Multistage response type targeted membrane cleaning agent as well as preparation method and application thereof

Abstract

The invention discloses a multistage response type targeted membrane cleaning agent as well as a preparation method and application thereof, and belongs to the technical field of membrane separation in the water treatment industry. The multistage response type targeted membrane cleaning agent comprises active ingredients, a carrier material, a membrane passivator and a surfactant, the active ingredients comprise metal ion chelating microspheres, oxidized-dispersed core-shell nanoparticles and a zwitter-ion charge dynamic regulator, the carrier material is three-dimensional network gel embedded with the active ingredients, and the membrane passivator is a zwitter-ion charge dynamic regulator. The membrane passivator is a functionalized silane coupling agent, a silanol group of the functionalized silane coupling agent can react with a hydroxyl group on the surface of the membrane to form a Si-O-Si net structure, and the surfactant is an anionic surfactant; the multi-level response type targeted membrane cleaning agent can specifically recognize a high-pollution area on the surface of a membrane, the effect of spatio-temporal controlled release of active ingredients in a graded response mode is achieved, a Si-O-Si passivation layer is formed on the surface of the membrane, the adhesion energy of subsequent pollutants is reduced, and the multi-level response type targeted membrane cleaning agent has a good cleaning effect on an immersed membrane assembly.

Description

Technical Field

[0001] The present invention belongs to the field of membrane separation technology in the water treatment industry, and specifically relates to a multi-stage responsive targeted membrane cleaning agent and a preparation method and application thereof. Background Art

[0002] Membrane separation technology is a physical separation method based on the principle of selective permeation. It uses membrane materials with specific pore sizes or chemical properties to achieve efficient separation of different components in a solution (such as ions, molecules, colloids, etc.). Its core advantages are that it does not require phase change, has low energy consumption, and is easy to operate. Therefore, it is widely used in seawater desalination, industrial wastewater treatment, drinking water purification, biomedical separation and other fields. In recent years, with the intensification of global water shortage problems and stricter environmental protection regulations, the position of membrane separation technology in the water treatment field has become increasingly important. For example, reverse osmosis (RO) technology has become the mainstream process for seawater desalination, while ultrafiltration (UF) and microfiltration (MF) technologies are widely used in industrial wastewater reuse and drinking water pretreatment. In addition, membrane technology is also used in high-value-added fields such as hydrogen water preparation, food processing, and ultrapure water production in the electronics industry.

[0003] As the core separation unit in the fields of seawater desalination, industrial wastewater reuse and hydrogen water preparation, the water treatment membrane system's stable permeation flux and long-term anti-pollution performance directly determine the system's energy efficiency and economy. However, during operation, the membrane surface will inevitably be enriched with a complex pollutant layer of colloidal particles, microbial metabolites (EPS) and inorganic salt crystals, which will cause membrane fouling. Membrane fouling refers to the deposition of pollutants (such as colloidal particles, microbial metabolites, inorganic salt crystals, etc.) on the membrane surface or in the pores during operation, forming a dense fouling layer, resulting in a decrease in membrane flux, an increase in operating pressure, an increase in energy consumption, and even irreversible damage to the membrane material. According to statistics, the flux attenuation caused by pollution during membrane system operation can reach 30%-60%, and the cleaning frequency increases to 2-3 times a week, which directly increases operation and maintenance costs.

[0004] Chemical cleaning is currently the most common method for addressing membrane fouling. Chemical cleaning agents break down the interfacial bonds between contaminants, causing them to disintegrate, thereby removing the fouling layer and regenerating membrane function. However, their composition and mechanism of action must meet three conflicting requirements: efficiently removing multiple types of contaminants, avoiding membrane material damage, and suppressing secondary contamination.

[0005] However, existing cleaning technologies have the following key drawbacks:

[0006] (1) Functional singleness limitation: Quaternary ammonium salt fungicides are completely ineffective against silicate pollution, resulting in an increase in cleaning frequency to 2-3 times a week; and chelating agents represented by ethylenediaminetetraacetic acid (EDTA), such as the Chinese patent with publication number CN112877151A and application date of April 16, 2021, discloses a high-efficiency alkaline cleaning agent for leachate pollutants and its use. Although it can remove inorganic and organic pollution in leachate, including heavy metal pollution and a lot of humus pollution, it cannot decompose extracellular polymers such as β-1,3-glucan in biofilms.

[0007] (2) Material compatibility defects: Although strong acids such as hydrochloric acid and nitric acid can dissolve metal oxide dirt, for example, the Chinese patent with publication number CN112999882A and application date of April 16, 2021 discloses a high-efficiency acid cleaning agent for landfill leachate pollutants and its use, it may cause the crystallinity of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) and other materials to decrease, resulting in a decrease in mechanical strength by 30-

[0008] 50%; cleaning with complex acids such as nitric acid may even cause the epoxy resin in the hollow fiber membrane potting part to swell and crack.

