Slow-release soil remediation agent and application thereof in remediation of oil-containing soil
By introducing hyperbranched nano-active materials and composite oxidants into soil remediation agents, the problem of poor performance of traditional soil remediation agents under neutral or alkaline conditions has been solved. This has achieved efficient and long-lasting soil remediation effects over a wide pH range, reducing equipment costs and minimizing pollutant rebound.
Patent Information
- Application Number
- CN202511163734.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-19
- Publication Date
- 2025-12-02
AI Technical Summary
Existing chemical oxidants in soil remediation suffer from price fluctuations, pollution risks, pH dependence, and efficiency issues during the treatment process. Traditional Fenton reagents are ineffective under neutral or alkaline conditions and also suffer from high equipment costs, uneven remediation, and problems such as back diffusion of pollutants and concentration rebound.
The use of hyperbranched nanomaterials enhances the soil remediation agent. By introducing a heterogeneous catalyst, the slow-release problem of the soil remediation agent is solved, the applicable pH range is broadened, the remediation effect is improved, and pollutant rebound and concentration tailing are reduced.
It achieves efficient soil remediation over a wide pH range, reduces equipment costs, avoids secondary pollution, improves remediation depth and durability, and solves the problems of high equipment costs and pollutant rebound associated with traditional oxidants.
Smart Images
Figure CN121046091A_ABST
Abstract
Description
Technical Field
[0001] This application relates to a slow-release soil remediation agent and its application in the remediation of oily soils, belonging to the field of soil remediation. Background Technology
[0002] Currently, the chemical oxidants used in the market are mostly potassium permanganate, sodium persulfate, and Fenton peroxide. These products have undergone long-term research both domestically and internationally, and their oxidation mechanisms are relatively clear, with stable effects. However, in recent years, due to fluctuations in international and domestic chemical raw material prices and production capacity adjustments by manufacturers, the prices of most chemical oxidants, such as potassium permanganate, sodium persulfate, and hydrogen peroxide, have increased significantly, and safety regulations for their production, transportation, and use have become increasingly stringent. Furthermore, these oxidants can still cause secondary pollution after use, affecting the pH of soil and groundwater.
[0003] Traditional Fenton's reagent refers to an oxidation system composed of ferrous salts and hydrogen peroxide (H2O2 / Fe). 2+ When hydrogen peroxide and ferrous salts are mixed, the hydrogen peroxide releases a large number of hydroxyl radicals under the catalysis of ferrous iron. Hydroxyl radicals are highly effective non-selective oxidants, making this system extremely effective at oxidizing organic pollutants. It is often used as an advanced oxidation technology in water treatment. With the development of the soil remediation industry, it is increasingly being applied to soil site remediation.
[0004] Traditional Fenton's reagent is highly effective at oxidizing organic matter under acidic conditions. Ojinnaka et al. used traditional Fenton's reagent to remediate artificially contaminated sand and compared its remediation effects under acidic, neutral, and alkaline conditions. The results showed that the degradation effect of oil pollution was best under acidic conditions. Soil mineral composition affects the remediation effect of Fenton's reagent: in soils rich in iron minerals, high removal rates can be achieved even without adding soluble iron, while adding soluble iron is essential in soils with low iron mineral content. Soil type also affects the effectiveness of Fenton's reagent; its removal effect in clay (20% removal) is far less than in loam (80% removal). Furthermore, the use of Fenton's reagent can lead to the downward leaching of benzene compounds (BTEX), thus posing a risk of groundwater contamination. Although traditional Fenton's reagent can play a role in soil remediation, it still has many drawbacks, such as demanding pH requirements, significant heat release, and poor remediation efficacy.
[0005] Meanwhile, in in-situ remediation, existing chemical oxidants also suffer from the problem of rapidly decreasing effectiveness with increasing treatment depth, and the remediation site experiencing back diffusion and concentration rebound of pollutants a few days or even a few hours after the in-situ remediation stops. Therefore, they lack long-term remediation effects. Summary of the Invention
[0006] Addressing the shortcomings of existing technologies, the soil chemical remediation system of this invention improves remediation effectiveness while being non-toxic and having no side effects. It is applicable across a wide pH range and is suitable not only for organically contaminated soil and groundwater but also for surface water, municipal wastewater, polluted river sediment, waste sludge, and oily sludge. Furthermore, the use of slow-release materials allows for more sustained in-situ treatment of contaminated soil. In-situ chemical oxidation, centered on slow-release materials, controls the release of active compounds, reduces non-selective consumption of oxidants, improves pollutant removal efficiency, and maintains remediation effects for months or even years, rather than just a short period.
