A combined treatment method of resin and electrooxidation for dimethylacetamide wastewater

Abstract

The present invention relates to the technical field of wastewater treatment, and specifically relates to a combined treatment method of resin and electrooxidation for dimethylacetamide wastewater. Its preparation process includes the following steps: crosslinking of lignocellulose and styrene particles; preparation of lignocellulose / vinylpyridine modified resin; preparation of acetamide adsorption resin; combined treatment of resin and electrooxidation for dimethylacetamide wastewater. After the crosslinking of lignocellulose and styrene, further crosslinking is carried out with vinylpyridine monomer, and a multi-dimensional crosslinked network resin grafted with lignocellulose and styrene with vinylpyridine as the substrate is formed, thereby significantly improving the adsorption efficiency of dimethylacetamide. Moreover, the groups in vinylpyridine can be introduced into the resin as functional groups, and lignocellulose contains active groups, and these groups can cooperate with the pyridine ring after crosslinking to further enhance the adsorption capacity of dimethylacetamide.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and particularly relates to a combined treatment method of resin and electro-oxidation for dimethylacetamide wastewater. Background Art

[0002] Dimethylacetamide (DMAC) is an important organic solvent, which is widely used in industries such as chemical engineering, pharmaceuticals, and fibers. DMAC poses great harm to aquatic organisms and human health. For example, DMAC wastewater usually contains a high concentration of organic matter and is difficult to be directly biodegradable; the molecular structure of DMAC is stable, and the effect of traditional biological treatment methods is not good. At present, common treatment methods include iron-carbon-Fenton oxidation, coagulation precipitation, anaerobic biochemical treatment, etc. However, these methods have problems such as high treatment cost and low efficiency. Therefore, the method of resin adsorption is also used to treat dimethylacetamide wastewater.

[0003] The existing resin adsorption for treating dimethylacetamide wastewater has the problem of limited adsorption capacity. For example, as mentioned in the patent publication CN118005864A, in the prior art, there are many drawbacks in the preparation method of the N,N-dimethylacetamide waste gas adsorption resin, including that the prepared adsorption resin contains impurities that affect the adsorption capacity for N,N-dimethylacetamide waste gas, etc. The solution proposed in the above patent is to adjust and control the production process parameters of the dimethylacetamide adsorption resin, so as to improve the adsorption capacity for dimethylacetamide. However, to greatly improve the adsorption of dimethylacetamide, the best method is to make the resin have a selective adsorption capacity for dimethylacetamide, so as to reduce the adsorption of other impurities while improving the adsorption effect on dimethylacetamide, and cooperate with other technologies to jointly treat dimethylacetamide wastewater step by step, so as to ensure the overall efficiency of wastewater treatment and ensure that the wastewater reaches a higher purification standard. Therefore, the present invention provides a resin with selective adsorption for dimethylacetamide, which improves the adsorption capacity of the resin for dimethylacetamide when treating dimethylacetamide wastewater, and is combined with electro-oxidation to solve the problems existing in the above prior art. Summary of the Invention

[0004] Aiming at the deficiencies existing in the prior art, the purpose of the present invention is to provide a combined treatment method of resin and electro-oxidation for dimethylacetamide wastewater.

[0005] A combined treatment method of resin and electro-oxidation for dimethylacetamide wastewater includes the following steps:

[0006] S1: Crosslinking of lignocellulose and styrene particles

[0007] Mix lignocellulose with deionized water, heat, and then add potassium persulfate, sodium dodecyl sulfate, and styrene monomer. After reaction, lignocellulose styrene crosslinked powder is obtained;

[0008] S2: Preparation of lignocellulose / vinylpyridine modified resin

[0009] The lignocellulose styrene cross-linked powder and vinylpyridine monomer are added to 1,2-dichloroethane for swelling, and then anhydrous ferric chloride, divinylbenzene cross-linking agent and initiator are added, and the reaction is carried out to obtain the lignocellulose / vinylpyridine modified resin;

[0010] S3: Preparation of acetamide adsorption resin

[0011] The lignocellulose / vinylpyridine modified resin is extracted to obtain the substrate resin. The substrate resin and 1,2-dichloroethane are added to the reaction flask for swelling, and then N-methylacetamide and anhydrous ferric chloride are added, and the reaction is carried out to prepare the acetamide adsorption resin;

[0012] S4: Combined treatment of resin and electrooxidation of dimethylacetamide wastewater

[0013] The dimethylacetamide wastewater is adsorbed by the acetamide adsorption resin to obtain the primary treated wastewater. The primary treated wastewater is degraded under the action of an electric field to obtain the degraded wastewater. The precipitate is removed from the degraded wastewater to complete the combined treatment of resin and electrooxidation of dimethylacetamide wastewater.

