Preparation method and application of nano-modified micro-electrolysis filler based on self-regeneration technology

Abstract

The invention discloses a preparation method and application of a nano-modified micro-electrolysis filler based on a self-regeneration technology, and belongs to the technical field of water pollution treatment. The method comprises the steps of iron-carbon matrix pretreatment, nano material loading, self-regeneration functional layer coating, filler forming, high-temperature activation and the like, it is ensured that the filler has efficient and stable reaction performance, the filler is filled according to the volume ratio of 30%, the hydraulic retention time is controlled to be 2-4 h, the removal rates of COD, ammonia nitrogen, total phosphorus and heavy metal ions can reach 90%, 85%, 80% and 95% or above respectively, and the method is suitable for industrial production. In the running process of the filler, a weak acid solution with the pH value of 5 is introduced every 30 days, and the self-regeneration function is activated. By optimizing the material modification and self-regeneration mechanism, the problems that a traditional micro-electrolysis filler is prone to passivation, high in decontamination capability attenuation speed and high in maintenance cost are solved, and the micro-electrolysis filler is suitable for lake entrance ecological interception engineering under the complex water quality condition and has the advantages of being efficient, stable and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of water pollution control, and particularly to a preparation method and application of a nano-modified micro-electrolysis filler based on self-regeneration technology. Background Art

[0002] The lake inlet, as the confluence of a river and a lake, is a key node for intercepting land-based pollutants and protecting the water ecological safety of the lake. With the rapid development of industry and agriculture and the acceleration of urbanization, a large amount of industrial wastewater, agricultural non-point source pollution, and domestic sewage are discharged into the river and finally flow into the lake, resulting in increasingly serious environmental problems such as lake eutrophication and water quality deterioration. As an effective pollution control means, the ecological interception technology at the lake inlet intercepts and purifies pollutants in the incoming lake water through engineering measures such as constructing artificial wetlands and ecological filter dams, utilizing the synergistic effects of physics, chemistry, and biology. Among them, the micro-electrolysis technology, as an efficient and low-cost water treatment technology, shows good application prospects in the ecological interception project at the lake inlet.

[0003] The micro-electrolysis technology utilizes the micro-galvanic cells formed by iron-carbon fillers in the solution to effectively remove organic pollutants, heavy metal ions, etc. in the water body through oxidation-reduction, electrocoagulation, adsorption, etc. However, traditional micro-electrolysis fillers still have the following problems in practical applications: First, the surface of the filler is prone to passivation, resulting in a decrease in reaction activity and a reduction in decontamination efficiency; second, the service life of the filler is short, and it needs to be frequently replaced, increasing the operating cost; third, the selective adsorption ability of the filler for pollutants is limited, and it is difficult to cope with complex and changing water quality conditions. In addition, the water quality at the lake inlet fluctuates greatly due to factors such as seasons and rainfall, and traditional micro-electrolysis fillers are difficult to adapt to this dynamic change, restricting their application effects in practical projects.

[0004] In recent years, the nano-modification technology has provided new ideas for improving the performance of micro-electrolysis fillers. By loading nano-materials on the surface of iron-carbon fillers, the specific surface area and reaction activity of the fillers can be significantly increased, and their adsorption and degradation abilities for pollutants can be enhanced. However, the existing nano-modified micro-electrolysis fillers still face problems such as easy shedding of nano-materials, unstable modification effects, and lack of self-regeneration function, making it difficult to achieve long-term and efficient operation of the fillers. Developing a nano-modified micro-electrolysis filler based on self-regeneration technology to solve the problems of easy passivation, short service life, and low decontamination efficiency of traditional fillers is of great significance for improving the engineering application effects of the ecological interception technology at the lake inlet. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method and application of nano-modified micro-electrolysis fillers based on self-regeneration technology, which are used to efficiently remove organic pollutants, heavy metal ions, etc. in water bodies, have self-regeneration functions, can effectively extend the service life of the fillers, reduce operation and maintenance costs, and provide reliable technical support for the ecological interception project at the lake inlet to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A preparation method of nano-modified micro-electrolysis fillers based on self-regeneration technology, including the following steps:

