Ultrasonic enhanced red mud-based catalytic material degradation method and application

Abstract

The invention is applicable to the technical field of catalytic materials and degradation, and provides an ultrasonic enhanced red mud-based catalytic material degradation method and application, the method comprises the following steps: step 1, crushing red mud, drying, grinding the dried sample by a ball mill, and sieving to obtain a sample A; 2, biomass is dried and ground into powder, and an undersize sample B is obtained after sieving; 3, the sample A and the sample B are subjected to ball-milling mixing according to a certain proportion, the mixed sample is placed in a tubular furnace to be subjected to high-temperature roasting, and the red mud-based catalytic material is obtained after cooling; 4, the red mud-based catalytic material is used for degrading pollutants in sewage under visible light, and the degradation process is promoted through external ultrasound. According to the method, recycling and reusing are facilitated, efficient secondary utilization of the waste red mud and agricultural and forestry waste is achieved, and the environmental protection target of treating waste with waste is truly achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic materials and degradation, and in particular relates to an ultrasonically enhanced red mud-based catalytic material degradation method and application. Background Art

[0002] Advanced oxidation processes (AOPs) have attracted much attention due to their ability to effectively remove organic pollutants, among which the role of reactive oxygen species (ROSs) is particularly significant. Photocatalysis (PC), as a type of AOP, is considered a potential solution due to its excellent stability and ability to generate highly active free radicals with strong oxidizing properties. However, the effectiveness of photocatalysts is often limited by problems such as surface aggregation, precipitation, and accumulation of pollutants. To this end, combining acoustic wave technology with photocatalysis, namely sonophotocatalysis (SPC), has been proposed as an effective strategy to solve the above problems. In SPC, cavitation helps to continuously clean the catalyst surface and reduce pollutant accumulation; at the same time, the introduction of ultrasound (US) can further inhibit the recombination of photogenerated carriers and increase the yield of ROSs, thereby enhancing the overall reaction efficiency.

[0003] Singlet oxygen ( 1 O2) as a non-radical ROSs, has attracted attention due to its high tolerance to environmental changes and its efficient degradation ability for specific pollutants. 1 O2 can be generated through three mechanisms: energy transfer, Although the energy transfer pathway is difficult in the photocatalytic process, the latter two mechanisms can be effectively promoted by improving the efficiency of photoinduced carrier separation, that is, increasing the generation of electrons and holes. This goal can be achieved by constructing heterostructures.

[0004] Red mud (RM), a byproduct of alumina production, is rich in silicon dioxide (SiO2), aluminum oxide (Al2O3) and iron oxide (Fe2O3). RM can be converted into an efficient AOPs catalyst, FeAl2O4, by heat treatment under a reducing atmosphere. In addition, agricultural and forestry wastes such as reeds, rice husks and coffee grounds are ideal raw materials for preparing biochar because they contain a high proportion of carbon and a low content of inorganic matter. During the co-pyrolysis of these agricultural and forestry wastes (RS) and RM, the reducing gases (such as CH4, CO and H2) released by RS can promote the conversion of Fe2O3 / Al2O3 in RM under reducing conditions to form biochar containing FeAl2O4 / Fe3O4 phases. This method not only provides a new idea for the treatment of various solid wastes, but also opens up a new way to prepare efficient photocatalysts at low cost.

[0005] Therefore, in view of the above situation, there is an urgent need to develop an ultrasound-enhanced red mud-based catalytic material degradation method to overcome the shortcomings in current practical applications. Summary of the invention

[0006] The purpose of the present invention is to provide an ultrasound-enhanced red mud-based catalytic material degradation method and application, aiming to solve the problems mentioned in the above background technology.

[0007] The present invention is achieved by a method for ultrasonically enhancing the degradation of red mud-based catalytic materials, comprising the following steps:

[0008] Step 1: crush the red mud and dry it, and then grind and sieve the dried sample through a ball mill to obtain sample A;

[0009] Step 2: drying the biomass, grinding it into powder, and sieving it to obtain a sieve sample B;

[0010] Step 3: ball-milling sample A and sample B in a certain proportion, calcining the mixed sample at high temperature in a tube furnace, and obtaining a red mud-based catalytic material after cooling;

[0011] Step 4: The red mud-based catalytic material is used for the degradation of pollutants in wastewater under visible light, and external ultrasound is used to promote the degradation process.