[0014] Further, the cross-linking of lignocellulose and styrene particles in step S1 includes the following steps:

[0015] S1.1: Mix lignocellulose and deionized water at a solid-liquid ratio of (1-3) g: 20 mL, heat to 80-90 °C, then stir at a speed of 300-350 r / min for 30-35 min, and then add potassium persulfate accounting for 3-5% of the total mass of the system, and keep stirring and reacting for 15-20 min;

[0016] S1.2: Subsequently, sodium dodecyl sulfate accounting for 2-3% of the total mass of the system is added, and then styrene monomer with the same mass as lignocellulose is added. Keep the temperature at 80-90 °C, and introduce nitrogen gas. Let it stand and react for 3-4 h, and then cool to room temperature of 22-24 °C. The product is precipitated, filtered, washed, and dried to constant weight in an oven at 60-65 °C to obtain the lignocellulose styrene cross-linked powder.

[0017] Further, the preparation of the lignocellulose / vinylpyridine modified resin in step S2 includes the following steps:

[0018] S2.1: Add 2-2.4 parts by mass of lignocellulose styrene cross-linked powder and 1.2-2 parts by mass of vinylpyridine monomer to 30-40 parts by mass of 1,2-dichloroethane, keep mechanical stirring at 300-350 r / min, and swell at room temperature for 12-13 h;

[0019] S2.2: Subsequently, weigh 4 - 8 parts by mass of anhydrous ferric chloride, 6 - 9 parts by mass of divinylbenzene crosslinking agent, and 0.5 - 2 parts by mass of initiator and add them to the reaction system. Raise the temperature to 50 - 60 °C and react for 2 - 2.5 h. Then raise the system temperature to 80 - 85 °C and react for 12 - 13 h. Maintain a nitrogen environment throughout the reaction process. Stop the reaction and cool to room temperature. Filter and wash with methanol until the filtrate is colorless. Dry the product in an oven at 60 - 65 °C to constant weight to obtain the lignocellulose / vinylpyridine modified resin.

[0020] Further, step S3 for preparing the acetamide adsorption resin includes the following steps:

[0021] S3.1: Place the lignocellulose / vinylpyridine modified resin in a Soxhlet extractor, extract with 90 - 95 wt% ethanol for 5 - 6 h, cool, take out and air-dry, then transfer to a vacuum drying oven and dry at 60 - 65 °C to constant weight. Place it in a sealed bag for storage to obtain the substrate resin;

[0022] S3.2: Add 20 - 25 parts by mass of the substrate resin and 30 - 40 parts by mass of 1,2 - dichloroethane to the reaction flask, swell for 8 - 9 h. Then add 2 - 3 parts by mass of N - methylacetamide to the reaction flask, stir at a speed of 300 - 350 r / min for 10 - 20 min. After the N - methylacetamide dissolves, add 5 - 8 parts by mass of anhydrous ferric chloride and continue to stir at a speed of 300 - 350 r / min for 2 - 2.5 h. Subsequently, heat the system to 80 - 85 °C and reflux for 12 - 13 h;

[0023] S3.3: After the reaction, cool to room temperature of 22 - 24 °C, filter with suction and wash with water. Place it in a Soxhlet extractor and extract with absolute ethanol for 12 - 13 h, cool, take out and air-dry, then transfer to a vacuum drying oven and vacuum-dry at 40 - 45 °C to constant weight to obtain the acetamide adsorption resin.

[0024] Further, step S4 for the combined treatment of the resin and electro-oxidation of dimethylacetamide wastewater includes the following steps:

[0025] S4.1: Filter the dimethylacetamide wastewater to remove the suspended solids therein, and then pass it through the acetamide adsorption resin at a flow rate of 0.5 - 3 BV / h for an adsorption time of 24 - 25 h to obtain the primary treated wastewater;

[0026] S4.2: Adjust the pH value of the primary treated wastewater to 2 - 4, use an electrocatalytic carbon membrane reactor, and carry out synergistic degradation in combination with persulfate. The reaction time is 30 - 60 min, and degrade the primary treated wastewater under the action of an electric field to obtain the degraded wastewater;

[0027] S4.3: Pass the degraded wastewater through a sedimentation tank to remove the sediment, thus completing the combined treatment of dimethylacetamide wastewater by resin and electrooxidation.

[0028] Further, the initiator is specifically azobisisobutyronitrile.

[0029] Further, the anode of the electrocatalytic carbon membrane reactor is made of titanium-based material, the cathode is made of carbon steel, and the current density of the electrocatalytic carbon membrane reactor is 10 - 50 mA / cm 2 , and the voltage is 10 - 20 V.

