Preparation method of metal modified biomass charcoal catalyst and application of metal modified biomass charcoal catalyst in pollutant degradation

Abstract

According to the preparation method of the metal modified biomass charcoal catalyst and the application of the metal modified biomass charcoal catalyst to pollutant degradation, the catalyst is prepared by adopting a carbonization method, and tetracycline wastewater is degraded by activating persulfate by utilizing the catalyst. Anhydrous ferric trichloride is used as an iron source, sugarcane leaves are used as a carbon source, the raw material ratio of the anhydrous ferric trichloride to the sugarcane leaves to urea to sodium hydroxide to ultrapure water is 810: 5: 25: 12: 30, and the raw materials are uniformly mixed, dried and sieved. And placing the mixture sample in a tubular furnace, and keeping at 800 DEG C for 2 hours to obtain a catalyst sample. The initial concentration of tetracycline hydrochloride is 20 mg / L, the pH value is 7.0, the concentration of sodium persulfate is 0.5 mM, the concentration of the catalyst is 0.1 g / L, and the degradation rate reaches 87%. The conclusion shows that the modified catalyst prepared from the biomass charcoal loaded iron can effectively catalyze persulfate to degrade tetracycline wastewater.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically, to a tetracycline wastewater treatment process based on modified biochar catalytic oxidation. Background Technology

[0002] Currently, biochar has been widely used in wastewater treatment and soil improvement. As a catalyst, biochar can activate oxidants such as persulfate and hydrogen peroxide to generate free radicals that degrade pollutants. Studies have shown that environmentally persistent free radicals (EPFRs) in biochar have a significant impact on the active substances in the catalytic system, mediating free radical-based redox processes through electron transfer. This demonstrates a significant effect on the degradation of pollutants using both free radicals and non-free radicals in wastewater treatment. Adding magnetic materials during the preparation of biochar imbues it with magnetism, facilitating recycling after use.

[0003] With the rapid increase in demand for activated carbon, the shortage of raw materials for its production has become increasingly prominent. Therefore, finding new renewable raw materials for activated carbon production has become a research hotspot. Currently, research on sugarcane leaves is limited; they are mainly used for animal husbandry and as adsorption materials, and are mostly used as fuel, leading to serious environmental pollution. Summary of the Invention

[0004] To further achieve rational resource utilization and reduce environmental pollution, this study aims to provide a method for preparing a metal-supported biochar modified catalyst and its application in pollutant degradation, and to explore its feasibility in the advanced treatment of tetracycline wastewater.

[0005] The solution provided by this invention is as follows: This invention provides a method for preparing modified biochar supported on metal biomass, which is prepared by carbonization reaction of iron and sugarcane leaves, with anhydrous ferric chloride as the iron source and sugarcane leaves as the carbon source.

[0006] Step 1: Select fresh, pest-free sugarcane leaves as raw materials, wash, dry, grind, and sieve them to obtain sugarcane leaf powder; Step 2: The raw material ratios are: anhydrous ferric chloride: sugarcane leaves: urea: sodium hydroxide: ultrapure water = 0:5:25:12:30, 40:5:25:12:30, 200:5:25:12:30 and 810:5:25:12:30. Mix thoroughly on a magnetic stirrer, set the temperature to 80℃, stir, evaporate and dry, then grind through a 60-mesh sieve to obtain a mixed sample. Step 3: Compact the mixture in a ceramic boat, place it in a tube furnace, and purge with nitrogen at 0.2 L / min for 20 min to fill the furnace with nitrogen. Heat to 500-900℃ at a rate of 5℃ / min, and maintain for 1-3 h. After calcination, cool to room temperature, grind, and sieve to obtain the catalyst sample. Calcinate the mixture at high temperature under nitrogen, and after cooling to room temperature, obtain the carbon sample.

[0007] The beneficial effects of this invention are: This invention prepared iron-modified biochar as a catalyst, and studied the treatment of tetracycline wastewater using the prepared catalyst. The results showed that the catalyst activated persulfate to degrade tetracycline hydrochloride at a degradation rate of 87%. Attached Figure Description

[0008] Figure 1 It is an X-ray diffraction pattern.

[0009] Figure 2 It is the effect of different iron contents in the catalyst.

[0010] Figure 3 It is due to the effect of different calcination temperatures.

[0011] Figure 4 It is due to the effect of different calcination times.

[0012] Figure 5 This is due to the effect of different catalyst concentrations.

[0013] Figure 6 This is due to the effect of different PDS concentrations.

[0014] Figure 7 It is the effect of different initial concentrations of tetracycline hydrochloride.

[0015] Figure 8 It is the effect of different pH values.