[0012] In a further technical solution, in steps 1 and 2, the ball milling speed is 350-400 rpm / min, the ball milling time is 60-80 min, and the sieve hole diameter is 75 microns. The biomass is generally agricultural and forestry waste, including rice husks, straw, reeds, coffee grounds, etc.

[0013] A further technical solution is that in step 3, the mixing ratio of sample A and sample B is A:B=40%-60%, the ball milling mixing time is 30-40min, the rotation speed is 250-300rpm / min, the tubular furnace roasting temperature is 1000-1300℃, the heating rate is 5℃ / min, the insulation time is 30-40min, and high-purity nitrogen is used for protection during the entire roasting process, and the nitrogen flow rate is 0.5L / min.

[0014] According to a further technical solution, in step 4, the sewage is generally industrial sewage or domestic sewage, such as sewage containing new pollutants such as antibiotics and endocrine disruptors, and the sewage turbidity is generally <10NTU.

[0015] A further technical solution is that in step 4, the amount of the red mud-based catalytic material added is generally determined according to the COD (mg / L) of the sewage, and is added at 3-6‰ of the COD content. The ultrasound begins 10-15 minutes before the addition of the red mud-based catalytic material, and the ultrasound frequency is 40-80kHz. The ultrasound process is carried out under visible light, such as sunlight irradiation or simulated sunlight irradiation, the power of the simulated irradiation device is generally 300W, and continuous stirring or aeration is performed during the degradation process.

[0016] Another object of the present invention is to apply the ultrasound-enhanced red mud-based catalytic material degradation method to the degradation of pollutants in industrial wastewater or domestic sewage.

[0017] The ultrasonic enhanced red mud-based catalytic material degradation method provided by the present invention has the following beneficial effects:

[0018] 1) The composite catalyst of the present invention turns red mud and agricultural and forestry solid waste into treasure, and solves the problem of solid waste pollution to the environment while efficiently treating industrial sewage, truly achieving the purpose of "treating waste with waste" and realizing the utilization of solid waste resources;

[0019] 2) The composite material of the present invention has certain magnetism and large particles, and can be recovered by magnetic separation or filtration, and is suitable for a variety of process occasions;

[0020] 3) The present invention cooperates in materials and processes to solve the non-radical pathway that cannot be achieved by photocatalysis or ultrasound of a single material, and can greatly promote the degradation process dominated by singlet oxygen, thereby improving the degradation efficiency;

[0021] 4) The composite material of the present invention can be recycled, thus saving processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A scanning electron microscope image of a red mud-based catalytic material used in the ultrasonically enhanced red mud-based catalytic material degradation method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0025] Example 1

[0026] like Figure 1 As shown, an ultrasonic enhanced red mud-based catalytic material degradation method provided by one embodiment of the present invention comprises the following steps:

[0027] 1. Put the red mud and rice husk into a drying box and dry them at 80°C for 24 hours. After drying, put them into a ball mill and grind them at 400r / min for 60 minutes. Sieve the ground materials with a 200-mesh standard test sieve to obtain samples A and B.

[0028] 2. Samples A and B were mixed in a ratio of A:B = 50%, and mixed in a ball mill at a speed of 250 r / min for 30 min. 20 g of the mixed sample was placed in a laboratory tube furnace, and nitrogen was used as the protective gas. The nitrogen flow rate was set to 3 L / min. The air in the tube furnace was pre-extracted before heating, and then nitrogen was continuously introduced. The temperature was raised to 1100°C at a heating rate of 5°C / min and kept warm for 30 min to obtain a red mud-based catalytic material.

[0029] 3. Prepare 500 mL of 20 mg / L tetracycline hydrochloride solution, add catalytic material to the tetracycline hydrochloride solution in an amount of 0.6 g / L, use a laboratory light source to simulate natural light irradiation, the power is 300 W, place it in a constant temperature stirrer, stir and degrade at room temperature, starting from the beginning of stirring, take out about 3.0 mL of solution every 1 min, and filter it with a 0.22 micron filter membrane, and measure the absorbance of the filtrate at the maximum absorption wavelength (357 nm) with a UV-visible spectrophotometer to calculate the concentration of tetracycline hydrochloride.

