A titanium-lanthanum composite banana peel carbon-based photocatalyst, its preparation method and application

Abstract

A titanium-lanthanum composite banana peel carbon-based photocatalyst, its preparation method, and its application are disclosed, relating to the field of photocatalyst material synthesis technology. The photocatalyst, TiO2-LaOCl@BC, is generated by reacting banana peel carbon (BC), lanthanum nitrate, and titanium dioxide under heating conditions. The microstructure shows that TiO2 and LaOCl are uniformly dispersed on the BC surface, with LaOCl chemically coated onto the BC surface, and TiO2 and LaOCl@BC are uniformly mixed. The composite photocatalyst prepared in this invention exhibits close contact between its components, which is beneficial for the transport and separation of photogenerated electrons and holes. Its performance is superior to commercial titanium dioxide, standard carbon-based photocatalyst g-C3N4, and conventional carbon modified with titanium-lanthanum. Under visible light in pure water (without sacrificial agents), it can degrade organic dyes into small molecules, purifying and decolorizing the dyes, with a degradation rate constant K*100 as high as 4.8 min. ‑1 .

Description

Technical Field

[0001] This invention relates to the field of photocatalyst material synthesis technology, specifically to a titanium-lanthanum composite banana peel carbon-based photocatalyst, its preparation method, and its application. Background Technology

[0002] The titanium-lanthanum system refers to a photocatalytic system in which the transition metal element titanium and the rare earth element lanthanum coexist. The core advantage of the titanium-lanthanum system lies in the unique 4f electronic structure of lanthanum-based elements and compounds, which possess distinctive photoelectric properties, making them ideal dopants. Doping or compounding with titanium materials, which also exhibit excellent photocatalytic performance, helps promote the separation and transfer of photogenerated carriers and allows for the adjustment of active groups. The f-orbitals of lanthanides can combine with Lewis matrices (acids, amines, aldehydes, alcohols, and thiols, etc.). This combination in the titanium-lanthanum system can adsorb organic pollutants onto the photocatalyst surface, significantly improving its catalytic efficiency. However, its industrial development is limited by problems such as the low absorption threshold of single photocatalysts, low ultraviolet light utilization, easy recombination of photogenerated electrons and holes, and unsatisfactory practical application results.

[0003] Lanthanum chloride oxide (LaOCl) is a lanthanide compound, a p-type semiconductor with a tetragonal structure, and has been widely used in optical devices, thermocatalysis, and sensors. Due to its high affinity for water molecules and pre-activation ability, it possesses significant theoretical advantages in the photocatalytic degradation of organic pollutants in water. However, the absorption of light from 200 to 600 nm by pure LaOCl at normal ambient temperatures is negligible, which severely limits its application in the photocatalytic degradation of organic pollutants.

[0004] Benefiting from the experience gained with the lanthanum titanium system, it can be doped with titanium dioxide, a titanium element material whose photocatalytic capabilities are widely recognized. Currently, the doping of the lanthanum titanium system mainly adopts the sol-gel method. This process requires the use of expensive titanium alkoxides (such as tetrabutyl titanate) and large amounts of organic solvents (such as methanol and ethanol) as raw materials and synthesis media. Moreover, the products suffer from problems such as agglomeration, non-uniform size, low specific surface area, and poor chemical homogeneity. These problems make it difficult to improve the photocatalytic performance of LaOCl composite TiO2, which greatly hinders the upper limit of its industrial development. Therefore, it is of great significance to develop a novel, simple, efficient, readily available, low-cost, environmentally friendly, high-purity, high-performance, and easily industrialized synthesis method for the lanthanum titanium system (TiO2-LaOCl). Summary of the Invention

[0005] The purpose of this invention is to solve the problems of cumbersome preparation methods, high price, high energy consumption, high pollution, low purity, and poor performance homogeneity of current titanium-lanthanum systems. This invention provides a titanium-lanthanum system composite banana peel carbon-based photocatalyst, its preparation method, and its application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a titanium-lanthanum composite banana peel carbon-based photocatalyst, which utilizes the reaction of banana peel carbon (BC), lanthanum nitrate, and titanium dioxide under heating conditions to generate a TiO2-LaOCl@BC photocatalyst, specifically includes the following steps:

[0008] ① After drying the banana peel, crush it with a pulverizer, then place it in a heating furnace. Under the protection of inert gas, heat the temperature to 500-800℃ at a rate of 5-20℃ / min and hold it at that temperature for 0.1-10 hours for carbonization. Then, perform acid soaking, filtration, water washing, and drying to obtain banana peel carbon BC.

