阅读说明：本技术 一种二氧化铈-氧化锌-卤氧化铋-铁酸钴磁性可见光催化剂制备方法 (Preparation method of cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst ) 是由 张安超 周普阳 张立享 朱贞卫 张新民 张丹 李海霞 陈国艳 于 2020-06-10 设计创作，主要内容包括：本发明提供一种二氧化铈-氧化锌-卤氧化铋-铁酸钴磁性可见光催化剂制备方法,包括：制备铁酸钴磁性微颗粒；制备二氧化铈-氧化锌微颗粒；根据铁酸钴和二氧化铈-氧化锌,制备磁性可见光催化剂二氧化铈-氧化锌-卤氧化铋-铁酸钴；其中,X为氯元素、溴元素或碘元素。本发明所述二氧化铈-氧化锌-卤氧化铋-铁酸钴磁性可见光催化剂制备方法比较简单、成本低廉,而且本发明所述制备方法制备的二氧化铈-氧化锌-卤氧化铋-铁酸钴磁性可见光催化剂具有环境友好、成本低廉、光催化氧化活性高等特点,可广泛应用于大气污染防治领域。(The invention provides a preparation method of a cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst, which comprises the following steps: preparing cobalt ferrite magnetic microparticles; preparing ceria-zinc oxide microparticles; preparing a magnetic visible light catalyst cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite according to cobalt ferrite and cerium dioxide-zinc oxide; wherein, X is chlorine element, bromine element or iodine element. The preparation method of the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-induced photocatalyst is simple and low in cost, and the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-induced photocatalyst prepared by the preparation method has the characteristics of environmental friendliness, low cost, high photocatalytic oxidation activity and the like, and can be widely applied to the field of air pollution prevention and control.)

1. A preparation method of a cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst is characterized by comprising the following steps:

step 1, preparing cobalt ferrite CoFe₂O₄Microparticles;

step 2, preparing cerium dioxide-zinc oxide CeO₂-ZnO microparticles;

step 3, preparing cobalt ferrite CoFe according to the step 1₂O₄And step 2, the prepared cerium dioxide-zinc oxide CeO₂Preparing magnetic visible light catalyst cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite CeO by using ZnO₂-ZnO-BiOX-CoFe₂O₄(ii) a Wherein, X is chlorine element, bromine element or iodine element.

2. The method for preparing the ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst according to claim 1, wherein the step 1 specifically comprises the following steps:

step 11, a mol of cobalt nitrate hexahydrate Co (NO)₃)₂·6H₂O and 2a moles of iron nitrate nonahydrate Fe (NO)₃)₃·9H₂Dissolving O in deionized water and uniformly stirring to obtain a first solution containing cobalt nitrate and ferric nitrate; wherein a is a real number;

step 12, dissolving 8a mol of sodium hydroxide into deionized water to obtain a sodium hydroxide solution;

step 13, slowly adding a sodium hydroxide solution into the first solution under the action of a mechanical electric stirrer, keeping the pH value of the first solution added with the sodium hydroxide between 12 and 14, and then continuously stirring for 2 hours to obtain a second solution containing suspended particles;

step 14, placing the second solution in a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 12 hours at the heating temperature of 180 ℃ to obtain a third solution containing precipitates;

step 15, after the third solution is naturally cooled to room temperature, taking out the precipitate in the third solution, washing the precipitate for 3-5 times, and then placing the washed precipitate in an oven at 80 ℃ for vacuum drying for 24 hours to obtain a first dried product;

step 16, grinding and screening the first dried product in sequence to obtain cobalt ferrite CoFe₂O₄Microparticles.

3. The method for preparing the ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst according to claim 2, wherein the step 2 specifically comprises the following steps:

step 21, adding b moles of zinc acetate dihydrate Zn (CH)₃COO)₂·2H₂O and (0.0473-0.473) b moles of cerium nitrate Ce (NO) hexahydrate₃)₃·6H₂Dissolving O in absolute ethyl alcoholContinuing ultrasonic oscillation for 2 hours to obtain a fourth solution containing zinc acetate and cerium nitrate; wherein b is a real number;

step 22, placing the fourth solution in an oven at 80 ℃ for vacuum drying for 24-48 hours to obtain a viscous first solid product;

step 23, placing the first solid product in a muffle furnace for calcining: heating to 400 ℃ within 60 minutes and preserving the temperature for 2 hours to obtain a powdery calcined product;

step 24, sequentially grinding and screening the calcined product to obtain cerium dioxide-zinc oxide CeO₂-ZnO microparticles.