[0030] Further, the sulfate is specifically sodium persulfate.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] 1. After crosslinking lignocellulose with styrene, and then further crosslinking with vinylpyridine monomer, a multi-dimensional crosslinked network resin is formed with vinylpyridine as the substrate and lignocellulose and styrene grafted together. Such a multi-dimensional crosslinked network structure endows the resin with a high degree of crosslinking and good mechanical properties, namely, the ultra-high crosslinked resin. The ultra-high crosslinked resin can provide a large number of adsorption sites, thus significantly improving the adsorption efficiency of dimethylacetamide. Moreover, the groups in vinylpyridine can be introduced into the resin as functional groups, and lignocellulose contains active groups. After crosslinking, these groups can cooperate with the pyridine ring to further enhance the adsorption capacity of dimethylacetamide.

[0033] 2. By crosslinking the acetamide group of N-methylacetamide onto the vinylpyridine resin, the vinylpyridine resin is made to carry acetamide groups. The presence of N-methylacetamide groups increases the surface polarity of the resin, thus improving the adsorption capacity for polar organic substances. Moreover, after N-methylacetamide binds to vinylpyridine, the structure of the resin is optimized, and more adsorption sites can be provided, thus improving the adsorption efficiency. The functional groups in dimethylacetamide and the functional groups on the resin can be adsorbed through mutual interaction, thus improving the adsorption capacity of the resin for dimethylacetamide.

[0034] 3. By combining lignocellulose with styrene and modifying styrene with lignocellulose, the crosslinking reaction between lignocellulose and styrene can significantly improve the interfacial compatibility between the two. The components in lignocellulose can be combined with styrene through chemical bonds, thus reducing the repulsion between interfaces and enhancing the bonding performance between interfaces, thereby assisting in the formation of a multi-dimensional network structure and ultra-high crosslinked resin in subsequent steps. Moreover, lignocellulose is a natural and renewable biomass material, with wide sources and low prices. Using lignocellulose to modify styrene particles can reduce the dependence on petroleum-based materials, lower production costs, and reduce the impact on the environment at the same time.

[0035] 4. The present invention combines resin adsorption and electrooxidation to treat N,N-dimethylacetamide wastewater. The combined treatment of resin adsorption and electrooxidation can give full play to the advantages of both and achieve complementarity. Resin adsorption can be used as a pretreatment step for electrooxidation treatment to first remove most of the adsorbable pollutants in the wastewater and reduce the initial concentration of the wastewater. Electrooxidation can further degrade the refractory organic matter remaining after resin adsorption and decompose it into harmless small molecule substances, thereby achieving a more thorough purification effect. The overall efficiency of wastewater treatment can be effectively improved through the synergistic effect of resin adsorption and electrooxidation, ensuring that the wastewater meets higher purification standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings incorporated herein and constituting a part of the specification illustrate embodiments of the present disclosure and, together with the specification, are further used to explain the principles of the present disclosure and enable those skilled in the relevant art to implement and use the present disclosure.

[0037] Figure 1 It is a flow chart of a combined treatment method of resin and electrooxidation for N,N-dimethylacetamide wastewater adopted in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following describes in detail a combined treatment method of resin and electrooxidation for N,N-dimethylacetamide wastewater provided by the present invention with reference to the drawings and specific embodiments. At the same time, it should be noted here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments. For some well-known technologies, those skilled in the art can also adopt other alternative methods for implementation; moreover, the drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0039] Example 1: A combined treatment method of resin and electrooxidation for N,N-dimethylacetamide wastewater, as Figure 1 shown, includes the following steps:

[0040] S1: Crosslinking of lignocellulose and styrene particles

[0041] S1.1: Mix lignocellulose with deionized water at a solid-liquid ratio of 1 g:20 mL, heat to 80 °C, then stir at a speed of 300 r / min for 30 min, and then add potassium persulfate accounting for 3% of the total mass of the system, and maintain the stirring reaction for 15 min;

[0042] S1.2: Subsequently, add sodium dodecyl sulfate accounting for 2% of the total mass of the system, then add styrene monomer with the same mass as lignocellulose, keep the temperature at 80 °C, and introduce nitrogen gas, let it stand and react for 3 h, then cool to room temperature of 22 °C, precipitate and filter the product, wash it, and dry it to constant weight in an oven at 60 °C to obtain lignocellulose styrene crosslinked powder.

[0043] S2: Prepare lignocellulose / vinylpyridine modified resin

[0044] S2.1: Add 2 parts by mass of lignocellulose styrene cross-linked powder and 1.2 parts by mass of vinylpyridine monomer into 30 parts by mass of 1,2-dichloroethane, keep mechanical stirring at 300 r / min, and swell at room temperature for 12 h;

[0045] S2.2: Subsequently, weigh 4 parts by mass of anhydrous ferric chloride, 6 parts by mass of divinylbenzene cross-linking agent and 0.5 part by mass of initiator azobisisobutyronitrile and add them into the reaction system. Raise the temperature to 50 °C and react for 2 h. Then raise the system temperature to 80 °C and react for 12 h. Keep a nitrogen environment throughout the reaction process. Stop the reaction and cool to room temperature. Filter and wash with methanol until the filtrate is colorless. Dry the product in an oven at 60 °C to constant weight to obtain the lignocellulose / vinylpyridine modified resin.

