Composite slow-release material for groundwater remediation and preparation process of composite slow-release material

Abstract

The invention relates to a composite slow-release material for groundwater remediation and a preparation process thereof, and relates to the technical field of groundwater remediation materials.The composite slow-release material is prepared from, by mass, 20-40 parts of a composite oxidizing agent, 30-50 parts of an inner-layer wall material, 10-20 parts of glucose, 40-60 parts of an outer-layer wall material and 5-15 parts of self-Fenton mesoporous titanium dioxide. The preparation process comprises the following steps: preparing the self-Fenton mesoporous titanium dioxide, preparing the inner-layer micro-capsule and preparing the composite sustained-release material. The composite slow-release material has the effect of improving the pollutant degradation performance of the composite slow-release material, the composite slow-release material has good oxidative degradation capacity, growth and metabolism of microorganisms in underground water can be promoted, the composite slow-release material cooperates with the microorganisms to degrade pollutants, and the removal efficiency of the pollutants and the durability of the repairing effect are improved.

Description

Technical Field

[0001] The present application relates to the technical field of groundwater remediation materials, and in particular to a composite slow-release material for groundwater remediation and a preparation process thereof. Background Art

[0002] Groundwater remediation is an important task in the field of environmental protection. With the acceleration of industrialization and the continuous expansion of human activities, the pollution of groundwater resources has become more and more serious, which not only threatens human health, but also directly affects the balance of the ecosystem. In response to this problem, scientists are constantly developing new technologies to improve the efficiency and sustainability of groundwater remediation. Among them, composite slow-release materials have gradually become one of the research hotspots due to their outstanding performance in capturing and degrading pollutants.

[0003] Among the existing groundwater remediation technologies, multiple methods are usually used, such as activated carbon adsorption, chemical oxidation and biological remediation. Among them, the activated carbon adsorption method relies on the microporous structure of the activated carbon itself to adsorb pollutants in the water, and the chemical oxidation method achieves the purpose of purification by adding oxidants to oxidize and decompose pollutants. In addition, biological remediation technology uses the metabolism of microorganisms to degrade pollutants to achieve groundwater purification.

[0004] However, the above existing technologies have their own shortcomings. For example, the activated carbon adsorption method may have limited adsorption capacity and is difficult to remove certain difficult-to-degrade pollutants; the chemical oxidation method may produce secondary pollution and has relatively high costs; although the biological remediation technology is green and environmentally friendly, it is inefficient in treating certain specific pollutants. Therefore, it is necessary to provide a new type of composite slow-release material to solve the technical problems of groundwater remediation. Summary of the invention

[0005] In order to improve the effect of groundwater remediation, the present application provides a composite slow-release material for groundwater remediation and a preparation process thereof.

[0006] The present application provides a composite slow-release material for groundwater remediation and a preparation process thereof using the following technical solutions: In the first aspect, the present application provides a composite slow-release material for groundwater remediation, which adopts the following technical solution: A composite slow-release material for groundwater remediation, the raw materials for preparation include the following components in parts by mass: Composite oxidant 20-40 parts 30-50 pieces of inner wall material Glucose 10-20 parts The outer wall material is 40-60 parts and the Fenton mesoporous titanium dioxide is 5-15 parts.

[0007] The composite oxidant can slowly release active oxygen, oxidatively degrade pollutants in groundwater, activate indigenous flora in groundwater in situ, and promote the metabolism of pollutants by the flora; the inner wall material wraps the composite oxidant to slow down the decomposition rate of the composite oxidant, so that the composite slow-release material can provide long-term oxidative degradation ability; glucose can be used as a carbon source to provide energy for indigenous flora, promote its metabolic growth, and synergize with the composite oxidant to enhance the ability of the flora to metabolize pollutants; the outer wall material combines self-Fenton mesoporous titanium dioxide and glucose with the composite oxidant wrapped by the inner wall material, so that the entire system has a barrier function while the composite oxidant can activate the self-Fenton system for pollutant degradation in a long term, synergize with indigenous flora, and enhance the ability of groundwater remediation.

