Preparation method and application of ultra-efficient nitrate radical activation catalyst

Abstract

A preparation method and application of an ultra-efficient nitrate-based free radical activation catalyst, the preparation method comprising the following steps: S1: dissolving bismuth nitrate Bi(NO3)3·5H2O and polyvinylpyrrolidone (PVP) in a mannitol solution; S2: adding potassium bromide to the solution in step S1, and ultrasonically treating the solution to form a white suspension; S3: transferring the suspension to a high-pressure reactor for hydrothermal reaction; S4: cooling after the reaction is completed, collecting the precipitate by centrifugation, washing, and vacuum freeze-drying to obtain bismuth oxybromide Bi(NO3)3·5H2O. x OBr nanosheet catalyst. The application of the ultra-efficient nitrate-based free radical activation catalyst in the degradation of organic pollutants is to x OBr nanosheet catalysts are added to nitrate-containing water, and their photoinduced deformation-induced piezoelectric effect is used to activate nitrate to produce free radicals without the need for an external electric field or oxidant, thereby degrading organic pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental functional materials, and in particular to a method for preparing an ultra-efficient nitrate free radical activation catalyst and its application in catalytic degradation of organic pollutants. Background Art

[0002] As the world pays increasing attention to environmental pollution and energy consumption, photocatalysis / piezoelectric catalysis technology, as a green and sustainable catalytic method, has attracted widespread attention in solving environmental problems. Piezoelectric catalysis technology has shown great potential in the application of environmental governance. Photoinduced deformation phenomenon refers to the deformation of the material structure under light conditions, which triggers its piezoelectric effect, and photopiezoelectric catalysis uses this effect to activate chemical reactions. In the field of pollutant degradation, photocatalytic technology has been widely studied, especially in the treatment of organic pollutants, such as the degradation of organophosphorus flame retardants. These chemicals pose a serious threat to the ecological environment and human health due to their toxicity and persistence. Therefore, the development of efficient photo / piezoelectric catalytic materials to activate nitrates to generate free radicals and then degrade organic pollutants has become an important direction in environmental remediation research.

[0003] Currently, traditional photocatalytic methods face challenges with low catalytic efficiency and slow reaction rates when treating organophosphorus pollutants. Photoelectricity can cause deformation in materials, thereby enhancing the material's piezoelectric effect, improving its electron transfer ability, and promoting the occurrence of reactions. During the nitrate activation process, the light-induced deformation effect can effectively promote the generation of highly active free radicals from nitrates, which can react with organic matter, thereby achieving its degradation. This type of reaction usually takes place under mild conditions, which can not only improve catalytic efficiency but also reduce byproducts and environmental pollution during the reaction process, making it an ideal green catalytic technology.

[0004] However, although the photoelectric-piezoelectric synergistic catalytic technology shows excellent application prospects, there are still certain technical bottlenecks. First, the selection and design of photocatalytic materials are crucial. The materials must have good photoinduced deformation properties and efficient photocatalytic performance. At present, researchers have designed some nanomaterials and composite materials, such as doping elements or modifying photocatalysts, to enhance the photoinduced deformation effect and catalytic activity of the materials. Secondly, the free radical generation mechanism and degradation pathway in the reaction system still need further study to achieve more efficient pollutant degradation. In addition, how to improve the stability and reusability of photocatalytic materials in practical applications is also an important topic in current research.

[0005] It should be noted that the information disclosed in the above background technology section is only used to understand the background of this application, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0006] The main purpose of the present invention is to overcome the defects in the above-mentioned background technology and provide a preparation method and application of an ultra-efficient nitrate free radical activation catalyst.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing an ultra-efficient nitrate free radical activation catalyst comprises the following steps:

[0009] S1: Dissolve bismuth nitrate Bi(NO3)3·5H2O and polyvinylpyrrolidone PVP in mannitol solution;

[0010] S2: adding potassium bromide (KBr) to the solution of step S1 and sonicating to form a white suspension;

[0011] S3: transferring the suspension to a high-pressure reactor for hydrothermal reaction;

[0012] S4: After the reaction is completed, cool the mixture, collect the precipitate by centrifugation, wash it, and freeze-dry it in a vacuum to obtain bismuth oxybromide Bi x OBr nanosheet catalyst.