[0016] Figure 9 It is the effect of different inorganic ions.

[0017] Figure 10 This is a graph showing the degradation effects of different tetracycline antibiotics. Detailed Implementation Plan

[0018] The present invention will be described in more detail below through implementation examples, but the following implementations are merely illustrative and the scope of protection of the present invention is not limited to these implementation examples.

[0019] This invention provides a metal-modified biochar catalyst with the following raw material ratios: anhydrous ferric chloride: sugarcane leaves: urea: sodium hydroxide: ultrapure water = 0:5:25:12:30, 40:5:25:12:30, 200:5:25:12:30 and 810:5:25:12:30 (wherein, the iron content corresponds to 0, 0.05, 0.25 and 1.0 M, respectively).

[0020] Compared with existing technologies, the metal-modified biochar catalyst provided by this invention utilizes sugarcane leaves and anhydrous ferric chloride from plant waste as raw materials, and is prepared through a reaction. Specifically, ferric ions have low catalytic activity. During the co-carbonization process of anhydrous ferric chloride and sugarcane leaves, biocharification can reduce some of the ferric ions in ferric chloride to lower valence states of iron ions, thereby improving the catalytic activity of the carbon material and obtaining a metal-modified biochar catalyst.

[0021] This invention also provides a method for preparing a metal-modified biochar catalyst, comprising the following steps: Step 1: Place anhydrous ferric chloride and sugarcane leaves in a beaker, add urea, sodium hydroxide and ultrapure water and mix well (raw material ratio is: anhydrous ferric chloride: sugarcane leaves: urea: sodium hydroxide: ultrapure water = 0:5:25:12:30, 40:5:25:12:30, 200:5:25:12:30 and 810:5:25:12:30), dry and pass through a 60-mesh sieve to obtain the mixture; Step 2: Heat the mixture and react it under an inert atmosphere (nitrogen) to obtain the reaction product; Step 3: The reaction product is cooled and sieved to obtain the metal-modified biochar catalyst.

[0022] To improve the catalytic activity of the metal-modified biochar catalyst, in step 1 above, the sugarcane leaves are passed through a 60-mesh sieve. This is because the particle size of sugarcane leaves and anhydrous ferric chloride is too large, resulting in a small specific surface area. This leads to reduced contact between the metal and the sugarcane leaf mud, resulting in incomplete reaction. Furthermore, using large-particle sugarcane leaves and anhydrous ferric chloride as raw materials results in a biochar catalyst with a relatively small specific surface area and low catalytic activity.

[0023] To achieve a uniform mixture of metal and sugarcane leaves, in step 1 above, the raw material ratios are: anhydrous ferric chloride: sugarcane leaves: urea: sodium hydroxide: ultrapure water = 0:5:25:12:30, 40:5:25:12:30, 200:5:25:12:30 and 810:5:25:12:30. Different ratios are mixed, and then dried at 80°C until completely dry.

[0024] In order to control the reaction rate of the carbonization reaction, in step 2 above, the heating temperature is 500-900℃ and the heating rate is 5℃ / min.

[0025] Specifically, step 2 above includes the following steps: Step 4: Before high-temperature calcination, first introduce nitrogen gas for 20 minutes to fill the tubular furnace with nitrogen gas.

[0026] Step 5: Heat to 500℃-900℃ at a heating rate of 5℃ / min and hold for 1-3 hours. The modified biochar becomes porous biochar, and the ferric ions in anhydrous ferric chloride are reduced to ferrous ions, thereby obtaining the reaction product.

[0027] This invention also provides an application of a metal-modified biochar catalyst for pollutant degradation, comprising the following steps: Step a: Mix the metal-modified biochar catalyst, the aqueous solution of organic pollutants, and the oxidant, wherein the oxidant is persulfate (sodium persulfate).

[0028] Step b: Stir the mixture obtained in step a to degrade the organic pollutants in the aqueous solution.

[0029] It should be noted that the above-mentioned pollutant degradation method utilizes the reaction of low-valent iron in metal-modified biochar catalysts with oxidants to generate highly oxidizing hydroxyl radicals or sulfate radicals, as well as superoxide anions and singlet oxygen, thereby oxidizing and degrading organic pollutants in water. The degradation of organic pollutants by free radicals is non-selective, and highly oxidizing free radicals can basically degrade most organic pollutants.

[0030] Specifically, for the metal-modified biochar catalyst, the aqueous solution of organic pollutants, and the oxidant, step a above includes the following steps: adding the metal-modified biochar catalyst and the oxidant to the aqueous solution of organic pollutants and stirring for 90 minutes.

