A cleaning agent for a filter membrane and a preparation method thereof

Abstract

The present invention provides a cleaning agent for a filter membrane and a preparation method thereof, belonging to the technical field of cleaning agents. It is prepared from the following raw materials in parts by weight: 3-15 parts of a surfactant, 12-40 parts of a solubilizer, 2-5 parts of a pH regulator, and 2-5 parts of a chelating agent. The cleaning agent for the filter membrane prepared by the present invention has a good effect of destroying and removing the scale on the filter membrane, reducing the formation of water scale, destroying the crystal structure of the water scale, thereby promoting the swelling, fluffiness, dispersion and dissolution of the scale, and thus having a good cleaning effect. At the same time, it has good biocompatibility, is safe and environmentally friendly, has no destructive effect on the filter membrane. After use, the scale can be removed by simple rinsing. The use method is simple and efficient, and it has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of cleaning agents, and particularly to a cleaning agent for a filter membrane and a preparation method thereof. Background Art

[0002] Filter membranes tend to foul during processing. In-situ cleaning (CIP) methods can be used to treat the membranes provided in separation equipment to provide rinsing, flushing, pre-treatment, cleaning, disinfection, and preservation. Fouling is manifested as a flux decline over operating time. Flux decline is generally a reduction in the permeate flow or permeation rate that occurs when all operating parameters, such as pressure, feed flow rate, temperature, and feed concentration, are held constant.

[0003] Generally, membrane fouling is a complex process and occurs due to many factors, including electrostatic attraction, hydrophobic and hydrophilic interactions, and the deposition and accumulation of feed components such as suspended particles, non-permeable dissolved solutes, and even normally permeable solutes on the membrane surface and / or within the membrane pores. Almost all feed components are expected to foul the membrane to some extent. Fouling components and deposits can include inorganic salts, particles, microorganisms, and organic matter. Filter membranes generally require regular cleaning to allow for successful industrial applications in separation equipment, such as in process areas like the food, dairy, and beverage industries.

[0004] Chemical energy in the form of detergents and cleaning agents can be used to dissolve or disperse foulants or contaminants. Thermal energy in the form of heat can be used to assist the action of chemical cleaning agents. Generally, the higher the cleaning temperature of a solution, the more effective it is as a cleaning treatment, although most membrane materials have temperature limitations due to the materials they are composed of. Many membranes also have chemical limitations. Generally, it has been found that the type of cleaning agent and the chemical treatment performed on the membrane can affect the working life of the membrane. For example, many polyamide reverse osmosis membranes have a chlorine limitation because chlorine can have an oxidative attack and tend to damage the membrane. Overuse of oxidative chemicals, such as sodium hypochlorite (chlorine bleach) or hydrogen peroxide, will have usage limitations due to irreversibly damaging some polymer membranes.

[0005] Chinese invention patent CN106237864B discloses a reverse osmosis membrane cleaning agent and a using method thereof. The reverse osmosis membrane cleaning agent includes an alkaline cleaning agent and an acidic cleaning agent, and is mainly used to remove single inorganic fouling such as barium strontium scale, and is not suitable for treating complex fouling composed of organic pollutants, inorganic pollutants, and bioactive pollutants such as milk scale. Summary of the Invention

[0006] The object of the present invention is to provide a cleaning agent for a filter membrane and a preparation method thereof, which has a good effect of destroying and removing the scale on the filter membrane, reducing the formation of water scale, destroying the crystal structure of the water scale, thereby promoting the swelling, fluffing, dispersion and dissolution of the scale, and thus having a good cleaning effect. At the same time, it has good biocompatibility, is safe and environmentally friendly, has no destructive effect on the filter membrane, and after use, the scale can be removed by simple rinsing. The use method is simple and efficient, and it has broad application prospects.

[0007] The technical solution of the present invention is realized as follows:

[0008] The present invention provides a cleaning agent for a filter membrane, which is prepared from the following raw materials by weight: 3-15 parts of a surfactant, 12-40 parts of a solubilizer, 2-5 parts of a pH regulator, and 2-5 parts of a chelating agent. The chelating agent is a mixture of a modified chelating agent and a chemical chelating agent, and the mass ratio is 10:3-5. The modified chelating agent is obtained by coating activated carbon with graphene oxide, depositing magnetic iron tetroxide, surface-modifying with tannic acid, loading chitosan and silk fibroin peptide, and reacting the surface with phytic acid and β-cyclodextrin.

[0009] As a further improvement of the present invention, the surfactant is a mixture of decyl glucoside and an anionic surfactant LAS, and the mass ratio is 1:0.5-1. The solubilizer is at least one of propylene glycol, sodium isopropyl sulfonate, and glycerol. The pH regulator is selected from at least one of potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, and sodium hydroxide. The chemical chelating agent is selected from at least one of sodium gluconate, sodium glucoheptonate, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, and tetrasodium glutamate diacetate.

