A composite slow-release material for groundwater remediation and a preparation process thereof
By combining the composite oxidant and self-Fenton system in the composite slow-release material with the action of microorganisms, the problem of low groundwater remediation efficiency in existing technologies has been solved, and a long-term and stable pollutant degradation effect has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF GEOGRAPHY HENAN ACAD OF SCI
- Filing Date
- 2025-03-12
- Publication Date
- 2026-07-21
AI Technical Summary
Among existing groundwater remediation technologies, activated carbon adsorption has limited adsorption capacity, chemical oxidation may generate secondary pollution and is costly, and bioremediation technology is inefficient and difficult to effectively treat certain pollutants.
The composite slow-release material, comprising a composite oxidant, an inner wall material, and an outer wall material, slowly releases active oxygen to activate indigenous microbial communities. Combined with mesoporous titanium dioxide and iron-based complexes, it forms a self-Fenton system that synergistically degrades pollutants through microorganisms.
It achieves long-lasting oxidative degradation of pollutants, promotes microbial growth, improves the efficiency and stability of groundwater remediation, and provides a lasting pollutant removal effect.
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Abstract
Description
Technical Field
[0001] This application relates to the field of groundwater remediation materials technology, and in particular to a composite slow-release material for groundwater remediation and its preparation process. Background Technology
[0002] Groundwater remediation is a crucial task in environmental protection. With rapid industrialization and the continuous expansion of human activities, groundwater pollution has become increasingly severe, threatening not only human health but also directly impacting the balance of ecosystems. To address this issue, scientists are constantly developing new technologies to improve the efficiency and sustainability of groundwater remediation. Among these, composite slow-release materials, with their outstanding performance in pollutant capture and degradation, have gradually become a research hotspot.
[0003] Existing groundwater remediation technologies typically employ a variety of methods, including activated carbon adsorption, chemical oxidation, and bioremediation. Activated carbon adsorption relies on the microporous structure of activated carbon to adsorb pollutants in the water. Chemical oxidation uses oxidants to oxidize and decompose pollutants, thus achieving purification. Furthermore, bioremediation utilizes the metabolism of microorganisms to degrade pollutants, thereby purifying groundwater.
[0004] However, the aforementioned existing technologies each have their own shortcomings. For example, activated carbon adsorption may have limited adsorption capacity and difficulty in removing certain recalcitrant pollutants; chemical oxidation may generate secondary pollution and is relatively expensive; and while bioremediation is environmentally friendly, it is inefficient in treating certain specific pollutants. Therefore, it is necessary to provide a novel composite slow-release material to address the technical challenges of groundwater remediation. Summary of the Invention
[0005] To improve the effectiveness of groundwater remediation, this application provides a composite slow-release material for groundwater remediation and its preparation process.
[0006] The technical solution provided in this application for a composite slow-release material for groundwater remediation and its preparation process is as follows:
[0007] Firstly, this application provides a composite slow-release material for groundwater remediation, employing the following technical solution:
[0008] A composite slow-release material for groundwater remediation, the raw materials for which are prepared include the following components in parts by weight:
[0009] 20-40 parts of compound oxidant
[0010] 30-50 parts of inner wall material
[0011] 10-20 servings of glucose
[0012] The outer wall material consists of 40-60 parts of Fenton mesoporous titanium dioxide and 5-15 parts of other materials.
[0013] The composite oxidant can slowly release active oxygen to oxidize and degrade pollutants in groundwater, activate indigenous microorganisms in situ, and promote the metabolism of pollutants by the microorganisms. The inner wall material encapsulates the composite oxidant, slowing down its decomposition rate and enabling the composite slow-release material to provide long-term oxidative degradation capabilities. Glucose can serve as a carbon source to provide energy for the indigenous microorganisms, promoting their metabolic growth and working synergistically with the composite oxidant to enhance the microorganisms' ability to metabolize pollutants. The outer wall material combines self-Fenton mesoporous titanium dioxide and glucose with the composite oxidant encapsulated in the inner wall material, so that the entire system, while providing a barrier, can also enable the composite oxidant to long-term activate the self-Fenton system for pollutant degradation, working synergistically with the indigenous microorganisms to enhance the groundwater remediation capacity.
