Electrically controlled enrichment catalytic membranes, their preparation methods, and their applications in water treatment

Abstract

This invention discloses an electrically controlled enrichment catalytic membrane, its preparation method, and its application in water treatment, belonging to the field of environmental organic pollution remediation technology. The electrically controlled enrichment catalytic membrane comprises a substrate layer and a copolymer coating layer with reversible electro-oxidation-reduction properties. The substrate layer is a titanium suboxide conductive ceramic membrane with a pore size of less than 1 micrometer, and the copolymer coating layer is an organic blend polymer TMA containing nitro radical functional groups. x -co-TMPMA (1‑x) Where x% represents the degree of oxidation. This invention also provides an application of the above-mentioned electrically controlled enrichment catalytic membrane in water treatment for the removal of organic pollutants. The electrically controlled enrichment catalytic membrane is used as a filter membrane in an electrochemical water treatment device. Two filter membranes are connected to the two poles of an AC power system, with the positive and negative poles reversing during a cycle. The polluted solution is controlled to flow sequentially through the two filter membranes. By adjusting the positive and negative bias parameters on the filter membranes, hydrophobic organic pollutants in the polluted solution are adsorbed and oxidized for removal. This method is energy-saving, environmentally friendly, and easy to operate.

Description

Technical Field

[0001] This invention relates to the field of environmental organic pollution remediation technology, and in particular to electrically controlled enrichment catalytic membranes, their preparation methods, and their applications in water treatment. Background Technology

[0002] Electrocatalytic membranes possess advantages such as green energy saving, reaction confinement, quantitative tunability, and enhanced mass transfer, making them ideal candidates for advanced treatment. In particular, the catalytic degradation of pollutants within the pores is influenced by the nano-confinement effect, resulting in selectivity for oxidation products. However, studies have also shown that excessively small spaces (e.g., less than 0.4 nm) can potentially become barriers to the entry of target pollutant molecules, which is expected to inevitably have a significant adverse impact on the permeability and catalytic performance of the catalytic membrane. Given that spatial confinement can significantly improve reaction kinetics and efficiency, it is necessary to explore the differences in the interaction between pollutant molecules and the electric field. Further exploration of the coupling between micro / nano reaction spaces and electrical energy through reactor design and systems engineering can contribute to improving treatment performance.

[0003] For heterogeneous systems, oxide species are generated at the catalyst interface, and their effective range is often limited to the near-surface. Therefore, selective enrichment and oxidation of micro-pollutants at the catalytic interface can be achieved by controlling the adsorption process of pollutants. Regarding selective electrochemical separation membranes, the utility model patent with application number CN202022274054.0 focuses on metal or non-metal ions, achieving selective separation and removal through mechanisms such as redox reactions and acid-base interactions. However, most organic compounds do not undergo valence state changes, making the aforementioned selective mechanisms inapplicable. In the area of ​​selective separation membranes, besides well-established theoretical research on metal or salt ions, the Chinese invention patent with application number 202111668803.0 constructs a catalytic membrane suitable for separating and removing target pollutants from NOM, but the selective layer of this membrane is non-conductive, making it unsuitable for electrocatalytic membrane systems. Regarding selective separation electrochemical technology, the Chinese invention patent with application number 202111668803.0 achieves selective separation and removal through mechanisms such as electrostatics and hydrophilic-hydrophobic interactions. However, the application of the corresponding mechanisms to membrane research must take into account a series of problems caused by membrane fouling, such as excessive consumption of oxide species, locally amplified electric fields, micro- and nano-scale turbulence, and concentration polarization.

[0004] In summary, existing wastewater treatment technologies face limitations in practical application due to issues such as electrochemical activity, the universality of organic pollutants, and the need for long-term operation and ease of use. Therefore, there is an urgent need for a catalytic membrane capable of removing various organic pollutants in the field of electrochemical water treatment. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned technical problems and to provide an electrically controlled enrichment catalytic membrane, its preparation method, and its application. The electrically controlled enrichment catalytic membrane provided by this invention achieves selective adsorption-oxidation of target pollutants under coexisting pollution conditions. It can selectively remove coexisting pollutants through voltage regulation, and is energy-saving, environmentally friendly, and easy to operate.

