阅读说明：本技术 一种陶瓷膜清洗剂及其制备、清洗方法 (Ceramic membrane cleaning agent and preparation and cleaning methods thereof ) 是由 褚运伟 孙辉 胡文军 陶贵立 张宇 王坤鹏 陈奇 张柏鸿 于 2021-09-18 设计创作，主要内容包括：一种陶瓷膜清洗剂,该清洗剂由氧化性气体和液体强化剂共同组成,其中氧化性气体为臭氧,液体强化剂为碱性强化剂A或酸性强化剂B。本发明特别针对陶瓷膜系统在线和运行间歇清洗设计,本发明清洗剂绿色环保,不污染环境,而且对有机物,特别是沉积的顽垢有很好的清洗效果。(The ceramic membrane cleaning agent consists of oxidizing gas and liquid reinforcer, wherein the oxidizing gas is ozone, and the liquid reinforcer is alkali reinforcer A or acid reinforcer B. The cleaning agent is especially designed for the on-line and operation intermittent cleaning of the ceramic membrane system, is green and environment-friendly, does not pollute the environment, and has good cleaning effect on organic matters, especially deposited stubborn dirt.)

1. The ceramic membrane cleaning agent is characterized by comprising oxidizing gas and a liquid enhancer, wherein the oxidizing gas is ozone, and the liquid enhancer is an alkaline enhancer A; the alkaline enhancer A comprises the following components in percentage by weight: 5-18 parts of sodium hydroxide, 12-36 parts of hydrogen peroxide, 10-30 parts of ethanol, 3-13 parts of polyaspartic acid sodium and 30-45 parts of demineralized water.

2. A ceramic membrane cleaning agent according to claim 1, wherein the flow rate of ozone in the oxidizing gas component in the cleaning agent is 1.0-2.0L/min.

3. The ceramic membrane cleaning agent is characterized by comprising oxidizing gas and a liquid enhancer, wherein the oxidizing gas is ozone, and the liquid enhancer is an acid enhancer B; the acid enhancer B comprises the following components in percentage by weight: 8-18 parts of formic acid, 10-25 parts of glycolic acid, 10-30 parts of salicylic acid, 12-32 parts of ethanol and 25-40 parts of demineralized water.

4. A ceramic membrane cleaner as claimed in claim 3, wherein the flow rate of the oxidising gas component ozone in the cleaner is: 0.5 to 1.0L/min.

5. A method for preparing the alkaline enhancer a, wherein the alkaline enhancer a is used for preparing the ceramic membrane cleaning agent according to claim 1 or 2, and the method comprises the following steps:

1) preparing sodium hydroxide solution from sodium hydroxide and demineralized water, and diluting the sodium hydroxide solution by using ethanol;

2) adding hydrogen peroxide into the reactor and cooling to be not higher than 0 ℃;

3) and (2) slowly adding the mixed solution of the sodium polyaspartate and the diluted sodium hydroxide into the reactor in sequence under stirring, maintaining the reaction temperature at 0-5 ℃, and uniformly mixing the solution in the whole reaction process under vacuum.

6. A method for preparing the acid enhancer B, which is used for preparing the ceramic membrane cleaning agent as claimed in claim 3 or 4, and comprises the following steps: at normal temperature, the desalted water, the ethanol, the formic acid, the salicylic acid and the glycollic acid are stirred and mixed evenly.

7. A method for cleaning a ceramic membrane according to claim 1 or 2, comprising the steps of:

1) preparing a 1% solution of an alkaline enhancer A by mass, and heating to 35-45 ℃;

2) cleaning for 3-6 min in a non-permeation circulation manner;

3) cleaning for 2-4 min in a permeation circulation mode, stopping cleaning, inputting ozone for 10-15 min, and controlling the ozone pressure: 0.06-0.12 Mpa; repeating the steps for 1-3 times, emptying, and rinsing with water until the drained water is neutral;

4) ozone input mode: reversely inputting ozone into the system from a water production end of the ceramic membrane system; or ozone is alternately input into the system from the water production end and the cleaning water inlet end.

