Iron-nitrogen-carbon-based magnetic material for synchronously removing combined pollution of iron and ibuprofen drugs in underground water and application of iron-nitrogen-carbon-based magnetic material

Abstract

The invention relates to an iron-nitrogen-carbon-based magnetic material for synchronously removing combined pollution of iron and ibuprofen drugs in underground water and an application of the iron-nitrogen-carbon-based magnetic material. The material can stably adsorb iron ions in water through a surface carboxyl complexing way, and the adsorbed iron ions are used as a medium to fix carboxyl groups of ibuprofen drugs on the surface of the material, so that the effect of synchronously adsorbing and removing iron and ibuprofen drugs in water is realized. The method is suitable for synchronous adsorption removal of polymorphic iron and various ibuprofen drugs; an N site and a defect site are successfully introduced in a material synthesis stage and jointly play a role in catalyzing ozone to generate strong oxidation free radicals. The iron-nitrogen-carbon-based magnetic material is combined with O3, so that the drug removal rate and the ozone utilization rate can be greatly improved, and meanwhile, the regeneration of drug adsorption sites is completed. On the basis, under the working condition that 0.4 mg / L ozone is introduced, more than 90% of the 1.0 mg / L ibuprofen medicine can be removed by only consuming 5 minutes in the process.

Description

Technical Field

[0001] This invention relates to an iron-nitrogen-carbon-based magnetic material and its application for simultaneously removing combined contamination of iron and ibuprofen-like drugs from groundwater, belonging to the field of groundwater treatment technology. Background Technology

[0002] Groundwater is a vital water source in northern my country, and safeguarding its security is of practical significance for ensuring the economic and social development of the region. The combined pollution of iron and human / veterinary drugs is a typical characteristic of groundwater pollution in northern China. Developing simultaneous and efficient removal technologies for iron and ibuprofen-like drugs from water is crucial for improving the urban water environment in northern China that relies on groundwater.

[0003] Currently, technologies for the simultaneous treatment of combined iron and drug pollution in groundwater include ozone methods, heterogeneous catalytic ozone methods, and combined ozone and activated carbon methods. Ozone methods are selective for drug types; for example, the removal efficiency of ibuprofen and other profen-like drugs is generally low due to the presence of carboxyl groups. Heterogeneous catalytic ozone methods, characterized by the addition of solid catalysts, can remove ibuprofen and other profen-like drugs. However, this process removes iron by rapidly oxidizing the main iron component in groundwater, ferrous iron (Fe2+), to ferric iron (Fe3+), which then precipitates as Fe(OH)3. Ferrous iron has poor catalytic activity against ozone, and the precipitated Fe(OH)3 easily adheres to the surface of the solid catalyst, hindering its function and thus affecting the removal rate of profen-like drugs. The combined ozone and activated carbon method also suffers from the problem of rapid conversion of ferrous iron to Fe(OH)3 precipitate, which masks the adsorption sites of activated carbon and slows down the removal rate of profen-like drugs. Furthermore, the removal of profen-like drugs in ozone and activated carbon processes also faces problems such as activated carbon adsorption saturation, poor in-situ regeneration of activated carbon, and secondary pollution from waste carbon. In summary, there is an urgent need to develop an efficient, stable, and environmentally friendly solution for the combined pollution of groundwater by iron and ibuprofen-like drugs. Summary of the Invention

[0004] To address the problems of existing technologies, this invention incorporates research and technological innovation. Both ferrous (Fe2+) and ferric (Fe3+) ions in water possess strong complexing properties with carboxyl groups. By synthesizing a functional material rich in carboxyl groups, immobilizing iron ions from water onto the material's surface, and then utilizing the complexing effect of the surface-immobilized iron with the carboxyl groups of profen-like drugs to remove the drugs from the water, simultaneous adsorption and removal of iron and profen-like drugs can be achieved. To solve the adsorption saturation problem, by introducing active iron, N-sites, defect sites, and other sites with ozone-catalyzing properties onto the material surface during the material synthesis stage, and then placing the material adsorbed with iron and profen-like drugs in an ozone environment, the catalytic properties of the material can convert ozone into highly oxidizing reactive oxygen species, achieving complete drug decomposition and regeneration of surface adsorption sites.

[0005] Due to the ozone-catalyzing properties of the material, this technology enhances the removal efficiency of profen-like drugs, improves ozone utilization, and significantly reduces ozone energy consumption compared to ozone-only processes. Because this technology uses a carboxyl complexation pathway to remove iron, the valence state of iron ions does not affect the complexation reaction. No Fe(OH)3 precipitate forms on the material surface after contact with ozone, making it less likely to mask reactive sites. This gives this technology an advantage over heterogeneous catalytic ozone methods and combined ozone-activated carbon methods in removing profen-like drugs.

