An interference-resistant method for purifying DOM-rich and high-arsenic groundwater

Abstract

This invention discloses an interference-resistant method for purifying DOM-rich, high-arsenic groundwater. The method involves adding an Fe / Co bimetallic organic framework (BOF) material and potassium persulfate solution to a high-arsenic groundwater sample rich in dissolved organic matter, maintaining stirring at room temperature, and achieving efficient simultaneous oxidation-adsorption removal of As(III). This method is unaffected by dissolved organic contaminants and common anions and cations. The method described herein, using the Fe / Co BOM coupled with peroxymonosulfate, can effectively purify complex, high-arsenic groundwater.

Description

Technical Field

[0001] The present invention relates to a highly efficient method for removing inorganic arsenic from wastewater, in particular to an interference-resistant method for purifying DOM-rich high-arsenic groundwater, belonging to the technical field of water treatment. Background Art

[0002] Arsenic (As) is one of the most common heavy metal pollutants, primarily originating from anthropogenic activities such as smelting, mining, the application of pesticides and fertilizers, and the burning of fossil fuels. Studies have shown that excessive exposure to As can lead to neurological disorders, organ damage, and anemia. In groundwater, As primarily exists as trivalent arsenic [As(III)] rather than pentavalent arsenic [As(V)] or organic arsenic. Furthermore, As(III) is more soluble and mobile in groundwater. Due to the poor affinity of As(III) for various adsorbents, conventional adsorption techniques are unable to achieve efficient removal of As(III) from high-arsenic groundwater. Synchronous oxidative adsorption techniques, derived from heterogeneous persulfate advanced oxidation processes, are attracting increasing attention for the immobilization of As(III).

[0003] However, the hydrochemistry of high-arsenic groundwater is complex, with the presence of high concentrations of dissolved organic matter (DOM) being a hallmark. The presence of DOM not only quenches sulfate and hydroxyl radicals, which effectively oxidize As(III) in the persulfate advanced oxidation process, but also competes with the oxidation product, As(V), for available adsorption sites on the adsorbent surface, thereby inhibiting the oxidation and fixation of As(III) in the process.

[0004] Therefore, the development of new heterogeneous catalysts that can resist the negative effects of DOM has become an area that urgently needs to be explored in the development of groundwater As(III) pollution removal technology. Summary of the Invention

[0005] Purpose of the invention: From the perspective of human health, in order to solve the problem of effective purification of high-arsenic groundwater, the present invention provides a method for purifying DOM-rich high-arsenic groundwater that can not only combine Fe / Co bimetallic organic framework material (Fe / Co-MOF) and peroxymonosulfate (PMS) to synchronously oxidize and adsorb As(III), but also effectively resist the negative impact of DOM.

[0006] Technical solution: In order to solve the above technical problems, the present invention provides an interference-resistant purification method for DOM-rich high-arsenic groundwater. The purification method comprises adding Fe / Co-MOF and PMS solutions to DOM-rich high-arsenic groundwater, stirring the reaction at room temperature, and filtering to complete the removal of As(III).

[0007] The stirring reaction time at room temperature is 1 min to 24 h.

[0008] Wherein, the concentration of As(III) in the water body is 0.2-2.2 mg / L.

[0009] The concentration of DOM in the water body is 0-10.16 mg / L.

[0010] The average concentration of the Fe / Co bimetallic MOF in water is 0.5 g / L.

[0011] The final concentration of the PMS solution in water is 10-100 mg / L.

[0012] The preparation method of the Fe / Co-MOF comprises the following steps: ferrous chloride tetrahydrate, cobalt nitrate hexahydrate and terephthalic acid are reacted under solvent thermal conditions to form Fe / Co-MOF.

[0013] The mass ratio of ferrous chloride tetrahydrate, cobalt nitrate hexahydrate and terephthalic acid is: (3-6): (6-3): 3.6.

[0014] The solvent in the solvent thermal reaction is a mixed solution of N,N-dimethylformamide, anhydrous methanol and ultrapure water, with a mass ratio of 10:2:1. The solvent thermal reaction conditions are: reaction at 120 degrees Celsius for 24 hours.