[0014] Preferably, the raw materials for preparing the self-Fenton mesoporous titanium dioxide include mesoporous titanium dioxide bulk and iron-based complex.
[0015] Mesoporous titanium dioxide possesses a large specific surface area and abundant pore structure, enabling it to adsorb pollutant molecules and bring them close to active sites. Simultaneously, mesoporous titanium dioxide acts as a stable carrier for iron-based complexes, promoting their uniform dispersion on its surface and enhancing the stability of the Fenton system. Titanium dioxide itself also exhibits good catalytic activity, enhancing the Fenton reaction's ability to degrade pollutants and improving degradation efficiency. Iron-based complexes can undergo the Fenton reaction, generating active free radicals that enhance the ability of composite oxidants to degrade pollutants. The hydroxyl radicals generated from the Fenton system can directly oxidize and decompose pollutants. After being activated by composite oxidants, they synergistically break down large organic molecules into smaller molecules, serving as a nutrient source for indigenous microbial communities, promoting their growth and metabolism. This, in turn, works with indigenous microbial communities to degrade pollutants in groundwater, improving the durability and stability of the remediation effect.
[0016] Preferably, the iron-based complex includes an ethylenediaminetetraacetic acid iron complex.
[0017] The iron ions in the EDTA iron complex can trigger the Fenton reaction through the peroxides released by the composite oxidant encapsulated in the inner wall material, continuously generating highly oxidizing free radicals that attack various organic pollutants in groundwater, decomposing them into small molecules, thereby effectively improving the degradation efficiency of pollutants. These small molecule decomposition products can serve as nutrients for indigenous microbial communities, promoting their growth and reproduction and enhancing their ability to degrade pollutants. At the same time, the indigenous microbial communities alter the physicochemical properties of the local environment during metabolism, allowing the EDTA iron complex to maintain its activity and promote the continuous progress of the Fenton reaction. The synergistic effect of these two factors can effectively improve the comprehensiveness and durability of the remediation effect.
[0018] Preferably, the composite oxidant includes calcium peroxide and sodium persulfate.
[0019] Calcium peroxide slowly releases hydrogen peroxide in water, while sodium persulfate is a strong oxidant that can decompose to produce sulfate free radicals with strong oxidizing properties. The two work synergistically to continuously provide oxidation capacity, effectively degrading various organic pollutants in groundwater, including recalcitrant organic matter, breaking them down into harmless or low-harm small molecules. The long-term oxygen release can promote the growth of microorganisms, thereby working synergistically with the indigenous microbial community to improve the degradation efficiency of pollutants and thus enhance the remediation effect.
[0020] Preferably, the inner wall material comprises chitosan, polyvinyl alcohol, and a crosslinking agent.
[0021] Chitosan possesses excellent biocompatibility and adsorption properties, enabling it to interact with pollutants and slow down the release rate of calcium peroxide and sodium persulfate in the composite oxidant. Polyvinyl alcohol provides the wall material with flexibility and certain barrier properties, further regulating the release rate of the oxidant and allowing it to stably release oxygen over a longer period. The crosslinking agent connects chitosan and polyvinyl alcohol to form a stable three-dimensional network structure, enhancing the mechanical strength and stability of the wall material and effectively preventing premature cracking that would lead to a large premature release of the oxidant. This provides a long-lasting oxidizing environment for groundwater remediation, continuously degrading pollutants in groundwater and significantly improving the material's long-term degradation capacity, thus contributing to a more durable and stable groundwater remediation effect.
[0022] Preferably, the mass ratio of chitosan, polyvinyl alcohol and crosslinking agent is (3-5):(5-7):0.3.
[0023] The inner wall material prepared according to the above mass ratio has good stability and pore structure, which can effectively improve the repair effect of the composite sustained-release material.
[0024] Preferably, the crosslinking agent includes one of genipin and maleic anhydride.