[0006] To achieve the above-mentioned objectives, the specific technical solution proposed by this invention is as follows:

[0007] In a first aspect, the present invention provides an electrically controlled enrichment catalytic membrane. The electrically controlled enrichment catalytic membrane comprises a substrate layer and a copolymer coating layer having reversible electro-oxidation-reduction properties. The substrate layer is a sub-titanium oxide conductive ceramic membrane with a pore size of less than 1 micrometer. The copolymer coating layer is made of TMA, an organic blend polymer containing nitro radical functional groups. x -co-TMPMA (1-x) , 0 < x < 100, where x% represents the degree of oxidation.

[0008] Preferably, the value of x is in the range of 18 ≤ x ≤ 84, and the copolymer TMA x -co-TMPMA (1-x) In this process, the degree of oxidation ranges from 18% to 84%.

[0009] Secondly, the present invention provides a method for preparing the electrically controlled enrichment catalytic membrane described in the first aspect, the specific preparation method being as follows:

[0010] S1: 2-Methyl-2-acrylate-2,2,6,6-tetramethyl-4-piperidinyl ester was dissolved in an N,N-dimethylformamide solution purged with nitrogen to remove oxygen. Then, an azobisisobutyronitrile solution was added under oxygen-free conditions to initiate a polymerization reaction, yielding a polymer solution. The polymer solution was added to a 20–80 wt.% methanol solution until a first precipitate appeared. The first precipitate was then filtered and lyophilized to obtain the polymer PTMPMA.

[0011] S2: Dissolve the polymer PTMPMA prepared in S1 in a tetrahydrofuran solution, wherein the concentration of polymer PTMPMA is 1-3 g / mL. After cooling, add it to the oxidant and mix evenly to obtain a mixed solution containing part of the oxidized polymer PTMPMA. The oxidant is a tetrahydrofuran solution of m-chloroperoxybenzoic acid.

[0012] A mixed solution containing partially oxidized polymer PTMPMA was added to a sodium hydroxide solution until a second precipitate appeared. The second precipitate was then separated, thoroughly washed, and lyophilized to obtain copolymers TMA of different oxidation degrees. x -co-TMPMA (1-x) .

[0013] S3: The copolymer TMA obtained in S2 x -co-TMPMA (1-x) Carbon nanotubes were dissolved in N,N-dimethylformamide solution at a mass ratio of (1-4):(4-1) to obtain a precursor solution. The precursor solution was then repeatedly spin-coated onto the upper surface of the substrate membrane as a copolymer coating layer to obtain an electrically controlled enriched catalytic membrane.

[0014] Preferably, the concentration of 2-methyl-2-acrylate-2,2,6,6-tetramethyl-4-piperidinyl ester dissolved in N,N-dimethylformamide solution in S1 is 40–50 mmol. The concentration of azobisisobutyronitrile in the polymer solution is 2–4 g / L.

[0015] Preferably, in the above-mentioned S2, the mass ratio of PTMPMA to m-chloroperoxybenzoic acid in the mixed solution containing partially oxidized PTMPMA is 10:(0.174~0.995). The concentration of sodium hydroxide solution in S2 is 0.4~0.6M.

[0016] Preferably, the second precipitate in S2 is thoroughly washed as follows: the second precipitate is dissolved in tetrahydrofuran solution and washed, and then thoroughly washed with pure methanol, 20 wt.% methanol and deionized water in sequence to remove the tetrahydrofuran solution.

[0017] Preferably, the volume of the precursor solution spin-coated in S3 is 0.2 to 2 mL.

[0018] Preferably, the substrate film is a sub-titanium oxide conductive ceramic film with a diameter of 0.5 to 5 cm and a thickness of 0.2 to 3 mm.

[0019] Preferably, the above-mentioned spin coating process uses a spin coater, and spin coating is performed at a speed of 30 r / min for 5 to 30 seconds, followed by a speed of 600 r / min for 30 to 90 seconds.

[0020] Thirdly, the present invention provides an application of the electrically controlled enrichment catalytic membrane described in the first aspect in water treatment. Two such electrically controlled enrichment catalytic membranes are spaced apart as filter membranes in an electrochemical water treatment device. The two filter membranes are respectively connected to the positive and negative electrodes of an AC power system, and the positive and negative electrodes reverse direction during a cycle. The polluted solution is controlled to flow sequentially through the two filter membranes. By adjusting the positive and negative bias parameters on the filter membranes, hydrophobic organic pollutants in the polluted solution are adsorbed and oxidized for removal.