[0006] To synthesize a material that meets the aforementioned functional requirements, this invention provides a synthetic approach for iron-nitrogen-carbon-based magnetic materials. Iron salts and benzoic acid ligands can synthesize an iron-carbon-based material with a large specific surface area and a surface rich in carboxyl groups at room temperature. Iron salts and imidazole rings rich in N sites also exhibit excellent coordination effects at room temperature, enabling the introduction of N sites onto the surface of the aforementioned iron-carbon-based material. Through ball milling, oxygen-deficient heat treatment, and other methods, abundant active iron and defect sites can be constructed on the material surface, further endowing the iron-based material with paramagnetic properties and enhancing its recyclability. Ultimately, an iron-nitrogen-carbon-based magnetic material combining iron and profenofibrate adsorption effects with ozone catalytic effects is synthesized.

[0007] The first objective of this invention is to provide an iron-nitrogen-carbon-based magnetic material that can simultaneously remove combined contamination from groundwater by iron and profen-like drugs. The preparation steps of the iron-nitrogen-carbon-based magnetic material are as follows:

[0008] 1) Dissolve ferrous salts in a solvent to obtain an iron-containing solution with an iron concentration of 0.1–0.6 mol / L;

[0009] 2) Mix aromatic carboxylic acid, 2-methylimidazole and 1-methylimidazole in a molar ratio of (2-4):1:1 and dissolve them in a solvent to obtain a ligand solution;

[0010] 3) Add the iron-containing solution from step 1) dropwise into the ligand solution from step 2), and then continuously stir the mixture at 200-400 rpm for 12-24 h;

[0011] 4) Centrifuge the mixture from step 3) to obtain insoluble matter. Wash the insoluble matter with methanol, wash with water and vacuum dry it in sequence. Place the insoluble matter in a zirconia ball mill jar and ball mill the sample at 400-600 rpm for 4-6 h. The mass ratio of sample:zirconia balls:water in the zirconia ball mill jar is (1-3):6:2.

[0012] 5) Place the ball-milled sample obtained in step 4) in a tube furnace and heat it in a nitrogen atmosphere at 500-800℃ for 2-6 h to obtain a black iron-nitrogen-carbon based magnetic material.

[0013] Step 1) The divalent ferric salt is ferrous sulfate, ferrous nitrate, ferrous chloride, or a hydrate of the above ferric salts.

[0014] Step 2) The aromatic carboxylic acid is benzoic acid, phthalic acid, isophthalic acid, terephthalic acid or pyromellitic acid.

[0015] The solvents used in steps 1) and 2) are methanol, water, or dimethylformamide.

[0016] The molar ratio of the iron concentration in the iron-containing solution in step 1) to the organic ligand concentration in the ligand solution in step 2) is (1-6):8.

[0017] The volume ratio of the iron-containing solution in step 1) to the ligand solution in step 2) is (1-2):2.

[0018] The processes described in steps 1-3) are all operated under nitrogen protection or vacuum conditions.

[0019] The second objective of this invention is to provide a method for simultaneously removing combined contamination from groundwater by iron and profen-like drugs. The method comprises the following steps:

[0020] a. Adjust the pH of the groundwater to 5.5-8.5, and pump the groundwater containing 0.2-2.0 mg / L iron ions and 0.2-2.0 mg / L profen-like drugs into a PP cotton filter;

[0021] b. Inject the filtered groundwater from step a into an integrated iron and drug removal reactor, turn on the stirrer in the reactor, and use the iron-nitrogen-carbon-based magnetic material in the reactor to adsorb iron ions in the water. At the same time, the adsorbed iron ions complex the ibuprofen-like drugs in the water and fix the drugs on the surface of the material. The mass ratio of the iron-nitrogen-carbon-based magnetic material to the water volume in the reactor is 10-100 mg: 1L. The running time of this adsorption stage is 20-40 min.

[0022] c. Add 0.2-0.6 mg / L ozone into the reactor described in step b. Utilize the catalytic properties of the iron-nitrogen-carbon-based magnetic material in the reactor to achieve the complete decomposition of ibuprofen drugs and the regeneration of adsorption sites. The running time of this ozonation stage is 10-20 min.