[0025] Genipin and maleic anhydride can chemically react with chitosan and polyvinyl alcohol to form a stable three-dimensional cross-linked network structure, which improves the mechanical strength of the inner wall material, effectively prevents premature leakage of the composite oxidant, and provides a stable oxidizing environment for groundwater remediation. The network structure formed by the cross-linking of genipin or maleic anhydride has specific porosity and permeability. By controlling the amount of cross-linking agent and reaction conditions, the pore size and distribution of the wall material can be regulated, thereby effectively controlling the release rate of the oxidant. Genipin has good biocompatibility, and the wall material structure formed by its cross-linking can provide a suitable environment for the attachment and growth of microorganisms. Maleic anhydride is also well compatible with the groundwater environment, promoting the effective remediation role of the composite slow-release material in complex and variable groundwater environments.
[0026] Preferably, the outer wall material comprises starch, peptone, and carbodiimide.
[0027] Starch possesses excellent film-forming and adsorption properties, enabling it to form a protective film on the outer layer of the material, effectively coating the components in the composite slow-release material while adsorbing and retaining pollutants. Peptone, rich in various amino acids, adds abundant active groups and nutrients to the outer wall material, improving its biocompatibility and facilitating interaction with microorganisms in the groundwater environment, promoting their attachment and growth on the wall material surface. Carbodiimide can chemically link starch and peptone molecules to form a three-dimensional network structure, significantly enhancing the mechanical strength and stability of the outer wall material. This prevents the wall material from cracking or degrading in the groundwater environment due to water flow impact, physical pressure, or chemical erosion, thus allowing the composite slow-release material to function stably for a long time, improving the removal efficiency of pollutants and the durability of the remediation effect.
[0028] Preferably, the mass ratio of starch, peptone and carbodiimide is (6-7):(2-3):1.
[0029] The outer wall material prepared according to the above mass ratio has good stability and adsorption performance, can provide nutrients for microorganisms, and synergistically improves the removal efficiency of pollutants.
[0030] Secondly, this application provides a preparation process for a composite slow-release material for groundwater remediation, employing the following technical solution:
[0031] A preparation process for a composite slow-release material for groundwater remediation includes the following steps:
[0032] Chitosan was added to glacial acetic acid solution and stirred to obtain a chitosan solution; polyvinyl alcohol was added to water and stirred to obtain a polyvinyl alcohol solution; a composite oxidant was dispersed in water and sonicated to obtain a mixture; the above mixture was added to the polyvinyl alcohol solution and stirred to obtain an emulsion; the emulsion was sonicated to obtain a refined emulsion; chitosan solution was added to the refined emulsion and stirred to obtain a mixed emulsion; genipin was dissolved in water to obtain a crosslinking agent solution; the crosslinking agent solution was added to the mixed emulsion, the pH was adjusted to acidic, the reaction was stirred, centrifuged, washed with water, and vacuum dried to obtain the inner layer. Microcapsules; starch is dispersed in water and heated and stirred to obtain a starch solution; peptone is dissolved in water and stirred to obtain a peptone solution; the peptone solution is added to the starch solution and stirred to obtain a mixed outer wall material emulsion; the inner microcapsules prepared above, glucose and self-Fenton mesoporous titanium dioxide are added to the above mixed outer wall material emulsion and stirred to obtain a mixed suspension; the pH of the mixed suspension is adjusted to acidic, and carbodiimide aqueous solution is added while stirring; after reaction, a product suspension is obtained; the product suspension is centrifuged, washed with water and vacuum dried to obtain a composite sustained-release material.
[0033] The composite slow-release material prepared according to the above steps can stably and persistently perform its pollutant degradation performance. The composite slow-release material has long-lasting oxidative degradation performance and can continuously promote the growth of microorganisms, working synergistically with microorganisms to improve the efficiency and durability of groundwater remediation.
[0034] In summary, this application includes at least one of the following beneficial technical effects:
[0035] 1. The composite oxidant can slowly release active oxygen to oxidize and degrade pollutants in groundwater, activate indigenous bacteria in situ, and promote the metabolism of pollutants by the bacteria. The inner wall material encapsulates the composite oxidant, slowing down its decomposition rate and enabling the composite slow-release material to provide long-term oxidative degradation capabilities. Glucose can serve as a carbon source to provide energy for the indigenous bacteria, promoting their metabolic growth and working synergistically with the composite oxidant to enhance the bacteria's ability to metabolize pollutants. The outer wall material combines self-Fenton mesoporous titanium dioxide and glucose with the composite oxidant encapsulated in the inner wall material, so that the entire system, while providing a barrier, can also effectively activate the self-Fenton system for pollutant degradation, working synergistically with the indigenous bacteria to enhance the groundwater remediation capacity.
