Electrochemical self-heating pressurized inorganic membrane high-efficiency cleaning method

Abstract

The application discloses an electrochemical self-heating pressurized inorganic membrane high-efficiency cleaning method. The high-efficiency cleaning technology comprises pre-flushing, inorganic membrane vacuum-induced ion liquid immersion, closed electrochemical cleaning and post-flushing steps. The application mainly aims at removing inorganic membrane hole organic pollution (such as macromolecular organic matter, humus and the like), and can realize regeneration of inorganic membrane channels which cannot be dredged by conventional flushing. The application is characterized in that the electrochemical pressurized cleaning in a closed environment (without external pressure, and the pressurization is generated by volume expansion of water electrolysis gasification), through alternating current / direct current power supply mode switching, promotes generation of electrochemical heat effect and oxygen molecule activation 'wet type oxidation' cleaning mode, and combines activation of chlorine ions to generate chloro-oxidation free radicals. Compared with normal pressure cleaning, the molecular activity is stronger, the physical and chemical reaction is more violent, and the cleaning efficiency is higher.

Description

TECHNICAL FIELD

[0001] The application relates to an electrochemical self-thermal pressurization inorganic membrane high-efficiency cleaning method and belongs to the technical field of sewage treatment and the field of membranes. BACKGROUND

[0002] Compared with organic membranes, inorganic membranes such as ceramic membranes and aluminum oxide filter membranes have more extreme and harsh application environments, such as high-pressure separation and purification of high-concentration complex organic wastewater. Because of the stability of the material, the inorganic membrane can be cleaned with a higher concentration of chemicals to remove the blocked pollutants and bacteria in the pores. However, with the increase of the service life of the inorganic membrane, it is difficult to remove stubborn organic blockage in the deep pore channel by using conventional physical flushing and chemical cleaning, especially macromolecular and polycyclic aromatic hydrocarbon refractory organic pollutants. One of the main reasons is that the macromolecules and high-valent metal ions (calcium ions, etc.) in water form stable complexes, forming complex blockage pollution, increasing the molecular weight and stabilizing the physical and chemical properties. Secondly, polycyclic aromatic hydrocarbons and heterocyclic macromolecular pollutants have strong oxidation resistance, and the conventional chemical cleaning is difficult to destroy the molecular structure, and the accumulation of days and months forms a large molecular blockage wall in the inorganic membrane pores. In view of the blockage of stubborn organic pollutants in the inorganic membrane pores and the difficulty in cleaning by conventional methods, more effective cleaning technology for organic pollutants in the pores needs to be developed to restore the flux of the inorganic membrane and prolong the service life. SUMMARY

[0003] In order to solve the problem of irreversible macromolecular organic pollution blockage in the membrane pores of the inorganic membrane caused by long-term use under high operating pressure and complex water quality, and to solve the problem of low cleaning ability of conventional inorganic membrane (forward / backward) flushing and chemical cleaning for stubborn high-complexity and refractory macromolecular pollutants in the membrane pores, the application provides an electrochemical self-thermal pressurization inorganic membrane high-efficiency cleaning technology method. By constructing a closed environment filled with chloride ion liquid "electrode-inorganic membrane-electrode", water electrolysis bubble pressurization and active high-oxidation free radicals are generated under the joint action of voltage excitation and electrode catalysis, the inorganic membrane cavity is cleaned under pressure, and the closed environment is cleaned by "wet oxidation" and active chlorine. Compared with normal pressure cleaning, the molecule is more active, the physical and chemical reaction is more violent, and the cleaning efficiency is higher.

[0004] In order to solve the above technical problems, the technical scheme provided by the application is: an electrochemical self-thermal pressurization inorganic membrane high-efficiency cleaning method, which comprises pre-flushing, inorganic membrane vacuum induction ion liquid infiltration, closed electrochemical cleaning and post-flushing, and the specific steps are as follows:

[0005] (1) pre-flushing step, i.e. the inorganic membrane after long-term organic pollution is subjected to conventional forward flushing and back flushing, the forward flushing pressure is equal to the inorganic membrane filtration pressure, the back flushing pressure is 2-4 times of the forward flushing pressure; the forward flushing time is 30-90 min, the back flushing time is 60-120 min; after flushing, the membrane is placed in air or heated environment for drying.

