Preparation method of gamma-cyclodextrin modified composite photocatalyst
阅读说明：本技术 一种γ-环糊精修饰的复合光催化剂的制备方法 (Preparation method of gamma-cyclodextrin modified composite photocatalyst ) 是由 武占省 何秀方 薛永涛 田飞 李云锋 张洛红 李庆 于 2020-07-24 设计创作，主要内容包括：本发明公开了一种γ-环糊精修饰的复合光催化剂的制备方法,具体按照以下步骤实施：步骤1、碱基化g-C<Sub>3</Sub>N<Sub>4</Sub>的制备：MoS<Sub>2</Sub>纳米花的制备：γ-环糊精(γ-CD)的预处理：使用硅烷偶联剂交联剂KH560对γ-CD进；行预处理修饰；步骤2、将步骤1得到的γ-CD、g-C<Sub>3</Sub>N<Sub>4</Sub>、MoS<Sub>2</Sub>进行复合,得用于降解草甘膦的复合光催化剂。通过具有空腔结构及众多的羟基官能团的γ-CD进行修饰,增加了MoS<Sub>2</Sub>与g-C<Sub>3</Sub>N<Sub>4</Sub>紧密接触,能够提高电子空穴分离能力,同时促进光催化剂在水中的亲水性,增加光催化剂的活性位点,有利于对草甘膦快速捕获,具有对草甘膦降解效率高、速率快的特点。(The invention discloses a preparation method of a gamma-cyclodextrin modified composite photocatalyst, which is implemented according to the following steps: step 1, basification of g-C 3 N 4 The preparation of (1): MoS 2 Preparing the nanoflower: pretreatment of gamma-cyclodextrin (gamma-CD): crosslinking agent KH560 with silane coupling agent to gamma-CD; performing pretreatment modification; step 2, the gamma-CD and the g-C obtained in the step 1 3 N 4 、MoS 2 And compounding to obtain the composite photocatalyst for degrading glyphosate. Through the modification of gamma-CD with a cavity structure and a plurality of hydroxyl functional groups, MoS is increased 2 And g-C 3 N 4 The close contact can improve the electron hole separation capability, simultaneously promote the hydrophilicity of the photocatalyst in water, increase the active sites of the photocatalyst, facilitate the rapid capture of glyphosate, and have the characteristics of high glyphosate degradation efficiency and high rate.)
1. A preparation method of a gamma-cyclodextrin modified composite photocatalyst is characterized by comprising the following steps:
step 1, basification of g-C3N4The preparation of (1):
mixing melamine, KCl and NH4Cl is mixed and ground thoroughly, Al is added2O3Placing the crucible into a box furnace, keeping the temperature at 550 ℃ for 4h at the heating rate of 2.5 ℃/min, cooling to room temperature, taking out the crucible to obtain yellow solid, grinding the yellow solid, placing the obtained solid powder into 100mL of deionized water, continuously magnetically stirring the mixture for 6h, performing suction filtration through a 0.22 mu m filter membrane, repeatedly washing the mixture by using distilled water, and performing drying treatment to obtain basic group-modified g-C3N4；
MoS2Preparing the nanoflower:
adding thiourea and sodium molybdate into 60ml of ultrapure water, magnetically stirring at room temperature, transferring the obtained solution into a 100ml of polytetrafluoroethylene hydrothermal reaction kettle, maintaining at the temperature of 180 ℃ and 210 ℃ for 20-24h, cooling to room temperature, repeatedly washing the obtained black mixture by using distilled water and absolute ethyl alcohol for three times through centrifugation, drying the obtained black solid at the temperature of 80 ℃ for 12h for later use, namely MoS2A nanoflower;
pretreatment of gamma-cyclodextrin (gamma-CD): crosslinking agent KH560 with silane coupling agent to gamma-CD; performing pretreatment modification;
step 2, obtaining the product in step 1gamma-CD, g-C of3N4、MoS2And compounding to obtain the composite photocatalyst for degrading glyphosate.