[0036] 2. Mesoporous titanium dioxide possesses a large specific surface area and abundant pore structure, enabling it to adsorb pollutant molecules and bring them close to active sites. Simultaneously, mesoporous titanium dioxide can act as a stable carrier for iron-based complexes, promoting their uniform dispersion on its surface and enhancing the stability of the Fenton system. Titanium dioxide itself also exhibits good catalytic activity, enhancing the Fenton reaction's ability to degrade pollutants and improving degradation efficiency. Iron-based complexes can undergo the Fenton reaction, generating active free radicals that enhance the ability of composite oxidants to degrade pollutants. The hydroxyl radicals generated from the Fenton system can directly oxidize and decompose pollutants. After being activated by composite oxidants, they synergistically break down large organic molecules into smaller molecules, serving as a nutrient source for indigenous microbial communities, promoting their growth and metabolism. Furthermore, they work together with indigenous microbial communities to degrade pollutants in groundwater, improving the durability and stability of the remediation effect.
[0037] 3. Chitosan possesses excellent biocompatibility and adsorption properties, enabling it to interact with pollutants and slow down the release rate of calcium peroxide and sodium persulfate in the composite oxidant. Polyvinyl alcohol provides the wall material with flexibility and certain barrier properties, further regulating the release rate of the oxidant and allowing it to stably release oxygen over a longer period. The crosslinking agent connects chitosan and polyvinyl alcohol to form a stable three-dimensional network structure, enhancing the mechanical strength and stability of the wall material. This effectively prevents premature cracking of the wall material, thus preventing the premature and large-scale release of the oxidant. Consequently, it provides a long-lasting oxidizing environment for groundwater remediation, continuously degrading pollutants in groundwater and significantly improving the material's long-term degradation capacity, contributing to a more durable and stable groundwater remediation effect. Detailed Implementation
[0038] This application discloses a composite slow-release material for groundwater remediation and its preparation process. Unless otherwise specified, all raw materials used in this application can be obtained from commercially available sources. The following is a detailed description of this application in conjunction with the embodiments: Raw material description: Mesoporous titanium dioxide was purchased from Xi'an Qiyue Biotechnology Co., Ltd., ferric ethylenediaminetetraacetate complex was purchased from Xi'an Darwen Biotechnology Co., Ltd., chitosan (CAS No.: 9012-76-4), polyvinyl alcohol (CAS No.: 9002-89-5), genipin (CAS No.: 6902-77-8), corn starch, peptone (CAS No.: 73049-73-7), carbodiimide (dicyclohexylcarbodiimide (CAS No.: 538-75-0), glucose (CAS No.: 50-99-7), and maleic anhydride (CAS No.: 108-31-6).
[0039] Example 1
[0040] Preparation of Fenton mesoporous titanium dioxide
[0041] 20g of mesoporous titanium dioxide was added to an aqueous solution containing 4g of ferric ethylenediaminetetraacetate complex. After sonication for 30min, the mixture was stirred at 300rpm for 4h at 40℃, filtered, and dried in an oven at 80℃ to obtain self-Fenton mesoporous titanium dioxide.
[0042] The amount of inner wall material used to prepare the inner layer microcapsules was 30g, and the mass ratio of chitosan, polyvinyl alcohol and crosslinking agent in the inner wall material was 3:7:0.3.
[0043] Chitosan was added to a 2% (v / v) glacial acetic acid solution according to the above dosage, and the mixture was stirred at 500 rpm for 2 hours to prepare a 2% (w / w) chitosan solution. Polyvinyl alcohol was added to deionized water and stirred at 500 rpm for 4 hours at 95°C to prepare a 10% (w / w) polyvinyl alcohol solution. 20g of the composite oxidant was dispersed in 50mL of deionized water and sonicated for 20min to obtain a mixed solution. The mass ratio of calcium peroxide to sodium persulfate in the composite oxidant was 1:1.