[0030] 4. The results showed that after 5 minutes of degradation, the degradation rate of tetracycline hydrochloride in the tested sample was 60.5%.

[0031] Comparative Example 1

[0032] 1. Put the red mud and rice husk into a drying box and dry them at 80°C for 24 hours. After drying, put them into a ball mill and grind them at 400r / min for 60 minutes. Sieve the ground materials with a 200-mesh standard test sieve to obtain samples A and B.

[0033] 2. Samples A and B were mixed in a ratio of A:B = 50%, and mixed in a ball mill at a rotation speed of 250 r / min for 30 min. 20 g of the mixed sample was placed in a laboratory tube furnace, and nitrogen was used as the protective gas. The nitrogen flow rate was set to 3 L / min. The air in the tube furnace was pre-extracted before heating, and then nitrogen was continuously introduced. The temperature was raised to 900°C at a heating rate of 5°C / min and kept warm for 30 min to obtain a red mud-based catalytic material.

[0034] 3. Prepare 500 mL of 20 mg / L tetracycline hydrochloride solution, add catalytic material to the tetracycline hydrochloride solution in an amount of 0.6 g / L, use a laboratory light source to simulate natural light irradiation, the power is 300 W, place it in a constant temperature stirrer, stir and degrade at room temperature, starting from the beginning of stirring, take out about 4.0 mL of solution every 10 minutes, and filter it with a 0.22 micron filter membrane, and measure the absorbance of the filtrate with a UV-visible spectrophotometer at the maximum absorption wavelength (357 nm) to calculate the concentration of tetracycline hydrochloride.

[0035] 4. The results showed that after 5 minutes of degradation, the degradation rate of tetracycline hydrochloride in the tested sample was 18.9%.

[0036] Comparative Example 2

[0037] 1. Put the red mud and rice husk into a drying box and dry them at 80°C for 24 hours. After drying, put them into a ball mill and grind them at 400r / min for 60 minutes. Sieve the ground materials with a 200-mesh standard test sieve to obtain samples A and B.

[0038] 2. Samples A and B were mixed in a ratio of A:B = 30%, and mixed in a ball mill at a speed of 250 r / min for 30 min. 20 g of the mixed sample was placed in a laboratory tube furnace, and nitrogen was used as the protective gas. The nitrogen flow rate was set to 3 L / min. The air in the tube furnace was pre-extracted before heating, and then nitrogen was continuously introduced. The temperature was raised to 1100°C at a heating rate of 5°C / min and kept warm for 30 min to obtain a red mud-based catalytic material.

[0039] 3. Prepare 500 mL of 20 mg / L tetracycline hydrochloride solution, add catalytic material to the tetracycline hydrochloride solution in an amount of 0.6 g / L, use a laboratory light source to simulate natural light irradiation, the power is 300 W, place it in a constant temperature stirrer, stir and degrade at room temperature, starting from the beginning of stirring, take out about 4.0 mL of solution every 10 minutes, and filter it with a 0.22 micron filter membrane, and measure the absorbance of the filtrate with a UV-visible spectrophotometer at the maximum absorption wavelength (357 nm) to calculate the concentration of tetracycline hydrochloride.

[0040] 4. The results showed that after 5 minutes of degradation, the degradation rate of tetracycline hydrochloride in the tested sample was 35.6%.

[0041] Comparative Example 3

[0042] 1. Put the red mud and rice husk into a drying box and dry them at 80°C for 24 hours. After drying, put them into a ball mill and grind them at 400r / min for 60 minutes. Sieve the ground materials with a 200-mesh standard test sieve to obtain samples A and B.

[0043] 2. Samples A and B were mixed in a ratio of A:B = 50%, and mixed in a ball mill at a speed of 250 r / min for 30 min. 20 g of the mixed sample was placed in a laboratory tube furnace, and nitrogen was used as the protective gas. The nitrogen flow rate was set to 3 L / min. The air in the tube furnace was pre-extracted before heating, and then nitrogen was continuously introduced. The temperature was raised to 1100°C at a heating rate of 5°C / min and kept warm for 30 min to obtain a red mud-based catalytic material.