[0021] Preferably, the hydrophobic organic pollutant is one or more of phenol, sulfamethoxazole, or carbamazepine.

[0022] Preferably, the difference between the positive bias voltage and the negative bias voltage is in the range of 1.2 to 3.6V.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The present invention provides an electro-manipulated enrichment catalytic membrane with a copolymer coating layer on the membrane surface that has reversible electro-oxidation and reduction properties, which can be applied to an electrocatalytic membrane system. The adsorption-oxidation processes are realized when the membrane electrode gains or loses electrons, thereby enabling efficient removal of hydrophobic organic pollutants.

[0025] (2) The electro-controlled enrichment catalytic membrane provided by this invention, compared with traditional catalysts which are usually only applicable to a class of organic compounds with very similar redox potentials and chemical structures, allows the membrane provided by this invention to remove different types of hydrophobic organic pollutants by adjusting the voltage. In this embodiment, the membrane containing the copolymer coating layer adsorbed 1.31 to 2.13 times the amount of the three organic pollutants compared to the comparative example. Therefore, the electro-controlled enrichment catalytic membrane, through voltage regulation, has great application potential for the selective removal of organic pollutants. Attached Figure Description

[0026] Figure 1 The present invention provides a method for preparing an electrically controlled enrichment catalytic membrane, wherein a is a flowchart of the copolymer coating material preparation process; b is a schematic diagram of the copolymer coating spin coating.

[0027] Figure 2 The images shown are scanning electron microscope (SEM) images of the electrically controlled enriched catalytic membrane prepared in Example 2, where a is a scanning electron microscope image of the surface of the electrically controlled enriched catalytic membrane, and b is a scanning electron microscope image of the carbon nanotube coating on the surface of the electrically controlled enriched catalytic membrane.

[0028] Figure 3 The image shows the porosity results of the electrically manipulated enriched catalytic membrane prepared in Example 2, determined by mercury pressure measurement.

[0029] Figure 4 The images show the EPR results of the electro-manipulated enriched catalytic membrane copolymer coatings prepared in Examples 1-3 and the comparative examples.

[0030] Figure 5 The image shows the CV curve of the copolymer coating of the electrically manipulated enriched catalytic membrane prepared in Example 2.

[0031] Figure 6 To evaluate the (a) removal performance and (b) separation coefficient of the membrane system for coexisting pollutants under different alternating currents;

[0032] Figure 7 To determine the (a) current utilization efficiency and (b) energy consumption of the membrane system for coexisting pollutants when different alternating currents are applied;

[0033] Figure 8 The graph shows the removal rate of organic pollutants by the electrically controlled enrichment catalytic membranes prepared in Example 2 and the comparative example as electrodes in an electrochemical water treatment device.

[0034] Figure 9 This is a schematic diagram of the electrically controlled enrichment catalytic membrane prepared in Example 2 applied to an electrochemical water treatment device. Detailed Implementation

[0035] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in the various embodiments of the present invention can be combined accordingly without mutual conflict.

[0036] To further demonstrate the performance of the electro-manipulated enrichment catalytic membrane of the present invention, the present invention further illustrates its function and effect through examples.

[0037] Example 1

[0038] This embodiment prepared an electrically controlled enrichment catalytic membrane containing a copolymer coating with an oxidation degree of 18%. The specific steps are described below:

[0039] (1) Synthetic polymer PTMPMA

[0040] Under heating conditions of 30–40 °C, 10 g of 2-methyl-2-acrylate-2,2,6,6-tetramethyl-4-piperidinyl ester (TMPMA) was fully dissolved in 25 mL of N,N-dimethylformamide (DMF) after nitrogen purging to remove oxygen, resulting in a TMPMA concentration of 45.5 mmol. Subsequently, under anaerobic conditions (continuous nitrogen purging and rotor stirring), azobisisobutyronitrile (AIBN) solution was slowly added to the above solution in small, repeated additions to initiate a polymerization reaction. The polymerization reaction was carried out at 60 °C for 16 h to obtain a polymer solution. The concentration of AIBN in the polymer solution was 3 g / L.

[0041] The polymer solution was slowly added to 2000 mL of 20% (w / w) methanol solution using a syringe until the first precipitate appeared. The first precipitate was then filtered and freeze-dried to obtain the white polymer PTMPMA.