[0008] Preferably, the raw materials for preparing the self-Fenton mesoporous titanium dioxide include a mesoporous titanium dioxide body and an iron-based complex.

[0009] Mesoporous titanium dioxide has a large specific surface area and rich pore structure, which can adsorb pollutant molecules and bring them close to active sites. At the same time, mesoporous titanium dioxide can serve as a stable carrier for iron-based complexes, promoting their uniform dispersion on the surface of mesoporous titanium dioxide and improving the stability of the Fenton system. Titanium dioxide itself also has good catalytic reaction activity, which can enhance the ability of the Fenton reaction to degrade pollutants and improve degradation efficiency. Iron-based complexes can undergo Fenton reactions to produce active free radicals, thereby enhancing 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 the composite oxidant, they synergize with it to decompose large organic molecules into small molecules, serving as a nutrient source for indigenous flora, promoting their growth and metabolism, and then working together with the indigenous flora to degrade pollutants in groundwater and improve the durability and stability of the remediation effect.

[0010] Preferably, the iron-based complex comprises ethylenediaminetetraacetic acid iron complex.

[0011] The iron ions in the ethylenediaminetetraacetic acid iron complex can stimulate the Fenton reaction through the peroxide released by the composite oxidant wrapped in the inner wall material, continuously produce strong oxidizing free radicals, attack various organic pollutants in the groundwater, and decompose them into small molecules, thereby effectively improving the degradation efficiency of pollutants; these small molecule decomposition products can serve as nutrients for indigenous flora, promote the growth and reproduction of indigenous flora, and enhance the ability of indigenous flora to degrade pollutants. At the same time, indigenous flora will change the physical and chemical properties of the local environment during metabolism, so that the ethylenediaminetetraacetic acid iron complex can remain active and promote the continuation of the Fenton reaction. The synergistic effect of the two can effectively improve the comprehensiveness and durability of the repair effect.

[0012] Preferably, the composite oxidant comprises calcium peroxide and sodium persulfate.

[0013] Calcium peroxide can slowly release 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. On the one hand, they can continuously provide oxidizing capacity and effectively degrade various organic pollutants in groundwater, including difficult-to-degrade organic matter, and decompose them into harmless or low-harm small molecules; long-term oxygen release can promote the growth of microorganisms, thereby synergizing with indigenous flora to improve the degradation efficiency of pollutants and thus improve the remediation effect.

[0014] Preferably, the inner wall material comprises chitosan, polyvinyl alcohol and a cross-linking agent.

[0015] Chitosan has good biocompatibility and adsorption properties, can interact with pollutants, and delay the release rate of calcium peroxide and sodium persulfate in the composite oxidant; polyvinyl alcohol provides flexibility and certain barrier properties for the wall material, further adjusts the release rate of the oxidant, and enables it to stably release oxygen over a long period of time; the cross-linking agent connects chitosan and polyvinyl alcohol to form a stable three-dimensional network structure, which enhances the mechanical strength and stability of the wall material, effectively preventing the wall material from rupturing prematurely and causing the oxidant to be released in large quantities in advance, thereby providing a long-term oxidizing environment for groundwater remediation, continuously degrading pollutants in groundwater, significantly improving the long-term degradation ability of the material, and helping to achieve a more lasting and stable groundwater remediation effect.

[0016] Preferably, the mass ratio of chitosan, polyvinyl alcohol and cross-linking agent is (3-5): (5-7): 0.3.

[0017] The inner wall material prepared according to the above mass ratio has good stability and pore structure, and can effectively improve the repair effect of the composite sustained-release material.

[0018] Preferably, the cross-linking agent comprises one of genipin and maleic anhydride.

[0019] Genipin and maleic anhydride can react chemically 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 oxidative environment for groundwater remediation; the network structure formed by cross-linking of genipin or maleic anhydride has a specific porosity and permeability. By controlling the amount of cross-linking agent and the 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 microorganisms to attach and grow. Maleic anhydride can also be well compatible with the groundwater environment, promoting the composite slow-release material to effectively play a repair role in the complex and changeable groundwater environment.

