A photocatalyst with near-infrared light response and a preparation method and application thereof

Abstract

The application discloses a photocatalyst with near-infrared light response and a preparation method and application thereof, and the catalyst is composed of BiO 2‑X / Ag2O. The preparation process comprises the following steps: adding NaOH solid into deionized water to form a clear solution, adding AgNO3 and NaBiO3 in sequence, carrying out hydrothermal reaction at 180 DEG C for 4-18 hours, and obtaining the catalyst through separation, water washing and drying. The BiO 2‑X / Ag2O photocatalytic material has strong near-infrared light absorption capacity, and has obvious synergistic effect between BiO 2‑X and Ag2O, so that the near-infrared light catalytic activity of the catalyst is obviously improved, excellent photo-generated charge separation efficiency is obtained, abundant oxidation free radicals can be generated, and tetracycline pollutants can be efficiently and quickly degraded under near-infrared light irradiation.

Description

TECHNICAL FIELD

[0001] The present application relates to photocatalysts and wastewater treatment, in particular to a photocatalyst with near-infrared light response and a preparation method and application thereof. BACKGROUND

[0002] In recent years, tetracycline drugs have been widely used in medical, agricultural, livestock and food industry fields, resulting in a large amount of antibiotics being discharged into the water environment. In China, tetracycline has been detected in urban sewage inlets, groundwater and rivers. The presence of tetracycline in water bodies will pose a potential threat to the growth of aquatic organisms and human health. Therefore, it is of great significance to explore efficient antibiotic treatment technologies.

[0003] Traditional tetracycline treatment methods include adsorption, biodegradation, membrane treatment and advanced oxidation. Photocatalysis is a green and efficient organic pollutant treatment technology, which is a process of removing organic pollutants in water bodies by absorbing solar energy through semiconductor materials. Because of its simple operation, low consumption and no secondary pollution, it has become one of the hot topics in the treatment of tetracycline pollutants in water bodies.

[0004] Light absorption efficiency is one of the key factors affecting the photocatalytic degradation of tetracycline activity. At present, most of the reported photocatalytic materials have ultraviolet or visible light response, but the reaction activity under near-infrared light is very low. In sunlight, near-infrared light accounts for 49%. Therefore, the preparation of photocatalytic materials with near-infrared absorption ability will further improve the efficient removal of tetracycline in water bodies. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application provides a photocatalyst with near-infrared light response and a preparation method and application thereof, and the photocatalyst is composed of BiO 2-X / Ag2O, which has near-infrared light response and excellent photo-induced charge separation efficiency, and can efficiently and rapidly degrade tetracycline and other organic pollutants under near-infrared light irradiation.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0007] A photocatalyst with near-infrared light response, which is composed of BiO 2-X / Ag2O.

[0008] The preparation method of the above-mentioned photocatalyst with near-infrared light response comprises the following steps:

[0009] S1, dissolving an alkaline oxide in deionized water and stirring to obtain a clear solution;

[0010] S2, adding silver salt into the solution obtained in step S1 to form a heterogeneous reaction solution;

[0011] S3, adding bismuth salt into the reaction solution obtained in step S2 and stirring at room temperature;

[0012] S4, high-temperature reaction of the reaction solution in step S3, filtration and drying to obtain a photocatalyst with near-infrared light response.

[0013] Further, in step S1, the basic oxide is at least one of sodium hydroxide and potassium hydroxide.

[0014] Further, in step S2, the silver salt is silver nitrate, and the heterogeneous reaction solution is a reaction solution containing silver hydroxide.

[0015] Further, in step S3, the bismuth salt is sodium bismuthate, the molar ratio of bismuth salt to basic oxide is 1:(5-7), more preferably 1:6; the molar ratio of silver salt to bismuth salt is 1:(1-6), more preferably 1:4; and the magnetic stirring time is 20-60 min.

[0016] Further, in step S4, the high-temperature reaction temperature is 160-180℃, and the time is 10-18h; the drying temperature is 50-70℃, and the time is 5-8h.

[0017] The above-mentioned photocatalyst with near-infrared light response can be applied to organic pollutant degradation.

[0018] Further, the specific method is to add the photocatalyst with near-infrared light response into a water body containing organic pollutants to perform a photodegradation reaction, thereby completing the degradation of the organic pollutants in the water body.

[0019] Further, the addition amount of the photocatalyst with near-infrared light response is 0.4-1.5mg / mL of the water body, preferably 0.8-1.2mg / mL of the water body; and the photodegradation reaction is performed under a xenon lamp equipped with a filter.

