A method for preparing a biochar-supported manganese sulfide composite catalyst, the catalyst and its application.

Abstract

A method for preparing a biochar-supported manganese sulfide composite catalyst includes the following steps: S1, coffee grounds are first naturally air-dried and then low-temperature dried, followed by calcination at 300-700℃ under N2 protection in a tube furnace, and then ground to obtain coffee grounds biochar; S2, 1,3,5-phenyltricarboxylic acid is dissolved in potassium hydroxide solution to obtain a first treatment solution, manganese acetate is completely dissolved in deionized water and added to the coffee grounds biochar prepared in step S1, and ultrasonic treatment is performed to obtain a second treatment solution. The first treatment solution is slowly added dropwise to the second treatment solution, and after mixing and reaction, a biochar-supported manganese-based MOF precursor is obtained; S3, ultrasonic dispersion is performed, thiourea is added and stirred, and a hydrothermal reaction is carried out to obtain the biochar-supported manganese sulfide composite catalyst. This invention also provides the prepared catalyst. This catalyst can efficiently catalyze the activation of PMS (peroxymonosulfate) in the effective degradation of levofloxacin wastewater.

Description

Technical Field

[0001] This invention belongs to the technical field of catalysts for treating levofloxacin-containing wastewater, specifically relating to a method for preparing a biochar-supported manganese sulfide composite catalyst, the catalyst itself, and its applications. Background Technology

[0002] As the harm of emerging pollutants to the ecological environment and human health becomes increasingly apparent, strengthening the treatment of these new pollutants has become an important measure for effectively preventing and controlling the environmental risks posed by toxic and hazardous chemicals. Levofloxacin is a typical quinolone antibiotic, and due to its antibacterial properties, traditional wastewater treatment technologies struggle to remove it. Therefore, there is an urgent need to develop a novel and highly efficient technology for removing antibiotics from water.

[0003] In recent years, persulfate-based advanced oxidation technologies have attracted widespread attention. Compared with traditional Fenton oxidation, which generates hydroxyl radicals (-OH), persulfate-based advanced oxidation technology is a powerful advanced oxidation technology capable of generating a variety of reactive species and has been extensively studied in pharmaceutical wastewater treatment. However, persulfates have weak self-decomposition capabilities, are consumed in large quantities, and have low mineralization capacity for antibiotics, making it difficult to meet practical application requirements. Catalysts are needed to activate them and improve their decomposition efficiency to accelerate the degradation of antibiotics, especially when treating levofloxacin in wastewater, where their decomposition effect is even more difficult to achieve.

[0004] Therefore, developing a new catalyst for activating peroxymonosulfate to improve the decomposition efficiency of levofloxacin is not only of urgent research value, but also has good economic benefits and industrial application potential. This is the driving force and basis for the completion of this invention. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art as mentioned above, the inventors conducted in-depth research and, after a great deal of creative work, completed this invention.

[0006] Specifically, the technical problem to be solved by the present invention is to provide a method for preparing a biochar-supported manganese sulfide composite catalyst, the catalyst and its application, so as to solve the technical problem that persulfate is very ineffective in removing levofloxacin from wastewater.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0008] A method for preparing a biochar-supported manganese sulfide composite catalyst is provided, comprising the following steps:

[0009] S1. After naturally drying the coffee grounds and then drying them at a low temperature, they are calcined in a tube furnace under N2 protection at 300-700℃ and then ground to obtain coffee ground biochar.

[0010] S2, 1,3,5-benzenetricarboxylic acid was dissolved in potassium hydroxide solution to obtain the first solution to be treated. Manganese acetate was completely dissolved in deionized water and then added to the prepared coffee grounds biochar. The solution was ultrasonically treated to obtain the second solution to be treated. The first solution to be treated was slowly added dropwise to the second solution to be treated. After mixing and reacting, a biochar-supported manganese-based MOF precursor was obtained.

