Composition for cleaning separator and manufacturing method thereof

Abstract

The present invention relates to a composition for cleaning a separator and a manufacturing method thereof, the composition for cleaning a separator, according to the present invention, comprising keto beads, and being able to control contamination of a separator whilst exhibiting good cleaning efficiency.

Description

Composition for cleaning membrane and method for manufacturing same

[0001] The present invention relates to a composition for cleaning a separation membrane and a method for producing the same.

[0002] Microbeads, mostly synthetic polymer particles, have been widely used as scrubbers to enhance the cleaning efficiency of cleansers. Despite their effectiveness, microbeads pose a problem because, after use, they are flushed down sewers and reach the ecosystem, where they are ingested by various aquatic organisms. Therefore, research has been conducted to develop alternatives to these harmful microbeads, and recently, "chitobeads," reacetylated chitosan, have been proposed as an alternative. Chitosan is a biopolymer derived from chitin, a natural polysaccharide found in the exoskeletons of crustaceans and certain fungi. Chitosan has the ability to adsorb heavy metals, ions, dyes, oils, and other contaminants through coordination sites provided by amino and hydroxyl groups. Its positive surface charge provides a high affinity for negatively charged particles and microbial organisms, and it can also provide antimicrobial and adhesive properties. Due to these properties, chitosan is used in water treatment processes not only for metal adsorption but also as an antimicrobial and antibacterial agent.

[0003] Due to global climate change-induced water resource inequality, technologies such as desalination and wastewater treatment are attracting attention for sustainable water resource supply regardless of climate change. One method for producing clean water through desalination and wastewater regeneration is membrane-based water treatment processes. Reverse osmosis, in particular, is widely used due to its ability to reject not only bacteria, organic matter, and divalent ions, but also monovalent ions present in the feedwater. However, fouling, the adhesion of substances rejected by the membrane, reduces water flow and increases operating costs. Various strategies are being studied to control this, including membrane modification using antifouling agents, blocking bacterial signaling, and optimizing operating conditions. However, flux reduction is inevitable, necessitating physicochemical cleaning of the membrane surface. Dedicated physical cleaning strategies such as aeration, backwashing, and air or CO2 bubbling have been limited in effectiveness, and chemical cleaning using acids, alkalis, chelating agents, surfactants, and chlorine species has been utilized. Among these, ionic liquids effectively control organic-contaminated membranes through a unique mechanism that involves the expansion of the contaminant layer. However, irreversible fouling, which is the incomplete recovery of water flow due to physicochemical cleaning, is unavoidable. Therefore, the development of strategies to control irreversible fouling is becoming increasingly important in membrane-based water treatment processes.

[0004] The background technology described above is something that the inventor possessed or acquired in the process of deriving the disclosure of the present application, and cannot necessarily be said to be a publicly known technology disclosed to the general public prior to the present application.

[0005] The present invention aims to solve the above-described problem by providing a composition for cleaning a membrane including a kite bead and a method for manufacturing the same.

[0006] The present invention aims to effectively control irreversible contamination of a separation membrane due to fouling by providing a separation membrane cleaning composition containing chito beads.

[0007] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by a person having ordinary skill in the relevant technical field from the description below.

[0008] The membrane cleaning composition according to the present invention comprises chito beads.

[0009] In one embodiment, the kite beads may have a diameter of 1 μm to 500 μm.

[0010] In one embodiment, the chitosan beads may be present in an amount of from 0.01 wt% to 10 wt% of the composition.

[0011] In one embodiment, the kite beads may have an ion adsorption capacity of 1 mg / g to 10 mg / g.

[0012] In one embodiment, it may further comprise an ionic liquid.

[0013] In one embodiment, the ionic liquid is selected from the group consisting of 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium tetraborate, 1-vinyl-3ethylimidazoliumbis(trifluoromethylsulfonyl)amide, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-octyl-3-methylimidazolium chloride, and 1-octyl-3-methylimidazolium It may comprise at least one selected from the group consisting of bromide (1-octyl-3-methylimidazolium bromide).

[0014] In one embodiment, the ionic liquid may be present in an amount of 0.01 wt% to 5 wt% of the composition.

[0015] According to one embodiment, the separation membrane may be a reverse osmosis membrane used in a water treatment process.

[0016] In one embodiment, the composition may have a pH of 4 to 14.

[0017] In one embodiment, the composition may be capable of cleaning irreversible contaminants attached to the membrane.

[0018] In one embodiment, the contaminant may include at least one selected from the group consisting of humic acid, alginic acid, peptides, heavy metals, metal ions, microorganisms, microbial biofilms, and extracellular polymeric substances (EPS).

[0019] In one embodiment, the flux recovery rate after the cleaning may be 75% or more.

[0020] According to one embodiment, the surface roughness of the separation membrane after the cleaning may have an increase rate of 30% or less compared to the surface roughness of the separation membrane before the contamination source is attached.

[0021] A method for manufacturing a membrane cleaning composition according to the present invention comprises the steps of: preparing a mixed solution by dispersing a chitosan solution in an oil solution; crosslinking by adding a crosslinking agent to the mixed solution; washing after centrifugation; and drying to obtain chito beads.

[0022] According to one embodiment, the chitosan solution may have a chitosan content of 2 wt% to 10 wt%, and a weight ratio of the chitosan solution and the oil solution may be 1:2 to 1:7.

[0023] According to one embodiment, after the step of obtaining the chito beads, the method may further include a step of mixing the chito beads and the ionic liquid.

[0024] The present invention can provide a composition for cleaning a membrane including a kite bead and a method for manufacturing the same.

[0025] Specifically, the membrane cleaning composition according to the present invention can provide an improved fouling control strategy that can alleviate irreversible fouling of the membrane and improve the long-term performance and operating life of the membrane in an environmentally friendly manner due to its physical cleaning properties that interact with the contaminants of the chitosan beads and promote their separation from the membrane surface and its chemical properties that effectively remove heavy metal contaminants by forming complexes with metal ions through chelation.

[0026] Figure 1 is a schematic diagram showing a method for manufacturing a membrane cleaning composition according to the present invention.

[0027] Figures 2a to 2d show SEM images and size distributions of chito beads according to an embodiment of the present invention.

[0028] Figure 3 shows the FT-IR spectra of chitosan and chito beads according to an embodiment of the present invention.

