Sewage treatment agent and preparation method thereof

Abstract

The invention discloses a sewage treatment agent and a preparation method thereof, and relates to the field of water treatment materials. When the sewage treatment agent is prepared, chitosan sequentially reacts with diethyl allyl phosphate, maleic anhydride and N-(2-sulfydryl)-guanidine, and functional chitosan is prepared; the preparation method comprises the following steps: sequentially reacting silicon dioxide with 3-bromopropyltrimethoxysilane, anthraquinone and 1, 4-bis (bromomethyl) benzene to prepare modified silicon dioxide; and reacting the modified silicon dioxide with the functional chitosan, mixing with ferric acetate, and crushing to obtain the sewage treatment agent. The sewage treatment agent prepared by the invention has the functions of resisting bacteria, adsorbing and degrading organic pollutants and adsorbing metal ions.

Description

Technical Field

[0001] The invention relates to the field of water treatment materials, in particular to a sewage treatment agent and a preparation method thereof. Background Art

[0002] With the rapid development of industrialization and urbanization, the problem of surface water pollution has become increasingly prominent and has become an important issue that needs to be urgently addressed in the current environmental protection field. Surface water pollution mainly comes from various sources such as industrial wastewater, agricultural emissions and domestic sewage. These pollutants enter surface water bodies through different pathways, which not only have a negative impact on species living in the water, but also have a negative impact on a wider range of natural organisms. Therefore, sewage treatment agents have received widespread attention.

[0003] As for water pollution, the most prominent pollutants are heavy metals and organic pollutants. Heavy metals are produced and released into the environment through various industrial production processes and other human activities. Due to their persistence and toxicity, their presence will have an impact on the health of biological organisms and the environment. There are many types of organic wastes, which generally have complex and stable chemical structures. They are difficult to degrade and easily accumulate in large quantities, which will also have an impact on the health of biological organisms and the environment. Therefore, this application introduces a sewage treatment agent with the ability to adsorb heavy metal ions and adsorb and degrade organic pollutants and a preparation method thereof. Summary of the invention

[0004] The purpose of the present invention is to provide a sewage treatment agent and a preparation method thereof to solve the problems existing in the prior art.

[0005] A sewage treatment agent, which is prepared by reacting modified silicon dioxide and functionalized chitosan, mixing with ferric acetate, and crushing;

[0006] The functionalized chitosan is prepared by sequentially reacting chitosan with diethyl allyl phosphate, maleic anhydride and N-(2-mercapto)-guanidine;

[0007] The modified silicon dioxide is prepared by reacting silicon dioxide with 3-bromopropyltrimethoxysilane, anthraquinone and 1,4-di(bromomethyl)benzene in sequence.

[0008] A method for preparing a sewage treatment agent, the method for preparing the sewage treatment agent mainly comprises the following preparation steps:

[0009] (1) Mix N,N-dimethylformamide, maleic anhydride, and sodium acetate in a molar ratio of 8 - 10:1:1, stir at 200 - 300 r / min for 10 - 20 min, add pre-modified chitosan which is 9 - 11 times the mass of maleic anhydride, heat up to 85 - 95 °C, and under nitrogen protection, continue to stir for 5.5 - 6.5 h. Then dry under vacuum at -10 - 0 °C for 22 - 26 h, wash with deionized water 3 - 5 times, and dry under vacuum at -10 - 0 °C for 22 - 26 h again to obtain modified chitosan;

[0010] (2) Mix pre-modified silica, anthraquinone, 1,2-dichloroethane, ferric chloride, and 1,4-bis(bromomethyl)benzene in a mass ratio of 8 - 10:1:65 - 75:0.5 - 0.7:5.5 - 5.8, stir at 75 - 85 °C, 200 - 300 r / min under nitrogen protection for 22 - 26 h, cool to room temperature, filter, wash with deionized water 5 - 7 times, and dry under vacuum at 55 - 65 °C for 11 - 13 h to obtain modified silica;

[0011] (3) Mix modified silica, functionalized chitosan, and N,N-dimethylformamide in a mass ratio of 1:1:8 - 12, heat up to 55 - 65 °C, stir at 200 - 300 r / min for 12 - 13 h, add a 20% iron acetate ethanol solution which is 0.2 - 0.3 times the mass of modified silica, continue to stir for 15 - 25 min, cool to room temperature, dry under vacuum at 55 - 65 °C for 22 - 26 h, crush, and pass through a 5-mesh sieve to obtain the sewage treatment agent.

