A PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode for efficient electrocatalytic treatment of oily wastewater and its preparation method

Abstract

The present invention provides a PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode and a preparation method for efficiently electrocatalytically treating oily wastewater, and relates to the technical field of water treatment. The PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode is a ternary composite membrane electrode in which a titanium mesh is modified by titanium oxide and polytetrafluoroethylene, showing hydrophilicity and underwater superoleophobicity, with a water contact angle of 42.9° in air and an underwater oil contact angle of 125.8°. The PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode for efficiently electrocatalytically treating oily wastewater proposed by the present invention is a new type of electrode material that has both hydrophilicity and underwater superoleophobicity, which can not only prevent oil pollution from occupying electrode active sites and maintain efficient oily wastewater treatment, but also reduce the pollution of oil pollution to the electrode and extend the service life of the electrode.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and specifically relates to a PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater and a preparation method thereof. Background Art

[0002] As an important energy storage facility in the power system, pumped storage power stations play a key role in clean energy infrastructure. During the mechanical repairs during construction and the accident maintenance of the units during operation, problems with the hydraulic, lubrication systems and mechanical seals lead to the periodic generation of oily wastewater. These oily wastewaters not only corrode mechanical equipment, affecting their performance and life, but also pollute water bodies and threaten aquatic ecosystems. Therefore, it is extremely important to effectively treat oily wastewater and reduce its negative impact on the environment and equipment.

[0003] At present, the methods for treating oily wastewater include physical methods such as gravity sedimentation, centrifugal separation, flocculation sedimentation, membrane filtration, chemical advanced oxidation methods such as photocatalysis, UV / Fenton, and biodegradation methods such as activated sludge. However, the physical separation method has the problems of low efficiency and secondary treatment of oil pollution; the chemical advanced oxidation method will produce secondary pollution and is costly; the biodegradation method has strict requirements on reaction conditions and the treatment effect is unstable. In recent years, the electrochemical oxidation method has attracted attention for its advantages such as mild reaction conditions, simple operation and maintenance, suitability for the removal of difficult-to-degrade substances and modular operation. The principle of this method is: directly oxidize pollutants by electron transfer on the electrode surface, or generate strong oxidizing free radicals ·OH at the anode interface, and the free radicals ·OH indirectly oxidize the difficult-to-biodegrade organic pollutants. ·OH is a non-selective and highly efficient oxidant (k>10 8 M -1 s -1 ), which can effectively mineralize difficult-to-degrade substances.

[0004] When electrocatalytically treating oily wastewater, the generation of OH and the oxidation degradation of pollutants are mainly concentrated on the anode surface. However, the accumulation of oil pollutants at the electrode interface seriously damages the effective active area and oxidation effect of the electrode, reducing the efficiency of oily wastewater treatment. Summary of the invention

[0005] In view of the defects of the prior art, the present invention provides a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater and a preparation method thereof, which can effectively solve the above problems.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The present invention provides a PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode for efficiently electrocatalytically treating oily wastewater. The PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode is a ternary composite membrane electrode in which a titanium mesh is modified by titanium oxide and polytetrafluoroethylene, exhibits hydrophilicity and underwater superoleophobicity, has a water contact angle of 42.9° in air, and an oil contact angle of 125.8° underwater.

[0008] Preferably, the PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode has strong electrogenerated ·OH activity and ·OH availability, which endows it with electrocatalytic oxidation ability and self-cleaning function.

[0009] The present invention also provides a method for preparing a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater, comprising the following steps:

[0010] Step 1, pretreatment of titanium substrate:

[0011] The surface of the titanium substrate is polished by using sandpaper to obtain a polished titanium substrate;

[0012] A mixed solution of sodium hydroxide and acetone in a volume ratio of 1:1 is prepared, the polished titanium substrate is immersed in the mixed solution, and heated to 80-90° C. for 30-60 minutes to obtain a preliminarily cleaned titanium substrate;

[0013] The titanium substrate after preliminary cleaning is placed in a 10% by mass oxalic acid solution in a slightly boiling state for 2 hours for further cleaning to obtain a cleaned titanium substrate;

[0014] Step 2, preparation of TiSO-Ti film electrode:

[0015] At 60-65V voltage and 600A current, the flow rate is 40-50L·min -1 The argon gas flow rate is 10-12L·min -1 A mixed gas composed of hydrogen is used as a gas source to generate plasma through a plasma torch;

