Oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst and its preparation method and application

Abstract

The present invention provides a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles, a preparation method, and an application thereof. The composite photocatalyst comprises oxygen-deficient bismuth phosphate nanorods and cobalt nanoparticles loaded on the surfaces of the oxygen-deficient bismuth phosphate nanorods; the cobalt nanoparticle loading amount is 5-30wt% based on the total weight of the oxygen-deficient bismuth phosphate nanorods as 100%. The composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles is used for the synergistic degradation of antibiotics through photocatalysis and persulfate advanced oxidation technology. The composite photocatalyst exhibits high degradation activity, a significantly reduced band gap width, a red-shifted spectral response, and a significantly increased degradation rate compared to pure bismuth phosphate.

Description

Technical Field

[0001] The invention relates to an oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst and a preparation method and application thereof, belonging to the field of material technology, particularly the field of catalytic material technology. Background Art

[0002] Since the discovery of the first antibiotic, penicillin, scientists have synthesized nearly 10,000 antibiotics, which have played an important role in the prevention and treatment of human and animal diseases. However, the pollution caused by the excessive use of antibiotics to the water environment has become a global environmental problem. As an environmentally friendly and non-secondary pollution technology, persulfate advanced oxidation technology produces SO4 with a high oxidation potential. - , can treat organic wastewater green and efficiently. Cobalt has been proven to be the best persulfate activator, forming Co 2+ →Co 3+ →Co 2+ The redox cycle of Co 3+ →Co 2+ It is the rate-controlling step in this cycle. 2+ Regeneration rate is currently a research hotspot in this field.

[0003] Photocatalytic technology is an environmental purification technology that has developed rapidly in recent decades. It can mineralize organic pollutants into carbon dioxide and water without secondary pollution, and has unique advantages in degrading highly toxic, low-concentration organic pollutants in wastewater environments. Monoclinic monazite phase bismuth phosphate (BiPO4) has attracted much attention due to its highly stable chemical structure, non-toxicity, and excellent photocatalytic properties. It is reported that the specific surface area of ​​BiPO4 is only about 1 / 16 of that of commercial P25, and its surface area specific activity is more than 30 times that of P25, making it a hot topic in the current photocatalytic research field. However, BiPO4 has disadvantages such as a high recombination rate of photogenerated electron-hole pairs and a narrow light absorption range.

[0004] Therefore, providing a low-cost, environmentally friendly and highly active catalytic material and a preparation method thereof is a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0005] In order to solve the above-mentioned shortcomings and deficiencies, an object of the present invention is to provide a composite photocatalyst of bismuth phosphate nanorods loaded with cobalt nanoparticles rich in oxygen defects.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst.

[0007] Another object of the present invention is to provide the use of the above-mentioned oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst in the degradation of antibiotics under the synergistic action of photocatalysis and persulfate advanced oxidation technology.

[0008] Another object of the present invention is to provide a method for degrading antibiotics through the synergistic action of photocatalysis and persulfate advanced oxidation technology, which uses the above-mentioned oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst.

[0009] In order to achieve the above objectives, on the one hand, the present invention provides a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles, wherein the composite photocatalyst comprises oxygen-deficient bismuth phosphate nanorods and cobalt nanoparticles loaded on the surface of the oxygen-deficient bismuth phosphate nanorods;

[0010] Based on the total weight of the oxygen defect-rich bismuth phosphate nanorods being 100%, the loading amount of the cobalt nanoparticles is 5-30 wt%.

[0011] As a specific embodiment of the composite photocatalyst described above, the length of the oxygen-deficient bismuth phosphate nanorods is about 300-400 nm, and the width is about 100-200 nm.

[0012] As a specific embodiment of the composite photocatalyst described above in the present invention, the size of the cobalt nanoparticles is 30-50 nm.

[0013] On the other hand, the present invention also provides a method for preparing the above-mentioned oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst, wherein the preparation method comprises:

[0014] Step 1: Add bismuth salt and phosphate into water, mix well and then conduct hydrothermal reaction to obtain BiPO4;

[0015] Step 2: calcining BiPO4 at high temperature in a hydrogen-nitrogen mixed gas or hydrogen-argon mixed gas atmosphere to obtain bismuth phosphate rich in oxygen defects, namely BiPO 4-x , which is a light grey powder; wherein, BiPO 4-x The "4-x" in the formula indicates that there is a missing oxygen atom in the bismuth phosphate;

[0016] Step 3: BiPO 4-x The bismuth phosphate nanorods rich in oxygen defects and the cobalt source are dissolved in water, mixed evenly and then evaporated in a water bath to obtain the cobalt nanoparticle-loaded composite photocatalyst.

[0017] As a specific embodiment of the preparation method described above of the present invention, wherein the bismuth salt includes bismuth nitrate and / or bismuth chloride;

[0018] The phosphate includes one or a combination of sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium phosphate, etc.