[0012] As an optimization, the pre-modified chitosan in step (1) is prepared by mixing diethyl allyl phosphate, chitosan, and ethanol in a mass ratio of 1:2 - 3:16 - 20, stirring at 200 - 300 r / min, 45 - 55 °C under argon protection for 38 - 42 h, filtering, washing with ethanol 3 - 5 times, and drying under vacuum at -10 - 0 °C for 11 - 13 h.

[0013] As an optimization, the chitosan is chitosan with a molecular weight of 2000.

[0014] As an optimization, the pre-modified silica in step (2) is prepared by mixing silica, 3-bromopropyltrimethoxysilane, and isopropanol in a mass ratio of 1:0.14 - 0.16:10 - 12, adjusting the pH to 3.8 - 4.2 with 0.1 mol / L acetic acid solution, stirring at 85 - 95 °C, 200 - 300 r / min for 5 - 7 h, filtering, washing with deionized water 3 - 5 times, and drying at 90 - 100 °C for 2 - 4 h.

[0015] As an optimization, the silica is 200-mesh silica.

[0016] As an optimization, the functionalized chitosan described in step (3) is prepared by mixing modified chitosan, deionized water, and azobisisobutyronitrile in a mass ratio of 1:18 - 22:0.05 - 0.07, stirring at 200 - 300 r / min for 2 - 3 min, uniformly adding an N-(2-mercapto)-guanidine solution with the same mass as the modified chitosan within 5 - 7 min, stirring at 65 - 75 °C for 170 - 190 min, adding a 2,6-di-tert-butyl-4-methylphenol solution with a mass 0.2 - 0.3 times that of the modified chitosan, cooling to room temperature, filtering, washing with ethanol 3 - 5 times, and vacuum drying at -10 - 0 °C for 22 - 26 h.

[0017] As an optimization, the N-(2-mercapto)-guanidine solution is prepared by uniformly mixing N-(2-mercapto)-guanidine and deionized water in a mass ratio of 1:8 - 10.

[0018] As an optimization, the 2,6-di-tert-butyl-4-methylphenol solution is prepared by uniformly mixing 2,6-di-tert-butyl-4-methylphenol and ethanol in a mass ratio of 1:8 - 12.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0020] When preparing the sewage treatment agent of the present invention, chitosan is successively reacted with diethyl allylphosphate, maleic anhydride, and N-(2-mercapto)-guanidine to obtain functionalized chitosan; silica is successively reacted with 3-bromopropyltrimethoxysilane, anthraquinone, and 1,4-bis(bromomethyl)benzene to obtain modified silica; the modified silica and the functionalized chitosan are reacted and then mixed with iron acetate and pulverized to obtain the sewage treatment agent.

[0021] First, chitosan is successively reacted with diethyl allylphosphate, maleic anhydride, and N-(2-mercapto)-guanidine to obtain functionalized chitosan; introducing phosphate ester on the surface of chitosan can be hydrolyzed under acidic conditions to form phosphate anions, adsorbing cationic pollutants in the water body, thereby accelerating the degradation efficiency of pollutants; the reaction with maleic anhydride introduces carboxyl groups on the surface of chitosan, and the carboxyl functional group has strong electrophilic properties and can coordinate with metal ions to achieve the effect of adsorbing metal ions in sewage. By reacting with N-(2-mercapto)-guanidine, guanidine is introduced. Guanidine can specifically interact with the ribosomal RNA part of bacteria, blocking the normal chain reaction required for protein synthesis; it can also interact with the circular structure of bacterial DNA, inhibiting the replication and reproduction of bacteria, thereby improving the antibacterial effect of the material.

[0022] Secondly, silica is successively reacted with 3-bromopropyltrimethoxysilane and anthraquinone with 1,4-bis(bromomethyl)benzene to prepare modified silica; an anthraquinone structure is introduced on the surface of silica, which can complex with iron ions. Iron ions can degrade organic substances under photocatalytic conditions. And due to carrying a positive charge, when it contacts the cell membrane of microorganisms, it will have electrostatic attraction with the negatively charged cell membrane, penetrate the cell membrane and enter the bacteria, and react with sulfhydryl groups, amino groups, etc. on the proteins in the bacteria, destroying the active center of the protein, thereby causing cell death or loss of the ability to divide and proliferate, thus improving the antibacterial effect of the material; and the anthraquinone structure can complex with metal ions and adsorb metal ions in sewage.