8. A method for cleaning a ceramic membrane according to claim 3 or 4, comprising the steps of:

1) preparing an acid enhancer B into a solution with the mass concentration of 1%, and heating to 25-35 ℃;

2) cleaning for 3-6 min in a non-permeation circulation manner;

3) cleaning for 2-4 min in a permeation circulation mode, and stopping cleaning; inputting ozone for 10-15 min, wherein the ozone pressure is as follows: not more than 0.5 Mpa; repeating the steps for 1-2 times, emptying, rinsing with water until the drained water is neutral, and finishing the cleaning process;

4) ozone input mode: reversely inputting ozone into the system from a water production end of the ceramic membrane system; or ozone is alternately input into the system from the water production end and the cleaning water inlet end.

Technical Field

The invention relates to the technical field of water treatment, in particular to a ceramic membrane cleaning agent and preparation and cleaning methods thereof.

Background

After the ceramic membrane in the ceramic membrane system is operated for a period of time, certain components in the feed liquid, such as oil, colloid and other pollutants are adsorbed and deposited on the membrane surface, so that the osmotic resistance of the membrane is greatly increased, and membrane surface pollution is formed. With the wide application of ceramic membranes in various fields, particularly in the fields of reclaimed water reuse treatment, industrial oily wastewater treatment, oilfield produced water treatment and the like, a fouling layer and a gel layer are easily formed on the membrane surface due to the complex and variable feed liquid components and high oil content. The fouling layer is an adsorption layer formed by adsorbing colloid substances, microorganisms, metabolites and the like on the membrane surface, becomes dense under the action of osmotic pressure along with the operation of equipment, and the membrane surfaces are overlapped together to form a double membrane structure. The gel layer is a three-layer composite structure with strong resistance, wherein the concentration of emulsified oil near the membrane surface is continuously increased and gradually reaches the gel concentration. With the prolonging of the operation time, the formed compact mixed pollutants are not only attached to the membrane surface, but also permeate into the membrane pores, and even block the membrane pores. The simultaneous presence of such membrane surface and pore fouling makes the cleaning of ceramic membranes for these applications more difficult.

The cleaning method for ceramic membrane pollution generally comprises physical cleaning and chemical cleaning. The physical cleaning mainly comprises a hydraulic flushing method, a back flushing method, an ultrasonic cleaning method, a mechanical cleaning method and the like. When the pollution is serious, the problem of membrane pollution cannot be solved by a pure physical method, and a chemical cleaning agent is required to be used for cleaning. The following ceramic membrane cleaning agents are generally used in the prior art:

acid solutions such as nitric acid, phosphoric acid, citric acid and the like;

② alkali liquor, such as sodium hydroxide, sodium carbonate, etc.;

③ oxidizing agents, such as sodium hypochlorite, isothiazolinone, etc.;

chelating agents such as EDTA and the like;

surfactant such as sodium dodecyl benzene sulfonate and ammonium alkyl benzene sulfonate;

sixthly, builder, such as sodium silicate, sodium hexametaphosphate, sodium tripolyphosphate, sodium metaborate and the like;

and corrosion inhibitors such as benzotriazole, sodium nitrate, alkylpyridinium chloride and the like.

The cleaning agents can be used alone or in combination.

According to search results, in the existing research on the ceramic membrane treatment of the oilfield produced water, Yuanjie and the like (Yuanjie, Libivin, Yanan and the like) and the research on membrane pollution cleaning when the ceramic membrane treats the oilfield produced water, petroleum machinery 2003,31(7):1-5) alternately cleans a composite medicament mainly comprising a surfactant, a chelating agent and alkali and strong acid for the ceramic membrane treated by the oilfield produced water, and after reverse flushing, the final membrane flux recovery rate is about 60%. In the research, the majority of ceramic membrane cleaning agents can only clean ceramic membranes of certain treatment media, the universality is not strong, single-purification chemical agent cleaning and air-water backwashing are not thorough in cleaning, membrane pores are difficult to penetrate deeply, the flux recovery rate of the ceramic membranes is not high, and the cleaning effect is not ideal.

The Chinese patent with the application number of 200910027181.6 and the granted publication number of CN101564650B discloses a ceramic membrane cleaning agent, which comprises the following components in parts by mass: 50-60 parts of sodium hydroxide, 20-30 parts of calcium hydroxide, 5-10 parts of sodium hypochlorite, 5-10 parts of sodium dodecyl benzene sulfonate, 1-5 parts of tetraborate, 1-10 parts of sodium silicate and 1-5 parts of methyl cellulose.

