Herbicide adsorption material as well as preparation method and application thereof

Abstract

The invention provides a herbicide adsorption material and a preparation method and application thereof, and the preparation method comprises the following steps: dissolving sodium alginate in water to obtain a first solution; mixing chitosan with a sodium alginate solution, then adding organic acid until the chitosan is completely dissolved, and adding an alkali solution for neutralization to obtain a second solution; adding a 1, 2, 3, 4-butanetetracarboxylic acid solution into the second solution for reaction to obtain a third solution; adding multi-walled carbon nanotubes into the third solution for reaction to obtain a fourth solution; pouring the fourth solution into a mold, and freeze-drying to obtain porous aerogel; immersing the porous aerogel into a solution containing Ca < 2 + > for reaction; and after the reaction is completed, washing and freeze-drying to obtain the herbicide adsorption material. The adsorption material prepared by the method disclosed by the invention has excellent adsorption performance, can be repeatedly used, and has a relatively great application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental governance, and more particularly to a herbicide adsorption material, a preparation method thereof, and an application thereof. Background Art

[0002] At present, herbicides play an effective role in controlling weeds in agricultural production. However, due to their excessive use, they eventually pollute nearby soil or water bodies through precipitation, surface runoff and soil leaching, leading to the deterioration of soil and water quality. Herbicide pollution has become one of the main threats to ecosystem security.

[0003] Currently, a variety of technologies are used to remove herbicides from wastewater, including biological and physicochemical treatments. Common methods include adsorption, membrane filtration, advanced oxidation processes, biodegradation, and reverse osmosis. Adsorption, as an efficient and economically viable wastewater treatment technology, demonstrates significant advantages in removing herbicides. This method leverages the surface properties of porous materials, such as activated carbon, to efficiently capture harmful substances from wastewater. The adsorption process is energy-efficient and simple to operate, making it highly suitable for wastewater treatment. In addition to activated carbon, multi-walled carbon nanotubes (MWCNTs) exhibit excellent performance in adsorption due to their high specific surface area, well-defined structure, and uniform surface properties. For example, patent CN201911125001.8 discloses a method for using carbon nanotubes to prevent crop damage from residual herbicides. By adding multi-walled carbon nanotubes to herbicide-contaminated soil, the tubes are used to prevent herbicide damage and promote crop growth. However, due to their structural characteristics, MWCNTs have limited adsorption effectiveness.

[0004] Based on this, it is urgent to develop new adsorption materials to improve the adsorption capacity of herbicides, thereby improving the management of herbicides. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a herbicide adsorption material. By modifying MWCNTs, the adsorption effect of the adsorption material on herbicides is improved, thereby improving the treatment effect on soil or sewage, providing a sustainable solution for environmental pollution control.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A method for preparing a herbicide adsorption material comprises the following steps:

[0008] S1, dissolving sodium alginate (SA) in water to obtain a first solution;

[0009] S2, mixing chitosan (CS) with sodium alginate solution, then adding organic acid until the chitosan is completely dissolved, and then adding alkaline solution to neutralize it to obtain a second solution;

[0010] S3, adding 1,2,3,4-butanetetracarboxylic acid solution (BTCA) to the second solution to react to obtain a third solution;

[0011] S4, adding multi-walled carbon nanotubes to the third solution to react to obtain a fourth solution;

[0012] S5, pouring the fourth solution into a mold, and freeze-drying to obtain a porous aerogel;

[0013] S6, immersing the porous aerogel in a Ca-containing 2+ After the reaction is completed, washing and freeze-drying are performed to obtain the herbicide adsorption material.

[0014] In some embodiments, in step S2, the mass ratio of chitosan to sodium alginate is 1-2:1-2.

[0015] In some embodiments, in step S3, the concentration of the 1,2,3,4-butanetetracarboxylic acid solution is 0.2-1.0 g / L.

[0016] In some embodiments, in step S1, the concentration of sodium alginate in the first solution is 0.1-2.0 wt %.

[0017] In some embodiments, the mass ratio of the multi-walled carbon nanotubes to the sodium alginate is 1-10:1.

[0018] In some embodiments, in step S5, the freeze-drying step is: first freezing at a temperature of -4 to -20°C for 8-24 hours, and then freezing at -50 to -100°C for 10-60 minutes.

[0019] In some embodiments, in step S6, the Ca-containing 2+ In the solution, Ca 2+ The concentration is 0.5-5wt%.

[0020] In some embodiments, the Ca-containing 2+ The solution is made by dissolving a soluble calcium salt in water.

[0021] In some embodiments, in step S2, the organic acid is acetic acid, and the concentration is 0.5-5 wt%.