[0023] d. Turn on the electromagnet for 5-15 minutes to recover the iron-nitrogen-carbon-based magnetic material in the reactor;

[0024] e. The reactor effluent is filtered twice through a PP cotton filter before being discharged.

[0025] The iron ions mentioned in step a are ferrous iron (Fe2+) or ferric iron (Fe3+), and the profen drugs are drugs with typical aromatic acrylic acid structures such as ibuprofen, ketoprofen, piprofen, loxoprofen, or pranoprofen.

[0026] The beneficial effects of this invention are:

[0027] (1) This invention provides an iron-nitrogen-carbon-based magnetic material. This material can stably adsorb iron ions in water through surface carboxyl complexation, and use the adsorbed iron ions as a medium to fix the carboxyl groups of profen drugs on the material surface, thereby achieving the effect of simultaneous adsorption and removal of iron and profen drugs from water. The crystallization of the material is completed at room temperature, and the raw materials are inexpensive and readily available; it has a large adsorption capacity for iron and profen drugs, and is suitable for the simultaneous adsorption and removal of various forms of iron and various profen drugs; it is paramagnetic, which facilitates separation and recovery from water.

[0028] (2) This invention provides an integrated process of iron-nitrogen-carbon-based magnetic materials / O3, which further enhances the removal of iron and profen-like drugs from groundwater, significantly reducing process energy consumption and floor space. During the material synthesis stage, N-sites and defect sites were successfully introduced, both of which catalyze the generation of strong oxidizing free radicals from ozone. Combining iron-nitrogen-carbon-based magnetic materials with O3 can significantly improve drug removal rate and ozone utilization, while simultaneously regenerating drug adsorption sites. Based on this, under the condition of introducing 0.4 mg / L ozone, the process achieves a removal rate of over 90% for 1.0 mg / L profen-like drugs in just 5 minutes. Attached Figure Description

[0029] Figure 1 These are scanning electron microscope images and elemental distribution diagrams of the iron-nitrogen-carbon-based magnetic material prepared in Example 1.

[0030] Figure 2 This describes the magnetic separation effect of the iron-nitrogen-carbon-based magnetic material prepared in Example 1.

[0031] Figure 3 This is a schematic diagram of the device used in Examples 4, 5, and 6. In the diagram: 1. Raw water tank; 2. PP cotton filter; 3. Integrated iron and drug removal reactor; 4. Stirrer; 5. Iron-nitrogen-carbon based magnetic material; 6. Ozone generator; 7. Electromagnet; 8. PP cotton filter.

[0032] Figure 4 This figure shows the effect of the iron-nitrogen-carbon-based magnetic material prepared in Example 1 on the removal of iron ions in water according to the steps in Example 4. In the figure, a shows the result of the iron-nitrogen-carbon-based magnetic material removing iron ions in the system where ferrous iron and ibuprofen coexist; b shows the result of the iron-nitrogen-carbon-based magnetic material removing iron ions in the system where ferric iron and ibuprofen coexist.

[0033] Figure 5This figure shows the removal effect of the iron-nitrogen-carbon-based magnetic material prepared in Example 1 on the adsorption stage of ibuprofen in water according to the steps of Example 4. In the figure, a represents the adsorption result of ibuprofen by the iron-nitrogen-carbon-based magnetic material in the coexistence system of ferrous iron and ibuprofen; b represents the adsorption result of ibuprofen by the iron-nitrogen-carbon-based magnetic material in the coexistence system of ferric iron and ibuprofen; c represents the adsorption result of ibuprofen by the iron-nitrogen-carbon-based magnetic material alone in the absence of iron ions; and d represents the blank result of the coexistence system of ferrous iron and ibuprofen without the addition of iron-nitrogen-carbon-based magnetic material.

[0034] Figure 6 This figure shows the removal effect of the iron-nitrogen-carbon-based magnetic material prepared in Example 1 on the ozonation stage of ibuprofen in water according to the steps of Example 4. In the figure, a represents the ozonation result of ibuprofen by the iron-nitrogen-carbon-based magnetic material in the coexistence system of ferrous iron and ibuprofen; b represents the ozonation result of ibuprofen by the iron-nitrogen-carbon-based magnetic material in the coexistence system of ferric iron and ibuprofen; c represents the ozonation result of ibuprofen by the iron-nitrogen-carbon-based magnetic material alone in the absence of iron ions; d represents the ozonation result of ibuprofen without the addition of iron-nitrogen-carbon-based magnetic material in the coexistence system of ferrous iron and ibuprofen; and e represents the ozonation result of ibuprofen without the addition of iron-nitrogen-carbon-based magnetic material in the coexistence system of ferric iron and ibuprofen. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The described embodiments are only some, not all, of the embodiments of the present invention. Other embodiments obtained without creative effort are all within the protection scope of the present invention.