The application number 201810319099.X, which is patent document, discloses a ceramic membrane cleaning agent, comprising an organic cleaning agent, an inorganic cleaning agent and a catalytic solvent, wherein the organic cleaning agent accounts for 85% of the whole cleaning agent, the inorganic cleaning agent accounts for 9% of the whole cleaning agent, and the catalytic solvent accounts for 6% of the whole cleaning agent; the inorganic cleaning agent comprises an oxidation stabilizer and an additive, wherein the oxygen stabilizer comprises hydrogen peroxide, peroxyformic acid, peroxyacetic acid, peroxypropionic acid, ozone and MgSO (MgSO)₄、MgCl₂One or a mixture of more than two of the above in any proportion; the additive comprises ferrous sulfate, sodium sulfite, NaOH, KOH and Ca (OH)₂One or a mixture of more than two of the above in any proportion. Wherein the organic cleaning agent comprises 50-75 parts by mass of sodium hydroxide, 3-15 parts by mass of sodium polyphosphate, 5-15 parts by mass of sodium alkyl benzene sulfonate, 2-8 parts by mass of diatomite, 1-8 parts by mass of sodium silicate, 2-6 parts by mass of sodium sulfate, 1-12 parts by mass of sodium carbonate, 0.5-4 parts by mass of hydroxymethyl cellulose, 5-10 parts by mass of sodium hypochlorite and dodecyl benzene sulfonate5-10 parts of sodium acid, 1-5 parts of sodium tetraborate and 1-10 parts of sodium silicate.

The two cleaning agents comprise the following components: such as tetraborate, sodium silicate, sodium polyphosphate and sodium sulfate, can not be recycled in the subsequent process, easily cause pollution, are not beneficial to environmental protection, and also do not meet the requirement of green circular economy. The liquid cleaning agent using chemical agent as main agent has the problems of large using amount of chemical agent, difficult deep penetration into membrane holes and incomplete cleaning.

Disclosure of Invention

The invention aims to provide a ceramic membrane cleaning agent and preparation and cleaning methods thereof, and the cleaning agent is especially designed for cleaning a ceramic membrane system on line and intermittently in operation, is green and environment-friendly, does not pollute the environment, and has a good cleaning effect on organic matters, especially deposited stubborn dirt.

In order to achieve the purpose, the invention adopts the following technical scheme:

a ceramic membrane cleaner, the cleaner is made up of oxidizing gas and liquid reinforcer together, wherein the oxidizing gas is ozone, the liquid reinforcer is alkaline reinforcer A; the alkaline enhancer A comprises the following components in percentage by weight: 5-18 parts of sodium hydroxide, 12-36 parts of hydrogen peroxide, 10-30 parts of ethanol, 3-13 parts of polyaspartic acid sodium and 30-45 parts of demineralized water.

The flow rate of the ozone in the oxidizing gas component in the cleaning agent is 1.0-2.0L/min.

The cleaning agent consists of oxidizing gas and a liquid enhancer, wherein the oxidizing gas is ozone, and the liquid enhancer is an acid enhancer B; the acid enhancer B comprises the following components in percentage by weight: 8-18 parts of formic acid, 10-25 parts of glycolic acid, 10-30 parts of salicylic acid, 12-32 parts of ethanol and 25-40 parts of demineralized water.

The flow of the oxidizing gas component ozone in the cleaning agent is as follows: 0.5 to 1.0L/min.

A method for preparing a basic enhancer A comprises the following steps:

1) preparing sodium hydroxide solution from sodium hydroxide and demineralized water, and diluting the sodium hydroxide solution by using ethanol;

2) adding hydrogen peroxide into a reactor, and then cooling the hydrogen peroxide to be not higher than 0 ℃ by using a low-temperature cooler;

3) and (2) slowly adding the mixed solution of the sodium polyaspartate and the diluted sodium hydroxide into the reactor in sequence under stirring, maintaining the reaction temperature at 0-5 ℃, and uniformly mixing the solution in the whole reaction process under vacuum.

A method for preparing the acid enhancer B for ceramic membrane cleaning agent according to claim 3 or 4, comprising: sequentially adding desalted water, ethanol, formic acid, salicylic acid and glycolic acid into a reaction kettle at normal temperature, and uniformly stirring and mixing.

