A cleaning agent for plant extraction processing membranes and a method of using the same

Abstract

The present application belongs to the field of cleaning agent, and particularly relates to a cleaning agent for plant-extracted processing film and a use method thereof. The cleaning agent comprises the following components by weight: 30-60 parts of alkaline cleaning agent, 0.1-5 parts of surfactant, and 1-20 parts of alkaline enzyme protein cleaning agent; and the cleaning agent is adjusted to a pH value of 11.5-12 by a buffer. The cleaning agent can comprehensively and effectively clean the film material through alkaline treatment and enzyme treatment, is suitable for cleaning and removing various types of film material pollutants, and can greatly exert the characteristics of the mild and high cleaning capacity of the cleaning agent in combination with the specific use method of the present application, so that almost complete non-damaging cleaning of the film material is achieved.

Description

Technical Field

[0001] This invention belongs to the field of cleaning agents, and particularly relates to a cleaning agent for plant extract-treated membranes, and its method of use. Background Technology

[0002] Membrane separation technology offers advantages over other processes in separating plant extracts, characterized by low energy consumption and high separation precision. However, membrane fouling is the most significant hurdle to overcome in its widespread application in plant-based material separation. In plant extraction processes using membrane separation, raw materials undergo mechanical and high-temperature treatments before entering the membrane separation system. During this process, plant cells in the feed solution are disrupted and divided, allowing the target extract to enter for subsequent extraction and concentration. However, the ruptured plant cells also introduce a large amount of residual cell wall fibrous material, cell proteins, and polysaccharides. These residual cells cause irreversible membrane fouling during the extraction concentration process, reducing membrane permeability and necessitating system shutdowns for maintenance, thus impacting the concentration efficiency of the production process.

[0003] Typically, this type of membrane fouling is controlled primarily with cleaning agents formulated with strong alkalis, which are effective at a pH of approximately 12-13. Strong alkalis denature proteins, loosening the bond between the fouling layer and the membrane surface, thus achieving a cleaning effect. However, strong alkaline cleaning agents also accelerate membrane aging, reduce membrane strength, enlarge membrane pores, and decrease separation efficiency, thereby shortening the membrane's lifespan. Furthermore, they present problems such as long cleaning times, impacting production efficiency.

[0004] However, most existing cleaning agents also have drawbacks. For example, common alkaline cleaning agents are ineffective at cleaning cell wall cellulose. For instance, protease-containing cleaning agents like those specified in CN 109718670A require an alkaline environment of 10.5-11. The combined use of alkali in the cleaning process leads to instability and inactivation of the protein components during preparation, resulting in limited cleaning effectiveness. Furthermore, they are not specifically targeted at cell wall cellulose contamination of membranes in plant extract separation applications, resulting in poor cleaning performance. The effectiveness of conventional proteolytic enzyme cleaning agents is easily affected by environmental factors, and enzymes may become inactivated during use.

[0005] Therefore, it is essential to develop a membrane cleaning agent that is gentle on the membrane and highly efficient. Summary of the Invention

[0006] To address the issues of existing cleaning agents having poor cleaning effects, unstable cleaning effects, or causing damage to membrane materials, this invention provides a cleaning agent for plant extract-treated membranes, as well as a method for using the cleaning agent.

[0007] The purpose of this invention is:

[0008] 1. It can achieve thorough and effective cleaning of the plant extract treatment membrane;

[0009] Second, ensure that the cleaning agent has good stability;

[0010] Third, ensure that the cleaning agent effectively protects the plant extract treatment membrane during the cleaning process to avoid damage.

[0011] To achieve the above objectives, the present invention adopts the following technical solution.

[0012] A cleaning agent for plant extract treatment membranes,

[0013] The cleaning agent comprises the following components in parts by weight:

[0014] The cleaning agent comprises 30-60 parts by weight of alkaline cleaning agent, 0.1-5 parts by weight of surfactant, and 1-20 parts by weight of alkaline enzyme protein cleaning agent; the pH of the cleaning agent is adjusted to 11.5-12 with a buffer.