[0042] (2) Partial oxidation of polymer PTMPMA

[0043] 0.174 g of m-chloroperoxybenzoic acid (mCPBA) was dissolved in 3.75 mL of THF and stirred for 1 h to obtain an orange-yellow oxidant. 10 g of the polymer PTMPMA obtained in step (1) was dissolved in 5 mL of tetrahydrofuran (THF) and cooled in an ice bath. The solution was then added to the above oxidant and mixed thoroughly to obtain a mixed solution containing partially oxidized polymer PTMPMA, wherein the mass ratio of polymer PTMPMA to m-chloroperoxybenzoic acid was 10:0.174.

[0044] The solution containing the partially oxidized polymer PTMPMA was slowly added dropwise to 50 mL of 0.5 M sodium hydroxide solution (NaOH) until a second precipitate appeared. The second precipitate was filtered and then dissolved again in 7.5 mL of THF to thoroughly wash away the oxidizing agent m-chloroperoxybenzoic acid (mCPBA). Then, it was thoroughly washed with 125 mL of pure methanol, 20% (w / w) methanol, and deionized water to remove THF. The washed precipitate was vacuum filtered, lyophilized, and the oxidation degree was determined using a UV spectrophotometer. A polymer with an oxidation degree of 18% was obtained, denoted as TMA. 18 -co-TMPMA 82 .

[0045] (3) Preparation of electrically controlled enrichment catalytic membrane

[0046] 5 mg of carbon nanotubes (CNTs) and 5 mg of TMA prepared in step (2) 18 -co-TMPMA 82 The powder was dissolved in 1 mL of DMF and sonicated in an ice bath for 1 h to obtain a precursor solution. The 1 mL precursor solution was then repeatedly spin-coated onto the surface of a 2.5 cm diameter, 1.5 mm thick titanium dioxide conductive ceramic film using a spin coater. Spin-coating was performed at 30 rpm for 10 s, followed by a high speed of 600 rpm for 60 s. After drying, an electrically controlled enriched catalytic membrane was obtained.

[0047] like Figure 1 a and Figure 1 As shown in b, the electro-manipulated enrichment catalytic membrane provided by the present invention uses a high-speed spin-coating method to coat partially oxidized TMPMA polymer (TMA). x -co-TMPMA 1-x It is prepared by coating a titanium suboxide ceramic film with a diameter of 2.5 cm and a thickness of 1.5 mm.

[0048] Example 2

[0049] This embodiment prepared an electrically controlled enrichment catalytic membrane containing a copolymer coating with an oxidation degree of 51%. The specific steps are described below:

[0050] (1) Synthetic polymer PTMPMA

[0051] Under heating conditions of 30–40 °C, 10 g of 2-methyl-2-acrylate-2,2,6,6-tetramethyl-4-piperidinyl ester (TMPMA) was fully dissolved in 25 mL of N,N-dimethylformamide (DMF) after nitrogen purging to remove oxygen, resulting in a TMPMA concentration of 45.5 mmol. Subsequently, under anaerobic conditions (continuous nitrogen purging and rotor stirring), azobisisobutyronitrile (AIBN) solution was slowly added to the above solution in small, repeated additions to initiate a polymerization reaction. The polymerization reaction was carried out at 60 °C for 16 h to obtain a polymer solution. The concentration of AIBN in the polymer solution was 3 g / L.

[0052] The polymer solution was slowly added to 2000 mL of 20% (w / w) methanol solution using a syringe until a first precipitate appeared. The first precipitate was then filtered and lyophilized to obtain a white polymer, PTMPMA. The yield of polymer PTMPMA was 81.03%.

[0053] (2) Partial oxidation of polymer PTMPMA

[0054] 0.585 g of m-chloroperoxybenzoic acid (mCPBA) was dissolved in 3.75 mL of THF and stirred for 1 h to obtain an orange-yellow oxidant. 10 g of the polymer PTMPMA obtained in step (1) was dissolved in 5 mL of tetrahydrofuran (THF) and cooled in an ice bath. The solution was then added to the above oxidant and mixed thoroughly to obtain a mixed solution containing partially oxidized polymer PTMPMA, wherein the mass ratio of polymer PTMPMA to m-chloroperoxybenzoic acid was 10:0.585.