[0006] (2) inorganic membrane vacuum induction ionic liquid infiltration step, i.e. the dried inorganic membrane is placed in a closed container, the vacuum valve is opened, the pressure in the container is extracted to-0.08 Mpa or lower; the vacuum valve is closed, the ionic liquid inlet valve is opened, the inorganic electrolyte solution containing chloride ions is poured into the vacuum container until the liquid level exceeds the top end of the inorganic membrane; the vacuum valve is opened, the pressure is released, and the soaking time is 30-60 min;

[0007] (3) closed electrochemical cleaning step, i.e. electrode pairs are placed on both sides of the inorganic membrane and are compacted by a sealing ring to form a closed space of electrode-ceramic membrane-electrode; the electrode is a water-impermeable electrode sheet, and the electrode area is not less than the inorganic membrane area,

[0008] In the closed electrochemical cleaning step, the electrodes are connected to alternating current, the alternating voltage is 220-380 V, and the alternating current charge is conducted to the ionic liquid through the electrode surface, thereby promoting the generation of alternating current oscillation in the closed space containing the inorganic membrane to rapidly produce heat, heating the water temperature to 60-80℃; the alternating current is switched to direct current, the direct current voltage is 5-30 V, the positive and negative electrodes are switched every 10-20 min, when the water temperature in the closed space is lower than 50℃ at the end of a cycle of direct current, the alternating current is switched back to heat to the required temperature, and then the direct current is switched back; the total running time of the direct current is not more than 2 hours; after the operation is completed, the motor electrode and the sealing ring are removed, and the inorganic membrane is placed for 5-15 min;

[0009] (4) post-flushing step, i.e. the inorganic membrane is placed in a clean water environment, soaked for 20-60 min, then forward flushed for 20-60 min, and back flushed for 20-60 min.

[0010] Preferably, the inorganic electrolyte solution containing chloride ions is sodium chloride, potassium chloride or dilute hydrochloric acid, and the concentration is 10-50 g / L.

[0011] Preferably, the electrode base can be a titanium corrosion-resistant base.

[0012] Preferably, the electrode catalytic layer can be ruthenium, lead, tin electrochemically active oxide.

[0013] Preferably, the sealing ring can be an insulating rubber organic polymer.

[0014] Preferably, the specific steps are:

[0015] (1) The inorganic membrane after long-term organic pollution is subjected to regular forward flushing and back flushing, the forward flushing pressure is equal to the inorganic membrane filtration pressure, the back flushing pressure is twice the forward flushing pressure; the forward flushing time is 30 min, the back flushing time is 60 min; after flushing, the membrane is placed in an air environment at 40℃ for drying;

[0016] (2) The dried inorganic membrane is placed in a closed container, a vacuum valve is opened, the pressure in the container is extracted to -0.08 Mpa or lower; the vacuum valve is closed, an ion liquid water inlet valve is opened, 30 g / L sodium chloride solution is poured into the vacuum container until the liquid level is above the top end of the inorganic membrane; the vacuum valve is opened, the pressure is released, and the soaking time is 30 min. An electrode pair is placed on both sides of the inorganic membrane, the electrode material is titanium-based ruthenium oxide coated electrode, and the electrode is compacted by a sealing ring to form a closed space of electrode-ceramic membrane-electrode; the electrode is a water-tight electrode sheet, the electrode area is not less than the inorganic membrane area, the electrode base can be a titanium base, and the electrode catalytic layer is lead dioxide. The sealing ring is made of insulating rubber. The electrodes are connected to an alternating current, the alternating voltage is 220V, and the alternating charge is conducted to the ion liquid through the electrode surface, thereby causing the closed space containing the inorganic membrane to generate alternating current oscillation and rapid heat generation, and the water temperature is heated to 70℃; the alternating current is switched to direct current, the direct current voltage is 10V, and the positive and negative electrodes are switched every 10 min; if the water temperature in the closed space is lower than 50℃ after 10 min, the alternating current heating is switched back to 70℃, and then switched back to direct current. The total running time of the second step is 1 hour; after the operation is completed, the motor and the sealing ring are removed, and the inorganic membrane is placed for 10 min;

[0017] (3) The inorganic membrane is placed in a clean water environment and soaked for 30 min, then forward flushed for 30 min and back flushed for 60 min.