[0029] Figure 4 is a graph showing the Cu ion adsorption capacity of a kite bead according to an embodiment of the present invention.

[0030] Figures 5a to 5d show the maximum interaction energy distribution per unit area of ​​chitosan and humic acid according to an embodiment of the present invention.

[0031] Figures 6a and 6b show the flux recovery rate of a humic acid contaminated film according to an embodiment of the present invention.

[0032] Figure 7 is a photographic image of a membrane according to an embodiment of the present invention.

[0033] Figure 8 is an SEM image showing the surface morphology of a membrane according to an embodiment of the present invention.

[0034] Figure 9 shows the roughness of a membrane according to an embodiment of the present invention.

[0035] Figure 10 shows the results of SEM-EDS analysis of a membrane according to an embodiment of the present invention.

[0036] Hereinafter, embodiments are described in detail with reference to the attached drawings. However, the embodiments may be modified in various ways, and the scope of the patent application is not limited or restricted by these embodiments. It should be understood that all modifications, equivalents, or alternatives to the embodiments are included within the scope of the patent application.

[0037] The terms used in the examples are for illustrative purposes only and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but should be understood to not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0038] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the embodiments pertain. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0039] In addition, when describing with reference to the attached drawings, the same components will be given the same reference numerals regardless of the drawing numbers, and redundant descriptions thereof will be omitted. When describing an embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted. In addition, when describing a component of an embodiment, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only to distinguish the component from other components, and the nature, order, or sequence of the component is not limited by the terms. When a component is described as being "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but another component may also be "connected," "coupled," or "connected" between each component.

[0040] Components included in one embodiment and components with common functions will be described using the same names in other embodiments. Unless otherwise stated, the descriptions given in one embodiment can be applied to other embodiments, and detailed descriptions will be omitted to the extent of overlap.

[0041]

[0042] The membrane cleaning composition according to the present invention comprises chito beads.

[0043] The above membrane cleaning composition is for cleaning a membrane having selective permeability and can be used in a water treatment process. The water treatment process is one of the methods for producing clean water through desalination and wastewater regeneration. The membrane acts as a filter that allows water to pass through but prevents suspended solids from passing through, thereby producing clean water. However, there is a problem with membrane fouling, in which contaminants adhere to the membrane surface, lowering its performance. Since a decrease in flux is inevitable due to this, physicochemical cleaning to remove contaminants such as heavy metals and ions from the membrane surface is important to solve this problem. This can be said to be a key factor in determining the performance and lifespan of the membrane.

[0044] The membrane cleaning composition according to the present invention, compared to conventional membrane cleaning methods using only chemical cleaning agents, enhances cleaning efficiency through the inclusion of chitosan beads and mechanical impact. It possesses superior physicochemical cleaning efficacy, preventing membrane degradation without damaging the membrane during membrane cleaning. Furthermore, it increases reusability, extending the lifespan of water treatment membranes and reducing water treatment costs.

[0045] Specifically, the chitosan beads are microbeads manufactured from chitosan, which is a biopolymer extracted from chitin, a natural polysaccharide found in the exoskeletons of crustaceans and certain fungi. Chitosan has excellent antibacterial, adsorption, heavy metal removal, and adhesive properties, and thus has the potential to replace microplastic-based detergents. In particular, it can adsorb organic species and metal ions with various interactions, and has therefore been widely utilized in adsorption applications. However, there has been no study on the application of spherical chitosan beads obtained by reacetylating chitosan to control membrane fouling using organic contaminants. When chitosan beads are used as a cleaning solution, they may cause particulate fouling rather than functioning as a cleaning agent. However, the chitosan beads according to the present invention enhance cleaning efficiency through chemical adsorption of organic substances and metal ions and mechanical separation of contaminants from the membrane surface, instead of precipitating on the membrane surface and causing particulate fouling. Adding chitobeads to the cleaning solution effectively interacts with heavy metals and other pollutants through chelation, complex formation with metal ions, and interaction with pollutants. The aeration process enhances the mechanical collision between chitobeads and pollutants on the membrane surface, resulting in excellent cleaning effects. It is also environmentally friendly due to its non-toxicity.

[0046]

[0047] In one embodiment, the kite beads may have a diameter of 1 μm to 500 μm.

[0048] The diameter is preferably 1 μm to 400 μm; 1 μm to 300 μm; 1 μm to 200 μm; 1 μm to 100 μm; 1 μm to 50 μm; 10 μm to 500 μm; 10 μm to 400 μm; 10 μm to 300 μm; 10 μm to 200 μm; 10 μm to 100 μm; 10 μm to 50 μm; 50 μm to 500 μm; 50 μm to 400 μm; 50 μm to 300 μm; 50 μm to 200 μm; 50 μm to 100 μm; 100 μm to 500 μm; 100 μm to 400 μm; It may be 100 ㎛ to 300 ㎛; 100 ㎛ to 200 ㎛; 200 ㎛ to 500 ㎛; 200 ㎛ to 400 ㎛; 200 ㎛ to 300 ㎛; 300 ㎛ to 500 ㎛; 300 ㎛ to 400 ㎛; or 400 ㎛ to 500 ㎛.

[0049] If the diameter is less than the above range, the cleaning efficiency may decrease, and there may be a problem of impurities acting in the membrane cleaning process. If the diameter exceeds the above range, the cleaning efficiency may decrease rapidly. When the diameter of the chitosan beads is included within the above range, the cleaning efficiency may be improved.

[0050]

[0051] In one embodiment, the chitosan beads may be present in an amount of from 0.01 wt% to 10 wt% of the composition.

[0052] The chitobeads are preferably present in an amount of from 0.01 wt% to 5 wt% of the composition; from 0.01 wt% to 1 wt%; from 0.01 wt% to 0.5 wt%; from 0.01 wt% to 0.1 wt%; from 0.01 wt% to 0.05 wt%; from 0.05 wt% to 10 wt%; from 0.05 wt% to 5 wt%; from 0.05 wt% to 1 wt%; from 0.05 wt% to 0.5 wt%; from 0.05 wt% to 0.1 wt%; from 0.1 wt% to 10 wt%; from 0.1 wt% to 5 wt%; from 0.1 wt% to 1 wt%; from 0.1 wt% to 0.5 wt%; from 0.5 wt% to 10 wt%; from 0.5 wt% to 5 wt%; from 0.5 wt% to 1 wt%; It may be 1 wt% to 10 wt%; 1 wt% to 5 wt%; or 5 wt% to 10 wt%.

