阅读说明：本技术 一种石墨烯负载碘酸氧铋光催化剂及其制备方法与应用 (Graphene-loaded bismuth oxyiodide photocatalyst and preparation method and application thereof ) 是由 吴江 凌杨 罗非 刘启贞 毛旭 王崇洋 刘海龙 何平 马昕霞 朱凤林 于 2019-11-08 设计创作，主要内容包括：本发明提供一种石墨烯负载碘酸氧铋光催化剂及其制备方法应用。其制备包括：将五水硝酸铋加入去离子水中并持续磁力搅拌；称取一定量的碘酸钾置入上述混合物中,并继续磁力搅拌；将上述的混合物放置于水热反应釜中,进行水热反应得到反应产物；将上述反应产物用去离子水和无水乙醇分别洗涤并烘干,得到固体样品；将上述固体样品以一定比例与石墨烯复合即得石墨烯负载碘酸氧铋光催化剂。本发明的石墨烯负载碘酸氧铋光催化剂,具有较高的比表面积和优异的光催化性能。(The invention provides a graphene-loaded bismuth oxyiodate photocatalyst and a preparation method and application thereof. The preparation method comprises the following steps: adding bismuth nitrate pentahydrate into deionized water and continuously stirring by magnetic force; weighing a certain amount of potassium iodate, putting the potassium iodate into the mixture, and continuing to stir by magnetic force; placing the mixture in a hydrothermal reaction kettle, and carrying out hydrothermal reaction to obtain a reaction product; washing and drying the reaction product by using deionized water and absolute ethyl alcohol respectively to obtain a solid sample; and compounding the solid sample with graphene according to a certain proportion to obtain the graphene-supported bismuth oxyiodate photocatalyst. The graphene-supported bismuth oxyiodate photocatalyst disclosed by the invention has a relatively high specific surface area and excellent photocatalytic performance.)

1. A preparation method of a graphene-supported bismuth oxyiodate photocatalyst is characterized by comprising the following steps:

step 1: dissolving bismuth nitrate pentahydrate in deionized water, and uniformly stirring by magnetic force to obtain a solution A;

step 2: dissolving potassium iodate in the solution A prepared in the step 1, and uniformly stirring by magnetic force to prepare a solution B;

and step 3: placing the solution B in a hydrothermal reaction kettle, carrying out hydrothermal reaction for 8-12 h at the temperature of 160-200 ℃, then respectively washing with deionized water and absolute ethyl alcohol for several times, drying in an oven at the temperature of 80-90 ℃ for 12-18 h, and grinding to obtain bismuth oxyiodate powder;

and 4, step 4: dissolving the bismuth oxyiodate powder prepared in the step 3 in deionized water, and uniformly stirring by magnetic force to prepare a solution C;

and 5: dissolving graphene in the solution C prepared in the step 4, and uniformly stirring by magnetic force to prepare a solution D;

step 6: and (3) placing the solution D prepared in the step (5) in a hydrothermal reaction kettle, carrying out hydrothermal reaction for 8-12 h at the temperature of 160-200 ℃, then respectively washing with deionized water and absolute ethyl alcohol for several times, drying in an oven at the temperature of 80-90 ℃ for 12-18 h, and grinding to obtain the graphene-loaded bismuth oxyiodide photocatalyst.

2. The method for preparing the graphene-supported bismuth oxyiodate photocatalyst according to claim 1, wherein the concentration of bismuth nitrate in the solution A in the step 1 is 125 mmol/L.

3. The method for preparing the graphene-supported bismuth oxyiodate photocatalyst according to claim 1, wherein the molar ratio of potassium iodate to bismuth nitrate in the solution B in the step 2 is 1: 1.

4. The method for preparing the graphene-supported bismuth oxyiodate photocatalyst as claimed in claim 1, wherein the concentration of bismuth oxyiodate in the solution C in the step 4 is 0.0125 g/mL.

5. The preparation method of the graphene-supported bismuth oxyiodate photocatalyst according to claim 1, wherein the mass ratio of graphene to bismuth oxyiodate in the solution D in the step 4 is 1: 1-1: 10.

6. The graphene-supported bismuth oxyiodate photocatalyst prepared by the method of any one of claims 1 to 5.

7. The application of the graphene-supported bismuth oxyiodate photocatalyst prepared by the method of any one of claims 1 to 5 in the field of photocatalysis.