[0020] Preferably, the outer wall material comprises starch, peptone and carbodiimide.

[0021] Starch has good film-forming and adsorption properties, and can form a protective film on the outer layer of the material, which can well coat the components in the composite slow-release material and adsorb and intercept pollutants; peptone is rich in various amino acids, which adds abundant active groups and nutrients to the outer wall material, can improve the biocompatibility of the wall material, and is conducive to interaction with microorganisms in the groundwater environment, and promotes the attachment and growth of microorganisms on the surface of the wall material; carbodiimide can connect starch and peptone molecules through chemical bonds to form a three-dimensional network structure, which significantly enhances the mechanical strength and stability of the outer wall material, and prevents the wall material from breaking or degrading due to water flow impact, physical pressure or chemical erosion in the groundwater environment, so that the composite slow-release material can play a role in a long-term and stable manner, and improve the removal efficiency of pollutants and the durability of the repair effect.

[0022] Preferably, the mass ratio of starch, peptone and carbodiimide is (6-7):(2-3):1.

[0023] The outer wall material prepared according to the above mass ratio has good stability and adsorption performance, can provide nutrients for microorganisms, and synergistically improve the removal efficiency of pollutants.

[0024] In the second aspect, the present application provides a preparation process of a composite slow-release material for groundwater remediation, which adopts the following technical scheme: A preparation process of a composite slow-release material for groundwater remediation comprises the following steps: Chitosan is added to glacial acetic acid solution and stirred to obtain chitosan solution; polyvinyl alcohol is added to water and stirred to obtain polyvinyl alcohol solution; a composite oxidant is dispersed in water and subjected to ultrasonic treatment to obtain a mixed solution; the mixed solution is added to the polyvinyl alcohol solution and stirred to obtain an emulsion, and the emulsion is subjected to ultrasonic treatment to obtain a refined emulsion; the chitosan solution is added to the refined emulsion and stirred to obtain a mixed emulsion; genipin is dissolved in water to obtain a crosslinker solution, the crosslinker solution is added to the mixed emulsion, the pH is adjusted to acidic, the reaction is stirred, centrifuged, washed with water, and vacuum dried to obtain an inner layer microcapsules; dispersing starch in water, heating and stirring to obtain a starch solution; dissolving peptone in water, stirring to obtain a peptone solution; adding the peptone solution to the starch solution, stirring to obtain a mixed outer wall material emulsion; adding the inner layer microcapsules, glucose and self-Fenton mesoporous titanium dioxide prepared above to the mixed outer wall material emulsion, stirring to obtain a mixed suspension, adjusting the pH of the mixed suspension to acidic, adding a carbodiimide aqueous solution, stirring while adding, and obtaining a product suspension after reaction; centrifuging the product suspension, washing with water and vacuum drying to obtain a composite sustained-release material.

[0025] The composite slow-release material prepared according to the above steps can stably and durably perform the performance of degrading pollutants. The composite slow-release material has long-lasting oxidative degradation performance, and can continuously promote the growth of microorganisms, synergize with microorganisms, and improve the efficiency and durability of groundwater remediation.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: 1. The composite oxidant can slowly release active oxygen, oxidatively degrade pollutants in groundwater, activate indigenous flora in groundwater in situ, and promote the metabolism of pollutants by the flora; the inner wall material wraps the composite oxidant to slow down the decomposition rate of the composite oxidant, so that the composite slow-release material can provide long-term oxidative degradation ability; glucose can be used as a carbon source to provide energy for indigenous flora, promote its metabolic growth, and synergize with the composite oxidant to enhance the ability of the flora to metabolize pollutants; the outer wall material combines self-Fenton mesoporous titanium dioxide and glucose with the composite oxidant wrapped by the inner wall material, so that the entire system has a barrier function while the composite oxidant can activate the self-Fenton system for pollutant degradation in a long term, synergize with indigenous flora, and enhance the ability of groundwater remediation.