[0016] The fused titanium dioxide TiSO powder with an average particle size of 30 μm was heated in an argon gas flow rate of 3-5 L·min -1 Injected into the generated plasma under the condition of carrier gas;

[0017] At a spray distance of 100-120 mm, using argon as a protective gas, a plasma spraying device is used to uniformly spray titanium dioxide particles in the plasma onto the surface of the cleaned titanium substrate obtained in step 1 to obtain a TiSO-Ti film electrode;

[0018] Step 3, preparation of PTFE-TiSO-Ti ternary composite membrane electrode:

[0019] In the reaction cell, a TiSO-Ti membrane electrode is used as an anode, a stainless steel mesh is used as a cathode, 0.05-0.15M NaClO4 is used as an electrolyte, and titanium dioxide and polytetrafluoroethylene are added to the reaction cell in a molar ratio of 16:1 to 4:1; then, the anode TiSO-Ti membrane electrode is subjected to a current density of 10-30 mA cm-1 under 80°C water bath conditions. -2 , electrofluorination treatment with an anode potential of 2.5-3.8V vsSHE for 30-90min to prepare a PTFE-TiSO-Ti ternary composite membrane electrode with a fluorine atomic mass content of 0.1%-0.4%.

[0020] Preferably, in step 2, the spray angle of the plasma spraying equipment is +10°.

[0021] The present invention also provides an application of the PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater. The PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode is used to construct an electrocatalytic water treatment mode to treat oily wastewater. The specific method is:

[0022] The PTFE-TiSO-Ti ternary composite membrane electrode is used as the anode, and the stainless steel mesh is wrapped around it in a sleeve shape as the cathode. The distance between the anode and the cathode is 0.5-1.2 cm.

[0023] The peristaltic pump drives the oily wastewater to penetrate the PTFE-TiSO-Ti ternary composite membrane electrode in a cross-flow filtration mode to complete the penetrating electrolysis; the membrane flux range is 0-1500LHM, and the current density range is 5-20mA·cm -2 , electrolysis time 0-60min, electrolyte is 0.05-0.15M Na2SO4.

[0024] Preferably, the oily wastewater is oily wastewater containing floating oil and emulsified oil; and the oily wastewater is wastewater containing mechanical lubricating oil pollutants, and the mass concentration of mechanical lubricating oil pollutants is 0-600 mg·L -1 , corresponding to COD of 0-607mg·L -1 .

[0025] The PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode and preparation method for high-efficiency electrocatalytic treatment of oily wastewater provided by the present invention have the following advantages:

[0026] The PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for efficient electrocatalytic treatment of oily wastewater proposed in the present invention is a new type of electrode material that is both hydrophilic and underwater superoleophobic, which can not only prevent oil from invading the active sites of the electrode and maintain efficient oily wastewater treatment, but also reduce the pollution of oil to the electrode and extend the service life of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The SEM images of the pretreated titanium mesh and the titanium mesh coated with TiSO and PTFE at two magnifications; Figure a and Figure b are the pretreated titanium mesh at low and high magnifications, respectively; Figure c and Figure d are the titanium mesh coated with TiSO and PTFE at low and high magnifications, respectively;

[0028] Figure 2 The EDS spectrum of the PTFE-TiSO-Ti ternary composite membrane electrode; the four figures are the total element mapping and the energy spectra of the elements titanium (Ti), oxygen (O), and fluorine (F);

[0029] Figure 3 Schematic diagram of the contact angle of PTFE-TiSO-Ti ternary composite membrane electrode with water in air and with oil underwater;

[0030] Figure 4 The contact angle and rolling angle diagrams of PTFE-TiSO-Ti ternary composite membrane and five oils (hexadecane, 1,2-dichloroethane, n-hexane, toluene, and motor oil);

[0031] Figure 5 Schematic diagram of the oil-water separation effect of the PTFE-TiSO-Ti ternary composite electrode membrane;

[0032] Figure 6 The figure shows the separation efficiency of PTFE-TiSO-Ti ternary composite membrane for oil / water mixtures of five kinds of oils;

[0033] Figure 7 This is the efficiency result diagram of the PTFE-TiSO-Ti ternary composite membrane for the continuous multiple separation processes of hexadecane / water mixture;

[0034] Figure 8 It is a schematic diagram of the reaction device of the present invention;

[0035] Fig. 9 is a perspective view of a reaction device of the present invention;