[0019] The present invention does not impose specific requirements on the amounts of bismuth salt, phosphate, and water used in step 1 of the preparation method described above. These amounts can be adjusted according to actual operating conditions, as long as the purpose of producing BiPO4 is achieved. In some embodiments of the present invention, the amount of bismuth salt used can be 0.75-3 mmol, the amount of phosphate used can be 2.7-10.8 mmol, and the amount of solvent water used can be 50-80 mL.

[0020] As a specific embodiment of the above-mentioned preparation method of the present invention, in step 1, the temperature of the hydrothermal reaction is 120-200° C., and the time is 12-36 hours. The hydrothermal reaction can be carried out in a conventional reactor.

[0021] As a specific embodiment of the preparation method described above, in step 1, the mixing is achieved by constant temperature stirring at a temperature of 10-50° C. for 1-10 hours. In some embodiments of the present invention, the stirring can be, for example, magnetic stirring to fully dissolve the bismuth salt and the phosphate in water.

[0022] As a specific embodiment of the preparation method described above, in step 2, the volume ratio of hydrogen in the hydrogen-nitrogen mixed gas or hydrogen-argon mixed gas atmosphere is 5-20%, and the flow rate of the hydrogen-nitrogen mixed gas or hydrogen-argon mixed gas is 30-100 mL min -1 .

[0023] As a specific embodiment of the above preparation method of the present invention, the high-temperature calcination includes heating the temperature to 200-350° C. at a heating rate of 1-5° C. / min and calcining for 1-4 hours.

[0024] As a specific embodiment of the above-mentioned preparation method of the present invention, the uniform mixing in step 3 can be achieved by ultrasonic treatment.

[0025] As a specific embodiment of the preparation method described above, in step 3, the water bath evaporation temperature is 40-100° C., preferably 80° C., and the time is 4-10 h. In some embodiments of the present invention, the water bath evaporation is performed under stirring conditions.

[0026] As a specific embodiment of the above preparation method of the present invention, the cobalt source includes cobalt nitrate and / or cobalt chloride, etc., preferably cobalt nitrate.

[0027] As a specific embodiment of the preparation method described above, step three further includes vacuum drying the mixture obtained by water bath evaporation to obtain the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst. The present invention does not impose specific requirements on the temperature and time of vacuum drying, which can be reasonably adjusted according to actual on-site operational needs, as long as the drying objective is achieved. In some embodiments of the present invention, the vacuum drying temperature can be, for example, 80°C.

[0028] In another aspect, the present invention also provides the use of the above-mentioned oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst in the degradation of antibiotics under the synergistic action of photocatalysis and persulfate advanced oxidation technology.

[0029] As a specific embodiment of the above application of the present invention, the antibiotics include tetracycline hydrochloride and the like.

[0030] In another aspect, the present invention further provides a method for degrading antibiotics by synergistic action of photocatalysis and persulfate advanced oxidation technology, wherein the method comprises the following steps:

[0031] The above-mentioned oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst is added to the target pollutant containing antibiotics. After adsorption equilibrium in the dark, persulfate is added and the light source is turned on to react. After the reaction is completed, the degradation of the antibiotics is completed.

[0032] As a specific implementation of the above method of the present invention, the light source is an LED lamp.

[0033] As a specific embodiment of the method described above, the power of the LED lamp is 100-500 mW, preferably 200 mW, the wavelength is 254 nm, and the intensity is 50-150 mW / cm 2 , preferably 100mW / cm 2 The light source is 3-25 cm away from the reaction liquid surface, preferably 5 cm.

[0034] As a specific embodiment of the above method of the present invention, the reaction temperature is 10-80°C, preferably 20°C.

[0035] As a specific embodiment of the above-described method of the present invention, the mass ratio of the oxygen-deficient bismuth phosphate nanorod-supported cobalt nanoparticle composite photocatalyst, the antibiotic, and the persulfate is 8:1:6-8:1:12. In some embodiments of the present invention, the amounts of the oxygen-deficient bismuth phosphate nanorod-supported cobalt nanoparticle composite photocatalyst, the antibiotic, and the persulfate are 10-50 mg, 0.5-2.5 mg, and 3-30 mg, respectively.

[0036] As a specific embodiment of the above method of the present invention, the antibiotics include tetracycline hydrochloride and the like.

[0037] The present invention does not make any specific requirements on the specific material of the persulfate, and can be reasonably selected according to the actual situation on site, as long as it can achieve the purpose of the present invention. For example, in some embodiments of the present invention, the persulfate can be potassium monopersulfate purchased from San Chemical Technology Co., Ltd., and its molecular formula is H3K5O 18 S4.

[0038] This invention synergizes photocatalysis and persulfate advanced oxidation technology. The photoactivated persulfate and photocatalyst generate electrons upon photoexcitation, accelerating electron cycle efficiency and reducing the recombination of photogenerated electrons and holes, thereby enhancing antibiotic degradation activity. Furthermore, the inclusion of cobalt increases the oxygen vacancy concentration, reduces the band gap, and improves light energy utilization.