[0044] The above mixture was added to a polyvinyl alcohol solution and stirred at 800 rpm for 20 minutes to obtain an emulsion. The emulsion was sonicated for 10 minutes to obtain a refined emulsion. Chitosan solution was added to the refined emulsion and stirred at 800 rpm for 20 minutes to obtain a mixed emulsion. Genipin was dissolved in deionized water to obtain a crosslinking agent solution. The crosslinking agent solution was added to the mixed emulsion for 1 hour. The pH was adjusted to 6 using 0.1 mol / L dilute hydrochloric acid aqueous solution. The reaction was carried out at 40°C with stirring at 800 rpm for 4 hours. After centrifugation, the mixture was washed with deionized water and dried under vacuum at 60°C to obtain the inner microcapsules.
[0045] Preparation of composite sustained-release materials
[0046] The outer wall material is 40g in weight, and the mass ratio of starch, peptone and carbodiimide in the outer wall material is 6:3:1.
[0047] Starch was dispersed in deionized water at a mass ratio of 1:5 and stirred at 500 rpm for 30 min at 60 °C to obtain a starch solution. Peptone was dissolved in deionized water at a mass ratio of 1:8 and stirred at 200 rpm for 15 min to obtain a peptone solution. The peptone solution was added to the starch solution over 30 min, and the mixture was stirred at 400 rpm for 30 min to obtain a mixed outer wall material emulsion. The prepared inner microcapsules, 10 g of glucose, and 5 g of Fenton mesoporous titanium dioxide were slowly added to the mixed outer wall material emulsion and stirred at 500 rpm for 30 min to obtain a mixed suspension. The pH of the mixed suspension was adjusted to 6, and carbodiimide aqueous solution was added while stirring at 500 rpm. The mixture was reacted at 30 °C for 3 h to obtain a product suspension. The product suspension was centrifuged, washed with deionized water, and vacuum dried at 60 °C to obtain the composite sustained-release material.
[0048] Example 2
[0049] Preparation of Fenton mesoporous titanium dioxide
[0050] 20g of mesoporous titanium dioxide was added to an aqueous solution containing 4g of ferric ethylenediaminetetraacetate complex. After sonication for 30min, the mixture was stirred at 300rpm for 4h at 40℃, filtered, and dried in an oven at 80℃ to obtain self-Fenton mesoporous titanium dioxide.
[0051] The amount of inner wall material used to prepare the inner layer microcapsules was 50g, and the mass ratio of chitosan, polyvinyl alcohol and crosslinking agent in the inner wall material was 5:5:0.3.
[0052] Chitosan was added to a 2% (v / v) glacial acetic acid solution according to the above dosage, and the mixture was stirred at 500 rpm for 2 hours to prepare a 2% (w / w) chitosan solution. Polyvinyl alcohol was added to deionized water and stirred at 500 rpm for 4 hours at 95°C to prepare a 10% (w / w) polyvinyl alcohol solution. 40g of the composite oxidant was dispersed in 50mL of deionized water and sonicated for 20 minutes to obtain a mixed solution. The mass ratio of calcium peroxide to sodium persulfate in the composite oxidant was 1:1.
[0053] The above mixture was added to a polyvinyl alcohol solution and stirred at 800 rpm for 20 minutes to obtain an emulsion. The emulsion was sonicated for 10 minutes to obtain a refined emulsion. Chitosan solution was added to the refined emulsion and stirred at 800 rpm for 20 minutes to obtain a mixed emulsion. Genipin was dissolved in deionized water to obtain a crosslinking agent solution. The crosslinking agent solution was added to the mixed emulsion for 1 hour. The pH was adjusted to 6 using 0.1 mol / L dilute hydrochloric acid aqueous solution. The reaction was carried out at 40°C with stirring at 800 rpm for 4 hours. After centrifugation, the mixture was washed with deionized water and dried under vacuum at 60°C to obtain the inner microcapsules.
[0054] Preparation of composite sustained-release materials
[0055] The outer wall material is 60g in weight, and the mass ratio of starch, peptone and carbodiimide in the outer wall material is 7:2:1.