[0036] Fig.10 The three views of the PTFE-TiSO-Ti ternary composite membrane electrode in the reaction device of the present invention;

[0037] Fig.11The three views of the stainless steel electrode in the reaction device of the present invention;

[0038] Fig.12 The three views of the organic glass reaction cylinder in the reaction device of the present invention;

[0039] Fig.13 Degradation curves of oily wastewater under different current densities;

[0040] Fig.14 XPS spectra of PTFE-TiSO-Ti ternary composite membrane in original state, without electrical plugging, after backwashing and penetration electrolysis. DETAILED DESCRIPTION

[0041] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

[0042] In order to make the objectives, technical solutions and advantages of the embodiments of the present invention more clearly understood, the spirit of the contents disclosed in the present invention will be described in detail below. After understanding the embodiments of the contents of the present invention, any technician in the relevant technical field can change and modify the techniques taught by the contents of the present invention without departing from the spirit and scope of the contents of the present invention.

[0043] The exemplary embodiments of the present invention and the description thereof are used to explain the present invention but are not intended to limit the present invention.

[0044] The present invention provides a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for efficient electrocatalytic treatment of oily wastewater and a preparation method thereof, specifically a fluorine-modified titanium suboxide active membrane electrode for electrocatalytic oxidation wastewater treatment, a preparation method thereof and a flow-through water treatment mode.

[0045] The PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode for efficient electrocatalytic treatment of oily wastewater proposed in the present invention is an efficient self-cleaning PTFE-TiSO-Ti ternary composite membrane electrode, which can effectively solve the problem that floating oil adheres to the electrode surface and occupies active sites, thereby affecting the effect of electrocatalytic oxidation treatment. Among them, the titanium substrate is a Ti mesh substrate, which has hydrophilic / underwater superoleophobic properties and good mechanical strength; TiSO has electrocatalytic activity; the PTFE coating improves the availability and electroactivity of electrogenerated ·OH, and gives the electrode self-cleaning ability. In addition, combined with the penetrating electrolysis method, the ternary membrane electrode of the present invention improves the utilization rate of ·OH and the mass transfer efficiency of floating oil by avoiding direct contact between oil and electrode, and effectively prevents electrode contamination and inactivation. In summary, the present invention not only enhances the efficiency of electrocatalytic treatment of oily wastewater, but also ensures the stability and long-term sustainability of the treatment process.

[0046] Specifically, during the electrocatalytic treatment of oily wastewater, the generation of ·OH and the oxidative degradation of pollutants are mainly concentrated on the anode surface. However, the accumulation of oil pollutants at the electrode interface seriously damages the effective active area and oxidation effect of the electrode. The PTFE-TiSO-Ti ternary composite membrane electrode developed by the present invention exhibits hydrophilicity and underwater superoleophobicity; due to the underwater superoleophobicity, it can effectively prevent the contact between oil and the electrode surface and maintain the activity of the electrode; due to the hydrophilicity, the electrode is in good contact with water, and then the anode electrolyzes water to produce ·OH on the anode surface; in addition, the PTFE-TiSO-Ti ternary composite membrane electrode developed by the present invention improves the affinity for water molecules, thereby effectively avoiding the problem that the electrode is susceptible to the oxygen evolution side reaction due to excessive hydrophilicity, thereby losing the electrode active sites.

[0047] The PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for efficient electrocatalytic treatment of oily wastewater proposed in the present invention is a new type of electrode material that is both hydrophilic and underwater superoleophobic, which can not only prevent oil from invading the active sites of the electrode and maintain efficient oily wastewater treatment, but also reduce the pollution of oil to the electrode and extend the service life of the electrode.

[0048] The present invention provides a PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater. The PTFE-TiSO-Ti ternary hydrophilic / oleophobic penetrating membrane electrode is a ternary composite membrane electrode in which a titanium mesh is modified with titanium oxide and polytetrafluoroethylene, exhibits hydrophilicity and underwater superoleophobicity, has an air / water contact angle of 42.9°, and a water / oil droplet contact angle of 125.8°.

[0049] The PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode has extremely strong electrogenerated ·OH activity and ·OH availability, which endows it with electrocatalytic oxidation ability and self-cleaning function.