[0039] Compared with the prior art, the present invention can achieve the following beneficial technical effects:

[0040] (1) The active component of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided by the present invention is cobalt nanoparticles, and the size of the cobalt nanoparticles is 30-50 nm. When the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst is used for the synergistic degradation of antibiotics such as tetracycline hydrochloride by photocatalysis and persulfate advanced oxidation technology, the presence of cobalt can efficiently activate persulfate to form Co 2+ →Co 3+ →Co 2+ In addition, the loading of Co(Ⅱ) nanoparticles increases the oxygen defect concentration of the catalytic material, that is, the composite photocatalyst, which can capture more electrons to participate in the cycle process and mediate the Co 3+ Extracting electrons from antibiotic molecules such as tetracycline hydrochloride for Co 2+ →Co 3+ →Co 2+ The cyclic process continuously activates persulfate, utilizing the pollutant itself to accelerate its degradation. Simultaneously, the electrons generated by the photoexcitation of the oxygen-deficient bismuth phosphate nanorods can also be used in the aforementioned cyclic process, effectively suppressing the recombination of electron-hole pairs and thus enhancing the composite photocatalytic activity.

[0041] (2) The carrier in the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided by the present invention is an oxygen-deficient bismuth phosphate nanorod, which has a length of about 300-400nm and a width of about 100-200nm. The oxygen-deficient bismuth phosphate nanorod has a one-dimensional structure of a nanorod (that is, the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst has a one-dimensional structure of a nanorod), so that the transmission of electrons therein is one-dimensional. Its one-dimensional structure shortens the path for photogenerated electrons and holes to migrate to the surface of the photocatalyst, promotes the separation of photogenerated carriers, and improves the carrier utilization rate; at the same time, there are oxygen defects in the oxygen-deficient bismuth phosphate nanorod, which can quickly capture and release electrons, separate electrons and holes in space, and make the photocatalytic degradation have a better effect.

[0042] (3) The participation of cobalt in the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared by the present invention can broaden the light absorption range and reduce the band gap width, and the energy required to excite electrons to migrate from the valence band to the conduction band is reduced, which theoretically proves that it has higher chemical reaction activity and is conducive to the progress of photocatalytic reactions.

[0043] (4) The preparation method of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided by the present invention is simple and environmentally friendly.

[0044] (5) The oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst is used for the synergistic degradation of antibiotics, such as tetracycline hydrochloride, by photocatalysis and persulfate advanced oxidation technology. The composite photocatalyst has high degradation activity. Compared with pure bismuth phosphate, the band gap width is significantly reduced, the spectral response is red-shifted, and the degradation rate is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 This is a SEM image of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1 of the present invention.

[0047] Figure 2 This is a TEM image of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1 of the present invention.

[0048] Figure 3 This is the SEM image of the bismuth phosphate photocatalyst prepared in Comparative Example 1.

[0049] Figure 4 This is the SEM image of the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2.

[0050] Figure 5 This is a comparison diagram of the N2 adsorption-desorption isotherms of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1 of the present invention, the bismuth phosphate photocatalyst prepared in Comparative Example 1, and the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2.

[0051] Figure 6 This is a comparison chart of the ultraviolet-visible diffuse reflectance spectra of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1 of the present invention, the bismuth phosphate photocatalyst prepared in Comparative Example 1, and the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2.

[0052] Figure 7 This is a comparison chart of the band gap spectra of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1 of the present invention, the bismuth phosphate photocatalyst prepared in Comparative Example 1, and the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2.

[0053] Figure 8 This is a comparison chart of the O1s spectra of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1 of the present invention, the bismuth phosphate photocatalyst prepared in Comparative Example 1, and the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2.

[0054] Figure 9 This is a graph showing the relationship between the removal rate and time of tetracycline hydrochloride synergistically degraded by the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst and persulfate advanced oxidation technology provided in Examples 1 to 4 in Application Example 1 of the present invention.

[0055] Figure 10 This is a schematic diagram comparing the removal rate and time relationship curves of the synergistic degradation of tetracycline hydrochloride by the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1 of the present invention and the bismuth phosphate photocatalyst prepared in Comparative Example 1, respectively, with the persulfate advanced oxidation technology.

[0056] Figure 11 This is a schematic diagram comparing the removal rate and time relationship curves of the synergistic degradation of tetracycline hydrochloride by photocatalysis and persulfate advanced oxidation technology using the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1 of the present invention, and the photocatalytic degradation of tetracycline hydrochloride by the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1. DETAILED DESCRIPTION

[0057] It should be noted that the term "comprise" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or apparatus.

[0058] The "range" disclosed in the present invention is given in the form of a lower limit and an upper limit. It can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges defined in this way are combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, a range of 60-120 and 80-110 is listed for a particular parameter, and it is understood that a range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​listed are 1 and 2, and the maximum range values ​​listed are 3, 4, and 5, then the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0059] In the present invention, unless otherwise specified, the numerical range "ab" is an abbreviation for any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" are listed in this invention, and "0-5" is merely an abbreviation for these numerical combinations.