The raw materials are all industrial super-grade pure, wherein the content of the effective component of sodium hydroxide is 99 wt%, the concentration of hydrogen peroxide is 27.5 wt%, the concentration of ethanol is 95 wt%, the concentration of sodium polyaspartate is 40 wt%, the concentration of formic acid is 85 wt%, the content of the effective component of glycolic acid is 99 wt%, and the content of the effective component of salicylic acid is 99 wt%.

A cleaning method of a ceramic membrane cleaning agent comprises the following steps:

1) emptying the materials, pre-washing with clear water, and washing loose dirt on the surface of the membrane cavity;

2) preparing a 1% solution of an alkaline enhancer A in a cleaning tank, and heating to 35-45 ℃;

3) cleaning for 3-6 min in a non-permeation circulation manner;

4) cleaning for 2-4 min in a permeation circulation mode, stopping cleaning, inputting ozone for 10-15 min, and controlling the ozone pressure: 0.06-0.12 Mpa, flow: 1.0-2.0L/min; repeating the steps for 1-3 times, emptying, and rinsing with water until the drained water is neutral;

5) ozone input mode: connecting an ozone output port with a ceramic membrane system water production pipe, and reversely inputting ozone into the system from a water production end of the ceramic membrane system; or the ozone output port is respectively connected with the ceramic membrane system water production pipe and the cleaning water inlet pipe, and ozone is alternately input into the system from the water production end and the cleaning water inlet end.

A cleaning method of a ceramic membrane cleaning agent comprises the following steps:

1) emptying materials, pre-washing with clear water, and washing loose dirt on the surface of the membrane cavity;

2) preparing the acid enhancer B into a solution with the mass concentration of 1% in a cleaning tank, and heating to 25-35 ℃;

3) cleaning for 3-6 min in a non-permeation circulation manner;

4) cleaning for 2-4 min in a permeation circulation mode, and stopping cleaning; inputting ozone for 10-15 min, wherein the ozone pressure is as follows: not more than 0.5Mpa, flow: 0.5-1.0L/min; repeating the steps for 1-2 times, emptying, rinsing with water until the drained water is neutral, and finishing the cleaning process;

5) ozone input mode: connecting an ozone output port with a ceramic membrane system water production pipe, and reversely inputting ozone into the system from a water production end of the ceramic membrane system; or the ozone output port is respectively connected with the ceramic membrane system water production pipe and the cleaning water inlet pipe, and ozone is alternately input into the system from the water production end and the cleaning water inlet end.

Adding and connecting mode of an auxiliary agent enhancer: the output port of the intensifying agent is connected with the cleaning water inlet pipe of the ceramic membrane system.

The non-permeation circular cleaning means that a valve for returning produced water to a cleaning tank is closed, the ceramic membrane is not allowed to produce water, and only the membrane cavity is cleaned.

The permeation circulation cleaning refers to opening a valve of the produced water return cleaning tank, and at the moment, the cleaning solution permeates to the water production end of the ceramic membrane, so that the membrane cavity and the membrane hole can be cleaned simultaneously.

The ozone has the characteristics of strong oxidative decomposition property, sterilization property, easy decomposition property and no residue, the ozone oxidizes organic matters into water, carbon dioxide and other mineral salts, the residual ozone can be quickly converted into oxygen, secondary pollution is not generated, the reaction condition of the process is mild, and especially the organic matters which are difficult to degrade or have stable structures can be effectively removed. Not only reduces the usage amount of chemical cleaning agents, but also reduces the damage of the cleaning link to the surface of the material, and prolongs the service life of equipment.

The strong oxidative decomposition of ozone is manifested by direct oxidation and indirect oxidation. The direct oxidation is a process of directly reacting ozone with organic matters in water to generate simple organic matters such as carboxylic acid and the like or directly oxidizing the simple organic matters to generate carbon dioxide and water, the reaction has selectivity, and the reaction generally occurs in a reaction system with acidic solution. The indirect oxidation belongs to a chemical reaction system for controlling mass transfer, is a non-selective instant reaction, has high reaction speed, and enables ozone to generate a large amount of hydroxyl radicals under the action of some free radical excitants and promoters, wherein the hydroxyl radicals have stronger oxidation capacity. Such reactions typically occur in reaction systems where the solution is basic. More hydroxyl free radicals are excited, and the cleaning effect and the cleaning efficiency can be greatly improved.

The combination of the ozone and the alkaline enhancer A and the combination of the ozone and the acidic enhancer B are combined for better exciting the oxidation potential of the ozone, so that a more ideal cleaning effect can be obtained.

