Preparation method of algal biochar-based catalyst and wastewater treatment method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANHUA UNIV
- Filing Date
- 2022-11-02
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies are difficult to remove tetracycline from wastewater efficiently and at low cost. Traditional carbon-based catalysts are complex to prepare and expensive, and biochar activation of persulfate is inefficient and difficult to apply.
Using wakame seaweed biochar as raw material, an iron- and nitrogen-modified biochar-based catalyst was prepared by doping with iron and nitrogen elements. This catalyst was used to activate persulfate degradation of antibiotics. The steps included hydrothermal reaction, calcination, and acid washing to form a highly efficient catalyst.
It achieves efficient degradation of tetracycline under mild conditions, with a degradation rate of over 85%, simplifying the preparation process and reducing costs.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater treatment method.
[0002] This invention relates to the field of carbon-based catalyst preparation technology, and in particular to a method for preparing an algal biochar-based catalyst. Background Technology
[0003] Antibiotics are chemical agents widely used to treat human and animal diseases, as well as microbial infectious diseases in aquaculture. Recently, they have been recognized as emerging pollutants and have attracted widespread attention. Tetracycline (TC) is one such antibiotic used and produced; residual TC in wastewater not only pollutes the environment but also endangers human health. Furthermore, due to its antibacterial properties and stable chemical structure, complete removal of TC using traditional methods such as adsorption and biodegradation is difficult. Therefore, developing low-cost, high-efficiency TC removal technologies is urgently needed.
[0004] In recent years, advanced oxidation processes have been widely used in the treatment of antibiotic wastewater due to their high oxidation efficiency and environmental friendliness. Commonly used oxidants in advanced oxidation processes include hydrogen peroxide, ozone, and persulfate. Among these, persulfate has attracted increasing attention due to its high stability, high reactivity, and high potential for generating free radicals.
[0005] Currently, commonly used activation methods include UV activation, ultrasonic activation, electrolytic activation, and catalysts. Among these, the use of highly efficient catalysts to activate persulfate has attracted attention due to its advantages of low energy consumption and high efficiency. Patent CN114105214A discloses a method for activating persulfate using CoWO4 ultrathin nanosheets, achieving a maximum tetracycline degradation rate of 82.8%. Patent CN112374601A discloses a method for activating persulfate with a magnetic nitrogen-doped carbon (Co-N / C) catalyst to degrade tetracycline in wastewater, achieving a tetracycline removal rate of 85.4% in 15 minutes. However, the above catalysts inevitably suffer from drawbacks such as complex preparation processes and expensive raw materials, which limit their application in actual production. Carbon-based catalysts, as highly efficient, stable, and environmentally friendly catalysts, exhibit excellent performance in activating PMS. However, commercially available carbon-based materials such as graphene, carbon nanotubes, and nanodiamonds are complex to prepare and expensive. Biochar, as a novel material, is widely available and inexpensive, making it a high-quality material for catalyst preparation. Traditional biochar has low activation efficiency for persulfate, making it difficult to apply. Compared to most terrestrial biochar, algal biochar has a higher nitrogen and phosphorus content, which can improve the performance of the prepared biochar catalyst.
[0006] Based on the above situation, the preparation of biochar-based catalysts from algal biochar and their use in activating persulfate degradation of antibiotics has a very promising prospect. Summary of the Invention
[0007] The purpose of this invention is to provide a wastewater treatment method and a biochar-based catalyst for wastewater treatment.
[0008] This invention provides a method for preparing an algal biochar-based catalyst, the method comprising the following steps: using wakame biochar as a carbon source, and doping it with iron and nitrogen precursors to prepare an iron and nitrogen co-modified wakame biochar-based composite catalyst.
[0009] Furthermore, the method specifically includes the following steps:
[0010] Step 1: Soak dried wakame seaweed in deionized water, wash and remove impurities, then put it in a blower box to dry at a constant temperature. After drying, grind it into powder using a grinder.