[0011] S3. After ultrasonically dispersing the biochar-supported manganese-based MOF precursor in an ethanol solution for a certain period of time, thiourea was added and stirred. Finally, the suspension was transferred to a polytetrafluoroethylene-lined stainless steel autoclave and hydrothermally reacted at 120-170℃ to obtain the biochar-supported manganese sulfide composite catalyst.

[0012] Preferably, the coffee grounds are air-dried naturally and then dried in an oven at 60-70°C for 12 hours.

[0013] Preferably, the dried coffee grounds are calcined in a tube furnace at 300-700°C for 2 hours under a nitrogen atmosphere.

[0014] Preferably, the sieve mesh size for sieving the ground coffee grounds biochar is 200 mesh.

[0015] Preferably, the concentration of 1,3,5-benzenetricarboxylic acid is 0.26-0.32 mol / L, the concentration of manganese acetate is 0.12-0.18 mol / L, and the amount of coffee grounds biochar added is 0.5-1.5 g. Insufficient coffee grounds biochar will lead to severe pore blockage, while excessive addition will affect the manganese sulfide loading, resulting in a decrease in levofloxacin removal rate.

[0016] Preferably, the concentration of the potassium hydroxide solution is 1.0-2.0 mol / L.

[0017] Preferably, in step S2, the first liquid to be treated is added to the second liquid to be treated dropwise at a uniform rate using a peristaltic pump.

[0018] Preferably, in step S2, the volume ratio of the first liquid to be treated to the second liquid to be treated is 5-7:18-20. For example, the volume of the first liquid to be treated is 25-35 mL, and the volume of the second liquid to be treated is 90-100 mL.

[0019] Preferably, the biochar-loaded manganese-based MOF precursor obtained after the mixing reaction in step S2 is washed, vacuum dried, and then stored in a desiccator.

[0020] Preferably, in step S3, the biochar-supported manganese-based MOF precursor is ultrasonically dispersed in ethanol solution for 15-30 min, and the stirring time after adding thiourea is 10-20 min.

[0021] Preferably, in step S3, the mass ratio of biochar-supported manganese-based MOF precursor to thiourea is 1:1.0-1.5 to ensure complete conversion to manganese sulfide.

[0022] Preferably, the hydrothermal synthesis temperature in step S3 is 125-165°C, and in a preferred embodiment, the hydrothermal synthesis temperature is 155°C.

[0023] Preferably, the hydrothermal synthesis reaction time in step S3 is 6-10 hours.

[0024] Preferably, step S3 includes: ultrasonically dispersing 1.0g of biochar-supported manganese-based MOF precursor in 35mL of ethanol solution for 15-30min, adding 1.0-1.5g of thiourea and stirring for 10-20min, and finally transferring the suspension to a polytetrafluoroethylene-lined stainless steel autoclave and hydrothermally reacting it at 125-165℃ for 6-10h to obtain a biochar-supported manganese sulfide composite catalyst, which is then repeatedly washed, vacuum dried, and stored in a desiccator.

[0025] The biochar-supported manganese sulfide composite catalyst provided by this invention consists of nanorod-shaped manganese sulfide uniformly loaded onto a three-dimensional sponge-like biochar.

[0026] The catalyst provided by this invention is a biochar-supported manganese sulfide composite catalyst prepared by the above preparation method.

[0027] This invention also provides the application of the above-mentioned biochar-supported manganese sulfide composite catalyst in the activation of peroxymonosulfate to degrade levofloxacin in water.

[0028] Preferably, the biochar-supported manganese sulfide composite catalyst is mixed with levofloxacin wastewater in a reaction flask, and peroxymonosulfate is added to start the reaction.

[0029] Preferably, the levofloxacin concentration is between 0.5-2.0 mg / L, the dosage of the biochar-supported manganese sulfide composite catalyst is 0.04-0.08 g / L, and the concentration of peroxymonosulfate is 0.05-0.40 mM. In a preferred embodiment, the levofloxacin concentration is 1 mg / L, the composite catalyst dosage is 0.06 g / L, and the peroxymonosulfate concentration is 0.20 mM. If the levofloxacin concentration changes, the dosage of the catalyst and peroxymonosulfate can be adjusted to achieve good levofloxacin removal efficiency.