Ozone is input into the system in a reverse direction or a forward and reverse direction alternately, firstly, the full contact between the ozone and organic pollutants is realized, and the gas brushing effect which can not be generated by a single pure chemical agent in a membrane hole can be generated in the micro-structure membrane hole, so that the dirt is dissolved and dispersed more easily due to the mechanical scouring of the gas with strong oxidizing property, and the aims of shortening the cleaning time and improving the efficiency are fulfilled; secondly, the alumina is used as a solid catalyst in the catalytic ozonization, the main material component of the ceramic membrane is the alumina, the ozone is reversely added, the contact with the catalyst is more facilitated, and the catalytic activity of the ceramic membrane mainly expresses the catalytic decomposition of the ozone and promotes the generation of hydroxyl radicals, so that the organic decomposition efficiency is improved; thirdly, common ozone passes through membrane pores by utilizing the microporous structure of the existing ceramic membrane to form nano-scale bubbles in the membrane tube, the nano-scale bubbles with the diameter smaller than that of the membrane pores are slow in rising speed in water, long in retention time and high in dissolving efficiency, and have good adsorption effect and high-efficiency removal rate on suspended matters and oils, and can permeate into the deep layer of the membrane pores to efficiently remove compact dirt which is difficult to remove by common chemical drugs, so that the deep layer of the membrane is cleaned; fourthly, the nano-scale bubbles have large gas-liquid contact surface area, good diffusivity and long retention time in water, and ensure high contact area and contact probability of the bubbles with liquid cleaning agents and dirt. Not only promotes the rapid catalytic oxidation of ozone, but also increases the contact action between the liquid medicament and the dirt, loosens the dirt, emulsifies and disperses in the cleaning fluid. The physical air washing and the chemical agent washing are combined to generate strong synergistic effect, and finally, the purposes of comprehensively sterilizing and thoroughly washing the membrane holes and the membrane cavities are achieved.

Sodium hydroxide and hydrogen peroxide are used as radical activators in an ozone reaction system to provide a large amount of hydroxide ions, the radical activators have an excitation effect on the generation of hydroxyl radicals, and under the action of the activators, a large amount of hydroxyl radicals can be generated in the ozone system, so that the subsequent chain reaction is initiated.

The sodium polyaspartate is used as a stabilizer of hydrogen peroxide, is a polypeptide carboxylic acid polymer, is a novel green water treatment agent, and has the characteristics of no phosphorus, no toxicity, no pollution and complete biodegradation. The sodium polyaspartate contains active groups such as amido bonds, carboxyl and the like, has strong chelation, dispersion, adsorption and other effects on ions, and can effectively prevent the corrosion of metal equipment. The sodium polyaspartate mainly adopts means of complexation, adsorption and synergistic effect of the two to destroy the hydroxide of metal ions, so that the metal ions lose catalytic activity, and the over-fast decomposition of hydrogen peroxide is effectively inhibited, thereby achieving the purpose of stabilizing the hydrogen peroxide.

Formic acid, glycolic acid and ethanol are free radical promoters in an ozone reaction system, the promoters mainly serve as carriers of chain reaction free radicals, so that the free radical reaction moves towards the direction of free radical generation, the reaction system is promoted to generate more hydroxyl free radicals, and the reaction speed of the system and the oxidation removal of pollutants are promoted.

The salicylic acid has the advantages of improving the oxidation efficiency of ozone in an acid environment, accelerating the decomposition of the ozone, and exciting the ozone to generate hydroxyl radicals to decompose pollutants.

The excitant and the accelerant in the enhancer have strong synergistic effect with the ozone.

The cleaning agent is composed of oxidizing gas ozone and a liquid reinforcer, and is combined with a novel cleaning method, so that the mechanical scouring and scrubbing effect of the ozone is utilized to the maximum extent, and the indirect oxidizing capability of the ozone is also utilized to the maximum extent. Under the action of the liquid reinforcer, ozone in the components generates hydroxyl radicals with oxidation capability far stronger than that of the ozone, and the hydroxyl radicals have extremely strong electron obtaining capability, namely oxidation capability, and oxidation potential of 2.8V. Is second only to fluorine in nature. Since the hydroxyl radical is present for a particularly short time, the reaction of the radical with the organic substance is a non-selective immediate reaction. A large amount of hydroxyl free radicals are generated in the cleaning process, so that a more ideal cleaning effect can be generated. Different from the comparison document, the ozone in the comparison document is used as an oxygen stabilizer to play a role in direct oxidation, the ozone and organic matters directly react, the selectivity is realized, only a certain type of organic matters can be directly aligned, the reaction speed is very low, and the cleaning is not facilitated.

