阅读说明：本技术 一种二维铁氧化物纳米片催化剂的制备方法和应用 (Preparation method and application of two-dimensional iron oxide nanosheet catalyst ) 是由 王维雪 岳仪凡 王慧慧 陈奕倩 陈哲 王祥科 于 2019-08-30 设计创作，主要内容包括：本发明公开了属于类芬顿催化剂制备技术领域的一种二维铁氧化物纳米片催化剂的制备方法和应用。包括步骤：(1)硅酸四乙酯与四甲基氢氧化铵混合后,经水热反应得到模板RUB-15；(2)混合铁源FeCl<Sub>3</Sub>·6H<Sub>2</Sub>O与步骤(1)所述模板RUB-15后,研磨均匀得到前体混合物,所述前体混合物经煅烧得到混合物；(3)刻蚀步骤(2)所述混合物中模板RUB-15,得到所述二维铁氧化物纳米片催化剂。所得催化剂用于活化过一硫酸盐产生自由基,以降解有机污染物。相比于传统技术,本发明制备的铁基催化剂无需与其他材料结合,性能优异、方法简单、成本低廉；本发明提供的层间限域生长策略为二维结构纳米材料的合成开辟了新的视野。(The invention discloses a preparation method and application of a two-dimensional iron oxide nanosheet catalyst, and belongs to the technical field of Fenton-like catalyst preparation. The method comprises the following steps: (1) tetraethyl silicate and tetramethylammonium hydroxide are mixed and then subjected to hydrothermal reaction to obtain a template RUB-15; (2) mixed iron source FeCl 3 ·6H 2 Grinding the template RUB-15 obtained in the step (1) with O uniformly to obtain a precursor mixture, and calcining the precursor mixture to obtain a mixture; (3) and (3) etching the template RUB-15 in the mixture obtained in the step (2) to obtain the two-dimensional iron oxide nanosheet catalyst. The obtained catalyst is used forThe peroxymonosulfate is activated to generate free radicals to degrade organic contaminants. Compared with the traditional technology, the iron-based catalyst prepared by the invention does not need to be combined with other materials, and has the advantages of excellent performance, simple method and low cost; the interlayer confinement growth strategy provided by the invention opens up a new field of view for the synthesis of the two-dimensional structure nano material.)

1. A preparation method of a two-dimensional iron oxide nanosheet catalyst is characterized by comprising the following steps:

(1) Tetraethyl silicate and tetramethylammonium hydroxide are mixed and then subjected to hydrothermal reaction to obtain a template RUB-15;

(2) Mixed iron source FeCl₃·6H₂Grinding the template RUB-15 obtained in the step (1) with O uniformly to obtain a precursor mixture, and calcining the precursor mixture to obtain a mixture;

(3) And (3) etching the template RUB-15 in the mixture obtained in the step (2) to obtain the two-dimensional iron oxide nanosheet catalyst.

2. The method according to claim 1, wherein the molar ratio of tetraethyl silicate to tetramethylammonium hydroxide in step (1) is 1:1, the hydrothermal reaction temperature is 140 ℃, and the reaction time is 14 days.

3. The method according to claim 1, wherein the template RUB-15 obtained in step (1) has a fixed interlayer spacing of 1.4 nm.

4. The method according to claim 1, wherein the iron source FeCl in the step (2)₃·6H₂The mass ratio of O to the template RUB-15 is 0.1: 1-10: 1.

5. The preparation method according to claim 1, wherein the calcination in the step (2) is performed in an atmosphere of air, oxygen, argon, nitrogen or helium, the calcination temperature is 350 ℃ to 650 ℃, the temperature rise rate is 1 ℃/min to 10 ℃/min, and the heat preservation time is 1h to 3 h.

6. The preparation method according to claim 1, wherein in the step (3), the template RUB-15 in the mixture in the step (2) is etched by using a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 1mol/L to 5 mol/L.

7. Use of a two-dimensional iron oxide nanosheet catalyst as defined in claim 1, wherein the two-dimensional iron oxide nanosheet catalyst is used to activate peroxymonosulfate to degrade organic contaminants in a body of water.

8. The application of claim 7, wherein the two-dimensional iron oxide nanosheet catalyst is uniformly mixed with an aqueous solution of an organic pollutant, and after equilibrium of adsorption, degradation is initiated by the addition of peroxymonosulfate.

9. The use of claim 7, wherein the organic contaminants comprise one or more of bisphenol A, 2-chlorophenol, 4-chlorophenol, 2, 4-dichlorophenol, 2,4, 6-trichlorophenol, phenol, tetracycline.

10. The use of claim 7, wherein the two-dimensional iron oxide nanoplates can be recycled more than 5 times; the cyclic regeneration mode is washing and drying, and calcining after washing and drying.

