Soil pollution remediation material, preparation method thereof and soil pollution remediation method

Abstract

The invention discloses a soil pollution remediation material, a preparation method thereof and a soil pollution remediation method, relates to the technical field of soil pollution remediation, breaks through the bottleneck of a traditional remediation technology, and realizes rapid and deep remediation of various kinds of contaminated soil. Comprising the following components in parts by mass: 40-60 parts of granulated blast furnace slag, 15-25 parts of fly ash, 10-20 parts of desulfurized gypsum, 3-5 parts of an exciting agent and 1-3 parts of a nano additive, the exciting agent is prepared from high-alumina cement, quick lime and anhydrous sodium silicate according to the mass ratio of 1: 1: 1; the nano additive is titanium dioxide / activated carbon nano composite particles, and the mass ratio of titanium dioxide to activated carbon is (1: 9)-(1: 4). The method can be applied to rapid and deep remediation of various kinds of contaminated soil.

Description

Technical Field

[0001] This invention relates to the field of soil pollution remediation technology, specifically to a soil pollution remediation material and its preparation method, as well as a soil pollution remediation method. Background Technology

[0002] Currently, soil pollution has become a global environmental concern, seriously threatening ecological balance, food safety, and human health. While traditional soil remediation technologies, such as solidification / stabilization, can immobilize pollutants to some extent and reduce their mobility and bioavailability, they cannot truly degrade pollutants, posing long-term environmental risks. Specifically, traditional remediation technologies typically use materials like cement and lime to fix heavy metals in the soil; however, these heavy metals remain in the soil and may be released again over time when environmental conditions change, causing secondary pollution. Bioremediation, on the other hand, relies on the growth and metabolic activities of microorganisms to degrade pollutants, requiring stringent environmental conditions such as soil pH, temperature, humidity, and pollutant toxicity. When the soil pH deviates from the optimal growth range for microorganisms, or when the temperature is too high or too low, microbial activity is inhibited or even kills, leading to poor remediation results. Moreover, for some high-concentration, recalcitrant pollutants, microbial remediation efficiency is extremely low, failing to meet practical remediation needs.

[0003] To address the aforementioned issues, this invention aims to develop a novel soil pollution remediation material and its supporting technologies. By eliminating reliance on microorganisms and utilizing the synergistic effects of chemical activation and nanocatalysis, a highly efficient, stable, and adaptable soil remediation system is constructed. This system aims to overcome the bottlenecks of traditional remediation technologies and achieve rapid and in-depth remediation of various types of polluted soils. Summary of the Invention

[0004] To address the above technical problems, this invention proposes a soil pollution remediation material, its preparation method, and a soil pollution remediation method.

[0005] The specific technical solution of the present invention is as follows: This invention provides a soil pollution remediation material, comprising the following components in parts by weight: Granulated blast furnace slag 40-60 parts, fly ash 15-25 parts, desulfurized gypsum 10-20 parts, activator 3-5 parts, nano-additive 1-3 parts; The activator is composed of high-alumina cement, quicklime, and anhydrous sodium silicate in a mass ratio of 1:1:1; The nano-additive is titanium dioxide / activated carbon nanocomposite particles, and the mass ratio of titanium dioxide to activated carbon is 1:9 to 1:4.

[0006] Preferably, the titanium dioxide / activated carbon nanocomposite particles are obtained through the following steps: Mix tetrabutyl titanate and anhydrous ethanol at a volume ratio of 1:4 and stir magnetically for 10 minutes; adjust the pH to 2-3 by adding dilute nitric acid dropwise, slowly add deionized water and continue stirring until a transparent sol is formed. Dry nano-sized activated carbon was added to the sol and ultrasonically dispersed evenly. Subsequently, the mixture was stirred and evaporated into a paste under a water bath at 60°C, then transferred to a muffle furnace and calcined at 450°C for 2 hours. After cooling, it was ground through a 200-mesh sieve to obtain composite particles.

[0007] Preferably, the component comprises the following parts by mass: 50 parts granulated blast furnace slag, 20 parts fly ash, 18 parts desulfurized gypsum, 4 parts activator, and 2 parts nano-additives.

[0008] The present invention also provides a method for preparing the above-mentioned soil pollution remediation material, comprising the following steps: S1. After mixing granulated blast furnace slag, fly ash, desulfurization gypsum, and activator, the mixture is first coarsely ground, then finely ground until the specific surface area is greater than 650 m². 2 / kg, to obtain composite powder; S2. Place the nano-additive in a high-speed disperser, add deionized water as the dispersion medium, and pre-disperse to form a uniform nano-suspension. S3. Spray the nano suspension evenly into the above composite powder in 3 to 5 batches through a dual-fluid atomizing nozzle; S4. The mixed material is vacuum dried to remove surface free moisture, and then passed through a 100-mesh sieve to obtain soil pollution remediation material.