[0010] As a further improvement of the present invention, the preparation method of the modified chelating agent is as follows:

[0011] S1. Pretreatment of activated carbon: Crush and ball-mill woody activated carbon, add it to an alkali solution, perform hydrothermal reaction, centrifuge, wash, and dry to obtain pretreated activated carbon;

[0012] S2. Preparation of pleated activated carbon: Add graphene oxide to water, add pretreated activated carbon, ultrasonically disperse evenly, and spray-dry to obtain pleated activated carbon;

[0013] S3. Preparation of magnetic activated carbon: Add pleated activated carbon to water, under the protection of an inert gas, add ferric chloride and ferrous chloride, dropwise add ammonia water, heat and stir to react, centrifuge, wash, dry, and calcine to obtain magnetic activated carbon;

[0014] S4. Preparation of modified magnetic activated carbon: Add magnetic activated carbon into water, add tannic acid and a catalyst, heat and stir for reaction, separate by a magnet, wash, and dry to obtain modified magnetic activated carbon;

[0015] S5. Preparation of modified magnetic activated carbon composite: Dissolve chitosan in an acid solution, add modified magnetic activated carbon, stir and mix evenly, add NHS and EDC, stir for activation, add silk fibroin peptide, stir for reaction, separate by a magnet, wash, and dry to obtain modified magnetic activated carbon composite;

[0016] S6. Preparation of modified chelating agent: Add modified magnetic activated carbon composite into water, add phytic acid, β-cyclodextrin and dipotassium hydrogen phosphate, heat and stir for reaction, carry out hydrothermal reaction with temperature increase, separate by a magnet, wash, and dry to obtain modified chelating agent.

[0017] As a further improvement of the present invention, in step S1, the alkali solution is a 10-15 wt% NaOH or KOH solution, the temperature of the hydrothermal reaction is 100-120 °C, and the time is 2-4 h; in step S2, the mass ratio of graphene oxide to pretreated activated carbon is 3-5:10, the power of ultrasonic dispersion is 2000-2500 W, and the time is 10-15 min.

[0018] As a further improvement of the present invention, in step S3, the mass ratio of pleated activated carbon, ferric chloride, ferrous chloride and ammonia water is 10:3.24:1.26:4-6, the temperature of the heating and stirring reaction is 80-90 °C, the time is 3-5 h, the temperature of the calcination is 450-550 °C, and the time is 1-2 h.

[0019] As a further improvement of the present invention, in step S4, the mass ratio of magnetic activated carbon, tannic acid and catalyst is 10:4-6:1-2, the catalyst is a Tris-HCl solution with pH = 8.5-9.5, the temperature of the heating and stirring reaction is 45-55 °C, and the time is 3-5 h.

[0020] As a further improvement of the present invention, in step S5, the acid solution is a 1-3 wt% acetic acid or lactic acid solution, the mass ratio of chitosan, modified magnetic activated carbon, NHS, EDC and silk fibroin peptide is 5-7:12-15:1-2:1-2:2-3, the time of the stirring reaction is 10-12 h, and the time of the stirring activation is 20-30 min.

[0021] As a further improvement of the present invention, the mass ratio of the modified magnetic activated carbon composite, phytic acid, β-cyclodextrin and dipotassium hydrogen phosphate in step S6 is 10-15:4-6:3-5:0.5-1. The temperature of the heating and stirring reaction is 70-80 °C, and the time is 2-4 h. The temperature of the temperature-rising hydrothermal reaction is 120-150 °C, and the time is 7-10 h.

[0022] The present invention further protects a preparation method of a cleaning agent for the above-mentioned filter membrane, comprising the following steps: stirring and mixing a surfactant, a solubilizer, a pH regulator and a chelating agent evenly to obtain a cleaning agent for the filter membrane.

[0023] The present invention has the following beneficial effects:

[0024] The present invention uses an alcohol co-solvent and a surfactant co-solvent as co-solvents together, strengthens the synergistic effect between the two, reduces the usage amounts of the two, and improves the solubilization effect; the cleaning agent prepared by the present invention has a low foaming rate, far meets the use standard, and has good stability, and no stratification, crystallization or precipitation occurs when placed in low-temperature and high-temperature environments; in addition, the cleaning agent has good wetting performance with the composite RO membrane, has excellent cleaning effect on it, and can be widely applied to filter membranes. Therefore, the present invention is a composite high-efficiency membrane cleaning agent with excellent stability and excellent cleaning effect on filter membranes.

[0025] The chelating agent of the present invention is a mixture of a modified chelating agent and a chemical chelating agent, wherein the modified chelating agent is obtained by coating activated carbon with graphene oxide, depositing magnetic iron tetroxide, surface-modifying with tannic acid, loading chitosan and silk fibroin peptides, and reacting with phytic acid and β-cyclodextrin on the surface.