[0055] The solution containing the partially oxidized polymer PTMPMA was slowly added dropwise to 50 mL of 0.5 M sodium hydroxide solution (NaOH) until a second precipitate appeared. The second precipitate was filtered and then dissolved again in 7.5 mL of THF to thoroughly wash away the oxidizing agent m-chloroperoxybenzoic acid (mCPBA). Then, it was thoroughly washed with 125 mL of pure methanol, 20% (w / w) methanol, and deionized water to remove THF. The washed precipitate was vacuum filtered, lyophilized, and the oxidation degree was determined using a UV spectrophotometer. A polymer with an oxidation degree of 51% was obtained, denoted as TMA. 51 -co-TMPMA 49 .

[0056] (3) Preparation of electrically controlled enrichment catalytic membrane

[0057] 5 mg of carbon nanotubes (CNTs) and 5 mg of TMA prepared in step (2) 51 -co-TMPMA49 The powder was dissolved in 1 mL of DMF and sonicated in an ice bath for 1 h to obtain a precursor solution. The 1 mL precursor solution was then repeatedly spin-coated onto the surface of a 2.5 cm diameter, 1.5 mm thick titanium dioxide conductive ceramic film using a spin coater. Spin-coating was performed at 30 rpm for 10 s, followed by a high speed of 600 rpm for 60 s. After drying, an electrically controlled enriched catalytic membrane was obtained.

[0058] Example 3

[0059] This embodiment prepared an electrically controlled enrichment catalytic membrane containing a copolymer coating with an oxidation degree of 84%. The specific steps are described below:

[0060] (1) Synthetic polymer PTMPMA

[0061] Under heating conditions of 30–40 °C, 10 g of 2-methyl-2-acrylate-2,2,6,6-tetramethyl-4-piperidinyl ester (TMPMA) was fully dissolved in 25 mL of N,N-dimethylformamide (DMF) after nitrogen purging to remove oxygen, resulting in a TMPMA concentration of 45.5 mmol. Subsequently, under anaerobic conditions (continuous nitrogen purging and rotor stirring), azobisisobutyronitrile (AIBN) solution was slowly added to the above solution in small, repeated additions to initiate a polymerization reaction. The polymerization reaction was carried out at 60 °C for 16 h to obtain a polymer solution. The concentration of AIBN in the polymer solution was 3 g / L.

[0062] The polymer solution was slowly added to 2000 mL of 20% (w / w) methanol solution using a syringe until the first precipitate appeared. The first precipitate was then filtered and freeze-dried to obtain the white polymer PTMPMA.

[0063] (2) Partial oxidation of polymer PTMPMA

[0064] 0.995 g of m-chloroperoxybenzoic acid (mCPBA) was dissolved in 3.75 mL of THF and stirred for 1 h to obtain an orange-yellow oxidant. 10 g of the polymer PTMPMA obtained in step (1) was dissolved in 5 mL of tetrahydrofuran (THF) and cooled in an ice bath. The solution was then added to the above oxidant and mixed thoroughly to obtain a mixed solution containing partially oxidized polymer PTMPMA, wherein the mass ratio of polymer PTMPMA to m-chloroperoxybenzoic acid was 10:0.995.

[0065] The solution containing the partially oxidized polymer PTMPMA was slowly added dropwise to 50 mL of 0.5 M sodium hydroxide solution (NaOH) until a second precipitate appeared. The second precipitate was filtered and then dissolved again in 7.5 mL of THF to thoroughly wash away the oxidizing agent m-chloroperoxybenzoic acid (mCPBA). Then, it was thoroughly washed with 125 mL of pure methanol, 20% (w / w) methanol, and deionized water to remove THF. The washed precipitate was vacuum filtered, lyophilized, and the oxidation degree was determined using a UV spectrophotometer. A polymer with an oxidation degree of 51% was obtained, denoted as TMA. 84 -co-TMPMA 16 .

[0066] (3) Preparation of electrically controlled enrichment catalytic membrane

[0067] 5 mg of carbon nanotubes (CNTs) and 5 mg of TMA prepared in step (2) 84 -co-TMPMA 16 The powder was dissolved in 1 mL of DMF and sonicated in an ice bath for 1 h to obtain a precursor solution. The 1 mL precursor solution was then repeatedly spin-coated onto the surface of a 2.5 cm diameter, 1.5 mm thick titanium dioxide conductive ceramic film using a spin coater. Spin-coating was performed at 30 rpm for 10 s, followed by a high speed of 600 rpm for 60 s. After drying, an electrically controlled enriched catalytic membrane was obtained.