[0030] Preferably, the removal reaction time is between 5 and 90 minutes. More preferably, the reaction time is between 60 and 90 minutes.

[0031] Preferably, the biochar-supported manganese sulfide composite catalyst has good stability and reusability.

[0032] After adopting the above technical solution, the beneficial effects of the present invention are:

[0033] This invention uses coffee grounds, which are then rigorously processed to obtain coffee grounds biochar. The inventors discovered that coffee grounds biochar is the most effective material in this invention due to its rich porous structure, abundant availability, low cost, and simple design. The coffee grounds biochar possesses a unique three-dimensional sponge-like network structure, which effectively inhibits metal leaching and improves metal dispersion. This aligns with the other steps in the preparation of the biochar-supported manganese sulfide composite catalyst in this invention. The final biochar-supported manganese sulfide composite catalyst is composed of nanorod-shaped manganese sulfide, uniformly loaded onto the three-dimensional sponge-like coffee grounds biochar.

[0034] The preparation method of the biochar-supported manganese sulfide composite catalyst according to the present invention uses environmentally friendly raw materials, has a simple overall process, low reaction temperature, high safety, and low cost. The biochar-supported manganese sulfide composite catalyst obtained by the preparation method according to the present invention can efficiently catalyze the activation of PMS (peroxymonosulfate) in the effective degradation of levofloxacin wastewater. Furthermore, the biochar-supported manganese sulfide composite catalyst obtained by the preparation method according to the present invention is safe and environmentally friendly, easy to separate, highly stable, and highly reusable; its catalytic efficiency can be significantly restored after multiple uses by calcination.

[0035] Meanwhile, the use of biochar prepared from biomass as raw material to remediate water pollution in this invention also meets current requirements. Attached Figure Description

[0036] Figure 1 SEM image of the biochar-supported manganese sulfide composite catalyst according to Example 1 of the present invention;

[0037] Figure 2 The image shows the XRD pattern of the biochar-supported manganese sulfide composite catalyst according to Example 1 of the present invention.

[0038] Figure 3 This is a diagram illustrating the effect of biochar-supported manganese sulfide composite catalyst activating peroxymonosulfate to remove levofloxacin according to Example 1 of the present invention.

[0039] Figure 4 This study investigates the activation of peroxymonosulfate degradation of levofloxacin using a biochar-supported manganese sulfide composite catalyst according to Example 1 of the present invention, and its catalytic efficiency after regeneration. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments. However, the uses and purposes of these exemplary embodiments are only for illustrating the present invention and do not constitute any limitation on the actual scope of protection of the present invention, nor are they intended to limit the scope of protection of the present invention to these embodiments.

[0041] Example 1

[0042] A method for preparing a biochar-supported manganese sulfide composite catalyst includes the following steps:

[0043] S1. After the coffee grounds are naturally air-dried, they are dried in an oven at 65℃ for 12 hours. The dried coffee grounds are then calcined in a tube furnace under N2 protection at 10℃ / min to 500℃ for 2 hours. The coffee grounds are then ground to obtain coffee grounds biochar. The biochar is then sieved through a 200-mesh sieve.

[0044] S2. Dissolve 1.50g of 1,3,5-benzenetricarboxylic acid in 1M potassium hydroxide solution to obtain the first treatment solution (the concentration of 1,3,5-benzenetricarboxylic acid is 0.26mol / L). Dissolve 3.45g of manganese acetate tetrahydrate in deionized water and add 0.5g of the above coffee grounds biochar to obtain the second treatment solution (the concentration of manganese acetate is 0.12mol / L). Add 25ml of the first treatment solution dropwise to 90ml of the second treatment solution using a peristaltic pump. Stir and mix at room temperature for 24h. After washing with ethanol and deionized water multiple times, vacuum dry to obtain the biochar-supported manganese-based MOF precursor.