[0007] According to a first aspect of this application, a slow-release soil remediation agent is provided. The soil remediation system of this invention incorporates hyperbranched nanomaterials into a traditional oxidation system, enhancing the soil remediation effect while ensuring strong oxidizing properties without damaging soil properties. It exhibits good remediation effects over a wide pH range. The slow-release system of the soil remediation agent enhances the depth of in-situ remediation and addresses issues such as backdiffusion, concentration tailing, and pollutant rebound.
[0008] A slow-release soil remediation agent, the slow-release soil remediation agent comprising a composite oxidant, hyperbranched nano-active materials, cement, bentonite and water;
[0009] The composite oxidant includes ferrous sulfate, sodium percarbonate, and Fe-based covalent framework materials;
[0010] The hyperbranched nano-active material is a hyperbranched nano-silica material.
[0011] Optionally, the weight parts of each component in the slow-release soil remediation agent are as follows:
[0012]
[0013] Optionally, the weight parts of each component in the composite oxidant are as follows:
[0014] 20-42 parts by weight of ferrous sulfate
[0015] Sodium percarbonate 30-54 parts by weight
[0016] 26–50 parts by weight of Fe-based covalent framework material.
[0017] Optionally, the Fe-based covalent framework material is MIL-100(Fe).
[0018] Compared to commonly used soil remediation agents, this system successfully overcomes the core limitation of homogeneous iron ion precipitation and deactivation under neutral / alkaline conditions by introducing the heterogeneous catalyst MIL-100 (Fe) and utilizing carbonate buffer solution generated from the decomposition of sodium percarbonate. It also automatically adjusts and stabilizes the reaction environment within the neutral to weakly alkaline range, where heterogeneous catalysis is highly efficient. Therefore, its pH range (especially towards neutral / alkaline conditions) is significantly wider than that of the traditional Fenton system and Fe... 2+ The / PS system has been significantly broadened. Therefore, this system has greater practical application potential in treating pollutants in soils with natural pH (usually neutral or slightly alkaline), reducing reliance on strong acid regulation and associated costs and environmental risks.
[0019] This system utilizes hyperbranched nanomaterials. The enormous specific surface area of these materials provides numerous exposed reaction sites, while the abundant terminal functional groups allow for targeted binding with different pollutants, significantly enhancing the material's adsorption capacity and selectivity. Like a miniature "sponge" filled with hooks, it effectively captures pollutant molecules or ions. Simultaneously, the hyperbranched structure serves as an ideal catalyst support platform; its internal cavities and surface functional groups can anchor and stabilize metal nanoparticles, maintaining their high activity and stability.
[0020] Optionally, the preparation method of the hyperbranched nano-active material includes:
[0021] S1 reacts the alcohol amine and acid anhydride I to obtain solution A;
[0022] S2. Orthosilicate is added dropwise to a mixed solution containing water, ethanol, and ammonia. Reaction II is carried out to obtain a nano-silica dispersion, denoted as solution B.
[0023] Under the protection of an inactive gas, S3 mixes solution A and solution B, adds a catalyst, and refluxes reaction III to obtain the hyperbranched nano-active material.
[0024] Optionally, in step S1, the alkanolamine is selected from at least one of diethanolamine, diisopropanolamine, and triethanolamine;
[0025] The anhydride is selected from at least one of maleic anhydride, succinic anhydride, and hexahydrophthalic anhydride.
[0026] Optionally, the mass ratio of the alkanolamine to the acid anhydride is 1-1.5:1-2.
[0027] Optionally, the temperature of reaction I is 70–90°C, and the reaction time is 0.3–2 h.
[0028] Optionally, in step S2, at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate is used.
[0029] Optionally, in the mixed solution, the mass ratio of water, ethanol, and ammonia is 15–26:40–62:3–8.
[0030] Optionally, the mass ratio of the orthosilicate to the mixed solution is 1:12 to 18.
[0031] Optionally, the temperature of reaction II is 20–35°C, and the reaction time is 2–8 h.
[0032] Optionally, in step S3, the ratio of the amount of solution A to solution B is 1-2.5:5-8.
[0033] Optionally, the catalyst is selected from at least one of p-toluenesulfonic acid and sulfuric acid.
[0034] Optionally, the temperature of reaction III is 100–120°C, and the reaction time is 4–8 h.
[0035] As a preferred embodiment, the preparation method of the hyperbranched nano-active material includes:
[0036] S1 First, preheat 20-30g of one of diethanolamine, diisopropanolamine, and triethanolamine at 70℃ for 0.5h, then slowly add 20-40g of one of maleic anhydride, succinic anhydride, and hexahydrophthalic anhydride, and react at 80℃ for 0.5h to obtain solution A.