2. The method for preparing a composite photocatalyst modified by gamma-cyclodextrin according to claim 1, wherein the composite photocatalyst obtained in step 2 is MoS2/γ-CD/g-C3N4Said MoS2/γ-CD/g-C3N4The preparation method comprises the following steps: dispersing KH560 modified gamma-CD in deionized water, adjusting pH to 4-6 with glacial acetic acid, stirring for complete hydrolysis, adding basic g-C3N4Then ultrasonic treatment is carried out for 30-40min, and then the suspension is refluxed for 8-10h at the temperature of 80-90 ℃ to obtain the gamma-CD/g-C3N4Then MoS2Nanometer flower and gamma-CD/g-C3N4And compounding to prepare the composite photocatalyst.
3. The method for preparing a composite photocatalyst modified by gamma-cyclodextrin according to claim 1, wherein the composite photocatalyst obtained in step 2 is g-C3N4/γ-CD/MoS2Said g-C3N4/γ-CD/MoS2The preparation method comprises the following steps: dispersing KH560 modified gamma-CD in deionized water, adjusting pH to 4-6 with glacial acetic acid, stirring for complete hydrolysis, and adding MoS2Performing ultrasonic treatment on the nanoflower for 30-40min, and refluxing the suspension at 80-90 ℃ for 8-10h to obtain gamma-CD/MoS2Then the obtained gamma-CD/MoS2And basic g-C3N4And compounding to obtain the composite photocatalyst.
4. The method for preparing the composite photocatalyst modified by gamma-cyclodextrin according to claim 1, wherein the composite photocatalyst obtained in the step 2 is gamma-CD/MoS2/g-C3N4The gamma-CD/MoS2/g-C3N4The preparation method comprises the following steps: basic group-forming g-C3N4And MoS2Preparing MoS compositely2/g-C3N4Dispersing KH560 modified gamma-CD in deionized water, adjusting pH to 4-6 with glacial acetic acid, stirring for complete hydrolysis, and adding MoS2/g-C3N4Then carrying out ultrasonic treatment for 30-40min, and then refluxing the suspension at 80-90 ℃ for 8-10h to obtain the composite photocatalyst.
5. The method for preparing the gamma-cyclodextrin modified composite photocatalyst as claimed in claim 1, wherein in the step 1, the ratio of melamine: KCl: NH (NH)4The ratio of Cl is 15-10:15-10: 1.
6. The method for preparing the gamma-cyclodextrin modified composite photocatalyst as claimed in claim 1, wherein in the step 1, the ratio of thiourea to sodium molybdate is 2:1-4: 1.
7. The method for preparing the gamma-cyclodextrin modified composite photocatalyst as claimed in claim 1, wherein in the step 1, KH560 is used in an amount of 1-10 mL.
8. The method for preparing the gamma-cyclodextrin modified composite photocatalyst as claimed in claim 1, wherein in the step 2, the mass of gamma-CD is 3-6g, g-C3N4Has a mass of 1-2g, MoS2The mass of (B) is 0.1-0.2 g.
9. The method for preparing a gamma-cyclodextrin modified composite photocatalyst as claimed in claim 1, wherein the basic g-C in step 1 is3N4The drying treatment of (1) is drying at 80 ℃ for 12 hours.
10. The method for preparing a gamma-cyclodextrin modified composite photocatalyst as claimed in claim 1, wherein the MoS in the step 1 is2In the preparation of the nanoflower, the magnetic stirring time is 1h at room temperature.
Technical Field
The invention belongs to the technical field of novel materials, and relates to a preparation method of a gamma-cyclodextrin modified composite photocatalyst.