[0053] If it is below the above range, there may be a problem of not being able to clean, and if it is above the above range, there may be a problem of the beads self-aggregating, reducing the cleaning efficiency.

[0054]

[0055] In one embodiment, the kite beads may have an ion adsorption capacity of 1 mg / g to 10 mg / g.

[0056] The above ions may include at least one selected from the group consisting of lead, copper, and mercury. Chitosan can adsorb potentially toxic elements due to the presence of amino (-NH2) and hydroxyl (-OH) groups, which serve as coordination and reaction sites. The amount of ion adsorption may be determined by adding chitosan beads to an ion solution, stirring, and measuring the ion concentration using ICP-OES.

[0057] The above ion adsorption amount may preferably be 1 mg / g to 8 mg / g; 3 mg / g to 8 mg / g; or 3 mg / g to 5 mg / g.

[0058] Ion adsorption capacity is closely related to the surface area-to-mass ratio, and toxic elements can be adsorbed while exhibiting an ion adsorption capacity within the above range. If it falls below the above range, there may be a problem of insufficient element adsorption, resulting in insufficient cleaning efficiency. If it exceeds the above range, there may be a problem of difficulty in removing the beads during the process.

[0059]

[0060] In one embodiment, it may further comprise an ionic liquid.

[0061] Ionic liquids are organic salts formed by ionic bonds between cations and anions, and can be defined as existing in a liquid state at relatively low temperatures below 100°C. These ionic liquids have a cleaning effect and can clean membranes contaminated with organic substances through a unique cleaning mechanism that involves the expansion of the contaminant layer.

[0062] The membrane cleaning composition according to the present invention can exhibit excellent cleaning efficiency by including the ionic liquid and chito beads together, thereby causing the chito beads to swell and effectively disrupt the hydrolyzed contaminant layer through mechanical collision with the ionic liquid.

[0063]

[0064] In one embodiment, the ionic liquid is selected from the group consisting of 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium tetraborate, 1-vinyl-3ethylimidazoliumbis(trifluoromethylsulfonyl)amide, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-octyl-3-methylimidazolium chloride, and 1-octyl-3-methylimidazolium It may comprise at least one selected from the group consisting of bromide (1-octyl-3-methylimidazolium bromide).

[0065] An ionic liquid having a π group may be effective in controlling organic contamination, preferably 1-ethyl-3-methylimidazolium acetate.

[0066]

[0067] In one embodiment, the ionic liquid may be present in an amount of 0.01 wt% to 5 wt% of the composition.

[0068] The ionic liquid may preferably be present in an amount of 0.01 wt% to 1 wt%; 0.01 wt% to 0.5 wt%; 0.01 wt% to 0.1 wt%; 0.1 wt% to 5 wt%; 0.1 wt% to 1 wt%; 0.1 wt% to 0.5 wt%; 0.5 wt% to 5 wt%; 0.5 wt% to 1 wt%; or 1 wt% to 5 wt% of the composition.

[0069] If it is below the above range, there may be a problem of reduced cleaning efficiency, and if it is above the above range, the phenomenon of beads dissolving in the ionic liquid may occur.

[0070]

[0071] According to one embodiment, the separation membrane may be a reverse osmosis membrane used in a water treatment process.

[0072] In water treatment processes, separation membranes can be classified according to their separation performance. Among them, an osmotic membrane is a membrane for separating solutions with different concentrations. It is a membrane used for the osmotic phenomenon in which water from a low-concentration solution passes through the membrane and moves toward a high-concentration solution after a certain period of time. Reverse osmosis is a phenomenon in which water is sent to a low-concentration solution by applying a pressure higher than the osmotic pressure to a high-concentration solution. The separation membrane used in this process is a reverse osmosis membrane.

[0073] The above reverse osmosis membrane is made of ethyl cellulose, hydroxypropyl methylcellulose, cellulose acetate, cellulose triacetate, cellulose acetate-cellulose triacetate blend, polyvinylpyrrolidone, polyvinylpyrrolidone-vinylacetate copolymer, polymethyl methacrylate, polyamine, polyimide, polyether imide, polyamide, polybenzimidazole, polybenzimidazolone, polyethylene-vinyl acetate, polyvinyl alcohol, polyethylene, polypropylene, polyethylene oxide, polyacrylonitrile, polyacrylonitrile-polyvinyl chloride copolymer, polysulfone, polyethersulfone, polydimethylphenylene oxide, polyvinylidene fluoride, polytetrafluoroethylene, polycarbonate, polyvinyl chloride, gelatin, glucose, saccharides, povidone, caphovidone. and may include at least one selected from the group consisting of silicon.

[0074]

[0075] In one embodiment, the composition may have a pH of 4 to 14.

[0076] Preferably, the pH may be 6 to 14; 6 to 12; 8 to 12; or 8 to 10.

[0077] It is known that the adsorption capacity of chitosan decreases dramatically as the pH of the solution increases compared to acidic and neutral pH conditions, but the present invention can provide a cleaning solution composition having excellent cleaning capacity even under alkaline conditions by effectively disturbing the contaminated layer through mechanical collision using chito beads.

[0078]

[0079] In one embodiment, the composition may further comprise a pH adjusting agent.

[0080] The above pH adjusting agent may include at least one selected from the group consisting of sodium hydroxide, calcium hydroxide, magnesium hydroxide, sodium silicate, sodium aluminate, potassium hydroxide, sodium carbonate, sodium bicarbonate, and potassium carbonate.

[0081] Preferably, it may be sodium hydroxide. While the ionic liquid induces swelling of the contaminated layer, the sodium hydroxide hydrolyzes the organic matter in the contaminated layer, so the cleaning efficiency can be increased by the synergistic cleaning effect of the ionic liquid and sodium hydroxide.

[0082]

[0083]

[0084] In one embodiment, the composition may be capable of cleaning irreversible contaminants attached to the membrane.

