Application of nano-bismuth ferrite in tribocatalytic degradation of high-concentration methyl orange dye

Abstract

The present invention relates to the technical field of tribocatalytic degradation of pollutants, specifically the use of nano-bismuth ferrite in the tribocatalytic degradation of high-concentration methyl orange dye. The specific catalytic method includes the following steps: S1, pouring a methyl orange solution into a container, and adding bismuth ferrite nanopowder to the methyl orange solution; S2, adding a friction turntable to the container, with the bottom surface of the friction turntable in contact with the bottom surface of the container; S3, rotating the friction turntable by external force, so that the bismuth ferrite nanopowder completes the catalytic degradation of the methyl orange. The present invention degrades methyl orange through tribocatalysis, greatly improving degradation efficiency and promoting further exploration of tribocatalysts.

Description

Technical Field

[0001] The invention relates to the technical field of tribocatalytic degradation of pollutants, in particular to application of nano-bismuth ferrite in tribocatalytic degradation of high-concentration methyl orange dye. Background Art

[0002] The international community generally recognizes that water pollution is a serious problem. The discharge of organic dyes into wastewater from industries such as textiles, leather, food, and chemicals poses a serious threat to the health of aquatic bodies. Organic dyes are widely used as colorants in the textile, cosmetics, leather, papermaking, plastics, printing, rubber, and pharmaceutical industries, and their use has caused serious water pollution. Dyes affect the human central nervous system, liver, kidneys, skin, enzyme systems, chromosomes, and reproductive systems. Among them, methyl orange (MO) is one of the most widely used harmful anionic azo dyes. Due to its complex aromatic composition and diverse biological properties, it has become a highly persistent and difficult-to-treat xenobiotic, posing a significant burden on humans.

[0003] Existing catalytic degradation methods include adsorption, electrocatalysis, and photocatalysis. Each of these technologies has its own advantages and disadvantages. For example, photocatalysis, as a mainstream catalytic method, plays an irreplaceable role in the degradation of toxic substances, dye conversion, and energy conversion. However, photocatalysis has low light energy utilization efficiency, a strong dependence on ultraviolet light, a high electron-hole recombination rate, and once the reaction begins, subsequent reactions are difficult to control. To address the growing environmental crisis, research is turning its attention to mechanical energy in the environment.

[0004] It is well known that mechanical energy can be easily absorbed by materials through friction and converted into other forms of energy, including chemical energy, heat energy and light energy. In recent years, the concept of converting mechanical energy into chemical energy through friction, namely tribocatalysis, has attracted increasing attention as an emerging energy collection and conversion method. Bismuth ferrite is a narrow bandgap semiconductor material with a bandgap width of 2.08eV. The energy generated during friction promotes the e - and h + The free radical capture experiment showed that h + It is the main active substance in the friction catalytic process and is beneficial to the catalytic decomposition of methyl orange. Summary of the Invention

[0005] The purpose of the present invention is to provide an application of nano-bismuth ferrite in the friction-catalytic degradation of high-concentration methyl orange dye, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] Application of nano-bismuth ferrite in tribocatalytic degradation of high-concentration methyl orange dye.

[0008] Furthermore, the application method comprises the following steps:

[0009] S1. Pour methyl orange solution into a container, and add bismuth ferrite nanopowder into the methyl orange solution;

[0010] S2. Place the friction disc into the container, with the bottom surface of the friction disc in contact with the bottom surface of the container;

[0011] S3. The friction turntable is rotated by external force, and the bismuth ferrite nanopowder completes the catalytic degradation of methyl orange.

[0012] Furthermore, the concentration of the methyl orange solution is 10-40 mg / L.

[0013] Furthermore, the mass ratio of the bismuth ferrite nanopowder to the methyl orange solution is 1:(900-1100).

[0014] Furthermore, the particle size of the bismuth ferrite nanopowder is 100-200 nm.

[0015] Furthermore, a groove is provided on the bottom surface of the friction turntable.

[0016] Furthermore, the rotation speed of the friction disc is 350-500 rpm.

[0017] Furthermore, the temperature for friction catalytic degradation of methyl orange by the bismuth ferrite nanopowder is 15-30°C.

[0018] Furthermore, the bismuth ferrite nanopowder is prepared by a sol-gel method using ferric nitrate as an iron source and bismuth nitrate as a bismuth source.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This study used bismuth ferrite nanopowder prepared using a sol-gel method and applied it to the tribochemical degradation of methyl orange. Compared to titanium dioxide nanopowder (P25), the catalytic degradation of methyl orange dye at concentrations of 10 mg / L, 20 mg / L, 30 mg / L, and 40 mg / L showed that bismuth ferrite nanopowder (BFO) completely degraded a 40 mg / L methyl orange solution through friction in just 210 minutes, while TiO2 (P25) required 720 minutes. This study demonstrates that perovskite-structured multiferroic nanoparticles are an economical and environmentally friendly tribocatalyst, promoting further exploration of tribocatalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the XRD pattern of BFO in the present invention;

[0022] Figure 2is the SEM image of BFO in the present invention;