Technical Field

the invention belongs to the technical field of Fenton-like catalyst preparation, and particularly relates to a preparation method and application of a two-dimensional iron oxide nanosheet catalyst.

Background

Using peroxymonosulfate (PMS, HSO)₅ ^-) Activated fenton-like advanced oxidation technologies (AOPs) have significant reactivity to a number of refractory organic pollutants and are considered as a promising strategy for remediation of organic pollution systems. However, due to the low reactivity of PMS itself, an efficient activation procedure must be performed to release the oxidative radicals. The reaction free radicals generated by the carbonaceous catalyst under the high oxidation environment may partially oxidize and damage the surface defect sites of the catalyst, resulting in poor stability. The change in the chemical state and unoccupied orbitals of the metal in the metal-based catalyst is thought to enable sufficient electron transfer in the redox cycle to effectively activate the PMS molecules to generate radicals, but is limited by cost and elution problems. For many years, people have been dedicated to the development of heterogeneous iron catalysts, iron is the fourth most abundant element in the earth crust, is nontoxic and harmless, has wide raw materials and low cost, and is considered as the most promising transition metal catalyst. However, unlike the highly activated PMS performance of cobalt-based catalysts, heterogeneous iron-based catalysts have been poor in activity and need to be combined with other materials to improve performance, which severely limits their further development.

For example, Bao and the like adopt a one-step dissolution combustion method to prepare nano bimetal Co/Fe oxide, PMS is activated to mineralize and degrade sulfamethoxazole, and the conversion mechanism of the oxide is except for free radical SO₄ ^·-OH and OOH, but also non-radical oxidation combined electron transfer processes. Ren et al spinel magnet MFe₂O₄(MCo, Cu, Mn, Zn) for the degradation of dibutyl phthalate, several catalysts in the order of CoFe activity₂O₄>CuFe₂O₄>MnFe₂O₄>ZnFe₂O₄，PMS/MFe₂O₄The active species of the system were identified as sulfate radicals and hydroxyl radicals.

Disclosure of Invention

The invention aims to provide a preparation method and application of a two-dimensional iron oxide nanosheet catalyst, and the specific technical scheme is as follows:

The preparation method of the two-dimensional iron oxide nanosheet catalyst comprises the following steps:

(1) Tetraethyl silicate and tetramethylammonium hydroxide are mixed and then subjected to hydrothermal reaction to obtain a template RUB-15;

(2) Mixed iron source FeCl₃·6H₂Grinding the template RUB-15 obtained in the step (1) with O uniformly to obtain a precursor mixture, and calcining the precursor mixture to obtain a mixture;

(3) And (3) etching the template RUB-15 in the mixture obtained in the step (2) to obtain the two-dimensional iron oxide nanosheet catalyst.

The molar ratio of tetraethyl silicate to tetramethylammonium hydroxide in the step (1) is 1:1, the hydrothermal reaction temperature is 140 ℃, and the reaction time is 14 days.

The specific operation is as follows: and magnetically stirring the tetramethylammonium hydroxide and tetraethyl silicate solution for 24 hours at room temperature according to the molar ratio of 1:1 to obtain a milky white suspension, and then transferring the milky white suspension into a hydrothermal reaction kettle to react for 14 days at 140 ℃ to obtain the template RUB-15.

The template RUB-15 obtained in the step (1) is a two-dimensional layered silicate, a zeolite precursor and a rectangular nanosheet with a regular morphology and a fixed interlayer spacing.

In the step (2), iron source FeCl is adopted₃·6H₂The mass ratio of the O to the template RUB-15 is 0.1: 1-10: 1.

And (3) the precursor mixture obtained after the step (2) is uniformly ground is fluffy.

The calcination in the step (2) is carried out in the atmosphere of air, oxygen, argon, nitrogen or helium, the calcination temperature is 350-650 ℃, the heating rate is 1-10 ℃/min, and the heat preservation time is 1-3 h.

The precursor mixture in the step (2) is calcined and stabilized at high temperature; the method specifically comprises the following steps: in the high-temperature calcination process of the precursor mixture, an iron source is gradually melted and enters the layers of the templates RUB-15 for limited-area growth, and the formed two-dimensional iron oxide and the templates RUB-15 are alternately mixed and grow.

in the step (3), the template RUB-15 in the mixture in the step (2) is etched by using a sodium hydroxide solution, wherein the concentration of the sodium hydroxide solution is 1-5 mol/L.

And the etching is specifically to soak the mixture in a sodium hydroxide solution, wash the template RUB-15 with a large amount of water after the template RUB-15 is corroded, and dry to obtain a target product.

