Method for degrading micropollutants by coupling inorganic double-layer membrane with peroxymonosulfate catalytic filtration system

Abstract

The invention discloses a method for degrading micro-pollutants by coupling an inorganic double-layer membrane with a peroxymonosulfate catalytic filtration system, and belongs to the field of water body micro-pollutant treatment. The invention aims to solve the problems of low degradation efficiency and poor selectivity in degradation of various micro-pollutants in the prior art. The method comprises the following steps of: 1, mixing nickel powder and organic polymer powder, ball-milling, pressing into a membrane under certain pressure, calcining in a tubular furnace to obtain a nickel-based membrane, preparing a double-layer membrane by using plastic powder as a solid carbon source through a chemical vapor deposition method, cleaning, drying, and calcining in a mixed atmosphere of argon and hydrogen to obtain a carbon-nickel double-layer membrane; and 2, by taking a carbon-nickel double-layer membrane as a filtering membrane, adding peroxymonosulfate to degrade a solution containing micropollutants in a cross-flow filtering mode. The preparation process of the inorganic double-layer membrane is simple, the unique structure of the inorganic double-layer membrane can effectively activate singlet oxygen oxidation and direct electron transfer paths, and efficient and selective degradation of multi-component pollutants is achieved.

Description

Technical Field

[0001] This invention belongs to the field of water micro-pollutant treatment, specifically relating to a method for degrading micro-pollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system. Background Technology

[0002] Waterborne micropollutants are diverse and complex in composition (such as antibiotics and endocrine disruptors), making them difficult to remove effectively using conventional water treatment processes. Oxytetracycline, a tetracycline antibiotic, poses a serious threat to food safety and human health due to its residues. Phenolic endocrine disruptors, due to their high toxicity, high biological resistance, and stable structure, can persist widely and permanently in the ecological environment. Therefore, controlling the levels of antibiotics and phenolic substances within reasonable ranges is crucial for ecological environment and public health and safety.

[0003] To address this issue, catalytic membrane coupled with persulfate oxidation technology can effectively remove pollutants, enhance mass transfer, and minimize secondary pollution. Most reported catalytic membrane filtration systems to date rely on free radical pathways (such as... • OH, SO4 •- While catalytic membranes decompose pollutants, they suffer from poor selectivity, susceptibility to background interference, and high operating costs. Non-radical pathways, due to their enhanced selectivity and stability, have emerged as promising alternatives, primarily through singlet oxygen oxidation and direct electron transfer. Furthermore, existing catalytic membranes are mainly prepared using carbon-based materials and metal oxide materials. Carbon-based materials, such as carbon nanotubes (CNTs), graphene oxide, and biochar, exhibit excellent catalytic performance for permonosulfate (PMS) activation and can oxidize organic pollutants via a direct electron transfer pathway. Metal oxide materials, such as Fe3O4, Co3O4, NiO, and MnO2, can effectively promote the singlet oxygen oxidation pathway. However, existing catalytic membranes are mainly designed using single catalytic materials, limiting their ability to degrade pollutants through a single pathway and failing to achieve efficient removal of multi-component pollutants in complex water bodies. Summary of the Invention

[0004] The purpose of this invention is to address the problems of low degradation efficiency and poor selectivity in existing technologies for degrading various micropollutants. Therefore, this invention aims to provide a carbon-nickel bilayer catalytic membrane that can simultaneously and sequentially utilize singlet oxygen oxidation and direct electron transfer mechanisms to degrade pollutants. This invention also aims to provide a method for preparing the carbon-nickel bilayer catalytic membrane. Furthermore, this invention aims to provide a method for degrading various micropollutants by coupling the carbon-nickel bilayer membrane with a sulfate catalytic filtration system.

[0005] A method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system is specifically carried out according to the following steps:

[0006] I. Preparation of bilayer membrane:

[0007] ① After mixing nickel powder and organic polymer powder, the mixture is ball-milled for a period of time to obtain a mixed powder;

[0008] ② Press the mixed powder into a film, and then heat it to 550℃~600℃ and hold it under a nitrogen atmosphere, then heat it to 800℃~900℃ and hold it, and finally cool it to room temperature to obtain a nickel substrate film.