[0015] The step further includes centrifuging the product after the solvothermal reaction and repeatedly washing it with anhydrous ethanol and ultrapure water for 3-4 times, and drying it in a vacuum drying oven at 60-70 degrees Celsius for 12-13 hours to obtain Fe / Co-MOF.

[0016] Reaction mechanism: Different from the common oxidation process dominated by free radicals (such as sulfate radicals and hydroxyl radicals), in the present invention, the oxidation process of As(III) is dominated by non-free radicals, such as singlet oxygen ( 1 O2) dominates, compared with free radicals, 1 O₂ is difficult to quench by DOM, effectively counteracting the inhibitory effects of DOM on the oxidation process. During the As(V) adsorption process, the Fe / Co MOF adsorbs As(V) through chemical adsorption and DOM through physical adsorption. There is no competitive adsorption between DOM and As(V), effectively counteracting the inhibitory effects of DOM on the adsorption process. In summary, the present invention effectively counteracts the negative effects of DOM.

[0017] Beneficial Effects: Compared with existing technologies, the present invention offers the following significant advantages: the Fe / Co-MOF-coupled PMS can achieve efficient simultaneous oxidation and fixation of As(III). Furthermore, the Fe / Co-MOF-coupled PMS can significantly mitigate the negative effects of DOM. This method is simple to operate, highly feasible, and highly effective, with broad prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the X-ray diffraction pattern of Fe / Co-MOF prepared in Example 1.

[0019] Figure 2 This is a comparison diagram of the effects of Example 4 and Comparative Example 1.

[0020] Figure 3 It is a comparison diagram of the effects of Example 5 and Comparative Example 2.

[0021] Figure 4 This is a comparison diagram of the effects of Example 6 and Comparative Example 3.

[0022] Figure 5 This is the effect diagram of Example 7.

[0023] Figure 6 This is a comparison diagram of the effects of Example 8 and Example 9.

[0024] Figure 7 This is a comparison diagram of the effects of Example 10 and Comparative Example 4.

[0025] Figure 8 This is a comparison diagram of the effects of Example 11 and Comparative Example 5.

[0026] Figure 9 This is the fitting result diagram of Example 11.

[0027] Figure 10 This is the fitting result diagram of Comparative Example 6. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0029] Preparation of DOM-rich high-arsenic groundwater: Sodium arsenite (NaAsO2) was dissolved in ultrapure water at a concentration of 0.2 to 5.0 mg / L (including 0.2, 0.5, 1, 1.5, 2.2, and 5.0 mg / L), and the pH of the aqueous solution was adjusted to 7; humic acid was added as a model substance for DOM to the above-mentioned As(III) solution, wherein the DOM concentration was 10.16 mgC / L.

[0030] Preparation of PMS stock solution: The concentration of potassium persulfate is 10-100g / L.

[0031] Example 1 Preparation of Fe / Co-MOF-1

[0032] 4.5 mmol of ferrous chloride tetrahydrate, 4.5 mmol of cobalt nitrate hexahydrate, and 3.6 mmol of terephthalic acid were dissolved in a mixture containing 30 mL of N,N-dimethylformamide, 6 mL of methanol, and 3 mL of ultrapure water. The mixture was then stirred at room temperature for 2 hours and then transferred to a high-temperature, high-pressure reactor and heated in a 120°C electric oven for 24 hours. After cooling to room temperature, the crude product was washed three times with ethanol and then ultrapure water, respectively, and dried in a vacuum oven at 70°C to obtain Fe / Co-MOF-1.

[0033] Example 2 Preparation of Fe / Co-MOF-0.5

[0034] 3 mmol of ferrous chloride tetrahydrate, 6 mmol of cobalt nitrate hexahydrate, and 3.6 mmol of terephthalic acid were dissolved in a mixture containing 30 mL of N,N-dimethylformamide, 6 mL of methanol, and 3 mL of ultrapure water. The mixture was then stirred at room temperature for 2 hours and then transferred to a high-temperature, high-pressure reactor and heated in a 120°C electric oven for 24 hours. After cooling to room temperature, the crude product was washed three times with ethanol and three times with ultrapure water, respectively, and dried in a vacuum oven at 70°C to obtain Fe / Co-MOF-0.5.