[0009] (3) Chemical residue risk: Residual active chlorine after sodium hypochlorite (NaClO) oxidation cleaning will continue to attack the sulfonic acid groups of the polyethersulfone (PES) membrane, causing irreversible membrane pore collapse, reducing the surface porosity from 35% to 22%, and catalyzing pitting corrosion of the metal support of the membrane component, shortening the system life by 30-50%.

[0010] With the water treatment industry's increasing demands on membrane equipment performance for various types of non-fresh water, membrane modules must withstand high salinity, high biological activity, and intermittent operation. This further highlights the limitations of traditional cleaning agents or compound cleaning agents. There is an urgent need to develop a targeted cleaning agent system that combines multiple mechanisms and is highly compatible with materials. This system can improve pollutant removal efficiency while also addressing membrane material protection and environmental requirements. This system can achieve deep removal of membrane pollutants and protect membrane integrity, thereby enhancing its industrial feasibility and applicability in complex scenarios. Summary of the Invention

[0011] In order to solve the problems existing in the prior art, the present invention discloses a multi-stage responsive targeted membrane cleaning agent and its preparation method and application, which can specifically identify highly polluted areas on the membrane surface, achieve the effect of graded responsive spatiotemporal controlled release of active ingredients, reduce the subsequent adhesion energy of pollutants, and have a good cleaning effect on submerged membrane components.

[0012] The technical solutions of the present invention are as follows:

[0013] One of the purposes of the present invention is to provide a multi-stage responsive targeted membrane cleaning agent, a multi-stage responsive targeted membrane cleaning agent, characterized in that the multi-stage responsive targeted membrane cleaning agent comprises 5-20% active ingredient, 30-50% carrier material, 0.05-5% membrane passivator, 5-15% anionic surfactant and deionized water;

[0014] The active ingredients include 1-5% metal ion chelating microspheres, 2-8% oxidized-dispersed core-shell nanoparticles, and 2-7% zwitterionic charge dynamic regulators;

[0015] The metal ion chelating microspheres are cross-linked microspheres composed of ethylenediaminetetraacetic acid (EDTA) derivatives and sulfonated polystyrene copolymers, encapsulated in the β-cyclodextrin cavity. The oxidative-dispersive core-shell nanoparticles are cored with peroxysulfate (PMS) and a sodium hypochlorite (NaClO) sustained-release agent (SLS) as the shell. The zwitterionic charge dynamic regulator is a pH-responsive amphoteric copolymer.

[0016] The carrier material is a three-dimensional network thermosensitive hydrogel embedded with active ingredients;

[0017] The film passivating agent is a functionalized silane coupling agent;

[0018] The anionic surfactant is at least one of sodium alkyl sulfonate, sodium alkyl aryl sulfonate and sodium alkyl sulfate.

[0019] Furthermore, the particle size of the metal ion chelating microspheres is 270-370 nm; the ethylenediaminetetraacetic acid (EDTA) derivative is at least one of EDTA sodium salt, EDTA sodium iron, EDTA esterified derivative, methylglycine diacetic acid (MGDA), and glutamic acid diacetic acid tetrasodium (GLDA).

[0020] Furthermore, the particle size of the oxidized-dispersed core-shell nanoparticles is controlled between 10-50 nm.

[0021] Furthermore, the zwitterionic charge dynamic regulator is at least one of polyamino acid derivatives, betaines, modified natural zwitterionic polymers, and synthetic zwitterionic polymers.

[0022] Furthermore, the three-dimensional network temperature-sensitive hydrogel is N-isopropylacrylamide-based gel or Pluronic F127 hydrogel.

[0023] Furthermore, the Pluronic F127 hydrogel is an amphiphilic triblock copolymer that self-assembles into micelles with a hydrophobic cavity and a hydrophilic outer wall in water, and the hydrophobic cavity can efficiently load active ingredients.

[0024] Furthermore, the functionalized silane coupling agent is at least one or more of aminosilane, epoxysilane, methacryloxysilane, long-chain alkylsilane, fluorosilane, etc.

[0025] A second object of the present invention is to provide a method for preparing a multi-stage responsive targeted membrane cleaning agent, comprising the following steps:

[0026] S1. Dissolve ethylenediaminetetraacetic acid (EDTA) derivatives and sulfonated polystyrene copolymer in deionized water, add β-cyclodextrin for ultrasonic embedding, and spray dry to obtain metal ion chelating microspheres. The mass ratio of ethylenediaminetetraacetic acid (EDTA) derivatives to sulfonated polystyrene copolymer is 13:7, and the mass ratio of β-cyclodextrin to sulfonated polystyrene copolymer is 5:4.