[0007] Mix high-purity iron filings and activated carbon in a mass ratio of 3:1, place them in a 10% dilute hydrochloric acid solution for pickling for 30 minutes to remove surface oxides and impurities; then transfer the pickled mixture to a 5% sodium hydroxide solution for alkali washing for 20 minutes to neutralize the residual acid solution and further remove impurities; then repeatedly rinse the mixture with deionized water until neutral, and dry it for standby; then immerse the pretreated iron-carbon matrix in a mixed dispersion of nano-titanium dioxide and nano-zero-valent iron, and the concentration of nano-materials in the dispersion is 1.5 g / L; use ultrasonic treatment for 30 minutes to uniformly disperse the nano-materials, and then mechanically stir for 2 hours to ensure that the nano-materials are fully loaded on the surface of the iron-carbon matrix to form a nano-modified layer with a high specific surface area; then immerse the iron-carbon matrix loaded with the nano-modified layer in a polymer solution composed of polyvinyl alcohol and chitosan mixed in a mass ratio of 2:1, impregnate for 1 hour, and dry at 60°C to form a pH-responsive self-repairing film; this film can release active substances under weakly acidic conditions to repair the passivation layer on the surface of the filler and restore its reaction activity, thereby extending the service life of the filler; finally, press the treated iron-carbon matrix into spherical fillers with a diameter of 5 mm, calcine at a high temperature of 500°C for 2 hours under nitrogen protection, and activate in 10% dilute sulfuric acid for 30 minutes to obtain nano-modified micro-electrolysis fillers.

[0008] Furthermore, the mass ratio of iron filings to activated carbon in the iron-carbon matrix can be adjusted to 2:1 to 4:1 according to the actual water quality conditions to meet the removal requirements of different pollutants.

[0009] Furthermore, the mass ratio of nano-TiO2 to nZVI in the nano-modified layer is 1:1 to 1:2 to optimize the synergistic removal effect of the filler on organic pollutants and heavy metal ions.

[0010] Furthermore, the mass ratio of PVA to CS in the self-regeneration functional layer is 2:1 to 3:1 to ensure that the polymer film can effectively release active substances under weakly acidic conditions and repair the passivation layer on the surface of the filler.

[0011] Further, during the molding process of the filler, the pressure for compression molding is 10 - 20 MPa to ensure that the mechanical strength and porosity of the filler meet the requirements of engineering applications.

[0012] Further, during the activation process of the filler, the concentration of dilute sulfuric acid is 5% - 15%, and the activation time is 20 - 40 minutes to optimize the reaction activity on the surface of the filler.

[0013] The present invention provides another technical solution, an application of a nano - modified micro - electrolysis filler based on self - regeneration technology. The prepared nano - modified micro - electrolysis filler is filled at a volume ratio of 30%, the height of the filler layer is 1.5 m, and the HRT is controlled within 2 - 4 hours; according to the dynamic changes in the water quality at the lake inlet, the height of the filler layer and HRT are adjusted to achieve efficient removal of COD, ammonia nitrogen, total phosphorus, and heavy metal ions; during the operation of the filler, a weak acidic solution with a pH value of 5 is introduced every 30 days to activate the self - regeneration functional layer, repair the passivation layer on the surface of the filler, and restore its reaction activity.

[0014] Further, during the maintenance process of the filler, by regularly monitoring the water quality of the effluent from the filler layer, the decontamination efficiency and reaction activity of the filler are evaluated. When the decontamination efficiency drops to 80% of the initial value, the self - regeneration function is activated; if the efficiency is still lower than 80% after self - regeneration, the filler needs to be replaced.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] Through the synergistic effect of nano-modification and the self-regeneration functional layer, the present invention significantly improves the decontamination efficiency, service life, and dynamic water quality adaptability of the filler. The introduction of the nano-modification layer greatly increases the specific surface area and reaction activity of the filler, significantly enhancing its adsorption and degradation capabilities for organic pollutants and heavy metal ions, and improving the decontamination efficiency by more than 30%. The self-regeneration functional layer can release active substances under weakly acidic conditions to repair the passivation layer on the surface of the filler, restore its reaction activity, extend the service life of the filler by more than 50%, and reduce the operation and maintenance costs. In addition, the filler has excellent adaptability to the complex and variable water quality at the lake inlet, and can automatically adjust its reaction activity according to water quality changes to ensure high-efficiency decontamination under different water quality conditions. Moreover, the filler preparation process of the present invention is simple, low-cost, and easy to mass-produce and apply. By optimizing the pretreatment process of the iron-carbon matrix, the loading method of nano-materials, and the coating technology of the self-regeneration functional layer, the high efficiency and stability of the filler are ensured. At the same time, during the application process, the filling ratio and hydraulic retention time of the filler can be flexibly adjusted according to the actual water quality conditions to further optimize the decontamination effect. Its mechanical strength and porosity are strictly controlled to ensure its stability and durability during long-term operation. In addition, during the operation of the filler of the present invention, the self-regeneration function can be periodically activated to repair the surface passivation layer and restore the reaction activity, significantly reducing the replacement frequency and maintenance costs of the filler. By real-time monitoring the water quality of the effluent from the filler layer, the decontamination efficiency and reaction activity of the filler can be evaluated in a timely manner, and a scientific maintenance plan can be formulated to ensure the long-term stable operation of the ecological interception project. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the process flow chart of the preparation process of the micro-electrolysis filler of the present invention;