[0023] Finally, the modified silica and functionalized chitosan are reacted, and then mixed with iron acetate and pulverized to prepare a sewage treatment agent. The bromo group on the surface of the modified silica reacts with the tertiary amine on the surface of the functionalized chitosan to form a quaternary ammonium. The quaternary ammonium salt, as a cation, can well adsorb anionic pollutants in water, thereby accelerating the degradation efficiency of pollutants. And the quaternary ammonium salt can be adsorbed on the surface of bacteria, insert the hydrophobic group into the lipid layer, change the permeability of the cell membrane, destroy the membrane structure, cause the leakage of intracellular substances, affect the normal functions and metabolism of cells, and can also denature proteins, resulting in cell death, thereby improving the antibacterial effect of the material. Specific embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Example 1:

[0026] A preparation method of a sewage treatment agent mainly includes the following preparation steps:

[0027] (1) Mix diethyl allylphosphate, chitosan with a molecular weight of 2000, and ethanol in a mass ratio of 1:2:16. Stir at 200 r / min, 45 °C under argon protection for 38 h, filter, wash with ethanol 3 times, and vacuum dry at -10 °C for 11 h to obtain pre-modified chitosan; Mix N,N-dimethylformamide, maleic anhydride, and sodium acetate in a molar ratio of 8:1:1, stir at 200 r / min for 10 min, add pre-modified chitosan 9 times the mass of maleic anhydride, heat to 85 °C, and continue to stir for 5.5 h under nitrogen protection. Vacuum dry at -10 °C for 22 h, wash with deionized water 3 times, and then vacuum dry at -10 °C for 22 h to obtain modified chitosan; Mix N-(2-mercapto)-guanidine and deionized water in a mass ratio of 1:8 and mix evenly to obtain an N-(2-mercapto)-guanidine solution; Mix 2,6-di-tert-butyl-4-methylphenol and ethanol in a mass ratio of 1:8 and mix evenly to obtain a 2,6-di-tert-butyl-4-methylphenol solution; Mix modified chitosan, deionized water, and azobisisobutyronitrile in a mass ratio of 1:18:0.05, stir at 200 r / min for 2 min, and uniformly add an N-(2-mercapto)-guanidine solution equal to the mass of modified chitosan within 5 min. Stir at 65 °C for 170 min, add a 2,6-di-tert-butyl-4-methylphenol solution 0.2 times the mass of modified chitosan, cool to room temperature, filter, wash with ethanol 3 times, and vacuum dry at -10 °C for 22 h to obtain functionalized chitosan;

[0028] (2) Mix 200-mesh silica, 3-bromopropyltrimethoxysilane, and isopropanol in a mass ratio of 1:0.14:10, adjust the pH to 3.8 with 0.1 mol / L acetic acid solution, stir at 85 °C, 200 r / min for 5 h, filter, wash with deionized water 3 times, and dry at 90 °C for 2 h to obtain pre-modified silica; Mix pre-modified silica, anthraquinone, 1,2-dichloroethane, ferric chloride, and 1,4-bis(bromomethyl)benzene in a mass ratio of 8:1:65:0.5:5.5, stir at 75 °C, 200 r / min under nitrogen protection for 22 h, cool to room temperature, filter, wash with deionized water 5 times, and vacuum dry at 55 °C for 11 h to obtain modified silica;

[0029] (3) Mix modified silica, functionalized chitosan, and N,N-dimethylformamide in a mass ratio of 1:1:8, heat to 55 °C, stir at 200 r / min for 12 h, add a 20% iron acetate ethanol solution 0.2 times the mass of modified silica, continue to stir for 15 min, cool to room temperature, vacuum dry at 55 °C for 22 h, crush, and pass through a 5-mesh sieve to obtain a sewage treatment agent.