[0027] S2, mixing 2M ammonium sulfate solution and 0.1M ferrous metal solution in a volume ratio of 1:3 to generate a transition metal oxide-supported peroxysulfate magnetic core through a hydrothermal reaction;

[0028] S3. Coating the surface of the magnetic core obtained in S2 with an inorganic / hypochlorite composite shell layer by a sol-gel method under alkaline conditions, adjusting the molar ratio of the precursor ethyl orthosilicate to sodium hypochlorite to 1:2-1:5, the reaction temperature to 20-50°C, and standing and aging for 12-36 hours to form a core-shell structure with oxidative slow-release function;

[0029] S4, free radical copolymerizing the carboxylic acid-containing monomer and the sulfobetaine-type monomer in the presence of an initiator, adjusting the pH of the resulting copolymer to neutral and freeze-drying the resulting copolymer to obtain a zwitterionic charge dynamic regulator;

[0030] S5, dissolving the thermosensitive hydrogel in deionized water to form a sol / micelle system, adding the metal ion chelating microspheres prepared in S1 and the oxidized-dispersed core-shell nanoparticles prepared in S3, adding glycidyl methacrylate (GMA) as a crosslinking agent after ultrasonic dispersion, and standing at low temperature for crosslinking to form a three-dimensional network thermosensitive hydrogel loaded with active ingredients;

[0031] S6, a silane compound containing epoxy groups and long-chain alkyl groups is mixed, hydrolyzed and activated in an acidic alcohol-water system, and a film passivating agent containing active siloxane groups at the end is formed after the solvent is removed;

[0032] S7, compounding an anionic surfactant and an auxiliary emulsifier, sodium dioctyl sulfosuccinate AOT, in a mass ratio of 3:2, adding disodium ethylenediaminetetraacetic acid EDTA-Na2 as a complexing stabilizer, and then subjecting the mixture to high shear emulsification and high-pressure homogenization to form a micellar dispersion with a particle size distribution of less than 100 nm, thereby obtaining an anionic surfactant system;

[0033] S8, crushing the three-dimensional network temperature-sensitive hydrogel obtained in S5 into micron-sized particles, mixing the particles with the anionic surfactant system formed in S7, adding the zwitterionic charge dynamic regulator prepared in S4 and the membrane passivator prepared in S6 stepwise, and stirring thoroughly to form a cleaning agent precursor having a multiphase structure;

[0034] S9. A freeze-drying-rehydration swelling process is used to quickly freeze the cleaning agent precursor to form directional crystalline ordered channels, and the precursor is vacuum dried and dehydrated at low temperature to retain the nanoscale pore structure. The remaining deionized water in the formula is added and the mixture is swelled at 25°C to a viscosity of 1000-1500 mPa·s to obtain the multi-stage responsive targeted membrane cleaning agent.

[0035] Furthermore, the S1 is ultrasonically embedded at 40 kHz for 30 minutes.

[0036] Furthermore, the particle size of the microspheres obtained by spray drying in S1 is 270-370 nm.

[0037] Furthermore, the hydrothermal reaction conditions in S2 are 120-180° C., 6-24 h.

[0038] Furthermore, the thickness of the composite shell in S3 is 9-20 nm.

[0039] Furthermore, the copolymerization reaction system in S4 is protected by inert gas, the temperature is controlled at 60-70° C., and the reaction time is 10 h.

[0040] Furthermore, the amount of the cross-linking agent added in S5 is 0.1% to 5% of the total mass of the system.

[0041] Furthermore, the hydrolysis pH in S6 is controlled at 3-5 and the temperature is controlled at 50-70°C.

[0042] Furthermore, in the S9, the nanoporosity is maintained to be not less than 60%.

[0043] A third object of the present invention is to provide a multi-stage responsive targeted membrane cleaning agent for use in cleaning submerged membrane modules.

[0044] Further, the cleaning operation is as follows:

[0045] The multi-stage responsive targeted membrane cleaning agent in emulsion state is injected into the membrane module circulation system at 0.1-0.5wt%. The water environment is in a weakly acidic state, the temperature is maintained at 35-40°C, the circulation flow rate is 1-2m / s, and the total cleaning time is ≤6 hours.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. The present invention breaks through the limitations of traditional membrane chemical cleaning agents with single functions and static random diffusion by designing a multi-stage responsive targeted membrane cleaning agent. Its core innovation lies in the construction of a specific triggering and spatiotemporal controlled release mechanism. By forming an active carrier and a permeation channel through a thermosensitive three-dimensional network hydrogel, the metal ion chelating microsphere component (80% release within 1 hour), the oxidized-dispersed core-shell nanoparticle component (1-3 hours sustained release), and the zwitterion dynamic regulator component (3-5 hours responsive release) are released in stages and with precise timing control, achieving the sequential synergy of salt scale complexation, biofilm degradation, and residual particle adsorption. The specific graded release kinetics are as follows:

[0048] The first stage (0-2h): The metal ion chelating microspheres are slowly released in the contaminated area on the membrane surface, and complex with the salt scale ions to gradually disintegrate the salt crystal structure;

[0049] Phase 2 (2-12h): Metal ion chelating microspheres and oxidation-dispersion composite particles work synergistically to decompose inorganic sediments and biofilms;

[0050] The third stage (>12h): The zwitterionic dynamic regulator achieves deep removal of residual particles through charge adsorption.