[0027] 2. Mesoporous titanium dioxide has a large specific surface area and rich pore structure, which can adsorb pollutant molecules and bring them close to active sites. At the same time, mesoporous titanium dioxide can serve as a stable carrier for iron-based complexes, promoting their uniform dispersion on the surface of mesoporous titanium dioxide and improving the stability of the Fenton system. Titanium dioxide itself also has good catalytic reaction activity, which can enhance the ability of the Fenton reaction to degrade pollutants and improve degradation efficiency. Iron-based complexes can undergo Fenton reactions to produce active free radicals, thereby enhancing 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 the composite oxidant, they synergize with it to decompose large organic molecules into small molecules, serving as a nutrient source for indigenous flora, promoting their growth and metabolism, and then working together with indigenous flora to degrade pollutants in groundwater and improve the durability and stability of the remediation effect.

[0028] 3. Chitosan has good biocompatibility and adsorption properties, can interact with pollutants, and delay the release rate of calcium peroxide and sodium persulfate in the composite oxidant; polyvinyl alcohol provides flexibility and certain barrier properties for the wall material, further adjusts the release rate of the oxidant, and enables it to stably release oxygen over a long period of time; the cross-linking agent connects chitosan and polyvinyl alcohol to form a stable three-dimensional network structure, which enhances the mechanical strength and stability of the wall material, effectively preventing the wall material from rupturing prematurely and causing the oxidant to be released in large quantities in advance, thereby providing a long-term oxidizing environment for groundwater remediation, continuously degrading pollutants in groundwater, significantly improving the long-term degradation ability of the material, and helping to achieve a more lasting and stable groundwater remediation effect. DETAILED DESCRIPTION

[0029] The embodiment of the present application discloses a composite sustained-release material for groundwater remediation and a preparation process thereof. The raw materials used in the present application can be obtained through commercially available raw materials unless otherwise specified. The present application is further described in detail in conjunction with the embodiments below: Raw material description: Mesoporous titanium dioxide was purchased from Xi'an Qiyue Biotechnology Co., Ltd., ethylenediaminetetraacetic acid iron 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), starch is corn starch, peptone (CAS No.: 73049-73-7), carbodiimide is dicyclohexylcarbodiimide (CAS No.: 538-75-0), glucose (CAS No.: 50-99-7), maleic anhydride (CAS No.: 108-31-6).

[0030] Example 1 Prepared from Fenton mesoporous titanium dioxide 20 g of mesoporous titanium dioxide was added to an aqueous solution containing 4 g of ethylenediaminetetraacetic acid iron complex, and after ultrasonication for 30 min, the mixture was stirred at 300 rpm at 40° C. for 4 h, filtered, and dried in an oven at 80° C. to obtain self-Fenton mesoporous titanium dioxide.

[0031] The amount of inner wall material used to prepare the inner microcapsules is 30 g, and the mass ratio of chitosan, polyvinyl alcohol and cross-linking agent in the inner wall material is 3:7:0.3.

[0032] Chitosan was added into a 2% glacial acetic acid solution according to the above dosage, and stirred at 500 rpm for 2 hours to prepare a chitosan solution with a mass fraction of 2%; polyvinyl alcohol was added into deionized water, and stirred at 500 rpm for 4 hours at 95°C to prepare a polyvinyl alcohol solution with a mass fraction of 10%; 20 g of the composite oxidant was dispersed into 50 mL of deionized water, and ultrasonicated for 20 minutes to obtain a mixed solution, in which the mass ratio of calcium peroxide to sodium persulfate in the composite oxidant was 1:1.

[0033] The mixed solution was added to the polyvinyl alcohol solution, stirred at a speed of 800 rpm, and the addition was completed within 20 minutes to obtain an emulsion, and the emulsion was ultrasonicated for 10 minutes to obtain a refined emulsion; chitosan solution was added to the refined emulsion, stirred at a speed of 800 rpm, and the addition was completed within 20 minutes to obtain a mixed emulsion; genipin was dissolved in deionized water to obtain a cross-linker solution, and the cross-linker solution was added to the mixed emulsion, and the addition was completed within 1 hour, and the pH was adjusted to 6 with a 0.1 mol / L dilute hydrochloric acid aqueous solution, and the reaction was stirred at a speed of 800 rpm at 40°C for 4 hours, washed with deionized water after centrifugation, and vacuum dried at 60°C to obtain inner layer microcapsules.