[0030] Example 2:

[0031] A preparation method of a sewage treatment agent mainly includes the following preparation steps:

[0032] (1) Mix diethyl allyl phosphate, chitosan with a molecular weight of 2000, and ethanol in a mass ratio of 1:2.5:18. Stir at 250 r / min, 50 °C under argon protection for 40 h, filter, wash 4 times with ethanol, and vacuum dry at -5 °C for 12 h to obtain pre-modified chitosan; Mix N,N-dimethylformamide, maleic anhydride, and sodium acetate in a molar ratio of 9:1:1, stir at 250 r / min for 15 min, add pre-modified chitosan 10 times the mass of maleic anhydride, raise the temperature to 90 °C, and continue to stir for 6 h under nitrogen protection. Vacuum dry at -5 °C for 24 h, wash 4 times with deionized water, and then vacuum dry at -5 °C for 24 h to obtain modified chitosan; Mix N-(2-mercapto)-guanidine and deionized water in a mass ratio of 1:9 and mix evenly to obtain an N-(2-mercapto)-guanidine solution; Mix 2,6-di-tert-butyl-4-methylphenol and ethanol in a mass ratio of 1:10 and mix evenly to obtain a 2,6-di-tert-butyl-4-methylphenol solution; Mix modified chitosan, deionized water, and azobisisobutyronitrile in a mass ratio of 1:20:0.06, stir at 250 r / min for 2.5 min, and uniformly add an N-(2-mercapto)-guanidine solution with the same mass as modified chitosan within 6 min. Stir at 70 °C for 180 min, add a 2,6-di-tert-butyl-4-methylphenol solution 0.25 times the mass of modified chitosan, cool to room temperature, filter, wash 4 times with ethanol, and vacuum dry at -5 °C for 24 h to obtain functionalized chitosan;

[0033] (2) Mix 200-mesh silica, 3-bromopropyltrimethoxysilane, and isopropanol in a mass ratio of 1:0.15:11, adjust the pH to 4 with a 0.1 mol / L acetic acid solution, stir at 90 °C, 250 r / min for 6 h, filter, wash 4 times with deionized water, and dry at 95 °C for 3 h to obtain pre-modified silica; Mix pre-modified silica, anthraquinone, 1,2-dichloroethane, ferric chloride, and 1,4-bis(bromomethyl)benzene in a mass ratio of 9:1:70:0.6:5.7, stir at 80 °C, 250 r / min under nitrogen protection for 24 h, cool to room temperature, filter, wash 6 times with deionized water, and vacuum dry at 60 °C for 12 h to obtain modified silica;

[0034] (3) Mix modified silica, functionalized chitosan, and N,N-dimethylformamide in a mass ratio of 1:1:10, raise the temperature to 60 °C, stir at 250 r / min for 12.5 h, add a 20% iron acetate ethanol solution 0.25 times the mass of modified silica, continue to stir for 20 min, cool to room temperature, vacuum dry at 60 °C for 24 h, pulverize, and pass through a 5-mesh sieve to obtain the sewage treatment agent.

[0035] Example 3:

[0036] A preparation method of a sewage treatment agent mainly includes the following preparation steps:

[0037] (1) Mix diethyl allyl phosphate, chitosan with a molecular weight of 2000, and ethanol in a mass ratio of 1:3:20. Stir at 300 r / min, 55 °C under argon protection for 42 h, filter, wash with ethanol 5 times, and vacuum dry at 0 °C for 13 h to obtain pre-modified chitosan; Mix N,N-dimethylformamide, maleic anhydride, and sodium acetate in a molar ratio of 10:1:1, stir at 300 r / min for 20 min, add pre-modified chitosan 11 times the mass of maleic anhydride, heat up to 95 °C, and continue to stir for 6.5 h under nitrogen protection. Vacuum dry at 0 °C for 26 h, wash with deionized water 5 times, and then vacuum dry at 0 °C for 26 h to obtain modified chitosan; Mix N-(2-mercapto)-guanidine and deionized water in a mass ratio of 1:10 and mix evenly to obtain an N-(2-mercapto)-guanidine solution; Mix 2,6-di-tert-butyl-4-methylphenol and ethanol in a mass ratio of 1:12 and mix evenly to obtain a 2,6-di-tert-butyl-4-methylphenol solution; Mix modified chitosan, deionized water, and azobisisobutyronitrile in a mass ratio of 1:22:0.07, stir at 300 r / min for 3 min, and uniformly add an N-(2-mercapto)-guanidine solution with the same mass as the modified chitosan within 7 min. Stir at 75 °C for 190 min, add a 2,6-di-tert-butyl-4-methylphenol solution 0.3 times the mass of the modified chitosan, cool to room temperature, filter, wash with ethanol 5 times, and vacuum dry at 0 °C for 26 h to obtain functionalized chitosan;