[0011] Step 2: Mix the product obtained in Step 1 with deionized water and stir. Transfer the mixture to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, filter, wash and dry the resulting substance.
[0012] Step 3: Mix the product obtained in Step 2 with ferric nitrate nonahydrate, add deionized water, and perform ultrasonic dispersion and magnetic stirring. After the process, filter, wash, and dry the resulting product.
[0013] Step 4: Mix the product obtained in Step 3 with melamine, transfer it to a tube furnace for high-temperature calcination, and then wash the calcined product with dilute sulfuric acid. After completion, filter, wash and dry.
[0014] Step 5: The product obtained in Step 4 is calcined a second time, and the calcined product is ground to obtain the iron and nitrogen co-modified Undaria biochar-based composite catalyst.
[0015] Furthermore, the drying temperature in step one is 40–80℃, and the drying time is 4–12 hours.
[0016] Furthermore, the hydrothermal reaction time in step two is 300–600 min, and the reaction temperature is 100–250 °C.
[0017] Furthermore, in step three: the mass ratio of the product obtained in step two to ferric nitrate nonahydrate is 1:0.1 to 1.
[0018] Furthermore, in step four: the mass ratio of the product obtained in step three to melamine is 1:1 to 6.
[0019] Furthermore, the high-temperature calcination in step four and the secondary calcination in step five are the same, specifically: calcination in a tubular furnace, with a calcination temperature of 700–900℃, a heating rate of 2–10℃ / min, and a calcination time of 60–180min.
[0020] Furthermore, in step four: the pickling time is 4 to 12 hours, the temperature of the pickling oil bath is 60 to 100°C, and the acid used is 0.2 to 1M dilute sulfuric acid.
[0021] The present invention also provides a wastewater treatment method, wherein the above-mentioned iron and nitrogen co-modified wakame biochar-based composite catalyst is placed into the wastewater to be treated, ultrasonically dispersed, stirred for 10 to 30 minutes, and after reaching adsorption equilibrium, persulfate is added to start the reaction. The reaction temperature is 10 to 30°C and the reaction time is 1 to 60 minutes.
[0022] Furthermore, the mass ratio of the algal biochar-based catalyst to persulfate is 1:5 to 100.
[0023] The beneficial effects of this invention are: the prepared biomass carbon material catalyst can efficiently catalyze the activation of persulfate to degrade organic pollutants in water, realize the mineralization of target pollutants, and achieve a more ideal treatment effect.
[0024] The beneficial effects of this invention are as follows:
[0025] Using wakame seaweed as a biochar feedstock, an iron- and nitrogen-modified wakame-based biochar composite catalyst was prepared through steps including washing, grinding, hydrothermal reaction, impregnation, heteroatom doping, high-temperature carbonization, acid washing, and secondary calcination. The preparation route is simple and highly operable. The high nitrogen and phosphorus content of wakame seaweed provides the catalyst with numerous active sites, and the doping of iron and nitrogen atoms during the preparation process further enhances the catalyst's performance.
[0026] The iron- and nitrogen-modified *Wakame seaweed* biochar-based catalyst prepared in this invention, as a persulfate catalyst, possesses both excellent adsorption and catalytic properties. In the reaction system where this catalyst activates persulfate to degrade antibiotics, the catalyst primarily functions as an adsorbent in the initial stage of the reaction. Upon addition of persulfate to the system, the persulfate is activated by the catalyst, generating free radicals that degrade pollutants. Under mild reaction conditions, this catalyst can efficiently activate persulfate to degrade tetracycline wastewater, achieving a final degradation rate of over 85%.
[0027] Using iron and nitrogen to modify wakame biochar-based catalysts to activate persulfate-degraded antibiotic wastewater provides a new pathway for antibiotic degradation and also a new approach for the resource utilization of algae. Attached Figure Description
[0028] Figure 1 SEM image of the iron and nitrogen co-modified Undaria biochar-based catalyst prepared.