Background
Glyphosate (i.e., N- (phosphonomethyl) glycine) is a broad spectrum post-emergence herbicide widely used in agriculture, parks, gardens, and the like. Glyphosate is a competitive congener of phosphoenolpyruvate, is an active substrate of 5-enolpyruvate 3-enzyme phosphate synthase, and is necessary for synthesizing aromatic amino acids tryptophan, tyrosine and phenylalanine, so that the aim of weeding is fulfilled by blocking the synthesis of enzymes in plants. However, the repeated use of glyphosate without diverse weed management increases the selection of resistance and tolerance of the weeds to chemicals, resulting in increasing rates of glyphosate application. Because glyphosate has strong resistance to chemical degradation and sunlight and has moderate persistence in soil (average half-life of 47 days), it can directly pass through surface water and ground water or runoff, leach into water, and accumulate to cause pollution.
The removal of glyphosate attracts the research of numerous scholars, and the treatment method of glyphosate mainly comprises a physical method, a biochemical method and a chemical oxidation method. The photocatalysis method has wide natural light source, simple operation and low cost, can mineralize organic pollutants, does not generate secondary pollution and is widely concerned. With conventional semiconductors (e.g. TiO)2g-C compared with ZnO)3N4The material has a two-dimensional (2D) layered structure, has a pi conjugated system and a proper band gap width (2.7 eV), has unique photoelectric properties, high chemical stability and good visible light absorption (about 450-460 nm), is rich in raw materials, is non-toxic and harmless, and is widely used in photocatalytic degradation research.
However, g-C3N4There are also some problems that result in poor photocatalytic degradation ability: (1) the specific surface area is low; (2) the visible light response capability is poor; (3) the electron hole is easy to recombine, so that the g-C prepared by the method has the advantages of higher specific surface area, wider spectral absorption range and higher electron hole separation efficiency3N4The base photocatalyst becomes an important means for improving the photocatalytic degradation activity. To increase g-C3N4The utilization efficiency of the compound can be improved by prolonging the electron life and further improving the g-C by compounding with other semiconductors3N4Efficiency of use of, among numerous semiconductors, MoS2Because of its narrow band gap width and wide spectral range, it is of great interest to provide a composite photocatalyst with the possibility of infrared absorption. Shi et al [ Rationally designed MoS2/protonated g-C3N4nanosheet composites as photocatalysts with an excellentsynergistic effect toward photocatalytic degradation of organic pollutants]Design MoS2Protonated g-C3N4The degradation of the methylene orange under the optimal proportion of the nano sheets is pure g-C3N48 times of the total weight of the product. But in the present studyg-C prepared3N4/MoS2The composite photocatalyst still has the phenomenon of less active sites and low degradation efficiency, so that g-C can be modified by a series of methods3N4/MoS2The composite photocatalyst further improves the degradation efficiency.
Since Cyclodextrins (CD) are non-toxic, biodegradable, can be produced on an industrial scale, and can be used in their dissolved or solid, natural or modified forms. And CDs also have a characteristic macrocyclic structure and very specific properties due to the hydrophobic cavity, which enables them to encapsulate other substances, and the hydrophilic outer cavity, which forms complexes that exhibit a host-guest relationship. The physical, chemical and/or biological properties of the target molecule (guest) can thus be modified and/or improved depending on the target. Furthermore, due to their excellent chemical reactivity, they can also be relatively easily synthesized into innovative materials for use in the field of decontamination from various parts of the environment (e.g. water, air, soils and sediments). Saha et al [ beta-Cyclodextrin modified hydroxide ion: Synthesis, chromatography and adsorption efficiency from aqueous solution]By modifying zirconium dioxide with beta-CD, the adsorbent (CY-HZO) prepared has a surface site concentration of 26nm of original zirconium dioxide (HZO)-1Increased to 6300nm-1Primarily because β -CD can provide more hydroxyl functionality, which is critical to enhance fluoride removal.
Disclosure of Invention
The invention aims to provide a preparation method of a gamma-cyclodextrin modified composite photocatalyst, which has the characteristics of high glyphosate degradation efficiency and high rate.