[0050] A method for preparing a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater comprises the following steps:

[0051] Step 1, pretreatment of titanium substrate:

[0052] The average pore size of the titanium mesh substrate is 7-8 μm; the surface of the titanium substrate is polished with sandpaper to obtain a polished titanium substrate; in actual use, the surface of the 700-mesh titanium mesh substrate can be polished with coarse sandpaper and fine sandpaper in sequence;

[0053] A mixed solution of sodium hydroxide and acetone in a volume ratio of 1:1 is prepared, the polished titanium substrate is immersed in the mixed solution, and heated to 80-90° C. for 30-60 minutes to obtain a preliminarily cleaned titanium substrate;

[0054] The titanium substrate after preliminary cleaning is placed in a 10% by mass oxalic acid solution in a slightly boiling state for 2 hours for further cleaning to obtain a cleaned titanium substrate;

[0055] Step 2, preparation of TiSO-Ti film electrode:

[0056] At 60-65V voltage and 600A current, the flow rate is 40-50L·min -1 The argon gas flow rate is 10-12L·min -1 A mixed gas composed of hydrogen is used as a gas source to generate plasma through a plasma torch;

[0057] The fused titanium dioxide TiSO powder with an average particle size of 30 μm was heated in an argon gas flow rate of 3-5 L·min -1 Injected into the generated plasma under the condition of carrier gas;

[0058] At a spray distance of 100-120 mm, argon gas is used as a protective gas, and a plasma spraying device is used to uniformly spray titanium suboxide particles in the plasma on the surface of the cleaned titanium substrate obtained in step 1 to obtain a TiSO-Ti film electrode; wherein the spray angle of the plasma spraying device is +10°. During the spraying process, an argon gas protection device can be used to prevent oxidation of the TiSO particles.

[0059] Step 3, preparation of PTFE-TiSO-Ti ternary composite membrane electrode:

[0060] In the reaction cell, a TiSO-Ti membrane electrode is used as an anode, a stainless steel mesh is used as a cathode, 0.05-0.15M NaClO4 is used as an electrolyte, and titanium dioxide and polytetrafluoroethylene are added to the reaction cell in a molar ratio of 16:1 to 4:1; then, the anode TiSO-Ti membrane electrode is subjected to a current density of 10-30 mA cm-1 under 80°C water bath conditions. -2 , electrofluorination treatment with an anode potential of 2.5-3.8V vsSHE for 30-90min to prepare a PTFE-TiSO-Ti ternary composite membrane electrode with a fluorine atomic mass content of 0.1%-0.4%.

[0061] In this step, the reaction cell of the electrofluorination process is an H-type reaction cell, and the anode chamber and the cathode chamber are interconnected.

[0062] The present invention also provides an application of a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater, which is used to treat oily wastewater, wherein the oily wastewater is oily wastewater containing floating oil and emulsified oil; and the oily wastewater is wastewater containing mechanical lubricating oil pollutants, and the mass concentration of the mechanical lubricating oil pollutants is 0-600 mg·L -1 , corresponding to COD of 0-607mg·L -1 .

[0063] The PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode is used to construct an electrocatalytic water treatment mode to treat oily wastewater. The specific method is as follows:

[0064] A PTFE-TiSO-Ti ternary composite membrane electrode is used as an anode, and a stainless steel mesh is wrapped around it in a sleeve shape as a cathode, and the distance between the anode and the cathode is 0.5-1.2 cm; for example, the distance is 0.7 cm;

[0065] The peristaltic pump drives the oily wastewater to penetrate the PTFE-TiSO-Ti ternary composite membrane electrode in a cross-flow filtration mode to complete the penetrating electrolysis; the membrane flux range is 0-1500LHM, and the current density range is 5-20mA·cm -2 , electrolysis time 0-60min, electrolyte is 0.05-0.15M Na2SO4.

[0066] Take oily wastewater as the mass concentration of 0-600mg·L -1 (Corresponding COD is 0-607mg·L -1 ) as an example, the wastewater is driven by a peristaltic pump to penetrate the membrane electrode in the form of cross-flow filtration to realize the penetrating electrolysis mode. The effluent is extracted from the top of the reactor and recycled. During the reaction process, the membrane flux range is 0-1500LHM. When the membrane flux is 0LHM, that is, no water flows through the membrane electrode, it is mainly a pollutant diffusion control process. At this time, the electrocatalytic oxidation belongs to the sequencing batch water treatment mode. With the increase of membrane flux, the flow-through water treatment mode is turned on, that is, the mass transfer capacity is improved, and the electrocatalytic oxidation process will change from a pollutant diffusion control process to an electrocatalytic oxidation kinetic control process. Direct current is used as the power supply, and the current density range is 0.05-0.2mA·cm -2 When the potential is less than 2.38V vs SHE, it is an electrochemical direct oxidation, that is, a direct electron transfer process occurs. When the potential is greater than 2.38V vs SHE, it is an indirect oxidation process, that is, the electrically active species hydroxyl radical (·OH) can participate in the pollution oxidation.