[0026] The present invention takes biomass activated carbon as the main body, which has the advantages of wide raw material sources, rich pores, large specific surface area, etc. It is easy to realize the adsorption and separation of fine dust and other substances, so as to remove inorganic small particles on the surface of the filter membrane. After alkali pretreatment, it has a small amount of hydroxyl groups on the surface, which can form hydrogen bonds with the surface of graphene oxide and adsorb graphene oxide on the surface. Graphene oxide is a monolayer structure and contains a large number of oxygen-containing functional groups, including epoxy bridges (-O-), hydroxyl groups (-OH), carboxyl groups (-COOH) and carbonyl groups (=O), which have better chemical stability and reactivity. Through the spray drying process, smaller droplets have a larger specific surface area and can dry faster, forming finer particles. Larger particles may form during the drying process, and these particles may shrink and deform during the drying process, forming a wrinkled structure, further increasing the specific surface area of the product, which is more beneficial to realizing chelation reactions and the adsorption of fine particles. At the same time, the oxygen-containing functional groups on the surface can complex iron ions and ferrous ions, thereby promoting the in-situ formation of magnetic iron tetroxide, which helps to remove and separate the modified chelating agent. At the same time, it also increases the specific surface area of the chelating agent and improves the adsorption capacity for small particles. The surface is modified by tannic acid coating. On the one hand, the organic structure of tannic acid can have an affinity with the filter membrane with a similar structure, causing it to adsorb near the filter membrane and react with the scale on the surface of the filter membrane, promoting the swelling and fluffiness of the scale to form water bubbles. At the same time, other components enter the interior of the scale. The surfactant can coat the scale inside, and the solubilizer promotes the dissolution of organic substances in the scale, thereby destroying, dispersing and dissolving the scale, achieving a good purification effect. On the other hand, the tannic acid coating modification can also couple with chitosan and silk fibroin peptides, so that the surface of the chelating agent is rich in active groups such as amino groups, hydroxyl groups, and carboxyl groups, which can chelate and fix metal ions in water, such as calcium ions and magnesium ions, effectively reducing the formation of scale. It can also carry out charge neutralization and bridging with charged particles in water to form stable flocs. At the same time, it can adsorb organic components in water such as proteins, reducing the formation of scale. The present invention further reacts with phytic acid and β-cyclodextrin on this surface. The rich phosphate groups carried by phytic acid can also improve the scale crystal structure and chelate and stabilize metal ions through chelation, thereby reducing the formation of scale and destroying the scale structure. The organic cavity of β-cyclodextrin can also fix organic components, reducing the deposition of organic scale components such as grease, thus more comprehensively contributing to the destruction and elimination of scale. At the same time, the modified chelating agent prepared by the present invention can also reduce the foaming property of the surfactant to a certain extent and improve the stability of the cleaning agent.

[0027] The cleaning agent for the filter membrane prepared by the present invention has a good effect of destroying and eliminating the scale on the filter membrane, reducing the formation of water scale, destroying the crystal structure of the water scale, thereby promoting the swelling, fluffiness, dispersion and dissolution of the scale, and thus having a good cleaning effect. At the same time, it has good biocompatibility, is safe and environmentally friendly, has no destructive effect on the filter membrane. After use, the scale can be removed by simple rinsing. The use method is simple and efficient, and it has broad application prospects. Detailed implementation mode

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] NHS, N-hydroxysuccinimide; EDC, 1-ethyl-(3-dimethylaminopropyl)carbodiimide.

[0030] Preparation Example 1 Preparation of modified chelating agent

[0031] The method is as follows:

[0032] S1. Pretreatment of activated carbon: Crush 10 g of wood activated carbon, ball mill for 1 h, add it to 200 mL of 10 wt% NaOH solution, heat to 100 °C, carry out hydrothermal reaction for 2 h, centrifuge, wash, and dry to obtain pretreated activated carbon;

[0033] S2. Preparation of pleated activated carbon: Add 3 g of graphene oxide to 200 mL of water, add 10 g of pretreated activated carbon, disperse by ultrasonic wave at 2000 W for 10 min, and spray dry to obtain pleated activated carbon;

[0034] S3. Preparation of magnetic activated carbon: Add 10 g of pleated activated carbon to 200 mL of water. Under nitrogen protection, add 3.24 g of ferric chloride and 1.26 g of ferrous chloride, dropwise add 4 g of ammonia water, heat to 80 °C, stir and react for 3 h, centrifuge, wash, dry, and calcine at 450 °C for 1 h to obtain magnetic activated carbon;

[0035] S4. Preparation of modified magnetic activated carbon: Add 10 g of magnetic activated carbon to 200 mL of water, add 4 g of tannic acid and 1 g of catalyst, heat to 45 °C, stir and react for 3 h, separate by magnet, wash, and dry to obtain modified magnetic activated carbon;

[0036] The catalyst is Tris-HCl solution with pH = 8.5;

[0037] S5. Preparation of modified magnetic activated carbon composite: Dissolve 5 g of chitosan in 200 mL of 1 wt% acetic acid solution, add 12 g of modified magnetic activated carbon, stir and mix for 10 min, add 1 g of NHS and 1 g of EDC, stir and activate for 20 min, add 2 g of silk fibroin peptide, stir and react for 10 h, separate by magnet, wash, and dry to obtain the modified magnetic activated carbon composite;

[0038] S6. Preparation of modified chelating agent: Add 10 g of modified magnetic activated carbon composite to 200 mL of water, add 4 g of phytic acid, 3 g of β-cyclodextrin and 0.5 g of dipotassium hydrogen phosphate, heat to 70 °C, stir and react for 2 h, raise the temperature to 120 °C, carry out hydrothermal reaction for 7 h, separate by magnet, wash, and dry to obtain the modified chelating agent.

