Diaphragm bag immersion cleaning agent as well as preparation method and application thereof

Abstract

The invention discloses a diaphragm bag immersion cleaning agent and a preparation method and application thereof, and the diaphragm bag immersion cleaning agent comprises the following raw materials by weight: 8-11 parts of oxalic acid, 10-15 parts of hydrogen peroxide, 10-15 parts of a composite surfactant, 5-8 parts of a chelating agent, 4-6 parts of ethylene glycol monomethyl ether, 1-3 parts of sodium hexametaphosphate, and 100-120 parts of deionized water. According to the diaphragm bag immersion cleaning agent provided by the invention, various assistants are compounded in a specific proportion, and manganese dioxide and organic matter dirt on a diaphragm bag are effectively removed by utilizing the acidity of oxalic acid and the oxidability of hydrogen peroxide for synergistic interaction; the composite surfactant can reduce the surface tension of the system and improve the cleaning efficiency; through interaction of all the raw materials, the adhesive force between dirt and the surface of the diaphragm bag is reduced, the dirt can be separated from the surface of the diaphragm bag more easily, and the cleaning efficiency of the diaphragm bag is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of soaking agents, and in particular relates to a membrane bag soaking agent and a preparation method and application thereof. Background Art

[0002] Electrolytic manganese diaphragm bags are mainly used in the production process of electrolytic manganese to wrap the anode and separate it from the cathode product. Its main function is to prevent the metal manganese precipitated from the cathode from being deposited on the anode, affecting the current efficiency and product quality. At the same time, it also allows ions to migrate between the cathode and the cathode to maintain the electrolysis process. However, as the diaphragm bag is used for a longer time, manganese hydroxide will gradually deposit on the cathode surface to form a filter cake during the electrolysis process. If it is not cleaned in time, the filter cake resistance of the diaphragm bag may be too high, affecting the circulation of the electrolyte, reducing the current efficiency, and even causing production interruption; and during the production process, the calcium ion concentration in the electrolyte will gradually increase, forming calcium sulfate precipitation, and other heavy metal ions in the electrolyte may also be deposited on the diaphragm bag, resulting in pore blockage and increased filter cake resistance.

[0003] At present, the cleaning of diaphragm bags mainly adopts a combination of simple water washing and chemical agent soaking. Before soaking, it is usually preliminarily rinsed with a high-pressure water gun, and then the diaphragm bag is transferred to the cleaning tank, and then soaked in a solution containing a certain concentration of chemical cleaning agent. The soaking time depends on the severity of the dirt, generally ranging from several hours to one day. For diaphragm bags with poor soaking effect, manual kneading is adopted, the diaphragm bag is removed from the diaphragm frame and mechanically stirred and washed, and the diaphragm bag is discarded and replaced with a new one. These methods greatly increase production costs.

[0004] Using traditional cleaning methods, it is difficult to completely remove some stubborn anode mud and other mixed dirt, such as ammonium sulfate, manganese dioxide, and calcium sulfate mixtures, which have accumulated in the micropores of the diaphragm bag for a long time. These residual dirt will affect the permeability of the diaphragm bag, thereby reducing the electrolysis efficiency. Due to uneven cleaning, different parts of the diaphragm bag may have different cleaning degrees, resulting in local performance degradation and affecting the stability of the entire electrolysis process.

[0005] Although high-pressure water gun flushing and mechanical stirring help to clean dirt, they can also easily cause physical damage to the diaphragm bag. For example, the impact of the high-pressure water gun may deform or break the microporous structure of the diaphragm bag, and the friction during mechanical stirring may also cause the surface of the diaphragm bag to wear, thereby shortening the service life of the diaphragm bag. After multiple cleanings, the breakage rate of the diaphragm bag increased significantly, and the service life was shortened by about 20-30% compared with the diaphragm bag that had not been cleaned.