[0067] The present invention provides a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for efficient electrocatalytic treatment of oily wastewater, and the main materials of the electrode include titanium film electrode, titanium oxide and polytetrafluoroethylene. Among them, the titanium film electrode is used as the substrate of the composite electrode with its good strength and hardness; titanium oxide TiSO has the advantages of strong conductivity, low cost, oxygen evolution potential (2.6Vvs SHE) comparable to that of BDD electrode, and is used to trigger electrocatalytic reaction to degrade oil pollution; polytetrafluoroethylene PTFE can introduce F atoms to the composite electrode on the one hand, significantly increase the oxygen evolution overpotential of the composite electrode, inhibit oxygen evolution side reaction, and promote the desorption of OH on the interface. On the other hand, polytetrafluoroethylene has both super hydrophobic and super oleophobic properties. Modifying polytetrafluoroethylene in a certain proportion can make the electrode hydrophilic and underwater super oleophobic. The ternary PTFE-TiSO-Ti composite structure electrode finally obtained can not only remove oil efficiently, but also has hydrophilicity and underwater super oleophobicity, and has self-cleaning ability.

[0068] An embodiment is described below:

[0069] Pretreatment of the titanium substrate: the surface of the tubular porous titanium substrate is polished with coarse sandpaper and fine sandpaper in turn;

[0070] A mixed solution of sodium hydroxide and acetone in a volume ratio of 1:1 is prepared, and the polished titanium substrate is immersed in the mixed solution, and heated to 80° C. for 50 minutes to obtain a preliminarily cleaned titanium substrate;

[0071] The titanium substrate after preliminary cleaning is placed in a 10% by mass oxalic acid solution in a slightly boiling state for 2 hours for further cleaning to obtain a cleaned titanium substrate for standby use.

[0072] Step 2, preparation of TiSO-Ti film electrode:

[0073] At 60V voltage and 600A current, the flow rate is 45L·min -1 The argon gas flow rate is 12 L min -1 A mixed gas composed of hydrogen is used as the gas source, and plasma is generated by a plasma torch.

[0074] The fused titanium dioxide powder with an average particle size of 30 μm was heated in an argon gas flow rate of 4 L min -1 Injected into the generated plasma under the condition of carrier gas;

[0075] At a spray distance of 120 mm, argon was used as the protective gas, and a plasma spraying device was used to uniformly spray the titanium oxide particles in the plasma onto the surface of the cleaned titanium substrate obtained in step 1 to prepare a tubular TiSO-Ti membrane electrode having a length of 10 cm, an inner diameter of 2.5 cm, an outer diameter of 3 cm, and a membrane electrode thickness of 0.5 cm.

[0076] Step 3, preparation of PTFE-TiSO-Ti ternary composite membrane electrode:

[0077] In the reaction cell, the TiSO-Ti membrane electrode was used as the anode, the stainless steel mesh was used as the cathode, 0.05-0.15M NaClO4 was used as the electrolyte, titanium dioxide and polytetrafluoroethylene were added in a molar ratio of 12:1 into the reaction cell, and then the anode was charged at a current density of 20 mA cm-1 under 80 °C water bath conditions. -2 , and electro-fluorination treatment for 60 minutes at an anode potential of 3.3 V vs SHE. After the reaction, a PTFE-TiSO-Ti ternary composite membrane electrode with a fluorine atomic mass content of 0.3% was obtained.

[0078] The surface morphology of the pretreated titanium substrate (i.e., Ti membrane electrode) and the PTFE-TiSO-Ti ternary composite membrane electrode were analyzed by SEM, and the PTFE-TiSO-Ti ternary composite membrane electrode was analyzed by EDS.

[0079] like Figure 1 As shown, these are SEM images of the pretreated titanium substrate and the titanium mesh coated with TiSO and PTFE; wherein, Figure a is the SEM image of the pretreated titanium mesh; Figure b is the SEM image of the titanium mesh at a high magnification; Figure c is the SEM image of the titanium mesh coated with TiSO and PTFE; Figure d is the SEM image of the titanium mesh coated with TiSO and PTFE at a high magnification.