[0085] In water treatment processes, fouling, a phenomenon in which substances rejected by membranes adhere, reduces water flow and increases operating costs. Therefore, cleaning is necessary. Contaminants resulting from fouling can include organic, inorganic, and microbial contaminants. While inorganic contaminants can be removed using chemical cleaning methods, irreversible contaminants such as organic and microbial contaminants adhere to the membrane and are therefore difficult to remove with chemical cleaning.

[0086] The composition according to the present invention can exhibit excellent cleaning efficacy against irreversible contaminants by including chitosan beads. The physical cleaning properties of chitosan beads arise from their ability to interact with contaminants and promote their separation from the membrane surface, and can effectively remove contaminants through various interactions between the contaminant and chitosan, such as electrostatic interactions, hydrophobic interactions, cation-π interactions, and hydrogen bonding.

[0087] During the above cleaning, the cross-flow velocity of the membrane cleaning composition may be 15 cm / s to 25 cm / s.

[0088]

[0089] In one embodiment, the contaminant may include at least one selected from the group consisting of humic acid, alginic acid, peptides, heavy metals, metal ions, microorganisms, microbial biofilms, and extracellular polymeric substances (EPS).

[0090] Preferably, it may be humic acid. Humic acid is abundant among natural organic substances in the feedwater of membrane-based water treatment processes, and can act as a representative pollutant due to its characteristic of acting as cement during the formation of a contaminant layer.

[0091]

[0092] In one embodiment, the flux recovery rate after the cleaning may be 75% or more.

[0093] Flux recovery, which represents the membrane's water permeability, is calculated as the percentage of the membrane's post-cleaning flux divided by the initial flux. Flux may decrease if the membrane becomes fouled.

[0094] Preferably, the flux recovery rate may be 80% or more.

[0095] While exhibiting the above flux recovery rate, excellent cleaning effects can be achieved. This can be explained by the separation of the fouling layer from the membrane surface through various chemical interactions and mechanical collisions between the chitosan beads and the fouling source. If the flux recovery rate falls below the above range, the cleaning effect may be reduced.

[0096]

[0097] According to one embodiment, the surface roughness of the separation membrane after the cleaning may have an increase rate of 30% or less compared to the surface roughness of the separation membrane before the contamination source is attached.

[0098] The surface roughness of a membrane can increase due to a fouling layer created by organic substances. The surface roughness of the membrane after cleaning using a cleaning solution containing the chitosan beads of the present invention can approach the surface roughness of the membrane before contamination, thereby demonstrating excellent cleaning efficiency.

[0099]

[0100] In one embodiment, no metal ions may be detected in the separation membrane after the cleaning.

[0101] Metal ions can be detected in membranes with attached contaminants, especially humic acid contaminated membranes. The metal ions may include sodium, calcium, or both. Specifically, calcium ions include Ca 2+ It is known to form complexes with humic acid through cross-linking, further developing a dense fouling layer on the membrane surface. Ions present in the fouling layer can form complexes with the amine groups of chitosan and be adsorbed onto the chitobeads, thereby preventing the membrane from containing metal ions after cleaning.

[0102]

[0103] A method for manufacturing a membrane cleaning composition according to the present invention comprises the steps of: preparing a mixed solution by dispersing a chitosan solution in an oil solution; crosslinking by adding a crosslinking agent to the mixed solution; washing after centrifugation; and drying to obtain chito beads.

[0104] Figure 1 is a schematic diagram showing a method for preparing a membrane cleaning composition according to the present invention. Chito beads can be prepared using an emulsification method. Referring to Figure 1, a liquid phase chitosan solution (101) can be dispersed in an oil phase oil solution (102). Thereafter, a stirring process may be performed to form an emulsion through appropriate dispersion. Thereafter, a cross-linking step may be performed by adding a cross-linking agent (103). Thereafter, chito beads (104) can be obtained through centrifugation, washing, and drying. The obtaining step may be to obtain chito beads of various sizes by sieving after drying. The method for preparing a membrane cleaning composition according to the present invention can obtain uniform and excellent chito beads, thereby forming a membrane cleaning composition.

[0105] The step of preparing the above mixed solution may include a stirring step. The stirring step may be performed at a speed of 700 rpm to 900 rpm for 1 to 10 minutes after dispersing the chitosan solution in the oil solution.

[0106] The crosslinking agent may include at least one selected from the group consisting of epichlorohydrin, ethylene glycol diglycidyl ether, glutaraldehyde, benzoquinone, phosphorus oxychloride, malic anhydride, and isocyanate. The crosslinking step may be performed for 30 minutes to 3 hours, and preferably, may be performed twice.

[0107]

[0108] According to one embodiment, the chitosan solution may have a chitosan content of 2 wt% to 10 wt%, and a weight ratio of the chitosan solution and the oil solution may be 1:2 to 1:7.

[0109] Preferably, the chitosan content of the chitosan solution may be 2 wt% to 5 wt%.

[0110] When the weight ratio of the chitosan solution and the oil solution is within the above range, chitosan beads of uniform size and shape can be manufactured.

[0111] The above oil solution may include at least one selected from the group consisting of triethylhexanoin, diisosteryl malmitate, triglyceride, trimethicone, dimethicone, phenyl trimethicone, cyclohexasiloxane, and cyclopentasiloxane, liquid paraffin, squalane, mineral oil, triglycerin, canola oil, olive oil, macadamia nut oil, sunflower oil, palm oil, and horse oil.

[0112]

[0113] According to one embodiment, after the step of obtaining the chito beads, the method may further include a step of mixing the chito beads and the ionic liquid.

[0114] A membrane cleaning composition can be prepared by mixing chito beads and an ionic liquid. The weight ratio of the chito beads and the ionic liquid may be 1:5 to 10:1. Preferably, it may be 1:5 to 8:1; 1:3 to 8:1; 1:3 to 5:1; 1:1 to 5:1; 1:1 to 3:1; or 3:1 to 1:1. When mixed within the above range, a cleaning composition exhibiting excellent cleaning efficiency can be provided.

[0115]

[0116] Hereinafter, the present invention will be described in more detail by way of examples and comparative examples.

[0117] However, the following examples are only intended to illustrate the present invention, and the content of the present invention is not limited to the following examples.