[0060] In the present invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form a new technical solution.

[0061] In the present invention, unless otherwise specified, all technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0062] In the present invention, unless otherwise specified, the term "two" used in this specification means "at least two".

[0063] In the present invention, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, the method comprising steps (a) and (b) indicates that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method further comprising step (c) indicates that step (c) may be added to the method in any order, for example, the method may comprise steps (a), (b) and (c), or may comprise steps (a), (c) and (b), or may comprise steps (c), (a) and (b), etc.

[0064] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and Examples. The following embodiments are part of the present invention, rather than all of the embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0065] Example 1

[0066] This embodiment provides a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles, which is prepared by a preparation method comprising the following steps:

[0067] Step 1: Add 1.5 mmol of Bi(NO3)3·5H2O and 5.4 mmol of NaH2PO4·2H2O to 60 mL of distilled water and stir magnetically at 25°C for 1 hour; then transfer the resulting mixed solution to a hydrothermal autoclave and react at 160°C for 24 hours. After the reaction, wash the mixture with deionized water and anhydrous ethanol by centrifugation for more than six times and dry it to obtain the final product, which is labeled as BiPO4.

[0068] Step 2: The BiPO4 obtained in the above step 1 was placed in a small porcelain boat and calcined in a tube furnace. The calcination conditions were: heating to 275°C at a heating rate of 3°C / min, constant temperature for 2h, atmosphere conditions H2:N2=5:95 (volume ratio), flow rate 50mL / min, and light gray powder was obtained after calcination, i.e., bismuth phosphate rich in oxygen defects, marked as BiPO 4-x .

[0069] Step 3: Add 0.3g of BiPO 4-xThe obtained mixture was dispersed in 60 mL of distilled water, and 0.37 g of Co(NO3)2·6H2O was added thereto and ultrasonically treated for 20 min. The obtained mixed solution was then stirred and evaporated in an 80°C water bath for 6 h. Finally, the obtained mixture was vacuum dried at 80°C for 12 h to obtain a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles, wherein the total weight of the oxygen-deficient bismuth phosphate nanorods was 100%, and the loading amount of the cobalt nanoparticles was 25 wt%.

[0070] The oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst was analyzed by scanning electron microscopy and transmission electron microscopy. The SEM and TEM images are shown as follows: Figure 1 and Figure 2 As shown. Figure 1 It can be seen that the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst is a nanorod structure with a length of about 300-400nm and a width of about 100-200nm, and the surface is loaded with cobalt nanoparticles with a size of 30-50nm. Figure 2 It can be seen that the results are consistent with the SEM characterization results, and the edges of the bismuth phosphate nanorods become disordered with a thickness of about 2.229 nm, indicating the presence of surface oxygen defects.

[0071] Example 2

[0072] This embodiment provides a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles, which is prepared by a preparation method comprising the following steps:

[0073] Step 1: Add 1.5 mmol of Bi(NO3)3·5H2O and 5.4 mmol of NaH2PO4·2H2O to 60 mL of distilled water and stir magnetically at 25°C for 1 hour; then transfer the resulting mixed solution to a hydrothermal autoclave and react at 160°C for 24 hours. After the reaction, wash the mixture with deionized water and anhydrous ethanol by centrifugation for more than six times and dry it to obtain the final product, which is labeled as BiPO4.

[0074] Step 2: The BiPO4 obtained in the above step 1 was placed in a small porcelain boat and calcined in a tube furnace. The calcination conditions were: heating to 275°C at a heating rate of 3°C / min, constant temperature for 2h, atmosphere conditions H2:N2=5:95 (volume ratio), flow rate 50mL / min, and light gray powder was obtained after calcination, i.e., bismuth phosphate rich in oxygen defects, marked as BiPO 4-x .

[0075] Step 3: Add 0.3g of BiPO 4-xThe obtained mixture was dispersed in 60 mL of distilled water, and 0.148 g of Co(NO3)2·6H2O was added thereto and ultrasonically treated for 20 min. The obtained mixed solution was then stirred and evaporated in an 80°C water bath for 6 h. Finally, the obtained mixture was vacuum dried at 80°C for 12 h to obtain an oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst, wherein the total weight of the oxygen-deficient bismuth phosphate nanorods was 100%, and the loading amount of the cobalt nanoparticles was 10 wt%.

[0076] Example 3

[0077] This embodiment provides a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles, which is prepared by a preparation method comprising the following steps:

[0078] Step 1: Add 1.5 mmol of Bi(NO3)3·5H2O and 5.4 mmol of NaH2PO4·2H2O to 60 mL of distilled water and stir magnetically at 25°C for 1 hour; then transfer the resulting mixed solution to a hydrothermal autoclave and react at 160°C for 24 hours. After the reaction, wash the mixture with deionized water and anhydrous ethanol by centrifugation for more than six times and dry it to obtain the final product, which is labeled as BiPO4.