[0009] Preferably, both the coarse grinding and fine grinding in step S1 are performed using a vertical planetary mill, and the temperature throughout the grinding process does not exceed 40°C.

[0010] Preferably, the coarse grinding in step S1 is performed at a speed of 1200~1500 rpm for 10~15 min.

[0011] Preferably, the grinding media used in step S1 is zirconia beads, and the rotation speed is 2000~2200 rpm.

[0012] Preferably, the pre-dispersion speed in step S2 is 3000~3500 rpm, and the time is 5~8 min.

[0013] The present invention also provides a method for soil pollution remediation, which involves applying the above-mentioned soil pollution remediation materials for remediation. The remediation method includes the following steps: First, mix the soil pollution remediation material with the polluted soil at a mass ratio of 1:10~20. Then, adjust the soil moisture content to 25~35%. At room temperature, till the soil to a depth of 10~15cm every 2~3 days and continue to maintain it for 7~15 days to achieve the degradation and remediation of pollutants in the soil.

[0014] Compared with the prior art, the specific beneficial effects of the present invention are as follows: 1. This invention utilizes the synergistic effect of activators to create a slightly alkaline environment. Quicklime reacts with soil and moisture generated during the preparation process to generate Ca(OH)2. Combined with the hydration reaction of high-alumina cement and anhydrous sodium silicate, the pH of the remediation system is stabilized at 10-12. This environment can disrupt the long-chain or cyclic structures of organic compounds such as petroleum hydrocarbons and polycyclic aromatic hydrocarbons, promoting their hydrolysis and transformation into easily catalytically degradable small-molecule intermediates. Titanium dioxide / activated carbon composite particles act as an auxiliary agent, playing a core catalytic role in this process. Their high specific surface area rapidly adsorbs and enriches hydrolyzed small-molecule pollutants on the particle surface. Under ambient light irradiation, titanium dioxide's valence band electrons are excited to the conduction band, forming electron-hole pairs. These holes combine with surface hydroxyl groups to generate hydroxyl radicals with high oxidation potential, which can non-selectively attack organic molecules, mineralizing them into harmless substances such as CO2 and H2O, achieving efficient and synergistic degradation of contaminated soil.

[0015] 2. In this invention, CaO and Al2O3 in the slag undergo a hydration reaction with SiO2 in the fly ash, generating a large amount of CSH gel, ettringite, and hydrated calcium aluminate, etc., with surfaces rich in active sites such as hydroxyl groups and calcium ions. Calcium ions can react with Pb in the soil. 2+ Cd 2+ During gelation, heavy metal ions undergo ion exchange, anchoring them within the gel lattice through charge balance. Simultaneously, hydroxyl groups form stable complexes with heavy metal ions, further reducing their migration activity. Furthermore, the dense network structure formed by the gel products physically encapsulates the heavy metal ions, preventing their leaching by rainwater or migration through soil pore water.

[0016] 3. This invention achieves remediation through a purely physical-chemical mechanism, exhibiting broad environmental adaptability and high efficiency. In traditional bioremediation, microbial activity is easily affected by pH, salinity, etc., while the gelation reaction and nanocatalytic reaction of this invention are both chemical processes, which can be stably carried out in complex environments such as acidic mining soils, alkaline saline-alkali soils, and high-salt soils. Attached Figure Description

[0017] Figure 1 Here is a SEM image of the nano-additive in Example 1; Figure 2 This is an SEM image of the hydration products of the repair material in Example 1. Detailed Implementation

[0018] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0019] Example 1. The formula in this embodiment includes: 50g granulated blast furnace slag, 20g fly ash, 18g desulfurized gypsum, 4g activator (1.33g high-alumina cement, 1.33g quicklime, 1.34g anhydrous sodium silicate), and 2g nano-additives.

[0020] First, tetrabutyl titanate and anhydrous ethanol were mixed at a volume ratio of 1:4 and magnetically stirred for 10 minutes. Dilute nitric acid was added dropwise to adjust the pH to 2-3. Deionized water was slowly added and stirred continuously until a transparent sol was formed. Dry nano-sized activated carbon was added to the sol and ultrasonically dispersed evenly. Then, it was stirred and evaporated into a paste under a water bath at 60°C. The paste was then transferred to a muffle furnace and calcined at 450°C for 2 hours. After cooling, it was ground through a 200-mesh sieve to obtain the composite particle nano-auxiliary agent.