[0034] Preparation of composite sustained-release materials The amount of the outer wall material is 40 g, and the mass ratio of starch, peptone and carbodiimide in the outer wall material is 6:3:1.

[0035] The starch was dispersed in deionized water, the mass ratio of starch to deionized water was 1:5, and the mixture was stirred at 500 rpm for 30 minutes at 60°C to obtain a starch solution; peptone was dissolved in deionized water, the mass ratio of peptone to deionized water was 1:8, and the mixture was stirred at 200 rpm for 15 minutes to obtain a peptone solution; the peptone solution was added to the starch solution within 30 minutes, and the mixture was stirred at 400 rpm for 30 minutes to obtain a mixed outer wall material emulsion; the inner layer microcapsules prepared above, 10 g of glucose and 5 g of self-Fenton mesoporous titanium dioxide were slowly added to the mixed outer wall material emulsion, and the mixture was stirred at 500 rpm for 30 minutes to obtain a mixed suspension, the pH of the mixed suspension was adjusted to 6, a carbodiimide aqueous solution was added, and the mixture was stirred at 500 rpm while being added, and the mixture was reacted at 30°C for 3 hours to obtain a product suspension; the product suspension was centrifuged, washed with deionized water, and then vacuum dried at 60°C to obtain a composite sustained-release material.

[0036] Example 2 Prepared from Fenton mesoporous titanium dioxide 20 g of mesoporous titanium dioxide was added to an aqueous solution containing 4 g of ethylenediaminetetraacetic acid iron complex, and after ultrasonication for 30 min, the mixture was stirred at 300 rpm at 40° C. for 4 h, filtered, and dried in an oven at 80° C. to obtain self-Fenton mesoporous titanium dioxide.

[0037] The amount of inner wall material used to prepare the inner microcapsules is 50 g, and the mass ratio of chitosan, polyvinyl alcohol and cross-linking agent in the inner wall material is 5:5:0.3.

[0038] Chitosan was added into a 2% glacial acetic acid solution according to the above dosage, and stirred at 500 rpm for 2 hours to prepare a chitosan solution with a mass fraction of 2%; polyvinyl alcohol was added into deionized water, and stirred at 500 rpm for 4 hours at 95°C to prepare a polyvinyl alcohol solution with a mass fraction of 10%; 40 g of the composite oxidant was dispersed into 50 mL of deionized water, and ultrasonicated for 20 minutes to obtain a mixed solution, in which the mass ratio of calcium peroxide to sodium persulfate in the composite oxidant was 1:1.

[0039] The mixed solution was added to the polyvinyl alcohol solution, stirred at a speed of 800 rpm, and the addition was completed within 20 minutes to obtain an emulsion, and the emulsion was ultrasonicated for 10 minutes to obtain a refined emulsion; chitosan solution was added to the refined emulsion, stirred at a speed of 800 rpm, and the addition was completed within 20 minutes to obtain a mixed emulsion; genipin was dissolved in deionized water to obtain a cross-linker solution, and the cross-linker solution was added to the mixed emulsion, and the addition was completed within 1 hour, and the pH was adjusted to 6 with a 0.1 mol / L dilute hydrochloric acid aqueous solution, and the reaction was stirred at a speed of 800 rpm at 40°C for 4 hours, washed with deionized water after centrifugation, and vacuum dried at 60°C to obtain inner layer microcapsules.

[0040] Preparation of composite sustained-release materials The amount of the outer wall material is 60 g, and the mass ratio of starch, peptone and carbodiimide in the outer wall material is 7:2:1.