[0018] Beneficial effects:

[0019] The application discloses an electrochemical self-heating pressurized inorganic membrane high-efficiency cleaning method. The high-efficiency cleaning technology comprises pre-flushing, inorganic membrane vacuum induction ionic liquid immersion, closed electrochemical cleaning and post-flushing steps. The pre-flushing step comprises inorganic membrane positive flushing and back flushing, and drying after flushing; the inorganic membrane vacuum induction ionic liquid immersion step is that the dried inorganic membrane is placed in a vacuum device to extract to a certain vacuum degree, then a chlorine-containing ionic liquid is added into the device until the inorganic membrane piece is immersed, and the ionic liquid is promoted to enter and fill the internal cavity of the inorganic membrane through pressure release; the closed electrochemical cleaning step is that electrode pairs are placed on both sides of the ceramic membrane piece, and a closed space of electrode-ceramic membrane piece-electrode is formed through compaction of a sealing ring, under alternating current power supply, rapid heat production in the closed interval is formed, and when direct current power supply is switched, pressure bubble impact membrane holes are formed on the electrode surface, meanwhile, active chlorine free radicals are formed by conversion of chlorine ions by the anode, and organic matters in the holes are further oxidized, so that the cleaning and dredging of the holes blocked by organic matters in the internal structure of the inorganic membrane are realized. The post-flushing step is that the inorganic membrane is placed in a clean water environment, and positive and back flushing are carried out for a certain time, and the recovery of the membrane flux is completed. The electrochemical high-efficiency cleaning technology and method for organic matters in the holes of the inorganic membrane designed by the application mainly aims at removing organic pollution (such as macromolecular organic matters and humus) in the holes of the inorganic membrane, and can realize the regeneration of the inorganic membrane holes which cannot be dredged by conventional flushing. The method is characterized in that the electrochemical pressure cleaning in a closed environment (without external pressure, and the pressurization is caused by the volume expansion of water electrolysis gasification) is realized, the alternating current / direct current power supply mode is switched to promote the electrochemical heat effect and the oxygen molecule activation "wet type oxidation" cleaning mode, and the chlorine oxidation free radicals are generated by the activation of chlorine ions. Compared with normal pressure cleaning, the molecular activity is stronger, the physical and chemical reaction is more violent, and the cleaning efficiency is higher.

[0020] The electrochemical self-heating pressurized inorganic membrane high-efficiency cleaning method provided by the application constructs a closed space of electrode-inorganic membrane-electrode, and in the space full of ionic liquid, electrochemistry is taken as the core to generate a series of high-energy reactions including alternating current oscillation heat production, direct current water molecule decomposition gasification pressurization, oxygen molecule activation and chlorine ion activation, so that the macromolecular organic matters in the holes of the inorganic membrane are subjected to "wet type oxidation" and free radical oxidation decomposition reaction under high pressure and high heat, and the high-efficiency breaking, degradation and removal of the blocked pollutants in the holes are promoted. Compared with traditional water flushing, chemical washing and other inorganic membrane cleaning processes, the method has the characteristics of strong cleaning capacity and high flux recovery degree. BRIEF DESCRIPTION OF DRAWINGS

[0021] The application will be further described below in combination with the drawings.

