A soil remediation material for adsorbing organic pollutants, a preparation process thereof, and a soil remediation method

Abstract

The present invention relates to the technical field of soil remediation, and in particular to a soil remediation material for adsorbing organic pollutants, a preparation process thereof, and a soil remediation method. The soil remediation material for adsorbing organic pollutants is prepared by acidifying straw with sodium hypochlorite, loading ferric nitrate, then hydrothermally carbonizing, and then modifying with phenylpentyl alcohol. The soil remediation material for adsorbing organic pollutants provided by the present invention can optimize soil properties, improve the adsorption and fixation effect of soil on DBP, accelerate the ecological restoration of contaminated land, promote healthy plant growth, improve agricultural productivity, and provide a solid foundation for the sustainable development of the environment and agriculture.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular to a soil remediation material for absorbing organic pollutants, a preparation process thereof, and a soil remediation method. Background Art

[0002] In modern industrial and agricultural activities, dibutyl phthalate (DBP) is a commonly used plasticizer and is widely used in products such as plastics, rubber and coatings. However, the widespread use of DBP has also brought serious environmental problems, especially pollution in soil and water bodies. DBP has strong mobility and can easily penetrate from the soil into groundwater under the leaching effect of rainwater or irrigation, causing groundwater pollution. This pollution not only threatens the ecological environment, but may also affect human health through the food chain. Therefore, the development of effective soil remediation materials and methods to inhibit the migration of DBP in the soil has become an important topic in current environmental science research.

[0003] Traditional soil remediation methods, such as physical isolation, chemical degradation and bioremediation, can reduce soil pollution to a certain extent, but they often have problems such as low efficiency, high cost and secondary pollution when dealing with organic pollutants such as DBP. Physical isolation methods usually require a lot of engineering investment, chemical degradation methods may introduce new chemicals, and bioremediation is limited by the activity of microorganisms and environmental conditions. Therefore, finding an efficient, economical and environmentally friendly soil remediation material has become the key to solving DBP pollution. Summary of the invention

[0004] In view of this, the purpose of the present invention is to propose a soil remediation material for adsorbing organic pollutants and a soil remediation method thereof, so as to solve the problem that DBP has strong mobility in the soil and slowly penetrates into the groundwater under the leaching action of rainwater or irrigation, causing groundwater pollution.

[0005] Based on the above purpose, the present invention provides a preparation process of a soil remediation material for adsorbing organic pollutants, comprising the following steps:

[0006] (1) Add straw to deionized water, heat it to 35-45°C, then add sodium hypochlorite dropwise while stirring, stir for 20-40 minutes after the addition is complete, cool to room temperature, adjust the pH to 2-3 with aqueous hydrochloric acid, centrifuge, wash, dry, and grind through a 200-mesh sieve to obtain acidified straw;

[0007] (2) adding the acidified straw to deionized water, adjusting the pH to 11-12 with sodium hydroxide, then adding ferric nitrate, stirring for 20-40 minutes, and then hydrothermally reacting at 230-250°C for 20-30 minutes, centrifuging, washing, and drying to obtain modified biochar;

[0008] (3) Add the modified biochar to N,N-dimethylformamide, ultrasonicate for 5-20 min, then add 4-dimethylaminopyridine and phenylpentanol in sequence, raise the temperature to 55-65°C, stir and react for 2.5-3.5 h, centrifuge, wash, and dry to obtain a soil remediation material that adsorbs organic pollutants.

[0009] Preferably, the straw in step (1) is one of corn straw, rice straw, wheat straw or sugarcane straw.

[0010] Preferably, in step (1), the straw is crushed through a 50-100 mesh sieve before being added.

[0011] Preferably, the concentration of the aqueous hydrochloric acid solution in step (1) is 1-5 mol / L.

[0012] Preferably, in step (1), the weight ratio of straw, deionized water and sodium hypochlorite is 10:50-200:1-3.

[0013] Preferably, in step (2), the weight ratio of acidified straw, deionized water and ferric nitrate is 5:30-100:0.1-1.