[0022] In some embodiments, the alkaline solution is at least one of a sodium hydroxide solution and a potassium hydroxide solution.

[0023] The present invention also provides a herbicide adsorption material obtained by the preparation method of any of the above embodiments.

[0024] The present invention also provides the use of the above-mentioned herbicide adsorption material in removing herbicides; specifically, the use of the adsorption material in removing herbicides from soil or sewage; more specifically, the herbicides include sulfentrazone and diuron.

[0025] In some embodiments, the application method is as follows:

[0026] The adsorption material is added to a solution containing a herbicide and reacted in the dark; wherein the pH of the solution containing the herbicide is 3-7, the reaction temperature is 15-35°C, and Na + Ion concentration ≤0.05mol / L.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention modifies multi-walled carbon nanotubes with chitosan and sodium alginate, uses 1,2,3,4-butanetetracarboxylic acid as a crosslinking agent, and introduces Ca 2+ , combined with specific process conditions to react, to obtain a herbicide adsorption material; the adsorption material has a high specific surface area and a uniform porous structure, and its surface contains a rich amount of active sites that can provide a large number of active sites for pollutant adsorption; at the same time, its surface contains a rich amount of oxygen-containing functional groups, which further improves its adsorption performance for pollutants; in addition, the adsorption material has good thermal stability and is almost unaffected by the ambient temperature during use.

[0029] The adsorption material obtained by the preparation method of the present invention has a specific surface area of ​​up to 133m 2 / g or more, the adsorption capacity for sulfentrazone is more than 70mg / g, and the adsorption capacity for diuron is more than 50mg / g, which is more than 95% higher than that of multi-walled carbon nanotubes.

[0030] In addition, the adsorption material obtained by the method of the present invention can be reused and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Figures 1 and 2 are SEM images of the adsorption materials prepared in Example 1 and Comparative Example 1; Figure A is an SEM image of the adsorption material prepared in Example 1, and Figure B is an SEM image of the adsorption material prepared in Comparative Example 1;

[0032] Figure 2 The pore size distribution diagram and N2 adsorption-desorption curve of MWCNTs, SA-CS and adsorption materials; (a) is the pore size distribution diagram, and (b) is the N2 adsorption-desorption curve;

[0033] Figure 3 This is the thermogravimetric analysis curve of the adsorption material prepared in Example 1;

[0034] Figure 4 The adsorption effects of the adsorption material prepared in Example 1, the adsorption material prepared in Comparative Example 1, and the adsorption material prepared in Comparative Example 3 on sulfentrazone and diuron are shown;

[0035] Figure 5 The adsorption effects of the adsorption materials prepared with different BTCA concentrations and different SA:CS ratios in Examples 4 and 5 on sulfentrazone are shown;

[0036] Figure 6 The adsorption effect of the adsorption material in Example 1 on sulfentrazone and diuron was repeated. DETAILED DESCRIPTION

[0037] The following description sets forth numerous specific details to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific implementations disclosed below.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0039] Example 1

[0040] A method for preparing a herbicide adsorption material (SA-CS-MWCNTs) comprises the following steps:

[0041] S1. Accurately weigh 0.1 g of SA powder and dissolve it in 20 ml of deionized water. Stir for 2 h to form a uniform 0.5 wt% SA solution.

[0042] S2. Weigh the corresponding CS powder at a SA to CS mass ratio of 1.5:1 and slowly add it to the SA solution while stirring continuously for at least 2 hours to ensure uniform distribution of the CS, thereby obtaining a first mixed solution. Then, slowly add 1 wt % acetic acid solution dropwise to the first mixed solution, stir thoroughly until the CS is completely dissolved, and neutralize with 1 mol / L NaOH to obtain a uniform SA / CS solution.

[0043] S3, adding 5 ml of 0.5 g / L BTCA solution to the SA / CS solution, and performing a cross-linking reaction for 1 h to obtain a second mixed solution;

[0044] S4, adding 0.3 g of MWCNTs to the second mixed solution, ultrasonically dispersing for 30 min, and then magnetically stirring for 1 h to ensure that the MWCNTs are evenly dispersed, to obtain a SA-CS-MWCNTs solution;

[0045] S5. Pour the obtained SA-CS-MWCNTs solution into a 48-well mold, place it in a -4°C refrigerator and freeze it for 12 hours, then transfer it to a -80°C refrigerator and freeze it for 30 minutes (slow freezing at -4°C for 12 hours to regulate ice crystal growth, and rapid freezing at -80°C for 30 minutes to fix the porous structure). After freezing, vacuum drying is performed for 18 hours to obtain a porous aerogel.