[0036] Example 1:

[0037] The preparation steps of iron-nitrogen-carbon based magnetic materials are as follows:

[0038] 1) Under nitrogen protection, FeSO4·7H2O was dissolved in methanol to obtain an iron-containing solution with an iron concentration of 0.35 mol / L.

[0039] 2) Under nitrogen protection, pyromellitic acid, 2-methylimidazole and 1-methylimidazole were mixed in a molar ratio of 3:1:1 and dissolved in methanol to obtain a ligand solution with a concentration of 0.8 mol / L.

[0040] 3) Under nitrogen protection, the iron-containing solution from step 1) was added dropwise to the ligand solution from step 2), with a volume ratio of 3:4 between the iron-containing solution and the ligand solution; then the mixture was stirred continuously at 300 rpm for 18 h.

[0041] 4) Centrifuge the mixture from step 3) to obtain insoluble matter. Wash the insoluble matter sequentially with methanol, water, and vacuum dry. Place the insoluble matter in a zirconia ball mill jar and ball mill the sample at 500 rpm for 5 h. The mass ratio of sample:zirconia balls:water in the zirconia ball mill jar is 1:3:1.

[0042] 5) Place the ball-milled sample obtained in step 4) in a tube furnace and heat it at 650°C in a nitrogen atmosphere for 4 h to obtain a black iron-nitrogen-carbon based magnetic material.

[0043] Figure 1 The images show scanning electron microscope (SEM) images and elemental distribution diagrams of the iron-nitrogen-carbon-based magnetic material prepared in Example 1. As can be seen from the images, the prepared iron-nitrogen-carbon-based magnetic material consists of blocky, irregular particles, with iron, nitrogen, and carbon elements evenly distributed on the material surface.

[0044] Figure 2 This shows the magnetic separation effect of the iron-nitrogen-carbon-based magnetic material prepared in Example 1. It can be seen that the black iron-nitrogen-carbon-based magnetic material is easily separated from water under an applied magnetic field.

[0045] Example 2:

[0046] The preparation steps of iron-nitrogen-carbon based magnetic materials are as follows:

[0047] 1) Under vacuum conditions, Fe(NO3)2·6H2O was dissolved in water to obtain an iron-containing solution with an iron concentration of 0.1 mol / L.

[0048] 2) Under vacuum conditions, benzoic acid, 2-methylimidazole and 1-methylimidazole were mixed in a molar ratio of 2:1:1 and dissolved in water to obtain a ligand solution with a concentration of 0.8 mol / L.

[0049] 3) Under vacuum conditions, the iron-containing solution from step 1) is added dropwise to the ligand solution from step 2), with a volume ratio of 1:2 between the iron-containing solution and the ligand solution; then the mixture is stirred continuously at 200 rpm for 12 h.

[0050] 4) Centrifuge the mixture from step 3) to obtain insoluble matter. Wash the insoluble matter sequentially with methanol, water, and vacuum dry. Place the insoluble matter in a zirconia ball mill jar and ball mill the sample at 400 rpm for 4 hours. The mass ratio of sample:zirconia balls:water in the zirconia ball mill jar is 1:6:2.

[0051] 5) Place the ball-milled sample obtained in step 4) in a tube furnace and heat it at 500°C in a nitrogen atmosphere for 2 h to obtain a black iron-nitrogen-carbon based magnetic material.

[0052] Example 3:

[0053] The preparation steps of iron-nitrogen-carbon based magnetic materials are as follows:

[0054] 1) Under nitrogen protection, FeCl2 was dissolved in dimethylformamide to obtain an iron-containing solution with an iron concentration of 0.6 mol / L.

[0055] 2) Under nitrogen protection, phthalic acid, 2-methylimidazole and 1-methylimidazole were mixed in a molar ratio of 4:1:1 and dissolved in dimethylformamide to obtain a ligand solution with a concentration of 0.8 mol / L.

[0056] 3) Under nitrogen protection, the iron-containing solution from step 1) was added dropwise to the ligand solution from step 2), with a volume ratio of 1:1 between the iron-containing solution and the ligand solution; then the mixture was stirred continuously at 400 rpm for 24 h.

[0057] 4) Centrifuge the mixture from step 3) to obtain insoluble matter. Wash the insoluble matter sequentially with methanol, water, and vacuum dry. Place the insoluble matter in a zirconia ball mill jar and ball mill the sample at 600 rpm for 6 hours. The mass ratio of sample:zirconia balls:water in the zirconia ball mill jar is 3:6:2.