4. The method for preparing the ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst according to claim 3, wherein the ceria-zinc oxide CeO₂In the micro-particles of ZnO, cerium oxide CeO₂The mass ratio of the zinc oxide to the ZnO is 0.1-1.0; wherein, the unit of mass is gram, and the mass ratio is dimensionless.

5. The method for preparing the ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst according to claim 3, wherein the step 3 specifically comprises the following steps:

step 31, dissolving c mol of bismuth nitrate pentahydrate into an aqueous solution containing glacial acetic acid, and uniformly stirring to obtain a bismuth nitrate solution under an acidic condition; wherein c is a real number;

step 32, mixing (0.055-0.750) c mol of cobalt ferrite CoFe₂O₄Magnetic microparticles and (2.605-70.380) c moles of cerium oxide-zinc oxide CeO₂Adding ZnO microparticles into a bismuth nitrate solution under an acidic condition, and continuously stirring for 30 minutes under the action of a mechanical electric stirrer to obtain a fifth solution;

step 33, under the action of a mechanical electric stirrer, dropwise adding the c-mol potassium halide KX solution into the fifth solution, continuously stirring for 2 hours, and standing for 12 hours to obtain a second solid product;

step 34, washing the second solid product for 3-5 times by using a mixed solution of deionized water and ethanol, and then placing the washed second solid product in an oven at the temperature of 60-70 ℃ for vacuum drying for 24-48 hours to obtain a second dried product;

step 35, grinding and screening the second dried product in sequence to obtain the magnetic visible light catalyst cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite CeO₂-ZnO-BiOX-CoFe₂O₄。

6. The method for preparing the ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst as claimed in claim 5, wherein the magnetic visible-light-driven photocatalyst ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite CeO₂-ZnO-BiOX-CoFe₂O₄Medium, cobalt ferrite CoFe₂O₄The mass ratio of the bismuth oxyhalide to the bismuth oxyhalide BiOX is 0.05-0.5; ceria-zinc oxide CeO₂The mass ratio of the-ZnO compound to the bismuth oxyhalide BiOX is 0.01-0.2; ceria-zinc oxide CeO₂In the ZnO composite, cerium oxide CeO₂The mass ratio of the zinc oxide to the ZnO is 0.1-1.0.

7. The preparation method of the ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst according to claim 4, wherein in the step 31, the pH value of the bismuth nitrate solution under acidic conditions is 2-5.

8. The method for preparing the ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst as claimed in claim 2, wherein in step 13, the suspended particles are cobalt hydroxide and iron hydroxide; in step 14, the precipitate is cobalt ferrite.

Technical Field

The invention relates to pollution prevention technology, in particular to a preparation method of a cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst.

Background

Currently, mercury pollution has attracted a wide range of attention worldwide for its highly harmful nature. In actual production life, coal-fired power plants are the main source of artificial mercury emission. In China, about 38% of mercury pollution is related to coal burning. The mercury in the coal-fired flue gas is mainly elemental mercury Hg⁰Hg of bivalent mercury²⁺And particulate mercury Hg^pThree forms exist; wherein, the elementary mercury Hg⁰Low melting point, easy volatilization and difficult water solubility, and divalent mercury Hg²⁺And particulate mercury Hg^pIn contrast, elemental mercury Hg⁰More difficult to remove from the flue gas.

There are four main methods for mercury removal: the first is an adsorption method which adsorbs mercury using activated carbon or the like; but the adsorption capacity is limited, so the material cannot be used for a long time and is expensive; furthermore, the activated carbon injection technique also affects the value of fly ash recycling. The second is catalytic oxidation, i.e. metal oxides with HCl or O₂Combining elemental mercury Hg⁰Catalytic oxidation to divalent mercury Hg²⁺The post-absorbed liquid is removed, the method needs to additionally add a demercuration device, so the operation cost of the coal-fired power plant is increased, and the used catalysis isAgent placement is also a problem to be solved. The third method is a method using conventional pollutant removal equipment, and the method can remove bivalent mercury Hg by using a wet desulphurization and dust removal device²⁺And particulate mercury Hg^pHowever, this method is on Hg⁰The removal effect is very little. The fourth method is a method using a photocatalyst, which can excite and generate photo-generated electron-hole pairs e under the irradiation of visible light or ultraviolet light^--h⁺The photo-generated electron hole pairs can react with oxygen or water adsorbed on the surface of the photocatalyst to generate superoxide radical ions^·O₂ ^-Or hydroxy^·OH to remove elemental mercury Hg⁰(ii) a But the activity of the photo-generated electron hole pair is lower, the preparation cost of the photocatalyst is higher, and the recovery is difficult.