[0039] Preparation Example 2 Preparation of modified chelating agent

[0040] The method is as follows:

[0041] S1. Pretreatment of activated carbon: Crush 10 g of wood activated carbon, ball mill for 1 h, add it to 200 mL of 15 wt% KOH solution, heat to 120 °C, carry out hydrothermal reaction for 4 h, centrifuge, wash, and dry to obtain pretreated activated carbon;

[0042] S2. Preparation of pleated activated carbon: Add 5 g of graphene oxide to 200 mL of water, add 10 g of pretreated activated carbon, disperse by ultrasonic wave at 2500 W for 15 min, and spray dry to obtain pleated activated carbon;

[0043] S3. Preparation of magnetic activated carbon: Add 10 g of pleated activated carbon to 200 mL of water, under nitrogen protection, add 3.24 g of ferric chloride and 1.26 g of ferrous chloride, dropwise add 6 g of ammonia water, heat to 90 °C, stir and react for 5 h, centrifuge, wash, dry, and calcine at 550 °C for 2 h to obtain magnetic activated carbon;

[0044] S4. Preparation of modified magnetic activated carbon: Add 10 g of magnetic activated carbon to 200 mL of water, add 6 g of tannic acid and 2 g of catalyst, heat to 55 °C, stir and react for 5 h, separate by magnet, wash, and dry to obtain modified magnetic activated carbon;

[0045] The catalyst is Tris-HCl solution with pH = 9.5;

[0046] S5. Preparation of modified magnetic activated carbon composite: Dissolve 7 g of chitosan in 200 mL of 3 wt% lactic acid solution, add 15 g of modified magnetic activated carbon, stir and mix for 10 min, add 2 g of NHS and 2 g of EDC, stir and activate for 30 min, add 3 g of silk fibroin peptide, stir and react for 12 h, separate by magnet, wash, and dry to obtain the modified magnetic activated carbon composite;

[0047] S6. Preparation of modified chelating agent: Add 15 g of modified magnetic activated carbon composite to 200 mL of water, add 6 g of phytic acid, 5 g of β-cyclodextrin and 1 g of dipotassium hydrogen phosphate, heat to 80 °C, stir and react for 4 h, raise the temperature to 150 °C, carry out hydrothermal reaction for 10 h, separate by magnet, wash, and dry to obtain the modified chelating agent.

[0048] Preparation Example 3 Preparation of modified chelating agent

[0049] The method is as follows:

[0050] S1. Pretreatment of activated carbon: Crush 10 g of wood activated carbon, ball mill for 1 h, add it to 200 mL of 12 wt% NaOH solution, heat to 110 °C, carry out hydrothermal reaction for 3 h, centrifuge, wash, and dry to obtain pretreated activated carbon;

[0051] S2. Preparation of pleated activated carbon: Add 4 g of graphene oxide to 200 mL of water, add 10 g of pretreated activated carbon, ultrasonically disperse at 2250 W for 12 min, and spray dry to obtain pleated activated carbon;

[0052] S3. Preparation of magnetic activated carbon: Add 10 g of pleated activated carbon to 200 mL of water, under nitrogen protection, add 3.24 g of ferric chloride and 1.26 g of ferrous chloride, dropwise add 5 g of ammonia water, heat to 85 °C, stir and react for 4 h, centrifuge, wash, dry, and calcine at 500 °C for 1.5 h to obtain magnetic activated carbon;

[0053] S4. Preparation of modified magnetic activated carbon: Add 10 g of magnetic activated carbon to 200 mL of water, add 5 g of tannic acid and 1.5 g of catalyst, heat to 50 °C, stir and react for 4 h, separate by magnet, wash, and dry to obtain modified magnetic activated carbon;

[0054] The catalyst is Tris-HCl solution with pH = 9;

[0055] S5. Preparation of modified magnetic activated carbon composite: Dissolve 6 g of chitosan in 200 mL of 2 wt% acetic acid solution, add 13 g of modified magnetic activated carbon, stir and mix for 10 min, add 1.5 g of NHS and 1.5 g of EDC, stir and activate for 25 min, add 2.5 g of silk fibroin peptide, stir and react for 11 h, separate by magnet, wash, and dry to obtain modified magnetic activated carbon composite;

[0056] S6. Preparation of modified chelating agent: Add 12 g of modified magnetic activated carbon composite to 200 mL of water, add 5 g of phytic acid, 4 g of β-cyclodextrin and 0.7 g of dipotassium hydrogen phosphate, heat to 75 °C, stir and react for 3 h, raise the temperature to 135 °C, carry out hydrothermal reaction for 8 h, separate with a magnet, wash, and dry to obtain the modified chelating agent.

[0057] Comparative Preparation Example 1

[0058] Compared with Example 3, the difference lies in that step S2 is not carried out.