[0118]

[0119] Example

[0120] Manufacturing of chito beads

[0121] Chito beads were prepared using a liquid-on-oil (w / o) emulsion method. The liquid phase consisted of a 4 wt% chitosan and 2% (w / v) NaCl chitosan solution in a 5% (v / v) acetic acid solution, and the oil phase was a mixture of canola oil (35 mL) and hexane (25 mL) with 0.85 g of sorbitan sesquioleate. The manufacturing process was carried out in a 100 mL round-bottomed flask.

[0122] To initiate the formation of chitosan beads, 0.6 g of chitosan solution was dispersed in the oil phase using a syringe. The mixture was then stirred at 850 rpm for 5 minutes to ensure proper dispersion. 10 mL of glutaraldehyde-saturated toluene (GST) was added and mixed for an additional 30 minutes. This step promoted the cross-linking process. To further enhance cross-linking, 1 mL of glutaraldehyde (25% (w / v)) was added to the mixture and reacted for 1 hour, enabling the formation of a stable, interconnected chitosan network within the beads.

[0123] After the cross-linking process was completed, the chito beads were separated by centrifugation and subjected to several washing steps. First, they were washed three times with hexane to remove residual oil, followed by a single wash with acetone to remove excess reactants and impurities. Finally, the beads were washed with deionized water (DW) to ensure cleanliness. After washing, the beads were dried overnight in an oven to remove any remaining moisture, yielding stable chito beads. The dried chito beads were sieved using micro-sieves of 212 μm, 100 μm, and 53 μm to obtain a narrow and uniform particle size.

[0124]

[0125] Characterization of chito beads

[0126] The shape and size of the particles were evaluated using a scanning electron microscope (SEM, JSM-6010LV, Jeol, Japan) at a 5 kV accelerator, and the images were analyzed using ImageJ software. The presence of functional groups in the chitobeads was confirmed using a Bruker-alpha II FT-IR spectrometer (Billerica, MA, US).

[0127] Figures 2a to 2d illustrate SEM images and size distributions of chito beads according to embodiments of the present invention. The chito beads were separated into four groups after sieving, with Figure 2a showing chito beads of 220 μm or more, Figure 2b showing chito beads of 220 μm to 100 μm, Figure 2c showing chito beads of 100 μm to 53 μm, and Figure 2d showing chito beads of 53 μm or less. Referring to FIGS. 2A to 2D, the SEM images of the chitobeads show a spherical shape with a size range of 50 μm to 420 μm, and sieve analysis of the particles showed that 6.71% had a particle size of less than 53 μm (average 32 ± 6.83 μm), 25.43% had a particle size of 53 μm to 100 μm (average 70 ± 4.23 μm), 59.43% had a particle size of 100 μm to 212 μm (average 131 ± 13.90 μm), and 8.43% had a particle size of 212 μm or more (average 283 ± 38.73 μm).

[0128] Figure 3 shows the FT-IR spectra of chitosan and chito beads according to an embodiment of the present invention. The FT-IR spectra of chitosan and chito beads were compared to determine the functional groups used for interaction with organic contaminants and metal ion adsorption. 3300 cm -1 The peak located near 2933 cm is assigned to the typical -OH and -NH stretching vibrations of the polysaccharide backbone. In the chitosan spectrum, it is -1 and 2869cm -1The absorption bands at 1645 cm can be attributed to CH symmetric and asymmetric stretching, respectively. -1 The extended C=O group is due to the acetamide group remaining in chitosan. Also, 1418cm -1 and 1372cm -1 The signals shown in correspond to the CH-CN bond elongation and deformation, respectively. 2943 cm in the chitosan bead spectrum -1 The intensity of the CH symmetric stretching peak increased, which can be associated with the many methyl groups in the graft copolymer. 1630 cm in the FT-IR spectrum of chitosan beads. -1 The peak may be due to the formation of C=N due to the imine reaction between the amino group of chitosan and the aldehyde group of glutaraldehyde by Schiff base reaction. Moreover, 1418 cm -1 The decrease in peak intensity indicated that the amino group was involved in the cross-linking process.

[0129]

[0130] Ion adsorption capacity of chito beads

[0131] Chitosan can adsorb potentially toxic elements due to the presence of amino (-NH2) and hydroxyl (-OH) groups, which serve as coordination and reaction sites. Therefore, the Cu ion adsorption capacity of chitosan beads was evaluated using beads of various sizes. The Cu(II) ion stock solution was prepared by dissolving copper chloride in distilled water at an ion concentration of 1000 ppm (1 g / L). The solution was then diluted to 10 ppm, and chitosan beads of various sizes were added at 0.1 wt%, followed by stirring at 400 rpm for 1 h. The solution was filtered through a 0.45 ㎛ pore size filter, and the concentration of Cu(II) ions was measured using an inductively coupled plasma optical emission spectrometer (ICP-OES 5110, Agilent, CA, USA). The amount of ions adsorbed on the chitosan beads was calculated using the following equation 1: where C o is the initial concentration of ions (mg / ml), Cf is the final concentration of ion (mg / mL), V is the volume of ion solution (mL), and W is the weight of chitobeads (g).

[0132] [Formula 1]

[0133]

[0134] Figure 4 is a graph showing the Cu ion adsorption capacity of chito beads according to an embodiment of the present invention. Referring to Figure 4, when a 0.1 wt% chito bead solution was incubated with a 10 ppm Cu ion solution, it can be observed that the adsorption capacity varies depending on the bead size. This difference is closely related to the surface area to mass ratio, and it can be confirmed that the adsorption capacity increases as the bead diameter decreases. In particular, the smallest beads exhibited the highest adsorption capacity of 5.05 ± 0.77 mg / g.

[0135]

[0136] AFM analysis

[0137] The interfacial force between chitosan and organic contaminants attached to the membrane surface was analyzed using an Innova atomic force microscope (AFM) (Bruker, Santa Barbara, CA, USA). For interfacial force measurements, a commercial SiN probe with 2 μm borosilicate glass particles attached to a cantilever (Novascan, IA, USA) with a spring constant of 0.06 N / m was used. Chitosan was coated on the SiN probe by immersing it in 100 mg / L chitosan dissolved in 5 wt% acetic acid solution for 1 h at room temperature. Meanwhile, organic contaminants were coated on the reverse osmosis membrane using a rinsing method using poly-L-lysine (PLL) chemistry. Briefly, the membrane was contacted with a 0.01 wt% PLL solution for 1 h to make the surface charge positive, and then the membrane was immersed in a 20 mg-C / L HA solution for 1 h. The interaction between the chitosan-coated tip and the organic contaminant-coated membrane was analyzed by combining solutions containing 8.5 mM NaCl and 0.5 mM CaCl2.