The technical scheme adopted by the invention is that the preparation method of the gamma-cyclodextrin modified composite photocatalyst is implemented according to the following steps:
step 1, basification of g-C3N4The preparation of (1):
mixing melamine, KCl and NH4Cl is mixed and ground thoroughly, Al is added2O3Placing the crucible into a box furnace, and maintaining at 550 deg.CHeating for 4h at a heating rate of 2.5 ℃/min, cooling to room temperature, taking out to obtain a yellow solid, grinding, placing the obtained solid powder in 100mL deionized water, continuously magnetically stirring for 6h, performing suction filtration through a 0.22 mu m filter membrane, repeatedly washing with distilled water, and drying to obtain basic group-modified g-C3N4；
MoS2Preparing the nanoflower:
adding thiourea and sodium molybdate into 60ml of ultrapure water, magnetically stirring at room temperature, transferring the obtained solution into a 100ml of polytetrafluoroethylene hydrothermal reaction kettle, maintaining at the temperature of 180 ℃ and 210 ℃ for 20-24h, cooling to room temperature, repeatedly washing the obtained black mixture by using distilled water and absolute ethyl alcohol for three times through centrifugation, drying the obtained black solid at the temperature of 80 ℃ for 12h for later use, namely MoS2A nanoflower;
pretreatment of gamma-cyclodextrin (gamma-CD): crosslinking agent KH560 with silane coupling agent to gamma-CD; performing pretreatment modification;
step 2, the gamma-CD and the g-C obtained in the step 13N4、MoS2And compounding to obtain the composite photocatalyst for degrading glyphosate.
The invention is also characterized in that:
the composite photocatalyst obtained in the step 2 is MoS2/γ-CD/g-C3N4Said MoS2/γ-CD/g-C3N4The preparation method comprises the following steps: dispersing KH560 modified gamma-CD in deionized water, adjusting pH to 4-6 with glacial acetic acid, stirring for complete hydrolysis, adding basic g-C3N4Then ultrasonic treatment is carried out for 30-40min, and then the suspension is refluxed for 8-10h at the temperature of 80-90 ℃ to obtain the gamma-CD/g-C3N4Then MoS2Nanometer flower and gamma-CD/g-C3N4And compounding to prepare the composite photocatalyst.
The composite photocatalyst obtained in the step 2 is g-C3N4/γ-CD/MoS2Said g-C3N4/γ-CD/MoS2The preparation method comprises the following steps: dispersing KH560 modified gamma-CD into deionized water, and usingAdjusting pH to 4-6 with glacial acetic acid, stirring for complete hydrolysis, adding MoS2Performing ultrasonic treatment on the nanoflower for 30-40min, and refluxing the suspension at 80-90 ℃ for 8-10h to obtain gamma-CD/MoS2Then the obtained gamma-CD/MoS2And basic g-C3N4And compounding to obtain the composite photocatalyst.
The composite photocatalyst gamma-CD/MoS obtained in the step 22/g-C3N4The gamma-CD/MoS2/g-C3N4The preparation method comprises the following steps: basic group-forming g-C3N4And MoS2Preparing MoS compositely2/g-C3N4Dispersing KH560 modified gamma-CD in deionized water, adjusting pH to 4-6 with glacial acetic acid, stirring for complete hydrolysis, and adding MoS2/g-C3N4Then carrying out ultrasonic treatment for 30-40min, and then refluxing the suspension at 80-90 ℃ for 8-10h to obtain the composite photocatalyst.
In step 1, melamine: KCl: NH (NH)4The ratio of Cl is 15-10:15-10: 1.
In the step 1, the ratio of thiourea to sodium molybdate is 2:1-4: 1.
In the step 1, the dosage of KH560 is 1-10 mL.
In step 2, the mass of the gamma-CD is 3-6g, g-C3N4Has a mass of 1-2g, MoS2The mass of (B) is 0.1-0.2 g.
Basification of step 1 g-C3N4The drying treatment of (1) is drying at 80 ℃ for 12 hours.
MoS of step 12In the preparation of the nanoflower, the magnetic stirring time is 1h at room temperature.