[0015] In this invention, a weakly alkaline cleaning agent combined with a surfactant can decompose and remove common small-molecule contaminants, while the combination with an alkaline enzyme-protein cleaning agent can remove some large-molecule contaminants such as cellulose. Simultaneously, the use of an alkaline enzyme-protein cleaning agent in conjunction with a weakly alkaline cleaning agent, and the use of a buffer to control the pH value and maintain relative stability during use, ensures good chemical stability of the overall cleaning agent, especially preventing the alkaline enzyme-protein cleaning agent from becoming deactivated. The buffers commonly used in this invention are any one or more of ammonium citrate, sodium citrate, and sodium carbonate; however, the use of other conventional pH buffers is not excluded.

[0016] Preferably, the alkaline cleaning agent comprises a base metal salt of tripolyphosphate and / or an alkali metal salt of ethylenediaminetetraacetic acid and / or an alkali metal hydroxide.

[0017] The surfactant is sodium dodecyl sulfonate and / or dodecylphenol polyoxyethylene ether and / or sodium polystyrene sulfonate.

[0018] The alkaline cleaners mentioned above are relatively mild, non-alkaline cleaners that have a good basic cleaning effect on plant extract-treated membranes. When used with surfactants, they can produce effective foaming cleaning, washing away weakly bound adhering contaminants, as well as some oil and other types of contaminants. They can also produce relatively excellent removal effects on other contaminant components besides macromolecular compounds.

[0019] As a preferred option

[0020] The alkaline enzyme protein cleaning agent includes an enzyme-containing agent and a stabilizer;

[0021] The enzyme-containing agent includes α-chymotrypsin and / or N-acetylmuraminase and / or W146 subtilisin.

[0022] The stabilizer is fatty alcohol polyvinyl ether and / or sodium borate;

[0023] The mass ratio of the enzyme-containing agent to the stabilizer is 1:(0.01~0.1).

[0024] The enzyme-containing agents used in this invention are specifically selected to target large molecular contaminants that may adhere to and are difficult to remove easily during the use of common plant extract-treated membranes. Among them, proteases mainly target plant proteins, which can clean protein contaminants on the membrane surface and avoid the use of strong alkaline cleaning ingredients, thus reducing damage to the membrane. Cellular plasmin, on the other hand, targets and removes cellulose contaminants, improving the cleaning effect.

[0025] As a preferred option

[0026] The stabilizer contains at least sodium borate.

[0027] The stabilizer used in this invention contains at least sodium borate because it can undergo strong hydration with water to reduce the content of free water, stabilize alkaline proteases, inhibit the autolysis of the enzyme-containing agent used in this invention in a slightly alkaline environment, and significantly improve the stability of the enzyme-containing agent.

[0028] As a preferred option

[0029] The cleaning agent also includes a penetrant;

[0030] The amount of the penetrant used is ≤10 parts by weight.

[0031] The penetrant selected is fatty alcohol polyoxyethylene ether, which has good affinity with the hydrophilic groups on the membrane surface. This can accelerate the penetration and cleaning of the cleaning agent components on the membrane surface, improve cleaning efficiency, and reduce damage to the membrane.

[0032] As a preferred option

[0033] The cleaning agent also includes a dispersant;

[0034] The amount of the dispersant is ≤10 parts by weight.

[0035] The use of dispersants is also very important in this invention. Sodium polyacrylate is specifically chosen as a dispersant because its side chains contain a large number of carboxylate groups, which can chelate with calcium and magnesium. These numerous active groups can adsorb and fix onto the crystal surface, causing lattice distortion and preventing the formation of crystalline particles from the plant-based liquid residue on the membrane surface, thus weakening the cleaning effect.

[0036] Instructions for using a cleaning agent for plant extract treatment membranes.

[0037] The method includes:

[0038] 1) Dissolve the cleaning agent components of the plant extract-treated membrane, excluding alkaline enzyme protein cleaning agent and buffer, in warm water at ≥35℃ to prepare a cleaning base solution with a concentration of 0.3-0.5wt%. Adjust the pH of the cleaning base solution to 11.5-12 with buffer.

[0039] 2) Add alkaline enzyme protein cleaning agent to the cleaning solution to prepare a cleaning agent for the plant extract treatment membrane. Heat the solution to 40-50℃ and clean the plant extract separation membrane for 45-90 minutes. After cleaning, rinse with water until the pH of the washing solution is 6-7 to complete the cleaning of the plant extract separation membrane.