[0013] Furthermore, in step S1, the following ratio is adopted: the amount of bismuth nitrate is within 50 mg, the molecular weight of PVP is 10000, the amount is within 5 g, the concentration of mannitol solution is within 0.2 M, and the volume is within 100 mL.

[0014] Furthermore, in step S1, magnetic stirring is performed for a period of no more than 60 minutes.

[0015] Furthermore, in step S2, the amount of potassium bromide used is within 1000 mg, and the ultrasonic treatment time is within 60 minutes.

[0016] Furthermore, in step S3, the temperature of the hydrothermal reaction is within 200° C. and the reaction time is within 3 hours.

[0017] Furthermore, in step S4, the vacuum freeze-drying time is within 50 hours.

[0018] Furthermore, in step S4, washing is performed with water and ethanol in sequence. The specific method of ethanol washing is: adding ethanol to the precipitate, centrifuging and removing the supernatant.

[0019] An application of the ultra-efficient nitrate-based free radical activation catalyst in the degradation of organic pollutants, wherein the bismuth oxygen bromide Bi xOBr nanosheet catalysts are added to nitrate-containing water, and their photoinduced deformation-induced piezoelectric effect is used to activate nitrate to produce free radicals without the need for an external electric field or oxidant, thereby degrading organic pollutants.

[0020] Furthermore, 10-100 mg Bi x The OBr nanocatalyst was added to 200 mL of a solution containing nitrate and organic pollutants; the nitrate was potassium nitrate with a concentration of 0-100 mg / L; the organic pollutant was tributyl phosphate with a concentration of 0-100 mg / L.

[0021] Furthermore, the light source has a wavelength of 200-800 nm and a light intensity of 0-200 mW / cm 2 , and perform mechanical disturbance treatment, for example, stirring at a speed of less than 1000 r / min.

[0022] The present invention has the following beneficial effects:

[0023] The present invention provides a preparation method and application of an ultra-efficient nitrate-based free radical activation catalyst, by innovatively preparing bismuth oxybromide (Bi x OBr) nanomaterials successfully solve the technical bottlenecks of low catalytic efficiency and slow reaction rate in traditional photocatalytic technology when treating organic phosphorus pollutants. The main advantages of this invention are: x OBr nanosheet catalysts achieve a dual piezoelectric-photocatalytic effect under conditions of light irradiation and mechanical stirring. The piezoelectric effect induced by photodeformation synergistically activates nitrates in water, efficiently generating hydroxyl radicals and reactive nitrogen species. This allows for efficient degradation of organic pollutants under mild conditions without the need for an external electric field or oxidant. The catalysts prepared in this invention feature readily available, inexpensive raw materials, a simple synthesis process, excellent chemical stability, and recyclability. They achieve a degradation efficiency of over 99.9% for tributyl phosphate (TnBP), a typical organophosphorus flame retardant. This not only enables additive-free, harmless wastewater treatment, avoiding secondary pollution, but also allows for the resourceful utilization of inorganic nitrogen and organic matter. This provides a new, green, efficient, and economically viable solution for the advanced treatment of industrial wastewater, with significant environmental benefits and promising applications.

[0024] Other beneficial effects of the embodiments of the present invention will be further described below. DETAILED DESCRIPTION

[0025] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope of the present invention and its application.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0027] The present invention aims to solve the problem of weak piezoelectric effect in existing piezoelectric photocatalysis and provide a Bi-ion battery that can simultaneously utilize photoelectric and piezoelectric effects. x The preparation method of OBr nanocatalyst and its application in degrading organic pollutants. The photoinduced deformation of the catalyst can enhance its piezoelectric effect, which is beneficial to enhance the generation of free radicals from piezoelectrically activated nitrates.

[0028] The present invention provides a method for preparing an ultra-efficient nitrate free radical activation catalyst, comprising the following steps:

[0029] Step S1: dissolving bismuth nitrate Bi(NO3)3·5H2O and polyvinylpyrrolidone PVP in mannitol solution;

[0030] Step S2: adding potassium bromide (KBr) to the solution of step S1 and performing ultrasonic treatment to form a white suspension;

[0031] Step S3: transferring the suspension to a high-pressure reactor for hydrothermal reaction;

[0032] Step S4: After the reaction is completed, cool the mixture, collect the precipitate by centrifugation, wash it, and freeze-dry it in a vacuum to obtain bismuth oxybromide Bi x OBr nanosheet catalyst. It is understood that the specific value of x in the present invention is not limited as long as the photodeformation-induced piezoelectric effect of the catalyst is satisfied, and preferably x=1 or 2.