[0009] ③ The nickel substrate film is ultrasonically cleaned and dried to obtain the treated nickel substrate film; the treated nickel substrate film is placed in a chemical vapor deposition apparatus. Under a mixed atmosphere of argon and hydrogen, and with plastic powder as a solid carbon source, the chemical vapor deposition apparatus is first heated to 500℃~550℃ and held, then heated to 600℃~800℃ and held, and finally cooled to room temperature to obtain a carbon-nickel bilayer film.

[0010] II. Degradation of micro-pollutants:

[0011] Using a carbon-nickel bilayer membrane as the filtration membrane, in cross-flow filtration mode, a solution containing micro-contaminants is filtered at 100 L / m³. -2 h -1

[0012] ~200 L m -2 h -1 The solution is filtered at a certain flow rate, and persulfate is added to the solution containing micro-contaminants to activate the reaction, resulting in a solution with micro-contaminants removed.

[0013] The beneficial effects of this invention are:

[0014] I. The bilayer catalytic membrane in this invention can achieve the degradation of pollutants via various non-radical pathways. During filtration, it gradually activates the direct electron transfer mechanism in the carbon nanotube layer and the nickel layer. 1 The O2 oxidation mechanism achieves efficient removal of multi-component micropollutants in complex water bodies, with degradation rates of 93.7% and 100% for oxytetracycline and phenol, respectively.

[0015] Second, the preparation process and equipment of the bilayer catalytic membrane described in this invention are simple and can be mass-produced. The inorganic bilayer membrane preparation process is simple, and its unique structure can effectively activate singlet oxygen oxidation and direct electron transfer pathways, achieving efficient and selective degradation of multi-component micro-pollutants. It shows great application potential in the control of micro-pollutants in the field of water treatment. Attached Figure Description

[0016] Figure 1 The images show cross-sectional electron microscope (EM) images and magnified EEM images of the carbon-nickel bilayer film prepared in step one of Example 1.

[0017] Figure 2The degradation curves are for the catalytic filtration system in step two of Example 1 when the micro-pollutants are oxytetracycline and phenol.

[0018] Figure 3 In the carbon-nickel bilayer film prepared for Example 1, the Ni layer and CNT layer are... 1 EPR spectrum in the presence of O2 scavenger. In the figure, Ni is the nickel layer in the carbon-nickel bilayer film, CNT is the carbon nanotube layer in the carbon-nickel bilayer film, and PMS is potassium persulfate.

[0019] Figure 4 The figures show the current-time characterization results of the CNT layer in the carbon-nickel bilayer film prepared in Example 1 when PMS and micro-pollutants were added sequentially. (a) Phenol, (b) oxytetracycline. Detailed Implementation

[0020] Specific Implementation Method 1: This implementation method describes a method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system, which is specifically completed according to the following steps:

[0021] I. Preparation of bilayer membrane:

[0022] ① After mixing nickel powder and organic polymer powder, the mixture is ball-milled for a period of time to obtain a mixed powder;

[0023] ② Press the mixed powder into a film, and then heat it to 550℃~600℃ and hold it under a nitrogen atmosphere, then heat it to 800℃~900℃ and hold it, and finally cool it to room temperature to obtain a nickel substrate film.

[0024] ③ The nickel substrate film is ultrasonically cleaned and dried to obtain the treated nickel substrate film; the treated nickel substrate film is placed in a chemical vapor deposition apparatus. Under a mixed atmosphere of argon and hydrogen, and with plastic powder as a solid carbon source, the chemical vapor deposition apparatus is first heated to 500℃~550℃ and held, then heated to 600℃~800℃ and held, and finally cooled to room temperature to obtain a carbon-nickel bilayer film.

[0025] II. Degradation of micro-pollutants:

[0026] Using a carbon-nickel bilayer membrane as the filtration membrane, in cross-flow filtration mode, a solution containing micro-contaminants is filtered at 100 L / m³. -2 h -1

[0027] ~200 L m -2 h -1 The solution is filtered at a certain flow rate, and persulfate is added to the solution containing micro-contaminants to activate the reaction, resulting in a solution with micro-contaminants removed.

[0028] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the mass ratio of nickel powder to organic polymer powder in step one ① is (3~5):1. The other steps are the same as in Specific Implementation Method One.