[0040] For the cleaning agent of this invention, it is necessary to control its liquid preparation and temperature when using it, but the actual use method is still very simple and efficient.

[0041] As a preferred option

[0042] During the cleaning process described in step 2):

[0043] The plant extract separation membrane was cleaned using a high-pressure washer, with the cleaning pressure controlled at 3–6 bar and the cleaning time at 45–60 min.

[0044] This is a common high-pressure cleaning method for membrane materials, which can be widely applied to the effective cleaning of a large number of membrane materials.

[0045] As a preferred option

[0046] Step 2) describes a cleaning process using gradient pressure cleaning, specifically:

[0047] Four pressure zones are set in sequence: the first pressure zone, the second pressure zone, the third pressure zone, and the fourth pressure zone.

[0048] The four pressure zones are separated by capillary plates;

[0049] The pressure in the first pressure zone, the second pressure zone, the third pressure zone and the fourth pressure zone decreases step by step, and the cleaning agent of the plant extract treatment membrane flows through the first pressure zone, the second pressure zone, the third pressure zone and the fourth pressure zone in sequence.

[0050] The plant extract separation membrane is sequentially placed in the first pressure zone, the second pressure zone, and the third pressure zone for 25–30 minutes for cleaning.

[0051] The above method is a specific cleaning method developed for the cleaning agent of this invention. Its purpose is to achieve non-destructive cleaning of the plant extract-treated membrane. In conventional processing, to ensure thorough cleaning, a high cleaning pressure is required to clean the pores of the plant extract-treated membrane and restore its original filtration capacity. However, for the specific cleaning agent of this invention, the above method uses a first pressure zone to a fourth pressure zone set sequentially from top to bottom. The flow of the cleaning agent is controlled by the pressure difference between each zone and the capillary plate. Simultaneously, the pressure is controlled in zones to sequentially achieve initial pore cleaning, cleaning of surface contaminants, and deep pore cleaning.

[0052] As a preferred option

[0053] The control pressure within the first pressure zone is 1.20–1.50 bar;

[0054] The control pressure in the second pressure zone is 0.95–1.05 bar;

[0055] The control pressure in the third pressure zone is 0.65–0.80 bar;

[0056] The control pressure in the fourth pressure zone is 0.25–0.35 bar.

[0057] In the above method, a relatively high pressure is used in the first pressure zone to introduce the cleaning agent into the pores for initial cleaning, achieving preliminary "pore enlargement" while avoiding damage to the pores caused by high pressure. The second pressure zone focuses on cleaning the membrane surface and partially removing contaminants that were initially treated in the first pressure zone, complementing the first pressure zone for a more thorough surface cleaning. The third pressure zone uses a negative pressure working space relative to normal pressure because after treatment in the first and second pressure zones, microbubbles that are difficult to remove appear in the membrane pores. Conventional high pressure methods can remove these microbubbles for direct and effective deep cleaning, but this carries the risk of damaging the membrane. In contrast, the cleaning agent of this invention has good fluidity and permeability. The negative pressure condition removes microbubbles and allows the cleaning agent to effectively penetrate back into the pores for deep and thorough cleaning.

[0058] The beneficial effects of this invention are:

[0059] The cleaning agent of this invention can thoroughly and effectively clean membrane materials through alkali and enzyme treatment. It is suitable for cleaning and removing various types of membrane material contaminants. When used in accordance with the specific application method of this invention, the cleaning agent's mild and high cleaning power can be maximized, achieving almost completely non-destructive cleaning of the membrane material. Detailed Implementation

[0060] The present invention will be further described clearly and in detail below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0061] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0062] Example 1

[0063] A cleaning agent for plant extract treatment membranes has the following formulation:

[0064] The cleaning agent is prepared as follows: 45 parts by weight of sodium tripolyphosphate, 3 parts by weight of sodium dodecyl sulfonate, 5 parts by weight of α-chymotrypsin, 5 parts by weight of N-acetylmuraminase, 0.5 parts by weight of sodium borate, 5 parts by weight of fatty alcohol polyoxyethylene ether, and 5 parts by weight of sodium polyacrylate;

[0065] Sodium tripolyphosphate, sodium dodecyl sulfonate, fatty alcohol polyoxyethylene ether, and sodium polyacrylate were dissolved in deionized water at 40°C and stirred until homogeneous to prepare a cleaning base solution with a concentration of 0.35 wt%. The pH of the cleaning base solution was adjusted to 11.5 with sodium citrate. Then, α-chymotrypsin, N-acetylmuraminase, and sodium borate were added to the cleaning base solution and stirred until homogeneous for later use.

