阅读说明：本技术 一种金属离子共掺杂BiOBr微球、制备方法及其应用 (Metal ion co-doped BiOBr microsphere, preparation method and application thereof ) 是由 张富春 王魏 戴蓉 吴乔 张磊 门婧茹 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种金属离子共掺杂BiOBr微球、制备方法及其应用,所述微球具体为Bi<Sub>1-x-</Sub><Sub>y</Sub>Cd<Sub>x</Sub>Fe<Sub>y</Sub>OBr,其中x＝y＝0.02,或者Bi<Sub>1-x</Sub>Cd<Sub>x</Sub>OBr,其中x＝0.02,或者Bi<Sub>1-x</Sub>Fe<Sub>x</Sub>OBr,其中x＝0.02,所述制备方法包括将铋源和CTAB分别溶于有机溶剂中,超声处理,磁力搅拌；混合得混合溶液,加入金属离子,转移到高压釜中,加上爆破膜,进行微波水热反应；反应结束后,将产物冷却至室温,用去离子水清洗数次,用乙醇充分洗涤,干燥。本发明制备方法条件温和、工艺简单,在模拟太阳光照射下可高效的降解污水中的染料和抗生素等有机污染物。(The invention discloses a metal ion co-doped BiOBr microsphere, a preparation method and application thereof, wherein the microsphere is particularly Bi 1‑x‑ y Cd x Fe y OBr, where x ═ y ═ 0.02, or Bi 1‑x Cd x OBr, where x is 0.02, or Bi 1‑x Fe x OBr, wherein x is 0.02, the preparation method comprises the steps of respectively dissolving a bismuth source and CTAB in an organic solvent, carrying out ultrasonic treatment, and carrying out magnetic stirring; mixing to obtain a mixed solution, adding metal ions, transferring into a high-pressure kettle, adding a rupture membrane, and carrying out microwave hydrothermal reaction; after the reaction is finished, cooling the product to room temperature, washing the product for several times by using deionized water, fully washing the product by using ethanol, and drying the product. The preparation method has mild conditions and simple process, and can efficiently degrade organic pollutants such as dye, antibiotics and the like in the sewage under the irradiation of simulated sunlight.)

1. The metal ion co-doped BiOBr microsphere is characterized by specifically being Bi_1-x-yCd_xFe_yOBr, where x ═ y ═ 0.02, or Bi_1-xCd_xOBr, where x is 0.02, or Bi_1-xFe_xOBr, where x is 0.02.

2. The preparation method of the metal ion co-doped BiOBr microspheres according to claim 1, which comprises the following steps:

(1) respectively dissolving a bismuth source and CTAB in an organic solvent, carrying out ultrasonic treatment, and carrying out magnetic stirring;

(2) mixing the two solutions, stirring to obtain precursor solution, adding 2 wt% Cd (NO) into the precursor solution₃)₂·4H₂O, obtaining a mixed solution, transferring the mixed solution into a high-pressure autoclave with a polytetrafluoroethylene lining, adding a rupture membrane, and placing the high-pressure autoclave in a microwave hydrothermal reactor system for reaction;

(3) after the reaction is finished, cooling the product to room temperature, washing the product for a plurality of times by deionized water, fully washing the product by ethanol, and drying the product to obtain a product Bi_1-xCd_xOBr; 2 wt% Cd (NO) in step (2)₃)₂·4H₂O to 2 wt% Fe (NO)₃)₃·9H₂O, product Bi obtained_1-xFe_xOBr; 2 wt% Cd (NO) in step (2)₃)₂·4H₂Continuously adding 2 wt% Fe (NO) based on O₃)₃·9H₂O to obtain a product Bi_1-x-yCd_xFe_yOBr。

3. The preparation method of the metal ion co-doped BiOBr microsphere according to claim 2, wherein the bismuth source in the step (1) is soluble salt.

4. The preparation method of the metal ion co-doped BiOBr microsphere according to claim 2, wherein the molar ratio of the bismuth source to CTAB in the step (1) is (1-3): (1-3).

5. The method for preparing metal ion co-doped BiOBr microspheres according to claim 2, wherein the organic solvent is ethylene glycol.

6. The preparation method of the metal ion co-doped BiOBr microsphere according to claim 2, wherein the final temperature of the microwave reaction in the step (2) is 180 ℃, wherein the heating time of the heating stage at 0-60 ℃ is 3min, the heating time of the heating stage at 60-120 ℃ is 3min, the heating time of the heating stage at 120-180 ℃ is 3min, and the heating time of the holding stage at 180-180 ℃ is 15 min.