[0033] Specific embodiments of the present invention are further described below.

[0034] In some embodiments, bismuth oxybromide (Bi x OBr) nanocatalyst is obtained by combining metal elements and inorganic elements, and its preparation method includes the following steps:

[0035] Step S1: 0-50 mg Bi(NO3)3·5H2O and 0-5 g PVP (molecular weight 10000) were dissolved in 60 mL 0-0.2 M mannitol solution in sequence and magnetically stirred for 0-60 min.

[0036] Step S2: 0-1000 mg KBr was added to the above solution and sonicated for 0-60 min.

[0037] Step S3: Transfer the resulting white suspension into a 100 mL polytetrafluoroethylene (PTFE) autoclave and perform hydrothermal treatment at 0-200 °C for 0-3 h.

[0038] Step S4: After cooling to room temperature, the white precipitate was collected by centrifugation and washed with water and ethanol several times. Finally, Bi was obtained by vacuum freeze drying for 0-50h. x OBr nanosheets.

[0039] The specific operation method of step S4 ethanol washing is to add ethanol to the solution, then put it into a centrifuge for centrifugal separation, and remove the supernatant.

[0040] In some embodiments, a bismuth oxybromide (Bi x OBr) nanocatalyst, weigh 10-100 mg of Bi x The OBr nanocatalyst was placed in a container and added to a 200mL mixed solution of tributyl phosphate (0-100 mg / L) and potassium nitrate (0-50 mg / L). The mixture was then placed under a light source for irradiation and stirring to test its performance. Nitrates were activated through photoelectric and piezoelectric effects to generate free radicals, which effectively removed organic pollutants using the active free radicals. The light source had a wavelength of 200-800nm ​​and an intensity of 0-200 mW / cm 2 , stirring speed is 0-1000 r / min.

[0041] In some embodiments, the Bi x OBr nanocatalyst has photoinduced deformation and piezoelectric effect, and the preparation method includes the following steps:

[0042] 10 mg Bi(NO3)3·5H2O and 1 g PVP (molecular weight 10000) were dissolved in 60 mL 0.075 M mannitol solution in sequence and magnetically stirred for 30 min.

[0043] 500 mg of KBr was added to the above solution and sonicated for 30 min.

[0044] The resulting white suspension was transferred to a 100 mL polytetrafluoroethylene (PTFE) autoclave and subjected to hydrothermal treatment at 160 °C for 2 h.

[0045] After cooling to room temperature, the white precipitate was collected by centrifugation, washed several times with water and ethanol, and finally freeze-dried in a vacuum for 48 hours to obtain BiOBr nanosheets with photodeformation and piezoelectric effects.

[0046] 20 mg Bi(NO3)3·5H2O and 1 g PVP (molecular weight 10000) were dissolved in 60 mL 0.075 M mannitol solution in sequence and magnetically stirred for 30 min.

[0047] 500 mg of KBr was added to the above solution and sonicated for 30 min.

[0048] The resulting white suspension was transferred to a 100 mL polytetrafluoroethylene (PTFE) autoclave and subjected to hydrothermal treatment at 160 °C for 2 h.

[0049] After cooling to room temperature, the white precipitate was collected by centrifugation, washed several times with water and ethanol, and finally freeze-dried in a vacuum for 48 hours to obtain Bi2OBr nanosheets with photodeformation and piezoelectric effects.

[0050] 40 mg Bi(NO3)3·5H2O and 1 g PVP (molecular weight 10000) were dissolved in 60 mL 0.075 M mannitol solution in sequence and magnetically stirred for 30 min.

[0051] 500 mg of KBr was added to the above solution and sonicated for 30 min.

[0052] The resulting white suspension was transferred to a 100 mL polytetrafluoroethylene (PTFE) autoclave and subjected to hydrothermal treatment at 160 °C for 2 h.