[0066] Example 2

[0067] A cleaning agent for plant extract treatment membranes has the following formulation:

[0068] 30 parts by weight of sodium hydroxide, 0.5 parts by weight of dodecylphenol polyoxyethylene ether, 1 part by weight of W146 subtilisin, 1 part by weight of N-acetylmuraminase, 0.01 parts by weight of sodium borate, 0.03 parts by weight of fatty alcohol polyoxyethylene ether, 1 part by weight of fatty alcohol polyoxyethylene ether, and 1 part by weight of sodium polyacrylate.

[0069] The cleaning agent is prepared as follows:

[0070] Sodium hydroxide, dodecylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and sodium polyacrylate were dissolved in deionized water at 40°C and stirred until homogeneous to prepare a cleaning base solution with a concentration of 0.5 wt%. The pH of the cleaning base solution was adjusted to 11.5 with sodium citrate. Then, W146 subtilisin, N-acetylmuraminase, fatty alcohol polyvinyl ether, and sodium borate were added to the cleaning base solution and stirred until homogeneous before use.

[0071] Example 3

[0072] A cleaning agent for plant extract treatment membranes has the following formulation:

[0073] Sodium ethylenediaminetetraacetate 60 parts by weight, sodium polystyrene sulfonate 5 parts by weight, α-chymotrypsin 10 parts by weight, N-acetylmuraminase 8 parts by weight, sodium borate 1.5 parts by weight, fatty alcohol polyoxyethylene ether 10 parts by weight, sodium polyacrylate 10 parts by weight.

[0074] The cleaning agent is prepared as follows:

[0075] Sodium ethylenediaminetetraacetate, sodium polystyrene sulfonate, fatty alcohol polyoxyethylene ether, and sodium polyacrylate were dissolved in deionized water at 40°C and stirred until homogeneous to prepare a cleaning base solution with a concentration of 0.35 wt%. The pH of the cleaning base solution was adjusted to 11.5 with sodium citrate. Then, α-chymotrypsin, N-acetylmuraminase, and sodium borate were added to the cleaning base solution and stirred until homogeneous for later use.

[0076] Comparative Example 1

[0077] The ingredients and preparation method are the same as in Example 1, except that no enzyme-containing agent is added.

[0078] Comparative Example 2

[0079] The ingredients and preparation method are the same as in Example 2, except that no enzyme-containing agent is added.

[0080] Comparative Example 3

[0081] The ingredients and preparation method are the same as in Example 3, except that no enzyme-containing agent is added.

[0082] Application Example 1

[0083] The cleaning agent for the plant extract-treated membrane prepared in Example 1 was heated to 45°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure cleaner. The cleaning pressure was controlled at 5 bar, and the cleaning time was 50 minutes.

[0084] The cleaning agent for the plant extract-treated membrane prepared in Example 2 was heated to 50°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure cleaner. The cleaning pressure was controlled at 6 bar, and the cleaning time was 45 minutes.

[0085] The cleaning agent for the plant extract-treated membrane prepared in Example 3 was heated to 40°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 3 bar, and the cleaning time was 60 minutes.

[0086] The cleaning agent for the plant extract-treated membrane prepared in Comparative Example 1 was heated to 45°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 5 bar, and the cleaning time was 50 minutes.

[0087] The cleaning agent for the plant extract-treated membrane prepared in Comparative Example 2 was heated to 50°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 6 bar, and the cleaning time was 45 minutes.

[0088] The cleaning agent for the plant extract-treated membrane prepared in Comparative Example 3 was heated to 40°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 3 bar, and the cleaning time was 60 minutes.

[0089] The LMH of the nanofiltration membrane before and after the above cleaning was characterized by the following test results.