[0041] Disperse starch in deionized water, the mass ratio of starch to deionized water is 1:5, stir at 60°C at 500 rpm for 30 minutes to obtain a starch solution; dissolve peptone in deionized water, the mass ratio of peptone to deionized water is 1:8, stir at 200 rpm for 15 minutes to obtain a peptone solution; add the peptone solution to the starch solution within 30 minutes, stir at 400 rpm for 30 minutes to obtain a mixed outer wall material emulsion; The prepared inner layer microcapsules, 20 g of glucose and 15 g of self-Fenton mesoporous titanium dioxide were slowly added to the mixed outer layer wall material emulsion, stirred at 500 rpm for 30 min to obtain a mixed suspension, the pH of the mixed suspension was adjusted to 6, and a carbodiimide aqueous solution was added, stirred at 500 rpm while adding, and 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 a composite sustained-release material.

[0042] Example 3 Prepared from Fenton mesoporous titanium dioxide 20 g of mesoporous titanium dioxide was added to an aqueous solution containing 4 g of ethylenediaminetetraacetic acid iron complex, and after ultrasonication for 30 min, the mixture was stirred at 300 rpm at 40° C. for 4 h, filtered, and dried in an oven at 80° C. to obtain self-Fenton mesoporous titanium dioxide.

[0043] The amount of inner wall material used to prepare the inner microcapsules is 40 g, and the mass ratio of chitosan, polyvinyl alcohol and cross-linking agent in the inner wall material is 4:6:0.3.

[0044] Chitosan was added into a 2% glacial acetic acid solution according to the above dosage, and stirred at 500 rpm for 2 hours to prepare a chitosan solution with a mass fraction of 2%; polyvinyl alcohol was added into deionized water, and stirred at 500 rpm for 4 hours at 95°C to prepare a polyvinyl alcohol solution with a mass fraction of 10%; 30 g of the composite oxidant was dispersed into 50 mL of deionized water, and ultrasonicated for 20 minutes to obtain a mixed solution, in which the mass ratio of calcium peroxide to sodium persulfate in the composite oxidant was 1:1.

[0045] The mixed solution was added to the polyvinyl alcohol solution, stirred at a speed of 800 rpm, and the addition was completed within 20 minutes to obtain an emulsion, and the emulsion was ultrasonicated for 10 minutes to obtain a refined emulsion; chitosan solution was added to the refined emulsion, stirred at a speed of 800 rpm, and the addition was completed within 20 minutes to obtain a mixed emulsion; genipin was dissolved in deionized water to obtain a cross-linker solution, and the cross-linker solution was added to the mixed emulsion, and the addition was completed within 1 hour, and the pH was adjusted to 6 with a 0.1 mol / L dilute hydrochloric acid aqueous solution, and the reaction was stirred at a speed of 800 rpm at 40°C for 4 hours, washed with deionized water after centrifugation, and vacuum dried at 60°C to obtain inner layer microcapsules.

[0046] Preparation of composite sustained-release materials The amount of the outer wall material is 50 g, and the mass ratio of starch, peptone and carbodiimide in the outer wall material is 6.5:2.5:1.

[0047] Disperse starch in deionized water, the mass ratio of starch to deionized water is 1:5, stir at 60°C at 500 rpm for 30 minutes to obtain a starch solution; dissolve peptone in deionized water, the mass ratio of peptone to deionized water is 1:8, stir at 200 rpm for 15 minutes to obtain a peptone solution; add the peptone solution to the starch solution within 30 minutes, stir at 400 rpm for 30 minutes to obtain a mixed outer wall material emulsion; The prepared inner layer microcapsules, 15 g of glucose and 10 g of self-Fenton mesoporous titanium dioxide were slowly added to the mixed outer layer wall material emulsion, stirred at 500 rpm for 30 min to obtain a mixed suspension, the pH of the mixed suspension was adjusted to 6, and a carbodiimide aqueous solution was added, stirred at 500 rpm while adding, and 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 a composite sustained-release material.

[0048] Example 4 Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that in Example 4, the cross-linking agent in the inner wall material is replaced by maleic anhydride.

[0049] Example 5 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 cross-linking agent in the inner wall material in Example 5 is 2:8:0.3.