Compared with the prior art, the invention has the beneficial effects that:

1) the selected reagent is a gas with strong oxidizing property as a main agent, two different reinforcers are used as cleaning aids in a combined way, physical and chemical characteristics are organically combined, and the cleaning efficiency and effect are greatly enhanced. The like products in the current market mostly use a single chemical agent as a main agent or single physical mechanical cleaning;

2) by utilizing the unique structure and characteristics of the ceramic membrane and adopting a reverse or forward and reverse combined input mode, the physical characteristics of ozone are changed, the catalytic decomposition potential of ozone is stimulated to the maximum extent, and the aims of comprehensive sterilization and thorough cleaning are fulfilled;

3) compared with the traditional cleaning agent, the cleaning agent is flexible in application, not only can be used for shutdown cleaning, but also has the characteristics of easy decomposition of a gas part and no residue, can be used for production and operation gap chemical backwashing, is wider in application range, can quickly and efficiently recover the flux and the operation efficiency of the ceramic membrane, and prolongs the cleaning period of a system and the service life of the membrane;

4) the selected reagent main agent ozone has the characteristics of strong oxidizing property, sterilization property, easy decomposition and no residue, and the auxiliary agent enhancer is green, non-phosphorus, non-toxic, pollution-free, capable of being completely biodegraded, environment-friendly and pollution-free. The method has strong universality and is suitable for various ceramic membrane systems.

Detailed Description

The present invention will be described in detail with reference to examples, but it should be noted that the practice of the present invention is not limited to the following embodiments.

Example 1:

the ceramic membrane cleaning agent is preferred, wherein:

the alkaline enhancer A is prepared from the following components in parts by weight, and is shown in Table 1;

table 1 example alkaline enhancer a formulation

Component (in parts)	Formulation 1	Formulation 2	Formulation 3
				Sodium hydroxide	15	13	8
Hydrogen peroxide solution	15	26	32
				Ethanol	24	18	12
Polyaspartic acid sodium salt	6	5	8
				Demineralized water	40	38	40

Preparing a basic enhancer A, wherein:

formula 1:

a sodium hydroxide solution was prepared from 15 parts of sodium hydroxide and 40 parts of demineralized water, and the sodium hydroxide solution was diluted with 24 parts of ethanol. Adding 15 parts of hydrogen peroxide into a reactor, and then cooling the hydrogen peroxide solution to 0 ℃ by using a low-temperature cooler. 6 parts of polyaspartic acid sodium and the diluted sodium hydroxide mixed solution are slowly added into the reactor in turn under stirring, and the reaction temperature is maintained at-3 ℃. The whole reaction process is carried out under vacuum.

And (2) formula:

a sodium hydroxide solution was prepared from 13 parts of sodium hydroxide and 38 parts of demineralized water, and the sodium hydroxide solution was diluted with 18 parts of ethanol. Adding 26 parts of hydrogen peroxide into a reactor, and then cooling the hydrogen peroxide solution to 0 ℃ by using a low-temperature cooler. 5 parts of polyaspartic acid sodium and the diluted sodium hydroxide mixed solution are slowly added into the reactor in sequence under stirring, and the reaction temperature is maintained at-2 ℃. The whole reaction process is carried out under vacuum.

And (3) formula:

a sodium hydroxide solution was prepared from 8 parts of sodium hydroxide and 40 parts of demineralized water, and the sodium hydroxide solution was diluted with 12 parts of ethanol. Adding 32 parts of hydrogen peroxide into a reactor, and then cooling the hydrogen peroxide solution to 0 ℃ by using a low-temperature cooler. 8 parts of polyaspartic acid sodium and the diluted sodium hydroxide mixed solution are slowly added into the reactor in sequence under stirring, and the reaction temperature is maintained at-5 ℃. The whole reaction process is carried out under vacuum.