[0090] Example 1 Example 2 Example 3 Before cleaning (LMH) 18 22 12 After cleaning (LMH) 68 45 65 Cleaning change rate 3.7 2.0 5.4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Before cleaning (LMH) 10 23 16 After cleaning (LMH) 12 25 30 Cleaning change rate 1.17 1.11 1.86

[0091] The above comparison clearly shows that the addition of enzymes has a significant difference in the cleaning effect on the membrane material. The cleaning agent of the present invention with added enzymes has a much better cleaning effect on the membrane material than the control group without added enzymes.

[0092] Comparative Example 4

[0093] The ingredients and preparation method are the same as in Example 1, except that no penetrant and dispersant are added.

[0094] Comparative Example 5

[0095] The ingredients and preparation method are the same as in Example 2, except that no penetrant and dispersant are added.

[0096] Comparative Example 6

[0097] The ingredients and preparation method are the same as in Example 3, except that no penetrant and dispersant are added.

[0098] Application Example 2

[0099] The cleaning agent for the plant extract-treated membrane prepared in Example 1 was heated to 45°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure cleaner. The cleaning pressure was controlled at 5 bar, and the cleaning time was 50 minutes.

[0100] The cleaning agent for the plant extract-treated membrane prepared in Example 2 was heated to 50°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure cleaner. The cleaning pressure was controlled at 6 bar, and the cleaning time was 45 minutes.

[0101] The cleaning agent for the plant extract-treated membrane prepared in Example 3 was heated to 40°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 3 bar, and the cleaning time was 60 minutes.

[0102] The cleaning agent for the plant extract-treated membrane prepared in Comparative Example 4 was heated to 45°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 5 bar, and the cleaning time was 50 minutes.

[0103] The cleaning agent for the plant extract-treated membrane prepared in Comparative Example 5 was heated to 50°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 6 bar, and the cleaning time was 45 minutes.

[0104] The cleaning agent for the plant extract-treated membrane prepared in Comparative Example 6 was heated to 40°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 3 bar, and the cleaning time was 60 minutes.

[0105] The LMH of the nanofiltration membrane before and after the above cleaning was characterized by the following test results.

[0106] Example 1 Example 2 Example 3 Before cleaning (LMH) 22 21 19 1 hour after cleaning (LMH) 64 49 60 2 hours after cleaning (LMH) 78 62 83 Comparative Example 4 Comparative Example 5 Comparative Example 6 Before cleaning (LMH) 18 22 12 1 hour after cleaning (LMH) 30 26 34 2 hours after cleaning (LMH) 50 45 57

[0107] As can be seen from the above test results, the addition of penetrant and dispersant to the technical solution of the present invention has a significant impact on the cleaning effect, and can more effectively achieve continuous cleaning of pollutants in a short time, and shorten the time required for cleaning to restore flux.

[0108] Comparative Example 7

[0109] The ingredients and preparation method are the same as in Example 1, except that no enzyme stabilizer is added.

[0110] Comparative Example 8

[0111] The ingredients and preparation method are the same as in Example 2, except that no enzyme stabilizer is added.

[0112] Comparative Example 9

[0113] The ingredients and preparation method are the same as in Example 3, except that no enzyme stabilizer is added.

[0114] Application Example 3

[0115] Before conducting the experiment in this application example, the pH value was adjusted to 12 based on the original cleaning agent used for the plant extract treatment membrane.

[0116] The cleaning agent for the plant extract-treated membrane prepared in Example 1 was heated to 45°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure cleaner. The cleaning pressure was controlled at 5 bar, and the cleaning time was 50 minutes.

[0117] The cleaning agent for the plant extract-treated membrane prepared in Example 2 was heated to 50°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure cleaner. The cleaning pressure was controlled at 6 bar, and the cleaning time was 45 minutes.

[0118] The cleaning agent for the plant extract-treated membrane prepared in Example 3 was heated to 40°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 3 bar, and the cleaning time was 60 minutes.

[0119] The cleaning agent for the plant extract-treated membrane prepared in Comparative Example 7 was heated to 45°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 5 bar, and the cleaning time was 50 minutes.

[0120] The cleaning agent for the plant extract-treated membrane prepared in Comparative Example 8 was heated to 50°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 6 bar, and the cleaning time was 45 minutes.