8. The application of the graphene-supported bismuth oxyiodate photocatalyst in the field of photocatalysis as claimed in claim 7, wherein the application comprises photocatalytic oxidation of elemental mercury and photocatalytic reduction of carbon dioxide.

Technical Field

The invention belongs to the field of bismuth-based composite materials, and particularly relates to a graphene-loaded bismuth oxyiodate photocatalyst and a preparation method and application thereof.

Background

The economic development can not be separated from the input of energy, and the energy supply of China mainly comprises coal for a long time. Coal occupies a great position in national economic development, and currently occupies about 70% of primary energy consumption. The combustion of coal is accompanied by the emission of large amounts of air pollutants. Taking a thermal power plant as an example, common smoke pollutants include sulfur dioxide, nitrogen oxides, dust, heavy metal pollutants, and the like. The discharge of these pollutants has a bad influence on the ecological environment and poses a threat to the production and living environment of human beings. The development of a high-efficiency and low-cost pollutant control technology becomes a key scientific problem and is widely concerned by researchers at home and abroad in recent years.

Taking heavy metal mercury pollution in coal-fired flue gas as an example, the heavy metal mercury pollution mainly contains three forms including simple substance mercury, oxidation state mercury and particle state mercury. Wherein the oxidized mercury is easily dissolved in water and can be jointly removed by combining a limestone-gypsum Wet Flue Gas Desulfurization (WFGD) system. The particulate mercury can be captured by a conventional dust collector, such as a bag filter (FF) or an electrostatic precipitator (ESP). In contrast, elemental mercury, chemically stable, is insoluble in water and is difficult to remove effectively by existing Air Pollution Control Devices (APCDs). The elemental mercury has great influence on the ecological environment, can exist in the atmosphere for 1-2 years, cannot be degraded by microorganisms, is easy to enrich in organisms and convert into highly toxic metal organic compounds, and causes serious harm to human health.

The development of an efficient heavy metal mercury pollutant removal technology becomes a hot problem. The common methods at present are an adsorption method and an oxidation method. The adsorption method adopts the injection of an adsorbent in a hearth to try to adsorb and fix mercury pollutants in the flue gas. However, as mercury is deposited, the active sites on the sorbent surface will be occupied by mercury atoms resulting in sorbent breakthrough and failure to continuously reduce the mercury concentration in the flue gas. In practical application, the adsorbent needs to be continuously sprayed into the hearth. This changes the composition of the fly ash, which is not conducive to secondary utilization of the fly ash, and the cost of the method of spraying the adsorbent is too expensive to be popularized. In contrast, oxidation methods for oxidizing elemental mercury into oxidized mercury and combining with existing WFGD systems for combined removal of total mercury are increasingly favored by researchers.

The photocatalytic technology is an efficient and safe environment-friendly air purification technology, and the basic principle is that a photocatalyst is excited by irradiation of visible light or ultraviolet light to generate active groups such as photoproduction cavities, hydroxyl free radicals, superoxide free radicals and the like, and then reacts with target pollutants to achieve the purpose of catalytic degradation. In consideration of high-intensity ultraviolet radiation contained in an electrostatic precipitator (ESP) commonly equipped in a coal-fired power plant, photocatalytic oxidation of elemental mercury by adopting a photocatalytic technology becomes a feasible mercury removal scheme. The core of the photocatalysis technology lies in developing a photocatalyst with good selectivity and high efficiency. Bismuth oxyiodate (BiOIO)₃) The photocatalyst is a novel photocatalyst, has a unique Oliviz layered non-centrosymmetric structure, and has excellent electron transmission characteristics. In addition, due to bismuth oxyiodate (BiOIO)₃) The valence band position of the mercury is positive, and photoproduction holes generated by the excitation of illumination have stronger oxidability and can effectively oxidize elemental mercury. However, pure bismuth oxyiodate (BiOIO)₃) The crystal has a wide forbidden band width, cannot effectively absorb illumination in a visible light wavelength range, and limits the application of the crystal under the drive of visible light. In addition, pure bismuth oxyiodate (BiOIO)₃) The specific surface area of the crystal is small, which is not beneficial to the dispersion of active point positions, thereby reducing the collision probability of the catalyst surface and target pollutants and being not beneficial to the reaction. By graphene and bismuth oxyiodate (BiOIO)₃) Composite, shapeBismuth oxyiodide/graphene (BiOIO)₃the/Graphene) interface heterostructure can effectively reduce the forbidden bandwidth of a system and widen the photoresponse interval of the photocatalyst. The photo-generated electrons generated by excitation can be injected into the graphene, so that the recombination of photo-generated electron-hole pairs is hindered, the service life of a photo-generated carrier is prolonged, and the reaction of the generated free radicals and target pollutants is facilitated.