[0023] Figure 3 is the SEM image of P25 in the present invention;

[0024] Figure 4 Schematic diagram of the tribocatalytic degradation of 40 mg / L methyl orange by BFO in the present invention;

[0025] Figure 5 Schematic diagram of the friction catalytic degradation of 40 mg / L methyl orange by P25 in the present invention

[0026] Figure 6 This is a graph showing the degradation rate of BFO to methyl orange at different concentrations in the present invention;

[0027] Figure 7 This is a graph showing the degradation rate of P25 to methyl orange at different concentrations;

[0028] Figure 8 Schematic diagram of the degradation of 40 mg / L methyl orange by a single BFO magnet in the present invention;

[0029] Figure 9 This is a diagram of the BFO active species capture experiment in the present invention;

[0030] Figure 10 This is a diagram of the BFO friction catalysis mechanism of the present invention;

[0031] Figure 11 A schematic diagram of the friction turntable used in the present invention;

[0032] Figure 12 The UV diffuse reflectance images of BFO and P25 in the present invention;

[0033] Figure 13 Band gap diagram of BFO and P25 in the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] See also Figures 1 to 13 , the present invention provides:

[0036] Application of nano-bismuth ferrite in friction catalytic degradation of high-concentration methyl orange dye,

[0037] (1) Preparation of bismuth ferrite nanopowder

[0038] The preparation of bismuth ferrite nanopowder adopts the following steps:

[0039] S101. Weigh out 20 ml of ethylene glycol solution using a measuring cylinder, then weigh out 0.02 mol (8.2112 g) of Fe(NO3)3·9H2O, mix the two, pour them into a beaker, and stir them on a magnetic heating stirrer at 50°C for 1.5 hours; then weigh out 60 ml of ethylene glycol solution using a measuring cylinder and 0.021 mol of Bi(NO3)3·5H2O (10.4853 g, 5% excess is required because bismuth is easily volatile when heated) using a balance, mix the two, pour them into a beaker, and stir them on a magnetic heating stirrer at 50°C for 1.5 hours to fully dissolve them; finally, mix the solutions in the two beakers, stir them continuously on a magnetic heating stirrer at 60°C for 3 hours until fully mixed, and then let them stand for a period of time to form a deep red sol;

[0040] S102. The deep red sol prepared in step S101 is placed in a drying oven set at 100°C for 96 hours. During the drying process, a thin film begins to appear on the sample after about 4 hours. After 72 hours, all the samples are dried and aged into block-like xerogels. The mortar and pestle are then cleaned and the dried sample is placed in it and slowly ground.

[0041] S103, the powdered sample prepared in S102 is placed in a porcelain boat, and the excess sample powder is marked and sealed for later use. The porcelain boat is then placed in a tubular muffle furnace and programmed to heat from room temperature to 120°C in 30 minutes and hold for 40 minutes, then to 300°C in 30 minutes and hold for 40 minutes, then to 600°C in 30 minutes and hold for 3 hours, and finally to terminate the heating and allow the sample to cool naturally. After annealing, the sample turns khaki in color.

[0042] S104, washing the khaki powder obtained in step S103 with 10% dilute nitric acid, then washing it again with deionized water, and drying it in a drying oven at 100° C. for about three hours to obtain the desired bismuth ferrite nanopowder.

[0043] (2) Analysis of samples and characterization tests

[0044] The XRD spectra of the samples used in the experiment are shown in Figure 1As shown in Figure 2, the card number (XRD standard card library number) of the bismuth ferrite nanopowder (BFO) prepared by the sol-gel method is highly consistent with the perovskite structure, indicating that the sol-gel method is a better method for preparing single-phase BFO nanopowders. The titanium dioxide nanopowder (P25) used in this experiment is commercially available P25. The XRD results show that P25 is anatase phase (PD#21-1272) TiO2 and rutile phase (PDF#21-2176) TiO2, which is consistent with the known composition and structure of P25. The electron microscope images of the two materials are shown in Figure 2. Figure 2 (BFO) and Figure 3 As shown in (P25), the particle size of P25 is about 50 nm, and the particle size distribution of BFO is between 100-200 nm.

[0045] (3) Experiment on friction catalytic degradation of methyl orange

[0046] 0.3 g of BFO nanopowder and P25 nanopowder were added to 30 mL of methyl orange solution (10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L), and the degradation rate curves of BFO nanopowder and P25 nanopowder for different concentrations of methyl orange were shown as follows: Figure 6 and Figure 7 As shown, the methyl orange solution is contained in a glass beaker (420 mm × 600 mm), and a Teflon turntable (a cross-groove friction turntable specially designed by Li et al. for monitoring degradation details) is placed in the suspension. The turntable contacts the bottom of the glass beaker to generate friction mechanical energy. The turntable structure is as shown in FIG. Figure 11 As shown), the beaker was sealed and placed in the dark at 20°C and magnetically stirred at 400 rpm; in order to characterize the fading, 3 ml of the suspension was sampled at fixed intervals; the suspension was immediately centrifuged after collection and tested by UV-visible spectrophotometry; the results were shown in FIG. Figure 4 、 Figure 5 It can be found (for the catalytic degradation experiment of 40 mg / L methyl orange solution), compared with P25 nanopowder, BFO nanopowder prepared by sol-gel method shows excellent tribocatalytic degradation performance for the difficult-to-degrade methyl orange organic dye.