[0053] After cooling to room temperature, the white precipitate was collected by centrifugation, washed several times with water and ethanol, and finally freeze-dried in a vacuum for 48 hours to obtain BiOBr nanosheets with photoelectric and piezoelectric effects.

[0054] A Bi-ion battery utilizing photoelectric and piezoelectric effects x Application of OBr catalyst in activating nitrate to produce free radicals for degradation of organic pollutants.

[0055] A photoinduced deformation and piezoelectric effect Bi x The application of OBr catalyst to activate nitrate to produce free radicals to degrade organic pollutants, weigh 10-50 mg of Bi x The OBr nanocatalyst was placed in a container and added to a 200 mL mixed solution of tributyl phosphate (0-100 mg / L) and potassium nitrate (0-100 mg / L). The mixture was placed under a light source and stirred at a stirring speed of 0-1000 r / min.

[0056] Bi prepared by the present invention xThe application of OBr nanocatalyst and its activated nitrate to degrade organic pollutants has the following advantages: good chemical stability, designability and recyclability, etc., and also has the advantages of cheap and readily available raw materials, green and environmentally friendly, simple synthesis process. And the degradation process does not require the introduction of other oxidants to generate free radicals to degrade organic pollutants. x OBr materials can achieve a dual piezoelectric-photocatalytic effect under light irradiation and stirring, achieving a pollutant degradation efficiency exceeding 99.9%. They require no external electric field or oxidant, offer mild reaction conditions, and exhibit stable catalytic activity. This invention is particularly suitable for the advanced treatment and resource utilization of industrial wastewater containing both nitrates and organic pollutants.

[0057] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0058] In the following examples, the Bi x The OBr catalyst was prepared as follows: 3 mg of Bi(NO₃)₃·5H₂O and 0.8 g of PVP (molecular weight 10,000) were dissolved in 50 mL of 0.075 M mannitol solution and magnetically stirred for 10 minutes. 500 mg of KBr was added to the solution and sonicated for 30 minutes. The resulting white suspension was transferred to a 100 mL polytetrafluoroethylene (PTFE) autoclave and hydrothermally treated at 160°C for 1 hour. After cooling to room temperature, the white precipitate was collected by centrifugation and washed several times with water and ethanol. Finally, Bi was obtained by freeze-drying under vacuum for 48 hours. x OBr nanosheets.

[0059] Experimental Example 1

[0060] Weigh 20 mg Bi x The OBr nanocatalyst was placed in a 200 mL mixed aqueous solution containing 10 mg / L of the organic phosphorus flame retardant tributyl phosphate (TnBP) and 30 mg / L of potassium nitrate (KNO3). The reaction system was irradiated under a light source with a wavelength of 200-800 nm and an intensity of 60 mW / cm 2 The mixture was stirred mechanically at 600 r / min. After the reaction was complete, analysis showed that the removal rate of the organophosphorus flame retardant TnBP reached 90.3%.

[0061] Experimental Example 2

[0062] The same experimental conditions as in Experimental Example 1 were used, except that the initial concentration of the organophosphorus flame retardant tributyl phosphate (TnBP) was increased to 50 mg / L. After the reaction was complete, analysis and determination showed that the removal rate of the organophosphorus flame retardant TnBP reached 95.6%.

[0063] Experimental Example 3

[0064] The same experimental conditions as in Experimental Example 1 were used, except that the initial concentration of the organophosphorus flame retardant tributyl phosphate (TnBP) was increased to 100 mg / L. After the reaction was complete, analysis and determination showed that the removal rate of the organophosphorus flame retardant TnBP reached 99.9%.

[0065] Photoelectrically enhanced photo-piezoelectric Bi prepared by the present invention x The nanostructure of the OBr catalyst has high photoinduced deformation efficiency and good piezoelectric effect. By using the light-piezoelectric photocatalytic process of bismuth oxybromide nanomaterials, nitrates are activated to produce free radicals to degrade organic pollutants. The preparation cost is low, the operating conditions are mild, there is no discharge of three wastes, and it is environmentally friendly. The present invention not only achieves the treatment of sewage without additives, harmlessness, stabilization and resource utilization, solves the problems of low efficiency and easy secondary pollution caused by traditional sludge treatment methods, but also improves the efficiency of sewage treatment. At the same time, inorganic nitrogen and organic matter are separately utilized as resources, which makes up for the shortcomings of the existing technology and brings new solutions to the field of sewage treatment.