7. The preparation method of the metal ion co-doped BiOBr microsphere according to claim 2, wherein the drying condition in the step (3) is 60-80 ℃ for 10-15 h.

8. A composite photocatalyst, which is prepared from the metal ion co-doped BiOBr microsphere in claim 1.

9. Use of the composite photocatalyst of claim 8 in wastewater treatment.

10. The use of claim 9, wherein the composite photocatalyst is added in an amount of 50mg per 50ml of rhodamine B solution.

Technical Field

The invention relates to the technical field of water treatment, in particular to a metal ion co-doped BiOBr microsphere, a preparation method and application thereof.

Background

With the increase of the amount of polluted water for decades, the effective treatment of polluted water has become an urgent problem. Organic pollutants as one of the main pollutants, although many treatment methods can solve the problem at present, the method has certain limitations, which is a power source for developing a low-cost and high-efficiency water purification technology to solve serious environmental problems and meet the environmental requirements of governments, and titanium dioxide using a single crystal electrode as a photocatalyst is proposed to decompose water under ultraviolet irradiation in Honda and Fuji islands as early as 1972. Since then, photocatalytic technology has become an effective solution for wastewater treatment due to its economic, efficient, and environmental-friendly characteristics.

Some existing oxide semiconductor materials (such as TiO)₂ZnO) have been used in the field of photocatalysis, some researchers have been on TiO₂Modified and non-TiO₂More effort has been made in the research of semiconductors. However, the band gap of these oxide semiconductors is higher than 3.0 eV: therefore, they can only be activated under ultraviolet light, which accounts for less than 5% of the solar spectrum. Specifically, under the same conditions, the photocatalyst with a larger band gap has a lower utilization rate of the solar spectrum. With the further understanding of semiconductor materials and photocatalytic mechanisms, semiconductor materials are in the field of photocatalysisThe application has made a long-term progress and also makes a contribution to environmental protection and energy conservation.

At present, people research semiconductor photocatalysts with different crystal surfaces, and prove that the semiconductor photocatalysts with different crystal surfaces can generate different electronic structures, so that different energy band levels are caused. More importantly, the band level of a semiconductor material directly affects its photocatalytic performance. Thus, from [ Bi₂O₂]²⁺Laminated between two X^-The Bi-based thin film photocatalyst having a layered structure between ions attracts attention of many researchers due to its unique electronic structure. In particular, BiOX (X ═ Cl, Br, I) has excellent photocatalytic performance and application prospects, and has been widely studied. BiOX is proved to be an ideal carrier for heterogeneous catalytic reaction due to the advantages of visible light response, high chemical stability and the like. In order to further improve the photocatalytic performance and visible light response of the semiconductor material, the semiconductor photocatalytic material is synthesized by adopting 3d Transition Metals (TMs) and rare earth atoms doped with BiOX. Doping can create vacancies or defects, altering the energy gap of the BiOX (X ═ Cl, Br, I), thereby altering the intrinsic properties of the material through redistribution of electrons. Doping impurity atoms can provide impurity energy levels and alter the charge transfer characteristics of the material, thereby improving the performance of certain catalytic reactions.

Von et al prepared BiOBr three-dimensional microspheres by a simple solvothermal method, and found that they have a strong photolysis capability under ultraviolet light and visible light. Hu et al successfully synthesized Bi by hydrothermal method_1-xCe_xAnd (4) OBr. The results show that with Ce³⁺The appearance of the sample is gradually changed by increasing the doping concentration. In addition, a blue shift was detected in the samples and their band gaps increased. Liu et Al synthesized different Al by simple solvothermal method³⁺Bi of content_1-xAl_xAnd (4) OBr. Due to the separation of the photo-generated electron-hole pairs and the increase of the BET specific surface area, the photocatalytic performance is improved. The titanium-doped BiOBr photocatalyst is prepared by a double-component method, and the photocatalytic performance of a sample is improved by increasing the BET specific surface area. YIn et al prepared by doping La³⁺BiOBr of (1). The high photocatalytic performance of the samples is attributed to the narrow forbidden band and electron holesSeparation, and the hole as the main active material. Liu et al synthesized Fe by solvothermal decomposition method³⁺Ions and Er³⁺Ion co-doped uniform porous Bi₅O₇I (BiOI) microspheres. Yuan et al prepared successful Fe (III) -modified BiOBr by a simple one-step process. They believe that the presence of hydrogen peroxide enhances the photocatalytic degradation capability of the organic dye and the oxidizing capability of benzyl alcohol. Liu et al synthesized Fe based on Jace micromotor³⁺Doped BiOBr, and explains that under mild pH conditions and H₂O₂Excellent photocatalytic performance at concentration. Yellow et al synthesized Fe by one-step solvothermal method³⁺Modified layered bioceramic micro-flowers, degraded gaseous acetaldehyde indicating Fe³⁺The photocatalytic activity of the modified biological ceramic is greatly improved. Although there has been a lot of research work on bismuth oxyhalide, and solvothermal method, hydrothermal method, two-component method and one-step method are mostly adopted for synthesizing bismuth oxyhalide materials, the methods have limited effective reaction within a certain time and require longer time to complete the growth process of the materials.