[0018] Figure 2 is the structural schematic diagram of the nano-modified filler of the present invention.

[0019] In the figure: 1. High-purity iron filings; 2. Activated carbon; 3. 10% dilute hydrochloric acid; 4. 5% sodium hydroxide solution; 5. Mixture; 6. Ionized water; 7. Nano-TiO2; 8. nZVI; 9. Nano-materials; 10. Nano-modification layer; 11. PVA; 12. CS; 13. Iron-carbon matrix; 14. Self-regeneration functional layer; 15. Spherical filler 15; 16. Nitrogen; 17. Filler; 18. 10% dilute sulfuric acid solution 19. Optimized filler; 20. Inlet water area; 21. Outlet water area; 22. Self-regeneration functional pores; 23. Water quality monitoring pores. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the protection scope of the present invention.

[0021] Please refer to Figure 1 , the embodiments of the present invention provide a preparation method of nano-modified micro-electrolysis filler based on self-regeneration technology, including the following steps: pretreatment of the iron-carbon matrix, loading of the nano-modified layer, coating of the self-regeneration functional layer, and shaping and activation of the filler. Among them:

[0022] The pretreatment of the iron-carbon matrix means mixing high-purity iron filings 1 and activated carbon 2 at a mass ratio of 3:1, placing them in a 10% dilute hydrochloric acid 3 solution for pickling for 30 minutes to remove surface oxides and impurities; then transferring the pickled mixture to a 5% sodium hydroxide solution 4 for alkali washing for 20 minutes to neutralize the residual acid solution and further remove impurities; then repeatedly rinsing the mixture 5 with deionized water 6 until neutral, and drying for standby.

[0023] The loading of the nano-modified layer means immersing the pretreated iron-carbon matrix in a mixed dispersion of nano-TiO₂ 7 and nZVI 8, and the concentration of the nano-materials in the dispersion is 1.5 g / L; using ultrasonic treatment for 30 minutes to uniformly disperse the nano-materials 9, and then mechanically stirring for 2 hours to ensure that the nano-materials are fully loaded on the surface of the iron-carbon matrix to form a nano-modified layer 10 with a high specific surface area.

[0024] The coating of the self-regeneration functional layer means immersing the iron-carbon matrix loaded with the nano-modified layer in a polymer solution formed by mixing PVA 11 and CS 12 at a mass ratio of 2:1 for an impregnation time of 1 hour; then drying the impregnated iron-carbon matrix 13 at 60 °C to form a self-regeneration functional layer 14 with self-repair ability.

[0025] The shaping and activation of the filler means pressing the treated iron-carbon matrix into spherical fillers 15 with a diameter of 5 mm, and the molding pressure is 10-20 MPa; then under the protection of nitrogen 16, calcining the spherical fillers at a high temperature of 500 °C for 2 hours to enhance the stability and reaction activity of the fillers 17; finally immersing the calcined fillers in a 10% dilute sulfuric acid solution 18 for activation for 30 minutes to further optimize the reaction activity on the surface of the fillers 19.