[0038] (2) Mix 200-mesh silica, 3-bromopropyltrimethoxysilane, and isopropanol in a mass ratio of 1:0.16:12, adjust the pH to 4.2 with 0.1 mol / L acetic acid solution, stir at 95 °C, 300 r / min for 7 h, filter, wash with deionized water 5 times, and dry at 100 °C for 4 h to obtain pre-modified silica; Mix pre-modified silica, anthraquinone, 1,2-dichloroethane, ferric chloride, and 1,4-bis(bromomethyl)benzene in a mass ratio of 10:1:75:0.7:5.8, stir at 85 °C, 300 r / min under nitrogen protection for 26 h, cool to room temperature, filter, wash with deionized water 7 times, and vacuum dry at 65 °C for 13 h to obtain modified silica;

[0039] (3) Mix modified silica, functionalized chitosan, and N,N-dimethylformamide in a mass ratio of 1:1:12, heat up to 65°C, stir at 300 r / min for 13 h, add an iron acetate ethanol solution with a mass fraction of 20% and 0.3 times the mass of the modified silica, continue stirring for 25 min, cool to room temperature, vacuum dry at 65°C for 26 h, pulverize, and pass through a 5-mesh sieve to obtain a sewage treatment agent.

[0040] Comparative Example 1:

[0041] The preparation method of the sewage treatment agent in Comparative Example 1 is different from that in Example 2 in step (1). Modify step (1) as follows: Mix diethyl allyl phosphate, chitosan with a molecular weight of 2000, and ethanol in a mass ratio of 1:2.5:18, stir at 250 r / min, 50°C under argon protection for 40 h, filter, wash with ethanol 4 times, vacuum dry at -5°C for 12 h to obtain pre-modified chitosan; Mix N,N-dimethylformamide, maleic anhydride, and sodium acetate in a molar ratio of 9:1:1, stir at 250 r / min for 15 min, add pre-modified chitosan 10 times the mass of maleic anhydride, heat up to 90°C, continue stirring for 6 h under nitrogen protection, vacuum dry at -5°C for 24 h, wash with deionized water 4 times, and then vacuum dry at -5°C for 24 h to obtain functionalized chitosan. The remaining steps are the same as in Example 2.

[0042] Comparative Example 2:

[0043] The preparation method of the sewage treatment agent in Comparative Example 2 is only different from that in Example 2 in that chitosan is not modified. The remaining steps are the same as in Example 2.

[0044] Comparative Example 3:

[0045] The preparation method of the sewage treatment agent in Comparative Example 3 is different from that in Example 2 in that silica is not modified and step (3) is different. Modify step (3) as follows: Mix 200-mesh silica, functionalized chitosan, and N,N-dimethylformamide in a mass ratio of 1:1:10, stir at 250 r / min for 20 min, cool to room temperature, vacuum dry at 60°C for 24 h, pulverize, and pass through a 5-mesh sieve to obtain a sewage treatment agent. The remaining steps are the same as in Example 2.

[0046] Test Example 1:

[0047] Antibacterial test:

[0048] Test method: Conduct the test according to GB / T31402-2015, and the selected bacterial strains are Staphylococcus aureus and Escherichia coli respectively. The results are shown in Table 1.

[0049] Table 1

[0050]

[0051] It can be found from the comparison of the experimental data in Table 1 that the sewage treatment agent prepared by the present invention has good antibacterial ability.

[0052] It can be found from the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 1 in Table 1 that the antibacterial rates of Examples 1, 2, and 3 are high. The difference between Comparative Example 1 and the Examples is that guanidine is not grafted onto the surface of chitosan. Guanidine can specifically interact with a part of the bacterial ribosomal RNA, blocking the normal chain reaction required for protein synthesis; it can also interact with the circular structure of bacterial DNA, inhibiting the replication and reproduction of bacteria, thereby achieving the antibacterial effect.

[0053] It can be found from the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 2 that the antibacterial rates of Examples 1, 2, and 3 are high. The difference between Comparative Example 2 and the Examples is that chitosan is not modified and cannot react with bromine to form quaternary ammonium salts to change the cell membrane permeability: Quaternary ammonium salts can adsorb onto the surface of the bacterial cells, insert the hydrophobic group into the lipid layer, change the cell membrane permeability, destroy the membrane structure, cause the leakage of intracellular substances, affect the normal functions and metabolism of the cells, and can also denature proteins, resulting in cell death, thereby achieving the antibacterial effect.