[0006] Therefore, it is of great significance to develop a diaphragm bag cleaning agent in the art to improve the dirt removal rate and extend the service life of the diaphragm bag when cleaning the diaphragm bag of the electrolytic workshop. Summary of the invention

[0007] In view of the deficiencies in the prior art, the object of the present invention is to provide a diaphragm bag cleaning agent and a preparation method and application thereof.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A membrane bag soaking agent, comprising the following raw materials in parts by weight:

[0010] 8-11 parts of oxalic acid, 10-15 parts of hydrogen peroxide, 10-15 parts of complex surfactant, 5-8 parts of chelating agent, 4-6 parts of ethylene glycol monomethyl ether, 1-3 parts of sodium hexametaphosphate, and 100-120 parts of deionized water.

[0011] In the present invention, various additives are compounded in a specific ratio, the acidity of oxalic acid and the oxidizing property of hydrogen peroxide are utilized to synergistically enhance the effect, and manganese dioxide and organic dirt on the diaphragm bag are effectively removed; ethylene glycol monomethyl ether is used as a penetrant to further improve the penetration ability of the cleaning liquid into the micropores of the diaphragm bag; sodium hexametaphosphate is used as a dispersant to effectively disperse the dirt particles and prevent the dirt particles from being re-deposited on the surface of the diaphragm bag, thereby improving the cleaning effect and preventing secondary pollution; through the interaction of the various raw materials, the adhesion between the dirt and the surface of the diaphragm bag is reduced, so that the dirt can be more easily separated from the surface of the diaphragm bag.

[0012] Preferably, a diaphragm bag soaking agent comprises the following raw materials, measured by weight: 9-10 parts of oxalic acid, 10-13 parts of hydrogen peroxide, 12-15 parts of complex surfactant, 6-7 parts of chelating agent, 4-5 parts of ethylene glycol monomethyl ether, 1-2 parts of sodium hexametaphosphate, and 100-110 parts of deionized water.

[0013] Preferably, the mass concentration of the hydrogen peroxide is 20-30%, and the chelating agent is one or both of disodium EDTA and tetrasodium EDTA.

[0014] Preferably, the preparation method of the composite surfactant comprises the following steps:

[0015] S1, fatty alcohol polyoxyethylene ether is added to ethyl acetate, then 4-(chloromethyl)phenylacetic acid is added, and constant temperature reaction is carried out under nitrogen atmosphere, and pH is controlled at 8-9 during the reaction process. After the reaction is completed, it is cooled to room temperature, and ethyl acetate is removed by rotary evaporation to obtain modified fatty alcohol polyoxyethylene ether;

[0016] S2, adding the modified fatty alcohol polyoxyethylene ether in step S1 into deionized water, heating and stirring, then adding alkyl polysaccharide, stirring evenly, adding polyether-modified heptamethyltrisiloxane and butanediol, and performing ultrasonic treatment to obtain a composite surfactant.

[0017] Preferably, the fatty alcohol polyoxyethylene ether in step S1 is one or both of AEO-7 and AEO-9; the mass ratio of the fatty alcohol polyoxyethylene ether, ethyl acetate and 4-(chloromethyl)phenylacetic acid is 40-50:600-800:15-20, and the temperature of the isothermal reaction is 70-80°C and the time is 7-10h.

[0018] Preferably, the mass ratio of the modified fatty alcohol polyoxyethylene ether, deionized water, alkyl polysaccharide, polyether-modified heptamethyltrisiloxane, and butanediol in step S2 is 20-30:100-120:15-20:8-12:5-10.

[0019] In the present invention, the composite surfactant is prepared by using fatty alcohol polyoxyethylene ether as raw material, reacting it with 4-(chloromethyl)phenylacetic acid, introducing 4-(chloromethyl)phenylacetic acid into the end of fatty alcohol polyoxyethylene ether, changing the molecular arrangement of fatty alcohol polyoxyethylene ether, thereby reducing the foaming property of fatty alcohol polyoxyethylene ether, and then compounding with alkyl polyglycoside, polyether-modified heptamethyl trisiloxane and butanediol. The alkyl polyglycoside has good wetting, emulsifying, dispersing and solubilizing abilities, has good removal effects on various dirts, and synergistically improves the washing ability of the soaking agent with the modified fatty alcohol polyoxyethylene ether. At the same time, the added polyether-modified heptamethyl trisiloxane can improve the wettability and spreadability of the soaking agent, so that the soaking agent has higher washing efficiency; the added butanediol can assist other raw materials to better penetrate into the diaphragm, thereby improving the cleaning effect.