[0021] Scanning electron microscopy was used to analyze the nano-adjuvants, and the results were obtained. Figure 1 Activated carbon is porous and has a high specific surface area. When titanium dioxide particles are loaded on its surface, they tend to agglomerate due to adsorption, forming dense particle aggregates. This morphology gives it both an ultra-large specific surface area and photocatalytic active sites. It can first adsorb and enrich organic pollutants such as petroleum hydrocarbons and polycyclic aromatic hydrocarbons, and then non-selectively mineralize them into harmless substances through photocatalytic reactions, achieving synergistic degradation.

[0022] The specific preparation process of the repair material is as follows: S1. Mix the above formula using a 250mL vertical planetary mill. Grind at 1300rpm for 12 minutes at 35℃. Then add 1.0mm zirconia beads and grind at 2100rpm for 38 minutes. The resulting composite powder has a specific surface area of ​​685m². 2 / kg; S2, nano-additives, and 0.12g of deionized water were added and dispersed at 3200rpm for 6min to form a suspension; S3. Spray in 4 batches using atomized spraying and magnetic mixing; S4, vacuum dried at 55℃ for 1.5h, and 92g of repair material was obtained by passing through a 100-mesh sieve.

[0023] Mix 1.38 kg of petroleum hydrocarbon-contaminated soil with 92 g of remediation material, adjust the moisture content to 25%, till 12 cm every 2 days at 25℃, and maintain for 10 days.

[0024] The repair material prepared in this embodiment was subjected to SEM testing, and the results are shown in the figure. Figure 2The material exhibits a fibrous and flocculent morphology, with the flocculent regions being characteristic products of the activator after activating the cementitious material. Theoretically, the dense network structure provides physical strength to the material, preventing particle loss during the remediation process; furthermore, its abundant hydroxyl and calcium ion sites on the surface can fix heavy metals in the soil through ion exchange and complexation.

[0025] Example 2. The formula in this embodiment includes: 45g of granulated blast furnace slag, 25g of fly ash, 15g of desulfurized gypsum, 5g of activator (1.67g of high-alumina cement, 1.67g of quicklime, 1.66g of anhydrous sodium silicate), and 1g of nano-additives.

[0026] The preparation process is as follows: S1. Mix the above formula using a 250mL vertical planetary mill. Coarsely grind at 1200rpm for 15 minutes at 38℃. Then add 0.8mm zirconia beads and finely grind at 2000rpm for 45 minutes. The resulting composite powder has a specific surface area of ​​660m². 2 / kg; S2, add 0.05g of deionized water to the nano-additive and disperse at 3000rpm for 8min to form a suspension; S3. Spray in 3 batches using atomized spraying and magnetic mixing; S4, vacuum dried at 50℃ for 2 hours, and 86g of repair material was obtained by passing through a 100-mesh sieve.

[0027] Mix 860g of heavy metal contaminated soil with 86g of remediation material, adjust the moisture content to 30%, till 15cm every 3 days at 30℃, and cure for 7 days.

[0028] Example 3. The formula in this embodiment includes: 60g granulated blast furnace slag, 15g fly ash, 17g desulfurized gypsum, 3g activator (1.0g high-alumina cement, 1.0g quicklime, 1.0g anhydrous sodium silicate), and 3g nano-additives.

[0029] The preparation process is as follows: S1. Mix the above formula using a 250mL vertical planetary mill. Grind at 1500rpm for 10 minutes at 35℃. Then add 1.2mm zirconia beads and grind at 2200rpm for 20 minutes to obtain a composite powder with a specific surface area of ​​700m². 2 / kg; S2, nano-additives, 0.24g deionized water, disperse at 3500rpm for 5min to form a suspension; S3. Spray in 5 batches using atomized spraying and magnetic mixing; S4, vacuum dried at 50℃ for 2 hours, and 98g of repair material was obtained by passing through a 100-mesh sieve.

[0030] Mix 1.96 kg of polycyclic aromatic hydrocarbon contaminated soil with 98 g of remediation material, adjust the moisture content to 35%, till 10 cm every 2 days at 28℃, and maintain for 15 days.