Therefore, in the prior art, the flue gas demercuration method has the problems of poor demercuration effect, high cost, complex operation and maintenance and the like.

Disclosure of Invention

In view of the above, the main object of the present invention is to provide a method for preparing a ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible light catalyst with good mercury removal effect, low cost and simple operation and maintenance.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the preparation method of the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-driven photocatalyst comprises the following steps:

step 1, preparing cobalt ferrite CoFe₂O₄Microparticles.

Step 2, preparing cerium dioxide-zinc oxide CeO₂-ZnO microparticles.

Step 3, preparing cobalt ferrite CoFe according to the step 1₂O₄And step 2, the prepared cerium dioxide-zinc oxide CeO₂Preparing magnetic visible light catalyst cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite CeO by using ZnO₂-ZnO-BiOX-CoFe₂O₄(ii) a Wherein, X is chlorine element, bromine element or iodine element.

In summary, the preparation method of the ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible light catalyst provided by the invention provides a ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible light catalyst for removing elemental mercury in flue gas by a wet method, under the irradiation of visible light, the efficiency of the catalyst on the photocatalytic oxidation demercuration of elemental mercury is as high as more than 90%, and the magnetic visible light catalyst has strong magnetic recovery capacity and can be used for multiple times. The preparation method of the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-induced photocatalyst is simple and low in cost, and the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-induced photocatalyst prepared by the preparation method has the characteristics of environmental friendliness, low cost, high photocatalytic oxidation activity and the like.

Drawings

FIG. 1 is a general flow chart of the preparation method of the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible light catalyst according to the present invention.

FIG. 2 shows the preparation of cobalt ferrite CoFe according to the present invention₂O₄Is a schematic flow diagram.

FIG. 3 shows the preparation of cerium oxide-zinc oxide CeO according to the present invention₂Schematic flow diagram of ZnO.

FIG. 4 is a schematic diagram of a process for preparing a magnetic visible-light-driven photocatalyst, namely ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite.

FIG. 5 is a schematic diagram of the overall structure of the experimental bench used in the embodiment of the preparation method of the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible light catalyst.

Fig. 6 is a diagram of the demercuration efficiency obtained by using each magnetic visible-light-driven photocatalyst for demercuration in example three of the present invention.

FIG. 7 is a diagram showing the measurement results of the hysteresis loop in the preparation method of the cerium dioxide-zinc oxide-bismuth oxyiodide-cobalt ferrite magnetic visible-light-induced photocatalyst according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a general flow chart of the preparation method of the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible light catalyst according to the present invention. As shown in fig. 1, the preparation method of the ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible light catalyst according to the present invention comprises the following steps:

step 1, preparing cobalt ferrite CoFe₂O₄Microparticles.

Step 2, preparing cerium dioxide-zinc oxide CeO₂-ZnO microparticles.

Step 3, preparing cobalt ferrite CoFe according to the step 1₂O₄And step 2, the prepared cerium dioxide-zinc oxide CeO₂Preparing magnetic visible light catalyst cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite CeO by using ZnO₂-ZnO-BiOX-CoFe₂O₄(ii) a Wherein, X is chlorine element, bromine element or iodine element.

In a word, the preparation method of the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible light catalyst provides the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible light catalyst for removing the elemental mercury in the flue gas by a wet method, the catalyst has the photocatalytic oxidation demercuration efficiency of the elemental mercury up to over 90 percent under the irradiation of visible light, and the magnetic visible light catalyst has strong magnetic recovery capacity and can be used for multiple times. The preparation method of the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-induced photocatalyst is simple and low in cost, and the cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite magnetic visible-light-induced photocatalyst prepared by the preparation method has the characteristics of environmental friendliness, low cost, high photocatalytic oxidation activity and the like.

FIG. 2 shows the preparation of cobalt ferrite CoFe according to the present invention₂O₄Is a schematic flow diagram. As shown in fig. 2, in the present invention, the step 1 specifically includes the following steps:

step 11, a mol of cobalt nitrate hexahydrate Co (NO)₃)₂·6H₂O and 2a moles of iron nitrate nonahydrate Fe (NO)₃)₃·9H₂Dissolving O in deionized water and stirringAfter the mixture is uniform, obtaining a first solution containing cobalt nitrate and ferric nitrate; wherein a is a real number.

And step 12, dissolving 8a mol of sodium hydroxide into deionized water to obtain a sodium hydroxide solution.