The acid enhancer B is prepared by mixing and dissolving the following components in parts by weight, and is shown in Table 2;

TABLE 2 formulation of acid fortifier B of the examples

Component (in parts)	Formulation 4	Formulation 5	Formulation 6
				Formic acid	12	10	13
Glycolic acid	12	20	13
				Salicylic acid	24	15	13
Ethanol	16	24	26
				Water (W)	36	31	35

Preparing an acid enhancer B, wherein:

and (4) formula:

at normal temperature, 36 parts of desalted water, 16 parts of ethanol, 12 parts of formic acid, 24 parts of salicylic acid and 12 parts of glycolic acid are sequentially added into a reaction kettle and uniformly stirred and mixed.

And (5) formula:

at normal temperature, 31 parts of desalted water, 24 parts of ethanol, 10 parts of formic acid, 15 parts of salicylic acid and 20 parts of glycolic acid are sequentially added into a reaction kettle and uniformly stirred and mixed.

And (6) formula:

at normal temperature, 35 parts of demineralized water, 26 parts of ethanol, 13 parts of formic acid, 13 parts of salicylic acid and 13 parts of glycolic acid are sequentially added into a reaction kettle and uniformly stirred and mixed.

Preparing a cleaning agent required by an experiment, respectively dissolving the preferred six enhancers in clear water to prepare a cleaning solution with the content of 1 wt%, namely A1, A2, A3, B4, B5 and B6, and compared with the existing commercial cleaning agents C1 and C2, chemically cleaning the polluted membrane under the same condition for convenience of comparison. C1 is the mixture of 1.5 wt% sodium hydroxide and 0.1 wt% sodium hypochlorite, C2 is 1.5 wt% nitric acid solution.

Simulating the preparation and membrane pollution process of cold rolling emulsion oily wastewater:

according to the analysis result of the composition and the property of cold rolling oily wastewater in a certain factory, a high-shear dispersion emulsifying machine is adopted to disperse 20# engine oil and an emulsifying agent in water at a high speed according to a certain proportion to prepare an oil-water emulsion with the oil concentration of 5 g/L. 19-channel Al ceramic film used₂O₃Ceramic microfiltration membrane with 50nm of membrane aperture. Using 0.24m²The ceramic membrane filtration equipment carries out oily wastewater treatment in a cross-flow filtration mode, and the operation time (membrane pollution process) is 48 hours. The operating conditions were: the transmembrane pressure difference delta P is 0.05MPa, the membrane surface flow velocity is 4.2m/s, and the feed liquid temperature T is about 50 ℃.

Cleaning according to a cleaning method of a ceramic membrane cleaning agent:

wherein the cleaning steps of A1, A2 and A3 are as follows:

1) emptying materials, pre-washing with clear water, and washing loose dirt on the surface of the membrane cavity;

2) respectively heating the A1, the A2 and the A3 to 40 ℃;

3) cleaning for 5min without permeation circulation;

4) cleaning for 3min in a permeation circulation mode, stopping cleaning, reversely inputting ozone for 12min, and controlling the flow: 2.0L/min, pressure: 0.1 Mpa; the steps are repeated for 3 times, and the water is emptied and rinsed until the drained water is neutral.

B4, B5 and B6:

1) emptying materials, pre-washing with clear water, and washing loose dirt on the surface of the membrane cavity;

2) the above B4, B5 and B6 were heated to 30 ℃ respectively.

3) Cleaning for 5min without permeation circulation;

4) cleaning for 3min in a permeation circulation mode, stopping cleaning, reversely inputting ozone for 12min, and controlling the flow: 1.0L/min, pressure: 0.5 Mpa; repeating the steps for 2 times, emptying, rinsing with water until the water drainage is neutral, and finishing the cleaning process.

Cleaning methods of traditional cleaning agents such as C1 and C2:

wherein the washing step of C1:

1) washing with clear water;

2) heating to 60 deg.C with C1, and cleaning for 60 min. The permeable reflux valve is opened 5 minutes before cleaning, the permeable reflux valve is opened 5 minutes before stopping the machine, and the permeable reflux valve is closed in the rest time. And (5) emptying after the cleaning is finished, and rinsing the equipment to be neutral.

C2 washing step:

1) washing with clear water;

2) the mixture was heated to 30 ℃ and washed for 60min using C2. And the permeation reflux valve is opened in the first 5 minutes of cleaning, the permeation reflux valve is opened in the first 5 minutes of stopping the machine, and the permeation reflux valve is closed in the rest time. And (5) emptying after the cleaning is finished, and rinsing the equipment to be neutral.

