CN112007669A - Catalyst and preparation method and application thereof - Google Patents
Catalyst and preparation method and application thereof Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/06—Halogens; Compounds thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/18—Carbon
- B01J21/185—Carbon nanotubes
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- B01J35/39—
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- B01J35/61—
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
- C02F2101/345—Phenols
Abstract
The invention discloses a catalyst, a preparation method and application thereof, belongs to the field of photocatalysts, and solves the problem of low catalytic efficiency of a single catalyst BiOBr. The catalyst consists of carbon nanotubes and BiOBr, wherein the carbon nanotubes account for 2.0-20.0% of the total mass of the catalyst. The preparation method comprises the following steps: pretreating the carbon nano tube; preparing BiOBr; and (3) preparing a CNT-BiOBr composite catalyst. The catalyst of the invention is applied to the degradation of phenolic pollutants. According to the invention, CNT and a catalyst BiOBr are doped and compounded, so that the reaction rate is increased; secondly, the method has excellent selectivity for determining a reaction path; thirdly, the adsorption capacity is improved, and the use of the catalyst is reduced. The invention adopts a hydrolysis-dispersion method to prepare the CNT-BiOBr composite catalyst, and has simple process equipment and higher yield. The catalyst of the present invention can degrade phenols efficiently.
Description
Technical Field
The invention belongs to the field of photocatalysts, and particularly relates to a catalyst and a preparation method and application thereof.
Background
Phenolic compounds are used as an important chemical basic raw material and applied to various industrial manufacturing. A large amount of phenol-containing wastewater with the concentration of 1000-3000 mg/L can be generated in the industries of coal chemical industry, petrochemical industry, fine chemical industry and the like; in addition, petroleum refineries, wood preservation plants, shale refineries, and various industries that synthesize phenol or use phenol as a raw material, such as synthetic fibers, medicines, dyes, pesticides, disinfectants, paints, and the like, all produce large amounts of phenol-containing wastewater.
The phenol-containing wastewater has wide source, large quantity and strong harmfulness, and the discharge of the phenol-containing wastewater brings serious pollution to the environment, brings harm to the growth and reproduction of organisms and the health of human bodies, and even influences the sustainable development of economy. The phenolic compounds are prototype toxicants, belong to high-toxicity substances, and have toxic action on all biological individuals.
With the understanding of people on the harm of phenolic compounds, the treatment technology of phenolic wastewater is continuously developed. At present, the domestic and foreign treatment methods for the phenol-containing wastewater mainly comprise an adsorption method, an extraction method, an air stripping method, a membrane technology method, a chemical precipitation method, a chemical oxidation method and the like.
(1) Adsorption process
The essence of the adsorption method for treating the phenol-containing wastewater is that an adsorbent with high specific surface area and strong adsorption capacity is used for adsorbing the phenol compounds in the wastewater, and then steam, alkali liquor or an organic solvent is used for desorption. The phenol-containing wastewater treatment method has the advantages of simple equipment, convenient operation and high adsorption speed, is successfully applied to wastewater treatment, has strict requirements on the selection of the adsorbent, is only suitable for treating phenol-containing wastewater with lower concentration, has the treatment effect on the phenol-containing wastewater far reaching the national discharge standard, and also needs secondary treatment. Therefore, the adsorption method is not suitable for treating phenol-containing wastewater alone.
(2) Extraction process
The essence of the extraction method is that an extractant which is difficult to dissolve in water is added into the phenol-containing wastewater, and the phenolic compounds are transferred from a water phase to an extraction solvent phase, so that the phenolic compounds are separated from the wastewater. The method has strict requirements on the extracting agent, and has the characteristics of higher solubility, good chemical stability, convenient source, easy recovery and the like on the phenolic compounds. The solvent extraction method has good effect on the treatment of the phenol-containing wastewater, the equipment is simple, the operation is complex, and the extractant can bring secondary pollution to the environment.
(3) Steam stripping process
The essence of the steam stripping method is that the phenol-containing wastewater is distilled to form an azeotropic mixture of volatile phenol and water vapor, and the phenol is separated from the wastewater by utilizing the concentration difference of the volatile phenol compounds in a gas phase and a water phase, thereby achieving the purpose of purifying water. The method is simple to operate in the process of treating the phenol-containing wastewater, does not cause secondary pollution, and can recover high-purity phenol. However, the method is only suitable for treating wastewater containing volatile and high-concentration phenol, and the removal rate of the phenol is only 70-80 percent generally.