[0029] Figure 2 TEM image of the iron and nitrogen co-modified Undaria biochar-based catalyst prepared for use.
[0030] Figure 3 The removal rate curves of tetracycline by iron and nitrogen co-modified wakame biochar-based catalyst and its control group activated persulfate were obtained.
[0031] Figure 4 The removal rates of tetracycline in the activated persulfate system of the iron- and nitrogen-modified wakame biochar-based catalyst were obtained under different catalyst dosages. Detailed Implementation
[0032] The present invention will be further described below with reference to the embodiments.
[0033] Example 1
[0034] This example provides an algal biochar-based catalyst, specifically an iron and nitrogen co-modified Undaria pinnatifida biochar-based catalyst, prepared using the following method:
[0035] Step 1: Soak commercially available dried wakame seaweed in deionized water, wash and remove impurities, then transfer it to a blower box for constant temperature drying at 60℃ for 8 hours. After drying, grind it into powder using a pulverizer.
[0036] Step 2: Mix the product obtained in Step 1 with deionized water and stir. Transfer the mixture to a hydrothermal reactor for hydrothermal reaction at 190°C for 480 min. After the reaction is complete, filter, wash and dry the resulting substance.
[0037] Step 3: Mix 1g of the product obtained in Step 2 with 0.36g of ferric nitrate nonahydrate, add 60ml of deionized water, and disperse by ultrasonication for 1h and magnetic stirring for 4h. After the process, filter, wash and dry the resulting product.
[0038] Step 4: Mix the dried product obtained in Step 3 with melamine at a ratio of 1:4, transfer it to a tube furnace and calcine at 800℃ for 2 hours with a heating rate of 5℃ / min. The calcined product is then acid-washed with 0.5M sulfuric acid in an oil bath at 80℃ for 8 hours. After completion, the product is filtered, washed, and dried.
[0039] Step 5: The product obtained in Step 4 is subjected to a second calcination at 800℃ for 1 hour at a heating rate of 5℃ / min. After completion, the product is ground to obtain the iron and nitrogen co-modified Undaria biochar-based composite catalyst.
[0040] Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the iron- and nitrogen-modified Undaria pinnatifida biochar-based composite catalyst. The results are as follows: Figure 1 , Figure 2 As shown.
[0041] This embodiment also provides a method for applying the above-mentioned iron and nitrogen co-modified wakame seaweed biochar-based composite catalyst: 5 mg of the iron and nitrogen co-modified wakame seaweed biochar-based composite catalyst is placed in 95 ml of tetracycline wastewater to be treated, ultrasonically dispersed, and then stirred in a 25°C constant temperature water bath. After reaching adsorption equilibrium, 5 ml of persulfate solution is added to start the advanced oxidation system. The ultrasonic dispersion time is 5 min, the constant temperature water bath temperature is 25°C, the stirring time is 25 min, and the mass concentration ratio of catalyst, tetracycline, and persulfate in the system is 5:3:50.
[0042] The following comparison with the control group will illustrate this in detail:
[0043] The following systems were compared: one containing potassium persulfate and a blank Wakame biochar catalyst (PMS: 0.5 g / L, SM: 0.05 g / L); another containing potassium persulfate and an iron-modified Wakame biochar composite catalyst (PMS: 0.5 g / L, SM-Fe: 0.05 g / L); another containing potassium persulfate and a nitrogen-modified Wakame biochar composite catalyst (PMS: 0.5 g / L, SM-N: 0.05 g / L); and yet another containing potassium persulfate and an iron and nitrogen-modified Wakame biochar-based composite catalyst (PMS: 0.5 g / L, SM-Fe-N: 0.05 g / L). The above method was used to remove a 30 mg / L tetracycline solution (wastewater to be treated). 2 ml of solution was collected at time points of 1 min, 3 min, 5 min, 10 min, 15 min, 20 min, 30 min, and 60 min, filtered through a 0.45 μm filter membrane, and the concentration was determined spectrophotometrically. The results are as follows: Figure 3 As shown, the removal effects of the SM-N group and the SM-Fe group were similar and both were better than the SM group. The SM-Fe-N group had the best degradation effect, with a degradation rate of 87% for tetracycline after 60 min of reaction.