And step 13, slowly adding the sodium hydroxide solution into the first solution under the action of a mechanical electric stirrer, keeping the pH value of the first solution added with the sodium hydroxide between 12 and 14, and then continuously stirring for 2 hours to obtain a second solution containing suspended particles. In the invention, the suspended particles are cobalt hydroxide and iron hydroxide which are generated by corresponding cobalt ions, iron ions and hydroxide radicals.

And step 14, placing the second solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 12 hours at the heating temperature of 180 ℃ to obtain a third solution containing precipitates. In the invention, the precipitate is cobalt hydroxide and cobalt ferrite obtained by oxidizing ferric hydroxide.

Step 15, after the third solution is naturally cooled to room temperature, washing the precipitate taken out of the third solution for 3-5 times by using a mixture of absolute ethyl alcohol and water, and then placing the washed precipitate in an oven at 80 ℃ for vacuum drying for 24 hours to obtain a first dried product;

step 16, grinding and screening the first dried product in sequence to obtain cobalt ferrite CoFe₂O₄Microparticles.

FIG. 3 shows the preparation of cerium oxide-zinc oxide CeO according to the present invention₂Schematic flow diagram of ZnO microparticles. As shown in fig. 3, in the present invention, the step 2 specifically includes the following steps:

step 21, adding b moles of zinc acetate dihydrate Zn (CH)₃COO)₂·2H₂O and (0.0473-0.473) b moles of cerium nitrate Ce (NO) hexahydrate₃)₃·6H₂Dissolving O in absolute ethyl alcohol, and then continuing ultrasonic oscillation for 2 hours to obtain a fourth solution containing zinc acetate and cerium nitrate; wherein b is a real number.

And step 22, placing the fourth solution in an oven at 80 ℃ for vacuum drying for 24-48 hours to obtain a viscous first solid product.

Step 23, placing the first solid product in a muffle furnace for calcining: the temperature was raised to 400 ℃ within 60 minutes and held for 2 hours to obtain a powdery calcined product.

Step 24, sequentially grinding and screening the calcined product to obtain cerium dioxide-zinc oxide CeO₂-ZnO microparticles.

In the present invention, ceria-zinc oxide CeO₂In the micro-particles of ZnO, cerium oxide CeO₂The mass ratio of the zinc oxide to the ZnO is 0.1-1.0; wherein, the unit of mass is gram, and the mass ratio is dimensionless.

FIG. 4 is a schematic diagram of a process for preparing a magnetic visible-light-driven photocatalyst, namely ceria-zinc oxide-bismuth oxyhalide-cobalt ferrite. As shown in fig. 4, step 3 of the present invention specifically includes the following steps:

step 31, dissolving c mol of bismuth nitrate pentahydrate into an aqueous solution containing glacial acetic acid, and uniformly stirring to obtain a bismuth nitrate solution under an acidic condition; wherein c is a real number.

In the invention, the pH value of the bismuth nitrate solution under the acidic condition is 2-5.

Step 32, mixing (0.055-0.750) c mol of cobalt ferrite CoFe₂O₄Magnetic microparticles and (2.605-70.380) c moles of cerium oxide-zinc oxide CeO₂And adding ZnO microparticles into the bismuth nitrate solution under the acidic condition, and continuously stirring for 30 minutes under the action of a mechanical electric stirrer to obtain a fifth solution.

And step 33, dropwise adding the c mol potassium halide KX solution into the fifth solution under the action of a mechanical electric stirrer, continuously stirring for 2 hours, and standing for 12 hours to obtain a second solid product.

And step 34, washing the second solid product for 3-5 times by using a mixed solution of deionized water and ethanol, and then placing the washed second solid product in an oven at the temperature of 60-70 ℃ for vacuum drying for 24-48 hours to obtain a second dried product.

Step 35, grinding and screening the second dried product in sequence to obtain the magnetic visible light catalyst cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite CeO₂-ZnO-BiOX-CoFe₂O₄。

The magnetic visible-light-driven photocatalyst of the invention is cerium dioxide-zinc oxide-bismuth oxyhalide-cobalt ferrite CeO₂-ZnO-BiOX-CoFe₂O₄Medium, cobalt ferrite CoFe₂O₄The mass ratio of the bismuth oxyhalide to the bismuth oxyhalide BiOX is 0.05-0.5; ceria-zinc oxide CeO₂The mass ratio of the-ZnO compound to the bismuth oxyhalide BiOX is 0.01-0.2; ceria-zinc oxide CeO₂In the ZnO composite, cerium oxide CeO₂The mass ratio of the zinc oxide to the ZnO is 0.1-1.0.

In the invention, the amounts of the deionized water, the ethanol and the glacial acetic acid can be determined according to actual requirements.