Iron-carbon micro-electrolysis constructed wetland filler, preparation method and application thereof

Abstract

This invention discloses an iron-carbon micro-electrolysis constructed wetland filler, its preparation method, and its application, belonging to the field of environmental water treatment technology. The preparation method of the iron-carbon micro-electrolysis constructed wetland filler includes the following steps: using a bio-templating method, biomass powder is boiled in water to separate the solid and liquid phases. The filtrate is used as the bio-templating liquid and mixed evenly with dried solid powder, reduced iron powder, binder, and pore-forming agent. Then, granulation, drying, and carbonization are performed sequentially to prepare the iron-carbon micro-electrolysis constructed wetland filler. In other words, this invention uses a bio-templating method, utilizing the natural structure of the bio-template to achieve uniform dispersion of iron and carbon, avoiding agglomeration. This demonstrates significant advantages in improving wastewater treatment efficiency, enhancing material performance, and reducing environmental impact.

Description

Technical Field

[0001] This invention belongs to the field of environmental water treatment technology, and in particular relates to an iron-carbon micro-electrolysis artificial wetland filler, its preparation method and application. Background Technology

[0002] Antibiotics are widely used in medicine, agriculture, aquaculture, and livestock farming. Tetracyclines, quinolones, and sulfonamides are commonly found in aquaculture wastewater or aquaculture waters. However, antibiotics cannot be completely degraded and absorbed by organisms, exhibiting strong persistence. They often accumulate in the aquatic environment, threatening ecological security and human health through the food chain.

[0003] Therefore, developing green, efficient, and low-cost antibiotic removal technologies is of great value in alleviating water pollution. Currently, antibiotic removal methods include ozone oxidation, biodegradation, photodegradation, adsorption, and hydrolysis. However, these methods have high operating costs and cannot completely degrade and remove antibiotics. Constructed wetlands, due to their advantages of low cost, low energy consumption, convenient management, and significant ecological benefits, have been widely used in wastewater treatment. Constructed wetlands are near-natural ecosystems composed of substrates, plants, and microorganisms. Through the combined effects of plant absorption, substrate adsorption, and microbial degradation, antibiotics are removed.

[0004] As the core component of constructed wetlands, the substrate can not only remove pollutants from wastewater through adsorption, sedimentation, and filtration, but also provide a carrier and nutrients for plants and microorganisms. Selecting appropriate fillers can improve the wastewater treatment effect of constructed wetlands and reduce construction and maintenance costs.

[0005] In the Fe-C micro-electrolysis system based on iron and carbon, iron with a negative redox potential and carbon with a positive redox potential form a micro-galvanic cell. The numerous micro-current electric fields generated between the iron and carbon cells, along with the micro-electrolysis, produce a large number of active groups (Fe(II), H₂O₂, and [H]), which accelerate the oxidative degradation of antibiotics in wastewater. Simultaneously, the iron-carbon based material is porous and also exhibits a certain degree of adsorption in wastewater, achieving rapid and efficient treatment of antibiotic wastewater.

[0006] Current methods for preparing iron-carbon materials primarily involve first calcining biomass powder at high temperatures to produce biochar powder; then mixing the biochar powder with iron powder to form a shaped mixture, followed by another high-temperature calcination. This type of iron-carbon micro-electrolysis material preparation process is complex and energy-intensive. Furthermore, zero-valent iron agglomeration is prone to occur during the preparation process, leading to uneven distribution. Additionally, the internal structure of the filler particles collapses during high-temperature calcination, resulting in reduced porosity and loss of the original porous structure, thus affecting the application performance of the iron-carbon micro-electrolysis material. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes an iron-carbon micro-electrolysis artificial wetland filler, its preparation method, and its application.

[0008] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention: A method for preparing an iron-carbon micro-electrolysis artificial wetland filler includes the following steps: S1. Using the biotemplate method, biomass powder is boiled in water to separate solids and liquids. The filtrate is used as the biotemplate liquid. The solid after solid-liquid separation is dried and sieved to obtain solid powder. S2. The solid powder, reduced iron powder, binder and pore-forming agent are mixed evenly to obtain a mixture. The filtrate is added to the mixture and stirred evenly. Then, granulation, drying and carbonization are carried out in sequence to prepare the iron-carbon micro-electrolysis artificial wetland filler.