The invention has the beneficial effects that: the preparation method of the gamma-cyclodextrin modified composite photocatalyst has the characteristics of high glyphosate degradation efficiency and high speed, and MoS is carried out2And g-C3N4Compounding, grafting by using gamma-CD, and increasing MoS2And g-C3N4In close contact, electron holes generated by light irradiation can shorten electron transfer pathThe service life of electrons is prolonged, the electron hole separation capability is improved, and the glyphosate removal efficiency is higher. The adopted gamma-CD has a cavity structure, and the gamma-CD has a plurality of hydroxyl functional groups, so that the hydrophilicity of the photocatalyst in water can be promoted, the active sites of the photocatalyst are increased, the rapid capture of glyphosate is facilitated, and the removal efficiency of the glyphosate is effectively improved.
Drawings
FIG. 1 is a scanning electron microscope image of a composite photocatalyst prepared in the preparation method of a gamma-cyclodextrin modified composite photocatalyst according to the present invention;
FIG. 2 is a graph showing the degradation rate of different photocatalysts on glyphosate in the preparation method of the gamma-cyclodextrin modified composite photocatalyst of the present invention.
Detailed Description
The present invention will be described in detail with reference to the following embodiments.
The invention relates to a preparation method of a gamma-cyclodextrin modified composite photocatalyst, which is implemented according to the following steps:
step 1, basification of g-C3N4The preparation of (1):
mixing melamine, KCl and NH4Cl is mixed and ground thoroughly, Al is added2O3Placing the crucible into a box furnace, keeping the temperature at 550 ℃ for 4h at the heating rate of 2.5 ℃/min, cooling to room temperature, taking out the crucible to obtain yellow solid, grinding the yellow solid, placing the obtained solid powder into 100mL of deionized water, continuously magnetically stirring the mixture for 6h, performing suction filtration through a 0.22 mu m filter membrane, repeatedly washing the mixture by using distilled water, and performing drying treatment to obtain basic group-modified g-C3N4；
Basification of step 1 g-C3N4The drying treatment of (1) is drying at 80 ℃ for 12 hours.
In step 1, melamine: KCl: NH (NH)4The ratio of Cl is 15-10:15-10: 1.
MoS2Preparing the nanoflower:
adding thiourea and sodium molybdate to 60ml of ultrapure water, magnetically stirring at room temperature, and obtaining a solutionTransferring the mixture to a 100ml polytetrafluoroethylene hydrothermal reaction kettle, maintaining the temperature at 180-210 ℃ for 20-24h, cooling the mixture to room temperature, repeatedly washing the obtained black mixture by centrifugation for three times by using distilled water and absolute ethyl alcohol, and drying the obtained black solid at 80 ℃ for 12h for later use, namely MoS2A nanoflower;
in the step 1, the ratio of thiourea to sodium molybdate is 2:1-4: 1.
MoS of step 12In the preparation of the nanoflower, the magnetic stirring time is 1h at room temperature.
Pretreatment of gamma-cyclodextrin (gamma-CD): crosslinking agent KH560 with silane coupling agent to gamma-CD; performing pretreatment modification;
in the step 1, the dosage of KH560 is 1-10 mL.
Step 2, the gamma-CD and the g-C obtained in the step 13N4、MoS2And compounding to obtain the composite photocatalyst for degrading glyphosate.
In step 2, the mass of the gamma-CD is 3-6g, g-C3N4Has a mass of 1-2g, MoS2The mass of the photocatalyst is 0.1-0.2g, and the prepared composite photocatalyst is gamma-CD/MoS2/g-C3N4、MoS2/γ-CD/g-C3N4、g-C3N4/γ-CD/MoS2Any one of (1).
The composite photocatalyst obtained in the step 2 is MoS2/γ-CD/g-C3N4Said MoS2/γ-CD/g-C3N4The preparation method comprises the following steps: dispersing KH560 modified gamma-CD in deionized water, adjusting pH to 4-6 with glacial acetic acid, stirring for complete hydrolysis, adding basic g-C3N4Then ultrasonic treatment is carried out for 30-40min, and then the suspension is refluxed for 8-10h at the temperature of 80-90 ℃ to obtain the gamma-CD/g-C3N4Then MoS2Nanometer flower and gamma-CD/g-C3N4And compounding to prepare the composite photocatalyst.