[0138] To measure the AFM interaction force, the test solution was dropped on both the fluid cell and the membrane surface. Before measuring the interaction, the system was equilibrated with the chemical properties of the test solution for 30 min. During the AFM operation, an approach / hold speed of 0.5 μm / s with a piezo movement of 0.5 μm was set in force mode. At least 15 force measurements were performed at each position, and four different positions were analyzed. The adhesion energy W(D) (mJ / m) between two opposing planes 2 ) was calculated based on the Derjaguin approximation: F(D) = 2πRW(D), where F(D) is the force between the surfaces and R is the radius sphere of the colloidal AFM cantilever.

[0139] Figures 5a to 5d illustrate the maximum interaction energy distribution per unit area of ​​chitosan and humic acid according to an embodiment of the present invention. To better understand the cleaning mechanism of chito beads, the interaction between chitosan and humic acid (HA) was analyzed using atomic force microscopy (AFM). The bare tip and pristine membrane were coated with chitosan and HA, respectively, to determine the change in interaction. The adhesion between the bare tip and the pristine membrane was 0.201 ± 0.125 mJ / m. 2 For the bare tip and HA-coated membrane, the interaction was 0.145 ± 0.069 mJ / m 2 was weakened. In contrast, the interaction between the chitosan-coated tip and the pristine membrane (0.208 ± 0.094 mJ / m 2 ) was slightly increased compared to the bare tip and pristine membrane. The interaction between chitosan and HA was confirmed to be the strongest among all the interactions measured (0.656 ± 0.150 mJ / m 2 ).

[0140] Chitosan is known to have many reactive functional groups, such as amino, hydroxyl, and N-acetyl groups, in its molecular structure, and thus has various interactions with other compounds, which was also confirmed in the FT-IR spectrum. The extremely strong interactions between chitosan and adsorbate molecules are mainly due to the -NH2 and OH groups in the molecular structure of chitosan. - This occurs because of the presence of HA. In particular, the weakly protonated amines of chitosan have electrostatic attraction with the negatively charged HA and further develop the organic complex. Specifically, the carboxyl group (COOH) and phenol group (OH) of HA interact with the protonated amino group (NH3) of chitosan. +) interact with each other. Since the test pH condition (pH 6.0) was lower than the pKa value of the amino groups of chitosan (pH 6.3), electrostatic attraction mainly contributed to the increase in the interaction between chitosan and HA. On the other hand, the interaction between chitosan and HA also included hydrophobic interactions between the hydrophobic groups of each molecule. Despite the weakening of electrostatic interactions due to the neutral charge of amino groups at alkaline pH, the main adsorption mechanism between HA and chitosan was hydrogen bonding rather than electrostatic interaction, where the carboxyl and phenol groups of HA molecules formed hydrogen bonds with the OH and NH2 groups of chitosan molecules.

[0141] The stronger interaction between HA and chitosan analyzed by AFM in the present invention may contribute to improved cleaning efficiency when chitosan beads are supplemented to the cleaning solution through various interactions such as electrostatic interaction, hydrophobic interaction, cation-π interaction, and hydrogen bonding.

[0142]

[0143] Membrane and fouling formation

[0144] HA stock solution (2 g / L) was prepared by dissolving it in deionized water with gentle mixing for 24 h. Prior to use, the stock solution was filtered through a 0.45 μm cellulose acetate membrane filter (Advantec, Japan). A laboratory-scale cross-flow apparatus was used to perform fouling experiments. A rectangular plate-and-frame membrane cell measuring 7.7 cm × 2.6 cm × 0.3 cm (l × w × h) was used. The retentate was circulated to the feed tank, and the permeate flux was continuously measured using a computer-interfaced balance. The cross-flow speed and operating pressure were adjusted to 10 cm / s and 7 bar, respectively, using a gear pump and a custom-made pressure regulator. The initial water flux was measured under the above operating conditions using 1 L of a foulant-free electrolyte solution containing 8.5 mM NaCl and 0.5 mM CaCl2. For fouling experiments, 20 mg-DOC / L HA was added to the feed tank along with the electrolyte solution and transported until the standardized flow rate reached 0.4.

[0145]

[0146] Membrane cleaning

[0147] After fouling, the solution in the feed tank was replaced with a cleaning solution. 1-Ethyl-3-methylimidazolium acetate (EMIM Ac), which is effective in controlling organic fouling, was used as the cleaning solution. The cleaning efficiency of EMIM Ac was evaluated at neutral pH (0.1 M EMIM Ac) and basic pH (0.05 M NaOH + 0.05 M EMIM Ac). 0.1 wt% of the prepared chitobeads was added to the cleaning solution to enhance the cleaning efficiency through adsorption capacity and mechanical collision. The cleaning solution was in contact with the fouled membrane for 1 h at a cross-flow velocity of 20 cm / s at room temperature. To rinse away the residual cleaning solution, the feed tank was completely replaced with a solution containing 8.5 mM NaCl + 0.5 mM CaCl2. The water flux was measured under the same operating conditions as in the fouling experiment without organic foulants. The initial water flux of the pure membrane and the water flux after cleaning were J0 and J, respectively. c , and the washing efficiency was compared using the following equation 2.

[0148] [Formula 2]

[0149]

[0150]

[0151] Analysis of surface morphology after cleaning

[0152] The surfaces of pristine membranes, HA-contaminated membranes, membranes cleaned with detergent only, and membranes cleaned with detergent containing chito beads (D = 32 μm) were observed using scanning electron microscopy and atomic force microscopy. The scanning electron microscope was operated at a 5 kV accelerator. The same AFM equipment as described above was used, and a commercial Sharp microlever probe (MSNL-10, Bruker, Santa Barbara, CA, USA) was used in contact mode. Specifically, a rectangular tip with a spring constant of 0.02 N / m was used to scan a 10 μm x 10 μm area on the membrane surface. The root mean square of the profile height deviation from the mean line was measured at least five times for each sample, and the average was presented.