[0009] Optionally, the preparation process of the biomass powder is as follows: Artificial wetland plants were selected as biomass raw materials. The wetland plants were cut into 4-5cm sections, washed with deionized water, dried at 105℃, crushed, and passed through a 100-mesh sieve to obtain biomass powder.

[0010] Optionally, the ratio of biomass powder to water is 1g:5mL to 1g:20mL; the boiling process takes 0.5 to 1 hour.

[0011] Optionally, the temperature during the drying process in steps S1 and S2 is 105°C.

[0012] Optionally, the mass ratio of the solid powder to the reduced iron powder is (3:1) to (1:3).

[0013] Optionally, the amount of the binder is 15% to 40% of the total mass of the solid powder and reduced iron powder.

[0014] Furthermore, the adhesive is bentonite.

[0015] Optionally, the amount of the pore-forming agent is 1.5% to 4% of the total mass of the solid powder and reduced iron powder.

[0016] Furthermore, the pore-forming agent is sodium bicarbonate.

[0017] Optionally, the liquid-to-solid ratio of the filtrate is 1.5 mL : (1-2.5) g; wherein the liquid-to-solid ratio is the ratio of the amount of mixture (i.e., solid powder + reduced iron powder + bentonite + sodium bicarbonate) to the amount of filtrate.

[0018] Optionally, the diameter of the particles obtained by the granulation process is 4cm-16cm.

[0019] Optionally, the conditions during the carbonization process are as follows: heating to 600℃-700℃ at a heating rate of 5℃ / min, and then carbonizing at this temperature for 2 hours.

[0020] The second technical solution of this invention: An iron-carbon micro-electrolysis artificial wetland filler is prepared by the above-mentioned preparation method.

[0021] The third technical solution of this invention: The above-mentioned iron-carbon micro-electrolysis constructed wetland packing material is used in the field of removing antibiotics from wastewater.

[0022] Optionally, the antibiotics include tetracycline hydrochloride (TC), norfloxacin (NOR), and sulfadiazine (SD).

[0023] Optionally, the concentration of antibiotics in the wastewater is 50-250 mg / L; In the application described, the amount of iron-carbon micro-electrolysis constructed wetland filler added to the wastewater is 1 g / 200 mL.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects: (1) This invention selects common plants in artificial wetlands as biomass raw materials, realizing the resource utilization of wetland plants at low cost.

[0025] (2) The present invention directly uses biomass powder to prepare iron-carbon micro-electrolysis artificial wetland filler, which is simple to operate and consumes less energy in the preparation process.

[0026] (3) The present invention adopts the biological template method, which utilizes the natural structure of the biological template to achieve uniform dispersion of iron and carbon, avoid agglomeration, and improve material performance.

[0027] (4) The present invention adds pore-forming agent and binder, which helps to improve the structural stability of the material and prevent structural collapse; the mixed filler forms pores after the pore-forming agent is added and decomposed, which increases the specific surface area of ​​the material and improves the adsorption and catalytic performance.

[0028] (5) The iron-carbon micro-electrolysis artificial wetland filler prepared by the present invention not only has good adsorption and retention capacity for antibiotics, but also provides a growth attachment surface for artificial wetland microorganisms. Among them, carbon can provide carbon source for microorganisms, and iron can act as electron donor or acceptor to promote the electron transfer process of microorganisms, enhance their metabolic activity, and promote the degradation of pollutants. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The isothermal adsorption curves of tetracycline hydrochloride (TC) on the fillers prepared in Examples 1-3 and Comparative Examples 1-2 of this invention are shown. Figure 2 The isothermal adsorption curves of norfloxacin (NOR) on the packing materials prepared in Examples 1-3 and Comparative Examples 1-2 of this invention are shown. Figure 3 The isothermal adsorption curves of sulfadiazine (SD) on the packing materials prepared in Examples 1-3 and Comparative Examples 1-2 of this invention are shown. Figure 4 Electron micrographs of the packing materials prepared in Comparative Example 1(a), Example 2(b), Example 3(c) and Example 1(d). Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] This invention provides a method for preparing iron-carbon micro-electrolysis artificial wetland filler, comprising the following steps: (1) Cleaning of biomass raw materials: Select common artificial wetland plants as biomass raw materials, cut the wetland plants into 4-5cm sections with a cleaver, wash them with deionized water, and dry them at 105℃ for later use. (2) Biomass raw material pretreatment: The dried wetland plants are crushed and passed through a 100-mesh sieve to obtain biomass powder; (3) Weigh a certain amount of biomass powder, boil it in boiling water for 0.5-1h, and then separate the solid and liquid after cooling; collect the filtrate for use as a biological template solution. (4) The separated solids are dried at 105°C and then passed through a 100-mesh sieve to obtain solid powder for later use. (5) Weigh a certain mass of the solid powder processed in step (4), and mix the reduced iron powder, bentonite and sodium bicarbonate to obtain a mixture; The mass ratio of solid powder to reduced iron powder is 3:1 to 1:3; bentonite is used as a binder, accounting for 15% to 40% of the total mass of solid powder and reduced iron powder; sodium bicarbonate is used as a pore-forming agent, accounting for 1.5% to 4% of the total mass of solid powder and iron powder.