[0044] 3. Prepare 500mL of 20mg / L tetracycline hydrochloride solution, add catalytic material to the tetracycline hydrochloride solution, the amount added is 0.6g / L, use laboratory light source to simulate natural light irradiation, the power is 300W, and use laboratory ultrasonic device to ultrasonically treat at the same time, the ultrasonic power is 40kHz. The reaction process is carried out in a constant temperature stirrer, stirring and degrading at room temperature. From the beginning of stirring, take out about 4.0mL of solution every 10min, and filter with 0.22 micron filter membrane, and measure the absorbance of the filtrate at the maximum absorption wavelength (357nm) with UV-visible spectrophotometer to calculate the concentration of tetracycline hydrochloride.

[0045] 4. The results showed that after 5 minutes of degradation, the degradation rate of tetracycline hydrochloride in the tested sample was 98.1%.

[0046] The above embodiment of the present invention provides an ultrasound-enhanced red mud-based catalytic material degradation method, which has the following advantages:

[0047] 1) The composite catalyst of the present invention turns red mud and agricultural and forestry solid waste into treasure, and solves the problem of solid waste pollution to the environment while efficiently treating industrial sewage, truly achieving the purpose of "treating waste with waste" and realizing the utilization of solid waste resources;

[0048] 2) The composite material of the present invention has certain magnetism and large particles, and can be recovered by magnetic separation or filtration, and is suitable for a variety of process occasions;

[0049] 3) The present invention cooperates in materials and processes to solve the non-radical pathway that cannot be achieved by photocatalysis or ultrasound of a single material, and can greatly promote the degradation process dominated by singlet oxygen, thereby improving the degradation efficiency;

[0050] 4) The composite material of the present invention can be recycled, thus saving processing costs.

[0051] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for ultrasonically enhancing the degradation of red mud-based catalytic materials, characterized in that: The following steps are involved: Step 1: crush the red mud and dry it, and then grind and sieve the dried sample through a ball mill to obtain sample A; Step 2: drying the biomass, grinding it into powder, and sieving it to obtain a sieve sample B; Step 3: ball-milling sample A and sample B in a certain proportion, calcining the mixed sample at high temperature in a tube furnace, and obtaining a red mud-based catalytic material after cooling; Step 4: The red mud-based catalytic material is used for the degradation of pollutants in wastewater under visible light, and external ultrasound is used to promote the degradation process.

2. The method for ultrasonically enhanced degradation of red mud-based catalytic materials according to claim 1, characterized in that: In steps 1 and 2, the ball milling speed is 350-400 rpm / min, the ball milling time is 60-80 min, and the mesh diameter is 75 microns.

3. The method for ultrasonically enhanced degradation of red mud-based catalytic materials according to claim 1, characterized in that: In step 2, the biomass is agricultural and forestry waste.

4. The method for ultrasonically enhanced red mud-based catalytic material degradation according to claim 1, characterized in that: In step 3, the mixing ratio of sample A and sample B is A:B=40%-60%, the ball milling mixing time is 30-40min, and the rotation speed is 250-300rpm / min; The calcination temperature in the tubular furnace is 1000-1300°C, the heating rate is 5°C / min, the holding time is 30-40min, and high-purity nitrogen is used for protection throughout the calcination process at a nitrogen flow rate of 0.5L / min.

5. The method for ultrasonically enhancing the degradation of red mud-based catalytic materials according to any one of claims 1 to 4, characterized in that: In step 4, the sewage is industrial sewage or domestic sewage, and the sewage turbidity is less than 10NTU.

6. The method for ultrasonically enhancing red mud-based catalytic material degradation according to claim 5, characterized in that: In step 4, the red mud-based catalytic material is added in an amount of 3-6‰ of the COD content of the sewage.

7. The method for ultrasonically enhanced degradation of red mud-based catalytic materials according to claim 6, characterized in that: In step 4, the ultrasound starts 10-15 minutes before the addition of the red mud-based catalytic material, the ultrasound frequency is 40-80kHz, the ultrasound process is carried out under sunlight or simulated sunlight, the power of the simulated irradiation device is 300W, and stirring or aeration is continued during the degradation process.

8. Application of the ultrasound-enhanced red mud-based catalytic material degradation method according to any one of claims 1 to 7 in degrading pollutants in industrial wastewater or domestic sewage.

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