[0014] Preferably, in step (3), the weight ratio of modified biochar, N,N-dimethylformamide, 4-dimethylaminopyridine and phenylpentanol is 5:20-50:0.01-0.1:0.3-0.8.

[0015] Furthermore, the present invention also provides a soil remediation material for adsorbing organic pollutants, which is obtained by a preparation process of the soil remediation material for adsorbing organic pollutants.

[0016] Furthermore, the present invention also provides a soil remediation method, which comprises adding soil remediation materials that adsorb organic pollutants into contaminated soil.

[0017] Preferably, the added amount is 0.5-2% of the weight of the contaminated soil.

[0018] Beneficial effects of the present invention:

[0019] The soil remediation material for adsorbing organic pollutants provided by the present invention effectively inhibits the migration of organic pollutant plasticizer DBP in the soil, achieving the effect of immobilization. This is mainly due to the acidified straw, the iron oxide generated in situ by ferric nitrate, and the pore modification of phenylpentanol with a suitable carbon chain length. The acidified straw effectively enhances the fixation effect of DBP, and the ferric nitrate provides strong adsorption through its in situ derived iron oxide network, significantly improving the cation exchange capacity of the soil. The phenylpentanol effectively adsorbs and restricts DBP through π-π interaction and optimization of the pore structure, preventing its desorption and escape.

[0020] The soil remediation material for adsorbing organic pollutants provided by the present invention can be directly applied to land contaminated by the organic pollutant plasticizer DBP, which can not only effectively prevent the migration of organic pollutants in the soil, but also significantly improve the pH value, cation exchange capacity and organic carbon content of the soil. The optimized soil environment can accelerate the ecological recovery of contaminated land, promote the healthy growth of plants, and improve agricultural productivity, providing a solid foundation for the sustainable development of the environment and agriculture. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0022] Embodiment 1:

[0023] (1) Add 10 g of rice straw crushed through a 50-mesh sieve to 50 g of deionized water, heat to 35°C, then dropwise add 1 g of sodium hypochlorite while stirring. After the addition is complete, stir for 20 min, cool to room temperature, adjust the pH to 2.9 with a 0.5 mol / L hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 200-mesh sieve to obtain acidified rice straw;

[0024] (2) Add 5 g of acidified rice straw to 30 g of deionized water, adjust the pH to 11.4 with sodium hydroxide, then add 0.1 g of ferric nitrate, stir for 20 min, then transfer to a hydrothermal reactor, perform hydrothermal reaction at 230 °C for 30 h, centrifuge, wash with water, and dry to obtain modified biochar;

[0025] (3) Add 5 g of modified biochar to 20 g of N,N-dimethylformamide, ultrasonicate for 5 min, then add 0.01 g of 4-dimethylaminopyridine and 0.3 g of phenylpentanol in sequence, heat to 55 °C, stir to react for 2.5 h, centrifuge, wash, and dry to obtain a soil remediation material that adsorbs organic pollutants.

[0026] Embodiment 2:

[0027] (1) Add 10 g of corn stalks crushed through a 100-mesh sieve into 100 g of deionized water, heat to 40°C, then dropwise add 1.5 g of sodium hypochlorite while stirring. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 2.5 with a 1 mol / L hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 200-mesh sieve to obtain acidified corn stalks;

[0028] (2) Add 5 g of acidified corn straw to 50 g of deionized water, adjust the pH to 11.2 with sodium hydroxide, then add 0.5 g of ferric nitrate, stir for 30 min, then transfer to a hydrothermal reactor, perform hydrothermal reaction at 240 °C for 24 h, centrifuge, wash with water, and dry to obtain modified biochar;

[0029] (3) Add 5 g of modified biochar to 30 g of N,N-dimethylformamide, ultrasonicate for 10 min, then add 0.05 g of 4-dimethylaminopyridine and 0.5 g of phenylpentanol in sequence, heat to 60 °C, stir to react for 3 h, centrifuge, wash, and dry to obtain a soil remediation material that adsorbs organic pollutants.