[0080] As can be seen from Figure a, the surface of the titanium mesh without TiSO coating is regularly distributed with surface openings composed of relatively smooth titanium wire fibers. As can be seen from Figure c, the coated titanium mesh maintains the original regular and orderly surface structure, and from the high-magnification SEM image of Figure d, it can be seen that the surface of the titanium wire fibers is uniformly and densely wrapped with a layer of fine titanium suboxide particles, without a fragile structure. This uniform and dense coating has good mechanical stability and can be used for the treatment of actual oily wastewater.

[0081] like Figure 2 , is the EDS image of PTFE-TiSO-Ti ternary composite membrane electrode. Figure 2 It can be seen that titanium dioxide and polytetrafluoroethylene have been successfully modified on the surface of the titanium film electrode.

[0082] The contact angle and rolling angle of the prepared PTFE-TiSO-Ti ternary composite membrane electrode were tested using a contact angle meter. Five oils, including hexadecane, ethyl chloride, n-hexane, toluene, and motor oil, were selected for testing. Figure 3 As shown, it is a schematic diagram of the contact angle of PTFE-TiSO-Ti ternary composite membrane electrode with water in air and the contact angle of oil under water; Figure 4 As shown in Figure 1, it is a schematic diagram of the contact angle and rolling angle of PTFE-TiSO-Ti ternary composite membrane with various oils; Figure 3 and Figure 4 It can be seen that the contact angles of the finally prepared PTFE-TiSO-Ti ternary composite membrane electrode with water in the air and oil underwater are 42.9° and 125.8°, respectively, which are hydrophilic and superoleophobic. Underwater, except for 1,2-dichloroethane, the contact angles of hexadecane, n-hexane, toluene and motor oil on the membrane surface are 156.2±2.9°, 151.0±2.5°, 152.7±2.4° and 150.6±1.1°, respectively. This illustrates the underwater superoleophobic properties of the TiSO and PTFE coated membranes. In addition, the rolling angles of the five oils tested on the membrane surface did not exceed 2.5°, indicating that the coated titanium mesh surface has a lower adhesion to the oil. When conducting electrocatalytic treatment of oily wastewater, the possibility of oil contamination on the membrane surface can be reduced, ensuring the service life of the electrode material.

[0083] As Figure 5 The device shown in the figure is used to perform an oil-water separation experiment on a PTFE-TiSO-Ti ternary composite membrane electrode. The PTFE-TiSO-Ti ternary composite membrane electrode-shaped membrane is fixed between the upper and lower parts of the device, and the effective separation area is 2 cm 2 Before separation, the membrane was pre-wetted with 2 mL of water to prevent the oil phase in the oil / water mixture from directly contacting the membrane. After the oil / water mixture was added, the water passed through the membrane pores and was collected in the vial at the bottom of the device, while the oil in the mixture was trapped in the upper part of the device. The above separation-cleaning process was repeated several times to evaluate the reusability of the mesh membrane with TiSO and PTFE coating. Figure 6 As shown in Figure 2, the separation efficiency of PTFE-TiSO-Ti ternary composite membrane for different types of oil / water mixtures; Figure 7 As shown in Figure 2, the separation efficiency of the PTFE-TiSO-Ti ternary composite membrane for the hexadecane / water mixture during multiple separations. Figure 6 and Figure 7As shown in the figure, the membrane coated with TiSO and PTFE has a high oil-water separation efficiency. The separation efficiency of hexadecane, 1,2-dichloroethane, n-hexane, toluene and the mixture of engine oil and water tested in the experiment is as high as 99.5%, 99.3%, 99.5%, 99.9% and 99.9%, respectively. In addition, during the multiple hexadecane / water separation processes, the separation efficiency did not decrease significantly and remained above 99.3%. The above results show that the mesh membrane coated with TiSO and PTFE has extremely strong and stable underwater oleophobicity, and can maintain good anti-oil pollution performance under complex water conditions, thereby ensuring the service life of the electrode material.