[0037] S2 mixes 23g water, 50g ethanol and 4g ammonia water and stirs them evenly. Then slowly add 5g tetraethyl orthosilicate and react at 25℃ for 3h to obtain a nano silica dispersion, i.e., solution B.
[0038] Under nitrogen protection, solution A and solution B are mixed, and 0.5-1g of either p-toluenesulfonic acid or sulfuric acid is added. The mixture is then refluxed at 100°C for 6 hours to obtain the hyperbranched nano-active material.
[0039] As one specific implementation method, the preparation method of the hyperbranched nano-active material includes:
[0040] S1. First, preheat 25g of diethanolamine at 70℃ for 0.5h, then slowly add 28g of maleic anhydride, and react at 80℃ for 0.5h to obtain solution A;
[0041] S2. Mix 23g water, 50g ethanol and 4g ammonia water and stir well. Slowly add 5g tetraethyl orthosilicate and react at 25℃ for 3h to obtain nano silica dispersion, i.e. solution B.
[0042] S3. Under nitrogen protection, solution A and solution B are mixed, 0.8 g of p-toluenesulfonic acid is added, and the mixture is refluxed at 100 °C for 6 h to obtain the hyperbranched nano-active material.
[0043] The structural formula of the product obtained in step S1 is as follows:
[0044]
[0045] The structural formula of the product obtained in step S2 is as follows:
[0046]
[0047] The structural formula of the product obtained in step S3 is as follows:
[0048]
[0049] According to a second aspect of this application, a method for preparing a slow-release soil remediation agent is provided.
[0050] The preparation method of the slow-release soil remediation agent described above involves mixing the composite oxidant, hyperbranched nano-active material, cement, and bentonite powder evenly, adding water, stirring to make them completely mixed, adding the mixture into a mold, compacting it, and then directly opening the mold to obtain the slow-release soil remediation agent.
[0051] According to a third aspect of this application, an application of a slow-release soil remediation agent is provided.
[0052] The application of the slow-release soil remediation agent described above in the remediation of oily soils.
[0053] The beneficial effects that this application can produce include:
[0054] The slow-release soil remediation agent and its application in oily soil remediation provided in this application have a wide applicable pH range; the addition of hyperbranched nano-active materials enhances the soil remediation effect; and since it does not contain strong oxidants such as Fenton and persulfate, there is no subsequent pollution; compared with traditional soil remediation systems, the cost is lower. The slow-release system of the soil remediation agent can improve the depth of in-situ remediation while solving problems such as back diffusion, concentration tailing, and pollutant rebound. Attached Figure Description
[0055] Figure 1 Photos of the soil remediation process;
[0056] Figure 2 Photos of the soil remediation process;
[0057] Figure 3 Photo of soil sample No. 1;
[0058] Figure 4 Photos of soil No. 1 before (left) and after (right) remediation;
[0059] Figure 5 Photograph of soil type 2;
[0060] Figure 6 Photos of soil No. 2 before (left) and after (right) remediation. Detailed Implementation
[0061] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0062] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0063] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.
[0064] Example 1
[0065] Preparation of composite oxidant: It is made by combining ferrous sulfate, sodium percarbonate and Fe-based covalent framework material MIL-100(Fe). The specific process is to mix 3g of ferrous sulfate, 3.6g of sodium percarbonate and 3.4g of Fe-based covalent framework material MIL-100(Fe) evenly to obtain composite oxidant.
[0066] Preparation of hyperbranched nano-active materials: S1. First, preheat 25g of diethanolamine at 70℃ for 0.5h, then slowly add 28g of maleic anhydride, and react at 80℃ for 0.5h to obtain solution A;
[0067] S2. Mix 23g water, 50g ethanol and 4g ammonia water and stir well. Slowly add 5g tetraethyl orthosilicate and react at 25℃ for 3h to obtain nano silica dispersion, i.e. solution B.
[0068] S3. Under nitrogen protection, solution A and solution B are mixed, 0.8 g of p-toluenesulfonic acid is added, and the mixture is refluxed at 100 °C for 6 h to obtain the hyperbranched nano-active material.
[0069] Example 2
[0070] The procedure is the same as in Example 1, except that the composite oxidant is prepared.
[0071] Preparation of composite oxidant: It is made by combining ferrous sulfate, sodium percarbonate and Fe-based covalent framework material MIL-100(Fe). The specific process is to mix 2.5g of ferrous sulfate, 3.2g of sodium percarbonate and 2.8g of Fe-based covalent framework material MIL-100(Fe) evenly to obtain composite oxidant.