[0046] S3: Prepare acetamide adsorption resin

[0047] S3.1: Place the lignocellulose / vinylpyridine modified resin in a Soxhlet extractor, extract with 90 wt% ethanol for 5 h, cool, take out and air dry, then transfer to a vacuum drying oven and dry at 60 °C to constant weight. Place it in a sealed bag for storage to obtain the substrate resin;

[0048] S3.2: Add 20 parts by mass of the substrate resin and 30 parts by mass of 1,2-dichloroethane into the reaction flask, swell for 8 h, then add 2 parts by mass of N-methylacetamide into the reaction flask, stir at a speed of 300 r / min for 10 min. After the N-methylacetamide is dissolved, add 5 parts by mass of anhydrous ferric chloride and continue to stir at a speed of 300 r / min for 2 h. Then heat the system to 80 °C and reflux for 12 h;

[0049] S3.3: After the reaction, cool to room temperature of 22 °C, filter with suction, wash with water, place in a Soxhlet extractor and extract with absolute ethanol for 12 h, cool, take out and air dry, then transfer to a vacuum drying oven and vacuum dry at 40 °C to constant weight to prepare the acetamide adsorption resin.

[0050] S4: Combined treatment of resin and electro-oxidation for dimethylacetamide wastewater

[0051] S4.1: Filter the dimethylacetamide wastewater to remove the suspended solids therein, and then pass it through the acetamide adsorption resin at a flow rate of 0.5 BV / h for 24 h of adsorption time to obtain the primary treated wastewater;

[0052] S4.2: Adjust the pH value of the primary treated wastewater to 2. Use an electrocatalytic carbon membrane reactor and combine it with persulfate sodium persulfate for synergistic degradation. The reaction time is 30 min. The anode of the electrocatalytic carbon membrane reactor is a titanium substrate, and the cathode is carbon steel. The current density of the electrocatalytic carbon membrane reactor is 10 mA / cm 2 , and the voltage is 10 V. Degrade the primary treated wastewater under the action of an electric field to obtain the degraded wastewater;

[0053] S4.3: Pass the degraded wastewater through a sedimentation tank to remove the precipitate, and complete the combined treatment of resin and electrooxidation of dimethylacetamide wastewater.

[0054] Example 2: A method for the combined treatment of resin and electrooxidation of dimethylacetamide wastewater, as Figure 1 shown, includes the following steps:

[0055] S1: Crosslink wood cellulose and styrene particles

[0056] S1.1: Mix wood cellulose and deionized water at a material-liquid ratio of 1 g: 20 mL, heat to 90 °C, then stir at a speed of 350 r / min for 35 min, and then add potassium persulfate accounting for 5% of the total system mass, and keep stirring and reacting for 20 min;

[0057] S1.2: Subsequently, add sodium dodecyl sulfate accounting for 2% of the total system mass, then add styrene monomer with the same mass as the wood cellulose, keep the temperature at 90 °C, and introduce nitrogen, let it stand and react for 4 h, then cool to room temperature of 24 °C, precipitate and filter the product, wash it, and dry it in an oven at 65 °C to constant weight to obtain wood cellulose styrene crosslinked powder.

[0058] S2: Prepare wood cellulose / vinylpyridine modified resin

[0059] S2.1: Add 2 parts by mass of wood cellulose styrene crosslinked powder and 1.2 parts by mass of vinylpyridine monomer to 30 parts by mass of 1,2-dichloroethane, keep mechanical stirring at 350 r / min, and swell at room temperature for 12 h;

[0060] S2.2: Subsequently, weigh 4 parts by mass of anhydrous ferric chloride, 6 parts by mass of divinylbenzene crosslinking agent and 0.5 part by mass of initiator azobisisobutyronitrile and add them to the reaction system. Raise the temperature to 60 °C and react for 2.5 h. Then raise the system temperature to 85 °C and react for 13 h. Keep a nitrogen environment throughout the reaction process. Stop the reaction and cool to room temperature, filter and wash with methanol until the filtrate is colorless, and dry the product in a drying oven at 65 °C to constant weight to obtain wood cellulose / vinylpyridine modified resin.