[0044] The preparation methods of each catalyst in the control group are as follows:
[0045] SM Group:
[0046] Step 1: Soak commercially available dried wakame seaweed in deionized water, wash and remove impurities, then transfer it to a blower box for constant temperature drying at 60℃ for 8 hours. After drying, grind it into powder using a pulverizer.
[0047] Step 2: Mix the product obtained in Step 1 with deionized water and stir. Transfer the mixture to a hydrothermal reactor for hydrothermal reaction at 190°C for 480 min. After the reaction is complete, filter, wash and dry the resulting substance.
[0048] Step 3: Transfer the product from Step 2 into a tube furnace and calcine at 800℃ for 2 hours with a heating rate of 5℃ / min. Wash the calcined product with 0.5M sulfuric acid in an oil bath at 80℃ for 8 hours. After completion, filter, wash, and dry.
[0049] Step 4: The product obtained in Step 3 is subjected to a second calcination at 800℃ for 1 hour at a heating rate of 5℃ / min. After the calcination is completed, the product is ground to obtain a blank Undaria pinnatifida biochar-based catalyst.
[0050] SM-Fe group:
[0051] Step 1: Soak commercially available dried wakame seaweed in deionized water, wash and remove impurities, then transfer it to a blower box for constant temperature drying at 60℃ for 8 hours. After drying, grind it into powder using a pulverizer.
[0052] Step 2: Mix the product obtained in Step 1 with deionized water and stir. Transfer the mixture to a hydrothermal reactor for hydrothermal reaction at 190°C for 480 min. After the reaction is complete, filter, wash and dry the resulting substance.
[0053] Step 3: Mix 1g of the product obtained in Step 2 with 0.36g of ferric nitrate nonahydrate, add 60ml of deionized water, and disperse by ultrasonication for 1h and magnetic stirring for 4h. After the process, filter, wash and dry the resulting product.
[0054] Step 4: Transfer the dried product obtained in Step 3 into a tube furnace and calcine at 800℃ for 2 hours with a heating rate of 5℃ / min. Wash the calcined product with 0.5M sulfuric acid in an oil bath at 80℃ for 8 hours. After completion, filter, wash and dry.
[0055] Step 5: The product obtained in Step 4 is subjected to a second calcination at 800℃ for 1 hour at a heating rate of 5℃ / min. After completion, the product is ground to obtain the iron-modified wakame biochar-based composite catalyst.
[0056] SM-N group:
[0057] Step 1: Soak commercially available dried wakame seaweed in deionized water, wash and remove impurities, then transfer it to a blower box for constant temperature drying at 60℃ for 8 hours. After drying, grind it into powder using a pulverizer.
[0058] Step 2: Mix the product obtained in Step 1 with deionized water and stir. Transfer the mixture to a hydrothermal reactor for hydrothermal reaction at 190°C for 480 min. After the reaction is complete, filter, wash and dry the resulting substance.
[0059] Step 3: Mix the dried product obtained in Step 3 with melamine at a ratio of 1:4, transfer it to a tube furnace and calcine at 800℃ for 2 hours with a heating rate of 5℃ / min. The calcined product is then acid-washed with 0.5M sulfuric acid in an oil bath at 80℃ for 8 hours. After completion, the product is filtered, washed, and dried.
[0060] Step 4: The product obtained in Step 3 is subjected to a second calcination at 800℃ for 1 hour at a heating rate of 5℃ / min. After completion, the product is ground to obtain the nitrogen-modified wakame biochar-based composite catalyst.