[0031] Specifically, the dosage of metal-modified biochar catalyst is 0.02-1.0 g per liter of aqueous solution containing organic pollutants. Example

[0032] The sugarcane leaf particles used in the metal-modified biochar catalyst of this embodiment have all passed through a 60-mesh sieve. The preparation method of the metal-modified biochar catalyst is as follows: Step 1: Mix anhydrous ferric chloride, sugarcane leaves, urea, sodium hydroxide and ultrapure water evenly to obtain a mixture with a mass ratio of 0:5:25:12:30; Step 2: Before high-temperature calcination, nitrogen gas is introduced for 20 minutes to fill the tubular furnace with nitrogen. The temperature is then increased to 800°C at a rate of 5°C / min and held for 2 hours, resulting in porous biochar.

[0033] Step 3: Cool and sieve the reaction product to obtain the metal-modified biochar catalyst. Example

[0034] The sugarcane leaf particles used in the metal-modified biochar catalyst of this embodiment have all passed through a 60-mesh sieve. The preparation method of the metal-modified biochar catalyst is as follows: Step 1: Mix anhydrous ferric chloride, sugarcane leaves, urea, sodium hydroxide and ultrapure water evenly to obtain a mixture with a mass ratio of 40:5:25:12:30; Step 2: Before high-temperature calcination, nitrogen gas is introduced for 20 minutes to fill the tubular furnace with nitrogen. The temperature is increased to 800℃ at a rate of 5℃ / min and held for 2 hours. The modified biochar becomes porous biochar, and the iron oxide in the red mud is reduced to low-valence iron, thus obtaining the reaction products.

[0035] Step 3: Cool and sieve the reaction product to obtain the metal-modified biochar catalyst. Example

[0036] The red mud and papermaking sludge particles used in the metal-modified biochar catalyst of this embodiment have both passed through a 200-mesh sieve. The preparation method of the metal-modified biochar catalyst is as follows: Step 1: Mix anhydrous ferric chloride, sugarcane leaves, urea, sodium hydroxide and ultrapure water evenly to obtain a mixture with a mass ratio of 200:5:25:12:30; Step 2: Before high-temperature calcination, nitrogen gas is introduced for 20 minutes to fill the tube furnace with nitrogen. The temperature is increased to 800℃ at a rate of 5℃ / min and held for 2 hours. The modified biochar becomes porous biochar, and the ferric ions in anhydrous ferric chloride are reduced to ferric ions, thus obtaining the reaction product.

[0037] Step 3: Cool and sieve the reaction product to obtain the metal-modified biochar catalyst. Example

[0038] The sugarcane leaf particles used in the metal-modified biochar catalyst of this embodiment have all passed through a 60-mesh sieve. The preparation method of the metal-modified biochar catalyst is as follows: Step 1: Mix anhydrous ferric chloride, sugarcane leaves, urea, sodium hydroxide and ultrapure water evenly to obtain a mixture with a mass ratio of 810:5:25:12:30; Step 2: Before high-temperature calcination, nitrogen gas is introduced for 20 minutes to fill the tube furnace with nitrogen. The temperature is increased to 800℃ at a rate of 5℃ / min and held for 2 hours. The modified biochar becomes porous biochar, and the ferric ions in anhydrous ferric chloride are reduced to ferric ions, thus obtaining the reaction product.

[0039] Step 3: Cool and sieve the reaction product to obtain the metal-modified biochar catalyst. Example

[0040] The sugarcane leaf particles used in the metal-modified biochar catalyst of this embodiment have all passed through a 60-mesh sieve. The preparation method of the metal-modified biochar catalyst is as follows: Step 1: Mix anhydrous ferric chloride, sugarcane leaves, urea, sodium hydroxide and ultrapure water evenly to obtain a mixture with a mass ratio of 810:5:25:12:30; Step 2: Before high-temperature calcination, nitrogen gas is introduced for 20 minutes to fill the tube furnace with nitrogen. The temperature is then increased to 500°C at a rate of 5°C / min and held for 2 hours to obtain the reaction product.

[0041] Step 3: The reaction products are cooled sequentially to obtain metal-modified biochar catalyst. Example

[0042] The sugarcane leaf particles used in the metal-modified biochar catalyst of this embodiment have all passed through a 60-mesh sieve. The preparation method of the metal-modified biochar catalyst is as follows: Step 1: Mix anhydrous ferric chloride, sugarcane leaves, urea, sodium hydroxide and ultrapure water evenly to obtain a mixture with a mass ratio of 810:5:25:12:30; Step 2: Before high-temperature calcination, nitrogen gas is introduced for 20 minutes to fill the tube furnace with nitrogen. The temperature is then increased to 600°C at a rate of 5°C / min and held for 2 hours to obtain the reaction product.