[0061] S3: Prepare acetamide adsorption resin

[0062] S3.1: Place the lignocellulose / vinylpyridine modified resin in a Soxhlet extractor, extract it with 95 wt% ethanol for 6 h, cool it, take it out and dry it in air, then transfer it to a vacuum drying oven and dry it at 65 °C until constant weight, and store it in a sealed bag to obtain the substrate resin;

[0063] S3.2: Add 25 parts by mass of the substrate resin and 40 parts by mass of 1,2-dichloroethane to the reaction flask, swell for 9 h, then add 3 parts by mass of N-methylacetamide to the reaction flask, stir at a speed of 350 r / min for 20 min, wait until N-methylacetamide is dissolved, add 5 parts by mass of anhydrous ferric chloride, continue to stir at a speed of 350 r / min for 2.5 h, then heat the system to 85 °C and reflux for 13 h;

[0064] S3.3: After the reaction is completed, cool it to room temperature (22 °C), filter it by suction and wash it with water, place it in a Soxhlet extractor and extract it with absolute ethanol for 13 h, cool it, take it out and dry it in air, then transfer it to a vacuum drying oven and dry it under vacuum at 45 °C until constant weight to obtain the acetamide adsorption resin.

[0065] S4: Combined treatment of resin and electrooxidation for dimethylacetamide wastewater

[0066] S4.1: Filter the dimethylacetamide wastewater to remove the suspended solids therein, and then pass it through the acetamide adsorption resin at a flow rate of 0.5 BV / h for 25 h of adsorption time to obtain the primary treated wastewater;

[0067] S4.2: Adjust the pH value of the primary treated wastewater to 2, use an electrocatalytic carbon membrane reactor, combine with persulfate sodium persulfate for synergistic degradation, the reaction time is 60 min, the anode of the electrocatalytic carbon membrane reactor is titanium-based, the cathode is carbon steel, and the current density of the electrocatalytic carbon membrane reactor is 50 mA / cm 2 , the voltage is 20 V, and the primary treated wastewater is degraded under the action of an electric field to obtain the degraded wastewater;

[0068] S4.3: Pass the degraded wastewater through a sedimentation tank to remove the precipitate, and complete the combined treatment of resin and electrooxidation for dimethylacetamide wastewater.

[0069] Example 3: A combined treatment method of resin and electrooxidation for dimethylacetamide wastewater, as Figure 1 shown, including the following steps:

[0070] S1: Crosslinking of lignocellulose and styrene particles

[0071] S1.1: Mix lignocellulose and deionized water at a material-liquid ratio of 3 g:20 mL, heat it to 80 °C, then stir it at a speed of 300 r / min for 30 min, and then add 5% of potassium persulfate based on the total mass of the system, and keep stirring and reacting for 15 min;

[0072] S1.2: Subsequently, add sodium dodecyl sulfate accounting for 3% of the total system mass, then add styrene monomer with the same mass as the lignocellulose. Keep the temperature at 80 °C, introduce nitrogen, and let it stand and react for 3 h. Subsequently, cool it to room temperature of 22 °C, precipitate and filter the product, wash it, and dry it in an oven at 60 °C until constant weight is achieved to obtain lignocellulose styrene cross-linked powder.

[0073] S2: Prepare lignocellulose / vinylpyridine modified resin

[0074] S2.1: Add 2.4 parts by mass of lignocellulose styrene cross-linked powder and 2 parts by mass of vinylpyridine monomer to 40 parts by mass of 1,2-dichloroethane. Keep mechanical stirring at 300 r / min and let it swell at room temperature for 12 h;

[0075] S2.2: Subsequently, weigh 8 parts by mass of anhydrous ferric chloride, 9 parts by mass of divinylbenzene cross-linking agent, and 2 parts by mass of initiator azobisisobutyronitrile and add them to the reaction system. Raise the temperature to 50 °C and react for 2 h. Then raise the system temperature to 80 °C and react for 12 h. Maintain a nitrogen environment throughout the reaction process. Stop the reaction and cool it to room temperature, filter it and wash it with methanol until the filtrate is colorless. Dry the product in a drying oven at 60 °C until constant weight is achieved to obtain lignocellulose / vinylpyridine modified resin.

[0076] S3: Prepare acetamide adsorption resin

[0077] S3.1: Place the lignocellulose / vinylpyridine modified resin in a Soxhlet extractor, extract it with 90 wt% ethanol for 5 h, cool it, take it out and let it dry in the air, then transfer it to a vacuum drying oven and dry it at 60 °C until constant weight is achieved. Place it in a sealed bag for storage to obtain the substrate resin;

[0078] S3.2: Add 25 parts by mass of the substrate resin and 40 parts by mass of 1,2-dichloroethane to the reaction flask, let it swell for 8 h, then add 3 parts by mass of N-methylacetamide to the reaction flask, stir at a speed of 300 r / min for 10 min. After the N-methylacetamide is dissolved, add 8 parts by mass of anhydrous ferric chloride and continue to stir at a speed of 300 r / min for 2 h. Subsequently, heat the system to 80 °C and reflux for 12 h;

[0079] S3.3: After the reaction, cool it to room temperature of 22 °C, filter it by suction and wash it with water. Place it in a Soxhlet extractor and extract it with absolute ethanol for 12 h, cool it, take it out and let it dry in the air, then transfer it to a vacuum drying oven and dry it at 40 °C under vacuum until constant weight is achieved to obtain the acetamide adsorption resin.