[0061] Application Example 1
[0062] Experiments on the oxidative degradation of persulfate catalyzed by different concentrations of catalysts
[0063] Different masses of the SM-Fe-N catalyst prepared in Example 1 were weighed and added to 95 ml of tetracycline solution. After ultrasonic dispersion, the solution was stirred in a constant temperature water bath at 25 °C. After reaching adsorption equilibrium, 5 ml of persulfate solution was added to start the advanced oxidation system. The tetracycline concentration in the system was 30 mg / L, the persulfate concentration was 0.5 g / L, the ultrasonic dispersion time was 5 min, the constant temperature water bath temperature was 25 °C, and the stirring time was 25 min. 2 ml of solution was taken at time points of 1 min, 3 min, 5 min, 10 min, 15 min, 20 min, 30 min, and 60 min, filtered through a 0.45 μm filter membrane, and the concentration was determined spectrophotometrically. The results are as follows: Figure 4 As shown, within the set catalyst dosage range, the removal effect on tetracycline increases with the increase of catalyst dosage.
[0064] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing an algal biochar-based catalyst, characterized in that, The method includes the following steps: Step 1: Soak dried wakame seaweed in deionized water, wash and remove impurities, then put it in a blower box to dry at a constant temperature. After drying, grind it into powder using a grinder. Step 2: Mix the product obtained in Step 1 with deionized water and stir. Transfer the mixture to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, filter, wash and dry the resulting substance. Step 3: Mix the product obtained in Step 2 with ferric nitrate nonahydrate, add deionized water, and perform ultrasonic dispersion and magnetic stirring. After the process, filter, wash, and dry the resulting product. Step 4: Mix the product obtained in Step 3 with melamine, transfer it to a tube furnace for high-temperature calcination, and then wash the calcined product with dilute sulfuric acid. After completion, filter, wash and dry. Step 5: The product obtained in Step 4 is calcined a second time, and the calcined product is ground to obtain the iron and nitrogen co-modified wakame biochar-based composite catalyst.
2. The method for preparing an algal biochar-based catalyst according to claim 1, characterized in that, The drying temperature in step one is 40-80℃, and the drying time is 4-12 hours.
3. The method for preparing an algal biochar-based catalyst according to claim 1, characterized in that, The hydrothermal reaction time in step two is 300–600 min, and the reaction temperature is 100–250 °C.
4. The method for preparing an algal biochar-based catalyst according to claim 1, characterized in that, In step three: the mass ratio of the product obtained in step two to ferric nitrate nonahydrate is 1:0.1 to 1.
5. The method for preparing an algal biochar-based catalyst according to claim 1, characterized in that, In step four: the mass ratio of the product obtained in step three to melamine is 1:1 to 6.
6. The method for preparing an algal biochar-based catalyst according to claim 1, characterized in that, The high-temperature calcination in step four and the secondary calcination in step five are the same, specifically: calcination in a tubular furnace, with a calcination temperature of 700-900℃, a heating rate of 2-10℃ / min, and a calcination time of 60-180min.
7. The method for preparing an algal biochar-based catalyst according to claim 1, characterized in that, In step four: the pickling time is 4 to 12 hours, the temperature of the pickling oil bath is 60 to 100°C, and the acid used is 0.2 to 1M dilute sulfuric acid.
8. A wastewater treatment method, characterized in that, The iron and nitrogen co-modified Undaria biochar-based composite catalyst prepared by the method of preparing an algae biochar-based catalyst as described in any one of claims 1 to 7 is placed into the wastewater to be treated, ultrasonically dispersed, stirred for 10 to 30 minutes, and after reaching adsorption equilibrium, persulfate is added to start the reaction. The reaction temperature is 10 to 30°C and the reaction time is 1 to 60 minutes.
9. A wastewater treatment method according to claim 8, characterized in that, The mass ratio of the algal biochar-based catalyst to persulfate is 1:5 to 100.