[0059] Specifically as follows:

[0060] S1. Pretreatment of activated carbon: Crush 10 g of wood-based activated carbon, ball mill for 1 h, add it to 200 mL of 12 wt% NaOH solution, heat to 110 °C, carry out hydrothermal reaction for 3 h, centrifuge, wash, and dry to obtain pretreated activated carbon;

[0061] S2. Preparation of magnetic activated carbon: Add 10 g of pretreated activated carbon to 200 mL of water, under nitrogen protection, add 3.24 g of ferric chloride and 1.26 g of ferrous chloride, dropwise add 5 g of ammonia water, heat to 85 °C, stir and react for 4 h, centrifuge, wash, dry, and calcine at 500 °C for 1.5 h to obtain magnetic activated carbon;

[0062] S3. Preparation of modified magnetic activated carbon: Add 10 g of magnetic activated carbon to 200 mL of water, add 5 g of tannic acid and 1.5 g of catalyst, heat to 50 °C, stir and react for 4 h, separate with a magnet, wash, and dry to obtain modified magnetic activated carbon;

[0063] The catalyst is Tris-HCl solution with pH = 9;

[0064] S4. Preparation of modified magnetic activated carbon composite: Dissolve 6 g of chitosan in 200 mL of 2 wt% acetic acid solution, add 13 g of modified magnetic activated carbon, stir and mix for 10 min, add 1.5 g of NHS and 1.5 g of EDC, stir and activate for 25 min, add 2.5 g of silk fibroin peptide, stir and react for 11 h, separate with a magnet, wash, and dry to obtain modified magnetic activated carbon composite;

[0065] S5. Preparation of modified chelating agent: Add 12 g of modified magnetic activated carbon composite to 200 mL of water, add 5 g of phytic acid, 4 g of β-cyclodextrin and 0.7 g of dipotassium hydrogen phosphate, heat to 75 °C, stir and react for 3 h, raise the temperature to 135 °C, carry out hydrothermal reaction for 8 h, separate with a magnet, wash, and dry to obtain the modified chelating agent.

[0066] Comparative Preparation Example 2

[0067] Compared with Example 3, the difference lies in that step S3 is not carried out.

[0068] Specifically as follows:

[0069] S1. Pretreatment of activated carbon: Crush 10 g of wood-based activated carbon, ball-mill for 1 h, add it to 200 mL of 12 wt% NaOH solution, heat to 110 °C, carry out hydrothermal reaction for 3 h, centrifuge, wash, and dry to obtain pretreated activated carbon;

[0070] S2. Preparation of wrinkled activated carbon: Add 4 g of graphene oxide to 200 mL of water, add 10 g of pretreated activated carbon, disperse by ultrasonic wave at 2250 W for 12 min, and spray-dry to obtain wrinkled activated carbon;

[0071] S3. Preparation of modified magnetic activated carbon: Add 10 g of wrinkled activated carbon to 200 mL of water, add 5 g of tannic acid and 1.5 g of catalyst, heat to 50 °C, stir and react for 4 h, separate by magnet, wash, and dry to obtain modified magnetic activated carbon;

[0072] The catalyst is Tris-HCl solution with pH = 9;

[0073] S4. Preparation of modified magnetic activated carbon composite: Dissolve 6 g of chitosan in 200 mL of 2 wt% acetic acid solution, add 13 g of modified magnetic activated carbon, stir and mix for 10 min, add 1.5 g of NHS and 1.5 g of EDC, stir and activate for 25 min, add 2.5 g of silk fibroin peptide, stir and react for 11 h, separate by magnet, wash, and dry to obtain modified magnetic activated carbon composite;

[0074] S5. Preparation of modified chelating agent: Add 12 g of modified magnetic activated carbon composite to 200 mL of water, add 5 g of phytic acid, 4 g of β-cyclodextrin and 0.7 g of dipotassium hydrogen phosphate, heat to 75 °C, stir and react for 3 h, raise the temperature to 135 °C, carry out hydrothermal reaction for 8 h, separate by magnet, wash, and dry to obtain modified chelating agent.

[0075] Comparative Preparation Example 3

[0076] Compared with Example 3, the difference lies in that step S4 is not carried out.

[0077] Specifically as follows:

[0078] S1. Pretreatment of activated carbon: Crush 10 g of wood-based activated carbon, ball-mill for 1 h, add it to 200 mL of 12 wt% NaOH solution, heat to 110 °C, carry out hydrothermal reaction for 3 h, centrifuge, wash, and dry to obtain pretreated activated carbon;

[0079] S2. Preparation of wrinkled activated carbon: Add 4 g of graphene oxide to 200 mL of water, add 10 g of pretreated activated carbon, disperse by ultrasonic wave at 2250 W for 12 min, and perform spray drying to obtain wrinkled activated carbon;

[0080] S3. Preparation of magnetic activated carbon: Add 10 g of wrinkled activated carbon to 200 mL of water. Under nitrogen protection, add 3.24 g of ferric chloride and 1.26 g of ferrous chloride, dropwise add 5 g of ammonia water, heat to 85 °C, stir and react for 4 h, centrifuge, wash, dry, and calcine at 500 °C for 1.5 h to obtain magnetic activated carbon;

[0081] S4. Preparation of modified magnetic activated carbon composite: Dissolve 6 g of chitosan in 200 mL of 2 wt% acetic acid solution, add 13 g of magnetic activated carbon, stir and mix for 10 min, add 1.5 g of NHS and 1.5 g of EDC, stir and activate for 25 min, add 2.5 g of silk fibroin peptide, stir and react for 11 h, separate by magnet, wash, dry to obtain modified magnetic activated carbon composite;

[0082] S5. Preparation of modified chelating agent: Add 12 g of modified magnetic activated carbon composite to 200 mL of water, add 5 g of phytic acid, 4 g of β-cyclodextrin and 0.7 g of dipotassium hydrogen phosphate, heat to 75 °C, stir and react for 3 h, raise the temperature to 135 °C, perform hydrothermal reaction for 8 h, separate by magnet, wash, dry to obtain modified chelating agent.