[0029] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the organic polymer powder mentioned in step one ① is soluble starch, polyethersulfone powder, or polymethyl methacrylate powder. The other steps are the same as in Specific Implementation Method One or Two.

[0030] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the ball milling speed in step one ① is 300 rpm to 400 rpm, and the ball milling time is 18 h to 24 h; the particle size of the nickel powder in step one ① is 0.2 μm to 5 μm. Other steps are the same as in Specific Implementation Methods One to Three.

[0031] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the heating rate in step one ② is 3 ℃ / min to 6 ℃ / min; the nitrogen flow rate in step one ② is 0.1 L / min. -1 ~0.3 Lmin -1 The other steps are the same as those in implementation methods one through four.

[0032] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the heat preservation time in step one ② is 1 h to 2 h; and the mixed powder is pressed into a film under a pressure of 20 MPa in step one ②. Other steps are the same as in Specific Implementation Methods One to Five.

[0033] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One through Six in that: in step one ③, the nickel substrate film is successively immersed in acetone and anhydrous ethanol for ultrasonic cleaning for 10 min to 30 min respectively, and then dried at 80℃ to 100℃ for 12 h to 18 h; in step one ③, the volume ratio of argon to hydrogen in the mixed atmosphere is (1~3):1, and the argon flow rate is 0.02 L / min. -1 ~0.05 L min -1 The plastic powder mentioned in step 1③ is polyethylene powder or polypropylene powder. The other steps are the same as in specific embodiments one through six.

[0034] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in the following ways: the heat preservation time in step 1.③ is 10 min to 60 min; the heating rate in step 1.③ is 3 ℃ / min to 6 ℃ / min; the upper layer of the carbon-nickel bilayer film in step 1.③ is a carbon nanotube layer, and the lower layer is a nickel layer. Other steps are the same as in Specific Implementation Methods One to Seven.

[0035] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: the persulfate mentioned in step two is potassium persulfate; the concentration of the persulfate added in step two is 0.1 mmol / L to 0.3 mmol / L. The other steps are the same as in Specific Implementation Methods One to Eight.

[0036] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: the micro-contaminants mentioned in step two are oxytetracycline and / or phenol; the concentration of the micro-contaminants in the solution containing the micro-contaminants mentioned in step two is 20 μmol / L to 200 μmol / L. The other steps are the same as in Specific Implementation Methods One to Nine.

[0037] The beneficial effects of the present invention are verified using the following embodiments:

[0038] Example 1: A method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system, specifically completed according to the following steps:

[0039] I. Preparation of bilayer membrane:

[0040] ① Preparation of nickel substrate film using the pressing and sintering method:

[0041] Nickel powder and organic polymer powder are mixed and ball-milled for a period of time to obtain a mixed powder;

[0042] The organic polymer powder mentioned in step 1① is soluble starch;

[0043] The mass ratio of nickel powder to organic polymer powder mentioned in step 1① is 4:1;

[0044] The ball milling speed mentioned in step 1① is 350 rpm, and the ball milling time is 20 h;

[0045] The nickel powder mentioned in step 1① has a particle size of 1 μm;

[0046] ② The mixed powder was pressed into a film under a pressure of 20 MPa, and then heated to 600℃ and held for 1 h under a nitrogen atmosphere, then heated to 850℃ and held for 2 h, and finally cooled to room temperature to obtain a nickel substrate film.

[0047] The heating rate described in step 1② is 5 °C / min;

[0048] In step 1, ②, the nitrogen flow rate is 0.1 L / min. -1 ;

[0049] ③ Preparation of carbon-nickel bilayer films by chemical vapor deposition:

[0050] The nickel substrate film was ultrasonically cleaned and dried to obtain the treated nickel substrate film. The treated nickel substrate film was placed in a chemical vapor deposition apparatus. Under a mixed atmosphere of argon and hydrogen, and with plastic powder as a solid carbon source, the chemical vapor deposition apparatus was first heated to 500℃ and held for 30 min, then heated to 750℃ and held for 20 min, and finally cooled to room temperature to obtain a carbon-nickel bilayer film.