[0020] Preferably, the temperature of the heating and stirring in step S2 is 50-60° C., and the time is 30-50 min; the frequency of the ultrasonic treatment is 5-8 kHz, and the time is 20-30 min.

[0021] The present invention also protects a method for preparing the membrane bag cleaning agent as described above, comprising the following steps:

[0022] Weigh the raw materials according to the formula, mix water, ethylene glycol monomethyl ether and oxalic acid evenly, then add composite surfactant, hydrogen peroxide, chelating agent and sodium hexametaphosphate in sequence, and stir at a speed of 80-120r / min for 30-50min to obtain the product.

[0023] The present invention also protects a method for cleaning the diaphragm bags of an electrolytic plant using the diaphragm bag cleaning agent as described above, comprising the following steps:

[0024] Put the contaminated diaphragm bag into a bucket of clean water for aeration and soaking. After soaking, put it into a soaking bucket containing a cleaning agent for aeration and soaking. After soaking, put it into a clean water tank for rinsing. After rinsing, dry it.

[0025] Preferably, the aeration soaking time is 20-30 minutes; the mass concentration of the soaking agent in the soaking tank is 10%, the aeration soaking temperature is 30-35°C, the time is 30-40 minutes; the rinsing time is 10-20 minutes; the aeration intensity is 15-20m 3 / (m 2 *h).

[0026] In the present invention, the diaphragm bag is cleaned by combining a specific cleaning agent with aeration, which can ensure that the cleaning agent solution is in full contact with the dirt on the surface of the diaphragm bag without directly causing physical damage to the diaphragm bag. This method accelerates the peeling and dissolution process of dirt from the surface of the diaphragm bag and improves the cleaning efficiency.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The diaphragm bag cleaning agent provided by the present invention is prepared by compounding various auxiliary agents in a specific ratio, utilizing the acidity of oxalic acid and the oxidizing property of hydrogen peroxide to synergistically enhance the effect, and effectively remove manganese dioxide and organic dirt on the diaphragm bag; the composite surfactant can reduce the surface tension of the system and improve the cleaning efficiency; the chelating agent can chelate the metal calcium ions in the cleaning solution and remove the calcium salt in the dirt; ethylene glycol monomethyl ether is used as a penetrant to further improve the penetration ability of the cleaning solution into the micropores of the diaphragm bag; sodium hexametaphosphate is used as a dispersant to effectively disperse the dirt particles and prevent the dirt particles from redepositing on the surface of the diaphragm bag, thereby improving the cleaning effect and preventing secondary pollution; through the interaction of the various raw materials, the adhesion between the dirt and the surface of the diaphragm bag is reduced, so that the dirt is more easily detached from the surface of the diaphragm bag, thereby improving the cleaning efficiency of the diaphragm bag.

[0029] (2) The membrane bag cleaning agent provided by the present invention comprises a composite surfactant added thereto, wherein the composite surfactant is prepared by reacting fatty alcohol polyoxyethylene ether with 4-(chloromethyl)phenylacetic acid to end-cap the fatty alcohol polyoxyethylene ether with 4-(chloromethyl)phenylacetic acid, thereby changing the molecular arrangement of the fatty alcohol polyoxyethylene ether and reducing the foaming property of the fatty alcohol polyoxyethylene ether, and then compounding the composite surfactant with an alkyl polyglycoside, a polyether-modified heptamethyl trisiloxane and butanediol, wherein the alkyl polyglycoside has good wetting, emulsifying, dispersing and solubilizing abilities. It has a good removal effect on various dirts, and synergizes with modified fatty alcohol polyoxyethylene ether to improve the washing ability of the soaking agent. At the same time, the added polyether modified heptamethyltrisiloxane can improve the wettability and spreadability of the soaking agent; the added butanediol can assist other raw materials to better penetrate into the diaphragm and improve the cleaning effect; the composite surfactant not only enhances the penetration ability of the soaking liquid into the micropores of the diaphragm bag, improves the cleaning efficiency, but also effectively controls the generation of foam during the aeration soaking process, avoiding the cleaning inconvenience caused by a large amount of foam.