[0009] ② Mix banana peel carbon BC, lanthanum nitrate and titanium dioxide in a molar ratio of 600:1~20:1~20, and then transfer the mixed powder to a heating furnace;

[0010] ③ Under the protection of inert gas, the heating furnace is heated to 500-800℃ at a heating rate of 5-20℃ / min and held at that temperature for 0.1-10h;

[0011] ④ After the heating reaction is complete, the product is removed to obtain the titanium-lanthanum composite banana peel carbon-based photocatalyst TiO2-LaOCl@BC.

[0012] As a preferred technical solution for the above preparation method, the drying in step ① includes atmospheric pressure drying, freeze drying, or vacuum drying. The uniform mixing method in step ② includes mechanical ball milling, mechanical stirring, and manual grinding. The inert gas in steps ① and ③ is one or more mixtures of nitrogen, argon, and helium.

[0013] The titanium-lanthanum composite banana peel carbon-based photocatalyst proposed in this invention can be applied in the field of photocatalytic degradation of organic dyes and exhibits excellent catalytic activity. Its microstructure is as follows: TiO2 and LaOCl are uniformly dispersed on the BC surface, wherein LaOCl is chemically coated on the BC surface, and TiO2 and LaOCl@BC are uniformly mixed.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] (1) In the TiO2-LaOCl@BC structure prepared by this invention, TiO2 and LaOCl are uniformly dispersed on the BC surface, wherein LaOCl is coated on the BC surface through a chemical reaction, and TiO2 and LaOCl@BC are uniformly mixed. The components in the prepared composite photocatalyst have close contact, which is beneficial to the transport and separation of photogenerated electrons and holes, and the preparation process is simple and low in cost.

[0016] (2) The TiO2-LaOCl@BC prepared in this invention exhibits superior performance compared to commercial titanium dioxide, standard carbon-based photocatalyst g-C3N4, and conventional carbon modified with titanium lanthanum. Under visible light in pure water (without sacrificial agents), it can degrade organic dyes into smaller molecules, purifying and decolorizing the dyes, with a degradation rate constant K*100 as high as 4.8 min. -1 . Attached Figure Description

[0017] Figure 1 The X-ray powder diffraction pattern of BC prepared in Example 1 is shown.

[0018] Figure 2 The image shows the X-ray powder diffraction pattern of the TiO2-LaOCl@BC composite photocatalyst prepared in Example 1.

[0019] Figure 3 The image shows a scanning electron microscope (SEM) image of the TiO2-LaOCl@BC composite photocatalyst prepared in Example 1, where a and b represent low and high magnification, respectively.

[0020] Figure 4 The image shows the X-ray powder diffraction pattern of the activated carbon used in Example 3.

[0021] Figure 5 The image shows the X-ray powder diffraction pattern of the TiO2-LaOCl@C composite photocatalyst prepared in Example 3.

[0022] Figure 6 This is a graph showing the percentage degradation of organic dyes by various catalysts in Example 4 under visible light catalysis.

[0023] Figure 7 This is a cyclic degradation diagram of methylene blue catalytic degradation under visible light using TiO2-LaOCl@BC as a catalyst in Example 5. Detailed Implementation

[0024] The following detailed description, in conjunction with embodiments and accompanying drawings, provides a titanium-lanthanum composite banana peel carbon-based photocatalyst proposed in this invention, its preparation method, and its application.