[0046] S6. Prepare a 2 wt% calcium chloride (CaCl2) solution, immerse the porous aerogel in the CaCl2 solution, and stir with a magnetic stirrer at 100 rpm for 10 minutes to react; then, collect the aerogel after the reaction, wash it with deionized water 5 times, and finally freeze-dry it to obtain a composite adsorption material (SA-CS-MWCNTs).

[0047] Comparative Example 1

[0048] The preparation method of this comparative example is the same as that of Example 1, except that in step S3, 5 ml of 0.5 g / L sodium tripolyphosphate (TPP) is added to the SA / CS solution.

[0049] Comparative Example 2

[0050] A method for preparing a herbicide adsorption material (SA-CS) comprises the following steps:

[0051] S1. Accurately weigh 0.1 g of SA powder and dissolve it in 20 ml of deionized water. Stir for 2 h to form a uniform 0.5 wt% SA solution.

[0052] S2. Weigh the corresponding CS powder at a SA to CS mass ratio of 1.5:1 and slowly add it to the SA solution while stirring continuously for at least 2 hours to ensure uniform distribution of the CS, thereby obtaining a first mixed solution. Then, slowly add 1 wt % acetic acid solution dropwise to the first mixed solution, stir thoroughly until the CS is completely dissolved, and neutralize with 1 mol / L NaOH to obtain a uniform SA / CS solution.

[0053] S3. Pour the obtained SA / CS solution into a 48-well mold, place it in a -4°C refrigerator and freeze it for 12 hours, then transfer it to a -80°C refrigerator and freeze it for 30 minutes. After freezing, vacuum dry it for 18 hours to obtain a porous aerogel.

[0054] S4. Prepare a 2 wt% calcium chloride (CaCl2) solution, immerse the porous aerogel in the CaCl2 solution, and stir with a magnetic stirrer at 100 rpm for 10 min to react; then, collect the aerogel after the reaction, wash it with deionized water 5 times, and finally freeze-dry it to obtain a composite adsorbent material (SA-CS).

[0055] Comparative Example 3

[0056] The preparation method of this comparative example is the same as that of Example 1, except that BTCA is not added. That is, after obtaining the SA / CS solution in step 2, MWCNTs are directly added to react.

[0057] The adsorption material obtained in Example 1 and the adsorption material obtained in Comparative Example 1 were subjected to SEM examination, and the results were as follows: Figure 1 shown.

[0058] like Figure 1 The adsorbent material prepared in Example 1 has a richer, multi-level pore structure; in contrast, the adsorbent material prepared in Comparative Example 1 has relatively fewer and unevenly distributed pores, with larger, irregular pores visible in some areas. Furthermore, unreacted SA-CS flocculent aggregates remain on the surface of the adsorbent material prepared in Comparative Example 1.

[0059] The MWCNTs, the adsorption material prepared in Example 1 and the adsorption material prepared in Comparative Example 2 were characterized. The results are shown in Tables 1 and Figure 2 shown.

[0060] Table 1 Structural characteristics of MWCNTs, SA-CS and SA-CS-MWCNTs

[0061]

[0062]

[0063] As shown in Table 1 and Figure 2 As shown, the adsorption material prepared by the present invention has a very high total pore volume and a high average pore diameter, and has an excellent adsorption effect on pollutants.

[0064] Thermogravimetric analysis of the adsorbent material obtained in Example 1 was performed, and the analysis results were as follows: Figure 4 As shown. Figure 4 Although the adsorption material begins to decompose below 200°C, its structure can retain more than 70% below 200°C. In practical applications, it can maintain good thermal stability and is almost unaffected by ambient temperature.

[0065] Application Example 1

[0066] The adsorption characteristics of the adsorption materials prepared in Example 1, Comparative Example 1 and Comparative Example 3 as adsorbents for sulfentrazone and diuron are as follows:

[0067] Preparation of sulfentrazone solution: Dissolve sulfentrazone in water to obtain a 50 mg / L sulfentrazone solution;

[0068] Preparation of diuron solution: dissolve diuron in water to obtain a diuron solution with a concentration of 50 mg / L;

[0069] 50 mL of sulfentrazone solution or diuron solution was placed in a conical flask, and 300 mg of adsorbent material was added. All samples were placed in a constant temperature oscillator (298.15K, 160 rpm) under light-proof conditions for reaction. After quantitative sampling, the sample was filtered through a 0.22 μm microporous membrane and the residual concentration was determined by HPLC until the solution concentration remained unchanged. The adsorption performance of the adsorbent material was evaluated according to the following formula:

[0070]

[0071] Among them, Q e represents the equilibrium adsorption capacity in mg / g; C0 represents the initial mass concentration of the target pollutant in the solution before adsorption (mg / L), C e It represents the concentration of the target pollutant remaining in the solution when adsorption equilibrium is reached (mg / L), V represents the volume of the solution involved in the adsorption reaction, in liters (L), and m is the mass of the adsorbent material added, in mg.