[0051] The plastic powder mentioned in step 1③ is polyethylene powder;

[0052] In step 1③, the nickel substrate membrane was immersed in acetone and anhydrous ethanol for ultrasonic cleaning for 15 min each, and then dried at 80℃ for 12 h.

[0053] In step 1, ③, the volume ratio of argon to hydrogen in the mixed atmosphere is 3:1; the argon flow rate is 0.03 L / min. -1 ;

[0054] The heating rate described in step 1③ is 3 °C / min;

[0055] The carbon-nickel bilayer film described in step 1③ has a carbon nanotube layer (CNT) on the upper layer and a nickel layer (Ni) on the lower layer.

[0056] II. Degradation of micro-pollutants:

[0057] Using a carbon-nickel bilayer membrane as the filtration membrane, in cross-flow filtration mode, a solution containing micro-contaminants is filtered at 150 L / m³. -2 h -1 The flow rate is filtered, and persulfate is added to the solution containing micro-contaminants to activate the reaction, resulting in a solution (filtrate) with micro-contaminants removed.

[0058] The persulfate mentioned in step two is potassium persulfate, and the concentration is 0.2 mmol / L;

[0059] The micro-pollutants mentioned in step two are oxytetracycline and phenol;

[0060] In step two, the concentration of oxytetracycline in the solution containing micro-contaminants is 20 μmol / L, and the concentration of phenol is 20 μmol / L.

[0061] Figure 1 The images show cross-sectional electron microscope (EM) images and magnified EEM images of the carbon-nickel bilayer film prepared in step one of Example 1.

[0062] like Figure 1 As shown, the cross-sectional SEM image of the carbon-nickel bilayer film prepared in step one of Example 1 shows that CNTs are densely and uniformly distributed on the Ni-based film, indicating that CNTs were successfully catalyzed and grown on Ni particles. The dashed lines in the figure depict the CNT growth region. Furthermore, magnified SEM images of the carbon and nickel layers show the elongated tubular structure of the CNTs and the irregularly shaped large-particle structure of the Ni.

[0063] Figure 2 The degradation curves are for the catalytic filtration system in step two of Example 1 when the micro-pollutants are oxytetracycline and phenol.

[0064] from Figure 2 It can be seen that: In Example 1, the carbon-nickel bilayer membrane coupled with PMS (potassium persulfate) catalytic filtration system was used to treat the combined pollution of oxytetracycline and phenol. The results showed that after 12 hours of stable operation, the carbon-nickel bilayer membrane achieved degradation rates of 93.7% and 100% for oxytetracycline and phenol, respectively. Figure 2 In this context, C0 represents the concentration of contaminants in the feed liquid, and C represents the concentration of contaminants in the filtrate.

[0065] Figure 3 In the carbon-nickel bilayer film prepared for Example 1, the Ni layer and CNT layer are... 1 EPR spectrum in the presence of O2 scavenger. In the figure, Ni is the nickel layer in the carbon-nickel bilayer film, CNT is the carbon nanotube layer in the carbon-nickel bilayer film, and PMS is potassium persulfate.

[0066] The presence of reactive oxygen species was verified by electron paramagnetic resonance (EPR) detection; TEMP was used as... 1 O2 spin trapping agent, analyzed by detecting characteristic peak signals in the system 1 The presence of O2; such as... Figure 3 As shown, when the catalyst (CNT or Ni) is present alone, almost no peak signal is detected. A distinct triplet spectral signal (1:1:1) is observed in the standalone PMS oxidation system, which, based on the hyperfine splitting constant, is a typical triplet peak of TEMPO, indicating that the Ni layer produced [a specific catalyst] during its catalytic oxidation. 1 O2.

[0067] Figure 4 The figures show the current-time characterization results of the CNT layer in the carbon-nickel bilayer membrane prepared in Example 1 when PMS and micropollutants were added sequentially. (a) shows phenol, and (b) shows oxytetracycline. The current-time curves were recorded using chronoamperometry to monitor the electron transfer process during the CNT / PMS catalytic oxidation and degradation of phenol or oxytetracycline. Figure 4 As shown, the current in both systems increased significantly after the addition of PMS, which is attributed to the instantaneous electron transfer between the working electrode and PMS. Subsequently, the current signal decreased immediately after the addition of phenol or oxytetracycline and then gradually stabilized, indicating that direct electron transfer occurred during the catalytic oxidation of the CNT layer.