[0045] S3. 1.0 g of biochar-supported manganese-based MOF precursor was added to 35 mL of ethanol and ultrasonically dispersed for 20 min. Then, 1.5 g of thiourea was added and stirred for 15 min. The solution was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 155 °C for 8 h. After the reaction was completed, the mixture was centrifuged, washed multiple times with ethanol and deionized water, and then vacuum dried to obtain the biochar-supported manganese sulfide composite catalyst.

[0046] This embodiment yielded a biochar-supported manganese sulfide composite catalyst, the SEM image of which is shown below. Figure 1 As shown, its X-ray diffraction pattern is as follows: Figure 2 As shown, the biochar-supported manganese sulfide composite catalyst prepared in this embodiment is a nanorod-shaped manganese sulfide uniformly loaded on a three-dimensional sponge-like biochar.

[0047] Example 2

[0048] S1. After the coffee grounds are naturally air-dried, they are dried in an oven at 60℃ for 12 hours. The dried coffee grounds are then calcined in a tube furnace under N2 protection at 10℃ / min to 500℃ for 2 hours, and then ground to obtain coffee ground biochar.

[0049] S2. Dissolve 1.50g of 1,3,5-benzenetricarboxylic acid in 1M potassium hydroxide solution to obtain the first treatment solution (the concentration of 1,3,5-benzenetricarboxylic acid is 0.32mol / L). Dissolve 3.45g of manganese acetate tetrahydrate in deionized water and add 1.5g of the above coffee grounds biochar to obtain the second treatment solution (the concentration of manganese acetate is 0.18mol / L). Add 35ml of the first treatment solution dropwise to 100ml of the second treatment solution using a peristaltic pump. Stir and mix at room temperature for 24h. After washing with ethanol and deionized water multiple times, vacuum dry to obtain the biochar-supported manganese-based MOF precursor.

[0050] S3. 1.0 g of biochar-supported manganese-based MOF precursor was added to 35 mL of ethanol and ultrasonically dispersed for 30 min. Then, 1.5 g of thiourea was added and stirred for 10 min. The solution was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 165 °C for 6 h. After the reaction was completed, the mixture was centrifuged, washed multiple times with ethanol and deionized water, and then vacuum dried to obtain the biochar-supported manganese sulfide composite catalyst.

[0051] In this embodiment, a biochar-supported manganese sulfide composite catalyst was obtained, which is also a nanorod-shaped manganese sulfide uniformly loaded on a three-dimensional sponge network biochar.

[0052] Example 3

[0053] S1. After the coffee grounds are naturally air-dried, they are dried in an oven at 63℃ for 12 hours. The dried coffee grounds are then calcined in a tube furnace under N2 protection at 10℃ / min to 300℃ for 2 hours, and then ground to obtain coffee ground biochar.

[0054] S2. Dissolve 1.50g of 1,3,5-benzenetricarboxylic acid in 1M potassium hydroxide solution to obtain the first treatment solution (the concentration of 1,3,5-benzenetricarboxylic acid is 0.30mol / L). Dissolve 3.45g of manganese acetate tetrahydrate in deionized water and add 1.0g of the above coffee grounds biochar to obtain the second treatment solution (the concentration of manganese acetate is 0.15mol / L). Add 30ml of the first treatment solution dropwise to 95ml of the second treatment solution using a peristaltic pump. Stir and mix at room temperature for 24h. After washing with ethanol and deionized water multiple times, vacuum dry to obtain the biochar-supported manganese-based MOF precursor.

[0055] S3. 1.0 g of biochar-supported manganese-based MOF precursor was added to 35 mL of ethanol and ultrasonically dispersed for 30 min. Then, 1.5 g of thiourea was added and stirred for 20 min. The solution was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 155 °C for 8 h. After the reaction was completed, the mixture was centrifuged, washed multiple times with ethanol and deionized water, and then vacuum dried to obtain the biochar-supported manganese sulfide composite catalyst.

[0056] In this embodiment, a biochar-supported manganese sulfide composite catalyst was obtained, which is also a nanorod-shaped manganese sulfide uniformly loaded on a three-dimensional sponge network biochar.