[0153]

[0154] Analysis of the cleaning efficiency of chito beads

[0155] Chitosan has been widely used in adsorption applications because it can adsorb organic species and metal ions with various interactions. However, there has been no study on the application of chitosan beads to control membrane fouling using organic contaminants. It can be argued that when chitosan beads are used as a cleaning solution, they cause particulate fouling rather than acting as a cleaning agent. However, in the present invention, it is expected that chitosan beads can improve cleaning efficiency through chemical adsorption of organic substances and metal ions and mechanical separation of contaminants from the membrane surface. Therefore, chitosan beads were added to a chemical cleaning solution to determine whether chitosan beads can increase the efficiency of chemical cleaning. To determine the effect of chitosan beads on cleaning efficiency, chitosan beads were added to 0.1 M EMIM or 0.05 M EMIM + 0.05 M NaOH solutions.

[0156] Natural organic matter (NOM) is ubiquitous in surface waters due to the decomposition of microorganisms, animals, and plants. Among NOM, HA has been widely considered a model foulant not only because it is abundant in feedwater for membrane-based water treatment processes but also because it acts as a "cement" during the formation of a fouling layer when combined with inorganic clay. Therefore, the fouling layer of the present invention was developed using HA as a model foulant. The HA-contaminated membrane was induced to HA fouling until a recovery rate of 50% was achieved, after which it was cleaned with or without pH adjustment. The decrease and recovery of water flux due to HA fouling and cleaning, as well as the cleaning efficiency under each condition, were examined.

[0157] Figures 6a and 6b show the flux recovery rate of the humic acid contaminated film according to an embodiment of the present invention. Figure 6a shows the flux recovery rate at neutral pH, and Figure 6b shows the flux recovery rate at alkaline pH. The cleaning efficiency of chito beads of various sizes in the presence of 0.1 M EMIM was 70 μm chito beads (86.9 ± 1.3%), 32 μm chito beads (84.0 ± 3.1%), 283 μm chito beads (82.3 ± 1.4%), 131 μm chito beads (77.8 ± 1.4%), and EMIM alone (73.5 ± 0.6%). Compared to cleaning using an EMIM-only solution, chito beads were found to improve the cleaning efficiency for HA at all sizes (p value < 0.05). The increased cleaning efficiency when supplemented with chitosan beads compared to EMIM alone can be explained by the various chemical interactions between chitosan and HA analyzed by AFM and the mechanical collisions between chitosan beads and precipitated contaminants, which led to the detachment of the foulant layer from the membrane surface. Of course, it is highly likely that the strong cation-π interaction between the positively charged primary amine groups of chitosan beads and aromatic contaminants contributed to the foulant removal. Under elevated pH conditions, the cleaning efficiency was, in order, 32 μm chitosan beads (100.1 ± 1.6%), 70 μm chitosan beads (98.4 ± 2.5%), EMIM alone (79.9 ± 3.3%), 131 μm chitosan beads (79.8 ± 2.4%), 283 μm chitosan beads (78.3 ± 3.8%), and NaOH alone (68.8 ± 1.5%). Under alkaline pH conditions, the cleaning efficiency of EMIM-containing solutions increased under all test conditions compared to a NaOH-only cleaning solution (p value < 0.05), which was attributed to the synergistic cleaning effect of the ionic liquid and sodium hydroxide. Specifically, the ionic liquid was shown to induce swelling of the contaminated layer, while the sodium hydroxide hydrolyzed the organic matter in the contaminated layer.Under elevated pH conditions, the addition of chitobeads of relatively larger sizes (131 μm and 283 μm) was not effective in improving the washing efficiency compared to the EMIM+NaOH solution (p values ​​> 0.05). On the other hand, the washing efficiency of the washing solution using chitobeads of smaller sizes (32 μm and 70 μm) was significantly increased compared to the EMIM+NaOH solution (p values ​​< 0.05).

[0158] The adsorption capacity of chitosan is known to decrease dramatically as the pH of the solution increases, compared to acidic and neutral pH conditions. Despite the decrease in adsorption capacity, chitosan beads are hypothesized to swell and effectively disrupt the hydrolyzed contaminant layer through mechanical collisions with ionic liquids and sodium hydroxide.

[0159] Chitosan particles have been used in water treatment processes for the adsorption of metals such as Pb(II), Cu(II), and Hg(II), as well as antimicrobial and antibacterial agents. Furthermore, chitosan particles have been utilized as biocoagulants to remove solids and organic substances present in wastewater and seawater. However, no study has applied chitosan bead particles to control fouling of membranes developed using humic acid. In the present invention, under specific operating conditions with increased cross-flow velocity of the cleaning solution, chitosan beads precipitated on the membrane surface, thereby enhancing cleaning efficiency instead of causing particulate fouling. Adding chitosan beads to the cleaning solution could enhance the mechanical collision between chitosan beads and contaminants on the membrane surface, making it even more effective when used in a membrane bioreactor.

[0160]

[0161] Characterization of the membrane surface after cleaning with chito beads

[0162] Figure 7 is a photographic image of a membrane according to an embodiment of the present invention. Figure 7 shows, from top to bottom, photographic images of a clean membrane, an HA-contaminated membrane, a membrane cleaned with NaOH + EMIM, and a membrane cleaned with chito beads (D = 32 μm) and NaOH + EMIM. Referring to Figure 7, in the photographic image of the HA-contaminated membrane, a fouling layer formed by HA was clearly observed compared to the original membrane. On the other hand, the photographic images of the membranes washed with a cleaning solution with or without chito beads became similar to the original membrane. However, since the information provided through the photographic images was limited, additional analysis was performed.

[0163] Figure 8 is a SEM image showing the surface morphology of a membrane according to an embodiment of the present invention. Figure 8 shows, from top to bottom, SEM images of a clean membrane, an HA-contaminated membrane, a membrane cleaned with NaOH+EMIM, and a membrane cleaned with chito beads (D=32 μm) and NaOH+EMIM. In the SEM image of the clean membrane, the unique characteristic of the polyamide layer, the ridge and valley structure, was clearly observed. In contrast, in the case of the HA-contaminated membrane, the SEM image showed that HA molecules were deposited on the membrane surface together with ionic species present in the feed solution, such as NaCl and CaCl2. After washing with the NaOH+EMIM solution, chito beads, and NaOH+EMIM solution, the ridge and valley structure of the polyamide active layer reappeared, confirming the efficient washing of the HA-contaminated layer.