[0025] Example 1

[0026] Preparation of the composite photocatalyst TiO2-LaOCl@BC:

[0027] ① Dry the banana peels to remove moisture, then grind them in a grinder. Under a nitrogen atmosphere, place the banana peel powder in a heating furnace, raise the temperature to 800℃ at a rate of 5℃ / min, and hold for 2 hours. After the reaction is complete, remove the product to obtain banana peel carbon BC.

[0028] like Figure 1 As shown, in addition to amorphous carbon, BC contains a certain amount of potassium chloride. The position of the XRD diffraction peak corresponds exactly to the PDF#01-0786 card, which can explain the source of Cl element in the subsequent preparation of TiO2-LaOCl@BC, demonstrating the natural advantages of BC.

[0029] ② Take 2.4g BC, 0.147g lanthanum nitrate, and 0.054g titanium dioxide, grind and mix them evenly, then transfer the mixed powder to a heating furnace, heat to 500℃ at 5℃ / min and hold for 1h. After the reaction is complete, remove the product to obtain TiO2-LaOCl@BC.

[0030] like Figure 2 As shown, the diffraction peak positions of TiO2 and LaOCl correspond perfectly to PDF#21-1276 and PDF#88-0064, respectively, indicating that the composite of TiO2 and LaOCl was successfully prepared in this invention. Figure 3 As can be seen from a and b, TiO2 and LaOCl are uniformly dispersed on the surface of BC. LaOCl is coated on the surface of BC through a chemical reaction, and TiO2 and LaOCl@BC are uniformly mixed, indicating that the structure of the present invention is BC coated with TiO2 and LaOCl, and the three form a cross-uniformly mixed whole.

[0031] Example 2

[0032] Preparation of the composite photocatalyst TiO2-LaOCl@BC:

[0033] ① Dry the banana peels to remove moisture, then grind them in a grinder. Under an Ar atmosphere, place the banana peel powder in a heating furnace, heat it to 500℃ at a rate of 10℃ / min, and hold it at that temperature for 10 hours. After the reaction is complete, remove the product to obtain banana peel carbon BC.

[0034] ② Take 2.4g BC, 1.47g lanthanum nitrate, and 0.54g titanium dioxide, grind and mix them evenly, then transfer the mixed powder to a heating furnace, heat it to 800℃ at 20℃ / min and hold it at that temperature for 0.3h. After the reaction is complete, take out the product to obtain TiO2-LaOCl@BC.

[0035] Example 3

[0036] Preparation of the composite photocatalyst TiO2-LaOCl@C:

[0037] Take 2.4g of commercial activated carbon, 0.147g of lanthanum nitrate, 0.054g of titanium dioxide, and 0.025g of potassium chloride, grind and mix them evenly, then transfer the mixed powder to a heating furnace, heat it to 500℃ at a rate of 5℃ / min, and hold it at that temperature for 1 hour. After the reaction is complete, remove the product to obtain TiO2-LaOCl@C.

[0038] like Figure 4 As shown, commercial activated carbon is amorphous carbon, similar to banana peel, but because it is commercial activated carbon, it contains some trace impurities.

[0039] like Figure 5 As shown, the positions of the XRD diffraction peaks are consistent with the standard PDF cards PDF#21-1276 and PDF#88-0064 for TiO2 and LaOCl, indicating the successful synthesis of TiO2-LaOCl@C. Although potassium chloride was added in the same proportion to simulate banana peel carbon, the diffraction peaks of LaOCl are still very weak. The comparison shows the natural advantages of banana peel carbon.

[0040] Example 4

[0041] Composite photocatalyst TiO2-LaOCl@BC photocatalytic degradation of organic dyes:

[0042] A 300W xenon lamp equipped with a 400nm filter was used as the light source. An appropriate amount of catalyst powder was placed in a 250mL beaker containing 100mL of organic dye and stirred with a magnetic stirrer. Specific reaction conditions are shown in Table 1. The system was first shielded from light and allowed to adsorb in the dark for 30 minutes, followed by photocatalysis with the xenon lamp for 2 hours. During this period, the solution was sampled every 15 minutes, and the concentration was measured using a UV spectrophotometer.