Disclosure of Invention

The invention aims to solve the technical problem that the mercury removal effect of the flue gas of coal burning is poor in the prior art, and provides a graphene-loaded bismuth oxyiodide photocatalyst and a preparation method thereof.

In order to solve the technical problem, the invention provides a preparation method of a graphene-supported bismuth oxyiodate photocatalyst, which is characterized by comprising the following steps of:

step 1: adding bismuth nitrate pentahydrate [ Bi (NO)₃)₃·5H₂O]Dissolving in deionized water, and magnetically stirring to obtain solution A;

step 2: mixing potassium iodate (KIO)₃) Dissolving the mixture in the solution A prepared in the step 1, and uniformly stirring the mixture by magnetic force to prepare a solution B;

and step 3: placing the solution B in a hydrothermal reaction kettle, carrying out hydrothermal reaction for 8-12 h at the temperature of 160-200 ℃, then respectively washing with deionized water and absolute ethyl alcohol for several times, drying in an oven for 12-18 h at the temperature of 80-90 ℃, and grinding to obtain bismuth oxyiodide (BiOIO)₃) Powder;

and 4, step 4: dissolving the bismuth oxyiodate powder prepared in the step 3 in deionized water, and uniformly stirring by magnetic force to prepare a solution C;

and 5: dissolving graphene in the solution C prepared in the step 4, and uniformly stirring by magnetic force to prepare a solution D;

step 6: and (3) placing the solution D prepared in the step (5) in a hydrothermal reaction kettle, carrying out hydrothermal reaction for 8-12 h at the temperature of 160-200 ℃, then respectively washing with deionized water and absolute ethyl alcohol for several times, drying in an oven at the temperature of 80-90 ℃ for 12-18 h, and grinding to obtain the graphene-loaded bismuth oxyiodide photocatalyst.

Preferably, the concentration of the bismuth nitrate in the solution A in the step 1 is 125 mmol/L.

Preferably, the molar ratio of the potassium iodate to the bismuth nitrate in the solution B in the step 2 is 1: 1.

Preferably, the concentration of bismuth oxyiodate in the solution C in the step 4 is 0.0125 g/mL.

Preferably, the mass ratio of the graphene to the bismuth oxyiodate in the solution D in the step 4 is 1: 1-1: 10.

The invention also provides the graphene-supported bismuth oxyiodate photocatalyst prepared by the method.

The invention also provides application of the graphene-supported bismuth oxyiodate photocatalyst prepared by the method in the field of photocatalysis.

Preferably, the application comprises: : photocatalytic oxidation of elemental mercury, photocatalytic reduction of carbon dioxide, and the like.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention utilizes bismuth oxyiodate (BiOIO)₃) The graphene is compounded with graphene, so that the forbidden bandwidth of a system is reduced, the photoresponse interval of the photocatalyst is widened, the service life of a photon-generated carrier can be effectively prolonged, and the reaction is promoted to be carried out.

(2) The graphene-supported bismuth oxyiodate photocatalyst provided by the invention can overcome the defects caused by the traditional titanium dioxide catalyst and relieve the defects of pure bismuth oxyiodate (BiOIO)₃) The crystal forbidden band width is too wide, and the specific surface area is small. The preparation method is simple in preparation process and high in repeatability.

Drawings

Fig. 1 is a Scanning Electron Microscope (SEM) image of the graphene supported bismuth oxyiodate photocatalyst obtained in example 1 of the present invention;

fig. 2 is a diagram of the efficiency of photocatalytic oxidation of elemental mercury by using a graphene-supported bismuth oxyiodide photocatalyst and pure bismuth oxyiodide obtained in example 2 of the present invention.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

The specifications of the reagents used in the present invention are shown in table 1.

TABLE 1