[0072] When calculating, ensure that the units of each parameter are consistent, and all data are the average value of three parallel measurements.

[0073] The test results are shown in Table 2 and Figure 6 shown.

[0074] Table 2 Adsorption effect of the adsorption materials of Example 1, Comparative Example 1 and Comparative Example 3 on sulfentrazone and diuron

[0075] Example 1 Comparative Example 1 Comparative Example 3 sulfentrazone 70.59mg / g 55.17mg / g 45.52mg / g Diuron 53.44mg / g 46.48mg / g 42.07mg / g

[0076] Example 4 Investigating the Effect of Adsorption of Adsorbent Materials Obtained at Different BTCA Concentrations on the Adsorption of Sulfonamide

[0077] The preparation method of this embodiment is the same as that of Example 1, except that in step S3, the concentration of BTCA added is different. The obtained adsorption material is added to the sulfentrazone solution according to the above method to perform adsorption performance test. The results are as follows: Figure 5 As shown in Figure (a).

[0078] Example 5 Investigating the effect of adsorption materials obtained with different SA and CS mass ratios on the adsorption effect of sulfentrazone

[0079] The preparation method of this embodiment is the same as that of Example 1, except that in step S2, the mass ratio of SA to CS is different. The obtained adsorption material is added to the sulfentrazone solution according to the above method to perform adsorption performance test. The results are as follows: Figure 5 As shown in Figure (b).

[0080] Application Example 2

[0081] The adsorbent material after adsorbing pollutants in Example 1 was desorbed using 10 wt% dilute hydrochloric acid as an eluent and then reused. The results are as follows: Figure 6 shown.

[0082] like Figure 6 After five adsorption-desorption cycles, the adsorption capacity of the adsorbent material prepared in Example 1 for sulfentrazone and diuron decreased to 49.03 mg / g and 33.77 mg / g, respectively. Despite this decrease in adsorption performance, the material still maintained good regeneration capacity and structural stability, demonstrating its reusability in practical wastewater treatment applications and promising application prospects.

[0083] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a herbicide adsorption material, characterized in that: The following steps are involved: S1, dissolving sodium alginate in water to obtain a first solution; S2, mixing chitosan and sodium alginate solution, then adding organic acid until the chitosan is completely dissolved, and adding alkaline solution to neutralize to obtain a second solution; S3, adding 1,2,3,4-butanetetracarboxylic acid solution to the second solution to react to obtain a third solution; S4, adding multi-walled carbon nanotubes to the third solution to react to obtain a fourth solution; S5, pouring the fourth solution into a mold, and freeze-drying to obtain a porous aerogel; S6, immersing the porous aerogel in a Ca-containing 2+ After the reaction is completed, washing and freeze-drying are performed to obtain the herbicide adsorption material.

2. The method for preparing the herbicide adsorption material according to claim 1, characterized in that: In step S2, the mass ratio of chitosan to sodium alginate is 1-2:1-2.

3. The method for preparing the herbicide adsorption material according to claim 1, characterized in that: In step S3, the concentration of the 1,2,3,4-butanetetracarboxylic acid solution is 0.2-1.0 g / L.

4. The method for preparing the herbicide adsorption material according to claim 1, characterized in that: In step S1, the concentration of sodium alginate in the first solution is 0.1-2.0 wt%.

5. The method for preparing the herbicide adsorption material according to claim 1, characterized in that: The mass ratio of the multi-walled carbon nanotubes to the sodium alginate is 1-10:

1.

6. The method for preparing the herbicide adsorption material according to claim 1, characterized in that: In step S5, the freeze-drying step is: first freezing at a temperature of -4 to -20°C for 8 to 24 hours, and then freezing at -50 to -100°C for 10 to 60 minutes.

7. The method for preparing the herbicide adsorption material according to claim 1, characterized in that: In step S6, the Ca-containing 2+ In the solution, Ca 2+ The concentration is 0.5-5wt%.

8. The method for preparing the herbicide adsorption material according to claim 1, characterized in that: In step S2, the organic acid is acetic acid, and the concentration is 0.5-5 wt%.

9. The herbicide adsorption material obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the herbicide adsorption material according to claim 9 in removing herbicides.

Images