[0030] (3) The diaphragm bag cleaning agent provided by the present invention can ensure that the cleaning agent solution is in full contact with the dirt on the surface of the diaphragm bag without directly causing physical damage to the diaphragm bag by cooperating with aeration to clean the diaphragm bag. This method accelerates the peeling and dissolution of dirt from the surface of the diaphragm bag, thereby improving the cleaning efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a real picture of the diaphragm bag that has not been cleaned after being used for 60 days in the present invention;

[0032] Figure 2 This is a physical picture of the diaphragm bag after cleaning in Example 1. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the present invention, the fatty alcohol polyoxyethylene ether AEO-9 was purchased from Dezhou Hongchen Chemical Co., Ltd., with an HLB value of 12.5; the alkyl polysaccharide was purchased from Guangzhou Qixu Chemical Co., Ltd., with a model of APG-0810; and the polyether-modified heptamethyl trisiloxane was purchased from Qingdao Baisenmao New Materials Co., Ltd., with a model of BM-409.

[0035] Example 1

[0036] A membrane bag soaking agent, comprising the following raw materials in parts by weight:

[0037] 10 parts of oxalic acid, 13 parts of 25% hydrogen peroxide by mass, 13 parts of composite surfactant, 7 parts of disodium EDTA, 5 parts of ethylene glycol monomethyl ether, 2 parts of sodium hexametaphosphate, and 110 parts of deionized water.

[0038] The preparation method of the composite surfactant comprises the following steps:

[0039] S1, add 45g fatty alcohol polyoxyethylene ether AEO-9 to 700g ethyl acetate, then add 17g 4-(chloromethyl)phenylacetic acid, and react at a constant temperature of 75°C under a nitrogen atmosphere for 9h. During the reaction, triethylamine is added every 1h to control the pH at 8.5. After the reaction is completed, cool to room temperature, and remove ethyl acetate by rotary evaporation to obtain modified fatty alcohol polyoxyethylene ether;

[0040] S2. Add 25 g of modified fatty alcohol polyoxyethylene ether AEO-9 in step S1 to 110 g of deionized water, heat and stir at 55 ° C for 40 min, then add 18 g of alkyl polysaccharide, stir evenly, add 10 g of polyether-modified heptamethyltrisiloxane and 8 g of 1,4-butanediol, and perform ultrasonic treatment at a frequency of 6 kHz for 25 min to obtain a composite surfactant.

[0041] A method for preparing a membrane bag cleaning agent comprises the following steps:

[0042] Weigh the raw materials according to the above formula, mix water, ethylene glycol monomethyl ether and oxalic acid evenly, then add composite surfactant, hydrogen peroxide, disodium EDTA and sodium hexametaphosphate in sequence, and stir at a speed of 100 r / min for 40 minutes to obtain the product.

[0043] Example 2

[0044] A membrane bag soaking agent, comprising the following raw materials in parts by weight:

[0045] 8 parts of oxalic acid, 15 parts of 20% hydrogen peroxide by mass, 10 parts of composite surfactant, 5 parts of tetrasodium EDTA, 4 parts of ethylene glycol monomethyl ether, 1 part of sodium hexametaphosphate, and 100 parts of deionized water.

[0046] The preparation method of the composite surfactant comprises the following steps:

[0047] S1, add 40g fatty alcohol polyoxyethylene ether AEO-9 to 600g ethyl acetate, then add 15g 4-(chloromethyl)phenylacetic acid, and react at a constant temperature of 70°C in a nitrogen atmosphere for 10h. During the reaction, triethylamine is added every 1h to control the pH at 8. After the reaction is completed, cool to room temperature, and remove ethyl acetate by rotary evaporation to obtain modified fatty alcohol polyoxyethylene ether;

[0048] S2. Add 20 g of modified fatty alcohol polyoxyethylene ether AEO-9 in step S1 to 100 g of deionized water, heat and stir at 50 ° C for 50 min, then add 15 g of alkyl polysaccharide, stir evenly, add 8 g of polyether-modified heptamethyl trisiloxane and 5 g of 1,4-butanediol, and perform ultrasonic treatment at a frequency of kHz for 30 min to obtain a composite surfactant.