[0068] Example 4

[0069] To evaluate the performance of the electrically controlled enrichment catalytic membrane provided by this invention, this embodiment uses the electrically controlled enrichment catalytic membrane prepared in Example 2 as the positive and negative electrode materials in an electrochemical water treatment device, such as... Figure 9 As shown. Removal experiments were conducted using phenol (Phenol), sulfamethoxazole (SMX), and carbamazepine (CBZ) as hydrophobic organic pollutants. The specific steps are as follows:

[0070] A mixed solution containing 10 mg / L each of SMX, phenol, and CBZ was added to the electrochemical water treatment equipment as the contaminant solution. Relevant information regarding the contaminant solution is shown in Table 1. The electrically controlled enrichment catalytic membrane prepared in Example 2 was used as the positive and negative electrode materials in the electrochemical water treatment equipment. The electrolyte was 100 mM sodium sulfate, and the reference electrode was Ag / AgCl. An alternating current system was used, meaning the applied voltage periodically reversed between negative and positive bias voltages, as detailed in Table 2. The difference between positive and negative bias voltages, ΔE, is calculated as follows: ΔE = [E...] +The voltages (-E-) were 1.2, 2.4, and 3.6 V, respectively. This setting was based on the theoretical values ​​of the adsorption of the three pollutants, direct electrode oxidation, and indirect free radical oxidation processes, while ensuring that no side reaction of hydrolysis to produce hydrogen occurred. The pulse period was 0.01 (s), and the difference between the positive and negative bias voltages was 1.2 V, 2.4 V, and 3.6 V, respectively. The dissolved oxygen content was measured to be 6.4–8.8 mg / L.

[0071] Table 1 Pollutant-related information

[0072]

[0073] Table 2. Theoretical oxidation reactions occurring in the catalytic membrane system under the applied AC current and for each pollutant system.

[0074]

[0075] Oxidation reactions of contaminants on electrodes: direct oxidation (DO); indirect oxidation (IDO)

[0076] The separation factor (SF) for removing organic pollutants from a contaminated solution using an electrically controlled enrichment catalytic membrane is calculated using the following formula:

[0077]

[0078] The current utilization efficiency (%) of the electrically controlled enrichment catalytic membrane for removing one mole of organic pollutant is calculated by the following formula:

[0079]

[0080] In the formula, n is the number of moles of the corresponding pollutant, F is the Faraday constant, z is the number of electrons transferred during the removal of the corresponding pollutant, and i is the current value recorded by the electrochemical workstation.

[0081] The energy consumption (EC, %) required to remove one mole of pollutant is calculated by the following formula:

[0082]

[0083] In the formula, Ewe is the working electrode potential and Ece is the counter electrode potential.

[0084] Comparative Example

[0085] This comparative example prepared an electrically controlled enrichment catalytic membrane containing a copolymer coating that had not undergone partial oxidation. The specific steps are described below:

[0086] (1) Synthetic polymer PTMPMA

[0087] Under heating conditions of 30–40 °C, 10 g of 2-methyl-2-acrylate-2,2,6,6-tetramethyl-4-piperidinyl ester (TMPMA) was fully dissolved in 25 mL of N,N-dimethylformamide (DMF) after nitrogen purging to remove oxygen, resulting in a TMPMA concentration of 45.5 mmol. Subsequently, under anaerobic conditions (continuous nitrogen purging and rotor stirring), azobisisobutyronitrile (AIBN) solution was slowly added to the above solution in small, repeated additions to initiate a polymerization reaction. The polymerization reaction was carried out at 60 °C for 16 h to obtain a polymer solution. The concentration of AIBN in the polymer solution was 3 g / L.

[0088] The polymer solution was slowly added to 2000 mL of 20% (w / w) methanol solution using a syringe until a first precipitate appeared. The first precipitate was then filtered and freeze-dried to obtain a white polymer PTMPMA, which served as a copolymer coating layer that had not undergone partial oxidation.

[0089] (2) Preparation of electrically controlled enrichment catalytic membrane

[0090] 5 mg of carbon nanotubes (CNTs) and 5 mg of the polymer PTMPMA powder prepared in step (1) were dissolved in 1 mL of LDM and sonicated in an ice bath for 1 h to obtain a precursor solution. 1 mL of the precursor solution was repeatedly spin-coated onto the surface of a 2.5 cm diameter, 1.5 mm thick titanium suboxide conductive ceramic film as a copolymer coating layer. The spin-coating process was performed using a spin coater, with a speed of 30 r / min for 10 s followed by a high speed of 600 r / min for 60 s. After drying, an electrically controlled enriched catalytic film was obtained.