[0079] Step 2: The BiPO4 obtained in the above step 1 was placed in a small porcelain boat and calcined in a tube furnace. The calcination conditions were: heating to 275°C at a heating rate of 3°C / min, constant temperature for 2h, atmosphere conditions H2:N2=5:95 (volume ratio), flow rate 50mL / min, and light gray powder was obtained after calcination, i.e., bismuth phosphate rich in oxygen defects, marked as BiPO 4-x .

[0080] Step 3: Add 0.3g of BiPO 4-x The obtained composite photocatalyst was prepared by dispersing the obtained composite photocatalyst in 60 mL of distilled water, adding 0.296 g of Co(NO3)2·6H2O thereto, and ultrasonically treating the obtained composite photocatalyst for 20 min. The obtained composite photocatalyst was evaporated by stirring in a water bath at 80°C for 6 h. The obtained composite photocatalyst was dried in a vacuum at 80°C for 12 h to obtain a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles. The total weight of the oxygen-deficient bismuth phosphate nanorods was 100%, and the loading amount of the cobalt nanoparticles was 20 wt%.

[0081] Example 4

[0082] This embodiment provides a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles, which is prepared by a preparation method comprising the following steps:

[0083] Step 1: Add 1.5 mmol of Bi(NO3)3·5H2O and 5.4 mmol of NaH2PO4·2H2O to 60 mL of distilled water and stir magnetically at 25°C for 1 hour; then transfer the resulting mixed solution to a hydrothermal autoclave and react at 160°C for 24 hours. After the reaction, wash the mixture with deionized water and anhydrous ethanol by centrifugation for more than six times and dry it to obtain the final product, which is labeled as BiPO4.

[0084] Step 2: The BiPO4 obtained in the above step 1 was placed in a small porcelain boat and calcined in a tube furnace. The calcination conditions were: heating to 275°C at a heating rate of 3°C / min, constant temperature for 2h, atmosphere conditions H2:N2=5:95 (volume ratio), flow rate 50mL / min, and light gray powder was obtained after calcination, i.e., bismuth phosphate rich in oxygen defects, marked as BiPO 4-x .

[0085] Step 3: Add 0.3g of BiPO 4-x The obtained mixture was dispersed in 60 mL of distilled water, and 0.444 g of Co(NO3)2·6H2O was added thereto and ultrasonically treated for 20 min. The obtained mixed solution was then stirred and evaporated in an 80°C water bath for 6 h. Finally, the obtained mixture was vacuum dried at 80°C for 12 h to obtain a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles, wherein the total weight of the oxygen-deficient bismuth phosphate nanorods was 100%, and the loading amount of the cobalt nanoparticles was 30 wt%.

[0086] Comparative Example 1

[0087] This comparative example provides a bismuth phosphate photocatalyst, which is prepared by a preparation method comprising the following steps:

[0088] 1.5 mmol of Bi(NO3)3·5H2O and 5.4 mmol of NaH2PO4·2H2O were added to a beaker containing 60 mL of distilled water and magnetically stirred for 1 hour. The resulting mixed solution was then transferred to a hydrothermal autoclave and reacted at 160°C for 24 hours. Finally, the mixture was washed three times with deionized water and anhydrous ethanol by centrifugation and dried to obtain a bismuth phosphate photocatalyst.

[0089] Comparative Example 2

[0090] This comparative example provides a bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst, which is prepared by a preparation method comprising the following steps:

[0091] Step 1: Add 1.5 mmol of Bi(NO3)3·5H2O and 5.4 mmol of NaH2PO4·2H2O to 60 mL of distilled water and stir magnetically at 25°C for 1 hour; then transfer the resulting mixed solution to a hydrothermal autoclave and react at 160°C for 24 hours. After the reaction, wash the mixture with deionized water and anhydrous ethanol by centrifugation for more than six times and dry it to obtain the final product, which is labeled as BiPO4.

[0092] Step 2: Disperse 0.3 g of BiPO4 prepared in step 1 in 60 mL of distilled water, add 0.37 g of Co(NO3)2·6H2O thereto, and ultrasonically treat for 20 minutes; then stir and evaporate the obtained mixed solution in an 80°C water bath for 6 hours; finally, vacuum dry the obtained mixture at 80°C for 12 hours to obtain a composite photocatalyst of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles, based on the total weight of the oxygen-deficient bismuth phosphate nanorods as 100%, and the loading amount of the cobalt nanoparticles is 25% wt.

[0093] The bismuth phosphate photocatalyst prepared in Comparative Example 1 was subjected to scanning electron microscopy analysis, and the SEM image thereof is as follows: Figure 3 As shown. Figure 3 It can be seen that the bismuth phosphate photocatalyst is a nanorod structure with a length of about 400-600 nm and a width of about 100-200 nm.