[0043] Table 1. Specific experimental parameters and degradation rate constant K for visible light catalytic degradation of organic dyes using various catalysts.

[0044]

[0045]

[0046] Combination Figure 6As shown, the performance of TiO2-LaOCl@BC is far superior to that of random combinations of other raw materials. Table 1 further illustrates this: TiO2-LaOCl@BC (No. 4, prepared in Example 1) has a K value as high as 4.8, which is 3.2 times that of modified activated carbon (No. 5, prepared in Example 3), and more than 4 times higher than that of commercial titanium dioxide (No. 2) and g-C3N4 (No. 3). Therefore, the advantages of banana peel carbon are clearly evident.

[0047] Example 5

[0048] Photocatalytic degradation experiment of organic dyes by composite photocatalyst TiO2-LaOCl@BC:

[0049] The TiO2-LaOCl@BC composite photocatalyst after photodegradation in Example 4 was collected, and 20 mg was placed in a 250 mL beaker. 100 mL of a 10 mg / L methylene blue solution was added, and a 300 W xenon lamp equipped with a 400 nm filter was used as the light source. The system was first shielded from light and allowed to adsorb in the dark for 30 min, followed by photocatalysis with the xenon lamp for 2 h. During this period, the solution was sampled every 15 min, and the concentration was measured using a UV spectrophotometer. This process was repeated 5 times to obtain the cyclic degradation performance of the TiO2-LaOCl@BC composite photocatalyst.

[0050] like Figure 7 As shown, TiO2-LaOCl@BC exhibits excellent cycling performance, reaching 90% after five cycles. The first and second cycles show a significant decrease, while subsequent cycles show a relatively stable performance, demonstrating the high stability of the TiO2-LaOCl@BC material.

[0051] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A titanium-lanthanum composite banana peel carbon-based photocatalyst TiO2-LaOCl@BC, characterized in that, BC is carbon produced by carbonizing banana peels. In TiO2-LaOCl@BC, TiO2 and LaOCl are uniformly dispersed on the surface of BC. LaOCl is coated on the surface of BC through a chemical reaction. TiO2 and LaOCl@BC are mixed evenly.

2. A method for preparing the titanium-lanthanum composite banana peel carbon-based photocatalyst TiO2-LaOCl@BC as described in claim 1, characterized in that, The TiO2-LaOCl@BC photocatalyst is generated by reacting banana peel carbon (BC), lanthanum nitrate, and titanium dioxide under heating conditions, specifically including the following steps: ① After drying the banana peel, crush it with a pulverizer, then place it in a heating furnace. Under the protection of inert gas, heat the temperature in the heating furnace to 500-800℃ at a heating rate of 5-20℃ / min, and hold it at this temperature for 0.1-10 hours for carbonization. Then, perform acid soaking, filtration, water washing, and drying to obtain banana peel carbon BC. ② Mix banana peel carbon BC, lanthanum nitrate and titanium dioxide in a molar ratio of 600:1~20:1~20, and then transfer the mixed powder to a heating furnace; ③ Under the protection of inert gas, the heating furnace is heated to 500-800℃ at a heating rate of 5-20℃ / min and held for 0.1-10h; ④ After the heating reaction is complete, the product is removed to obtain the titanium-lanthanum composite banana peel carbon-based photocatalyst TiO2-LaOCl@BC.

3. The method as described in claim 2, characterized in that, The drying process described in step ① includes atmospheric pressure drying, freeze drying, or vacuum drying.

4. The method as described in claim 2, characterized in that, The uniform mixing methods described in step ② include mechanical ball milling, mechanical stirring, and manual grinding.

5. The method as described in claim 2, characterized in that, The inert gas mentioned in steps ① and ③ is one or more of nitrogen, argon, and helium.

6. The application of the titanium-lanthanum composite banana peel carbon-based photocatalyst TiO2-LaOCl@BC as described in claim 1 in the photocatalytic degradation of organic dyes.

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