[0058] 5) Place the ball-milled sample obtained in step 4) in a tube furnace and heat it at 800°C in a nitrogen atmosphere for 6 h to obtain a black iron-nitrogen-carbon based magnetic material.

[0059] Example 4:

[0060] The schematic diagram of the device used in this embodiment is shown below. Figure 3 As shown. The operating process of the device is as follows: Groundwater containing iron ions and ibuprofen-like drugs in the raw water tank 1 is filtered through a PP cotton filter 2 and then injected into the integrated iron and drug removal reactor 3; then, the stirrer 4 in the reactor 3 is turned on, and the iron-nitrogen-carbon-based magnetic material 5 in the reactor 3 adsorbs iron ions in the water, while the adsorbed iron ions complex ibuprofen-like drugs in the water, fixing the drugs on the surface of the iron-nitrogen-carbon-based magnetic material 5; then, the ozone generator 6 is turned on to add ozone into the reactor 3, and the catalytic ozone properties of the iron-nitrogen-carbon-based magnetic material 5 are used to achieve the complete decomposition of ibuprofen-like drugs and the regeneration of adsorption sites; then, the electromagnet 7 is turned on to recover the iron-nitrogen-carbon-based magnetic material 5; finally, the effluent from the reactor 3 is filtered through a PP cotton filter 8 and then discharged.

[0061] The method for simultaneously removing combined pollution of iron and ibuprofen-like drugs from groundwater using iron-nitrogen-carbon based magnetic materials is carried out according to the following steps:

[0062] a. Adjust the pH of the groundwater to 7.0, and pump the groundwater containing 1.0 mg / L iron ions (ferrous or ferric) and 1.0 mg / L ibuprofen into the PP cotton filter.

[0063] b. Inject the filtered groundwater from step a into an integrated iron and drug removal reactor. Turn on the agitator inside the reactor. The iron-nitrogen-carbon-based magnetic material inside the reactor adsorbs iron ions in the water. Simultaneously, the adsorbed iron ions complex the ibuprofen-like drugs in the water, fixing the drugs onto the surface of the material. The mass ratio of the iron-nitrogen-carbon-based magnetic material to the water volume in the reactor is 50 mg: 1 L. This stage takes 30 minutes to run.

[0064] c. Add 0.4 mg / L ozone to the reactor described in step b. Utilize the catalytic properties of the iron-nitrogen-carbon-based magnetic material within the reactor to achieve the complete decomposition of ibuprofen-like drugs and the regeneration of adsorption sites. This stage takes 15 minutes.

[0065] d. Turn on the electromagnet for 10 minutes to recover the iron-nitrogen-carbon-based magnetic material in the reactor.

[0066] e. The reactor effluent is filtered twice through a PP cotton filter before being discharged.

[0067] Figure 4 The removal effect of the iron-nitrogen-carbon-based magnetic material prepared in Example 1 on iron ions in water was investigated according to the steps in Example 4. In step b, the adsorption stage, the total iron concentration in the effluent from both the ferrous (Fe2+) and ferric (Fe3+) systems decreased significantly with increasing adsorption time. After 20 min of adsorption, the total iron concentration in the effluent from the ferrous (Fe2+) system was below the national standard limit of 0.3 mg / L (Class III water requirement of the Groundwater Quality Standard (GBT14848-2017)). Further increasing the adsorption time to 30 min, the total iron concentration in the ferric (Fe3+) system also met the standard. In step c, the ozonation stage, iron ions in the water were further removed. After ozonation for 15 min, the total iron concentration in the effluent from the ferric (Fe3+) system decreased to 0.18 mg / L, and the total iron concentration in the effluent from the ferrous (Fe2+) system decreased to 0.01 mg / L. Both were significantly lower than the national standard limit of 0.3 mg / L.