[0030] Embodiment 3:

[0031] (1) Add 10 g of wheat straw crushed through a 100-mesh sieve into 200 g of deionized water, heat to 45°C, then dropwise add 3 g of sodium hypochlorite while stirring. After the addition is complete, stir for 40 min, cool to room temperature, adjust the pH to 2.1 with a 5 mol / L hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 200-mesh sieve to obtain acidified wheat straw;

[0032] (2) Add 5 g of acidified wheat straw to 100 g of deionized water, adjust the pH to 11.8 with sodium hydroxide, then add 1 g of ferric nitrate, stir for 40 min, then transfer to a hydrothermal reactor, perform hydrothermal reaction at 250 °C for 20 h, centrifuge, wash with water, and dry to obtain modified biochar;

[0033] (3) Add 50 g of N,N-dimethylformamide to 5 g of modified biochar, ultrasonicate for 20 min, then add 0.1 g of 4-dimethylaminopyridine and 0.8 g of phenylpentanol in sequence, heat to 65 °C, stir to react for 3.5 h, centrifuge, wash, and dry to obtain a soil remediation material that adsorbs organic pollutants.

[0034] Comparative Example 1:

[0035] The difference between Comparative Example 1 and Example 2 is that the corn stalks are not acidified;

[0036] The specific steps are as follows:

[0037] (1) Add 5 g of corn stalks crushed through a 200-mesh sieve into 50 g of deionized water, adjust the pH to 11.2 with sodium hydroxide, then add 0.5 g of ferric nitrate, stir for 30 min, then transfer to a hydrothermal reactor, perform hydrothermal reaction at 240 °C for 24 h, centrifuge, wash with water, and dry to obtain modified biochar;

[0038] (2) Add 5 g of modified biochar to 30 g of N,N-dimethylformamide, ultrasonicate for 10 min, then add 0.05 g of 4-dimethylaminopyridine and 0.5 g of phenylpentanol in sequence, heat to 60 °C, stir to react for 3 h, centrifuge, wash, and dry to obtain soil remediation material.

[0039] Comparative Example 2:

[0040] The difference between Comparative Example 2 and Example 2 is that no ferric nitrate is added;

[0041] The specific steps are as follows:

[0042] (1) Add 10 g of corn stalks crushed through a 100-mesh sieve into 100 g of deionized water, heat to 40°C, then dropwise add 1.5 g of sodium hypochlorite while stirring. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 2.4 with a 1 mol / L hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 200-mesh sieve to obtain acidified corn stalks;

[0043] (2) Add 5 g of acidified corn stalks to 50 g of deionized water, adjust the pH to 11.2 with sodium hydroxide, then transfer to a hydrothermal reactor, perform hydrothermal reaction at 240 °C for 24 h, centrifuge, wash with water, and dry to obtain modified biochar;

[0044] (3) Add 5 g of modified biochar to 30 g of N,N-dimethylformamide, ultrasonicate for 10 min, then add 0.05 g of 4-dimethylaminopyridine and 0.5 g of phenylpentanol in sequence, heat to 60 °C, stir to react for 3 h, centrifuge, wash, and dry to obtain a soil remediation material.

[0045] Comparative Example 3:

[0046] The difference between Comparative Example 3 and Example 2 is that: no phenylpentyl alcohol modification is used;

[0047] The specific steps are as follows:

[0048] (1) Add 10 g of corn stalks crushed through a 100-mesh sieve into 100 g of deionized water, heat to 40°C, then dropwise add 1.5 g of sodium hypochlorite while stirring. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 2.5 with a 1 mol / L hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 200-mesh sieve to obtain acidified corn stalks;

[0049] (2) Add 5 g of acidified corn straw to 50 g of deionized water, adjust the pH to 11.2 with sodium hydroxide, then add 0.5 g of ferric nitrate, stir for 30 min, and then transfer to a hydrothermal reactor for hydrothermal reaction at 240 °C for 24 h. Centrifuge, wash with water, and dry to obtain a soil remediation material.