Disclosure of Invention

The invention aims to provide a metal ion co-doped microsphere prepared by a microwave hydrothermal method and application thereof.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a metal ion co-doped BiOBr microsphere, which is particularly Bi_1-x-yCd_xFe_yOBr, where x ═ y ═ 0.02, or Bi_1-xCd_xOBr, where x is 0.02, or Bi_1-xFe_xOBr, where x is 0.02.

The invention also provides a preparation method of the metal ion co-doped BiOBr microsphere, which comprises the following steps:

(1) respectively dissolving a bismuth source and CTAB in an organic solvent, carrying out ultrasonic treatment, and carrying out magnetic stirring;

(2) mixing the two solutions, stirring to obtain precursor solution, adding 2 wt% Cd (NO) into the precursor solution₃)₂·4H₂O to obtain a mixed solution, and mixingTransferring the solution into a high-pressure autoclave with a polytetrafluoroethylene lining, adding a rupture membrane, and placing the high-pressure autoclave in a microwave hydrothermal reactor system for reaction;

(3) after the reaction is finished, cooling the product to room temperature, washing the product for a plurality of times by deionized water, fully washing the product by ethanol, and drying the product to obtain a product Bi_1-xCd_xOBr; 2 wt% Cd (NO) in step (2)₃)₂·4H₂Replacement of O (0.01542g) to 2 wt% Fe (NO)₃)₃·9H₂O, product Bi obtained_1-xFe_xOBr; 2 wt% Cd (NO) in step (2)₃)₂·4H₂Continuously adding 2 wt% Fe (NO) based on O₃)₃·9H₂O to obtain a product Bi_1-x-yCd_xFe_yOBr。

As a further improvement of the invention, the bismuth source in the step (1) is soluble bismuth salt. The soluble bismuth salt is preferably Bi (NO)₃)₃·5H₂O。

As a further improvement of the invention, in the step (1), the molar ratio of the bismuth source to CTAB is (1-3): (1-3).

As a further improvement of the present invention, the organic solvent is ethylene glycol.

As a further improvement of the invention, the final temperature of the microwave reaction in the step (2) is 180 ℃, wherein the heating time of the 0-60 ℃ temperature-raising stage is 3min, the heating time of the 60-120 ℃ temperature-raising stage is 3min, the heating time of the 120-180 ℃ temperature-raising stage is 3min, and the heating time of the 180-180 ℃ holding stage is 15 min.

As a further improvement of the invention, the drying temperature in the step (3) is 60-80 ℃ for 10-15 h.

The invention also provides a composite photocatalyst prepared by metal ion co-doping BiOBr microspheres.

The invention also provides application of the composite photocatalyst in wastewater treatment.

In the application process of treating wastewater, the addition amount of the composite photocatalyst is 50mg per 50ml of rhodamine B solution.

The invention discloses the following technical effects:

the Eg of Cd-doped BiOBr is smaller than the forbidden bandwidth (Eg) of pure BiOBr, and the fermi level of Cd is lower than that of BiOBr, so that photo-generated electrons can spontaneously move towards Cd due to the formation of schottky barrier. Second, photo-generated electrons are transferred to Bi_1-x-yCd_xFe_yThe OBr surface participates in the reduction reaction. Third, the substitution of the Fe atoms for the Bi atoms into the BiOBr lattice with metastable Fe³⁺In the form of ions. At the same time, Fe³⁺Ions capture photo-generated electrons and holes in the photocatalysis process to further form Fe²⁺And Fe⁴⁺Ions. However, Fe with 6 and 4 electrons in three-dimensional orbitals²⁺And Fe⁴⁺The ions are not stable in the catalytic system. Thus, Fe²⁺And Fe⁴⁺Trapped charges are easily released and transferred to Bi_1-x-yCd_xFe_yThe OBr surface participates in the catalytic reaction. In Bi_1-x-yCd_xFe_yOBr surface, Fe²⁺Oxidative conversion of ions to metastable Fe³⁺Ions. Oxygen radicals can be converted from oxygen by gaining electrons. At the same time, Fe⁴⁺Conversion of ions to metastable Fe³⁺Ions. In the catalytic system, the trapped holes play an essential role in the decomposition of the RhB dye. Thereby separating electrons from holes, and since the hole concentration is higher, in Bi_1-x-yCd_xFe_yThe OBr surface forms more hydroxyl radicals. More superoxide radicals can be formed due to photo-generated electrons. The newly emerging hydroxyl radicals and superoxide radicals will further promote the degradation of RhB. Notably, the hydroxyl radical is more positive than the HOMO of RhB, but more negative than the hole of VB in the photocatalyst. Therefore, hydroxyl radicals prefer to trap holes from VB. The electrons in the CB can induce the formation of photogenerated hydroxyl radicals. Thus, Cd²⁺And Fe³⁺The ion synergistic effect reduces the forbidden bandwidth of the BiOBr photocatalyst and provides an impurity energy level for electron transition. The results indicate that electrons and holes can be efficiently separated and participate in the photocatalytic reaction.