[0036] (6) Add biological template liquid (liquid-solid ratio of 1.5 mL: (1-2.5) g) to the mixture obtained in step (5) according to a certain solid-liquid ratio to form a mixture with a suitable viscosity, and stir in a mixer for 0.5-1 h; (7) The mixture obtained by stirring in step (6) is prepared into spherical particles by a granulator with a particle diameter of 4cm-16cm. (8) Place the prepared wet spherical filler in a drying oven at 105℃ and dry for 6-8 hours; (9) The dried spheres were placed in a nitrogen atmosphere tubular furnace for carbonization. The parameters were set as follows: heating rate 5℃ / min, heating to 600℃-700℃, and then carbonizing at this temperature for 2 hours. The carbonization process caused the biomass raw material to pyrolyze to obtain gas and coke products. The coke products and iron elements combined, with the coke products acting as a carrier and the iron elements loaded on the coke products. After natural cooling to room temperature, iron-carbon micro-electrolysis artificial wetland filler was obtained.

[0037] The present invention also provides an iron-carbon micro-electrolysis packing material prepared by the above preparation method, and applies the iron-carbon micro-electrolysis artificial wetland packing material to remove antibiotic wastewater.

[0038] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0039] All raw materials used in this invention were purchased from the market.

[0040] The technical solution of the present invention will be further illustrated by the following embodiments.

[0041] Example 1 A method for preparing an iron-carbon micro-electrolysis artificial wetland filler includes the following steps: (1) Cut the emergent plants of the canna wetland into small sections of about 5cm with a cleaver, wash them with deionized water, and dry them in an oven at 105℃; (2) Crush the dried canna plant and pass it through a 100-mesh sieve to obtain canna plant powder; (3) Weigh out the canna plant powder and boil it in boiling water for 0.5 hours. The ratio of canna plant powder to boiling water is 100g:500mL. Then cool and separate the solid and liquid. Collect the filtrate for use as a biological template solution. (4) The separated solids are dried at 105°C and then passed through a 100-mesh sieve to obtain solid canna powder (solid powder) for later use. (5) Accurately weigh 75g of canna powder (solid powder), 25g of reduced iron powder, 30g of bentonite and 3g of sodium bicarbonate, and measure 150mL of biological template liquid, place it in a mixer and stir for 0.5h to obtain a mixture; (6) The mixture is granulated into spheres with a diameter of 8 mm using a granulator; (7) Place the prepared wet spherical filler in a drying oven at 105℃ and dry for 8 hours; (8) The dried particles were then placed in a nitrogen atmosphere tube furnace for carbonization. The parameters were set as follows: heating rate 5℃ / min, heating to 700℃, and then carbonization for 2h. The particles were then allowed to cool naturally to room temperature to obtain an iron-carbon micro-electrolysis filler (Fe / 3BC).

[0042] Example 2 The difference from Example 1 is that in step (4), the amount of canna lily powder is 100g and the amount of reduced iron powder is 100g. Other preparation processes and conditions are the same as in Example 1. Example 2 prepared an iron-carbon microelectrolysis filler (Fe / BC).

[0043] Example 3 The difference from Example 1 is that in step (4), the amount of canna lily powder is 100g and the amount of reduced iron powder is 50g. Other preparation processes and conditions are the same as in Example 1. Example 3 prepared an iron-carbon microelectrolysis filler (Fe / 2BC).