[0035] Example 3 Preparation of Fe / Co-MOF-2

[0036] 6 mmol of ferrous chloride tetrahydrate, 3 mmol of cobalt nitrate hexahydrate, and 3.6 mmol of terephthalic acid were dissolved in a mixture containing 30 mL of N,N-dimethylformamide, 6 mL of methanol, and 3 mL of ultrapure water. The mixture was then stirred at room temperature for 2 hours and then transferred to a high-temperature, high-pressure reactor and heated in a 120°C electric oven for 24 hours. After cooling to room temperature, the crude product was washed three times with ethanol and three times with ultrapure water, respectively, and dried in a vacuum oven at 70°C to obtain Fe / Co-MOF-2.

[0037] Example 4: Purification of DOM-rich and high-arsenic groundwater by coupling Fe / Co-MOF-1 with PMS

[0038] First, 100 mL of DOM (10.16 mgC / L) and As(III) solutions were respectively measured and placed in 250 mL Erlenmeyer flasks. The As(III) concentrations were 0.2, 0.5, 1, 1.5, and 2.2 mg / L, respectively. The solutions were then placed in a constant temperature water bath shaker at 170 rpm. A precision electronic balance was used to weigh 50 mg of the Fe / Co-MOF-1 prepared in Example 1. PMS stock solutions of varying concentrations were then pipetted using a precision pipette to achieve final PMS concentrations of 10, 25, 50, and 100 mg / L, respectively. Both solutions were then added to the flasks. After 24 hours, 1 mL of the sample was pipetted and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the sample was then determined by inductively coupled plasma spectroscopy.

[0039] Example 5: Purification of DOM-rich and high-arsenic groundwater by coupling Fe / Co-MOF-0.5 with PMS

[0040] First, 100 mL of DOM (10.16 mgC / L) and As(III) solutions were measured and placed in 250 mL Erlenmeyer flasks, with As(III) concentrations of 0.2, 0.5, 1, 1.5, and 2.2 mg / L, respectively. The solutions were then placed in a constant-temperature water bath shaker at 170 rpm. A precision electronic balance was used to weigh 50 mg of the Fe / Co-MOF-0.5 prepared in Example 2. 100 μL of a 50 g / L PMS stock solution was then pipetted and added to the flasks. After 24 hours, a 1 mL sample was pipetted and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the sample was then determined by inductively coupled plasma spectroscopy.

[0041] Example 6: Purification of DOM-rich and high-arsenic groundwater by coupling Fe / Co-MOF-2 with PMS

[0042] First, 100 mL of DOM (10.16 mgC / L) and As(III) solutions were measured and placed in 250 mL Erlenmeyer flasks, with As(III) concentrations of 0.2, 0.5, 1, 1.5, and 2.2 mg / L, respectively. The solutions were then placed in a constant-temperature water bath shaker at 170 rpm. A precision electronic balance was used to weigh 50 mg of the Fe / Co-MOF-2 prepared in Example 3. 100 μL of a 50 g / L PMS stock solution was then pipetted and added to the flasks. After 24 hours, a 1 mL sample was pipetted and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the sample was then determined by inductively coupled plasma spectroscopy.

[0043] Example 7 Effect of coexisting anions and cations on the purification of DOM-rich and high-arsenic groundwater by Fe / Co-MOF-1 coupled PMS

[0044] First, 100 mL of DOM containing 10.16 mg C / L and different anions and cations (Cl - 、HCO3 - 、SO4 2- , Ca 2+ Mg 2+ ) and As(III) solutions were placed in a 250 mL conical flask, with As(III) concentrations of 0.2, 0.5, 1, 1.5, and 2.2 mg / L, respectively. The solutions were placed in a constant temperature water bath shaker at 170 rpm. 50 mg of the Fe / Co-MOF-1 prepared in Example 1 was weighed using a precision electronic balance, and 100 μL of a 50 g / L PMS stock solution was taken using a precision pipette. Both were added to the conical flask. After 24 hours, 1 mL of the sample was taken using a pipette and filtered through a 0.45 μm aqueous filter membrane. The remaining arsenic content in the sample was then determined by inductively coupled plasma spectroscopy.