(4) Membrane technology method
The membrane technology method is mainly used for removing phenolic compounds in the wastewater through a reverse osmosis method and an ultrafiltration method. The method has the advantages of high treatment effect on the phenol-containing wastewater, simple equipment and low cost. The removal rate of the waste water of catechol treated by the Korea Weiqing and the like through a liquid membrane method reaches 95-98 percent, and the national discharge standard is reached. However, this method is very complicated in operation and requires a step of producing milk, breaking emulsion, or the like.
(5) Chemical precipitation method
The essence of the chemical precipitation method is that certain chemical reagents are added into the phenol-containing waste water to react with the phenolic compounds in the waste water to generate insoluble precipitate, so that the phenolic compounds are separated from the water. The method has good treatment effect on the high-concentration phenol-containing wastewater, but a large amount of chemical precipitator is required to be added in the treatment process, so that not only is secondary pollution brought to the environment, but also no good treatment method for a large amount of precipitates generated in the treatment process exists.
(6) Chemical oxidation process
The essence of the chemical oxidation method is that some oxidizing agents are added into the phenolic wastewater, and the phenolic compounds in the wastewater are oxidatively degraded into small molecular alkanes, carbon dioxide and water by utilizing the strong oxidizing property of the oxidizing agents. Wherein the photochemical oxidation method is an advanced oxidation treatment technology with higher treatment efficiency in the sewage treatment technology. The essence is that oxidation reaction is carried out under the condition of illumination, and active species generated by photocatalysis attack phenolic pollutants, so that the phenolic pollutants are oxidized and cracked to be converted into micromolecular alkane and CO2、H2And O, finally achieving the aim of mineralization. The photocatalysis technology has the advantages of mild degradation reaction conditions, low energy consumption, thorough destruction of organic matters, no secondary pollution and the like, so the photocatalysis technology has wide application prospect in the aspect of phenolic wastewater treatment. However, the single photocatalyst BiOBr has low catalytic efficiency, small specific surface area, and poor hydrophilicity and adsorption performance.
Disclosure of Invention
The invention aims to provide a catalyst to solve the problem of low BiOBr catalytic efficiency of a single catalyst.
Another object of the present invention is to provide a method for preparing a catalyst.
It is a further object of the present invention to provide a use of the catalyst.
The technical scheme of the invention is as follows: a catalyst consisting of Carbon Nanotubes (CNTs) and BiOBr, wherein the carbon nanotubes comprise between 2.0% and 20.0% of the total mass of the catalyst.
A method of preparing a catalyst comprising the steps of:
A. pretreatment of the carbon nanotubes: putting the carbon nano tube into a container, sequentially adding concentrated sulfuric acid and concentrated nitric acid, stirring and mixing uniformly, heating to 60-90 ℃, keeping the temperature for 20-60min, separating the carbon nano tube from acid liquor after acidification is finished, washing the carbon nano tube to be neutral by using ultrapure water, and drying in an oven at 60-90 ℃ for 1-3h for later use;
B. preparing BiOBr;
C. preparation of CNT-BiOBr composite catalyst: and B, putting the CNT pretreated in the step A into ultrapure water, performing ultrasonic treatment for 10-20min, adding BiOBr in a corresponding ratio into the turbid liquid, continuing performing ultrasonic treatment for 5-20min, heating to 60-90 ℃, stirring at a constant temperature for 1-5h, evaporating the water in the solution, and fully combining the carbon nano tube with the BiOBr to obtain the target catalyst.
As a further improvement of the invention, in the step C, the mass fraction of the carbon nano-tubes in the target catalyst is obtained to be 2-20%.
As a further improvement of the invention, in the step a, the mass fraction of the concentrated sulfuric acid is 98%, and the mass fraction of the concentrated nitric acid is 68%; the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is 3: 1.
As a further improvement of the invention, in the step A, the heating temperature is 80 ℃, the heat preservation time is 30min, the drying temperature is 90 ℃, and the drying time is 1 h.