Mixing 5% of MoS2First dispersed in 50mL DMF, sonicated for 2h, then 1-2g of gamma-CD/g-C3N4Adding into the above mixed solutionSub-ultrasonic for 1h, magnetically stirring for 12h at room temperature to ensure MoS2And gamma-CD/g-C3N4And (4) successfully compounding. Then DMF is removed by a reduced pressure distillation method to obtain the composite photocatalyst MoS2/γ-CD/g-C3N4。
The composite photocatalyst obtained in the step 2 is g-C3N4/γ-CD/MoS2Said g-C3N4/γ-CD/MoS2The preparation method comprises the following steps: dispersing KH560 modified gamma-CD in deionized water, adjusting pH to 4-6 with glacial acetic acid, stirring for complete hydrolysis, and adding MoS2Performing ultrasonic treatment on the nanoflower for 30-40min, and refluxing the suspension at 80-90 ℃ for 8-10h to obtain gamma-CD/MoS2Then the obtained gamma-CD/MoS2And basic g-C3N4And compounding to obtain the composite photocatalyst.
Basic g-C of 5% mass fraction3N4First dispersed in 50mL DMF, sonicated for 2h, then 1-2g of gamma-CD/MoS2Adding into the above mixture, performing ultrasonic treatment for 1 hr again, magnetically stirring at room temperature for 12 hr to ensure g-C3N4And gamma-CD/MoS2And (4) successfully compounding. Then DMF is removed by a reduced pressure distillation method to obtain the composite photocatalyst g-C3N4/γ-CD/MoS2。
The composite photocatalyst gamma-CD/MoS obtained in the step 22/g-C3N4The gamma-CD/MoS2/g-C3N4The preparation method comprises the following steps: basic group-forming g-C3N4And MoS2Preparing MoS compositely2/g-C3N4Dispersing KH560 modified gamma-CD in deionized water, adjusting pH to 4-6 with glacial acetic acid, stirring for complete hydrolysis, and adding MoS2/g-C3N4Then carrying out ultrasonic treatment for 30-40min, and then refluxing the suspension at 80-90 ℃ for 8-10h to obtain the composite photocatalyst.
Basic g-C of 5% mass fraction3N4First dispersed in 50mL DMF, sonicated for 2h, then 1-2g of MoS2Adding into the above mixed solutionPerforming ultrasonic treatment again for 1h at room temperature, and magnetically stirring for 12h at room temperature to ensure g-C3N4And MoS2And (4) successfully compounding. Then DMF is removed by a reduced pressure distillation method to obtain the composite photocatalyst gamma-CD/MoS2/g-C3N4。
The gamma-cyclodextrin modified MoS prepared by the preparation method of the gamma-cyclodextrin modified composite photocatalyst2/g-C3N4The composite photocatalyst is used for degrading glyphosate, and specifically, the composite photocatalyst prepared by the preparation method of the composite photocatalyst modified by gamma-cyclodextrin is weighed, and the glyphosate is degraded under the illumination of different light sources. The mass of the photocatalyst is 20mg, the concentration of the glyphosate is 9g/L, and the volume of the photocatalyst is 50mL, the spectrum absorption range of the composite photocatalyst prepared by the preparation method of the gamma-cyclodextrin modified composite photocatalyst reaches 500nm, and the degradation of the glyphosate within 170min under the irradiation of simulated sunlight reaches more than 60%.
Grafting of gamma-cyclodextrin to MoS by using silane crosslinker KH5602、g-C3N4The photocatalysts with different compounding sequences are prepared on the surface of the composite photocatalyst, and the prepared composite photocatalyst has rich active sites, a high spectrum absorption range and good electron hole separation capability, so that the efficient degradation of the glyphosate is realized.