[0051] 2. The multi-stage responsive targeted membrane cleaning agent of the present invention is designed with a targeted chelation-oxidation dual-cycle mechanism, in which the metal ion chelating microsphere component specifically recognizes Ca 2 + (released when the concentration threshold is >50mg / L), preferentially complexing scaling ions (Ca 2+ / Mg 2+ ), achieving crystal skeleton disintegration, with a complexation efficiency of up to 98.7%. The oxidized-dispersed core-shell nanoparticles PMS / NaClO trigger the Fenton reaction to produce reactive oxygen species (·OH, SO4·-) after contacting organic matter, destroying the extracellular polysaccharide matrix in the biofilm; the outer layer NaClO precisely oxidizes the lipid layer of the microbial cell wall, and the two-phase synergy strips the biofouling, with a biofilm degradation rate of >90%; in addition, the zwitterionic dynamic regulator can form a pH-responsive charge layer on the membrane surface. When the biofilm metabolism causes local alkalinization resulting in an environmental pH greater than 7, the polymer becomes positively charged and electrostatically combines with the negatively charged organic colloid, further enhancing the physical stripping efficiency.

[0052] 3. The multi-stage responsive targeted membrane cleaning agent of the present invention can not only deeply remove membrane pollutants, but also achieve subsequent dynamic interface protection. The anionic surfactant quickly spreads and penetrates the gaps between pollutants, reducing the surface tension to 25-30mN / m, breaking up the colloidal stacking structure, and the silanol groups of the membrane passivator react with the hydroxyl groups on the membrane surface to form a Si-O-Si network structure. After cleaning, it remains on the membrane surface to form a silicon-oxygen network layer with a hydrophobic angle of >110°, reducing the subsequent adsorption of pollutants by 40%. In addition, the oxidation-dispersed core-shell nanoparticles can also optimize the hardness to a Mohs hardness of 1.2, reducing the scratch density on the membrane surface by 70%.

[0053] 4. The multi-stage responsive targeted membrane cleaning agent prepared by the present invention shows an ideal cleaning effect, good operability and economy in engineering applications, especially in cleaning submerged membrane modules. The cleaning efficiency for CaSO4 scale and mixed biological pollution with a thickness of >50μm can reach 92.1%, which is 35% higher than the traditional EDTA+SDS method, and can restore the membrane contact angle to 98% of the initial value. In addition, the multi-stage responsive targeted membrane cleaning agent replaces the multi-step agent switching with a single cleaning agent, the cleaning time is ≤6 hours, the energy consumption is reduced by 20%, and it is suitable for the high salinity, high biological activity and intermittent operation conditions of submerged membrane modules. It can be expanded to fields such as seawater desalination, industrial wastewater reuse and hydrogen water preparation, and the comprehensive operation and maintenance costs are reduced by more than 40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the structure of the oxidized-dispersed core-shell nanoparticles in the active ingredient of the multi-stage responsive targeted membrane cleaning agent of the present invention, 1-NaClO shell; 2-PMS core;

[0055] Figure 2 This is the kinetic curve of the staged release of active ingredients from the three-dimensional network temperature-sensitive hydrogel Pluronic F127 in the multi-stage responsive targeted membrane cleaning agent carrier material of the present invention. DETAILED DESCRIPTION

[0056] The present invention will be further described below in conjunction with preferred embodiments. The embodiments are provided only to illustrate the present invention, but not to limit the scope of the present invention.

[0057] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0058] The quantitative tests in the following examples were performed three times independently and the results were averaged.

[0059] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0060] Example 1

[0061] This embodiment provides a method for preparing a multi-stage responsive targeted membrane cleaning agent, comprising the following steps:

[0062] S1. Dissolve 5.2 g of EDTA-Na and 2.8 g of sulfonated polystyrene copolymer in 100 mL of deionized water, add 3.5 g of β-cyclodextrin, and embed by 40 kHz ultrasound for 30 min. Spray dry to obtain metal ion chelated microspheres.

[0063] S2, 2M ammonium sulfate solution and 0.1MFe 2+ The solutions were mixed at v / v = 1:3 and the Fe3O4@PMS magnetic core was generated by hydrothermal reaction at 120 °C for 6 h;

[0064] S3. Hydrolyze 3 g of tetraethyl orthosilicate (TEOS) and 1.5 g of sodium hypochlorite (NaClO) at pH 9 and 35°C, and allow to stand for 24 h to deposit a 10 nm thick SiO2 / NaClO composite shell on the surface of Fe3O4 to obtain Fe3O4@PMS@SiO2 / NaClO core-shell nanoparticles.

[0065] S4. Dissolve 3 g of carboxymethyl chitosan (CMCS) in deionized water, add 8 g of sodium 3-chloro-2-hydroxypropanesulfonate, and react with stirring at 60°C for 10 h; add 0.5 mL of epichlorohydrin and continue the reaction for 2 h; adjust the pH to 7.0, purify by ultrafiltration and centrifugation (10 kDa), and lyophilize to obtain sulfonated carboxymethyl chitosan (S-CMCS).