[0057] Example 4

[0058] S1. After the coffee grounds are naturally air-dried, they are dried in an oven at 70℃ for 12 hours. The dried coffee grounds are then calcined in a tube furnace under N2 protection at 10℃ / min to 700℃ for 2 hours, and then ground to obtain coffee ground biochar.

[0059] S2. Dissolve 1.50g of 1,3,5-benzenetricarboxylic acid in 1M potassium hydroxide solution to obtain the first treatment solution (the concentration of 1,3,5-benzenetricarboxylic acid is 0.26mol / L). Dissolve 3.45g of manganese acetate tetrahydrate in deionized water and add 1.2g of the above coffee grounds biochar to obtain the second treatment solution (the concentration of manganese acetate is 0.17mol / L). Add 30ml of the first treatment solution dropwise to 100ml of the second treatment solution using a peristaltic pump. Stir and mix at room temperature for 24h. After washing with ethanol and deionized water multiple times, vacuum dry to obtain the biochar-supported manganese-based MOF precursor.

[0060] S3. 1.0 g of biochar-supported manganese-based MOF precursor was added to 35 mL of ethanol and ultrasonically dispersed for 20 min. Then, 1.5 g of thiourea was added and stirred for 15 min. The solution was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 120 °C for 10 h. After the reaction was completed, the mixture was centrifuged, washed multiple times with ethanol and deionized water, and then vacuum dried to obtain the biochar-supported manganese sulfide composite catalyst.

[0061] In this embodiment, a biochar-supported manganese sulfide composite catalyst was obtained, which is also a nanorod-shaped manganese sulfide uniformly loaded on a three-dimensional sponge network biochar.

[0062] Example 5

[0063] S1. After the coffee grounds are naturally air-dried, they are dried in an oven at 60℃ for 12 hours. The dried coffee grounds are then calcined in a tube furnace under N2 protection at 10℃ / min to 700℃ for 2 hours. The resulting coffee grounds biochar is then ground.

[0064] S2. Dissolve 1.50g of 1,3,5-benzenetricarboxylic acid in 1M potassium hydroxide solution to obtain the first treatment solution (the concentration of 1,3,5-benzenetricarboxylic acid is 0.30mol / L). Dissolve 3.45g of manganese acetate tetrahydrate in deionized water and add 1.2g of the above coffee grounds biochar to obtain the second treatment solution (the concentration of manganese acetate is 0.12mol / L). Add 35ml of the first treatment solution dropwise to 90ml of the second treatment solution using a peristaltic pump. Stir and mix at room temperature for 24h. After washing with ethanol and deionized water multiple times, vacuum dry to obtain the biochar-supported manganese-based MOF precursor.

[0065] S3. 1.0 g of biochar-supported manganese-based MOF precursor was added to 35 mL of ethanol and ultrasonically dispersed for 20 min. Then, 1.0 g of thiourea was added and stirred for 20 min. The solution was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 150 °C for 8 h. After the reaction was completed, the mixture was centrifuged, washed multiple times with ethanol and deionized water, and then vacuum dried to obtain the biochar-supported manganese sulfide composite catalyst.

[0066] In this embodiment, a biochar-supported manganese sulfide composite catalyst was obtained, which is also a nanorod-shaped manganese sulfide uniformly loaded on a three-dimensional sponge network biochar.

[0067] Application Example 1

[0068] First, 100 mL of a 1 mg / L levofloxacin solution was measured into an Erlenmeyer flask. The biochar-supported manganese sulfide composite catalyst prepared in Example 1 was added to the LVF (levofloxacin) solution (the concentration of the biochar-supported manganese sulfide composite catalyst in this solution was 0.06 g / L), and magnetic stirring was started. Then, peroxymonosulfate (the concentration of peroxymonosulfate in the solution was 0.20 mM) was added to trigger the reaction. Samples were taken at different time intervals for analysis. The removal rate of levofloxacin is shown in the attached figure. Figure 3 As shown, the removal capacity of biochar-supported manganese sulfide composite catalyst alone for levofloxacin is negligible, and PMS alone cannot effectively remove levofloxacin (removal rate of about 18%). However, when biochar-supported manganese sulfide composite catalyst is used as an activator together with peroxymonosulfate, the degradation efficiency of levofloxacin reaches 91.6% within 60 min and 92.1% within 90 min.