[0050] Example 6 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 cross-linking agent in the inner wall material in Example 6 is 6:4:0.3.

[0051] Example 7 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.

[0052] Example 8 Example 8 is based on Example 3, and 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.

[0053] Example 9 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 in Example 9 is 8:1:1.

[0054] Example 10 Example 10 is based on Example 3, and the only difference between Example 10 and Example 3 is that in Example 10, peptone is not added when preparing the outer wall material.

[0055] Comparative Example 1 Comparative Example 1 is based on Example 3, and the only difference between Comparative Example 1 and Example 3 is that in Comparative Example 1, the composite oxidant is replaced by calcium peroxide.

[0056] Comparative Example 2 Comparative Example 2 is based on Example 3, and the only difference between Comparative Example 2 and Example 3 is that the Self-Fenton mesoporous titanium dioxide is replaced by mesoporous titanium dioxide in Comparative Example 2.

[0057] Comparative Example 3 Comparative Example 3 is based on Example 3. The only difference between Comparative Example 3 and Example 3 is that the self-Fenton mesoporous titanium dioxide is replaced by ethylenediaminetetraacetic acid iron complex in Comparative Example 3.

[0058] Performance testing (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 the container containing the composite sustained-release material. The concentration of dissolved oxygen in the system was tested at 10 days, 15 days and 30 days respectively. Each sample was tested three times, and the average value was taken after measurement. The results are recorded in Table 1.

[0059] (2) Pollutant degradation performance test: After Pseudomonas putida was revived, it was inoculated into a glass bottle containing an inorganic salt culture medium so that the initial OD600 value of Pseudomonas putida in the culture medium was 0.01, and the concentrations of benzene, toluene, ethylbenzene and xylene were 0.5 mg / L. The composite sustained-release material was added to the glass bottle. After seven days of dark culture, the removal rates of benzene, toluene, ethylbenzene and xylene in the glass bottle, as well as the OD600 value of the microorganisms were tested. Each sample was tested three times, and the average value was taken after measurement. The results are recorded in Table 1.

[0060] Table 1 Test results of oxygen release performance and pollutant degradation performance As can be seen from Table 1, the dissolved oxygen concentration of Examples 1-4 at 10 days is greater than 7.65 mg / L, the dissolved oxygen concentration at 20 days is greater than 7.06 mg / L, and the dissolved oxygen concentration at 30 days is greater than 6.34 mg / L. The removal rate of benzene is greater than 39.2%, the removal rate of toluene is greater than 43.8%, the removal rate of ethylbenzene is greater than 41.5%, and the removal rate of xylene is greater than 40.7%. The OD600 value of the microorganism after cultivation is greater than 1.55, which shows that the composite slow-release material prepared in the present application can effectively enhance the metabolism of organisms, synergize with microorganisms, and improve the ability of groundwater remediation.

[0061] As can be seen from 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 is adjusted in Examples 5 and 6, and polyvinyl alcohol is not added in Example 7. Compared with Example 3, the pollutant degradation performance of Examples 5 and 6 is reduced; this is because the components and proportions of the inner wall material affect the stability of the inner wall material, which affects the release of the composite oxidant, and further affects the synergistic effect with microorganisms, thereby reducing the pollutant degradation performance.

[0062] As can be seen from Table 1, the only difference between Examples 8, 9, and 10 and Example 3 is that the composition ratio of the outer wall material is adjusted in Examples 8 and 9, and peptone is not added in Example 9. Compared with Example 3, the degradation ability of pollutants in Examples 8, 9, and 10 is reduced; this is because the components and proportions of the outer wall material affect the overall stability of the composite sustained-release material, the adsorption performance of pollutants and the promotion of microbial growth are reduced, the oxidation performance and the synergistic effect with microorganisms are reduced, and thus the pollutant degradation performance is reduced.