[0068] Figure 5 The removal effect of the iron-nitrogen-carbon-based magnetic material prepared in Example 1 on the adsorption stage of ibuprofen in water was compared with that in Example 4. Figure 5 The study also included an adsorption experiment of ibuprofen in water by ferric-nitrogen-carbon-based magnetic materials in the absence of ferric ions (curve c), and a control experiment in the presence of ferrous ions without the addition of ferric-nitrogen-carbon-based magnetic materials (curve d). Figure 5As shown, when ferrous ions coexist with ibuprofen in water, there is virtually no removal of ibuprofen (curve d). In the absence of ferrous ions, the iron-nitrogen-carbon-based magnetic material can only adsorb about 30% of ibuprofen, and this adsorption process takes about 30 minutes (curve c). In contrast, the iron-nitrogen-carbon-based magnetic material adsorbing ferrous or ferric ions can adsorb about 60% of ibuprofen, and this adsorption process is basically completed within 20 minutes (curves a and b). Therefore, ferrous ions, which are originally the target for removal, have a significantly enhanced effect on the adsorption and removal of ibuprofen-like drugs in water after being adsorbed and complexed on the surface of the iron-nitrogen-carbon-based magnetic material.

[0069] Figure 6 The iron-nitrogen-carbon-based magnetic material prepared in Example 1 was used to remove ibuprofen from water during the ozonation stage, following the steps in Example 4. As a comparison, Figure 6 The study also included an ozonation removal experiment of ibuprofen from water using iron-nitrogen-carbon-based magnetic materials in the absence of iron ions (curve c), and an ozonation experiment without the addition of iron-nitrogen-carbon-based magnetic materials in the presence of iron ions (curves d and e). The results are as follows... Figure 6 As shown, without the addition of iron-nitrogen-carbon-based magnetic materials, the removal efficiency of ibuprofen by ferrous iron / O3 and ferric iron / O3 was relatively slow (curves d and e), and the effect of ferric iron / O3 was worse than that of ferrous iron / O3. This is related to the fact that ferrous iron has a certain ability to enhance ozone oxidation. In the absence of iron ions, the iron-nitrogen-carbon-based magnetic materials / O3 can improve the ibuprofen removal efficiency to a certain extent, and the ibuprofen removal rate can be increased to 70% after 15 minutes of reaction (curve c). Considering that the iron-nitrogen-carbon-based magnetic materials remove approximately 30% of the ibuprofen during the adsorption stage... Figure 5 This indicates that the invented iron-nitrogen-carbon-based magnetic material possesses the dual functions of adsorbing ibuprofen and catalyzing the oxidation of ibuprofen by ozone. In contrast, in a system where iron and ibuprofen coexist, combining the iron-nitrogen-carbon-based magnetic material, which has already adsorbed both iron and ibuprofen, with O3 to remove ibuprofen, can increase the ibuprofen removal rate to 90% within 5 minutes (curves a and b). This is because after the iron-nitrogen-carbon-based magnetic material adsorbs iron ions in the water, the material adsorbs ibuprofen (60%). Figure 5 The dual effects of ionization and catalytic ozone oxidation of ibuprofen are further enhanced, ultimately achieving ultra-fast removal of ibuprofen from water.

[0070] Table 1 shows the overall removal effect of the iron-nitrogen-carbon-based magnetic material prepared in Example 1 on iron ions and ibuprofen in water according to the steps in Example 4. As shown in Table 1, the total iron concentration of both the divalent and trivalent iron systems in the final effluent from the reactor is less than 0.3 mg / L, meeting the Class III water requirements of the "Groundwater Quality Standard" (GBT14848-2017), and is suitable for centralized drinking water sources and industrial and agricultural water use. The removal rate of ibuprofen exceeds 96%, indicating that this invention has a good simultaneous removal capacity for ibuprofen in groundwater.

[0071] The effectiveness of Example 4 in removing ibuprofen via ozone oxidation was compared with that of reported modified activated carbon (alkali-modified, oxidatively modified, reductively modified, metal-doped, etc.). In Example 4, 50 mg of iron-nitrogen-carbon magnetic material was used to remove 1.0 mg / L ibuprofen under 0.4 mg / L ozone conditions, with a removal rate of approximately 90% after 5 minutes of reaction. In contrast, the comparative documents showed that 25 mg of a preferred reductively modified activated carbon was used to remove 0.7 mg / L ibuprofen under 3.0 mg / L ozone conditions, with a removal rate of less than 50% after 5 minutes of reaction; and 50 mg of a preferred Mn-doped magnetic sludge-based activated carbon was used to remove 0.6 mg / L ibuprofen under 0.5 mg / L ozone conditions, with a removal rate of only 40% after 5 minutes of reaction. Increasing the ozone concentration to 3.0 mg / L resulted in an ibuprofen removal effect similar to that of this invention in the comparative documents.