[0031] Comparative Examples 1-3. Commercially available cement-based curing agent (a 1:1 mixture of ordinary silicate cement and lime) was used to remediate soil contaminated in the same batches as those in Examples 1, 2, and 3. Using a soil mass ratio of 1:8, 17.25g of curing agent was weighed to remediate 138g of petroleum hydrocarbon-contaminated soil, 10.75g of curing agent to remediate 86g of heavy metal-contaminated soil, and 24.5g of curing agent to remediate 196g of polycyclic aromatic hydrocarbon-contaminated soil. The moisture content was adjusted to 28%, and the curing temperature and cycle were consistent with the corresponding examples.

[0032] Example of results. 1. The concentration of organic pollutants (petroleum hydrocarbons and polycyclic aromatic hydrocarbons) was determined by high performance liquid chromatography, and the degradation rate of organic pollutants was calculated as (initial concentration - post-remediation concentration) / initial concentration × 100%.

[0033] 2. Determination of heavy metals (Pb) using atomic absorption spectrophotometry. 2+ Cd 2+ The leaching concentration is used to calculate the reduction rate of heavy metal leaching = (initial leaching concentration - leaching concentration after remediation) / initial leaching concentration × 100%.

[0034] The test results are shown in Table 1.

[0035] Table 1

[0036] The test results above show that the repair material provided by this invention is significantly superior to traditional curing agents in terms of organic matter degradation and heavy metal stabilization.

[0037] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A soil pollution remediation material, characterized in that, The components include the following parts by mass: Granulated blast furnace slag 40-60 parts, fly ash 15-25 parts, desulfurized gypsum 10-20 parts, activator 3-5 parts, nano-additive 1-3 parts; The activator is composed of high-alumina cement, quicklime, and anhydrous sodium silicate in a mass ratio of 1:1:1; The nano-additive is titanium dioxide / activated carbon nanocomposite particles, and the mass ratio of titanium dioxide to activated carbon is 1:9 to 1:

4.

2. The soil pollution remediation material according to claim 1, characterized in that, The titanium dioxide / activated carbon nanocomposite particles are obtained through the following steps: Mix tetrabutyl titanate and anhydrous ethanol at a volume ratio of 1:4 and stir magnetically for 10 minutes; adjust the pH to 2-3 by adding dilute nitric acid dropwise, slowly add deionized water and continue stirring until a transparent sol is formed. Dry nano-sized activated carbon was added to the sol and ultrasonically dispersed evenly. Subsequently, the mixture was stirred and evaporated into a paste under a water bath at 60°C, then transferred to a muffle furnace and calcined at 450°C for 2 hours. After cooling, it was ground through a 200-mesh sieve to obtain composite particles.

3. The soil pollution remediation material according to claim 1 or 2, characterized in that, The components include the following parts by mass: 50 parts granulated blast furnace slag, 20 parts fly ash, 18 parts desulfurized gypsum, 4 parts activator, and 2 parts nano-additives.

4. A method for preparing a soil pollution remediation material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. After mixing granulated blast furnace slag, fly ash, desulfurization gypsum, and activator, the mixture is first coarsely ground, then finely ground until the specific surface area is greater than 650 m². 2 / kg, to obtain composite powder; S2. Place the nano-additive in a high-speed disperser, add deionized water as the dispersion medium, and pre-disperse to form a uniform nano-suspension. S3. Spray the nano suspension evenly into the above composite powder in 3 to 5 batches through a dual-fluid atomizing nozzle; S4. The mixed material is vacuum dried to remove surface free moisture, and then passed through a 100-mesh sieve to obtain soil pollution remediation material.

5. The method for preparing soil pollution remediation materials according to claim 4, characterized in that, In step S1, both the coarse grinding and fine grinding are performed using a vertical planetary mill, and the temperature throughout the grinding process does not exceed 40°C.

6. The method for preparing soil pollution remediation materials according to claim 4, characterized in that, The coarse grinding in step S1 is performed at a speed of 1200~1500 rpm for 10~15 min.

7. The method for preparing soil pollution remediation materials according to claim 4, characterized in that, The grinding media used in step S1 is zirconia beads, and the rotation speed is 2000~2200 rpm.

8. The method for preparing soil pollution remediation materials according to claim 4, characterized in that, The pre-dispersion speed in step S2 is 3000~3500 rpm, and the time is 5~8 min.

9. A method for remediating soil pollution, characterized in that, The remediation method, which utilizes the soil pollution remediation materials as described in claims 1-3, includes the following steps: First, mix the soil pollution remediation material with the polluted soil at a mass ratio of 1:10~20. Then, adjust the soil moisture content to 25~35%. At room temperature, till the soil to a depth of 10~15cm every 2~3 days and continue to maintain it for 7~15 days to achieve the degradation and remediation of pollutants in the soil.

Images