[0054] It can be found from the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 3 that the antibacterial rates of Examples 1, 2, and 3 are high. The difference between Comparative Example 3 and the Examples is that iron ions and quaternary ammonium salts are not added. Iron ions carry a positive charge. When they come into contact with the cell membrane of microorganisms, they will have electrostatic attraction with the negatively charged cell membrane, penetrate the cell membrane and enter the bacteria, react with sulfhydryl groups, amino groups, etc. on the proteins in the bacteria, destroy the active center of the proteins, thereby causing cell death or loss of the ability to divide and proliferate, achieving the antibacterial effect.

[0055] Test Example 2:

[0056] Metal ion adsorption test:

[0057] Test method: At room temperature, add 1 g of the sewage treatment agent to 50 mL of a copper ion solution with a concentration of 20 mg / L, and detect the copper ion concentration after 60 min. The results are shown in Table 2.

[0058] Table 2

[0059] Copper ion concentration Example 1 0.8 mg / L Example 2 0.6 mg / L Example 3 0.7 mg / L Comparative Example 1 0.8 mg / L Comparative Example 2 5.8 mg / L Comparative Example 3 6.9 mg / L

[0060] It can be found from the comparison of the experimental data in Table 2 that the sewage treatment agent prepared by the present invention has good metal ion adsorption ability.

[0061] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 2 in Table 2, it can be found that the copper ion concentrations in Examples 1, 2 and 3 are low. The difference between Comparative Example 2 and the Examples is that chitosan was not modified, and carboxyl groups were introduced on its surface. The carboxyl functional group has strong electrophilic properties and can undergo a coordination reaction with metal ions to achieve the effect of adsorbing metal ions in sewage;

[0062] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 3, it can be found that the copper ion concentrations in Examples 1, 2 and 3 are low. The difference between Comparative Example 3 and the Examples is that silica was not modified, and the anthraquinone structure on the silica surface can complex with metal ions to achieve the effect of adsorbing metal ions in sewage.

[0063] Test Example 3:

[0064] Organic matter adsorption and degradation test:

[0065] Test method: First, prepare 25 mL each of 20 ppm eosin solution and methylene blue solution. Adjust the pH of the methylene blue solution to 5 with 0.1 mol / L acetic acid, then add 1 g of the sewage treatment agent, ultrasonicate, turn on the power of the photocatalytic device and irradiate for 60 min. Calculate the adsorption and degradation efficiency through the change in absorbance at 665 nm, where the adsorption and degradation efficiency = [(initial organic pollutant concentration - organic pollutant concentration after photocatalytic treatment) / initial organic pollutant concentration] × 100%; then perform the same treatment on the eosin solution. The results are shown in Table 3.

[0066] Table 3

[0067] Methylene blue adsorption and degradation efficiency Eosin adsorption and degradation efficiency Example 1 97.8％ 97.7％ Example 2 98.0％ 97.9％ Example 3 97.7％ 97.6％ Comparative Example 1 97.5％ 97.4％ Comparative Example 2 88.6％ 88.4％ Comparative Example 3 19.9％ 5.8％

[0068] From the comparison of the experimental data in Table 3, it can be found that the sewage treatment agent prepared by the present invention has good ability to adsorb and degrade organic pollutants.

[0069] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 2 in Table 3, it can be found that the methylene blue adsorption and degradation efficiency and eosin adsorption and degradation efficiency in Examples 1, 2 and 3 are high. The difference between Comparative Example 2 and the Examples is that chitosan was not modified, and the introduced phosphate ester hydrolyzes under acidic conditions to form phosphate anions, which can adsorb cationic pollutants in the water body, thereby accelerating the pollutant degradation efficiency. Moreover, the unmodified chitosan cannot react with the bromo groups on the surface of the modified silica to form quaternary ammonium salts. As cations, quaternary ammonium salts can well adsorb anionic pollutants in the water body, thereby accelerating the pollutant degradation efficiency;

[0070] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 3 in Table 3, it can be found that the methylene blue adsorption and degradation efficiency and eosin adsorption and degradation efficiency of Examples 1, 2, and 3 are high. The difference between Comparative Example 3 and the examples is that silica was not modified and iron ions were not introduced. Iron ions can degrade organic matter under photocatalytic conditions.