[0047] (IV) Comparative experiment to verify that methyl orange degradation is not due to nanomaterial adsorption

[0048] In order to demonstrate the tribocatalytic effect of BFO nanopowder, a BFO single-magnet degradation experiment was conducted (in this experiment, the single-magnet did not contact the bottom of the glass beaker and no frictional mechanical energy was generated) to clarify that physical adsorption does not play a major role in the degradation of methyl orange dye. By using a magnetic stirring rod with a rubber gasket to eliminate the tribocatalytic effect, regular sampling was performed and UV-visible spectrophotometry was performed. The results are shown in Figure 2. Figure 8As shown, the peak position of methyl orange also decreases with the passage of time, but the degradation time is much longer than that of friction catalysis. When degrading 40 mg / L methyl orange dye, the peak position is still very high after 8 hours, and the adsorption amount is only 40%. Using the friction catalytic turntable, a high concentration of 40 mg / L methyl orange dye is almost completely degraded within 210 minutes, fully demonstrating the excellent performance of friction catalysis and proving that BFO nanopowder can efficiently complete the degradation of methyl orange through friction catalysis.

[0049] (V) Active species capture experiment of bismuth ferrite nanopowder

[0050] Before the experiment, 0.03 mmol BQ, 0.03 mmol EDTA-2Na, 0.03 mmol TBA, and 0.03 mmol AgNO3 were introduced into a beaker containing 300 mg BFO nanoparticles and 30 mL of a methyl orange solution with a concentration of 40 mg / L. These scavengers can effectively neutralize the O 2- Free radicals, h + , OH radicals and e - Subsequently, the same conditions as those used in the methyl orange dye degradation experiment were used to evaluate the catalytic effect of friction on dye degradation. Figure 9 As shown, from Figure 9 It can be seen that the active substance of BFO tribocatalytic degradation of methyl orange is h + At the same time, the active role of oxygen ions cannot be ignored. The experimental study on the capture of active substances by P25 showed that both holes and hydroxide ions play a role in the tribocatalytic degradation of methyl orange dye. Based on this, the following conclusions were drawn: Figure 10 The diagram shows the tribocatalytic mechanism of BFO nanopowder.

[0051] Compared with various catalytic materials, bismuth ferrite materials have a narrower band gap structure such as Figure 12-13 ( Figure 12 UV diffuse reflectance images of BFO and P25. Figure 13 (Band gap diagram of BFO and P25) It can quickly degrade high concentration of methyl orange dye under friction catalysis conditions. Compared with P25 nanopowder, at concentrations of 10 mg / L, 20 mg / L, 30 mg / L and 40 mg / L, the speed of BFO nanopowder to completely degrade methyl orange dye is 7.5 times, 9.6 times, 3.375 times and 3.429 times that of P25 nanopowder, respectively, indicating that it is a high-performance catalyst for degrading methyl orange.

[0052] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. Application of nano-bismuth ferrite in tribo-catalytic degradation of methyl orange dye; The bismuth ferrite nanopowder is prepared by a sol-gel method using ferric nitrate as an iron source and bismuth nitrate as a bismuth source. The bismuth ferrite powder has a perovskite structure; The concentration of the methyl orange solution is 10-40 mg / L.

2. The use of nano-bismuth ferrite according to claim 1 in friction catalysis to reduce methyl orange dye, characterized in that: The application method includes the following steps: S1. Pour methyl orange solution into a container, and add bismuth ferrite nanopowder into the methyl orange solution; S2. Place the friction disc into the container, with the bottom surface of the friction disc in contact with the bottom surface of the container; S3. The friction turntable is rotated by external force, and the bismuth ferrite nanopowder completes the catalytic degradation of methyl orange.

3. The use of nano-bismuth ferrite in tribocatalytic degradation of methyl orange dye according to claim 1, characterized in that: The mass ratio of the bismuth ferrite nanopowder to the methyl orange solution is 1:(900-1100).

4. The use of nano-bismuth ferrite in tribocatalytic degradation of methyl orange dye according to claim 1, characterized in that: The particle size of the bismuth ferrite nanopowder is 100-200 nm.

5. The use of nano-bismuth ferrite in tribocatalytic degradation of methyl orange dye according to claim 1, characterized in that: The bottom surface of the friction rotating disk is provided with grooves.

6. The use of nano-bismuth ferrite in tribocatalytic degradation of methyl orange dye according to claim 1, characterized in that: The rotation speed of the friction disc is 350-500 rpm.

7. The use of nano-bismuth ferrite in tribocatalytic degradation of methyl orange dye according to claim 1, characterized in that: The temperature for friction catalytic degradation of methyl orange by the bismuth ferrite nanopowder is 15-30°C.

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