[0121] The cleaning agent for the plant extract-treated membrane prepared in Comparative Example 9 was heated to 40°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 3 bar, and the cleaning time was 60 minutes.

[0122] The LMH of the nanofiltration membrane before and after the above cleaning was characterized by the following test results.

[0123] Example 1 Example 2 Example 3 Before cleaning (LMH) 19 29 14 After cleaning (LMH) 73 87 87 Cleaning change rate 3.8 3.0 6.1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Before cleaning (LMH) 18 23 13 After cleaning (LMH) 53 51 45 Cleaning change rate 2.8 2.2 3.3

[0124] Under enhanced alkaline conditions, it is evident that the addition of an enzyme stabilizer significantly impacts the effectiveness of the cleaning agent. Existing plant extract-treated membranes typically retain some acidity or alkalinity after use, thus affecting the actual cleaning agent's performance. In particular, some membrane materials, when strongly alkaline, significantly weaken the cleaning agent's effectiveness. However, the addition of an enzyme stabilizer greatly improves the pH tolerance of the cleaning agent of this invention, resulting in superior performance.

[0125] Application Example 4

[0126] Record the magnesium sulfate removal rate of each group of original membrane materials.

[0127] Set up a mild treatment experimental group:

[0128] The system is divided into four pressure zones from top to bottom: a first pressure zone, a second pressure zone, a third pressure zone, and a fourth pressure zone. Pressure is controlled between each zone, and each pressure zone is separated by a capillary plate. The membrane material to be cleaned is placed on the capillary plate, and a 1cm thick square frame is placed under the edge of the membrane material to create a gap between the membrane material and the capillary plate. Cleaning agent is poured into the first, second, and third pressure zones to a height of 2cm, and cleaning agent is slowly and continuously added to the first pressure zone to keep the liquid level between 2.0 and 2.5cm.

[0129] The membrane material to be cleaned is placed in the first pressure zone, the second pressure zone, and the third pressure zone in sequence for cleaning;

[0130] The membrane material to be cleaned is the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system (i.e., using the original contaminated membrane material, the same below);

[0131] in:

[0132] The test group cleaned with the cleaning agent of Example 1 had the following settings: the pressure in the first pressure zone was 1.35 bar, the pressure in the second pressure zone was 1.00 bar, the pressure in the third pressure zone was 0.70 bar, and the pressure in the fourth pressure zone was 0.30 bar. The cleaning time for the membrane material to be cleaned in the first, second, and third pressure zones was 25 minutes.

[0133] The test group cleaned with the cleaning agent of Example 2 had the following settings: the pressure in the first pressure zone was 1.50 bar, the pressure in the second pressure zone was 0.95 bar, the pressure in the third pressure zone was 0.65 bar, and the pressure in the fourth pressure zone was 0.25 bar. The cleaning time for the membrane material to be cleaned in the first, second, and third pressure zones was 30 minutes.

[0134] In the test group using the cleaning agent of Example 3, the pressure in the first pressure zone was set to 1.20 bar, the pressure in the second pressure zone was set to 1.05 bar, the pressure in the third pressure zone was set to 0.80 bar, and the pressure in the fourth pressure zone was set to 0.35 bar. The cleaning time for the membrane material to be cleaned in the first, second, and third pressure zones was 25 minutes.

[0135] Set up a routine immersion test group:

[0136] The membrane material to be cleaned was immersed in the cleaning agents prepared in Examples 1, 2 and 3, as well as a commercially available strong alkaline cleaning agent (pH value 13) for 240 hours.

[0137] Set up a high-pressure cleaning test group:

[0138] The cleaning agent for the plant extract-treated membrane prepared in Example 1 was heated to 45°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure cleaner. The cleaning pressure was controlled at 5 bar, and the cleaning time was 50 minutes.

[0139] The cleaning agent for the plant extract-treated membrane prepared in Example 2 was heated to 50°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure cleaner. The cleaning pressure was controlled at 6 bar, and the cleaning time was 45 minutes.

[0140] The cleaning agent for the plant extract-treated membrane prepared in Example 3 was heated to 40°C, and the contaminated polyamide nanofiltration membrane in the tea polyphenol concentration system was cleaned under high pressure using a high-pressure washer. The cleaning pressure was controlled at 3 bar, and the cleaning time was 60 minutes.