[0066] S5, dissolve 35g of Pluronic F127 in 100mL of deionized water and stir at 45°C until completely dissolved to form a transparent micelle system; add 9g of Fe3O4@PMS@SiO2 / NaClO core-shell nanoparticles prepared in S3 and 4.5g of metal ion chelating microspheres prepared in S1, and disperse them ultrasonically at 200W for 30min; inject 2mL of glycidyl methacrylate (GMA) as a crosslinker, and let it stand at 4°C for 12h to form a three-dimensional network thermosensitive hydrogel loaded with active ingredients;

[0067] S6. 5 g of epoxysilane (APTES) and 3 g of long-chain alkylsilane (ODTES) were mixed at a ratio of 3:1 and dissolved in an ethanol / water solution (V / V = 9:1); the solution was adjusted to pH 4.5 with 0.1 M HCl and hydrolyzed at 60° C. for 30 min to generate -Si-O-CHCH active groups; the ethanol was removed by rotary evaporation to obtain a modified silane coupling agent concentrate with a final concentration of 20 wt%;

[0068] S7. Mix 15 g of sodium dodecyl sulfate (SDS) and 10 g of sodium dioctyl sulfosuccinate (AOT), dissolve in 50 mL of 40° C. deionized water; add 0.5% disodium ethylenediaminetetraacetic acid (EDTA-Na2) as a complexing stabilizer, and emulsify at 1500 rpm for 10 min; pass through a high-pressure homogenizer at 50 MPa for three cycles to obtain a homogenized surfactant micelle dispersion;

[0069] S8, crush 40g of the hydrogel carrier prepared in S5 into 350μm particles and mix with 25g of the surfactant compound solution in S7; add 0.1g of the silane coupling agent activation solution in S6 dropwise and stir, and simultaneously add 7g of the zwitterionic charge regulator powder in S4 and stir thoroughly to form a cleaning agent precursor;

[0070] S9, using freeze drying-rehydration process, quick freezing the cleaning agent precursor at -80℃ for 4 hours to form ice crystal template directional channels; and dehydrating at -50℃ / 10Pa low temperature vacuum drying for 24 hours to retain the nano-scale pore structure;

[0071] S10. Add the remaining amount of deionized water to the mixture at 25° C. and swell until the viscosity reaches 1250 mPa·s, thereby preparing a multi-level responsive targeted membrane cleaning agent.

[0072] Example 2

[0073] This embodiment provides a multi-stage responsive targeted membrane cleaning agent, the preparation method of which includes the following steps:

[0074] S1. Dissolve 5.2 g of EDTA-Na2 and 2.8 g of sulfonated polystyrene copolymer in 100 mL of deionized water, add 3.5 g of β-cyclodextrin, and embed by 40 kHz ultrasound for 30 min. Spray dry to obtain metal ion chelated microspheres.

[0075] S2, 2M ammonium sulfate solution and 0.1MFe 2+ The solutions were mixed at v / v = 1:3 and the Fe3O4@PMS magnetic core was generated by hydrothermal reaction at 150 °C for 15 h;

[0076] S3, hydrolyzing tetraethyl orthosilicate (TEOS) and sodium hypochlorite (NaClO) at pH 9 and 20°C, and allowing to stand for 36 h to deposit a 20 nm thick SiO2 / NaClO composite shell on the Fe3O4 surface to obtain Fe3O4@PMS@SiO2 / NaClO core-shell nanoparticles;

[0077] S4. Dissolve 10 g of acrylic acid and 15 g of [2-(methacryloyloxy)ethyl]dimethyl(3-sulfonic acid propyl)ammonium hydroxide (SBMA) in 200 mL of anhydrous ethanol, and add 0.1% azobisisobutyronitrile (AIBN) as an initiator; react at 65° C. under nitrogen for 10 h to obtain a poly(AA-SBMA) binary copolymer; add 0.5 M NaOH dropwise to the copolymer solution to adjust the pH to 7.0, and freeze-dry to obtain a white flocculent zwitterionic charge modifier powder;

[0078] S5, dissolve 30g of Pluronic F127 in 100mL of deionized water, stir at 45℃ until completely dissolved to form a transparent micelle system; add 10g of Fe3O4@PMS@SiO2 / NaClO core-shell nanoparticles prepared in S3 and 5g of metal ion chelated microspheres prepared in S1, and disperse them ultrasonically at 200W for 30min; inject 2mL of glycidyl methacrylate (GMA) as a crosslinker, and let it stand at 4℃ for 12h to form a three-dimensional network thermosensitive hydrogel loaded with active ingredients;

[0079] S6. Dissolve 5 g of commercially available phenyltriethoxysilane KH-162 in an ethanol-water mixture (v / v=2:1) ​​to obtain a silane coupling agent solution with a final concentration of 15 wt%;