[0045] Example 8 Kinetics of Fe / Co-MOF-1 coupled PMS purification of DOM-rich and high-arsenic groundwater

[0046] First, 100 mL of a solution containing 10.16 mgC / L DOM and 1.0 mg / L As(III) was placed in a 250 mL Erlenmeyer flask. The solution was then placed in a constant temperature water bath at 170 rpm. A precision electronic balance was used to weigh 50 mg of the Fe / Co-MOF-1 prepared in Example 1. 100 μL of a 50 g / L PMS stock solution was then added to the flask. Over time periods ranging from 1 to 300 minutes (1, 2, 5, 10, 20, 30, 40, 60, 90, 120, 180, 240, and 300 minutes), 1 mL of the sample was removed with a pipette and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the sample was then determined using inductively coupled plasma spectroscopy.

[0047] Example 9 Effect of quenching agent methanol or furfuryl alcohol on the purification of DOM-rich and high-arsenic groundwater by Fe / Co-MOF coupled PMS

[0048] First, 100 mL of a solution containing 10.16 mgC / L DOM, excess methanol or furfuryl alcohol, and As(III) were separately measured in a 250 mL Erlenmeyer flask, with an As(III) concentration of 1.0 mg / L. The solution was then placed in a constant-temperature water bath at 170 rpm. A precision electronic balance was used to weigh 50 mg of the Fe / Co-MOF-1 prepared in Example 1. 100 μL of a 50 g / L PMS stock solution was then pipetted and added to the flask. Within 1 minute to 3 hours, 1 mL of the sample was pipetted and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the sample was then determined using inductively coupled plasma spectroscopy.

[0049] Example 10 Detection of Singlet Oxygen in Fe / Co-MOF-1 Coupled PMS System in DOM-Rich Water

[0050] 0.5 g / L of Fe / Co-MOF-1 prepared in Example 1, 50 mg / L of PMS, and 100 mM of 2,2,6,6-tetramethylpiperidine (TEMP) were added to a 10.16 mgC / L DOM-free aqueous solution with a pH of 7. After reacting for 5 minutes, a certain amount of the reaction solution was aspirated using a capillary and detected by electron spin resonance spectrometry (EPR).

[0051] Example 11 Adsorption of As(V) in DOM-rich water by Fe / Co-MOF-1

[0052] First, 100 mL of a solution enriched with 10.16 mgC / L of DOM and As(V) was measured into a 250 mL Erlenmeyer flask. The As(V) concentrations were 5.089, 10.59, 20.72, 52.35, and 107.7 mg / L, respectively. This solution was then placed in a constant-temperature water bath at a shaking speed of 170 rpm. 50 mg of the Fe / Co-MOF-1 prepared in Example 1 was weighed using a precision electronic balance and added to the flask. After 24 hours, a 1 mL sample was pipetted and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the sample was then determined using inductively coupled plasma spectroscopy.

[0053] Comparative Example 1: Purification of DOM-free and high-arsenic groundwater by coupling Fe / Co-MOF-1 with PMS

[0054] First, 100 mL of DOM-free solutions containing As(III) concentrations of 0.2, 0.5, 1, 1.5, and 2.2 mg / L were measured and placed in a 250 mL Erlenmeyer flask. The solutions were then placed in a constant-temperature water bath shaker at 170 rpm. A precision electronic balance was used to weigh 50 mg of the Fe / Co-MOF-1 prepared in Example 1. Using a precision pipette, various PMS stock solutions were added to the flasks, achieving final PMS concentrations of 10, 25, 50, and 100 mg / L. After 24 hours, 1 mL of the samples were pipetted and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the samples was then determined using inductively coupled plasma spectroscopy.

[0055] Comparative Example 2: Purification of DOM-free and high-arsenic groundwater by coupling Fe / Co-MOF-0.5 with PMS

[0056] First, 100 mL of DOM-free solutions containing 0.2, 0.5, 1, 1.5, and 2.2 mg / L of As(III) were measured and placed in a 250 mL Erlenmeyer flask. The solutions were then placed in a constant-temperature water bath at 170 rpm. Using a precision electronic balance, 50 mg of the Fe / Co-MOF-0.5 prepared in Example 2 was weighed. Using a precision pipette, 100 μL of a 50 g / L PMS stock solution was added to the flask. After 24 hours, 1 mL of the sample was pipetted and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the sample was then determined using inductively coupled plasma spectroscopy.