[0072] Table 1. Effect of Simultaneous Removal of Iron and Ibuprofen from Groundwater in Example 4

[0073]

[0074] Example 5:

[0075] The apparatus used in this embodiment is the same as that in Embodiment 4. The method for simultaneously removing combined pollution of iron and ibuprofen-like drugs from groundwater using iron-nitrogen-carbon based magnetic materials is carried out according to the following steps:

[0076] a. Adjust the pH of the groundwater to 5.5, and pump the groundwater containing 0.2 mg / L iron ions (ferrous or ferric) and 0.2 mg / L ibuprofen into a PP cotton filter.

[0077] b. Inject the filtered groundwater from step a into an integrated iron and drug removal reactor. Turn on the agitator inside the reactor. The iron-nitrogen-carbon-based magnetic material inside the reactor adsorbs iron ions in the water, and simultaneously uses the adsorbed iron ions to complex iprofen-like drugs in the water, fixing the drug onto the surface of the material. The mass ratio of the iron-nitrogen-carbon-based magnetic material to the water volume in the reactor is 10 mg: 1 L. This stage takes 20 minutes to run.

[0078] c. Add 0.2 mg / L ozone to the reactor described in step b. Utilize the catalytic properties of the iron-nitrogen-carbon-based magnetic material within the reactor to achieve the complete decomposition of ibuprofen-like drugs and the regeneration of adsorption sites. This stage takes 10 minutes.

[0079] d. Turn on the electromagnet for 5 minutes to recover the iron-nitrogen-carbon-based magnetic material in the reactor.

[0080] e. The reactor effluent is filtered twice through a PP cotton filter before being discharged.

[0081] Table 2 shows the removal efficiency of the iron-nitrogen-carbon-based magnetic material prepared in Example 2 on iron ions and ibuprofen in water according to the steps in Example 5. As shown in Table 2, no residual iron ions were detected in the ferrous iron system in the reactor effluent, and the residual iron ion concentration in the ferric iron system was only 0.025 mg / L; the ibuprofen removal rate of both the ferrous iron system and the ferric iron system reached 97%. The above results indicate that the present invention still exhibits excellent simultaneous removal capability of iron and ibuprofen in a low-concentration iron-ibuprofen coexistence system.

[0082] Table 2. Effect of Simultaneous Removal of Iron and Ibuprofen from Groundwater in Example 5

[0083]

[0084] Example 6:

[0085] The apparatus used in this embodiment is the same as that in Embodiment 4. The method for simultaneously removing combined pollution of iron and ibuprofen-like drugs from groundwater using iron-nitrogen-carbon based magnetic materials is carried out according to the following steps:

[0086] a. Adjust the pH of the groundwater to 8.5, and pump the groundwater containing 2.0 mg / L of iron ions (ferrous or ferric) and 2.0 mg / L of profen drugs (a mixture of ibuprofen, ketoprofen, biprofen, loxoprofen, and pranoprofen) into a PP cotton filter.

[0087] b. Inject the filtered groundwater from step a into an integrated iron and drug removal reactor. Turn on the agitator inside the reactor. The iron-nitrogen-carbon-based magnetic material inside the reactor adsorbs iron ions in the water, and simultaneously uses the adsorbed iron ions to complex iprofen-like drugs in the water, fixing the drug onto the surface of the material. The mass ratio of the iron-nitrogen-carbon-based magnetic material to the water volume in the reactor is 100 mg: 1 L. This stage takes 40 minutes to run.

[0088] c. Add 0.6 mg / L ozone to the reactor described in step b. Utilize the catalytic properties of the iron-nitrogen-carbon-based magnetic material within the reactor to achieve the complete decomposition of profen-like drugs and the regeneration of adsorption sites. This stage takes 20 minutes.

[0089] d. Turn on the electromagnet for 20 minutes to recover the iron-nitrogen-carbon-based magnetic material in the reactor.

[0090] e. The reactor effluent is filtered twice through a PP cotton filter before being discharged.

[0091] Table 3 shows the removal efficiency of the iron-nitrogen-carbon-based magnetic material prepared in Example 3 on iron ions and five types of profenofibrate drugs in water according to the steps in Example 6. As shown in Table 3, the total iron concentration in both the divalent and trivalent iron systems in the reactor effluent was less than 0.3 mg / L, meeting the Class III water requirements of the Groundwater Quality Standard (GBT14848-2017). The removal rate of the five typical profenofibrate drugs all reached 96%, indicating that this invention has a good simultaneous removal capacity for multivalent iron and various profenofibrate drugs in groundwater.

[0092] Table 3. Effects of Example 6 on the simultaneous removal of iron ions and five types of ibuprofen from groundwater.

[0093]

[0094] The technical solutions disclosed and proposed in this invention can be implemented by those skilled in the art by appropriately modifying the conditions and routes, etc. Although the methods and preparation techniques of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.