[0080] S7. Mix 15 g of sodium dodecyl sulfate (SDS) and 10 g of sodium dioctyl sulfosuccinate (AOT), dissolve in 50 mL of 40° C. deionized water; add 0.5% disodium ethylenediaminetetraacetic acid (EDTA-Na2) as a complexing stabilizer, and emulsify at 1500 rpm for 10 min; pass through a high-pressure homogenizer at 50 MPa for three cycles to obtain a homogenized surfactant micelle dispersion;

[0081] S8, crush 40g of the hydrogel carrier prepared in S5 into 200μm particles and mix with 25g of the surfactant compound solution in S7; add 0.1g of the silane coupling agent activation solution in S6 dropwise and stir, and simultaneously add 7g of the zwitterionic charge regulator powder in S4 and stir thoroughly to form a cleaning agent precursor;

[0082] S9, using freeze drying-rehydration process, quick freezing the cleaning agent precursor at -80℃ for 4 hours to form ice crystal template directional channels; and dehydrating at -50℃ / 10Pa low temperature vacuum drying for 24 hours to retain the nano-scale pore structure;

[0083] S10. Add the remaining amount of deionized water in the formula and swell at 25° C. until the viscosity reaches 1000 mPa·s, thereby preparing a multi-level responsive targeted membrane cleaning agent.

[0084] Example 3

[0085] This embodiment provides a multi-stage responsive targeted membrane cleaning agent, the preparation method of which includes the following steps:

[0086] S1. Dissolve 5.2 g of EDTA-Na and 2.8 g of sulfonated polystyrene copolymer in 100 mL of deionized water, add 3.5 g of β-cyclodextrin, and embed by 40 kHz ultrasound for 30 min. Spray dry to obtain metal ion chelated microspheres.

[0087] S2, 2M ammonium sulfate solution and 0.1MFe 2+ The solutions were mixed at v / v = 1:3 and the Fe3O4@PMS magnetic core was generated by hydrothermal reaction at 180 °C for 24 h;

[0088] S3, hydrolyzing tetraethyl orthosilicate (TEOS) and sodium hypochlorite (NaClO) at pH 9 and 50°C, and allowing to stand for 12 h to deposit a 50 nm thick SiO2 / NaClO composite shell on the surface of Fe3O4 to obtain Fe3O4@PMS@SiO2 / NaClO core-shell nanoparticles;

[0089] S4, 10g polysuccinimide PSI (Mw = 5 × 10 4 Da) was dissolved in DMSO, and 15 g of sodium 3-mercaptopropanesulfonate (MPS) and 8 g of 2-dimethylaminoethylthiol (DMAET) were added sequentially at 50° C. in a molar ratio of 1:1:1. The reaction was carried out for 24 h, and the sulfonic acid / tertiary amine zwitterionic side chains were grafted onto the sulfonate / tertiary amine zwitterionic side chains using mercapto-succinimide ring-opening. Dithiothreitol (DTT) (mercapto:DTT = 5:1) was added to initiate dynamic disulfide crosslinking between the side chain sulfhydryl groups. Unreacted monomers and solvent were removed by dialysis, and the mixture was freeze-dried to obtain a sulfonic acid-amine zwitterionic polymer.

[0090] S5, dissolve 38g of Mebiol gel hydrogel in 100mL of deionized water and stir at 45°C until completely dissolved to form a transparent micelle system; add 10g of FeO@PMS@SiO / NaClO core-shell nanoparticles prepared in S3 and 5g of metal ion chelating microspheres prepared in S1, and disperse them ultrasonically at 200W for 30min; inject 2mL of glycidyl methacrylate (GMA) as a crosslinker, and let it stand at 4°C for 12h to form a three-dimensional network thermosensitive hydrogel loaded with active ingredients;

[0091] S6. Dissolve 3 g of commercially available 1H,1H,2H,2H-perfluorodeoxysilane in an ethanol-water mixture (v / v=2:1) ​​to obtain a silane coupling agent solution with a final concentration of 18 wt%;

[0092] S7. Mix 15 g of sodium dodecyl sulfate (SDS) and 10 g of sodium dioctyl sulfosuccinate (AOT), dissolve in 50 mL of 40° C. deionized water; add 0.5% disodium ethylenediaminetetraacetic acid (EDTA-Na2) as a complexing stabilizer, and emulsify at 1500 rpm for 10 min; pass through a high-pressure homogenizer at 50 MPa for three cycles to obtain a homogenized surfactant micelle dispersion;

[0093] S8, crush 42g of the hydrogel carrier prepared in S5 into 500μm particles and mix with 23g of the surfactant compound solution in S7; add 0.1g of the silane coupling agent activation solution in S6 dropwise and stir, and simultaneously add 5g of the zwitterionic charge regulator powder in S4 and stir thoroughly to form a cleaning agent precursor;

[0094] S9, using freeze drying-rehydration process, quick freezing the cleaning agent precursor at -80℃ for 4 hours to form ice crystal template directional channels; and dehydrating at -50℃ / 10Pa low temperature vacuum drying for 24 hours to retain the nano-scale pore structure;

[0095] S10. Add the remaining amount of deionized water in the formula and swell at 25° C. until the viscosity reaches 1500 mPa·s, thereby preparing a multi-level responsive targeted membrane cleaning agent.