[0069] Therefore, the biochar-supported manganese sulfide composite catalyst prepared by the method of the present invention can efficiently catalyze and activate PMS to effectively degrade levofloxacin wastewater.

[0070] The application results of the biochar-supported manganese sulfide composite catalysts prepared in other embodiments are basically consistent with those in Application Example 1.

[0071] Application Example 2

[0072] The catalyst, after reacting using the same steps as in Example 1, was filtered and separated, washed three times each with deionized water and ethanol, and then dried under vacuum at 60°C. Multiple reuse experiments and regeneration activity experiments were then conducted. The experimental results are attached. Figure 4 As shown.

[0073] This demonstrates that the biochar-supported manganese sulfide composite catalyst of the present invention is reusable and regenerable.

[0074] The application results of the biochar-supported manganese sulfide composite catalysts prepared in other embodiments are basically consistent with those in Application Example 2.

[0075] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention. Furthermore, it should be understood that after reading the technical description of this invention, those skilled in the art can make various alterations, modifications, and / or variations to the invention, and all such equivalent forms also fall within the scope of protection defined by the appended claims.

Claims

1. A method for preparing a biochar-supported manganese sulfide composite catalyst, characterized in that: The preparation method includes the following steps: S1. After the coffee grounds are naturally air-dried, they are dried in an oven at 60-70℃ for 12 hours, and then calcined in a tube furnace at 300-700℃ for 2 hours under N2 protection. The coffee grounds biochar is then ground. S2, 1,3,5-benzenetricarboxylic acid is dissolved in potassium hydroxide solution to obtain the first solution to be treated. Manganese acetate is completely dissolved in deionized water and then added to the coffee grounds biochar prepared in step S1. The solution is ultrasonically treated to obtain the second solution to be treated. The first solution to be treated is slowly added dropwise to the second solution to be treated, and the volume ratio of the first solution to the second solution to be treated is 5-7:18-20. After mixing and reacting, a biochar-supported manganese-based MOF precursor is obtained. S3. The biochar-supported manganese-based MOF precursor prepared in step S2 is ultrasonically dispersed in an ethanol solution for 15-30 min, then thiourea is added and stirred for 10-20 min. Finally, the suspension is transferred to a polytetrafluoroethylene-lined stainless steel autoclave and hydrothermally reacted at 120-170℃ to obtain the biochar-supported manganese sulfide composite catalyst.

2. The method for preparing a biochar-supported manganese sulfide composite catalyst according to claim 1, characterized in that, In step S2, the concentration of 1,3,5-benzenetricarboxylic acid is 0.26-0.32 mol / L, the concentration of manganese acetate is 0.12-0.18 mol / L, and the amount of coffee grounds biochar added is 0.5-1.5 g.

3. The method for preparing a biochar-supported manganese sulfide composite catalyst according to claim 2, characterized in that, In step S3, the mass ratio of biochar-supported manganese-based MOF precursor to thiourea is 1:1.0-1.

5.

4. The method for preparing a biochar-supported manganese sulfide composite catalyst according to claim 3, characterized in that, In step S3, the hydrothermal synthesis reaction time is 6-10 hours.

5. A catalyst, characterized in that, It is prepared by the method for preparing a biochar-supported manganese sulfide composite catalyst as described in any one of claims 1-4.

6. Application of the catalyst as described in claim 5 in the degradation of levofloxacin by activated peroxymonosulfate.

7. The application according to claim 6, characterized in that, The concentration of levofloxacin was between 0.5 and 2.0 mg / L, the dosage of biochar-supported manganese sulfide composite catalyst was 0.04-0.08 g / L, and the concentration of peroxymonosulfate was 0.05-0.40 mM.

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