[0022] Figure 1 Pre-flushing step of inorganic membrane

[0023] Figure 2 Vacuum immersion step of inorganic membrane

[0024] Figure 3 Pressure relief soaking

[0025] Figure 4 "Electrode-inorganic membrane-electrode" closed space construction schematic

[0026] Figure 5 Power connection schematic

[0027] Figure 6 AC-DC power supply mode switching schematic

[0028] Figure 7 Electrochemical self-heating pressurization principle

[0029] Figure 8 Electrochemical self-heating pressurization activation principle

[0030] Figure 9 Degradation of inorganic membrane pore contaminants schematic

[0031] Figure 10 Inorganic membrane post-rinse step DETAILED DESCRIPTION

[0032] Example 1

[0033] Electrochemical self-heating pressurization inorganic membrane efficient cleaning step

[0034] First, the inorganic membrane after long-term organic pollution is subjected to conventional forward flushing and backwashing, the forward flushing pressure is equal to the inorganic membrane filtration pressure, and the backwashing pressure is twice the forward flushing pressure. The forward flushing time is 30 min, and the backwashing time is 60 min. After flushing, the membrane is placed in an air environment at 40°C for drying.

[0035] Second step, place the dried inorganic membrane in a closed container, open the vacuum valve, and reduce the pressure in the container to -0.08 MPa. Close the vacuum valve and open the ion liquid water valve. Fill the vacuum container with a 30 g / L sodium chloride solution until the liquid level is above the top of the inorganic membrane. Open the vacuum valve and release the pressure. Soak for 30 minutes. Place electrodes on both sides of the inorganic membrane, with the electrodes being titanium-based ruthenium oxide-coated electrodes. Press the electrodes against the ceramic membrane using a sealing ring to form a closed space between the electrodes, ceramic membrane, and electrodes. The electrodes are water-impermeable and have an area that is not less than that of the inorganic membrane. The electrode substrate can be titanium, and the electrode catalytic layer is ruthenium dioxide. Connect the electrodes to an alternating current source with a voltage of 220 V. The alternating current charge is conducted through the electrode surface to the ion liquid, thereby generating rapid heat in the closed space containing the inorganic membrane, and heating the water to 70°C. Switch the alternating current to direct current with a voltage of 10 V. Switch the positive and negative electrodes every 10 minutes. If the water temperature in the closed space is less than 50°C after 10 minutes, switch back to alternating current heating to 70°C, and then switch back to direct current. The total running time of the second step is 1 hour. After the operation is completed, remove the motor and sealing ring, and let the inorganic membrane stand for 10 minutes.

[0036] Third step, place the inorganic membrane in a clean water environment and soak for 30 minutes. Then, rinse for 30 minutes and backwash for 60 minutes.

[0037] Example 2:

[0038] Electrochemical self-heating pressurized inorganic membrane high-efficiency cleaning step

[0039] First step, perform regular forward and backwashing of the inorganic membrane contaminated by organic matter for a long time. The forward washing pressure is equal to the filtration pressure of the inorganic membrane, and the backwashing pressure is 3 times the forward washing pressure. The forward washing time is 40 minutes, and the backwashing time is 40 minutes. After washing, dry the membrane in a 50°C air environment.

[0040] Second step, place the dried inorganic membrane in a closed container, open the vacuum valve, and reduce the pressure in the container to -0.09 Mpa. Close the vacuum valve, open the ion liquid water valve, and fill the container with 50 g / L sodium chloride solution until the liquid level reaches the top of the inorganic membrane. Open the vacuum valve, release the pressure, and soak for 60 min. Place electrodes on both sides of the inorganic membrane and press them together with a sealing ring to form a closed space between the electrodes, ceramic membrane, and electrodes. The electrodes are water-impermeable and have an area not less than that of the inorganic membrane. The electrode substrate can be titanium, and the electrode catalytic layer is lead dioxide. The sealing ring is made of insulating rubber. Connect the electrodes to an alternating current with a voltage of 380 V, and the alternating current charge is conducted to the ion liquid through the electrode surface, thereby generating an alternating current oscillation in the closed space containing the inorganic membrane to rapidly produce heat and heat the water to 70°C. Switch the alternating current to direct current with a voltage of 15 V, and switch the positive and negative electrodes every 15 min. If the water temperature in the closed space is below 50°C after 15 min, switch back to alternating current heating to 60°C, and then switch back to direct current. The total running time of the second step is 1 hour. After the operation is completed, remove the motor and sealing ring, and let the inorganic membrane stand for 15 min.