[0020] Further, the wavelength of the filter is greater than 780nm.

[0021] Further, the organic pollutants are tetracycline drugs; the initial concentration of the organic pollutants in the water body is 8-20mg / L; and the degradation reaction time is 5-120min, preferably 60-120min.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] (1) In the catalyst of the present application, BiO 2-X and Ag2O can absorb near-infrared light as a single component, and the 2D sheet structure of BiO 2-XThis provides abundant sites and spaces for the attachment of Ag₂O nanoparticles. Therefore, under high-temperature hydrothermal action, a large amount of Ag₂O can adhere to BiO₂. 2-X Surface formation results in a heterojunction interface. Due to BiO 2-X BiO has a different composition, band gap width, and dielectric constant than Ag₂O crystals. Positive charges are concentrated on the Ag₂O side, while negative charges are concentrated on the BiO side. 2-X On one side, thus in Ag2O / BiO 2-X An internal electric field is generated at the interface. When BiO 2-X When both Ag₂O and BiO are photoexcited simultaneously, the photogenerated electrons and holes are rapidly separated under the influence of the internal electric field, causing the electrons and holes to move to Ag₂O and BiO, respectively. 2-X Semiconductor surface. Furthermore, the formation of a large amount of Ag₂O can enhance the performance of BiO₂. 2-X The near-infrared light absorption capacity further promotes the generation of high-concentration oxidizing active species, ensuring the efficient and continuous degradation of organic pollutants such as tetracycline in water during photocatalysis, thus exhibiting the characteristics of BiO2. 2-X The significant synergistic effect between Ag₂O and the catalyst significantly enhances its near-infrared photocatalytic activity. The photocatalyst of this invention possesses advantages such as strong near-infrared light response, good stability, and environmental friendliness. It can efficiently and rapidly degrade tetracycline pollutants under near-infrared light irradiation, exhibiting good reproducibility and promising application prospects.

[0024] (2) The preparation method of the present invention uses sodium bismuthate and silver salt as raw materials, mixes them in sodium hydroxide solution, stirs at room temperature and carries out hydrothermal reaction. The resulting catalyst has the advantages of strong near-infrared light response, good stability and excellent catalytic performance. Moreover, the process is simple, easy to operate and has good repeatability, making it suitable for large-scale preparation.

[0025] (3) The catalyst obtained by this invention can very effectively degrade organic pollutants in water, such as tetracycline pollutants in water. By dispersing the photocatalyst in the tetracycline pollutant water, the tetracycline pollutants in the water can be degraded under near-infrared light irradiation. It has the advantages of being green (light energy), having mild reaction conditions (carried out at room temperature), low treatment cost, and high treatment efficiency. It can be widely used to degrade different organic pollutants in water (such as organic dyes, chemical reagents, and organic drugs), and has a wide range of applications. Attached Figure Description

[0026] Figure 1 The image shows the XRD pattern of the near-infrared photocatalyst prepared in Example 1 of this invention.

[0027] Figure 2 The TEM image of the near-infrared light-responsive photocatalyst prepared in Example 1 of the present invention is shown in Figure (the magnification of Figure (b) is 50 times that of Figure (a)).

[0028] Figure 3 DRS graph of the near-infrared light responsive photocatalyst prepared in Embodiment 1 of the present application.

[0029] Figure 4 Time-degradation efficiency graph corresponding to the degradation of tetracycline pollutants by the catalyst prepared in Embodiment 2 of the present application under near-infrared light.

[0030] Figure 5 Degradation principle diagram of the near-infrared light responsive photocatalyst of the present application.

[0031] Figure 6 Time-degradation efficiency graph corresponding to the degradation of tetracycline by different catalysts in Embodiment 3 of the present application under near-infrared light.

[0032] Figure 7 Time-degradation efficiency graph corresponding to the degradation of different organic pollutants by the catalyst in Embodiment 4 of the present application under near-infrared light.

[0033] Figure 8 Cycle number-degradation efficiency graph corresponding to the degradation of tetracycline pollutants by the catalyst in Embodiment 5 of the present application under near-infrared light. DETAILED DESCRIPTION

[0034] The present application is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present application is not limited thereby.

[0035] In the following embodiments of the present application, the materials and instruments used are commercially available, the processes used are conventional processes, and the equipment used is conventional equipment, unless otherwise specified.

[0036] Embodiment 1

[0037] A near-infrared light responsive photocatalyst, consisting of BiO 2-x / Ag2O.