The invention utilizes the rapid reaction of microwave, selective heating and ultrasonic waveThe method has the advantages of improving molecular motion under a high-pressure system and the like, realizing the synergistic treatment of microwaves and ultrasonic waves under the high-pressure system, promoting the full reaction of raw materials in a short time, and reducing the influence generated in the reaction process as much as possible. For the reaction of doping bismuth oxyhalide with metal ions, the microwave hydrothermal reaction can efficiently promote the ions to obtain high energy to enter the crystal lattice of the bismuth oxyhalide to replace metal Bi in situ³⁺Ions form a stable structure through interaction between chemical bonds in a high-energy reaction system.

The invention adopts a microwave hydrothermal method to synthesize Cd²⁺/Fe³⁺And co-doping the uniform flower-shaped microsphere BiOBr photocatalyst assembled by the ultrathin nanosheets. Bi_1-xCd_xOBr and Bi_1-xThe degradation rate constants of FexOBr for RhB were 1.31 times and 2.05 times, respectively, that of pure BiOBr. In addition, novel Cd²⁺/Fe³⁺Codoping BiOBr photocatalyst in Cd²⁺And Fe³⁺Under the synergistic action of ions, the photocatalytic activity is obviously improved by enhancing the separation of photo-generated electrons/holes and a narrow band gap, and is about 3.10 times of that of pure BiOBr. By Cd²⁺And Fe³⁺The ion synergistic effect of the compounds widens the visible light response range and improves the photocatalysis process. Based on DFT theory, Fe with different valence states is systematically researched³⁺Conversion of ions promotes superoxide radical (. O)₂ ^-) Production of Cd²⁺The photodegradation mechanism of ions as electron transfer media illustrates the superoxide radical (. O)₂ ^-) And a cavity (h)⁺ _VB) Mainly participates in catalytic reaction. The reasonability of the experimental result is further proved by the reasonable growth mechanism and the catalysis mechanism, and the synergistic effect of the multi-ion doping has great potential in the field of photocatalysis.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic diagram of the degradation experiment;

FIG. 2 shows Bi prepared in example 1_0.98Cd_0.02Scanning electron microscope image of OBr under 11.63K magnification;

FIG. 3 shows Bi prepared in example 1_0.98Cd_0.02Scanning electron microscope images of OBr at 35.00K magnification;

FIG. 4 shows Bi prepared in example 2_0.98Fe_0.02Scanning electron microscope images of OBr at 13.59K magnification;

FIG. 5 shows Bi prepared in example 2_0.98Fe_0.02Scanning electron microscope images of OBr at 41.76K magnification;

FIG. 6 shows Bi prepared in example 3_0.96Cd_0.02Fe_0.02Scanning electron microscope image of OBr under 11.63K magnification; (ii) a

FIG. 7 shows Bi prepared in example 3_0.96Cd_0.02Fe_0.02Scanning electron microscope image of OBr under 22.85K magnification;

FIG. 8 is a scanning electron micrograph of BiOBr microspheres prepared in example 4 at 16.11K magnification;

FIG. 9 is a scanning electron micrograph of BiOBr microspheres prepared in example 4 at 30.00K magnification;

FIG. 10 is a degradation diagram of rhodamine B, wherein FIG. 10a is a diagram of the BiOBr prepared in example 4 degrading rhodamine B, and B is a diagram of the Bi prepared in example 1_0.98Cd_0.02FIG. of degrading rhodamine B by OBr, c is Bi prepared in example 2_0.98Fe_0.02FIG. of degrading rhodamine B by OBr, d is Bi prepared in example 3_0.96Cd_0.02Fe_0.02And degrading the rhodamine B by using OBr.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.