As a further improvement of the present invention, in step B, the preparation method of the BiOBr is as follows: according to the molar ratio of Bi to Br of 1: 1 Bi (NO) is weighed3)3·5H2O and KBr, reacting Bi (NO)3)3·5H2Putting O into a polytetrafluoroethylene reaction lining filled with ethylene glycol, stirring for 30-60min by a magnetic stirrer, adding KBr, stirring for 30-60min, transferring into a high-temperature reaction kettle, putting into a drying oven, heating for 2-5h at the constant temperature of 80-180 ℃, naturally cooling to room temperature, carrying out suction filtration by a water circulation vacuum pump, collecting a product, alternately washing by deionized water and absolute ethyl alcohol, and drying for 2-5h at the temperature of 80-100 ℃ in the drying oven to obtain an off-white product BiOBr.
As a further improvement of the invention, in the step B, the stirring time is 20min before adding KBr, the stirring time is 40min after adding KBr, the reaction temperature in the oven is 120 ℃, the reaction time is 3h, the drying temperature is 70 ℃, and the drying time is 3 h.
The application of a catalyst in the degradation of phenolic pollutants.
Carbon Nanotubes (CNTs) have a specific surface area and a void structure, and the bonding state and electronic state of the surface are different from those of the inside of the particle. Incomplete atomic coordination on the surface of the carbon nano tube can cause the increase of active sites on the surface, so that the carbon nano tube has certain degradation performance on organic matters, and basic conditions are provided for the carbon nano tube to be used as a catalyst.
BiOBr as a novel narrow-band-gap semiconductor material (the forbidden band width is 2.5-2.9eV) has the advantages of unique electronic structure, good optical performance, good catalytic performance and the like. By utilizing the advantages of better activity and stability of the photocatalyst to various dyes and the like, the photocatalyst which has the advantages of high specific surface area, excellent mesoporous structure, low cost and the like, and high activity and universality under visible light can be prepared by compounding the photocatalyst with Carbon Nano Tubes (CNT).
In order to overcome the defects that a single photocatalyst has low catalytic efficiency, small specific surface area, poor hydrophilicity, poor adsorption performance and the like, the invention takes the Carbon Nano Tube (CNT) with special specific surface area and void structure as a carrier, and loads the photocatalyst BiOBr on the carbon nano tube.
The invention has the beneficial effects that:
1. according to the invention, the CNT and the catalyst BiOBr are compounded according to a certain proportion, so that the specific surface area of the material is greatly increased, and the photocatalysis performance of the BiOBr is effectively improved by virtue of the synergistic effect of the CNT. The CNT is used as a dispersed template to control the form of the BiOBr nano particles and improve the specific surface area of the material; due to the fact that the CNT has good electron conductivity, recombination of electron-hole pairs can be effectively hindered between the BiOBr nano particles and the CNT, and due to the two reasons, the photocatalytic activity of the CNT-BiOBr composite material is improved. Doping and compounding CNT and a catalyst BiOBr according to a certain proportion, wherein the reaction rate is increased; secondly, the method has excellent selectivity for determining a reaction path; thirdly, the adsorption capacity is improved, and the use of the catalyst is reduced.
2. The invention adopts a hydrolysis-dispersion method to prepare the CNT-BiOBr composite catalyst, and has the advantages of simple process equipment, convenient operation, strong parameter controllability of each step and higher yield.
3. The catalyst disclosed by the invention can be used for quickly realizing the separation of photoproduction electrons and holes under the irradiation of visible light and efficiently degrading phenols, and the degradation rate is higher than 90% in 30min under the irradiation of the visible light.
Drawings
Fig. 1 is a graph showing the degradation effect of doped CNT-BiOBr composite catalysts with different CNT contents on hydroquinone solution in comparative example 1 and example 1.
Detailed Description
The present invention will be described in detail with reference to specific embodiments.
And (I) selecting CNT pretreatment parameters with optimal performance through experiments.
CNTs were pretreated as follows: weighing a certain amount of CNT, placing the CNT into a 250mL round-bottom flask, sequentially adding 30mL of 98 wt% concentrated sulfuric acid and 10mL of 68 wt% concentrated nitric acid, slowly stirring and uniformly mixing, heating to a certain temperature (tests respectively consider 60, 80 and 90 ℃), keeping the temperature for a period of time (tests respectively consider 20, 30 and 60min), separating the CNT from an acid solution after acidification is finished, washing the CNT to be neutral by using ultrapure water, and placing the CNT into an oven for drying (tests respectively consider 1, 2 and 3h) at a certain temperature (tests respectively consider 60, 70 and 90 ℃) for later use.