[0080] S4: Combined treatment of resin and electrooxidation for dimethylacetamide wastewater

[0081] S4.1: Filter the N,N-dimethylacetamide wastewater to remove the suspended solids therein, and then pass it through the acetamide adsorption resin at a flow rate of 0.5 BV / h for 24 h to obtain the primary treated wastewater;

[0082] S4.2: Adjust the pH value of the primary treated wastewater to 2, and use an electrocatalytic carbon membrane reactor to carry out synergistic degradation in combination with sodium persulfate. The reaction time is 30 min. The anode of the electrocatalytic carbon membrane reactor is a titanium substrate, and the cathode is carbon steel. The current density of the electrocatalytic carbon membrane reactor is 10 mA / cm 2 , and the voltage is 10 V. Degrade the primary treated wastewater under the action of an electric field to obtain the degraded wastewater;

[0083] S4.3: Pass the degraded wastewater through a sedimentation tank to remove the sediment, and complete the combined treatment of the N,N-dimethylacetamide wastewater by resin and electrooxidation.

[0084] Comparative Example 1: Compared with Example 1, the difference in Comparative Example 1 is that in step S2.1, instead of adding the cross-linked powder of lignocellulose and styrene, styrene is added. Specifically, "S2.1: Add 2 parts by mass of styrene and 1.2 parts by mass of vinylpyridine monomer to 30 parts by mass of 1,2-dichloroethane, maintain mechanical stirring at 300 r / min, and swell at room temperature for 12 h", and the remaining steps remain unchanged.

[0085] Comparative Example 2: Compared with Example 1, the difference in Comparative Example 2 is that in step S2.1, instead of adding the cross-linked powder of lignocellulose and styrene, lignocellulose is added. Specifically, "S2.1: Add 2 parts by mass of lignocellulose and 1.2 parts by mass of vinylpyridine monomer to 30 parts by mass of 1,2-dichloroethane, maintain mechanical stirring at 300 r / min, and swell at room temperature for 12 h", and the remaining steps remain unchanged.

[0086] Comparative Example 3: Compared with Example 1, the difference in Comparative Example 3 is that in step S2.1, the cross-linked powder of lignocellulose and styrene is not added. Specifically, "S2.1: Add 1.2 parts by mass of vinylpyridine monomer to 30 parts by mass of 1,2-dichloroethane, maintain mechanical stirring at 300 r / min, and swell at room temperature for 12 h;

[0087] S2.2: Subsequently, weigh 4 parts by mass of anhydrous ferric chloride, 6 parts by mass of divinylbenzene crosslinking agent, and 0.5 part by mass of initiator azodiisobutyronitrile and add them to the reaction system. Raise the temperature to 50 °C and react for 2 h. Then raise the system temperature to 80 °C and react for 12 h. Maintain a nitrogen environment throughout the reaction process. Stop the reaction and cool to room temperature. Filter and wash with methanol until the filtrate is colorless. Dry the product in an oven at 60 °C to constant weight to obtain vinylpyridine resin. Replace the lignocellulose / vinylpyridine modified resin in step S3 with vinylpyridine resin, and keep the other steps unchanged.

[0088] Comparative Example 4: Compared with Example 1, the difference in Comparative Example 4 is that N-methylacetamide is not added in step S3.2. Specifically, "S3.2: Add 20 parts by mass of substrate resin and 30 parts by mass of 1,2-dichloroethane to the reaction flask and swell for 8 h. Then add 2 parts by mass of N-methylacetamide to the reaction flask, stir at a speed of 300 r / min for 10 min. After the N-methylacetamide is dissolved, add 5 parts by mass of anhydrous ferric chloride and continue to stir at a speed of 300 r / min for 2 h. Subsequently, heat the system to 80 °C and reflux for 12 h", and keep the other steps unchanged.

[0089] Comparative Example 5: Compared with Example 1, the difference in Comparative Example 5 is that the dimethylacetamide wastewater is directly subjected to electro-oxidation treatment. Specifically, "Adjust the pH value of the dimethylacetamide wastewater to 2, use an electrocatalytic carbon membrane reactor, combine with persulfate for synergistic degradation, the reaction time is 30 min, degrade the dimethylacetamide wastewater under the action of an electric field to obtain the degraded wastewater, and pass the degraded wastewater through a sedimentation tank to remove the precipitate to complete the electro-oxidation treatment".