[0050] Comparative Example 4:

[0051] The difference between Comparative Example 4 and Example 2 is that phenylpentanol is replaced by benzyl alcohol;

[0052] (1) Add 10 g of corn stalks crushed through a 100-mesh sieve into 100 g of deionized water, heat to 40°C, then dropwise add 1.5 g of sodium hypochlorite while stirring. After the addition is complete, stir for 30 min, cool to room temperature, adjust the pH to 2.5 with a 1 mol / L hydrochloric acid aqueous solution, centrifuge, wash, dry, and grind through a 200-mesh sieve to obtain acidified corn stalks;

[0053] (2) Add 5 g of acidified corn straw to 50 g of deionized water, adjust the pH to 11.2 with sodium hydroxide, then add 0.5 g of ferric nitrate, stir for 30 min, then transfer to a hydrothermal reactor, perform hydrothermal reaction at 240 °C for 24 h, centrifuge, wash with water, and dry to obtain modified biochar;

[0054] (3) Add 5 g of modified biochar to 30 g of N,N-dimethylformamide, ultrasonicate for 10 min, then add 0.05 g of 4-dimethylaminopyridine and 0.5 g of benzyl alcohol in sequence, heat to 60 °C, stir to react for 3 h, centrifuge, wash, and dry to obtain a soil remediation material that adsorbs organic pollutants.

[0055] The specific steps are as follows:

[0056] Performance Test:

[0057] Test soil: Artificially prepare contaminated soil, the preparation method is as follows: first prepare the DBP solution, then spray the DBP solution evenly on the blank soil, mix it thoroughly, add blank soil after air drying, so that the concentration of DBP in the soil is 100 mg / kg, and incubate it at constant temperature at room temperature for 15 days for use.

[0058] Leaching experiment: A 30 cm long, 5 cm inner diameter organic glass column was selected. First, 2 cm thick clean quartz sand was added to the bottom of the glass column. The test soil mixed with 1 wt% of the soil remediation material prepared in the embodiment and the comparative example and the test soil without adding the soil remediation material were added as the control group. The filling height was 20 cm. The soil column was gently vibrated to make it dense. 2 cm thick quartz sand was added to the top of the soil column. Finally, the leaching column was wrapped with tin foil for light protection and placed in a constant temperature environment of 25 ° C. Water was added from the top to 70% of the field water holding capacity of the soil. After 24 hours of equilibrium, deionized water was added from the top by intermittent leaching. 150 mL of deionized water was added every week, and the leaching solution was collected. The leaching process was 7 weeks. After the leaching was completed, the soil was taken out, air-dried and sieved, and various indicators of the soil were measured. The results are shown in Table 1.

[0059] Extraction and determination conditions of DBP in the leaching solution: After filtering through a 0.45 μm water system microporous filter membrane, the DBP content in the leaching solution was determined by ultra-high performance liquid chromatography, and the leaching loss was calculated. The results are shown in Table 1.

[0060] Extraction and determination conditions of DBP in soil: Weigh 1 g of soil sample after leaching experiment, extract with 10 mL petroleum ether by ultrasonic, and then determine the DBP content extracted in the soil by gas chromatography. The results are shown in Table 1.

[0061] Table 1 Performance test results

[0062]

[0063] Data Analysis:

[0064] From the data of Examples 1-3, the control group and the blank soil in Table 1, it can be seen that the soil remediation material for adsorbing organic pollutants prepared by the present invention can effectively improve the soil pH, cation exchange capacity and organic carbon content. These characteristics make it an ideal choice in the process of soil remediation and improvement, which helps to accelerate the ecological recovery of contaminated land, thereby promoting the healthy growth of plants and the improvement of agricultural productivity. In addition, from the data of the leaching experiment, it can be seen that the soil remediation material for adsorbing organic pollutants prepared by the present invention can effectively inhibit the migration of organic pollutants-plasticizer DBP in the soil, and after the leaching experiment, the content of plasticizer DBP extracted from the soil is only 1.9%-2.5% of the initial concentration. This is mainly because the soil containing the soil remediation material for adsorbing organic pollutants has a strong fixation effect on the plasticizer DBP, making it difficult to be leached out by the extractant.