[0083] Comparative Preparation Example 4

[0084] Compared with Example 3, the difference is that step S5 is not carried out.

[0085] Specifically as follows:

[0086] S1. Pretreatment of activated carbon: Crush 10 g of wood-based activated carbon, ball mill for 1 h, add it to 200 mL of 12 wt% NaOH solution, heat to 110 °C, perform hydrothermal reaction for 3 h, centrifuge, wash, dry to obtain pretreated activated carbon;

[0087] S2. Preparation of wrinkled activated carbon: Add 4 g of graphene oxide to 200 mL of water, add 10 g of pretreated activated carbon, disperse by ultrasonic wave at 2250 W for 12 min, and perform spray drying to obtain wrinkled activated carbon;

[0088] S3. Preparation of magnetic activated carbon: Add 10 g of wrinkled activated carbon to 200 mL of water. Under nitrogen protection, add 3.24 g of ferric chloride and 1.26 g of ferrous chloride, dropwise add 5 g of ammonia water, heat to 85 °C, stir and react for 4 h, centrifuge, wash, dry, and calcine at 500 °C for 1.5 h to obtain magnetic activated carbon;

[0089] S4. Preparation of modified magnetic activated carbon: Add 10 g of magnetic activated carbon to 200 mL of water, add 5 g of tannic acid and 1.5 g of catalyst, heat to 50 °C, stir and react for 4 h, separate with a magnet, wash, and dry to obtain modified magnetic activated carbon;

[0090] The catalyst is a Tris-HCl solution with a pH of 9;

[0091] S5. Preparation of modified chelating agent: Add 12 g of modified magnetic activated carbon to 200 mL of water, add 5 g of phytic acid, 4 g of β-cyclodextrin, and 0.7 g of dipotassium hydrogen phosphate, heat to 75 °C, stir and react for 3 h, raise the temperature to 135 °C, carry out hydrothermal reaction for 8 h, separate with a magnet, wash, and dry to obtain modified chelating agent.

[0092] Comparative Preparation Example 5

[0093] Compared with Example 3, the difference is that step S6 is not carried out.

[0094] Specifically as follows:

[0095] S1. Pretreatment of activated carbon: Crush 10 g of wood-based activated carbon, ball mill for 1 h, add it to 200 mL of 12 wt% NaOH solution, heat to 110 °C, carry out hydrothermal reaction for 3 h, centrifuge, wash, and dry to obtain pretreated activated carbon;

[0096] S2. Preparation of wrinkled activated carbon: Add 4 g of graphene oxide to 200 mL of water, add 10 g of pretreated activated carbon, disperse by ultrasonic wave at 2250 W for 12 min, and spray dry to obtain wrinkled activated carbon;

[0097] S3. Preparation of magnetic activated carbon: Add 10 g of wrinkled activated carbon to 200 mL of water, under nitrogen protection, add 3.24 g of ferric chloride and 1.26 g of ferrous chloride, dropwise add 5 g of ammonia water, heat to 85 °C, stir and react for 4 h, centrifuge, wash, dry, and calcine at 500 °C for 1.5 h to obtain magnetic activated carbon;

[0098] S4. Preparation of modified magnetic activated carbon: Add 10 g of magnetic activated carbon to 200 mL of water, add 5 g of tannic acid and 1.5 g of catalyst, heat to 50 °C, stir and react for 4 h, separate with a magnet, wash, and dry to obtain modified magnetic activated carbon;

[0099] The catalyst is a Tris-HCl solution with a pH of 9;

[0100] S5. Preparation of modified magnetic activated carbon composite: Dissolve 6 g of chitosan in 200 mL of 2 wt% acetic acid solution, add 13 g of modified magnetic activated carbon composite, stir and mix for 10 min, add 1.5 g of NHS and 1.5 g of EDC, stir and activate for 25 min, add 2.5 g of silk fibroin peptide, stir and react for 11 h, separate by magnet, wash, and dry to obtain the modified magnetic activated carbon composite, which is the modified chelating agent.

[0101] Example 1

[0102] This example provides a cleaning agent for filter membranes, which is prepared from the following raw materials by weight: 3 parts of surfactant, 12 parts of sodium isopropyl sulfonate, 2 parts of sodium bicarbonate, and 2 parts of chelating agent.

[0103] The chelating agent is a mixture of the modified chelating agent prepared in Preparation Example 1 and sodium gluconate, and the mass ratio is 10:3.

[0104] The surfactant is a mixture of decyl glucoside and anionic surfactant LAS, and the mass ratio is 1:0.5.

[0105] The preparation method includes the following steps: Stir and mix the surfactant, sodium isopropyl sulfonate, sodium bicarbonate, and chelating agent evenly to obtain the cleaning agent for filter membranes.

[0106] Example 2

[0107] This example provides a cleaning agent for filter membranes, which is prepared from the following raw materials by weight: 15 parts of surfactant, 40 parts of glycerol, 5 parts of sodium carbonate, and 5 parts of chelating agent.