[0038] The preparation method of the above catalyst comprises the following steps:

[0039] (1) 2.4 g of NaOH solid was dissolved in 60 mL of water, and stirred to dissolve to obtain a clear solution. Under magnetic stirring, 68 mg of AgNO3 solid was added, and immediately solid precipitate (Ag(OH)2) was generated. Then 2.8 g of NaBiO3 solid was added, and ultrasonic dispersion was performed, thereby obtaining the reaction system of the present application.

[0040] (2) The reaction solution obtained in step (1) is stirred continuously at room temperature for 30-60 min, then transferred to a reaction vessel and heated to 180°C for 18 h; after the reaction is completed, the mixture is washed with water, washed with ethanol, filtered, and dried to obtain near-infrared responsive BiO. 2-x / Ag2O photocatalyst.

[0041] Figure 1 The near-infrared light-responsive BiO prepared in Example 1 of this invention 2-x XRD pattern of Ag₂O photocatalyst. Figure 1 It can be seen that all characteristic peaks are sharp, and the peak positions correspond to BiO₂. 2-x The absence of other impurity peaks in the Ag₂O single crystal indicates that the prepared substance is BiO. 2-x It is an Ag2O complex with good crystallinity.

[0042] Figure 2 The near-infrared light-responsive BiO prepared in Example 1 of this invention 2-x TEM image of Ag₂O photocatalyst. Figure 2 It can be seen that the BiO prepared under the reaction conditions of Example 1 2-x It has a nanosheet structure, with small particles of Ag₂O distributed within BiO. 2-x The surface of the nanosheets. Furthermore, the lattice and layered interface of the two materials are clearly observed in the high-magnification TEM image (Figure (b)), indicating that BiO... 2-x The / Ag2O complex forms a heterojunction interface.

[0043] Figure 3 The near-infrared light-responsive BiO prepared in Example 1 of this invention 2-x DRS diagram of Ag₂O photocatalyst. Figure 3 It can be seen that BiO 2-x The / Ag2O complex exhibits light absorption in the wavelength range of 200–2000 nm, and compared to BiO... 2-x It exhibits higher light absorption intensity in the near-infrared wavelength range (780–2000 nm), indicating that Ag₂O nanoparticles enhance the absorption of BiO₂. 2-x The absorption capacity of nanosheets for near-infrared light.

[0044] Example 2

[0045] A BiO with near-infrared light response 2-x The application of Ag2O photocatalysts in the degradation of organic pollutants specifically involves utilizing BiO2, which has a near-infrared light response. 2-x Ag2O photocatalyst degrades organic pollutants in water, including the following steps:

[0046] Take 20 mg of the BiO 2-x / Ag2O photocatalyst prepared in Example 1, ultrasonically disperse in 50 mL of a tetracycline aqueous solution with a concentration of 10 mg / L, before light irradiation, the above solution is magnetically stirred for 30 min in the dark, so that the tetracycline achieves adsorption-desorption equilibrium on the surface of the catalyst. A xenon lamp (300 W) equipped with a filter with a wavelength of >780 nm is used to carry out the photodegradation reaction to complete the degradation of the organic pollutants in the water body.

[0047] During the degradation process, the concentration of the solution is determined at different reaction times (30 min, 60 min, 90 min, and 120 min), and the degradation efficiency of tetracycline is calculated, and the results are shown in Table 1. Figure 4

[0048] Figure 4 BiO 2-x / Ag2O photocatalyst in Example 2 is used to degrade tetracycline in water. The corresponding time-degradation effect diagram is shown in Figure 2. Figure 4 As can be seen from Figure 2, after 120 min of light irradiation, the removal efficiency of tetracycline by the BiO 2-x / Ag2O photocatalyst reaches 82%, which indicates that the catalyst has a high degradation effect on tetracycline pollutants under near-infrared light.

[0049] Figure 5 The degradation principle diagram of the BiO Figure 5 As can be seen from Figure 3, under near-infrared light irradiation, the electrons in BiO 2-x and Ag2O jump and migrate to their respective conduction bands; the original position forms a positively charged hole due to the loss of electrons and is enriched in the respective valence band. At the heterojunction interface generated after the contact of BiO 2-x and Ag2O, the electrons and holes with higher potential will migrate to the position with lower potential through the interface. Therefore, a large number of electrons are enriched in the conduction band of BiO 2-x , and holes are gathered in the valence band of Ag2O. The holes have oxidation ability and can directly degrade tetracycline pollutants; the electrons with reduction ability react with dissolved oxygen in water to generate ·O2 - , and ·OH is further generated by the reaction of ·O2 - and water, under the joint action of ·O2 - and ·OH, tetracycline pollutants are rapidly removed; at the same time, the heterojunction interface promotes the effective migration of electrons and holes, thereby realizing the generation of high-concentration oxidation active species and ensuring the continuous and efficient degradation of tetracycline pollutants in water.