[0066] Bi prepared by the present invention x The application of OBr nanocatalysts and their activated nitrates for the degradation of organic pollutants offers advantages such as good chemical stability, designability, and recyclability. Furthermore, the raw materials are readily available and environmentally friendly, and the synthesis process is simple. Furthermore, the degradation process does not require the introduction of other oxidants to generate free radicals to degrade organic pollutants.

[0067] The Bi prepared by the present invention x OBr materials can achieve a dual piezoelectric-photocatalytic effect under light irradiation and stirring, achieving a pollutant degradation efficiency exceeding 99.9%. They require no external electric field or oxidant, offer mild reaction conditions, and exhibit stable catalytic activity. This invention is particularly suitable for the advanced treatment and resource utilization of industrial wastewater containing both nitrates and organic pollutants.

[0068] The above description further details the present invention in conjunction with specific / preferred embodiments, and the specific implementation of the present invention should not be construed as being limited to these descriptions. Persons skilled in the art will appreciate that, without departing from the spirit of the present invention, they may make various substitutions or modifications to the described embodiments, and these substitutions or modifications should be considered to fall within the scope of protection of the present invention. Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "preferred embodiments," "examples," "specific examples," or "some examples" indicates that the specific features, structures, materials, or characteristics described in conjunction with such embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Persons skilled in the art may combine and assemble the different embodiments or examples described in this specification, as well as features of different embodiments or examples, without conflicting opinions. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications may be made herein without departing from the scope of protection of the patent application.

Claims

1. A method for preparing an ultra-efficient nitrate free radical activation catalyst, characterized in that: The following steps are involved: S1: Dissolve bismuth nitrate Bi(NO3)3·5H2O and polyvinylpyrrolidone (PVP) in a mannitol solution according to the following ratio: the amount of bismuth nitrate is 3-50 mg, the amount of PVP (molecular weight 10000) is 0.8-5 g, the concentration of mannitol solution is 0.075-0.2 M, and the volume is 50-100 mL; S2: adding potassium bromide (KBr) to the solution of step S1 and ultrasonically treating the solution to form a white suspension, wherein the amount of potassium bromide used is 500-1000 mg and the ultrasonic treatment time is 30-60 minutes; S3: transferring the suspension to a high-pressure reactor for hydrothermal reaction at a temperature of 160-200° C. for 1-3 hours; S4: After the reaction is completed, cool the mixture, collect the precipitate by centrifugation, wash it, and freeze-dry it in a vacuum to obtain bismuth oxybromide Bi x OBr nanosheet catalyst, x=1 or 2, vacuum freeze drying time is 48-50 hours; the catalyst can utilize its photoinduced deformation-induced piezoelectric effect to activate nitrate to generate free radicals without the need for an external electric field and oxidant, thereby degrading organic pollutants.

2. The preparation method according to claim 1, wherein: In step S1, magnetic stirring is performed for 10-60 minutes.

3. The preparation method according to claim 1, wherein: In step S4, washing is performed with water and ethanol in sequence. The specific method of ethanol washing is: adding ethanol to the precipitate, centrifuging and removing the supernatant.

4. Use of an ultra-efficient nitrate radical activation catalyst prepared by the method according to any one of claims 1 to 3 in the degradation of organic pollutants, characterized in that: The bismuth oxybromide Bi x OBr nanosheet catalysts are added to water containing nitrates and organic pollutants, with x = 1 or 2. By utilizing the piezoelectric effect induced by photodeformation, nitrates are activated to generate free radicals without the need for an external electric field or oxidant, thereby degrading organic pollutants.

5. The use according to claim 4, characterized in that: 10-100mg Bi x The OBr nanosheet catalyst is added to 200 mL of a solution containing nitrate and organic pollutants; the nitrate is potassium nitrate with a concentration of 30-100 mg / L; the organic pollutant is tributyl phosphate with a concentration of 10-100 mg / L.

6. The use according to claim 5, characterized in that: The reaction system was placed under a light source with a wavelength of 200-800 nm and an illumination intensity of 60-200 mW / cm 2 , and mechanical disturbance treatment is performed.