[0056] Starch was dispersed in deionized water at a mass ratio of 1:5 and stirred at 500 rpm for 30 min at 60 °C to obtain a starch solution. Peptone was dissolved in deionized water at a mass ratio of 1:8 and stirred at 200 rpm for 15 min to obtain a peptone solution. The peptone solution was added to the starch solution over 30 min and stirred at 400 rpm for 30 min to obtain a mixed outer wall material emulsion. The prepared inner microcapsules, 20g of glucose, and 15g of Fenton mesoporous titanium dioxide were slowly added to the mixed outer wall material emulsion. The mixture was stirred at 500 rpm for 30 min to obtain a mixed suspension. The pH of the mixed suspension was adjusted to 6, and carbodiimide aqueous solution was added while stirring at 500 rpm. The mixture was reacted at 30°C for 3 h to obtain a product suspension. The product suspension was centrifuged, washed with deionized water, and then vacuum dried at 60°C to obtain the composite sustained-release material.
[0057] Example 3
[0058] Preparation of Fenton mesoporous titanium dioxide
[0059] 20g of mesoporous titanium dioxide was added to an aqueous solution containing 4g of ferric ethylenediaminetetraacetate complex. After sonication for 30min, the mixture was stirred at 300rpm for 4h at 40℃, filtered, and dried in an oven at 80℃ to obtain self-Fenton mesoporous titanium dioxide.
[0060] The amount of inner wall material used to prepare the inner layer microcapsules was 40g, and the mass ratio of chitosan, polyvinyl alcohol and crosslinking agent in the inner wall material was 4:6:0.3.
[0061] Chitosan was added to a 2% (v / v) glacial acetic acid solution according to the above dosage, and the mixture was stirred at 500 rpm for 2 hours to prepare a 2% (w / w) chitosan solution. Polyvinyl alcohol was added to deionized water and stirred at 500 rpm for 4 hours at 95°C to prepare a 10% (w / w) polyvinyl alcohol solution. 30g of the composite oxidant was dispersed in 50mL of deionized water and sonicated for 20 minutes to obtain a mixed solution. The mass ratio of calcium peroxide to sodium persulfate in the composite oxidant was 1:1.
[0062] The above mixture was added to a polyvinyl alcohol solution and stirred at 800 rpm for 20 minutes to obtain an emulsion. The emulsion was sonicated for 10 minutes to obtain a refined emulsion. Chitosan solution was added to the refined emulsion and stirred at 800 rpm for 20 minutes to obtain a mixed emulsion. Genipin was dissolved in deionized water to obtain a crosslinking agent solution. The crosslinking agent solution was added to the mixed emulsion for 1 hour. The pH was adjusted to 6 using 0.1 mol / L dilute hydrochloric acid aqueous solution. The reaction was carried out at 40°C with stirring at 800 rpm for 4 hours. After centrifugation, the mixture was washed with deionized water and dried under vacuum at 60°C to obtain the inner microcapsules.
[0063] Preparation of composite sustained-release materials
[0064] The outer wall material is used in a quantity of 50g, and the mass ratio of starch, peptone and carbodiimide in the outer wall material is 6.5:2.5:1.
[0065] Starch was dispersed in deionized water at a mass ratio of 1:5 and stirred at 500 rpm for 30 min at 60 °C to obtain a starch solution. Peptone was dissolved in deionized water at a mass ratio of 1:8 and stirred at 200 rpm for 15 min to obtain a peptone solution. The peptone solution was added to the starch solution over 30 min and stirred at 400 rpm for 30 min to obtain a mixed outer wall material emulsion. The prepared inner microcapsules, 15g of glucose, and 10g of Fenton mesoporous titanium dioxide were slowly added to the mixed outer wall material emulsion. The mixture was stirred at 500 rpm for 30 min to obtain a mixed suspension. The pH of the mixed suspension was adjusted to 6, and carbodiimide aqueous solution was added while stirring at 500 rpm. The mixture was reacted at 30°C for 3 h to obtain a product suspension. The product suspension was centrifuged, washed with deionized water, and then vacuum dried at 60°C to obtain the composite sustained-release material.
[0066] Example 4
[0067] Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that the crosslinking agent in the inner wall material is replaced with maleic anhydride in Example 4.
[0068] Example 5
[0069] Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that the mass ratio of chitosan, polyvinyl alcohol and crosslinking agent in the inner wall material of Example 5 is 2:8:0.3.