[0084] like Figure 8 and Fig. 9 The figure shows a schematic diagram of a flow-through water treatment reactor for constructing a PTFE-TiSO-Ti ternary composite membrane electrode. Component 1 is a PTFE-TiSO-Ti ternary composite membrane electrode; component 2 is a stainless steel sleeve; component 3 is an organic glass reaction cylinder; Fig.10 Three views of PTFE-TiSO-Ti ternary composite membrane electrode; Fig.11 This is the three-view drawing of the stainless steel electrode; Fig.12 These are three views of the plexiglass reaction cylinder.

[0085] When the reactor was running, the PTFE-TiSO-Ti ternary composite membrane electrode was used as the anode, and the stainless steel mesh was wrapped around the PTFE-TiSO-Ti ternary composite membrane electrode in a sleeve shape as the cathode. The distance between the two was 0.7 cm. The concentration was 600 mg·L -1 The lubricating oil simulates the pollutant, and 0.12M Na2SO4 is used as the electrolyte. The raw water is pumped out from the top of the membrane electrode at different flow rates through the peristaltic pump, forcing the water to flow through the membrane electrode, and the water at the end is recycled. Fig.13 The degradation curves of oily wastewater under different current densities are shown in Figure 2. In the 60-min sequencing batch water treatment mode, the current density is 5, 10, 15, and 20 mA cm -2 When PTFE-TiSO-Ti (3.93V vs SHE) was used, the removal rates of lubricating oil by PTFE-TiSO-Ti (3.93V vs SHE) were 47.2%, 62.13%, 83.33% and 90.6% respectively.

[0086] When conducting an oil-water separation experiment for oily wastewater, the degradation performance of the PTFE-TiSO-Ti ternary composite membrane on surface oil pollution was tested. First, the membrane after oil-water separation was hydraulically backwashed to eliminate the influence of particulate pollutants accumulated on its surface or in the pores, and then it was electrocatalytically oxidized. XPS was used to characterize the degradation ability of the TiO2 coating on organic pollutants in actual wastewater adsorbed on the surface under the assistance of ultraviolet light. Fig.14The following are the XPS spectra of the PTFE-TiSO-Ti ternary composite membrane in its original state, without electrical plugging, after backwashing and after penetration electrolysis. Fig.14 It can be seen that after oil-water separation, the intensity of the Ti2p peak on the surface of the PTFE-TiSO-Ti ternary composite membrane decreased compared with the original state, while the intensity of the C1s peak increased. After backwashing, the intensity of the Ti2p peak returned to the original level of the membrane, but the intensity of the C1s peak was still higher than the original state, indicating that there were still C-containing substances remaining on the membrane surface after backwashing. When the membrane after backwashing was electrocatalytically oxidized, it was found that the intensity of the C1s peak was reduced compared with the membrane after backwashing, and the peak intensities of C1s, Ti2p and O1s were basically consistent with the original state of the membrane, proving that the organic matter remaining on the membrane surface was degraded. The above results show that after the TiO2-coated mesh membrane is contaminated by oil in oily wastewater, the organic pollutants can be effectively removed under the electrocatalytic oxidation reaction to achieve membrane regeneration, thereby avoiding the accumulation of organic pollutants and allowing the membrane to maintain surface wetting characteristics and underwater superoleophobicity.

[0087] The PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode of the present invention is a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater, relates to the field of water treatment, and can be applied to oily wastewater generated during the operation and maintenance of various machines such as pumped storage power stations, and overcomes the challenges of existing electrocatalytic oxidation treatment of oily wastewater, such as the electrode being directly deactivated by oil pollution, resulting in poor electrogenerated OH activity, availability and utilization, and limited treatment efficiency.

[0088] The present invention has the following beneficial effects:

[0089] (1) The present invention solves the problem of electrode contamination and inactivation in oily wastewater treatment by constructing a hydrophilic and underwater superoleophobic PTFE-TiSO-Ti ternary composite membrane electrode to avoid direct contact between oil and the electrode, thereby extending the service life of the electrode, improving the stability and durability of the electrolytic water treatment system, and reducing the maintenance requirements of the system.

[0090] (2) The present invention uses a penetrating electrolysis mode to enhance the mass transfer efficiency of floating oil to the electrode surface, improve the utilization rate of OH, and accelerate the oxidative degradation of oily wastewater.

[0091] (3) The present invention avoids the direct contact between oil and electrode, thus avoiding the inactivation of electrode active sites, improving the availability and electrical activity of ·OH, and giving the electrode self-cleaning ability.