[0091] The experimental results are analyzed below:

[0092] Figure 2 a and Figure 2 b are scanning electron microscope images of the surface of the electrically manipulated enriched catalytic membrane prepared in Example 2 and the surface covered with carbon nanotubes. Figure 3 The image shows the porosity results of the electrically controlled enrichment catalytic membrane prepared in Example 2, determined by mercury intrusion porosimetry. CM represents the catalytic membrane without the copolymer coating, while PTMA-CM represents the electrically controlled enrichment catalytic membrane prepared in Example 2 with a spin-coated copolymer coating. Figure 2 a, Figure 2 b and Figure 3 It can be seen that the pore size of the substrate membrane of the electrically controlled enrichment catalytic membrane prepared in Example 2 is slightly less than 1 μm, the copolymer coating layer has little effect on the pore size of the substrate membrane, and carbon nanotubes are used as crosslinking agents to cover the surface of the membrane.

[0093] Figure 4The EPR structures of the electrically manipulated enrichment catalytic membranes containing copolymer coatings with different oxidation degrees prepared in Examples 1-3 and the comparative examples are shown. Stable N=O· radicals can be observed through the EPR results. The signal intensity related to the radical spin density increases with the degree of oxidation, while the hydrophobicity increases, and the adsorption capacity for hydrophobic pollutants increases.

[0094] Figure 5 The CV curve results show that the nitro radicals and NO functional groups on the copolymer coating of the electro-manipulated enriched catalytic membrane prepared in Example 2 have redox reversibility.

[0095] Figure 6 a Figure 6 b represents the removal performance and separation coefficient of three coexisting organic pollutants under different voltage differences. The results show that under the condition of coexistence of the three pollutants, when the electrode membrane is not energized (OC), CBZ has a larger removal capacity compared to the other two pollutants (separation coefficient of 1.645), indicating that the electro-controlled enrichment catalytic membrane preferentially adsorbs CBZ when no current is applied. SMX exhibits larger removal capacities at 1.2 and 2.4 V (separation coefficients of 1.243–1.859), and phenol at 3.6 V (separation coefficient of 2.145). Therefore, target organic pollutants in a coexisting pollution system can be selectively removed by voltage regulation.

[0096] Figure 7 a and Figure 7 Figure b shows the calculated current utilization efficiency and unit energy consumption for removing a specific organic pollutant per mole using an electrically controlled enrichment catalytic membrane system. Taking SMX as an example, with a potential difference of 2.4V, the AC utilization efficiency and unit energy consumption for applying [-0.1, 2.3]V AC current are 1.8 × 10⁻⁶. -2 % and 0.02564 kWh / mol; the AC utilization efficiency and unit energy consumption under applied [-0.5, 1.9] V were 9.6 × 10⁻⁶ kWh / mol. -2 % and 0.02964 kWh / mol. Under the same potential difference, compared with applying AC current of [-0.1, 2.3] V, the catalytic membrane system with AC current of -0.5 V negative bias and 1.9 V positive bias ([-0.5, 1.9] V) has a higher removal rate, higher current utilization efficiency and lower unit energy consumption, thus resulting in lower treatment cost.

[0097] according to Figure 8 It can be seen that when an alternating current of [-0.5, 1.9] V is applied, the membrane with the copolymer coating prepared in Example 2 adsorbs 1.31 to 2.13 times the amount of the three pollutants compared to the comparative example, i.e., the enrichment factor is 1.31 to 2.13. This indicates that the electrically controlled enrichment membrane provided by the present invention can efficiently remove organic pollutants from polluted water bodies.

[0098] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. An application of electrically controlled enrichment catalytic membranes in water treatment, characterized in that, The electrically controlled enrichment catalytic membrane comprises a base membrane and a copolymer coating layer with reversible electro-oxidation-reduction properties; the base membrane is a titanium suboxide conductive ceramic membrane with a pore size of less than 1 micrometer; the copolymer coating layer is made of TMA, an organic blend polymer containing nitro radical functional groups. x -co-TMPMA （1-x） 0 < x < 100, where x% represents the degree of oxidation; details are as follows: Two electrically controlled enrichment catalytic membranes are used as filter membranes in an electrochemical water treatment device, with the two filter membranes connected to the positive and negative electrodes of an AC power system, respectively. The polluted solution is controlled to flow through the two filter membranes in sequence. By adjusting the positive and negative bias parameters on the filter membranes, the hydrophobic organic pollutants in the polluted solution are adsorbed and oxidized for removal.