[0057] Comparative Example 3: Purification of DOM-free and high-arsenic groundwater by coupling Fe / Co-MOF-2 with PMS

[0058] First, 100 mL of DOM-free solutions containing 0.2, 0.5, 1, 1.5, and 2.2 mg / L of As(III) were measured and placed in 250 mL Erlenmeyer flasks. The solutions were then placed in a constant-temperature water bath at 170 rpm. Using a precision electronic balance, 50 mg of the Fe / Co-MOF-2 prepared in Example 3 was weighed. Using a precision pipette, 100 μL of a 50 g / L PMS stock solution was added to the flasks. After 24 hours, 1 mL of the sample was pipetted and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the sample was then determined using inductively coupled plasma spectroscopy.

[0059] Comparative Example 4 Detection of singlet oxygen in Fe / Co-MOF-1 coupled PMS system in pure water

[0060] 50 mg / L PMS and 100 mM TEMP were added to a pH 7 aqueous solution without DOM or AS(III) and reacted for 5 minutes. A certain amount of the reaction solution was drawn by capillary tube and detected by EPR.

[0061] Comparative Example 5 Adsorption of As(V) in DOM-free water by Fe / Co-MOF-1

[0062] First, 100 mL of DOM-free solutions containing As(V) concentrations of 5.089, 10.59, 20.72, 52.35, and 107.7 mg / L, respectively, were measured and placed in a 250 mL Erlenmeyer flask. The solution was then placed in a constant-temperature water bath shaker at 170 rpm. 50 mg of the Fe / Co-MOF prepared in Example 1 was weighed using a precision electronic balance and added to the flask. After 24 hours, 1 mL of the sample was pipetted and filtered through a 0.45 μm aqueous filter. The remaining arsenic content in the sample was then determined using inductively coupled plasma spectroscopy.

[0063] Comparative Example 6 Adsorption of DOM in Arsenic-Free Water by Fe / Co-MOF-1

[0064] First, 100 mL of arsenic-free solutions containing humic acid concentrations of 20, 50, 100, 200, and 500 mg / L were measured and placed in a 250 mL Erlenmeyer flask. The solution was then placed in a constant-temperature water bath shaker at 170 rpm. Using a precision electronic balance, 50 mg of the Fe / Co-MOF-1 prepared in Example 1 was weighed and added to the flask. After 24 hours, 5 mL of the sample was pipetted and filtered through a 0.45 μm aqueous filter. The remaining humic acid content in the sample was then determined using a UV-visible spectrometer.

[0065] The above experimental results and analysis can be found in Figures 1 to 10 .

[0066] The results of Example 1 are shown in Figure 1 ,Depend on Figure 1 It can be seen that Fe / Co-MOF contains characteristic diffraction peaks of Fe-MOF and Co-MOF, indicating the successful synthesis of the bimetallic MOF in Example 1. The characterization diagrams of Examples 2 and 3 are similar to those of Example 1.

[0067] The experimental results of Example 4 and Comparative Example 1 are shown in Figure 2 ,Depend on Figure 2 It can be seen that the coexistence of high-concentration DOM will not significantly weaken the purification effect of high-arsenic groundwater, and the Fe / Co-MOF-1 coupled PMS process has excellent anti-interference ability.

[0068] The experimental results of Example 5 and Comparative Example 2 are shown in Figure 3 ,Depend on Figure 3 It can be seen that the coexistence of high-concentration DOM will not significantly weaken the purification effect of high-arsenic groundwater, and the Fe / Co-MOF-0.5 coupled PMS process has excellent anti-interference ability.

[0069] The experimental results of Example 6 and Comparative Example 3 are shown in Figure 4 ,Depend on Figure 4 It can be seen that the coexistence of high-concentration DOM will not significantly weaken the purification effect of high-arsenic groundwater, and the Fe / Co-MOF-2 coupled PMS process has excellent anti-interference ability.

[0070] The experimental results of Example 7 are shown in Figure 5 ,Depend on Figure 5 It can be seen that the coexistence of other common anions and cations in groundwater will not affect the purification effect of DOM-rich and high-arsenic groundwater, indicating that the Fe / Co-MOF coupled PMS process also has excellent resistance to other anions and cations.