[0094] The bismuth phosphate nanorods loaded with cobalt nanoparticles composite photocatalyst prepared in Comparative Example 2 was analyzed by scanning electron microscopy. Figure 4 As shown. Figure 4 It can be seen that the photocatalyst is a nanorod structure with a length of about 300-400 nm and a width of about 100-200 nm, and the surface is loaded with cobalt nanoparticles with a size of 30-50 nm.

[0095] The N2 adsorption-desorption isotherms of the photocatalysts provided in Example 1, Comparative Example 1 and Comparative Example 2 are as follows: Figure 5 As shown. Figure 5 The results show that the specific surface area of ​​the bismuth phosphate photocatalyst prepared in Comparative Example 1 is only 5.4 m 2 / g, and the specific surface area of ​​the bismuth phosphate nanorods loaded with cobalt nanoparticles composite photocatalyst prepared in Comparative Example 2 is only 9.2 m 2 / g, while the specific surface area of ​​the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Example 1 of the present invention is 10.4 m 2 / g, which are 1.9 times the specific surface area of ​​the bismuth phosphate prepared in Comparative Example 1 and 1.13 times the specific surface area of ​​the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2.

[0096] Comparison of UV-visible diffuse reflectance spectra of the photocatalysts provided in Example 1, Comparative Example 1 and Comparative Example 2 Figure 6 As shown. Figure 6 It can be seen from the results that the absorption band edge of the bismuth phosphate photocatalyst prepared in Comparative Example 1 is about 290nm, the absorption band edge of the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2 is about 345nm, and the absorption band edge of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Example 1 is about 370nm, which greatly broadens the light absorption range of the material, and its light absorption intensity is also higher than the photocatalysts provided in Comparative Examples 1 and 2.

[0097] The band gap spectra of the photocatalysts provided in Example 1, Comparative Example 1 and Comparative Example 2 are compared. Figure 7 As shown. Figure 7 It can be seen from the results that the band gap width of the bismuth phosphate photocatalyst prepared in Comparative Example 1 is about 4.27 eV, the band gap width of the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2 is about 3.31 eV, and the band gap width of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Example 1 of the present invention is about 3.12 eV. The band gap energy becomes lower, and the energy required to excite electrons to migrate from the valence band to the conduction band becomes less, and it has higher chemical reaction activity.

[0098] Comparison of the O1s spectra of the photocatalysts provided in Example 1, Comparative Example 1 and Comparative Example 2 Figure 8 Show. Depend on Figure 8 It can be seen from the results that, relative to the content of each chemical state of O in the bismuth phosphate photocatalyst prepared in Comparative Example 1 and the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2, defective oxygen appears in the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Example 1 of the present invention. The participation of cobalt can induce the generation of surface oxygen defects, and the concentration of surface oxygen defects increases. In addition, oxygen defects can capture photogenerated electrons and improve the separation efficiency of photogenerated charges; while the bismuth phosphate photocatalyst prepared in Comparative Example 1 and the bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst prepared in Comparative Example 2 do not have surface oxygen defects.

[0099] Application Example 1

[0100] This application example uses tetracycline hydrochloride as the target pollutant to evaluate the degradation activity of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Examples 1 to 4. The evaluation process is carried out in the following specific manner:

[0101] 20 mg of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Examples 1 to 4 was added to 50 mL of tetracycline hydrochloride with an initial concentration of 50 ppm. Before the reaction began, adsorption was carried out under dark conditions. After reaching adsorption equilibrium, 0.5 mmol / L persulfate was added, and the light source was immediately turned on to react. The amounts of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst, tetracycline hydrochloride, and persulfate were 20 mg, 2.5 mg, and 15 mg, respectively, with a mass ratio of 8:1:6.

[0102] The persulfate is potassium peroxymonosulfate complex salt purchased from San Chemical Technology Co., Ltd., and its molecular formula is H3K5O 18 S4.

[0103] The light source is an LED light with a wavelength of 254 nm, a light power of 200 mW, and an intensity of 100 mW / cm 2 The reaction temperature was 20°C, the stirring speed was 500 rpm, and the light source was 5 cm away from the reaction liquid surface. During the 30-minute reaction time, samples were taken at predetermined time intervals and then immediately added to a centrifuge tube containing 1 mL of methanol to quench residual active species. The mixture was then centrifuged and the supernatant was collected. Finally, the absorbance was measured in sequence using a UV-visible spectrophotometer. In this application example, the absorbance intensity of the reaction solution at 350 nm (the maximum absorption wavelength of tetracycline hydrochloride) was measured to quantify its concentration change, and then compared with the original solution to obtain the relative percentage change of tetracycline hydrochloride.