[0108] The chelating agent is a mixture of the modified chelating agent prepared in Preparation Example 2 and sodium glucoheptonate, and the mass ratio is 10:5.

[0109] The surfactant is a mixture of decyl glucoside and anionic surfactant LAS, and the mass ratio is 1:1.

[0110] The preparation method includes the following steps: Stir and mix the surfactant, glycerol, sodium carbonate, and chelating agent evenly to obtain the cleaning agent for filter membranes.

[0111] Example 3

[0112] This example provides a cleaning agent for filter membranes, which is prepared from the following raw materials by weight: 10 parts of surfactant, 25 parts of propylene glycol, 3 parts of potassium carbonate, and 3 parts of chelating agent.

[0113] The chelating agent is a mixture of the modified chelating agent prepared in Preparation Example 3 and disodium ethylenediaminetetraacetate, and the mass ratio is 10:4.

[0114] The surfactant is a mixture of decyl glucoside and anionic surfactant LAS, and the mass ratio is 1:0.7.

[0115] The preparation method comprises the following steps: stirring and mixing the surfactant, propylene glycol, potassium carbonate and chelating agent evenly to obtain the cleaning agent for the filter membrane.

[0116] Comparative Example 1

[0117] Compared with Example 3, the difference lies in that the modified chelating agent is prepared from Comparative Preparation Example 1.

[0118] Comparative Example 2

[0119] Compared with Example 3, the difference lies in that the modified chelating agent is prepared from Comparative Preparation Example 2.

[0120] Comparative Example 3

[0121] Compared with Example 3, the difference lies in that the modified chelating agent is prepared from Comparative Preparation Example 3.

[0122] Comparative Example 4

[0123] Compared with Example 3, the difference lies in that the modified chelating agent is prepared from Comparative Preparation Example 4.

[0124] Comparative Example 5

[0125] Compared with Example 3, the difference lies in that the modified chelating agent is prepared from Comparative Preparation Example 5.

[0126] Comparative Example 6

[0127] Compared with Example 3, the difference lies in that the chelating agent is disodium ethylenediaminetetraacetate.

[0128] Comparative Example 7

[0129] Compared with Example 3, the difference lies in that no solubilizer is added.

[0130] Test Example 1

[0131] The cleaning agents for the filter membranes prepared in Examples 1-3 and Comparative Examples 6 and 7 of the present invention were subjected to performance tests, and the results are shown in Table 1.

[0132] (1) Foaming performance test

[0133] Take the cleaning agent for the filter membrane, dilute it with water to 100 mg / mL, stir evenly, the experimental temperature is 45 ± 2 °C, take 20 mL of the aqueous solution and pour it into a 100 mL stoppered graduated cylinder, then add 10 mL of warm water, shake it violently up and down 25 times, record the foam height at this time, and after standing for 5 min, record the foam height again. Repeat the test 3 times and take the average value.

[0134] (2)Stability performance test

[0135] Place the cleaning agent at low temperature (-5±2°C) for 24 hours and in a high-temperature environment (60±2°C) for 6 hours respectively, and then let it stand at room temperature to check whether it is uniform, and whether there are phenomena of stratification, crystallization or precipitation.

[0136] (3)Contact angle performance test

[0137] The smaller the contact angle, the better the wetting performance of the liquid on the solid surface. Use a contact angle measuring instrument to measure the contact angle between the polyamide composite RO membrane and the cleaning agent of the filter membrane.

[0138] Table 1

[0139]

[0140] As can be seen from the above table, the cleaning agent of the filter membrane prepared in Examples 1-3 of the present invention has a low foaming height, good stability, a small contact angle and good wettability. In Comparative Example 6, the modified chelating agent was not added, and its foaming performance decreased. It can be seen that the modified chelating agent can reduce the foaming height to a certain extent and destroy the formation of foam. In Comparative Example 7, the solubilizer was not added, and both the contact angle and the foam height increased significantly. It can be seen that the solubilizer can improve the wettability of the cleaning agent and at the same time destroy the formation of foam.

[0141] Test Example 2

[0142] Adopt the Millipore Labscale TMTFF System ultrafiltration equipment. The cut-off molecular weight of the ultrafiltration membrane is 10KDa, the membrane material is PES, and the effective filtration area of the membrane module is 50 cm 2 , the ultrafiltration conditions are 0.2 MPa and 70°C; ultrafilter the whole milk under the above conditions, and measure the membrane flux after pollution at 180 minutes. The whole milk is of the same brand commercially available; use the cleaning agent of the filter membrane prepared in Examples 1-3 or Comparative Examples 1-7 of the present invention to prepare an aqueous solution with a concentration of 0.5% for cleaning. The overall cleaning time is controlled within 2 hours. After cleaning, conduct a cleaning effect test, and use the flux recovery rate WFR (water flux recovery) to represent it. The larger the WFR, the better the cleaning effect of the cleaning agent. The flux recovery rate (%) is calculated according to the following formula:

[0143]

[0144] In the formula, Jwc is the pure water flux of the membrane after cleaning, L / m 2 ·h; Jwf is the pure water flux of the membrane after pollution, L / m 2 ·h; Jwi is the pure water flux of the membrane before pollution, L / m 2 ·h.