[0090] Comparative Example 6: Compared with Example 1, the difference in Comparative Example 6 is that the dimethylacetamide wastewater is directly subjected to resin adsorption treatment. Specifically, "Filter the dimethylacetamide wastewater to remove the suspended matter therein, and then pass it through an acetamide adsorption resin at a flow rate of 0.5 BV / h for 24 h to complete the resin adsorption treatment".

[0091] Take a total of 9 L of dimethylacetamide wastewater generated in the production process of a chemical enterprise, divide it into 9 equal parts (1 L each) and label them as Example 1-3 and Comparative Examples 1-6 respectively. Use high performance liquid chromatography to measure the dimethylacetamide content in the dimethylacetamide wastewater, and treat it by the methods in Example 1-3 and Comparative Examples 1-6. After treatment, use high performance liquid chromatography again to measure the dimethylacetamide content in the treated dimethylacetamide wastewater, and organize the detection data into a table as shown in Table 1.

[0092] Table 1

[0093] Content of dimethylacetamide before treatment (%) Content of dimethylacetamide after treatment (%) Example 1 35.42 1.26 Example 2 35.18 1.34 Example 3 35.61 1.24 Comparative Example 1 35.28 2.72 Comparative Example 2 35.63 3.84 Comparative Example 3 35.45 4.75 Comparative Example 4 35.14 6.83 Comparative Example 5 35.68 12.51 Comparative Example 6 35.49 11.67

[0094] As can be seen from Table 1, the dimethylacetamide contents in Examples 1, 2, and 3 are 1.26%, 1.34%, and 1.24% respectively. These values are relatively close, indicating that the experimental conditions and treatment methods in the examples have a certain stability and repeatability.

[0095] The dimethylacetamide content in Comparative Example 1 is 2.72%, indicating that after adding styrene instead of lignocellulose styrene cross-linked powder, the treatment effect of dimethylacetamide becomes worse; the dimethylacetamide content in Comparative Example 2 is 3.84%, and the dimethylacetamide content in Comparative Example 3 is 4.75%. It can be seen that after removing lignocellulose and styrene, the adsorption effect on the resin is affected. When lignocellulose and styrene are added simultaneously and lignocellulose / vinylpyridine modified resin is prepared using vinylpyridine as the substrate, the dimethylacetamide content in the wastewater decreases significantly, indicating that the adsorption effect of the resin has been significantly improved.

[0096] The dimethylacetamide content in Comparative Example 4 is 6.83%, indicating that without adding N-methylacetamide and without acetylamino groups cross-linking with the resin, the adsorption of the resin cannot selectively target dimethylacetamide, resulting in a significant reduction in the adsorption capacity for dimethylacetamide.

[0097] The dimethylacetamide contents in Comparative Example 5 and Comparative Example 6 are 12.51% and 11.67% respectively. It can be seen that the combined treatment of resin adsorption and electrooxidation can better reduce the dimethylacetamide content in dimethylacetamide wastewater and help the wastewater treatment reach a higher purification standard.

[0098] The above examples merely illustrate the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above examples without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the present invention.

Claims

1. A combined treatment method of resin and electrooxidation for dimethylacetamide wastewater, characterized in that, It includes the following steps: S1: Crosslinking of lignocellulose and styrene particles Mix lignocellulose with deionized water, heat it, then add potassium persulfate, sodium dodecyl sulfate and styrene monomer, and obtain lignocellulose styrene crosslinked powder after reaction; S2: Preparation of lignocellulose / vinylpyridine modified resin Swell the lignocellulose styrene crosslinked powder and vinylpyridine monomer in 1,2-dichloroethane, then add anhydrous ferric chloride, divinylbenzene crosslinking agent and initiator, and obtain lignocellulose / vinylpyridine modified resin after reaction; S3: Preparation of acetamide adsorption resin Extract the lignocellulose / vinylpyridine modified resin to obtain the substrate resin, add the substrate resin and 1,2-dichloroethane into the reaction flask, swell it, then add N-methylacetamide and anhydrous ferric chloride, and prepare the acetamide adsorption resin by reaction; S4: Combined treatment of resin and electrooxidation for dimethylacetamide wastewater Adsorb dimethylacetamide wastewater through the acetamide adsorption resin to obtain the primary treated wastewater, degrade the primary treated wastewater under the action of an electric field to obtain the degraded wastewater, and remove the precipitate from the degraded wastewater to complete the combined treatment of resin and electrooxidation for dimethylacetamide wastewater.