[0026] Please refer to Figure 2 , the structural schematic diagram of the nano-modified micro-electrolysis filler in the embodiments of the present invention shows the application method of the filler in the ecological interception project at the lake inlet. Among them:

[0027] When filling the packing, the prepared nano-modified micro-electrolysis packing 19 is filled into the reactor of the ecological interception project at a volume ratio of 30%, and the height of the packing layer is 1.5 m (adjusted according to the actual water quality). The packing layer is evenly distributed to ensure that the water flow can fully contact the surface of the packing, realizing efficient decontamination.

[0028] The water flow enters from the water inlet area 20 of the reactor and flows out from the water outlet area 21 after passing through the packing layer. During the process of flowing through the packing 19, the organic pollutants and heavy metal ions in the water body are adsorbed, degraded or reduced by the packing. The nano-modified layer and the self-regenerating functional layer on the surface of the packing work together to significantly improve the decontamination efficiency.

[0029] During the operation of the packing, a weak acidic solution with a pH value of 5 is injected into the self-regenerating functional holes 22 every 30 days to activate the self-regenerating functional layer, repair the passivation layer on the surface of the packing, and restore its reaction activity. This self-regenerating mechanism significantly extends the service life of the packing and reduces the operation and maintenance costs.

[0030] The water quality of the effluent from the packing layer is regularly monitored through the water quality monitoring holes 23 (such as COD, ammonia nitrogen, total phosphorus, heavy metal ion concentration, etc.) to evaluate the decontamination efficiency and reaction activity of the packing. When the decontamination efficiency drops to 80% of the initial value, the self-regenerating function is started; if the efficiency is still lower than 80% after self-regeneration, the packing needs to be replaced.

[0031] Practical application: An ecological interception project at the inlet of a lake is located at the inlet of a certain lake, mainly intercepting organic pollutants and heavy metal ions from upstream agricultural non-point source pollution and urban domestic sewage. The project uses the nano-modified micro-electrolysis packing of the present invention, with a designed height of the packing layer of 1.2 m, a packing filling volume ratio of 25%, and an HRT of 2.5 hours. During the operation of the project, the concentrations of COD, ammonia nitrogen, total phosphorus and heavy metal ions in the water quality at the lake inlet are 150 mg / L, 8 mg / L, 1.5 mg / L and 3 mg / L respectively. During the operation of the project, the effluent water quality is sampled and analyzed every 5 days to monitor the concentration changes of COD, ammonia nitrogen, total phosphorus and heavy metal ions (such as copper ions, zinc ions, lead ions, cadmium ions, etc.). After 30 days of operation, the effluent water quality is significantly improved, and the removal rates of COD, ammonia nitrogen, total phosphorus and heavy metal ions reach more than 90%, 85%, 80% and 95% respectively. At the same time, by regularly introducing a weak acidic solution with a pH value of 5, the self-regenerating function of the packing is activated, the passivation layer on the surface of the packing is repaired, and its reaction activity is restored, significantly extending the service life of the packing and reducing the operation and maintenance costs.

[0032] In summary, the nanostructured micro-electrolysis filler of the present invention has a novel structural design, a reasonable preparation process, high decontamination efficiency, long service life, and strong adaptability to dynamic water quality. By optimizing the pretreatment process of the iron-carbon matrix, the loading method of nanomaterials, and the coating technology of the self-regenerating functional layer, the efficiency and stability of the filler are ensured. At the same time, during the application process of the filler, the filling ratio and hydraulic retention time can be flexibly adjusted according to the actual water quality conditions to further optimize the decontamination effect. By regularly activating the self-regenerating function, the passivation layer on the surface of the filler is repaired, and its reaction activity is restored, significantly reducing the replacement frequency and maintenance cost of the filler, providing efficient, stable, and environmentally friendly technical support for the ecological interception project at the lake inlet under complex water quality conditions, and having broad application prospects and significant social and economic benefits.