[0145] The results are shown in Table 2.

[0146] Table 2

[0147]

[0148] As can be seen from the above table, the cleaning agent for the filtration membrane prepared in Examples 1-3 of the present invention has a good cleaning effect on the ultrafiltration membrane.

[0149] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A cleaning agent for a filter membrane, characterized in that: The invention is prepared from the following raw materials in parts by weight: 3-15 parts of a surfactant, 12-40 parts of a solubilizer, 2-5 parts of a pH regulator and 2-5 parts of a chelating agent. The chelating agent is a mixture of a modified chelating agent and a chemical chelating agent in a mass ratio of 10:3-5. The modified chelating agent is a modified chelating agent prepared by coating activated carbon with graphene oxide, depositing magnetic ferroferric oxide, modifying the surface with tannic acid, loading chitosan and silk protein peptide, and reacting the surface with phytic acid and beta-cyclodextrin.

2. The cleaning agent for the filter membrane according to claim 1, characterized in that: The surfactant is a mixture of decyl glucoside and anionic surfactant LAS, with a mass ratio of 1:0.5-1; the solubilizer is at least one of propylene glycol, sodium isopropyl sulfonate, and glycerol; the pH adjuster is at least one of potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, and sodium hydroxide; and the chemical chelating agent is at least one of sodium gluconate, sodium gluconate heptanoate, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, and tetrasodium glutamate diacetate.

3. The cleaning agent for the filter membrane according to claim 2, characterized in that: The preparation method of the modified chelating agent is as follows: S1. Pretreatment of activated carbon: crushing wood activated carbon, ball milling, adding to alkali solution, hydrothermal reaction, centrifugation, washing, drying, and obtaining pretreated activated carbon; S2. Preparation of wrinkled activated carbon: adding graphene oxide to water, adding pretreated activated carbon, ultrasonically dispersing uniformly, spray drying, and obtaining wrinkled activated carbon; S3. Preparation of magnetic activated carbon: adding creased activated carbon to water, adding ferric chloride and ferrous chloride under inert gas protection, adding ammonia water dropwise, heating and stirring the reaction, centrifuging, washing, drying, and calcining to obtain magnetic activated carbon; S4. Preparation of modified magnetic activated carbon: adding magnetic activated carbon to water, adding tannic acid and a catalyst, heating and stirring to react, separating with a magnet, washing, and drying to obtain modified magnetic activated carbon; S5. Preparation of modified magnetic activated carbon composite: dissolving chitosan in acid solution, adding modified magnetic activated carbon, stirring and mixing evenly, adding N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide, stirring and activating, adding silk fibroin peptide, stirring and reacting, separating with a magnet, washing, and drying to obtain a modified magnetic activated carbon composite; S6. Preparation of modified chelating agent: Add the modified magnetic activated carbon composite into water, add phytic acid, β-cyclodextrin and dipotassium hydrogen phosphate, heat and stir to react, increase the temperature for hydrothermal reaction, separate with a magnet, wash and dry to obtain the modified chelating agent.

4. The cleaning agent for the filter membrane according to claim 3, characterized in that: The alkali solution in step S1 is a 10-15wt% NaOH or KOH solution, the temperature of the hydrothermal reaction is 100-120°C, and the time is 2-4h; the mass ratio of graphene oxide and pretreated activated carbon in step S2 is 3-5:10, the power of the ultrasonic dispersion is 2000-2500W, and the time is 10-15min.

5. The cleaning agent for the filter membrane according to claim 3, characterized in that: The mass ratio of the creased activated carbon, ferric chloride, ferrous chloride and ammonia water in step S3 is 10: 3.24:1.26:4-6, the temperature of the heating and stirring reaction is 80-90°C, the time is 3-5h, the temperature of the calcination is 450-550°C, the time is 1-2h.

6. The cleaning agent for the filter membrane according to claim 3, characterized in that: The mass ratio of the magnetic activated carbon, tannic acid and catalyst in step S4 is 10:4-6:1-2, the catalyst is a Tris-HCl solution with a pH of 8.5-9.5, the temperature of the heating and stirring reaction is 45-55° C., and the time is 3-5 hours.

7. The cleaning agent for the filter membrane according to claim 3, characterized in that: The acid solution in step S5 is 1-3wt% acetic acid or lactic acid solution, the mass ratio of chitosan, modified magnetic activated carbon, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and silk fibroin peptide is 5-7:12-15:1-2:1-2:2-3, the stirring reaction time is 10-12h, and the stirring activation time is 20-30min.

8. The cleaning agent for the filter membrane according to claim 3, characterized in that: The mass ratio of the modified magnetic activated carbon composite, phytic acid, β-cyclodextrin and dipotassium hydrogen phosphate in step S6 is 10-15:4-6:3-5:0.5-1, the temperature of the heating and stirring reaction is 70-80°C, the time is 2-4h, and the temperature of the hydrothermal reaction is increased to 120-150°C, and the time is 7-10h.

9. A method for preparing a cleaning agent for a filter membrane according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: stirring and mixing a surfactant, a solubilizing agent, a pH adjusting agent and a chelating agent uniformly to prepare a cleaning agent for a filter membrane.

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