[0141] The magnesium sulfate removal rates of the original membrane materials and the magnesium sulfate removal rates after cleaning were tested, recorded, and compared. See below.

[0142]

[0143] As shown in the table above, the gentle cleaning method ensures thorough and effective cleaning of the membrane material while avoiding damage, resulting in separation performance almost identical to the original membrane material after cleaning. The conventional immersion washing group showed slightly inferior cleaning effect compared to the high-pressure washing group, leading to a slight decrease in the removal rate. The high-pressure washing group also caused minor damage, resulting in a slight weakening of separation performance. However, compared to strong alkaline cleaning agents, the cleaning agent of this invention significantly improves membrane material friendliness, greatly reducing damage at the composition level. Furthermore, it is evident that the gentle cleaning method employed in this invention maximizes the protection of the membrane material, almost completely restoring its original performance after cleaning, demonstrating extremely excellent cleaning results.

Claims

1. A method for using a cleaning agent for a plant extract treatment membrane, characterized in that, The cleaning agent comprises the following components in parts by weight: 30-60 parts of alkaline cleaning agent, 0.1-5 parts of surfactant, 1-20 parts of alkaline enzyme protein cleaning agent, and penetrant fatty alcohol polyoxyethylene ether and dispersant sodium polyacrylate; Alkaline cleaning agents include base metal salts of tripolyphosphate and / or alkali metal salts and / or alkali metal hydroxides of ethylenediaminetetraacetic acid; Usage instructions include: 1) Dissolve the components other than the alkaline enzyme protein cleaning agent in warm water at ≥35 ℃ to obtain a cleaning base solution with a concentration of 0.3~0.5 wt%, and adjust the pH value of the cleaning base solution to 11.5~12 with a buffer. 2) Add alkaline enzyme protein cleaning agent to the cleaning solution to obtain the cleaning agent. Heat the solution to 40-50℃ and let the cleaning agent flow sequentially through a first pressure zone (1.20-1.50 bar), a second pressure zone (0.95-1.05 bar), a third pressure zone (0.65-0.80 bar), and a fourth pressure zone (0.25-0.35 bar), which are separated by capillary plates. Place the plant extract-treated membrane in the first, second, and third pressure zones sequentially for 25-30 minutes. After cleaning, rinse with water until the pH of the washing solution is 6-7 to complete the cleaning of the plant extract-treated membrane.

2. The method of using the cleaning agent for the plant extract treatment membrane according to claim 1, characterized in that, The surfactant is sodium dodecyl sulfonate and / or dodecylphenol polyoxyethylene ether and / or sodium polystyrene sulfonate.

3. The method of using the cleaning agent for the plant extract treatment membrane according to claim 1, characterized in that, The alkaline enzyme protein cleaning agent includes an enzyme-containing agent and a stabilizer; The enzyme-containing agent includes α-chymotrypsin and / or N-acetylmuraminase and / or W146 subtilisin. The stabilizer is fatty alcohol polyvinyl ether and / or sodium borate; The mass ratio of the enzyme-containing agent to the stabilizer is 1:0.01 to 0.

1.

4. The method of using the cleaning agent for the plant extract treatment membrane according to claim 3, characterized in that, The stabilizer contains at least sodium borate.

5. The method of using the cleaning agent for the plant extract treatment membrane according to claim 1, characterized in that, The amount of the penetrant used is ≤10 parts by weight.

6. The method of using the cleaning agent for the plant extract treatment membrane according to claim 1, characterized in that, The amount of the dispersant is ≤10 parts by weight.

7. The method of using the cleaning agent for the plant extract treatment membrane according to claim 1, characterized in that, In step 2), the cleaning time for the plant extract treatment membrane in the first pressure zone, the second pressure zone, and the third pressure zone is 25 min.

8. The method of using the cleaning agent for the plant extract treatment membrane according to claim 1, characterized in that, The control pressure in the first pressure zone is 1.35 bar; The control pressure in the second pressure zone is 1.00 bar; The control pressure in the third pressure zone is 0.70 bar; The control pressure in the fourth pressure zone is 0.30 bar.

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