[0164] Figure 9 shows the roughness of membranes according to an embodiment of the present invention. Figure 9 shows the roughness of a clean membrane, a HA-contaminated membrane, a membrane cleaned with NaOH + EMIM, and a membrane cleaned with chito beads (D = 32 μm) and NaOH + EMIM, in order from the top. The average RMS (root mean square) values ​​of Rq of the original membrane surface and the HA-contaminated surface were 45 ± 1 nm and 101 ± 27 nm, respectively. Previously, it was shown that a fouling layer created by organic substances on a reverse osmosis (RO) membrane increases the surface roughness. When the membrane was cleaned with an EMIM + NaOH cleaning solution, the surface roughness was 69 ± 8 nm, whereas the membrane cleaned with chito beads in an EMIM + NaOH solution showed a surface roughness of 55 ± 8 nm. As the surface roughness of the membrane washed with chito beads in the EMIM+NaOH solution approaches that of the original membrane, it can be seen that chito beads improve the washing efficiency of the EMIM+NaOH solution.

[0165] Figure 10 shows the results of SEM-EDS analysis of a membrane according to an embodiment of the present invention. To better quantify the cleaning efficiency and understand the cleaning mechanism of the chito beads, elements present on the membrane surface were analyzed through SEM-EDS. Sodium and calcium were added as electrolytes to control the ionic strength of the feed solution during the fouling experiment. Specifically, calcium ions were Ca 2+It is known to form a complex with HA through crosslinking and further develop a dense fouling layer on the membrane surface. In the case of the clean membrane, sodium and calcium were not detected in the SEM-EDS analysis. On the other hand, in the HA-contaminated membrane, sodium and calcium were detected at 0.14±0.05 wt% and 0.46±0.03 wt%, respectively. In the case of the cleaning solution alone without adding chitosan beads, sodium was analyzed at 0.22±0.07 wt% and calcium at 0.02±0.03 wt%. When chitosan beads were added to the cleaning solution, the wt% of sodium and calcium were below the detection limit of the SEM-EDS analysis. Consequently, it can be seen that the ions present in the fouling layer formed a complex with the amine group of chitosan and were adsorbed to the chitosan beads.

[0166]

[0167] The purpose of the present invention is to utilize chitosan-based beads as an additive in chemical cleaning solutions to control irreversible fouling of reverse osmosis membranes. The cleaning efficiency of chitosan beads of various sizes, ranging from 32 μm to 283 μm, was evaluated against HA-fouled membranes under neutral and alkaline pH conditions. The addition of chitosan beads improved cleaning efficiency at neutral pH compared to the cleaning solution alone. Under alkaline pH conditions, the addition of smaller chitosan beads (32 μm and 70 μm) significantly increased cleaning efficiency and restored the water flux to its initial value. The interaction energy between the chitosan-coated tip and the HA-fouled membrane was found to be significantly stronger than that between the bare tip and the HA-fouled membrane. This strong interaction between chitosan and HA arises not only from electrostatic interactions but also from hydrophobic interactions and hydrogen bonding. Utilizing chitosan beads as a solution for irreversible membrane fouling holds great promise through the chemical adsorption of organics and the mechanical separation of foulants from the membrane surface. The present invention may extend the use of chitobeads as an essential component of membrane chemical cleaning solutions to control membrane fouling in other membrane processes.

[0168]

[0169] Although the embodiments have been described above, those skilled in the art will appreciate that various technical modifications and variations can be applied based on the above. For example, appropriate results can still be achieved even if the described techniques are performed in a different order than described, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents.

[0170] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims described below.

Claims

1. Containing kito beads, Composition for cleaning membranes.

2. In paragraph 1, The above-mentioned chitosan beads have a diameter of 1 ㎛ to 500 ㎛. Composition for cleaning membranes.

3. In paragraph 1, The above-mentioned chito beads are 0.01 wt% to 10 wt% of the composition, Composition for cleaning membranes.

4. In paragraph 1, The above-mentioned chitobeads have an ion adsorption capacity of 1 mg / g to 10 mg / g. Composition for cleaning membranes.

5. In paragraph 1, which further comprises an ionic liquid, Composition for cleaning membranes.

6. In paragraph 5, The above ionic liquid is 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium tetraborate, 1-vinyl-3ethylimidazoliumbis(trifluoromethylsulfonyl)amide, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-octyl-3-methylimidazolium chloride, and 1-octyl-3-methylimidazolium Containing at least one selected from the group consisting of bromide (1-octyl-3-methylimidazolium bromide), Composition for cleaning membranes.

7. In paragraph 5, The ionic liquid is 0.01 wt% to 5 wt% of the composition, Composition for cleaning membranes.

8. In paragraph 1, The above separation membrane is a reverse osmosis membrane used in a water treatment process. Composition for cleaning membranes.

9. In paragraph 1, The above composition has a pH of 4 to 14, Composition for cleaning membranes.

10. In paragraph 1, The above composition is for cleaning irreversible contaminants attached to the separation membrane. Composition for cleaning membranes.

11. In paragraph 10, The above contaminant comprises at least one selected from the group consisting of humic acid, alginic acid, peptide, heavy metal, metal ion, microorganism, microbial biofilm and extracellular polymer (EPS). Composition for cleaning membranes.

12. In paragraph 10, The flux recovery rate after the above cleaning is 75% or more, Composition for cleaning membranes.

13. In paragraph 10, The surface roughness of the separation membrane after the above cleaning is such that the increase rate is 30% or less compared to the surface roughness of the separation membrane before the contamination source is attached. Composition for cleaning membranes.

14. A step of preparing a mixed solution by dispersing a chitosan solution in an oil solution; A step of crosslinking by adding a crosslinking agent to the above mixed solution; Washing step after centrifugation; and a step of drying to obtain chito beads; Method for producing a composition for cleaning a membrane.

15. In paragraph 14, The above chitosan solution has a chitosan content of 2 wt% to 10 wt%, The weight ratio of the chitosan solution and the oil solution is 1:2 to 1:

7. Method for producing a composition for cleaning a membrane.

16. In paragraph 14, After the step of obtaining the above chito beads, the step of mixing the chito beads and the ionic liquid is further included. Method for producing a composition for cleaning a membrane.

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