[0041] Third step, place the inorganic membrane in a clean water environment and soak for 45 min, then rinse for 45 min, and backwash for 60 min.

[0042] Example 3

[0043] First step, perform regular forward and backwashing of the inorganic membrane contaminated by long-term organic pollution. The forward washing pressure is equal to the filtration pressure of the inorganic membrane, and the backwashing pressure is 3 times the forward washing pressure. The forward washing time is 40 min, and the backwashing time is 40 min. After washing, place the membrane in a 50°C air environment for drying.

[0044] Second step, put the dried inorganic membrane into a closed container, open the vacuum valve, and reduce the pressure in the container to -0.09 Mpa. Close the vacuum valve, open the ion liquid water valve, and pour 50g / L potassium chloride solution into the vacuum container until the liquid level is above the top end of the inorganic membrane. Open the vacuum valve, release the pressure, and soak for 60 minutes. Place electrodes on both sides of the inorganic membrane and press them together with a sealing ring to form a closed space of electrode-ceramic membrane-electrode. The electrodes are water-impermeable electrode sheets with an area not less than that of the inorganic membrane. The electrode substrate can be a titanium substrate, and the electrode catalytic layer is lead dioxide. The sealing ring is made of insulating rubber. Connect the electrodes to an alternating current with a voltage of 380V, and the alternating current charge is conducted to the ion liquid through the electrode surface, thereby generating an alternating current oscillation in the closed space containing the inorganic membrane to quickly produce heat and heat the water to 70℃. Switch the alternating current to direct current with a voltage of 15V, and switch the positive and negative electrodes every 15 minutes. If the water temperature in the closed space is below 50℃ after 15 minutes, switch back to alternating current heating to 70℃, and then switch back to direct current. The total running time of the second step is 1 hour. After the operation is completed, remove the motor and sealing ring, and let the inorganic membrane stand for 15 minutes.

[0045] Third step, place the inorganic membrane in a clean water environment and soak for 45 minutes, then rinse for 45 minutes, and backwash for 60 minutes.

[0046] Example 4

[0047] First step, perform regular forward and backwashing on the inorganic membrane contaminated by organic matter for a long time. The forward washing pressure is equal to the filtration pressure of the inorganic membrane, and the backwashing pressure is 3 times the forward washing pressure. The forward washing time is 40 minutes, and the backwashing time is 40 minutes. After washing, place the membrane in a 50℃ air environment for drying.

[0048] Second step, put the dried inorganic membrane into a closed container, open the vacuum valve, and draw the pressure in the container to -0.08 Mpa. Close the vacuum valve, open the ion liquid water valve, and pour 5% concentrated hydrochloric acid into the vacuum container until the liquid level is above the top end of the inorganic membrane. Open the vacuum valve, release the pressure, and soak for 60 min. Place electrodes on both sides of the inorganic membrane and press them with a sealing ring to form a closed space of electrode-ceramic membrane-electrode. The electrodes are water-impermeable electrode sheets with an area not less than that of the inorganic membrane, a titanium base, and a lead dioxide catalytic layer. The sealing ring is made of insulating rubber. Connect the electrodes to an alternating current with a voltage of 380 V, and the alternating charge is conducted to the ion liquid through the electrode surface, thereby generating an alternating current oscillation in the closed space containing the inorganic membrane to rapidly produce heat and heat the water to 70°C. Switch the alternating current to direct current with a voltage of 15 V, and switch the positive and negative electrodes every 15 min. If the water temperature in the closed space is below 50°C after 15 min, switch back to alternating current heating to 70°C, and then switch back to direct current. The total running time of the second step is 1 hour. After the operation is completed, remove the motor and sealing ring, and let the inorganic membrane stand for 15 min.

[0049] Third step, place the inorganic membrane in a clean water environment, soak for 45 min, then flush for 45 min, and backwash for 60 min.