[0033] The above has schematically described the present invention and its embodiments. This description is not restrictive, and only one of the embodiments of the present invention is shown in the drawings. The actual structure is not limited thereto. Therefore, if those of ordinary skill in the art are inspired by it and design similar structural modes and embodiments without creative efforts without departing from the purpose of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A preparation method of nano-modified micro-electrolysis filler based on self-regeneration technology, characterized in that: It includes the following steps: Mix high-purity iron filings (1) and activated carbon (2) at a mass ratio of 3:1, place them in a 10% dilute hydrochloric acid solution (3) for pickling for 30 minutes to remove surface oxides and impurities; then transfer the pickled mixture to a 5% sodium hydroxide solution (4) for alkali washing for 20 minutes to neutralize the residual acid solution and further remove impurities; then repeatedly rinse the mixture (5) with deionized water (6) until neutral, and dry it for standby; then immerse the pretreated iron-carbon matrix in a mixed dispersion of nano-titanium dioxide (7) and nano-zero-valent iron (8), and the concentration of nano-materials in the dispersion is 1.5 g / L; use ultrasonic treatment for 30 minutes to uniformly disperse the nano-materials (9), and then mechanically stir for 2 hours to ensure that the nano-materials are fully loaded on the surface of the iron-carbon matrix to form a nano-modified layer (10) with a high specific surface area; then immerse the iron-carbon matrix loaded with the nano-modified layer in a polymer solution formed by mixing polyvinyl alcohol (11) and chitosan (12) at a mass ratio of 2:1, and the polymer (13) after impregnation for 1 hour is dried at 60°C to form a pH-responsive self-healing membrane (14); this membrane can release active substances under weakly acidic conditions to repair the passivation layer on the surface of the filler and restore its reaction activity, thereby extending the service life of the filler; finally, press the treated iron-carbon matrix (15) into spherical fillers with a diameter of 5 mm, and calcine the material (17) at 500°C for 2 hours under the protection of nitrogen (16), and activate it in 10% dilute sulfuric acid (18) for 30 minutes to obtain nano-modified micro-electrolysis fillers (19).

2. The preparation method of a nano-modified micro-electrolysis filler based on self-regeneration technology according to claim 1, characterized in that: The mass ratio of iron filings (1) to activated carbon (2) in the iron-carbon matrix can be adjusted to 2:1 to 4:1 according to the actual water quality conditions to meet the removal requirements of different pollutants.

3. The preparation method of a nano-modified micro-electrolysis filler based on self-regeneration technology according to claim 1, characterized in that: The mass ratio of nano-TiO2 (7) to nZVI (8) in the nano-modified layer is 1:1 to 1:2 to optimize the synergistic removal effect of the filler on organic pollutants and heavy metal ions.

4. A preparation method of a nano-modified micro-electrolysis filler based on a self-regenerating technology according to claim 1, characterized in that: The mass ratio of PVA (11) to CS (12) in the self-regenerating functional layer is 2:1 to 3:1 to ensure that the polymer membrane can effectively release active substances under weakly acidic conditions and repair the passivation layer on the surface of the filler.

5. A preparation method of a nano-modified micro-electrolysis filler based on self-regeneration technology according to claim 1, characterized in that: During the molding process of the filler (15), the pressure for pressing and molding is 10-20 MPa to ensure that the mechanical strength and porosity of the filler meet the requirements of engineering applications.

6. The preparation method of a nano-modified micro-electrolysis filler based on self-regeneration technology according to claim 1, characterized in that: During the activation process of the filler, the concentration of dilute sulfuric acid (18) is 5%-15%, and the activation time is 20-40 minutes to optimize the reaction activity on the surface of the filler.

7. Application of a nano-modified micro-electrolysis filler based on self-regeneration technology, characterized in that: Load the prepared nano-modified micro-electrolysis fillers at a volume ratio of 30%, the height of the filler layer is 1.5 m, and the HRT is controlled at 2-4 hours; adjust the height of the filler layer and HRT according to the dynamic changes of the water quality at the lake inlet to achieve efficient removal of COD, ammonia nitrogen, total phosphorus and heavy metal ions; during the operation of the filler, a weakly acidic solution with a pH value of 5 is introduced every 30 days to activate the self-regenerating functional layer, repair the passivation layer on the surface of the filler, and restore its reaction activity.

8. The application of a nano-modified micro-electrolysis filler based on self-regeneration technology according to claim 7, characterized in that: During the maintenance of the packing (19), the water quality of the effluent from the packing layer is regularly monitored to evaluate the decontamination efficiency and reaction activity of the packing. When the decontamination efficiency drops to 80% of the initial value, the self-regeneration function is activated; if the efficiency is still lower than 80% after self-regeneration, the packing needs to be replaced.

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