[0043] Step 3: The reaction products are cooled sequentially to obtain metal-modified biochar catalyst. Example

[0044] The sugarcane leaf particles used in the metal-modified biochar catalyst of this embodiment have all passed through a 60-mesh sieve. The preparation method of the metal-modified biochar catalyst is as follows: Step 1: Mix anhydrous ferric chloride, sugarcane leaves, urea, sodium hydroxide and ultrapure water evenly to obtain a mixture with a mass ratio of 810:5:25:12:30; Step 2: Before high-temperature calcination, nitrogen gas is introduced for 20 minutes to fill the tube furnace with nitrogen. The temperature is then increased to 700°C at a rate of 5°C / min and held for 2 hours to obtain the reaction product.

[0045] Step 3: The reaction products are cooled sequentially to obtain metal-modified biochar catalyst. Example

[0046] The sugarcane leaf particles used in the metal-modified biochar catalyst of this embodiment have all passed through a 60-mesh sieve. The preparation method of the metal-modified biochar catalyst is as follows: Step 1: Mix anhydrous ferric chloride, sugarcane leaves, urea, sodium hydroxide and ultrapure water evenly to obtain a mixture with a mass ratio of 810:5:25:12:30; Step 2: Before high-temperature calcination, nitrogen gas is introduced for 20 minutes to fill the tube furnace with nitrogen. The temperature is then increased to 900°C at a rate of 5°C / min and held for 2 hours to obtain the reaction product.

[0047] Step 3: The reaction products are cooled sequentially to obtain metal-modified biochar catalyst.

[0048] The optimal preparation method for iron-modified biochar catalyst was determined through experiments: the raw material ratio was anhydrous ferric chloride: sugarcane leaves: urea: sodium hydroxide: ultrapure water = 810:5:25:12:30. The mixture was thoroughly mixed and magnetically stirred and dried at 80℃ for 24 hours. After stirring and evaporation, the mixture was ground and passed through a 60-mesh sieve. The mixture sample was compacted in a ceramic boat and placed in a tube furnace. Nitrogen gas was introduced at a rate of 0.2 L / min for 20 min, and the temperature was increased from room temperature to 800℃ at a rate of 5℃ / min, held for 2 hours, and a black sample was obtained. After grinding, the sample was passed through a 60-mesh sieve to obtain the catalyst sample.

[0049] This experiment determined the optimal conditions for treating tetracycline wastewater as follows: an initial tetracycline hydrochloride concentration of 20 mg / L, a pH of 7.0, a sodium persulfate concentration of 0.5 mM, a catalyst concentration of 0.1 g / L, and a degradation rate of 87% within 90 min.

[0050] In this experiment simulating tetracycline wastewater, different pH values ​​had no effect on its degradation effect, indicating that the catalyst material is applicable to a wide range of pH values; the degradation effect was less affected by the presence of different inorganic ions, indicating that the material is suitable for natural water bodies.

[0051] In this experiment, the material showed a significant degradation effect in simulated oxytetracycline wastewater, indicating that it is suitable for the degradation of tetracycline antibiotics.

Claims

1. A method for preparing a metal-supported biochar-modified catalyst and its application in pollutant degradation, characterized in that, The catalyst was prepared by mixing raw materials in the following ratios: anhydrous ferric chloride: sugarcane leaves: urea: sodium hydroxide: ultrapure water = 0:5:25:12:30, 40:5:25:12:30, 200:5:25:12:30, and 810:5:25:12:

30. After mixing and drying, the mixture was sieved and placed in a tube furnace at 500-900℃ for 1-3 h to obtain catalyst samples. The tetracycline wastewater concentration was 20-40 mg / L, the initial pH was 5.0-9.0, the sodium persulfate concentration was 0.1-0.5 mM, and the catalyst concentration was 0.02-0.1 g / L. The reaction was stirred at 370 rpm using a magnetic stirrer.

2. The process as described in claim 1, characterized in that, The raw material ratio is: anhydrous ferric chloride: sugarcane leaves: urea: sodium hydroxide: ultrapure water = 810:5:25:12:

30.

3. The process as described in claim 1, characterized in that, The calcination temperature is 800℃.

4. The process as described in claim 1, characterized in that, The calcination time is 2 hours.

5. The process as described in claim 1, characterized in that, The concentration of the tetracycline wastewater was 20 mg / L.

6. The process as described in claim 1, characterized in that, The pH value is 7.

0.

7. The process as described in claim 1, characterized in that, The sodium persulfate concentration is 0.5 mM.

8. The process as described in claim 1, characterized in that, The catalyst concentration is 0.1 g / L.

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