[0070] Example 6
[0071] Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that the mass ratio of chitosan, polyvinyl alcohol and crosslinking agent in the inner wall material of Example 6 is 6:4:0.3.
[0072] Example 7
[0073] Example 7 is based on Example 3. The only difference between Example 7 and Example 3 is that polyvinyl alcohol is not added when preparing the inner wall material in Example 7.
[0074] Example 8
[0075] Example 8 is based on Example 3. The only difference between Example 8 and Example 3 is that the mass ratio of starch, peptone and carbodiimide in the outer wall material in Example 8 is 5:4:1.
[0076] Example 9
[0077] Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that the mass ratio of starch, peptone and carbodiimide in the outer wall material of Example 9 is 8:1:1.
[0078] Example 10
[0079] Example 10 is based on Example 3. The only difference between Example 10 and Example 3 is that peptone is not added when preparing the outer wall material in Example 10.
[0080] Comparative Example 1
[0081] Comparative Example 1 is based on Example 3. The only difference between Comparative Example 1 and Example 3 is that the composite oxidant in Comparative Example 1 is replaced with calcium peroxide.
[0082] Comparative Example 2
[0083] Comparative Example 2 is based on Example 3. The only difference between Comparative Example 2 and Example 3 is that Comparative Example 2 replaces self-Fenton mesoporous titanium dioxide with mesoporous titanium dioxide.
[0084] Comparative Example 3
[0085] Comparative Example 3 is based on Example 3. The only difference between Comparative Example 3 and Example 3 is that Comparative Example 3 replaces Fenton mesoporous titanium dioxide with ferric ethylenediaminetetraacetate complex.
[0086] Performance testing
[0087] (1) Oxygen release performance test: Deionized water was deoxygenated by adding sodium sulfite aqueous solution. After the dissolved oxygen content was measured to be 0 mg / L, the oxygen-free deionized water was injected into a container containing composite slow-release material. The dissolved oxygen concentration in the system was tested at 10 days, 15 days and 30 days. Each sample was tested three times, and the average value was taken after measurement. The results are recorded in Table 1.
[0088] (2) Pollutant degradation performance test: After reactivating Pseudomonas putida, it was inoculated into a glass bottle containing inorganic salt culture medium, so that the initial OD600 value of Pseudomonas putida in the culture medium was 0.01, and the concentration of benzene, toluene, ethylbenzene and xylene was 0.5 mg / L. Composite slow-release material was added to the glass bottle. After seven days of incubation in the dark, the removal rate of benzene, toluene, ethylbenzene and xylene in the glass bottle and the OD600 value of the microorganism were tested. Each sample was tested three times, and the average value was taken after measurement. The results are recorded in Table 1.
[0089] Table 1. Test results of oxygen release performance and pollutant degradation performance
[0090]
[0091]
[0092] As shown in Table 1, the dissolved oxygen concentration in Examples 1-4 was greater than 7.65 mg / L at 10 days, greater than 7.06 mg / L at 20 days, and greater than 6.34 mg / L at 30 days. The removal rates for benzene were greater than 39.2%, toluene greater than 43.8%, ethylbenzene greater than 41.5%, and xylene greater than 40.7%. The OD600 value of the microorganisms after cultivation was greater than 1.55. This demonstrates that the composite slow-release material prepared in this application can effectively enhance the metabolism of organisms, work synergistically with microorganisms, and improve the groundwater remediation capacity.
[0093] As shown in Table 1, the only difference between Examples 5, 6, and 7 and Example 3 is that the proportion of synthetic substances in the inner wall material was adjusted in Examples 5 and 6, and polyvinyl alcohol was not added in Example 7. Compared with Example 3, the pollutant degradation performance of Examples 5, 6, and 7 decreased. This is because the composition and proportion of the inner wall material affect the stability of the inner wall material, which affects the release of the composite oxidant, and thus affects the synergistic effect with microorganisms, resulting in a decrease in the pollutant degradation performance.