[0104] According to the above steps, the activity of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Examples 1 to 4 was evaluated to obtain a curve showing the relationship between the removal rate of tetracycline hydrochloride and time. The experimental results are shown in FIG. Figure 9 As shown. Figure 9 It can be seen that the removal rates of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalysts provided in Examples 1 to 4 of the present invention for tetracycline hydrochloride can all reach over 90%, among which the photocatalyst provided in Example 1 has a removal rate of up to 99% for tetracycline hydrochloride. This indicates that the combination of photocatalysis and persulfate advanced oxidation technology can greatly improve the removal rate of tetracycline hydrochloride pollutants, thereby achieving the purpose of green and efficient removal of pollutants.

[0105] Comparative Application Example 1

[0106] In this comparative application example, the synergistic degradation of the bismuth phosphate photocatalyst and persulfate advanced oxidation technology provided in Comparative Example 1 was evaluated according to the evaluation method of Application Example 1, and a curve of the relationship between the removal rate of tetracycline hydrochloride and time was obtained. The curves of the relationship between the removal rate of tetracycline hydrochloride and time for the synergistic degradation of the bismuth phosphate photocatalyst and persulfate advanced oxidation technology provided in Example 1 using the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Example 1 and the bismuth phosphate photocatalyst provided in Comparative Example 1 in this comparative application example 1 were plotted on the same graph to more intuitively compare the two. The experimental results are shown in FIG. Figure 10 As shown. Figure 10 As shown in the results, when tetracycline hydrochloride is degraded in synergistically with the persulfate advanced oxidation technology, the removal rate of tetracycline hydrochloride by the bismuth phosphate photocatalyst provided in Comparative Example 1 is only 53%, while the removal rate of tetracycline hydrochloride by the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Example 1 of the present invention is as high as 99%, indicating that the performance of the catalyst provided in Example 1 of the present invention is better than that of the catalyst provided in Comparative Example 1.

[0107] Comparative Application Example 2

[0108] In this comparative application example, according to the evaluation method of application example 1, the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Example 1 was subjected to photocatalytic degradation evaluation without the addition of persulfate, and a curve showing the relationship between the removal rate of tetracycline hydrochloride and time was obtained. The curve showing the relationship between the removal rate and time of tetracycline hydrochloride synergistically degraded by the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst and persulfate advanced oxidation technology provided in Example 1 and the curve showing the relationship between the removal rate and time of tetracycline hydrochloride photocatalytically degraded by the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst provided in Example 1 in this comparative application example 2 were plotted on the same graph to more intuitively compare the two. The experimental results are shown in FIG. Figure 11 As shown. Figure 11 The results shown in show that, without the addition of persulfate, the removal rate of tetracycline hydrochloride by the oxygen-deficient bismuth phosphate nanorod-supported cobalt nanoparticle composite photocatalyst provided in Example 1 was only 31%. After the addition of persulfate, the synergistic degradation of tetracycline hydrochloride using the oxygen-deficient bismuth phosphate nanorod-supported cobalt nanoparticle composite photocatalyst provided in Example 1 of the present invention, combined with the persulfate advanced oxidation technology, achieved a tetracycline hydrochloride removal rate of 99%. This demonstrates that the combination of photocatalysis and persulfate advanced oxidation technology can significantly improve the removal rate of tetracycline hydrochloride pollutants, achieving the goal of green and efficient pollutant removal.

[0109] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, substitutions of equivalent components, or equivalent changes and modifications made within the scope of patent protection, should still fall within the scope of this patent. Furthermore, the technical features of this invention may be freely combined with one another, with other technical inventions, and with other technical inventions.

Claims

1. An application of a composite photocatalyst of bismuth phosphate nanorods loaded with cobalt nanoparticles rich in oxygen defects in the degradation of antibiotics by synergistic action of photocatalysis and persulfate advanced oxidation technology, characterized in that: The composite photocatalyst comprises oxygen-deficient bismuth phosphate nanorods and cobalt nanoparticles loaded on the surface of the oxygen-deficient bismuth phosphate nanorods; Based on the total weight of the oxygen-deficient bismuth phosphate nanorods as 100%, the loading amount of the cobalt nanoparticles is 5-30wt%; The oxygen-deficient bismuth phosphate nanorods have a one-dimensional structure of nanorods, a length of 300-400 nm, and a width of 100-200 nm.

2. The use according to claim 1, characterized in that The antibiotics include tetracycline hydrochloride.

3. The use according to claim 1, characterized in that The size of the cobalt nanoparticles is 30-50 nm.

4. The use according to any one of claims 1 to 3, characterized in that The preparation method of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst comprises: Step 1: Add bismuth salt and phosphate into water, mix well and then conduct hydrothermal reaction to obtain BiPO4; Step 2: calcining BiPO4 at high temperature in a hydrogen-nitrogen mixed gas or hydrogen-argon mixed gas atmosphere to obtain BiPO 4-x ; Step 3: BiPO 4-x The bismuth phosphate nanorods rich in oxygen defects and the cobalt source are dissolved in water, mixed evenly and then evaporated in a water bath to obtain the cobalt nanoparticle-loaded composite photocatalyst.