2. The application of the electrically controlled enrichment catalytic membrane according to claim 1 in water treatment, characterized in that, The value of x is in the range of 18 ≤ x ≤ 84, and the copolymer TMA x -co-TMPMA （1-x） In medium, the degree of oxidation is 18-84%.

3. The application of the electrically controlled enrichment catalytic membrane according to claim 1 in water treatment, characterized in that, The specific preparation method is as follows: S1: 2-Methyl-2-acrylate-2,2,6,6-tetramethyl-4-piperidinyl ester was dissolved in an N,N-dimethylformamide solution after nitrogen blowing to remove oxygen. Then, an azobisisobutyronitrile solution was added under oxygen-free conditions to carry out a polymerization reaction, resulting in a polymer solution. The polymer solution was added to a 20-80 wt.% methanol solution until a first precipitate appeared. The first precipitate was then obtained by filtration and freeze-dried to obtain the polymer PTMPMA. S2: Dissolve the polymer PTMPMA prepared in S1 in a tetrahydrofuran solution, wherein the concentration of polymer PTMPMA is 1~3 g / mL, and after cooling, add it to the oxidant and mix evenly to obtain a mixed solution containing part of the oxidized polymer PTMPMA; the oxidant is a tetrahydrofuran solution of m-chloroperoxybenzoic acid; The mixed solution containing the partially oxidized polymer PTMPMA was added to a sodium hydroxide solution until a second precipitate appeared. The second precipitate was then separated, thoroughly washed, and freeze-dried to obtain copolymers TMA of different oxidation degrees. x -co-TMPMA （1-x） ; S3: The copolymer TMA obtained in S2 x -co-TMPMA （1-x） Carbon nanotubes were dissolved in N,N-dimethylformamide solution at a mass ratio of (1~4):(4~1) to obtain a precursor solution; The precursor solution was repeatedly spin-coated onto the upper surface of the substrate membrane as a copolymer coating layer to obtain an electrically controlled enriched catalytic membrane.

4. The application of the electrically controlled enrichment catalytic membrane according to claim 1 in water treatment, characterized in that, In S1, the concentration of 2-methyl-2-acrylate-2,2,6,6-tetramethyl-4-piperidinyl ester dissolved in N,N-dimethylformamide solution is 40~50 mmol; the concentration of azobisisobutyronitrile in the polymer solution is 2~4 g / L.

5. The application of the electrically controlled enrichment catalytic membrane according to claim 1 in water treatment, characterized in that, In the S2 mixture containing partially oxidized polymer PTMPMA, the mass ratio of polymer PTMPMA to m-chloroperoxybenzoic acid is 10:(0.174~0.995); the concentration of sodium hydroxide solution in the S2 is 0.4~0.6M.

6. The application of the electrically controlled enrichment catalytic membrane according to claim 1 in water treatment, characterized in that, The process of thoroughly washing the second precipitate in S2 is as follows: after dissolving the second precipitate in tetrahydrofuran solution and washing it, it is then thoroughly washed with pure methanol, 20 wt.% methanol and deionized water in sequence to remove the tetrahydrofuran solution.

7. The application of the electrically controlled enrichment catalytic membrane according to claim 1 in water treatment, characterized in that, The volume of the precursor solution for spin coating in S3 is 0.2~2 mL.

8. The application of the electrically controlled enrichment catalytic membrane according to claim 1 in water treatment, characterized in that, The substrate film is a sub-titanium oxide conductive ceramic film with a diameter of 0.5~5 cm and a thickness of 0.2~3 mm.

9. The application of the electrically controlled enrichment catalytic membrane according to claim 1 in water treatment, characterized in that, The spin coating process uses a spin coater, with a rotation speed of 30 r / min for 5 to 30 seconds, followed by a rotation speed of 600 r / min for 30 to 90 seconds.

10. The application of the electrically controlled enrichment catalytic membrane according to claim 1 in water treatment, characterized in that, The hydrophobic organic pollutant is one or more of phenol, sulfamethoxazole, or carbamazepine; the difference between the positive and negative bias voltages ranges from 1.2 to 3.6 V.

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