[0063] As can be seen from Table 1, the only difference between Comparative Examples 1, 2, and 3 and Example 3 is that: in Comparative Example 1, the composite oxidant is replaced by calcium peroxide, in Comparative Example 2, the self-Fenton mesoporous titanium dioxide is replaced by mesoporous titanium dioxide, and in Comparative Example 3, the self-Fenton mesoporous titanium dioxide is replaced by an ethylenediaminetetraacetic acid iron complex. Compared with Example 3, the degradation performance of pollutants in Comparative Examples 1, 2, and 3 is significantly reduced; this is because the composite oxidant is replaced by calcium peroxide, and the single calcium peroxide lacks synergistic effect, the oxidative degradation performance is reduced, and the promoting effect on the self-Fenton system is reduced; when the self-Fenton mesoporous titanium dioxide is replaced by a single mesoporous titanium dioxide or an iron-based complex, the self-Fenton system is affected, the stability is reduced, and the catalytic degradation performance is reduced, thereby significantly reducing the degradation performance of pollutants and reducing the repair effect.

[0064] This specific embodiment is only an explanation of the present application, and it is not a limitation of the present application. Through the above description, relevant staff can make various changes and modifications without deviating from the technical idea of ​​the present application. The technical scope of the present application is not limited to the content in the specification, and its technical scope 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: Composite oxidant 20-40 parts 30-50 pieces of inner wall material Glucose 10-20 parts 40-60 pieces of outer wall material 5-15 parts of self-Fenton mesoporous titanium dioxide.

2. A composite slow-release material for groundwater remediation according to claim 1, characterized in that: The raw materials for preparing the self-Fenton mesoporous titanium dioxide include a mesoporous titanium dioxide body and an iron-based complex.

3. A composite slow-release material for groundwater remediation according to claim 2, characterized in that: The iron-based complex includes ethylenediaminetetraacetic acid iron complex.

4. The composite slow-release material for groundwater remediation according to claim 1, characterized in that: The composite oxidant includes calcium peroxide and sodium persulfate.

5. The composite slow-release material for groundwater remediation according to claim 1, characterized in that: The inner wall material comprises chitosan, polyvinyl alcohol and a cross-linking agent.

6. The composite slow-release material for groundwater remediation according to claim 5, characterized in that: The mass ratio of chitosan, polyvinyl alcohol and cross-linking agent is (3-5): (5-7): 0.

3.

7. A composite slow-release material for groundwater remediation according to claim 6, characterized in that: The cross-linking agent includes one of genipin and maleic anhydride.

8. The composite slow-release material for groundwater remediation according to claim 1, characterized in that: The outer wall material comprises starch, peptone and carbodiimide.

9. A composite slow-release material for groundwater remediation according to claim 8, characterized in that: The mass ratio of the starch, peptone and carbodiimide is (6-7): (2-3):

1.

10. A process for preparing a composite slow-release material for groundwater remediation as claimed in any one of claims 1 to 9, characterized in that: The steps include: Add chitosan to glacial acetic acid solution and stir to obtain chitosan solution; add polyvinyl alcohol to water and stir to obtain polyvinyl alcohol solution; disperse the composite oxidant in water and obtain a mixed solution after ultrasonic treatment; add the mixed solution to polyvinyl alcohol solution and stir to obtain an emulsion, and ultrasonicate the emulsion to obtain a refined emulsion; add the chitosan solution to the refined emulsion and stir to obtain a mixed emulsion; dissolve genipin in water to obtain a crosslinker solution, add the crosslinker solution to the mixed emulsion, adjust the pH to acidic, stir the reaction, centrifuge, wash with water, and vacuum dry to obtain inner layer microcapsules; The starch is dispersed in water, heated and stirred to obtain a starch solution; peptone is dissolved in water, stirred to obtain a peptone solution; the peptone solution is added to the starch solution, stirred to obtain a mixed outer wall material emulsion; the inner layer microcapsules, glucose and self-Fenton mesoporous titanium dioxide prepared above are added to the mixed outer wall material emulsion, stirred to obtain a mixed suspension, the pH of the mixed suspension is adjusted to acidic, a carbodiimide aqueous solution is added, stirred while adding, and a product suspension is obtained after reaction; the product suspension is centrifuged, washed with water and then vacuum dried to obtain a composite sustained-release material.

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