[0071] The experimental results of Example 8 and Example 9 are shown in Figure 6 ,Depend on Figure 6 It can be seen that methanol has little effect on the water purification process, while the coexistence of excess furfuryl alcohol significantly inhibits the purification effect of high-arsenic groundwater, and singlet oxygen dominates the As(III) oxidation process.

[0072] The experimental results of Example 10 and Comparative Example 4 are shown in Figure 7 ,Depend on Figure 7 It can be seen that the coexistence of DOM can significantly promote the generation of singlet oxygen, and DOM does not inhibit the oxidation of As(III).

[0073] The experimental results of Example 11 and Comparative Example 5 are shown in Figure 8 ,Depend on Figure 8 It can be seen that the presence of DOM does not significantly inhibit the adsorption of As(V).

[0074] The experimental data fitting results of Example 11 and Comparative Example 6 are shown in Figure 9 and 10 ,Depend on Figure 9 and 10 As can be seen, the adsorption of As(V) is more consistent with the Langmuir isotherm model, where chemical adsorption dominates the adsorption process, while the adsorption of humic acid is more consistent with the Freundlich isotherm model, where physical adsorption dominates the adsorption process. Humic acid does not compete for the adsorption sites on Fe / Co-MOF that are effective for As(V) adsorption and therefore does not inhibit the adsorption of As(V).

[0075] Depend on Figure 7 、 Figure 8 、 Figure 9 and Figure 10It can be seen that DOM neither inhibits the oxidation of As(III) nor the adsorption of As(V). This is the fundamental reason why Fe / Co-MOF coupled PMS can efficiently purify DOM-rich high-arsenic groundwater.

Claims

1. A method for purifying DOM-rich high-arsenic groundwater with an anti-interference property, characterized in that: The purification method includes adding an Fe / Co bimetallic organic framework material and a peroxymonosulfate solution to DOM-rich high-arsenic groundwater, stirring the reaction at room temperature, and filtering. The oxidation process of As(III) is dominated by singlet oxygen, and DOM is bound to the Fe / Co-MOF surface through physical adsorption, without competing with As(V) for adsorption sites.

2. The method for purifying interference-resistant DOM-rich high-arsenic groundwater according to claim 1, characterized in that: The reaction time under room temperature stirring is 1 min-24 h.

3. The method for purifying interference-resistant DOM-rich high-arsenic groundwater according to claim 1, characterized in that: The concentration of DOM is 0-10.16 mg / L.

4. The method for purifying interference-resistant DOM-rich high-arsenic groundwater according to claim 1, characterized in that: The As(III) concentration in the high-arsenic groundwater is 0.2-2.2 mg / L.

5. The method for purifying interference-resistant DOM-rich high-arsenic groundwater according to claim 1, characterized in that: The final concentration of the peroxymonosulfate solution in water is 10-100 mg / L.

6. The interference-resistant purification method for DOM-rich high-arsenic groundwater according to claim 1, characterized in that: The final concentration of the Fe / Co bimetallic organic framework material in water is 0.5 g / L.

7. The interference-resistant purification method for DOM-rich high-arsenic groundwater according to claim 1, characterized in that: The preparation method of the Fe / Co-MOF comprises the following steps: ferrous chloride tetrahydrate, cobalt nitrate hexahydrate and terephthalic acid are reacted under solvent thermal conditions to form Fe / Co-MOF.

8. The interference-resistant purification method for DOM-rich high-arsenic groundwater according to claim 7, characterized in that: The mass ratio of the ferrous chloride tetrahydrate, cobalt nitrate hexahydrate and terephthalic acid is: (3-6): (6-3): 3.

6.

9. The interference-resistant purification method for DOM-rich high-arsenic groundwater according to claim 7, characterized in that: The solvent used in the solvothermal reaction is a mixed solution of N,N-dimethylformamide, anhydrous methanol and ultrapure water, with a mass ratio of 10:2:

1. The solvothermal reaction conditions are: reaction at 120 degrees Celsius for 24 hours.

10. The interference-resistant purification method for DOM-rich high-arsenic groundwater according to claim 7, characterized in that: The preparation method of the Fe / Co-MOF further includes centrifuging the product after the solvothermal reaction, repeatedly washing it with anhydrous ethanol and ultrapure water for 3-4 times, and drying it in a vacuum drying oven at 60-70 degrees Celsius for 12-13 hours to obtain Fe / Co-MOF.

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