The pure water flux recovery rate (FRw) and the oil-water permeability recovery rate (FRO) of the membrane after being cleaned by different detergents are shown in a table 3;

table 3 example 1, comparative example flux recovery comparison

Sample (I)	A1	A2	A3	B4	B5	B6	C1	C2
									FRw/％	93.7	90.2	96.5	86.9	82.6	81.9	87.2	73.7
FRo/％	94.5	92.1	97.6	88.0	83.8	83.2	88.3	74.4

It can be seen from table 3 that the pure water flux recovery rate and the oil-water permeation flux recovery rate of the membrane after the a3 cleaning are the highest, and the cleaning effect is the best.

Example 2:

in order to further verify the cleaning effect, industrial application experiments are also carried out on the ceramic membrane system of the cold-rolled emulsion oily wastewater in a certain rolling mill, and the water quality conditions are shown in table 4.

Table 4 practical conditions of example 2

pH	Oil (g/L)	COD(mg/L)	SS(mg/L)	Total iron (mg/L)
					8.3	4.51	13000	350	2.36

The combination of the ceramic membrane cleaning agents A3 and B4 and the combination of the traditional cleaning agents C1 and C2 are respectively used for cleaning two sets of polluted equipment with the same operation parameters.

The ceramic membrane cleaning agents A3 and B4 were combined and cleaned by the following cleaning methods:

1) emptying materials, pre-washing with clear water, and washing loose dirt on the surface of the membrane cavity;

2) heating the A3 to 40 ℃, cleaning for 5min without permeation circulation, cleaning for 3min with permeation circulation, stopping cleaning, reversely inputting ozone for 12min, and controlling the flow: 2.0L/min, pressure: 0.1 Mpa; repeating the steps for 3 times, emptying, and rinsing with water until the drained water is neutral;

3) heating the B4 to 30 ℃, cleaning for 5min without permeation circulation, cleaning for 3min with permeation circulation, stopping cleaning, reversely inputting ozone for 12min, and controlling the flow: 1.0L/min, pressure: 0.5 Mpa; repeating the steps for 2 times, emptying, rinsing with water until the water drainage is neutral, and finishing the cleaning process.

The traditional cleaning agent C1 and C2 combined cleaning method comprises the following steps:

1) washing with clear water;

2) heating to 60 deg.C with C1, and cleaning for 60 min. And the permeation reflux valve is opened in the first 5 minutes of cleaning, the permeation reflux valve is opened in the first 5 minutes of stopping the machine, and the permeation reflux valve is closed in the rest time. And (5) emptying after the cleaning is finished, and rinsing the equipment to be neutral.

3) The mixture was heated to 30 ℃ and washed for 60min using C2. And the permeation reflux valve is opened in the first 5 minutes of cleaning, the permeation reflux valve is opened in the first 5 minutes of stopping the machine, and the permeation reflux valve is closed in the rest time. And rinsing the equipment to be neutral, and finishing the cleaning. The pure water flux recovery and oil-water permeation flux recovery of the membrane after cleaning are shown in table 5.

Table 5 example 2, comparative example flux recovery comparison

Example 3:

to test the stability of the combined detergents A3 and B4, the same single set of equipment was washed for 6 cycles. The procedure was as in example 2.

The pure water flux recovery and oil-water permeation flux recovery of the membrane after cleaning are shown in table 6.

Table 6 example 3 flux recovery

As can be seen from table 6, the pure water flux recovery rate and the oil-water permeation flux recovery rate of the membrane after the cleaning from the 4 th cycle start were stable, and particularly, the oil-water permeation flux recovery rate was more than 97%. Reflects that the long-term existing stubborn dirt in the system is basically cleaned and finished, and achieves good effect.

The components of the cleaning agent have good synergy, so that the cleaning agent has excellent effect; the cleaning agent is flexible to combine and use, can be used for shutdown cleaning, has the characteristics of easy decomposability and no residue of an oxidizing gas part, can be used for production and operation gap chemical backwashing, has wide application range and strong universality, and is suitable for various different types of ceramic membrane systems; the cleaning agent has strong oxidizing property and sterilization property, and does not need to carry out additional sterilization treatment on a special ceramic membrane system needing regular sterilization; the cleaning agent is green, non-phosphorus, nontoxic, pollution-free and easy to decompose, can be completely biodegraded, and does not harm the environment.