[0068] Example 2: The difference between this example and Example 1 is that the organic polymer powder mentioned in step 1① is polyethersulfone powder; the plastic powder mentioned in step 1③ is polypropylene powder; the other steps are the same as in Example 1, but the parameters can be changed.

Claims

1. A method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system, characterized in that... The preparation method is specifically carried out according to the following steps: I. Preparation of bilayer membrane: ① After mixing nickel powder and organic polymer powder, the mixture is ball-milled for a period of time to obtain a mixed powder; ② Press the mixed powder into a film, and then heat it to 550℃~600℃ and hold it under a nitrogen atmosphere, then heat it to 800℃~900℃ and hold it, and finally cool it to room temperature to obtain a nickel substrate film. ③ The nickel substrate film is ultrasonically cleaned and dried to obtain the treated nickel substrate film; the treated nickel substrate film is placed in a chemical vapor deposition apparatus. Under a mixed atmosphere of argon and hydrogen, and with plastic powder as a solid carbon source, the chemical vapor deposition apparatus is first heated to 500℃~550℃ and held, then heated to 600℃~800℃ and held, and finally cooled to room temperature to obtain a carbon-nickel bilayer film. II. Degradation of micro-pollutants: Using a carbon-nickel bilayer membrane as the filtration membrane, in cross-flow filtration mode, a solution containing micro-contaminants is filtered at 100 L / m³. -2 h -1 ~200 L m -2 h -1 The solution is filtered at a certain flow rate, and persulfate is added to the solution containing micro-contaminants to activate the reaction, resulting in a solution with micro-contaminants removed.

2. The method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system according to claim 1, characterized in that... The mass ratio of nickel powder to organic polymer powder mentioned in step 1① is (3~5):

1.

3. The method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system according to claim 1, characterized in that... The organic polymer powder mentioned in step 1① is soluble starch, polyethersulfone powder, or polymethyl methacrylate powder.

4. The method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system according to claim 1, characterized in that... The ball milling speed in step 1① is 300 rpm to 400 rpm, and the ball milling time is 18 h to 24 h; the particle size of the nickel powder in step 1① is 0.2 μm to 5 μm.

5. The method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system according to claim 1, characterized in that... The heating rate described in step 1② is 3 ℃ / min~6 ℃ / min; the nitrogen flow rate in step 1② is 0.1 L / min. -1 ~0.3 L min -1 .

6. The method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system according to claim 1, characterized in that... The heat preservation time mentioned in step 1② is 1 h to 2 h; in step 1②, the mixed powder is pressed into a film under a pressure of 20 MPa.

7. The method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system according to claim 1, characterized in that... In step 1, the nickel substrate film was successively immersed in acetone and anhydrous ethanol for ultrasonic cleaning for 10-30 minutes each, and then dried at 80-100℃ for 12-18 hours. In the mixed atmosphere of argon and hydrogen mentioned in step 1, the volume ratio of argon to hydrogen was (1-3):1, and the argon flow rate was 0.02 L / min. -1 ~0.05 L min -1 The plastic powder mentioned in step 1③ is polyethylene powder or polypropylene powder.

8. The method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system according to claim 1, characterized in that... The heat preservation time mentioned in step 1③ is 10 min to 60 min; the heating rate mentioned in step 1③ is 3 ℃ / min to 6 ℃ / min; the upper layer of the carbon-nickel bilayer film mentioned in step 1③ is a carbon nanotube layer and the lower layer is a nickel layer.

9. The method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system according to claim 1, characterized in that... The persulfate mentioned in step two is potassium persulfate; the concentration of the persulfate mentioned in step two is 0.1 mmol / L to 0.3 mmol / L.

10. The method for degrading micropollutants using an inorganic double-layer membrane coupled with a sulfate catalytic filtration system according to claim 1, characterized in that... The micro-contaminants mentioned in step two are oxytetracycline and / or phenol; the concentration of micro-contaminants in the solution containing micro-contaminants mentioned in step two is 20 μmol / L to 200 μmol / L.

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