[0049] A method for preparing a membrane bag cleaning agent comprises the following steps:

[0050] Weigh the raw materials according to the above formula, mix water, ethylene glycol monomethyl ether and oxalic acid evenly, then add composite surfactant, hydrogen peroxide, tetrasodium EDTA and sodium hexametaphosphate in sequence, and stir at a speed of 80r / min for 50min to obtain the product.

[0051] Example 3

[0052] A membrane bag cleaning agent, comprising the following raw materials in parts by weight:

[0053] 11 parts of oxalic acid, 10 parts of 30% hydrogen peroxide by mass, 15 parts of composite surfactant, 8 parts of disodium EDTA, 6 parts of ethylene glycol monomethyl ether, 3 parts of sodium hexametaphosphate, and 120 parts of deionized water.

[0054] The preparation method of the composite surfactant comprises the following steps:

[0055] S1, add 50g fatty alcohol polyoxyethylene ether AEO-9 to 800g ethyl acetate, then add 20g 4-(chloromethyl)phenylacetic acid, and react at a constant temperature of 80°C in a nitrogen atmosphere for 7h. During the reaction, triethylamine is added every 1h to control the pH at 9. After the reaction is completed, cool to room temperature, and remove ethyl acetate by rotary evaporation to obtain modified fatty alcohol polyoxyethylene ether;

[0056] S2. Add 30 g of modified fatty alcohol polyoxyethylene ether AEO-9 in step S1 to 120 g of deionized water, heat and stir at 60° C. for 30 min, then add 20 g of alkyl polysaccharide, stir evenly, add 12 g of polyether-modified heptamethyltrisiloxane and 10 g of 1,4-butanediol, and perform ultrasonic treatment at a frequency of 5 kHz for 20 min to obtain a composite surfactant.

[0057] A method for preparing a membrane bag cleaning agent comprises the following steps:

[0058] Weigh the raw materials according to the above formula, mix water, ethylene glycol monomethyl ether and oxalic acid evenly, then add composite surfactant, hydrogen peroxide, disodium EDTA and sodium hexametaphosphate in sequence, and stir at a speed of 120r / min for 30min to obtain the product.

[0059] Comparative Example 1

[0060] A membrane bag cleaning agent, comprising the following raw materials in parts by weight:

[0061] 10 parts of oxalic acid, 13 parts of 25% hydrogen peroxide by mass, 13 parts of composite surfactant, 7 parts of disodium EDTA, 5 parts of ethylene glycol monomethyl ether, 2 parts of sodium hexametaphosphate, and 110 parts of deionized water.

[0062] The preparation method of the composite surfactant comprises the following steps:

[0063] Add 25g of fatty alcohol polyoxyethylene ether AEO-9 to 110g of deionized water, heat and stir at 55°C for 40min, then add 18g of alkyl polysaccharide, stir evenly, add 10g of polyether modified heptamethyltrisiloxane and 8g of 1,4-butanediol, and perform ultrasonic treatment at a frequency of 6kHz for 25min to obtain a composite surfactant.

[0064] A method for preparing a membrane bag cleaning agent comprises the following steps:

[0065] Weigh the raw materials according to the above formula, mix water, ethylene glycol monomethyl ether and oxalic acid evenly, then add composite surfactant, hydrogen peroxide, disodium EDTA and sodium hexametaphosphate in sequence, and stir at a speed of 100 r / min for 40 minutes to obtain the product.

[0066] Compared with Example 1, the fatty alcohol polyoxyethylene ether was not modified in this comparative example.

[0067] Comparative Example 2

[0068] A membrane bag cleaning agent, comprising the following raw materials in parts by weight:

[0069] 10 parts of oxalic acid, 13 parts of 25% hydrogen peroxide by mass, 13 parts of composite surfactant, 7 parts of disodium EDTA, 5 parts of ethylene glycol monomethyl ether, 2 parts of sodium hexametaphosphate, and 110 parts of deionized water.