[0050] Example 3

[0051] ​The influence of different composition catalysts on the degradation performance of tetracycline pollutants is investigated, including the following steps:

[0052] 20 mg of the prepared BiO 2-x / Ag2O photocatalyst with near-infrared light response in Example 1 is weighed and ultrasonically dispersed in 50 mL of a tetracycline aqueous solution with a concentration of 10 mg / L. Before the photodegradation reaction, the above solution is magnetically stirred in the dark for 30 min to achieve adsorption-desorption equilibrium of tetracycline on the surface of the catalyst. A xenon lamp equipped with a filter with a wavelength of >780 nm is used to perform the photodegradation reaction to complete the degradation of organic pollutants in the water body.

[0053] BiO 2-x , Ag2O, WO 3-x , Ag2S, and Cu2S are respectively used to replace the BiO 2-x / Ag2O photocatalyst in Example 1, and the tetracycline solution is subjected to photodegradation under the same conditions.

[0054] During the degradation reaction, the concentration of the solution is determined at different reaction times (30 min, 60 min, 90 min, and 120 min), and the degradation efficiency of tetracycline is calculated, as shown in Table 1. Figure 6

[0055] Figure 6 The degradation of the tetracycline solution by the different composition catalysts in Example 3 is the corresponding time-degradation effect diagram, as shown in Table 2. Figure 6 As can be seen from Table 2, under the irradiation of a xenon lamp with a wavelength of >780 nm, the degradation performance of the BiO 2-x / Ag2O photocatalyst with near-infrared light response on tetracycline is significantly higher than that of other near-infrared light response photocatalysts. This is mainly because BiO 2-x / Ag2O has stronger near-infrared light absorption, can generate more electrons and holes, and the potential difference between BiO 2-x and Ag2O and the heterojunction interface promote the effective migration and separation of electrons and holes, thereby significantly increasing the concentration of surface oxidative active species and achieving efficient degradation of tetracycline pollutants.

[0056] Example 4

[0057] The application of a photocatalyst with near-infrared light response in degrading organic pollutants, specifically the degradation of organic pollutants in water bodies by using a BiO 2-x / Ag2O photocatalyst with near-infrared light response, includes the following steps:

[0058] ​Three portions (20 mg each) of the near-infrared photocatalyst prepared in Example 1 were weighed and added to 50 mL of a 10 mg / L Rhodamine B solution and 50 mL of a 10 mg / L methyl orange solution, respectively. Before the photocatalytic reaction, the solutions were magnetically stirred for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on the catalyst surface. The photodegradation reaction was carried out using a xenon lamp (300 W) equipped with a λ > 780 nm filter to complete the degradation of organic dyes in the water.

[0059] During the degradation reaction, solutions with different reaction times (30 min, 60 min, 90 min, 120 min) were taken for concentration determination, and the degradation efficiency of Rhodamine B and methyl orange was calculated. The results are as follows: Figure 7 As shown.

[0060] Figure 7 The graph shows the time-degradation efficiency of the near-infrared photocatalyst used in Example 4 of this invention for the degradation of Rhodamine B and methyl orange in water. Figure 7 It can be seen that within 120 minutes, the near-infrared light-responsive photocatalyst of the present invention achieved a degradation efficiency of over 80% for both Rhodamine B and methyl orange under near-infrared light, which indicates that the catalyst of the present invention also has a good removal effect on different organic dye pollutants.

[0061] Example 5

[0062] The reusability of the near-infrared light-responsive photocatalyst of this invention for degrading organic pollutants was investigated, including the following steps:

[0063] (1) Weigh 20 mg of the near-infrared photocatalyst prepared in Example 1 and add it to 50 mL of a tetracycline solution with a concentration of 10 mg / L. Before the photocatalytic reaction, the solution is magnetically stirred for 30 min in the dark to allow the tetracycline to achieve adsorption-desorption equilibrium on the catalyst surface. A xenon lamp (300 W) equipped with a λ > 780 nm filter is used to carry out the photodegradation reaction to complete the degradation of tetracycline pollutants in the water.