[0044] Comparative Example 1 The difference from Example 1 is that in step (5), the iron powder is replaced by solid powder, specifically: (5) Accurately weigh 100g of canna powder, 30g of bentonite and 3g of sodium bicarbonate, and measure 150mL of biological template solution, place them in a mixer and stir for 0.5h to obtain a mixture; The other preparation processes and conditions are the same as in Example 1. Comparative Example 1 prepared an iron-free carbonaceous filler (BC).

[0045] Comparative Example 2 Commercially available activated carbon granules were used as a control group.

[0046] Effect verification The materials prepared in Examples 1-3, as well as Comparative Examples 1 and 2, were used to verify the removal effects of a series of concentrations of antibiotics (tetracycline hydrochloride, norfloxacin, and sulfadiazine).

[0047] Example 1 (1) Weigh a certain mass of tetracycline hydrochloride and prepare tetracycline hydrochloride (TC) solutions with different initial concentrations.

[0048] (2) Measure 200 mL of tetracycline hydrochloride solution of various concentrations and place them in 250 mL stoppered conical flasks.

[0049] (3) Add 1g BC or 1g Fe / 3BC or 1g Fe / 2BC or 1g Fe / BC or 1g control (commercial activated carbon granules) to the bottle respectively, and put them into the stoppered conical bottle.

[0050] (4) Place in a constant temperature shaker at 25℃ and 150 rpm for 24 hours.

[0051] (5) Filter with a 0.22 μm filter membrane, determine the tetracycline hydrochloride content in the filtrate, and calculate the adsorption of tetracycline hydrochloride by BC, Fe / 3BC, Fe / 2BC, Fe / BC and control.

[0052] Example 2 (1) Weigh a certain mass of norfloxacin and prepare norfloxacin (NOR) solutions with different initial concentrations.

[0053] (2) Measure 200 mL of each series of norfloxacin solutions and place them in 250 mL stoppered conical flasks.

[0054] (3) Add 1g BC or 1g Fe / 3BC or 1g Fe / 2BC or 1g Fe / BC or 1g control (commercial activated carbon granules) to the bottle respectively, and put them into the stoppered conical bottle.

[0055] (4) Place in a constant temperature shaker at 25℃ and 150 rpm for 24 hours.

[0056] (5) Filter with a 0.22 μm filter membrane, determine the norfloxacin content in the filtrate, and calculate the adsorption capacity of BC, Fe / 3BC, Fe / 2BC, Fe / BC and control for norfloxacin.

[0057] Example 3 (1) Weigh a certain mass of sulfadiazine and prepare sulfadiazine (SD) solutions with different initial concentrations.

[0058] (2) Measure 200 mL of each concentration of sulfadiazine solution and place them in a 250 mL stoppered conical flask.

[0059] (3) Add 1gBC or 1gFe / 3BC or 1gFe / 2BC or 1gFe / BC or 1gcontrol (commercial activated carbon granules) to the bottle respectively, and put them into the stoppered conical bottle.

[0060] (4) Place in a constant temperature shaker at 25℃ and 150 rpm for 24 hours.

[0061] (5) Filter with a 0.22 μm filter membrane, determine the sulfadiazine content in the filtrate, and calculate the adsorption amount of sulfadiazine by BC, Fe / 3BC, Fe / 2BC, Fe / BC and control.

[0062] The experimental data from Examples 1-3 were fitted using the Freundich model, Langmuir-Freundich model, and Dubinin-Radushkviech model (as shown in Tables 1-3). The R-values ​​of the three models were compared. 2 The values ​​indicate that the Langmuir-Frundich model has a higher fitting degree, suggesting that the adsorption of the three antibiotics by the iron-carbon micro-electrolysis filler involves both monolayer and multilayer adsorption.