[0070] The preparation method of the composite surfactant comprises the following steps:

[0071] S1, add 45g fatty alcohol polyoxyethylene ether AEO-9 to 700g ethyl acetate, then add 17g 4-(chloromethyl)phenylacetic acid, and react at a constant temperature of 75°C under a nitrogen atmosphere for 9h. During the reaction, triethylamine is added every 1h to control the pH at 8.5. After the reaction is completed, cool to room temperature, and remove ethyl acetate by rotary evaporation to obtain modified fatty alcohol polyoxyethylene ether;

[0072] S2. Add 43 g of modified fatty alcohol polyoxyethylene ether AEO-9 in step S1 to 110 g of deionized water, heat and stir at 55° C. for 40 min, then add 10 g of polyether-modified heptamethyltrisiloxane and 8 g of 1,4-butanediol, and perform ultrasonic treatment at a frequency of 6 kHz for 25 min to obtain a composite surfactant.

[0073] A method for preparing a membrane bag cleaning agent comprises the following steps:

[0074] Weigh the raw materials according to the above formula, mix water, ethylene glycol monomethyl ether and oxalic acid evenly, then add composite surfactant, hydrogen peroxide, disodium EDTA and sodium hexametaphosphate in sequence, and stir at a speed of 100 r / min for 40 minutes to obtain the product.

[0075] Compared with Example 1, this comparative example does not add alkyl polyglycoside to the composite surfactant.

[0076] Comparative Example 3

[0077] A membrane bag soaking agent, comprising the following raw materials in parts by weight:

[0078] 10 parts of oxalic acid, 13 parts of 25% hydrogen peroxide by mass, 13 parts of composite surfactant, 7 parts of disodium EDTA, 5 parts of ethylene glycol monomethyl ether, 2 parts of sodium hexametaphosphate, and 110 parts of deionized water.

[0079] The preparation method of the composite surfactant comprises the following steps:

[0080] 43 g of alkyl polyglycoside was added to 110 g of deionized water, heated and stirred at 55° C. for 40 min, and then 10 g of polyether-modified heptamethyltrisiloxane and 8 g of 1,4-butanediol were added, and ultrasonic treatment was performed at a frequency of 6 kHz for 25 min to obtain a composite surfactant.

[0081] A method for preparing a membrane bag cleaning agent comprises the following steps:

[0082] Weigh the raw materials according to the above formula, mix water, ethylene glycol monomethyl ether and oxalic acid evenly, then add composite surfactant, hydrogen peroxide, disodium EDTA and sodium hexametaphosphate in sequence, and stir at a speed of 100 r / min for 40 minutes to obtain the product.

[0083] Compared with Example 1, this comparative example does not add modified fatty alcohol polyoxyethylene ether to the composite surfactant.

[0084] The membrane bag cleaning agent prepared in Example 1-3 and Comparative Example 1-3 was used to clean the membrane bags in the electrolysis workshop. The specific method was as follows: a 60-day-old membrane bag was selected, and the contaminated membrane bag was placed in a clean water bucket for aeration and soaking for 25 minutes. A Roots blower was used for physical aeration, and the aeration intensity was 16m / s. 3 / (m 2 *h), after the soaking is completed, add the soaking tank containing the soaking agent (mass concentration is 10%) for aeration and soaking, and use the Roots blower for physical aeration, and the aeration intensity is 16m 3 / (m 2 *h), the aeration immersion temperature is 30℃, the time is 40min, after the immersion is completed, add it to the clean water tank and rinse for 15min, after rinsing, dry it.

[0085] The initial permeability of the membrane bag is 1.29L / m 2 *min, the permeability and damage rate of the diaphragm bag were tested before and after cleaning, and the results are shown in Table 1:

[0086] Table 1

[0087] <![CDATA[Permeability before cleaning (m 2 *min)]]> <![CDATA[Permeability after cleaning (m 2 *min)]]> Breakage rate High pressure water gun + clean water 0.34 0.52 26.3％ Example 1 0.35 1.15 3.9％ Example 2 0.36 1.04 4.3％ Example 3 0.35 1.11 4.2％ Comparative Example 1 0.37 0.89 4.6％ Comparative Example 2 0.35 0.76 4.1％ Comparative Example 3 0.36 0.70 4.4％

[0088] It can be seen from Table 1 above that the diaphragm bag cleaning agent prepared by the present invention has good decontamination effect. The permeability of the diaphragm bag after cleaning is 89% of that of a new diaphragm bag, and the physical damage to the diaphragm bag is significantly reduced, with a breakage rate of only about 4%. The service life of the diaphragm bag can be extended, and it has good application prospects.