[0050] Example 5

[0051] First step, perform regular forward flushing and backwashing on the inorganic membrane contaminated by long-term organic pollution. The forward flushing pressure is equal to the inorganic membrane filtration pressure, and the backwashing pressure is twice the forward flushing pressure. The forward flushing time is 30 min, and the backwashing time is 60 min. After flushing, place the membrane in a 40°C air environment for drying.

[0052] Second step, place the dried inorganic membrane in a closed container, open the vacuum valve, and reduce the pressure in the container to 0.15 Mpa. Close the vacuum valve, open the ion liquid water valve, and fill the container with 30 g / L sodium chloride solution until the liquid level reaches the top of the inorganic membrane. Open the vacuum valve, release the pressure, and soak for 30 min. Place electrodes on both sides of the inorganic membrane, which are boron-doped diamond electrodes, and press them firmly with a sealing ring to form a closed space of electrode-ceramic membrane-electrode. The electrodes are water-impermeable and have an area not less than that of the inorganic membrane. The electrodes are made of boron-doped diamond material. Connect the electrodes to an alternating current with a voltage of 220 V, and the alternating current charge is conducted to the ion liquid through the electrode surface, thereby generating rapid heat in the closed space containing the inorganic membrane, and heating the water to 60℃. Switch the alternating current to direct current with a voltage of 10 V, and switch the positive and negative electrodes every 10 min. If the water temperature in the closed space is below 50℃ after 10 min, switch back to alternating current heating to 60℃, and then switch back to direct current. The total running time of the second step is 1 hour. After the operation is completed, remove the motor and sealing ring, and let the inorganic membrane stand for 10 min.

[0053] Third step, place the inorganic membrane in a clean water environment and soak for 30 min, then rinse for 30 min, and backwash for 60 min.

[0054] Example 6

[0055] First step, perform regular forward and backwashing of the inorganic membrane contaminated by long-term organic pollution. The forward washing pressure is equal to the filtration pressure of the inorganic membrane, and the backwashing pressure is twice that of the forward washing pressure. The forward washing time is 30 min, and the backwashing time is 60 min. After washing, place the membrane in a 40℃ air environment for drying.

[0056] Second step, the dried inorganic membrane is placed in a closed container, the vacuum valve is opened, and the pressure in the container is extracted to -0.08 Mpa. The vacuum valve is closed, the ion liquid water valve is opened, and 30 g / L sodium chloride solution is poured into the vacuum container until the liquid level exceeds the top end of the inorganic membrane. The vacuum valve is opened, the pressure is released, and the soaking time is 30 min. An electrode pair is placed on both sides of the inorganic membrane, and the sealing ring is pressed to form a closed space of electrode-ceramic membrane-electrode. The electrode is a water-impermeable electrode sheet with an area not less than that of the inorganic membrane, the electrode substrate is a titanium substrate, and the electrode catalytic layer is ruthenium dioxide. The electrode is connected to an alternating current with a voltage of 220 V, and the alternating current charge is conducted to the ion liquid through the electrode surface, thereby causing the closed space containing the inorganic membrane to generate alternating current oscillation and rapid heat generation, and the water temperature is heated to 60°C. The alternating current is switched to direct current with a voltage of 10 V, and the positive and negative electrodes are switched every 10 min. If the water temperature in the closed space is lower than 50°C after 10 min, the alternating current heating is switched back to 60°C, and then the direct current is switched back. The total running time of the second step is 1 hour. After the operation is completed, the motor and the sealing ring are removed, and the inorganic membrane is left to stand for 10 min.

[0057] Third step, the inorganic membrane is placed in a clean water environment and soaked for 30 min, then washed for 30 min, and backwashed for 60 min.

[0058] Example 7

[0059] The inorganic membrane has a pure water flux of 200 L / m 2 / h, and the initial humic acid retention rate is 95%. After running for 3 years, the flux attenuation is 23% of the pure water flux

[0060] After the conventional cleaning according to step one of example 1, the flux is 25% of the pure water flux, indicating that there are a large number of serious pore blockages in the inorganic membrane, and conventional washing cannot restore them.