[0094] As shown in Table 1, the only difference between Examples 8, 9, and 10 and Example 3 is that the composition ratio of the outer wall material was adjusted in Examples 8 and 9, and peptone was not added in Example 9. Compared with Example 3, Examples 8, 9, and 10 showed a decrease in the ability to degrade pollutants. This is because the composition and ratio of the outer wall material affect the overall stability of the composite slow-release material, resulting in a decrease in the adsorption performance of pollutants, the promotion effect on microbial growth, the oxidation performance, and the synergistic effect with microorganisms, thus leading to a decrease in the pollutant degradation performance.
[0095] As shown in Table 1, the differences between Comparative Examples 1, 2, and 3 and Example 3 are only as follows: in Comparative Example 1, the composite oxidant was replaced with calcium peroxide; in Comparative Example 2, the self-Fenton mesoporous titanium dioxide was replaced with mesoporous titanium dioxide; and in Comparative Example 3, the self-Fenton mesoporous titanium dioxide was replaced with an ethylenediaminetetraacetic acid iron complex. Compared with Example 3, the degradation performance of pollutants in Comparative Examples 1, 2, and 3 was significantly reduced. This is because replacing the composite oxidant with calcium peroxide, calcium peroxide alone lacks synergistic effect, resulting in a decrease in oxidative degradation performance and a decrease in the promoting effect on the self-Fenton system. Replacing the self-Fenton mesoporous titanium dioxide with a single mesoporous titanium dioxide or an iron-based complex affects the self-Fenton system, reduces its stability, and decreases its catalytic degradation performance, thus significantly reducing the degradation performance of pollutants and lowering the remediation effect.
[0096] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.
Claims
1. A composite slow-release material for groundwater remediation, characterized in that: The raw materials for preparation include the following components in parts by weight: 20-40 parts of compound oxidant 30-50 parts of inner wall material 10-20 servings of glucose 40-60 parts of outer wall material 5-15 parts of Fenton mesoporous titanium dioxide; The composite oxidant includes calcium peroxide and sodium persulfate; The inner wall material includes chitosan, polyvinyl alcohol, and a crosslinking agent; The raw materials for preparing the self-Fenton mesoporous titanium dioxide include mesoporous titanium dioxide bulk and ferric ethylenediaminetetraacetate complex; The outer wall material comprises starch, peptone, and carbodiimide.
2. The composite slow-release material for groundwater remediation according to claim 1, characterized in that: The mass ratio of chitosan, polyvinyl alcohol and crosslinking agent is (3-5):(5-7):0.
3.
3. The composite slow-release material for groundwater remediation according to claim 2, characterized in that: The crosslinking agent includes one of genipin and maleic anhydride.
4. The composite slow-release material for groundwater remediation according to claim 1, characterized in that: The mass ratio of starch, peptone, and carbodiimide is (6-7):(2-3):
1.
5. A preparation process for a composite slow-release material used in groundwater remediation as described in any one of claims 1-4, characterized in that: Includes the following steps: Chitosan was added to glacial acetic acid solution and stirred to obtain a chitosan solution; polyvinyl alcohol was added to water and stirred to obtain a polyvinyl alcohol solution; a composite oxidant was dispersed in water and sonicated to obtain a mixture; the above mixture was added to the polyvinyl alcohol solution and stirred to obtain an emulsion; the emulsion was sonicated to obtain a refined emulsion; chitosan solution was added to the refined emulsion and stirred to obtain a mixed emulsion; genipin was dissolved in water to obtain a crosslinking agent solution; the crosslinking agent solution was added to the mixed emulsion, the pH was adjusted to acidic, the reaction was stirred, centrifuged, washed with water, and vacuum dried to obtain inner layer microcapsules; Starch was dispersed in water and heated and stirred to obtain a starch solution; peptone was dissolved in water and stirred to obtain a peptone solution; the peptone solution was added to the starch solution and stirred to obtain a mixed outer wall material emulsion; the inner microcapsules, glucose, and self-Fenton mesoporous titanium dioxide prepared above were added to the above mixed outer wall material emulsion and stirred to obtain a mixed suspension; the pH of the mixed suspension was adjusted to acidic, and carbodiimide aqueous solution was added while stirring; after the reaction, a product suspension was obtained; the product suspension was centrifuged, washed with water, and vacuum dried to obtain the composite sustained-release material.