[0096] Performance Testing

[0097] 1. Scaling ion complexation test

[0098] The scaling ion complexation test of the multi-stage responsive targeted membrane cleaning agent prepared in Example 1 was carried out. 0.5 wt% of the targeted membrane cleaning agent was added to a solution containing 20 mg / L CaCl, and the Ca content in the solution was tracked by element detection methods such as ICP-MS or ICP-OES. 2+ Content changes.

[0099] The test results show that the metal ion chelating microspheres of the multi-level responsive targeted membrane cleaning agent described in Example 1 can specifically recognize the scaling ion Ca 2+ , and complexed Ca 2+ The capacity can reach 4.8mmol / g and the complexation efficiency can reach 98.7%.

[0100] 2. Particle Fenton activity test

[0101] The multi-stage responsive targeted membrane cleaning agent prepared in Example 1 was tested in a solution containing 10 mg / L humic acid to produce a cascade reaction under the induction of organic matter, and the yield of ·OH was detected.

[0102] The test results show that the PMS / NaClO core-shell particles of the multi-stage responsive targeted membrane cleaning agent described in Example 1 can produce 3.8 mmol / g of ·OH after 2 h of reaction, indicating that the multi-stage responsive targeted membrane cleaning agent can effectively destroy the extracellular polysaccharide matrix in the biofilm and has an excellent biofilm degradation rate.

[0103] 3. Cleaning effect test

[0104] The multi-stage responsive targeted membrane cleaning agent prepared in Example 1 was injected into the submerged membrane module circulation system at 0.1-0.5 wt%. The water environment was in a weakly acidic state, the temperature was maintained at 35-40°C, the circulation flow rate was 1-2 m / s, and the total cleaning time was ≤ 6 hours. The test results are as follows:

[0105] Effect verification: The multi-stage responsive targeted membrane cleaning agent has a cleaning efficiency of 92.1% for CaSO4 scale and mixed biological pollution with a thickness of more than 50μm, which is 35% higher than the traditional EDTA+SDS method, and the membrane contact angle is restored to 98% of the initial value.

[0106] Stability test: After 20 consecutive cleanings using the multi-stage responsive targeted membrane cleaning agent, the membrane flux attenuation rate is ≤8%, and the mechanical tensile strength retention rate is ≥93%.

[0107] These test results demonstrate that the multi-stage responsive targeted membrane cleaning agent combines high cleaning efficiency with low damage, demonstrating remarkable effectiveness in treating complex contamination. After cleaning, membrane performance recovers significantly, extending the membrane's service life. It maintains high efficiency and low damage after repeated use, demonstrating ideal stability and cost-effectiveness. Furthermore, this multi-stage responsive targeted membrane cleaning agent offers mild cleaning operating conditions and a wide range of applications. Compared to traditional methods, it can save time and resources, effectively reducing the operation and maintenance costs of submerged membrane modules.

[0108] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A multi-stage responsive targeted membrane cleaning agent, characterized in that: The multi-stage responsive targeted membrane cleaning agent comprises 5-20% active ingredient, 30-50% carrier material, 0.05-5% membrane passivator, 5-15% anionic surfactant and deionized water; The active ingredients include 1-5% metal ion chelating microspheres, 2-8% oxidized-dispersed core-shell nanoparticles, and 2-7% zwitterionic charge dynamic regulators; The metal ion chelating microspheres are cross-linked microspheres composed of ethylenediaminetetraacetic acid (EDTA) derivatives and sulfonated polystyrene copolymers, encapsulated in the β-cyclodextrin cavity. The oxidative-dispersive core-shell nanoparticles are cored with peroxysulfate (PMS) and a sodium hypochlorite (NaClO) sustained-release agent (SLS) as the shell. The zwitterionic charge dynamic regulator is a pH-responsive amphoteric copolymer. The carrier material is a three-dimensional network thermosensitive hydrogel embedded with active ingredients; The film passivating agent is a functionalized silane coupling agent; The anionic surfactant is at least one of sodium alkyl sulfonate, sodium alkyl aryl sulfonate and sodium alkyl sulfate.

2. A multi-stage responsive targeted membrane cleaning agent according to claim 1, characterized in that: The particle size of the metal ion chelating microspheres is 270-370 nm; the ethylenediaminetetraacetic acid (EDTA) derivative is at least one of EDTA sodium salt, EDTA sodium iron, EDTA esterified derivative, methylglycine diacetic acid (MGDA), and glutamic acid diacetic acid tetrasodium (GLDA).