[0061] The inorganic membrane is treated according to the operation method of example 1, and the second step of electrochemical self-heating pressure washing is performed, and the third step of conventional washing is performed. The membrane flux is restored to 92% of the pure water flux, indicating that a large number of blocked organic matter is removed, and the humic acid retention rate after restoration is 94.2%.

[0062] Comparative example 1 (conventional chemical washing compared with the present application)

[0063] The inorganic membrane has a pure water flux of 200 L / m 2 / h, and the initial humic acid retention rate is 95%. After running for 3 years, the flux attenuation is 23% of the pure water flux

[0064] The inorganic membrane has a pure water flux of 200 L / m 2 / h, flux attenuation is 23.3% of pure water flux. After regular cleaning, 5% (about 50g / L) hypochlorite cleaning, and 6h soaking, the flux is recovered to 68% of pure water flux;

[0065] The inorganic membrane has a pure water flux of 200 L / m 2 / h, flux attenuation is 23% of pure water flux. According to the operation method of example 1, the inorganic membrane is processed, and step two is electrochemical self-heating pressurization cleaning, and the third step is regular cleaning, and the membrane flux is recovered to 92% of pure water flux.

[0066] Comparative example 2 (AC, DC comparison)

[0067] The inorganic membrane has a pure water flux of 200 L / m 2 / h, flux attenuation is 20.4% of pure water flux. According to the parameters of example 1, cleaning is carried out, but the AC step is cancelled, and only the DC step is used. After cleaning, the flux is recovered to 72.3% of pure water flux.

[0068] The inorganic membrane has a pure water flux of 200 L / m 2 / h, flux attenuation is 21.3% of pure water flux. According to the parameters of example 1, cleaning is carried out, including AC and DC steps. After cleaning, the flux is recovered to 91% of pure water flux.

[0069] Comparative example 3 (temperature influence)

[0070] The contaminated inorganic membrane is cleaned according to the parameters of example 1. By adjusting the AC voltage or time, the temperature in the sealed space is controlled, and the reaction temperature is controlled to be 45℃, 50℃, 60℃, 70℃, 80℃, and 90℃, respectively. Under different temperatures, the flux recovery rate of the inorganic membrane is 76%, 79%, 89%, 91%, 94%, and 94% of pure water flux, respectively. It can be seen that the reaction temperature has a great influence on the cleaning effect of the membrane. When the temperature is lower than 60℃, the flux recovery rate of the membrane cleaning is difficult to reach 80%. When the temperature is in the range of 60-80℃, the flux recovery rate is close to or even exceeds 90%. When the temperature exceeds 80℃, the improvement of the flux recovery rate is limited. Generally, the temperature is controlled to be not more than 100℃.

[0071] The present application is not limited to the specific technical solutions described in the above examples. Any technical solution formed by equivalent replacement is within the scope of protection required by the present application.

Claims

1. An electrochemical self-thermal pressurized inorganic membrane high-efficiency cleaning method, characterized in that The method comprises pre-flushing, vacuum inductive ion liquid infiltration of inorganic membrane, closed electrochemical cleaning and post-flushing, and the specific steps are as follows: (1) a pre-flushing step, that is, performing normal forward flushing and back flushing on the inorganic membrane polluted by long-term organic pollution, the forward flushing pressure is equal to the filtration pressure of the inorganic membrane, and the back flushing pressure is 2-4 times the forward flushing pressure; the forward flushing time is 30-90 min, and the back flushing time is 60-120 min; after flushing, the membrane is dried in air or a heated environment; (2) a vacuum inductive ion liquid infiltration step of the inorganic membrane, that is, placing the dried inorganic membrane in a closed container, opening a vacuum valve to draw the pressure in the container to-0.08 MPa or lower, closing the vacuum valve, opening an ion liquid inlet valve, and pouring an inorganic electrolyte solution containing chloride ions into the vacuum container until the liquid level is higher than the top end of the inorganic membrane, opening the vacuum valve to release the pressure, and soaking for 30-60 min; a closed electrochemical cleaning step, that is, placing electrode pairs on both sides of the inorganic membrane and compacting the electrode pairs through a sealing ring to form a closed space of electrode-ceramic membrane-electrode; the electrode is a water-impermeable electrode sheet, and the electrode area is not less than the area of the inorganic membrane, in the closed electrochemical cleaning step, the electrodes are connected to alternating current, the alternating voltage is 220-380 V, and the alternating current is conducted to the ion liquid through the electrode surface, so that the closed space containing the inorganic membrane generates alternating current oscillation to rapidly generate heat, and the water temperature is heated to 60-80 DEG C; the alternating current is switched to direct current, the direct voltage is 5-30 V, the positive and negative electrodes are switched every 10-20 min, when the water temperature in the closed space is lower than 50 DEG C at the end of a cycle of the direct current, the alternating current is switched back to heat to the required temperature, and then the direct current is switched back; the total running time of the direct current is not more than 2 hours; after the running is completed, the electrodes and the sealing ring are removed, and the inorganic membrane is placed for 5-15 min; (3) a post-flushing step, that is, placing the inorganic membrane in a clean water environment, soaking for 20-60 min, then forward flushing for 20-60 min, and back flushing for 20-60 min.