Under the above experimental conditions, a CNT with the best performance is selected and used as a precursor for the subsequent synthesis of the composite material. The statistics of the orthogonal experiments for CNT pretreatment are shown in table 1.
TABLE 1
Considering energy consumption, time and the like comprehensively, the optimal pretreatment reaction conditions of the CNT are preferably as follows: the reaction temperature is 80 ℃, the reaction time is 30min, the drying temperature is 90 ℃, the drying time is 1h, and the CNT obtained under the conditions has no agglomeration, smooth surface and no impurities.
And (II) selecting BiOBr preparation parameters with optimal performance through tests.
The BiOBr was prepared as follows: according to the molar ratio of Bi to Br of 1: 1 Bi (NO) is weighed3)3·5H2O and KBr, reacting Bi (NO)3)3·5H2Placing O into a polytetrafluoroethylene reaction liner containing ethylene glycol, stirring for a certain time by a magnetic stirrer (30, 40 and 60min are respectively considered in the tests), adding KBr, stirring again (30, 40 and 60min are respectively considered in the tests), then moving into a high-temperature reaction kettle, placing into an oven, heating at a constant temperature of 80, 100, 120, 150 and 180 ℃ in the tests (2, 3, 4 and 5h are respectively considered in the tests), naturally cooling to room temperature, performing suction filtration by a water circulation vacuum pump, collecting a product, alternately washing with deionized water and absolute ethyl alcohol for three times, and drying in the oven (80, 90 and 100 ℃ in the tests (2, 3 and 5h are respectively considered in the tests) to obtain an off-white product BiOBr.
Under the above experimental conditions, a BiOBr with the best performance is selected and used as a precursor for the subsequent synthesis of the composite material. The statistics of the results of the orthogonal experiments for the preparation of bismuth oxybromide are shown in table 2.
TABLE 2
Considering the factors of energy consumption, dissolving time, mixing time, reaction time, drying time and the like comprehensively, the optimal preparation reaction conditions of the bismuth oxybromide are preferably as follows: the bismuth bromide oxide prepared under the conditions has the highest photocatalytic performance, wherein the bismuth nitrate is dissolved for 20min, the bismuth nitrate and potassium bromide are mixed for 40min, the reaction temperature is 120 ℃, the reaction time is 3h, the drying temperature is 70 ℃, and the drying time is 3 h.
Comparative examples 1,
The simple BiOBr catalyst, i.e. with a CNT content of 0, is labeled as 0.0 wt% CNT-BiOBr catalyst. And preparing the BiOBr according to the optimal parameters to obtain the 0.0 wt% CNT-BiOBr catalyst.
Degradation experiments: 0.2g of 0.0 wt% CNT-BiOBr catalyst was dispersed in 50mL of 100mg/L Hydroquinone (HQ), the reaction system was placed in a photochemical reactor and stirred in the dark for adsorption, and after absorption and desorption equilibrium was reached, the reaction system was irradiated with a 300W mercury lamp and started to time, samples were taken every 10min, the absorbance of the supernatant was measured at λ 288nm and the degradation rate was 87.15% by illumination for 30 min.
Examples 1,
The catalyst comprises the following components in percentage by mass:
A. pretreatment of the carbon nanotubes: pretreating CNTs according to the optimal parameters;
B. preparation of BiOBr: as in comparative example 1.
C. Preparation of CNT-BiOBr composite catalyst: b, putting the CNT pretreated in the step A which is accurately weighed into ultrapure water, carrying out ultrasonic treatment for 10-20min, adding the BiOBr prepared in the step two with the corresponding proportion into the turbid liquid, and carrying out continuous ultrasonic treatment for 5-20 min; heating to 60-90 ℃, stirring at constant temperature for 1-5h to evaporate water in the solution, and fully combining the CNT and the BiOBr to obtain the composite catalyst with different CNT doping amounts of 2 wt%, 5 wt%, 8 wt%, 12 wt% and 20 wt%.
