thiamethoxam 110.4

[0075] Experiment 3: Study on pesticide adsorption loading in natural water environments

[0076] 10L of lake water was taken from Xiangsi Lake in Xixiangtang District, Nanning City, and pesticide was added to it to prepare a 100mg / L pesticide aqueous solution for adsorption study. The study method is as above (pesticide adsorption loading study), and the results are shown in Table 6.

[0077] Table 6 Adsorption Tests under Natural Water Body Conditions

[0078]

[0079]

[0080] As shown in Table 6, this adsorbent can eliminate interference in natural water bodies and effectively adsorb and remove pesticides from natural water bodies.

[0081] In summary, the melamine-formaldehyde porous polymer of the present invention exhibits excellent adsorption and removal performance for pesticides such as chlorpyrifos, dimethomorph, tebuconazole, thiamethoxam, paclobutrazol, and thiamethoxam, and can be applied to the adsorption and removal of pesticides in environmental water bodies.

[0082] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. The application of a melamine-formaldehyde porous polymer in the adsorption and treatment of pesticide pollution, characterized in that, The melamine-formaldehyde porous polymer is prepared by a pressure reaction of melamine and paraformaldehyde; the pressure of the pressure reaction is 1.5-3.0 MPa, the temperature is 130-180℃, and the time is 8-48 h. The pesticide is selected from chlorpyrifos, dimethomorph, tebuconazole, thiamethoxam, paclobutrazol and / or thiamethoxam.

2. The application according to claim 1, characterized in that: The preparation method of the melamine-formaldehyde porous polymer includes the following steps: dissolving melamine and paraformaldehyde in a solvent, reacting under certain pressure, temperature and time to prepare crude melamine-formaldehyde porous polymer, and washing and drying to obtain melamine-formaldehyde porous polymer.

3. The application according to claim 2, characterized in that, The pressure is 1.5 MPa.

4. The application according to claim 2, characterized in that, The temperature is 130°C.

5. The application according to claim 2, characterized in that, The time period is 24 hours.

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