5. The use according to claim 4, characterized in that The bismuth salt includes bismuth nitrate and / or bismuth chloride; The phosphate includes one or a combination of sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, and potassium phosphate.

6. The use according to claim 4, characterized in that In step 1, the temperature of the hydrothermal reaction is 120-200° C., and the time is 12-36 hours.

7. The use according to claim 4, characterized in that In step 1, the uniform mixing is achieved by constant temperature stirring, the temperature is 10-50° C., and the stirring time is 1-10 h.

8. The use according to claim 4, characterized in that In step 2, the volume ratio of hydrogen in the hydrogen-nitrogen mixture or hydrogen-argon mixture atmosphere is 5-20%, and the flow rate of the hydrogen-nitrogen mixture or hydrogen-argon mixture is 30-100 mL min -1 .

9. The use according to claim 4, characterized in that In step 2, the high-temperature calcination includes heating the temperature to 200-350° C. at a heating rate of 1-5° C. / min and calcining for 1-4 hours.

10. The use according to claim 4, characterized in that In step 3, the temperature of the water bath evaporation is 40-100° C. and the time is 4-10 h.

11. The use according to claim 4, characterized in that In step three, the cobalt source includes cobalt nitrate and / or cobalt chloride.

12. The use according to claim 11, characterized in that The cobalt source is cobalt nitrate.

13. A method for degrading antibiotics by synergistic action of photocatalysis and persulfate advanced oxidation technology, characterized in that: The method comprises the following steps: A composite photocatalyst composed of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles was added to the target pollutant containing antibiotics. After adsorption equilibrium was reached in the dark, persulfate was added and a light source was turned on to react. After the reaction was completed, the antibiotics were degraded. The composite photocatalyst comprises oxygen-deficient bismuth phosphate nanorods and cobalt nanoparticles loaded on the surface of the oxygen-deficient bismuth phosphate nanorods; Based on the total weight of the oxygen-deficient bismuth phosphate nanorods as 100%, the loading amount of the cobalt nanoparticles is 5-30wt%; The oxygen-deficient bismuth phosphate nanorods have a one-dimensional structure of nanorods, a length of 300-400 nm, and a width of 100-200 nm.

14. The method according to claim 13, characterized in that The light source is an LED lamp.

15. The method according to claim 14, characterized in that The power of the LED light is 100-500mW, the wavelength is 254nm, and the intensity is 50-150mW / cm 2 , the light source is 3-25cm away from the reaction liquid surface.

16. The method according to claim 13, characterized in that The reaction temperature is 10-80°C.

17. The method according to claim 13, wherein The mass ratio of oxygen-deficient bismuth phosphate nanorods loaded with cobalt nanoparticles composite photocatalyst, antibiotics and persulfate is 8:1:6-8:1:

12.

18. The method according to any one of claims 13 to 17, characterized in that: The antibiotics include tetracycline hydrochloride.

19. The method according to claim 13, wherein The size of the cobalt nanoparticles is 30-50 nm.

20. The method according to claim 13 or 19, characterized in that The preparation method of the oxygen-deficient bismuth phosphate nanorod-loaded cobalt nanoparticle composite photocatalyst comprises: Step 1: Add bismuth salt and phosphate into water, mix well and then conduct hydrothermal reaction to obtain BiPO4; Step 2: calcining BiPO4 at high temperature in a hydrogen-nitrogen mixed gas or hydrogen-argon mixed gas atmosphere to obtain BiPO 4-x ; Step 3: BiPO 4-x The bismuth phosphate nanorods rich in oxygen defects and the cobalt source are dissolved in water, mixed evenly and then evaporated in a water bath to obtain the cobalt nanoparticle-loaded composite photocatalyst.

21. The method according to claim 20, characterized in that The bismuth salt includes bismuth nitrate and / or bismuth chloride; The phosphate includes one or a combination of sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, and potassium phosphate.

22. The method according to claim 20, characterized in that In step 1, the temperature of the hydrothermal reaction is 120-200° C., and the time is 12-36 hours.

23. The method according to claim 20, characterized in that In step 1, the uniform mixing is achieved by constant temperature stirring, the temperature is 10-50° C., and the stirring time is 1-10 h.

24. The method according to claim 20, characterized in that In step 2, the volume ratio of hydrogen in the hydrogen-nitrogen mixture or hydrogen-argon mixture atmosphere is 5-20%, and the flow rate of the hydrogen-nitrogen mixture or hydrogen-argon mixture is 30-100 mL min -1 .

25. The method according to claim 20, wherein In step 2, the high-temperature calcination includes heating the temperature to 200-350° C. at a heating rate of 1-5° C. / min and calcining for 1-4 hours.

26. The method according to claim 20, wherein In step 3, the temperature of the water bath evaporation is 40-100° C. and the time is 4-10 h.

27. The method according to claim 20, characterized in that In step three, the cobalt source includes cobalt nitrate and / or cobalt chloride.

28. The method according to claim 27, characterized in that The cobalt source is cobalt nitrate.

Images