Degradation experiments of CNT-BiOBr composite catalysts were examined in single factor with doping amounts of CNTs (2 wt%, 5 wt%, 8 wt%, 12 wt%, 20 wt%) under otherwise unchanged conditions: respectively dispersing 0.2g of 2 wt%, 5 wt%, 8 wt%, 12 wt% and 20 wt% of CNT-BiOBr composite catalyst into 50mL of HQ solution of 100mg/L, placing the reaction system in a photochemical reactor, stirring in the dark for adsorption, stirring in the dark for 30min to reach adsorption and desorption equilibrium, irradiating by using a 300W mercury lamp, starting timing, taking samples every 10min, and measuring the absorbance of the supernatant at the position of lambda-288 nm.
And (3) converting the absorbance into concentration according to Lambert-beer law, calculating the concentration change of HQ before and after illumination and the degradation rate of the HQ (see the following formula), and evaluating the photocatalytic activity of the CNT-BiOBr.
In the formula: eta is HQ degradation rate, C0The concentration of HQ solution before irradiation with light, CtThe HQ solution concentration after light irradiation.
The degradation rates are 89.71%, 95.19%, 97.82%, 96.10% and 95.00% respectively after illumination for 30 min.
The degradation effect of the doped CNT-BiOBr composite catalyst on the HQ solution at different CNT contents (0.0 wt%, 2 wt%, 5 wt%, 8 wt%, 12 wt%, 20 wt%) in comparative example 1 and example 1 is shown in fig. 1, from which it can be seen that the degradation effect is the best when the mass fraction of CNTs in the CNT-BiOBr composite catalyst is 8%.
The following examples examine the effect of other experimental conditions on the performance of the preferred 8 wt% CNT-BiOBr composite catalyst.
Examples 2,
Step A and step B are the same as in example 1;
and step C, accurately weighing 0.08g of the preferred CNT according to 8 wt% of the CNT doped in the composite catalyst, putting the CNT into 50mL of ultrapure water, performing ultrasonic treatment for 15min, adding the BiOBr which is preferably selected in a corresponding proportion into the turbid solution, performing continuous ultrasonic treatment for 10min, heating to 60 ℃, stirring for 5h at constant temperature, evaporating the water of the solution, and fully combining the CNT and the BiOBr to obtain the 8 wt% CNT-BiOBr composite catalyst.
Degradation experiments: dispersing 0.2g of CNT-BiOBr composite catalyst into 50mL of 100mg/L HQ solution, placing the reaction system in a photochemical reactor, stirring in the dark for adsorption, stirring in the dark for 30min to reach adsorption and desorption equilibrium, irradiating by using a 300W mercury lamp, starting timing, taking samples every 10min, and measuring the absorbance of the supernatant at the position of which lambda is 288 nm. The degradation rate is 98.12 percent after illumination for 30 min.
Examples 3,
Step A and step B are the same as in example 1;
and step C, accurately weighing 0.08g of the preferred CNT according to 8 wt% of the CNT doped in the composite catalyst, putting the CNT into 50mL of ultrapure water, performing ultrasonic treatment for 20min, adding the BiOBr which is preferably selected in a corresponding proportion into the turbid solution, performing continuous ultrasonic treatment for 20min, heating to 90 ℃, stirring for 1h at constant temperature, evaporating the water of the solution, and fully combining the CNT and the BiOBr to obtain the 8 wt% CNT-BiOBr composite catalyst.
Degradation experiments: dispersing 0.2g of CNT-BiOBr composite catalyst into 50mL of 100mg/L HQ solution, placing the reaction system in a photochemical reactor, stirring in the dark for adsorption, stirring in the dark for 30min to reach adsorption and desorption equilibrium, irradiating by using a 300W mercury lamp, starting timing, taking samples every 10min, and measuring the absorbance of the supernatant at the position of which lambda is 288 nm. The degradation rate is 98.54 percent after illumination for 30 min.
Examples 4,
Step A and step B are the same as in example 1;
and step C, accurately weighing 0.08g of the preferred CNT according to 8 wt% of the CNT doped in the composite catalyst, putting the CNT into 50mL of ultrapure water, performing ultrasonic treatment for 10min, adding the BiOBr which is preferably selected in a corresponding proportion into the turbid solution, performing continuous ultrasonic treatment for 15min, heating to 80 ℃, stirring for 2h at constant temperature, evaporating the water of the solution, and fully combining the CNT and the BiOBr to obtain the 8 wt% CNT-BiOBr composite catalyst.