[0089] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A membrane bag cleaning agent, characterized in that: By weight, it includes the following raw materials: 8-11 parts of oxalic acid, 10-15 parts of hydrogen peroxide, 10-15 parts of complex surfactant, 5-8 parts of chelating agent, 4-6 parts of ethylene glycol monomethyl ether, 1-3 parts of sodium hexametaphosphate, and 100-120 parts of deionized water.

2. The diaphragm bag cleaning agent according to claim 1, characterized in that: The raw materials are as follows, measured by weight: 9-10 parts of oxalic acid, 10-13 parts of hydrogen peroxide, 12-15 parts of composite surfactant, 6-7 parts of chelating agent, 4-5 parts of ethylene glycol monomethyl ether, 1-2 parts of sodium hexametaphosphate and 100-110 parts of deionized water.

3. The membrane bag cleaning agent according to claim 1, characterized in that: The mass concentration of the hydrogen peroxide is 20-30%, and the chelating agent is one or both of disodium EDTA and tetrasodium EDTA.

4. The membrane bag cleaning agent according to claim 1, characterized in that: The preparation method of the composite surfactant comprises the following steps: S1, fatty alcohol polyoxyethylene ether is added to ethyl acetate, then 4-(chloromethyl)phenylacetic acid is added, and constant temperature reaction is carried out under nitrogen atmosphere, and pH is controlled at 8-9 during the reaction process. After the reaction is completed, it is cooled to room temperature, and ethyl acetate is removed by rotary evaporation to obtain modified fatty alcohol polyoxyethylene ether; S2, adding the modified fatty alcohol polyoxyethylene ether in step S1 into deionized water, heating and stirring, then adding alkyl polysaccharide, stirring evenly, adding polyether-modified heptamethyltrisiloxane and butanediol, and performing ultrasonic treatment to obtain a composite surfactant.

5. The membrane bag cleaning agent according to claim 1, characterized in that: In step S1, the fatty alcohol polyoxyethylene ether is one or two of AEO-7 and AEO-9; the mass ratio of the fatty alcohol polyoxyethylene ether, ethyl acetate and 4-(chloromethyl)phenylacetic acid is 40-50:600-800:15-20, and the temperature of the isothermal reaction is 70-80°C and the time is 7-10h.

6. The membrane bag cleaning agent according to claim 1, characterized in that: The mass ratio of the modified fatty alcohol polyoxyethylene ether, deionized water, alkyl polysaccharide, polyether-modified heptamethyl trisiloxane and butanediol in step S2 is 20-30:100-120:15-20:8-12:5-10.

7. The membrane bag cleaning agent according to claim 1, characterized in that: The temperature of the heating and stirring in step S2 is 50-60° C., and the time is 30-50 min; the frequency of the ultrasonic treatment is 5-8 kHz, and the time is 20-30 min.

8. A method for preparing the membrane bag cleaning agent according to any one of claims 1 to 7, characterized in that: The following steps are involved: Weigh the raw materials according to the formula, mix water, ethylene glycol monomethyl ether and oxalic acid evenly, then add composite surfactant, hydrogen peroxide, chelating agent and sodium hexametaphosphate in sequence, and stir at a speed of 80-120r / min for 30-50min to obtain the product.

9. A method for cleaning the diaphragm bag of an electrolytic plant using the diaphragm bag cleaning agent according to any one of claims 1 to 7, characterized in that: The following steps are involved: Put the contaminated diaphragm bag into a bucket of clean water for aeration and soaking. After soaking, put it into a soaking bucket containing a cleaning agent for aeration and soaking. After soaking, put it into a clean water tank for rinsing. After rinsing, dry it.

10. The method according to claim 9, characterized in that The aeration soaking time is 20-30 minutes; the mass concentration of the soaking agent in the soaking tank is 10%, the aeration soaking temperature is 30-35°C, and the time is 30-40 minutes; the rinsing time is 10-20 minutes; the aeration intensity is 15-20m 3 / (m 2 *h).

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