Claims

1. An iron-nitrogen-carbon-based magnetic material for simultaneously removing combined pollution from groundwater containing iron and profen-like drugs, characterized in that, The preparation method is as follows: 1) Dissolve ferrous salts in a solvent to obtain an iron-containing solution with an iron concentration of 0.1–0.6 mol / L; 2) Mix aromatic carboxylic acid, 2-methylimidazole and 1-methylimidazole in a molar ratio of (2-4):1:1 and dissolve them in a solvent to obtain a ligand solution; 3) Add the iron-containing solution from step 1) dropwise into the ligand solution from step 2), and then continuously stir the mixture at 200-400 rpm for 12-24 h; 4) Centrifuge the mixture from step 3) to obtain insoluble matter. Wash the insoluble matter with methanol, wash with water and vacuum dry it in sequence. Place the insoluble matter in a zirconia ball mill jar and ball mill the sample at 400-600 rpm for 4-6 h. The mass ratio of sample:zirconia balls:water in the zirconia ball mill jar is (1-3):6:

2. 5) Place the ball-milled sample obtained in step 4) in a tube furnace and heat it in a nitrogen atmosphere at 500-800℃ for 2-6 hours to obtain a black iron-nitrogen-carbon based magnetic material.

2. The iron-nitrogen-carbon-based magnetic material for simultaneously removing combined pollution of iron and ibuprofen-like drugs from groundwater as described in claim 1, characterized in that, Step 1: The divalent ferric salt is ferrous sulfate, ferrous nitrate, ferrous chloride, or a hydrate of the above ferric salts.

3. The iron-nitrogen-carbon-based magnetic material for simultaneously removing combined pollution of iron and ibuprofen-like drugs from groundwater as described in claim 1, characterized in that, Step 2) The aromatic carboxylic acid is benzoic acid, phthalic acid, isophthalic acid, terephthalic acid or pyromellitic acid.

4. The iron-nitrogen-carbon-based magnetic material for simultaneously removing combined pollution of iron and ibuprofen-like drugs from groundwater as described in claim 1, characterized in that, The solvents used in steps 1) and 2) are methanol, water, or dimethylformamide.

5. The iron-nitrogen-carbon-based magnetic material for simultaneously removing combined pollution of iron and ibuprofen-like drugs from groundwater as described in claim 1, characterized in that, The molar ratio of the iron concentration in the iron-containing solution in step 1) to the organic ligand concentration in the ligand solution in step 2) is (1-6):

8.

6. The iron-nitrogen-carbon-based magnetic material for simultaneously removing combined pollution of iron and ibuprofen-like drugs from groundwater as described in claim 1, characterized in that, The volume ratio of the iron-containing solution in step 1) to the ligand solution in step 2) is (1-2):

2.

7. The iron-nitrogen-carbon-based magnetic material for simultaneously removing combined pollution of iron and ibuprofen-like drugs from groundwater as described in claim 1, characterized in that, The processes described in steps 1-3) are all operated under nitrogen protection or vacuum conditions.

8. A method for simultaneously removing combined pollution of iron and profen-like drugs from groundwater using the iron-nitrogen-carbon-based magnetic material of claim 1, characterized in that, Includes the following steps: a. Adjust the pH of the groundwater to 5.5-8.5, and pump the groundwater containing 0.2-2.0 mg / L iron ions and 0.2-2.0 mg / L profen-like drugs into a PP cotton filter; b. Inject the filtered groundwater from step a into an integrated iron and drug removal reactor, turn on the stirrer in the reactor, and use the iron-nitrogen-carbon-based magnetic material in the reactor to adsorb iron ions in the water. At the same time, the adsorbed iron ions complex the ibuprofen-like drugs in the water and fix the drugs on the surface of the material. The mass ratio of the iron-nitrogen-carbon-based magnetic material to the water volume in the reactor is 10-100 mg: 1L. The running time of the adsorption stage is 20-40 min. c. Add 0.2-0.6 mg / L ozone into the reactor in step b. Utilize the catalytic properties of ozone catalyzed by the iron-nitrogen-carbon-based magnetic material in the reactor to achieve the complete decomposition of ibuprofen drugs and the regeneration of adsorption sites. The running time of this ozonation stage is 10-20 min. d. Turn on the electromagnet for 5-15 minutes to recover the iron-nitrogen-carbon-based magnetic material in the reactor; e. The reactor effluent is filtered twice through a PP cotton filter before being discharged.

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