Degradation experiments: dispersing 0.2g of CNT-BiOBr composite catalyst into 50mL of 100mg/L HQ solution, placing the reaction system in a photochemical reactor, stirring in the dark for adsorption, stirring in the dark for 30min to reach adsorption and desorption equilibrium, irradiating by using a 300W mercury lamp, starting timing, taking samples every 10min, and measuring the absorbance of the supernatant at the position of which lambda is 288 nm. The light irradiation is carried out for 30min, and the degradation rate is 99.36 percent.
As can be seen from examples 2-4, the 8 wt% CNT-BiOBr composite catalyst shows excellent photocatalytic performance under the corresponding synthesis conditions in examples 2-4, after the CNT is subjected to ultrasonic treatment for 10min, the BiOBr which is preferably selected according to the corresponding proportion is added into the CNT turbid liquid, the CNT turbid liquid is subjected to continuous ultrasonic treatment for 15min, the 8 wt% CNT-BiOBr composite catalyst which is synthesized under the conditions of heating to 80 ℃ and stirring for 2h at constant temperature has the best performance, the illumination is 30min, and the degradation rate of HQ is as high as 99.36%.
Claims (8)
1. A catalyst, characterized by: the catalyst consists of carbon nanotubes and BiOBr, wherein the carbon nanotubes account for 2.0-20.0% of the total mass of the catalyst.
2. A method for preparing the catalyst of claim 1, comprising the steps of:
A. pretreatment of the carbon nanotubes: putting the carbon nano tube into a container, sequentially adding concentrated sulfuric acid and concentrated nitric acid, stirring and mixing uniformly, heating to 60-90 ℃, keeping the temperature for 20-60min, separating the carbon nano tube from acid liquor after acidification is finished, washing the carbon nano tube to be neutral by using ultrapure water, and drying in an oven at 60-90 ℃ for 1-3h for later use;
B. preparing BiOBr;
C. preparation of CNT-BiOBr composite catalyst: and B, putting the CNT pretreated in the step A into ultrapure water, performing ultrasonic treatment for 10-20min, adding BiOBr in a corresponding ratio into the turbid liquid, continuing performing ultrasonic treatment for 5-20min, heating to 60-90 ℃, stirring at a constant temperature for 1-5h, evaporating the water in the solution, and fully combining the carbon nano tube with the BiOBr to obtain the target catalyst.
3. A method of preparing a catalyst according to claim 2, wherein: in the step C, the mass fraction of the carbon nano-tubes in the obtained target catalyst is 2-20%.
4. A method of preparing a catalyst as claimed in claim 2 or 3, wherein: in the step A, the mass fraction of the concentrated sulfuric acid is 98 percent, and the mass fraction of the concentrated nitric acid is 68 percent; the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is 3: 1.
5. The method of claim 4, wherein: in the step A, the heating temperature is 80 ℃, the heat preservation time is 30min, the drying temperature is 90 ℃, and the drying time is 1 h.
6. A catalyst preparation according to claim 2The method is characterized in that: in step B, the preparation of BiOBr is as follows: according to the molar ratio of Bi to Br of 1: 1 Bi (NO) is weighed3)3·5H2O and KBr, reacting Bi (NO)3)3·5H2Putting O into a polytetrafluoroethylene reaction lining filled with ethylene glycol, stirring for 20-60min by a magnetic stirrer, adding KBr, stirring for 30-60min, transferring into a high-temperature reaction kettle, putting into a drying oven, heating for 2-5h at the constant temperature of 80-180 ℃, naturally cooling to room temperature, carrying out suction filtration by a water circulation vacuum pump, collecting a product, alternately washing by deionized water and absolute ethyl alcohol, and drying for 2-5h in the drying oven at the temperature of 70-100 ℃ to obtain an off-white product BiOBr.
7. The method of claim 6, wherein: in the step B, the stirring time is 20min before adding KBr, the stirring time is 40min after adding KBr, the reaction temperature in the oven is 120 ℃, the reaction time is 3h, the drying temperature is 70 ℃, and the drying time is 3 h.
8. Use of the catalyst of claim 1 for the degradation of phenolic contaminants.
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