[0063] Table 1 Table 2 Table 3 Figures 1-3Isothermal adsorption curves of tetracycline hydrochloride (TC), norfloxacin (NOR), and sulfadiazine (SD) prepared by the packing materials in Examples 1-3, Comparative Examples 1 and 2 of this invention are shown. It can be seen that among the five packing materials, Fe / 2BC (Example 3) has the best adsorption effect on antibiotics. According to the model fitting results, the maximum adsorption capacities for tetracycline hydrochloride (TC), norfloxacin (NOR), and sulfadiazine (SD) are 7.1845, 6.6187, and 8.2949 mg / g, respectively. Control (Comparative Example 2) has the worst adsorption effect. Compared with Control, Fe / 2BC increased the maximum adsorption capacity for the three antibiotics by 345.55%, 538.32%, and 172.33%, respectively. The adsorption experiment results demonstrate that the iron-carbon micro-electrolysis constructed wetland packing material prepared in this invention has excellent adsorption performance for antibiotics and can effectively improve the removal capacity of antibiotics when used in constructed wetlands.

[0064] Figure 4 The images show electron microscope (EM) images of the fillers prepared in Comparative Example 1(a), Example 2(b), Example 3(c) and Example 1(d). As can be seen from the images, the fillers prepared in Examples 1-3 of the present invention achieve uniform dispersion of iron and carbon in the microstructure compared with Comparative Example 1, thus avoiding agglomeration.

[0065] In summary, on the one hand, the porous structure of iron-carbon packing can adsorb antibiotics in wastewater through physical interactions such as van der Waals forces and electrostatic interactions; on the other hand, its surface active sites (such as oxygen-containing functional groups) can form chemical bonds with antibiotics, enhancing the adsorption effect. Therefore, the addition of iron-carbon packing, introducing an Fe-C micro-electrolysis system, and the addition of iron provide Fe to the constructed wetland... 2+ Electron donor and Fe 3+ Electron acceptors enhance microbial activity, and microelectrolysis can also generate a large number of active groups (·O2). - (H2O2, -OH). Therefore, the packing material prepared in this invention can improve the adsorption and retention performance of antibiotics, enhance microbial activity, strengthen chemical oxidation, and enhance the removal capacity of constructed wetlands for antibiotics from multiple aspects.

[0066] Furthermore, this invention not only enhances the ability of constructed wetlands to remove antibiotics, but also realizes the resource utilization of wetland plants, thus expanding the application scope of constructed wetlands.

[0067] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an iron-carbon micro-electrolysis artificial wetland filler, characterized in that, Includes the following steps: S1. Using the biotemplate method, biomass powder is boiled in water to separate solids and liquids. The filtrate is used as the biotemplate liquid. The solid after solid-liquid separation is dried and sieved to obtain solid powder. S2. The solid powder is mixed evenly with reduced iron powder, binder and pore-forming agent to obtain a mixture. The filtrate is added to the mixture and stirred evenly. The viscosity is adjusted by controlling the liquid-solid ratio of the filtrate to the mixture. Then, granulation, drying and carbonization are carried out in sequence to prepare the iron-carbon micro-electrolysis artificial wetland filler. The ratio of biomass powder to water is 1g:(5-20)mL; The liquid-to-solid ratio of the filtrate to the mixture is 1.5 mL : (1-2.5) g.

2. The method for preparing an iron-carbon micro-electrolysis artificial wetland filler according to claim 1, characterized in that, The boiling process takes 0.5 to 1 hour.

3. The method for preparing an iron-carbon micro-electrolysis artificial wetland filler according to claim 1, characterized in that, The temperature during the drying process described in steps S1 and S2 is 105°C.

4. The method for preparing an iron-carbon micro-electrolysis artificial wetland filler according to claim 1, characterized in that, The mass ratio of the solid powder to the reduced iron powder is (3:1) to (1:3).

5. The method for preparing an iron-carbon micro-electrolysis artificial wetland filler according to claim 1, characterized in that, The amount of the binder is 15% to 40% of the total mass of the solid powder and reduced iron powder.

6. The method for preparing an iron-carbon micro-electrolysis artificial wetland filler according to claim 1, characterized in that, The amount of the pore-forming agent is 1.5% to 4% of the total mass of the solid powder and reduced iron powder.

7. The method for preparing an iron-carbon micro-electrolysis artificial wetland filler according to claim 1, characterized in that, The conditions for the carbonization process are as follows: the temperature is increased to 600℃-700℃ at a heating rate of 5℃ / min, and then carbonized at this temperature for 2 hours.

8. A type of iron-carbon micro-electrolysis artificial wetland filler, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

9. The application of the iron-carbon micro-electrolysis constructed wetland filler as described in claim 8 in the field of removing antibiotics from wastewater.

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