2. The electrochemical self-heating pressurized inorganic membrane high- efficiency cleaning method according to claim 1, characterized in that: The inorganic electrolyte solution containing chloride ions is sodium chloride, potassium chloride or dilute hydrochloric acid, and the concentration is 10-50 g / L.

3. The electrochemical self-heat pressurized inorganic membrane high- efficiency cleaning method according to claim 1, characterized in that: The electrode base is a titanium corrosion-resistant base.

4. The electrochemical self-heating pressurized inorganic membrane high- efficiency cleaning method of claim 1, wherein: The catalytic layer of the electrode is a ruthenium, lead or tin electrochemically active oxide.

5. The electrochemical self-heat pressurized inorganic membrane high- efficiency cleaning method according to claim 1, characterized in that: The sealing ring is an insulating rubber organic polymer.

6. The electrochemical self-heat pressurized inorganic membrane high- efficiency cleaning method according to claim 1, characterized in that: The specific steps are as follows: (1) performing normal forward flushing and back flushing on the inorganic membrane polluted by long-term organic pollution, the forward flushing pressure is equal to the filtration pressure of the inorganic membrane, and the back flushing pressure is 2 times the forward flushing pressure; the forward flushing time is 30 min, and the back flushing time is 60 min; after flushing, the membrane is dried in a 40 DEG C air environment; (2) Put the dried inorganic membrane into a closed container, open the vacuum valve, and draw the pressure in the container to -0.08 Mpa or lower; close the vacuum valve, open the ion liquid water valve, and pour 30 g / L sodium chloride solution into the vacuum container until the liquid level is above the top end of the inorganic membrane; open the vacuum valve, release the pressure, and soak for 30 min; place an electrode pair on both sides of the inorganic membrane, the electrode material is titanium substrate ruthenium oxide coated electrode, and the electrode is compacted by a sealing ring to form a closed space of electrode-ceramic membrane-electrode; the electrode is a water-impermeable electrode sheet, the electrode area is not less than the inorganic membrane area, the electrode substrate can be a titanium substrate, and the electrode catalytic layer is lead dioxide; the sealing ring is made of insulating rubber; connect the electrodes to alternating current, the alternating voltage is 220 V, and the alternating charge is conducted to the ion liquid through the electrode surface, thereby causing the closed space containing the inorganic membrane to generate alternating current oscillation and rapid heat generation, and the water temperature is heated to 70°C; switch the alternating current to direct current, the direct current voltage is 10 V, and the positive and negative electrodes are switched every 10 min; if the water temperature in the closed space is lower than 50°C after 10 min, switch back to alternating current heating to 70°C, and then switch back to direct current; the total running time of step (2) is 1 hour; after the running is completed, remove the electrodes and sealing ring, and let the inorganic membrane stand for 10 min; (3) Put the inorganic membrane in a clean water environment, soak for 30 min, then wash for 30 min, and backwash for 60 min.

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