[0072] Example 3
[0073] The procedure is the same as in Example 1, except that hyperbranched nano-active materials are prepared.
[0074] Preparation of hyperbranched nano-active materials: S1. First, preheat 25g of diethanolamine at 70℃ for 0.5h, then slowly add 35g of maleic anhydride, and react at 80℃ for 1.5h to obtain solution A;
[0075] S2. Mix 23g water, 50g ethanol and 4g ammonia water and stir well. Slowly add 5.5g tetraethyl orthosilicate and react at 25℃ for 5h to obtain nano silica dispersion, i.e. solution B.
[0076] S3. Under nitrogen protection, solution A and solution B are mixed, 0.8 g of p-toluenesulfonic acid is added, and the mixture is refluxed at 100 °C for 6 h to obtain the hyperbranched nano-active material.
[0077] Example 4: Slow-release soil remediation agent
[0078] Weigh 10g of composite oxidant, 5g of hyperbranched nano-active material, 7g of cement, and 2.4g of bentonite, add them to a beaker, mix the powders evenly, add 4mL of water, stir for 10 minutes to make them completely mixed, pour the mixture into a mold, compact it, and then open the mold directly to obtain a spherical slow-release soil remediation agent.
[0079] The slow-release soil remediation agent obtained using the composite oxidant and hyperbranched nano-active material prepared in Example 1 is designated as Sample 1#.
[0080] The slow-release soil remediation agent obtained using the composite oxidant and hyperbranched nano-active material prepared in Example 2 is designated as Sample 2#.
[0081] The slow-release soil remediation agent obtained using the composite oxidant and hyperbranched nano-active material prepared in Example 3 is designated as Sample 3#.
[0082] Example 5: Slow-release soil remediation agent
[0083] Weigh 10g of composite oxidant, 6g of hyperbranched nano-active material, 8g of cement, and 3g of bentonite, add them to a beaker, mix the powders evenly, add 5mL of water, stir for 10 minutes to make them completely mixed, pour the mixture into a mold, compact it, and then open the mold directly to obtain a spherical slow-release soil remediation agent.
[0084] The slow-release soil remediation agent obtained using the composite oxidant and hyperbranched nano-active material prepared in Example 1 is designated as Sample 4#.
[0085] The slow-release soil remediation agent obtained using the composite oxidant and hyperbranched nano-active material prepared in Example 2 is designated as Sample 5#.
[0086] The slow-release soil remediation agent obtained using the composite oxidant and hyperbranched nano-active material prepared in Example 3 is designated as Sample 6#.
[0087] Application in oil-bearing soil remediation
[0088] Taking slow-release soil remediation agent sample 1# as an example, take an appropriate amount of soil (100g) into a petri dish, weigh out 6g of slow-release soil remediation agent and add it to the soil. Stir manually to ensure that the soil and slow-release soil remediation agent are in full contact. Stir manually again, add 50g of water, and finally stir evenly. Place it in a natural environment. With 1 day as the basic unit of maintenance, take the remediated soil every day and place it in an oven at 105℃. Use an infrared oil meter to test the oil content of the soil regularly. After the remediation is completed, take samples for testing every 30 days.
[0089] Using the Fenton system (hydrogen peroxide, ferrous sulfate) as a control, the specific process of the Fenton system (hydrogen peroxide, ferrous sulfate) is as follows: Take an appropriate amount of soil (100g) into a petri dish, weigh out 3g of ferrous sulfate and 3g of hydrogen peroxide and add them to the soil. Stir manually to ensure that the soil and the agent are in full contact. Stir manually again, add 50g of water, and finally stir evenly. Place the dish in a natural environment. With 1 day as the basic unit of maintenance, take the repaired soil every day and place it in an oven at 105℃. Use an infrared oil analyzer to test the oil content of the soil regularly. After the repair is completed, take samples for testing every 30 days.
[0090] Photos of the soil remediation process, such as Figure 1 This represents the state of the soil after all the pesticides have been added. Figure 2 This is the state of the repair process under sunlight.
[0091] Soil remediation experiment results:
[0092] (1) Soil No. 1
[0093] Original soil properties
[0094] sample Original moisture content % Original solids content % Original oil content (after removing water) % Soil No. 1 12.77 80.82 7.35
[0095] Experimental results
[0096]
[0097] Figure 3 This is a photo of soil sample number 1. Figure 4 The photos show soil No. 1 before (left) and after (right) remediation. It can be seen that after 10 days of remediation, the color of soil No. 1 changed from black to brown, and the oil content was significantly reduced.