[0071] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sewage treatment agent, characterized in that: The sewage treatment agent is prepared by reacting modified silicon dioxide and functionalized chitosan, mixing with ferric acetate, and crushing. The functionalized chitosan is prepared by sequentially reacting chitosan with diethyl allyl phosphate, maleic anhydride and N-(2-mercapto)-guanidine; The modified silicon dioxide is prepared by reacting silicon dioxide with 3-bromopropyltrimethoxysilane, anthraquinone and 1,4-di(bromomethyl)benzene in sequence.

2. A method for preparing a sewage treatment agent, characterized in that: The preparation method of the sewage treatment agent mainly includes the following preparation steps: (1) N,N-dimethylformamide, maleic anhydride and sodium acetate are mixed in a molar ratio of 8 to 10:1:1, stirred at 200 to 300 r / min for 10 to 20 min, and pre-modified chitosan with a mass of 9 to 11 times that of maleic anhydride is added, heated to 85 to 95°C, and stirred for 5.5 to 6.5 h under nitrogen protection, and vacuum dried at -10 to 0°C for 22 to 26 h, washed with deionized water for 3 to 5 times, and then vacuum dried at -10 to 0°C for 22 to 26 h to obtain modified chitosan; (2) pre-modified silica, anthraquinone, 1,2-dichloroethane, ferric chloride, and 1,4-di(bromomethyl)benzene are mixed in a mass ratio of 8-10:1:65-75:0.5-0.7:5.5-5.8, stirred at 75-85°C, 200-300 r / min, under nitrogen protection for 22-26 hours, cooled to room temperature, filtered, washed with deionized water for 5-7 times, and vacuum dried at 55-65°C for 11-13 hours to obtain modified silica; (3) Modified silica, functionalized chitosan and N,N-dimethylformamide are mixed in a mass ratio of 1:1:8-12, heated to 55-65°C, stirred at 200-300 r / min for 12-13 h, added with a 20% ferric acetate ethanol solution of 0.2-0.3 times the mass of the modified silica, continued to stir for 15-25 min, cooled to room temperature, vacuum dried at 55-65°C for 22-26 h, crushed, and passed through a 5-mesh sieve to obtain a sewage treatment agent.

3. The method for preparing a sewage treatment agent according to claim 2, characterized in that: The pre-modified chitosan in step (1) is prepared by mixing diethyl allyl phosphate, chitosan and ethanol in a mass ratio of 1:2-3:16-20, stirring for 38-42 hours at 200-300 r / min, 45-55° C., under argon protection, filtering, washing with ethanol for 3-5 times, and vacuum drying at -10-0° C. for 11-13 hours.

4. The method for preparing a sewage treatment agent according to claim 3, characterized in that: The chitosan has a molecular weight of 2000.

5. The method for preparing a sewage treatment agent according to claim 2, characterized in that: The pre-modified silica in step (2) is prepared by mixing silica, 3-bromopropyltrimethoxysilane and isopropanol in a mass ratio of 1:0.14-0.16:10-12, adjusting the pH to 3.8-4.2 with 0.1 mol / L acetic acid solution, stirring at 85-95°C and 200-300 r / min for 5-7 hours, filtering, washing with deionized water for 3-5 times, and drying at 90-100°C for 2-4 hours.

6. The method for preparing a sewage treatment agent according to claim 2, characterized in that: The functionalized chitosan in step (3) is prepared by mixing modified chitosan, deionized water and azobisisobutyronitrile in a mass ratio of 1:18-22:0.05-0.07, stirring at 200-300 r / min for 2-3 min, adding an equal mass of N-(2-mercapto)-guanidine solution of the modified chitosan at a uniform speed within 5-7 min, stirring at 65-75° C. for 170-190 min, adding 0.2-0.3 times the mass of 2,6-di-tert-butyl-4-methylphenol solution of the modified chitosan, cooling to room temperature, filtering, washing with ethanol for 3-5 times, and vacuum drying at -10-0° C. for 22-26 h.

7. The method for preparing a sewage treatment agent according to claim 6, characterized in that: The N-(2-mercapto)-guanidine solution is prepared by uniformly mixing N-(2-mercapto)-guanidine and deionized water in a mass ratio of 1:8-10.

8. The method for preparing a sewage treatment agent according to claim 6, characterized in that: The 2,6-di-tert-butyl-4-methylphenol solution is prepared by uniformly mixing 2,6-di-tert-butyl-4-methylphenol and ethanol in a mass ratio of 1:8-12.

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