3. A multi-stage responsive targeted membrane cleaning agent according to claim 1, characterized in that: The particle size of the oxidized-dispersed core-shell nanoparticles is controlled between 10-50 nm.

4. A multi-stage responsive targeted membrane cleaning agent according to claim 1, characterized in that: The zwitterionic charge dynamic regulator is at least one of polyamino acid derivatives, betaines, modified natural zwitterionic polymers, and synthetic zwitterionic polymers.

5. A multi-stage responsive targeted membrane cleaning agent according to claim 1, characterized in that: The three-dimensional network temperature-sensitive hydrogel is N-isopropylacrylamide-based gel or Pluronic F127 hydrogel.

6. A multi-stage responsive targeted membrane cleaning agent according to claim 1, characterized in that: The functionalized silane coupling agent is at least one of aminosilane, epoxysilane, methacryloxysilane, long-chain alkylsilane, fluorosilane, etc.

7. A method for preparing the multi-stage responsive targeted membrane cleaning agent according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Dissolve ethylenediaminetetraacetic acid (EDTA) derivatives and sulfonated polystyrene copolymer in deionized water, add β-cyclodextrin for ultrasonic embedding, and spray dry to obtain metal ion chelating microspheres. The mass ratio of ethylenediaminetetraacetic acid (EDTA) derivatives to sulfonated polystyrene copolymer is 13:7, and the mass ratio of β-cyclodextrin to sulfonated polystyrene copolymer is 5:

4. S2, mixing 2M ammonium sulfate solution and 0.1M ferrous metal solution in a volume ratio of 1:3 to generate a transition metal oxide-supported peroxysulfate magnetic core through a hydrothermal reaction; S3. Coating the surface of the magnetic core obtained in S2 with an inorganic / hypochlorite composite shell layer by a sol-gel method under alkaline conditions, adjusting the molar ratio of the precursor ethyl orthosilicate to sodium hypochlorite to 1:2-1:5, the reaction temperature to 20-50°C, and standing and aging for 12-36 hours to form a core-shell structure with oxidative slow-release function; S4, free radical copolymerizing the carboxylic acid-containing monomer and the sulfobetaine-type monomer in the presence of an initiator, adjusting the pH of the resulting copolymer to neutral and freeze-drying the resulting copolymer to obtain a zwitterionic charge dynamic regulator; S5, dissolving the thermosensitive hydrogel in deionized water to form a sol / micelle system, adding the metal ion chelating microspheres prepared in S1 and the oxidized-dispersed core-shell nanoparticles prepared in S3, adding glycidyl methacrylate (GMA) as a crosslinking agent after ultrasonic dispersion, and standing at low temperature for crosslinking to form a three-dimensional network thermosensitive hydrogel loaded with active ingredients; S6, a silane compound containing epoxy groups and long-chain alkyl groups is mixed, hydrolyzed and activated in an acidic alcohol-water system, and a film passivating agent containing active siloxane groups at the end is formed after the solvent is removed; S7, compounding an anionic surfactant and an auxiliary emulsifier, sodium dioctyl sulfosuccinate AOT, in a mass ratio of 3:2, adding disodium ethylenediaminetetraacetic acid EDTA-Na2 as a complexing stabilizer, and then subjecting the mixture to high shear emulsification and high-pressure homogenization to form a micellar dispersion with a particle size distribution of less than 100 nm, thereby obtaining an anionic surfactant system; S8, crushing the three-dimensional network temperature-sensitive hydrogel obtained in S5 into micron-sized particles, mixing the particles with the anionic surfactant system formed in S7, adding the zwitterionic charge dynamic regulator prepared in S4 and the membrane passivator prepared in S6 stepwise, and stirring thoroughly to form a cleaning agent precursor having a multiphase structure; S9. A freeze-drying-rehydration swelling process is used to quickly freeze the cleaning agent precursor to form directional crystalline ordered channels, and the precursor is vacuum dried and dehydrated at low temperature to retain the nanoscale pore structure. The remaining deionized water in the formula is added and the mixture is swelled at 25°C to a viscosity of 1000-1500 mPa·s to obtain the multi-stage responsive targeted membrane cleaning agent.

8. The method for preparing a multi-stage responsive targeted membrane cleaning agent according to claim 7, characterized in that: The copolymerization reaction system in S4 is protected by inert gas, the temperature is controlled at 60-70° C., and the reaction time is 10 h.

9. Use of the multi-stage responsive targeted membrane cleaning agent according to any one of claims 1 to 8 in cleaning an immersed membrane module.

10. The use of a multi-stage responsive targeted membrane cleaning agent according to claim 9, characterized in that: The cleaning operation is as follows: The multi-stage responsive targeted membrane cleaning agent in emulsion state is injected into the membrane module circulation system at 0.1-0.5wt%. The water environment is in a weakly acidic state, the temperature is maintained at 35-40°C, the circulation flow rate is 1-2m / s, and the total cleaning time is ≤6 hours.

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