The two-dimensional iron oxide nanosheet catalyst obtained in the step (3) has a fixed layer thickness.

The application of the two-dimensional iron oxide nanosheet catalyst is characterized in that the two-dimensional iron oxide nanosheet catalyst is used for activating peroxymonosulfate so as to degrade organic pollutants in a water body.

Specifically, the two-dimensional iron oxide nanosheet catalyst is used in a fenton-like reaction for activating peroxymonosulfate to degrade organic pollutants in a water body.

The specific operation of catalytic degradation is as follows: the two-dimensional iron oxide nanosheet catalyst and the organic pollutant aqueous solution are uniformly mixed, and degradation is started by adding peroxymonosulfate after adsorption balance.

Further, the catalytic degradation was carried out according to the following method: at room temperature of 25 ℃, adding 10mg of two-dimensional iron oxide nanosheet catalyst into 50mL of organic pollutant aqueous solution, and mechanically stirring, wherein the concentration of the organic pollutant solution is 20 mg/L. The reaction solution was adjusted to pH 6.0 with 0.1mol/L NaOH solution and 0.1mol/L HCl solution, and the timer was started. After 30min, the adsorption equilibrium is reached and sampling is carried out. 25mg of peroxymonosulfate was then added, the reaction timing was started and samples were taken at regular intervals. The sample liquid is filtered by a 0.45 mu m aqueous polyether sulfone disposable filter head, and the concentration of the organic pollutants is measured by a high performance liquid chromatograph.

the organic pollutants comprise one or more of bisphenol A, 2-chlorophenol, 4-chlorophenol, 2, 4-dichlorophenol, 2,4, 6-trichlorophenol, phenol and tetracycline.

The two-dimensional iron oxide nanosheets can be recycled for more than 5 times; the cyclic regeneration mode is washing drying and calcining after washing drying, and the cyclic regeneration mode is further preferably calcining after washing drying.

The cyclic regeneration mode is calcination after washing and drying, wherein the calcination condition is the same as the calcination condition in the step (2) of the preparation method.

The invention has the beneficial effects that:

(1) The invention combines an interlayer confinement growth strategy and a melt infiltration method, takes RUB-15 with regular appearance and fixed interlayer distance of 1.4nm as a template, and FeCl with low melting point₃·6H₂And O forms a molten state at high temperature and enters the RUB-15 layer to grow, and then forms a trans-structure by etching the template, so that the iron oxide nanosheet with the regular two-dimensional structure is synthesized for the first time and is used as the Fenton-like reaction catalyst.

(2) The two-dimensional thin-layer iron oxide obtained by the invention has stronger in-plane chemical bonds and relatively weaker out-of-plane van der waals bonds, compared with a bulk material, a large number of atoms exposed on the surface of the two-dimensional material can provide different chemical states, and a specific exposed surface can effectively regulate and control chemical activity.

(3) The Fenton-like reaction catalyst can effectively activate PMS (peroxymonosulfate) in a solution, decompose PMS to generate oxidizing free radicals, and further mineralize and degrade organic pollutants in an organic polluted water body. Compared with the heterogeneous iron-based Fenton catalyst prepared by the traditional method, the iron-based catalyst prepared by the method disclosed by the invention does not need to be combined with other materials, is excellent in performance, simple in method, low in cost and stable in performance, is a successful example for applying the iron oxide to remediation of the organic polluted water body, and is a successful model for widely developing the iron-based catalyst.

(4) The interlayer confinement growth strategy provided by the invention is suitable for synthesis of a plurality of two-dimensional materials, the template can be any layered material, and inserted atoms and molecules can also be freely selected.

Drawings

FIG. 1 is a FeCl iron source in example 1₃·6H₂And obtaining an XRD pattern of a sample obtained by mixing O and the template RUB-15 in different proportions.

FIG. 2 is a diagram showing FeCl as an iron source in example 1₃·6H₂And obtaining a Raman image of the sample obtained by mixing O with the template RUB-15 in different proportions.

FIG. 3 is a FeCl iron source in example 1₃·6H₂TEM images of samples obtained by different ratios of O and the template RUB-15.

FIG. 4 shows Fe in example 2_xO_y、Fe_xO_y-10:1、Fe_xO_y-1:1、Fe_xO_yComparison of BPA degrading performance of activated PMS at-0.1: 1.

FIG. 5 shows Fe regenerated in example 3 by two regeneration modes_xO_y-1:1 degradation efficiency of catalyst in activated PMS degradation bisphenol A cycle experiment.

Detailed Description

The invention provides a preparation method and application of a two-dimensional iron oxide nanosheet catalyst, and the invention is further described with reference to the following embodiments and accompanying drawings.