[0098] Conclusion: After 13 days of remediation with this system's agents, the oil content of the soil decreased from the original 7.35% to 0.28%, meeting the requirement of most standards being less than 0.3%. After remediation, samples were taken every 30 days, and the oil content did not rebound; instead, due to the slow-release characteristics of the remediation agent, the oil content continued to decrease to 0.13%. While the Fenton system also reduced the oil content, the remediation speed was slower, and rebound phenomena were observed after a long period. Overall, the remediation effect was not as good as that of this system's agents.
[0099] (2) Soil No. 2
[0100] Original soil properties
[0101] sample Original moisture content % Original solids content % Original oil content (after removing water) % Soil No. 2 24.69％ 70.04％ 7.00％
[0102] Experimental results
[0103]
[0104] Figure 5 This is a photo of soil sample number 2. Figure 6 The photos show soil No. 2 before (left) and after (right) remediation. It can be seen that after 10 days of remediation, the soil No. 2 changed from a viscous state to a loose state, and a large amount of black petroleum hydrocarbons were removed.
[0105] Conclusion: After 10 days of remediation with this system's agents, the oil content of the soil decreased from the original 7.00% to 0.15%, meeting the requirement of less than 0.3% in most standards. After remediation, samples were taken every 30 days, and the oil content did not rebound; instead, due to the slow-release characteristics of the remediation agent, the oil content continued to decrease to 0.04%. While the Fenton system also reduced the oil content, the remediation speed was slower, and rebound phenomena were observed after a long period. Overall, the remediation effect was not as good as that of this system's agents.
[0106] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A slow-release soil remediation agent, characterized in that, The slow-release soil remediation agent comprises a composite oxidant, hyperbranched nano-active materials, cement, bentonite, and water; The composite oxidant includes ferrous sulfate, sodium percarbonate, and Fe-based covalent framework materials; The hyperbranched nano-active material is a hyperbranched nano-silica material.
2. The slow-release soil remediation agent according to claim 1, characterized in that, The weight parts of each component in the slow-release soil remediation agent are as follows:
3. The slow-release soil remediation agent according to claim 1, characterized in that, The weight parts of each component in the composite oxidant are as follows: 22-42 parts by weight of ferrous sulfate Sodium percarbonate 30-54 parts by weight 26–50 parts by weight of Fe-based covalent framework material.
4. The slow-release soil remediation agent according to claim 1, characterized in that, The Fe-based covalent framework material is MIL-100(Fe).
5. The slow-release soil remediation agent according to claim 1, characterized in that, The preparation method of the hyperbranched nano-active material includes: S1 reacts the alcohol amine and acid anhydride I to obtain solution A; S2. Orthosilicate is added dropwise to a mixed solution containing water, ethanol, and ammonia. Reaction II is carried out to obtain a nano-silica dispersion, denoted as solution B. Under the protection of an inactive gas, S3 mixes solution A and solution B, adds a catalyst, and refluxes reaction III to obtain the hyperbranched nano-active material.
6. The slow-release soil remediation agent according to claim 5, characterized in that, In step S1, the alkanolamine is selected from at least one of diethanolamine, diisopropanolamine, and triethanolamine; The acid anhydride is selected from at least one of maleic anhydride, succinic anhydride, and hexahydrophthalic anhydride; Preferably, the mass ratio of the alkanolamine to the acid anhydride is 1-1.5:1-2; Preferably, the temperature of reaction I is 70–90°C, and the reaction time is 0.3–2 h.
7. The slow-release soil remediation agent according to claim 5, characterized in that, In step S2, at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate is used. Preferably, in the mixed solution, the mass ratio of water, ethanol, and ammonia is 15–26:40–62:3–8; Preferably, the mass ratio of the orthosilicate to the mixed solution is 1:12 to 18; Preferably, the temperature of reaction II is 20–35°C, and the reaction time is 2–8 h.
8. The slow-release soil remediation agent according to claim 5, characterized in that, In step S3, the ratio of the amount of solution A to solution B is 1-2.5:5-8; Preferably, the catalyst is selected from at least one of p-toluenesulfonic acid and sulfuric acid; Preferably, the temperature of reaction III is 100–120°C, and the reaction time is 4–8 h.
9. A method for preparing the slow-release soil remediation agent according to any one of claims 1 to 8, characterized in that, After the composite oxidant, hyperbranched nano-active material, cement, and bentonite powder are mixed evenly, water is added and stirred until completely mixed. The mixture is then poured into a mold, compacted, and the mold is opened directly to obtain the slow-release soil remediation agent.
10. The application of the slow-release soil remediation agent according to any one of claims 1 to 8 in the remediation of oily soil.