[0065] It can be seen from the data of Example 2 and Comparative Example 1 in Table 1 that the acidification of corn stalks helps to optimize the physical and chemical properties of the soil and can significantly improve the fixation effect of the soil on the plasticizer DBP.

[0066] It can be seen from the data of Example 2 and Comparative Example 2 in Table 1 that the addition of ferric nitrate helps to increase the pH and cation exchange capacity of the soil, and can further improve the soil's fixation effect on the plasticizer DBP. This is mainly because the in-situ generated iron oxide has a strong adsorption capacity and can effectively adsorb and fix organic pollutants.

[0067] It can be seen from the data of Example 2 and Comparative Examples 3-4 in Table 1 that phenylpentyl alcohol with a suitable carbon chain length helps to improve the adsorption and fixation of the plasticizer DBP by the soil. This is mainly because phenylpentyl alcohol is grafted into the pores of the modified biochar. On the one hand, it adsorbs the plasticizer DBP through π-π interaction, and on the other hand, it limits the desorption and escape of the plasticizer DBP through suitable pore modification.

[0068] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A preparation process of a soil remediation material for adsorbing organic pollutants, characterized in that: The following steps are involved: (1) Add straw to deionized water, heat it to 35-45°C, then add sodium hypochlorite dropwise while stirring, stir for 20-40 minutes after the addition is complete, cool to room temperature, adjust the pH to 2-3 with aqueous hydrochloric acid, centrifuge, wash, dry, and grind through a 200-mesh sieve to obtain acidified straw; (2) adding the acidified straw to deionized water, adjusting the pH to 11-12 with sodium hydroxide, then adding ferric nitrate, stirring for 20-40 minutes, and then hydrothermally reacting at 230-250°C for 20-30 minutes, centrifuging, washing, and drying to obtain modified biochar; (3) Add the modified biochar to N,N-dimethylformamide, ultrasonicate for 5-20 min, then add 4-dimethylaminopyridine and phenylpentanol in sequence, raise the temperature to 55-65°C, stir and react for 2.5-3.5 h, centrifuge, wash, and dry to obtain a soil remediation material that adsorbs organic pollutants.

2. The preparation process of the soil remediation material for adsorbing organic pollutants according to claim 1, characterized in that: The straw in step (1) is one of corn straw, rice straw, wheat straw or sugarcane straw.

3. The preparation process of the soil remediation material for adsorbing organic pollutants according to claim 1, characterized in that: In the step (1), the straw is crushed and passed through a 50-100 mesh sieve before being added.

4. The preparation process of the soil remediation material for adsorbing organic pollutants according to claim 1, characterized in that: The concentration of the hydrochloric acid aqueous solution in step (1) is 1-5 mol / L.

5. The preparation process of the soil remediation material for adsorbing organic pollutants according to claim 1, characterized in that: In the step (1), the weight ratio of straw, deionized water and sodium hypochlorite is 10:50-200:1-3.

6. The preparation process of the soil remediation material for adsorbing organic pollutants according to claim 1, characterized in that: In the step (2), the weight ratio of acidified straw, deionized water and ferric nitrate is 5:30-100:0.1-1.

7. The preparation process of the soil remediation material for adsorbing organic pollutants according to claim 1, characterized in that: In the step (3), the weight ratio of the modified biochar, N,N-dimethylformamide, 4-dimethylaminopyridine and phenylpentanol is 5:20-50:0.01-0.1:0.3-0.

8.

8. A soil remediation material for adsorbing organic pollutants, characterized in that: The soil remediation material for adsorbing organic pollutants is obtained by the preparation process of any one of claims 1 to 7.

9. A soil remediation method, characterized in that: The soil remediation material for adsorbing organic pollutants as claimed in claim 8 can be added to the contaminated soil, and the added amount is 0.5-2% of the weight of the contaminated soil.

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