[0064] (2) After the degradation reaction is completed, the photocatalyst in the reaction system of step (1) is collected through a filter membrane, washed and dried, and the resulting near-infrared light responsive photocatalyst is used to degrade tetracycline pollutants in water.

[0065] (3) Repeat steps (1) to (2) three times in total. That is, use the near-infrared photocatalyst prepared in Example 1 to complete four degradation experiments on tetracycline solution.

[0066] Figure 8The figure of the corresponding cycle number-degradation effect when the near-infrared light responsive photocatalyst in Embodiment 5 repeatedly degrades tetracycline solution. From the figure, it can be seen that the degradation efficiency of the near-infrared light responsive photocatalyst of the present application on tetracycline pollutants still remains at 72% after four repeated degradations, which indicates that the near-infrared light responsive photocatalyst prepared in the present application has high light stability and can be repeatedly used. Figure 8 The figure of the corresponding cycle number-degradation effect when the near-infrared light responsive photocatalyst in Embodiment 5 repeatedly degrades tetracycline solution. From the figure, it can be seen that the degradation efficiency of the near-infrared light responsive photocatalyst of the present application on tetracycline pollutants still remains at 72% after four repeated degradations, which indicates that the near-infrared light responsive photocatalyst prepared in the present application has high light stability and can be repeatedly used.

Claims

1. A photocatalyst having a near-infrared light response, characterized by comprising: The composition of the near-infrared light responsive photocatalyst is BiO 2-X / Ag2O, and the preparation method of the near-infrared light responsive photocatalyst comprises the following steps: S1, dissolving the alkaline hydroxide in deionized water, stirring to obtain a clear solution; S2, adding silver salt to the solution obtained in step S1 to form a heterogeneous reaction solution; S3, adding bismuth salt to the reaction solution obtained in step S2, stirring at room temperature; S4, high temperature reaction of the reaction solution in step S3, the temperature of high temperature reaction is 160-180℃, the time is 10-18h, filtering and drying to obtain a near-infrared light responsive photocatalyst; Wherein, the molar ratio of bismuth salt and alkaline hydroxide is 1: (5-7), the molar ratio of silver salt and bismuth salt is 1: (1-6), and the alkaline hydroxide is at least one of sodium hydroxide and potassium hydroxide.

2. A method for preparing a near-infrared light-responsive photocatalyst as described in claim 1, characterized in that, The steps are: S1, dissolving the alkaline hydroxide in deionized water, stirring to obtain a clear solution; S2, adding silver salt to the solution obtained in step S1 to form a heterogeneous reaction solution; S3, adding bismuth salt to the reaction solution obtained in step S2, stirring at room temperature; S4, high temperature reaction of the reaction solution in step S3, the temperature of high temperature reaction is 160-180℃, the time is 10-18h, filtering and drying to obtain a near-infrared light responsive photocatalyst; Wherein, the molar ratio of bismuth salt and alkaline hydroxide is 1: (5-7), the molar ratio of silver salt and bismuth salt is 1: (1-6), and the alkaline hydroxide is at least one of sodium hydroxide and potassium hydroxide.

3. The preparation method according to claim 2, characterized in that, In step S2, the silver salt is silver nitrate, and the heterogeneous reaction solution contains silver hydroxide.

4. The production method according to claim 2 or 3, characterized by, In step S3, the bismuth salt is sodium bismuthate, and the stirring time is 20-60 min.

5. The production method according to claim 2 or 3, characterized by, In step S4, the drying temperature is 50-70℃, and the time is 5-8h.

6. The application of the near-infrared light responsive photocatalyst of claim 1 or the near-infrared light responsive photocatalyst prepared by the preparation method of any one of claims 2 to 5 in degrading organic pollutants in water.

7. Use according to claim 6, characterized in that, The application comprises the following steps: adding the near-infrared light responsive photocatalyst to the water body containing organic pollutants to carry out a photodegradation reaction, and completing the degradation of the organic pollutants in the water body.

8. Use according to claim 7, characterized in that, The addition amount of the near-infrared light responsive photocatalyst is 0.4-1.5 mg / mL of the water body; the photodegradation reaction is carried out under a xenon lamp equipped with a filter; the wavelength of the filter is greater than 780 nm.

9. Use according to any one of claims 6 to 8, characterized in that, The organic pollutants are tetracycline drugs; the initial concentration of the organic pollutants in the water body is 8-20 mg / L; and the degradation reaction time is 5-120 min.

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