[0092] (4) The present invention can effectively treat oily pollutants until they are mineralized, and no other toxic or harmful substances are produced during the treatment process. The membrane electrode mainly controls the oily wastewater treatment capacity by controlling the current density and the water inlet flow rate. The process is both environmentally friendly and efficient, and is simple to operate and suitable for large-scale applications.

[0093] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be considered as the scope of protection of the present invention.

Claims

1. A PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for efficient electrocatalytic treatment of oily wastewater, characterized in that: The PTFE-TiSO-Ti ternary hydrophilic / oleophobic transmissive membrane electrode is a ternary composite membrane electrode in which a titanium mesh is modified with titanium dioxide and polytetrafluoroethylene, exhibiting hydrophilicity and underwater superoleophobicity, with a water contact angle of 42.9° in air and an underwater oil contact angle of 125.8°. The PTFE-TiSO-Ti ternary hydrophilic / oleophobic transmissive membrane electrode has strong electrogenerated ·OH activity and ·OH availability, giving it electrocatalytic oxidation ability and self-cleaning function.

2. A method for preparing a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater according to claim 1, characterized in that: The following steps are involved: Step 1, pretreatment of titanium substrate: The surface of the titanium substrate is polished by using sandpaper to obtain a polished titanium substrate; A mixed solution of sodium hydroxide and acetone in a volume ratio of 1:1 is prepared, the polished titanium substrate is immersed in the mixed solution, and heated to 80-90° C. for 30-60 minutes to obtain a preliminarily cleaned titanium substrate; The titanium substrate after preliminary cleaning is placed in a 10% by mass oxalic acid solution in a slightly boiling state for 2 hours for further cleaning to obtain a cleaned titanium substrate; Step 2, preparation of TiSO-Ti film electrode: At 60-65V voltage and 600A current, the flow rate is 40-50L·min -1 The argon gas flow rate is 10-12L·min -1 A mixed gas composed of hydrogen is used as a gas source to generate plasma through a plasma torch; The fused titanium dioxide TiSO powder with an average particle size of 30 μm was heated in an argon gas flow rate of 3-5 L·min -1 Injected into the generated plasma under the condition of carrier gas; At a spray distance of 100-120 mm, using argon as a protective gas, a plasma spraying device is used to uniformly spray titanium dioxide particles in the plasma onto the surface of the cleaned titanium substrate obtained in step 1 to obtain a TiSO-Ti film electrode; Step 3, preparation of PTFE-TiSO-Ti ternary composite membrane electrode: In the reaction cell, a TiSO-Ti membrane electrode is used as an anode, a stainless steel mesh is used as a cathode, 0.05-0.15M NaClO4 is used as an electrolyte, and titanium dioxide and polytetrafluoroethylene are added to the reaction cell in a molar ratio of 16:1 to 4:1; then, the anode TiSO-Ti membrane electrode is subjected to a current density of 10-30 mA cm-1 under 80°C water bath conditions. -2 , electrofluorination treatment with an anode potential of 2.5-3.8 V vs SHE for 30-90 min to prepare a PTFE-TiSO-Ti ternary composite membrane electrode with a fluorine atomic mass content of 0.1%-0.4%.

3. The method for preparing a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater according to claim 2, characterized in that: In step 2, the spray angle of the plasma spraying equipment is +10°.

4. An application of a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater according to claim 1, characterized in that: The PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode is used to construct an electrocatalytic water treatment mode to treat oily wastewater. The specific method is as follows: The PTFE-TiSO-Ti ternary composite membrane electrode is used as the anode, and the stainless steel mesh is wrapped around it in a sleeve shape as the cathode. The distance between the anode and the cathode is 0.5-1.2 cm. The peristaltic pump drives the oily wastewater to penetrate the PTFE-TiSO-Ti ternary composite membrane electrode in a cross-flow filtration mode to complete the penetrating electrolysis; the membrane flux range is 0-1500LHM, and the current density range is 5-20mA·cm -2 , electrolysis time 0-60min, electrolyte is 0.05-0.15M Na2SO4.

5. The use of a PTFE-TiSO-Ti ternary hydrophilic / oleophobic permeable membrane electrode for high-efficiency electrocatalytic treatment of oily wastewater according to claim 4, characterized in that: The oily wastewater is oily wastewater containing floating oil and emulsified oil; and the oily wastewater is wastewater containing mechanical lubricating oil pollutants, and the mass concentration of mechanical lubricating oil pollutants is 0-600 mg·L -1 , corresponding to COD of 0-607mg·L -1 .

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