2. The resin and electro-oxidation combined treatment method for dimethylacetamide wastewater according to claim 1, wherein Step S1 for crosslinking of lignocellulose and styrene particles includes the following steps: S1.1: Mix lignocellulose with deionized water at a material-liquid ratio of (1-3) g: 20 mL, heat it to 80-90 °C, then stir it at a speed of 300-350 r / min for 30-35 min, and then add potassium persulfate accounting for 3-5% of the total mass of the system, and keep stirring and reacting for 15-20 min; S1.2: Then add sodium dodecyl sulfate accounting for 2-3% of the total mass of the system, and then add styrene monomer with the same mass as lignocellulose, keep the temperature at 80-90 °C, and introduce nitrogen, let it stand and react for 3-4 h, then cool it to room temperature of 22-24 °C, precipitate and filter the product, wash it, and dry it to constant weight in an oven at 60-65 °C to obtain lignocellulose styrene crosslinked powder.

3. The resin and electro-oxidation combined treatment method for dimethylacetamide wastewater according to claim 2, characterized in that, Step S2 for preparing lignocellulose / vinylpyridine modified resin includes the following steps: S2.1: Add 2-2.4 parts by mass of lignocellulose styrene crosslinked powder and 1.2-2 parts by mass of vinylpyridine monomer into 30-40 parts by mass of 1,2-dichloroethane, keep mechanical stirring at 300-350 r / min, and swell at room temperature for 12-13 h; S2.2: Then weigh 4-8 parts by mass of anhydrous ferric chloride, 6-9 parts by mass of divinylbenzene crosslinking agent and 0.5-2 parts by mass of initiator and add them into the reaction system, raise the temperature to 50-60 °C, react for 2-2.5 h, raise the temperature of the system to 80-85 °C, react for 12-13 h, keep a nitrogen environment throughout the reaction process, stop the reaction and cool it to room temperature, filter and wash it with methanol until the filtrate is colorless, and dry the product to constant weight in a drying oven at 60-65 °C to obtain lignocellulose / vinylpyridine modified resin.

4. The resin and electrooxidation combined treatment method for dimethylacetamide wastewater according to claim 3, wherein Step S3 for preparing acetamide adsorption resin includes the following steps: S3.1: Place the lignocellulose / vinylpyridine modified resin in a Soxhlet extractor, extract it with 90 - 95 wt% ethanol for 5 - 6 h, cool it, take it out, dry it in air, then transfer it to a vacuum drying oven and dry it at 60 - 65 °C until constant weight, and store it in a sealed bag to obtain the substrate resin; S3.2: Add 20 - 25 parts by mass of the substrate resin and 30 - 40 parts by mass of 1,2 - dichloroethane to a reaction flask, swell for 8 - 9 h, then add 2 - 3 parts by mass of N - methylacetamide to the reaction flask, stir at a speed of 300 - 350 r / min for 10 - 20 min. After the N - methylacetamide is dissolved, add 5 - 8 parts by mass of anhydrous ferric chloride, continue to stir at a speed of 300 - 350 r / min for 2 - 2.5 h, then heat the system to 80 - 85 °C and reflux for 12 - 13 h; S3.3: After the reaction is completed, cool it to room temperature (22 - 24 °C), filter it by suction, wash it with water, place it in a Soxhlet extractor and extract it with absolute ethanol for 12 - 13 h, cool it, take it out, dry it in air, then transfer it to a vacuum drying oven and dry it under vacuum at 40 - 45 °C until constant weight to obtain the acetamide - adsorbed resin.

5. The resin and electro-oxidation combined treatment method for dimethylacetamide wastewater according to claim 4, wherein, Step S4: The combined treatment of the resin and electro - oxidation of dimethylacetamide wastewater includes the following steps: S4.1: Filter the dimethylacetamide wastewater to remove the suspended solids therein, and then pass it through the acetamide - adsorbed resin at a flow rate of 0.5 - 3 BV / h for an adsorption time of 24 - 25 h to obtain the primary treated wastewater; S4.2: Adjust the pH value of the primary treated wastewater to 2 - 4, use an electro - catalytic carbon - membrane reactor, and combine with persulfate for synergistic degradation. The reaction time is 30 - 60 min, and degrade the primary treated wastewater under the action of an electric field to obtain the degraded wastewater; S4.3: Pass the degraded wastewater through a sedimentation tank to remove the precipitate, and complete the combined treatment of the resin and electro - oxidation of dimethylacetamide wastewater.

6. The resin and electro-oxidation combined treatment method for dimethylacetamide wastewater according to claim 3, characterized in that, The initiator is specifically azobisisobutyronitrile.

7. The resin and electro-oxidation combined treatment method for dimethylacetamide wastewater according to claim 5, characterized in that, The anode of the electrocatalytic carbon membrane reactor is made of titanium-based material, the cathode is made of carbon steel, and the current density of the electrocatalytic carbon membrane reactor is 10 - 50 mA / cm 2 , and the voltage is 10 - 20 V.

8. The resin and electro-oxidation combined treatment method for dimethylacetamide wastewater according to claim 5, wherein, The sulfate is specifically sodium persulfate.

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