Preparation method of modified filter membrane and application of modified filter membrane in soy sauce wastewater treatment

Abstract

The invention relates to a preparation method of a modified filter membrane, which comprises the following steps: adding modified titanium dioxide nanoparticles into a solvent, carrying out ultrasonic dispersion, adding PAN (Polyacrylonitrile), modified polyether sulfone and PEG (Polyethylene Glycol) into the solvent, heating and stirring, and standing to obtain a membrane casting solution; immersing the surface of a glass plate into the membrane casting solution, scraping the glass plate with a scraper, volatilizing the solvent, and soaking the glass plate carrying the membrane casting solution in water to obtain a modified filter membrane; wherein the modified titanium dioxide nano particles are titanium dioxide nano particles of which the surfaces are grafted with 8-hydroxycaprylic acid; the modified polyether sulfone is polyether sulfone grafted with PEG (Polyethylene Glycol). Long-chain alkyl groups and hydrophilic hydroxyl groups are grafted on the modified titanium dioxide nanoparticles, so that the agglomeration phenomenon of the modified titanium dioxide nanoparticles can be slowed down and inhibited, and the dispersity of the modified titanium dioxide nanoparticles in the components is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a preparation method of a modified filter membrane and application of the modified filter membrane in treating soy sauce wastewater. Background Art

[0002] With the rapid development of industry, wastewater discharge has become an important issue of environmental protection, especially the large amount of high-concentration organic wastewater generated by food processing industries such as soy sauce. Soy sauce wastewater contains grain residues, fermentation products, soy sauce pigments, disinfectants, a large amount of salt, various microorganisms and their secretions and metabolites, etc. It has the characteristics of high chromaticity and high ammonia nitrogen concentration. In addition, due to its dark color and high salt content, direct discharge will cause serious damage to the ecological environment of the water body. Therefore, how to efficiently and economically treat soy sauce wastewater has become a problem that needs to be solved urgently.

[0003] At present, commonly used wastewater treatment methods include biological treatment, chemical treatment and physical treatment. However, traditional biological treatment has limited effect on soy sauce wastewater treatment, while chemical treatment may introduce secondary pollution. Therefore, membrane separation technology has shown broad application prospects in the field of soy sauce wastewater treatment due to its advantages such as high efficiency, environmental protection and no need for chemical agents.

[0004] In membrane separation technology, the performance of the filter membrane directly determines the separation effect. However, in the process of treating soy sauce wastewater, traditional filter membranes are easily polluted and blocked by organic matter and salt, resulting in reduced flux and shortened service life. Therefore, the development of modified filter membranes with anti-pollution performance and excellent separation effect has become one of the key research directions.

[0005] In order to meet these challenges, the introduction of nanomaterials in recent years has provided new ideas for modifying filter membranes. In particular, titanium dioxide nanoparticles have gradually become one of the ideal materials for filter membrane modification due to their excellent antibacterial and anti-pollution properties. However, despite the excellent performance of titanium dioxide nanoparticles, there are still some problems in their practical applications. For example, nanoparticles tend to agglomerate in water, resulting in poor dispersibility and difficulty in evenly distributing them in membrane materials. This uneven distribution not only affects the separation effect of the membrane, but may also cause clogging of the membrane pores, resulting in a poor treatment effect on soy sauce wastewater.

[0006] Therefore, it is necessary to develop a new technical solution to solve the deficiencies in the prior art. Summary of the invention

[0007] Based on this, the present invention provides a preparation method of a modified filter membrane and its application in treating soy sauce wastewater, and improves the effect and efficiency of treating soy sauce wastewater by functionally modifying the membrane material. The method adopts modified titanium dioxide nanoparticles, which have excellent anti-pollution performance, can not only inhibit the deposition of pollutants on the membrane surface, but also degrade some organic pollutants in the treatment of soy sauce wastewater, reducing the pollution burden on the membrane surface. In addition, by grafting polyethylene glycol (PEG) on polyethersulfone, the hydrophilicity of the membrane is significantly improved, and the adsorption of hydrophobic pollutants is reduced.

[0008] An object of the present invention is to provide a method for preparing a modified filter membrane, comprising the following steps: adding modified titanium dioxide nanoparticles to a solvent, ultrasonically dispersing, adding PAN (polyacrylonitrile), modified polyethersulfone and PEG thereto, heating and stirring, and then standing to obtain a casting solution;

[0009] The casting solution is immersed on the surface of the glass plate, and the glass plate is scraped with a scraper. After the solvent is volatilized, the glass plate carrying the casting solution is immersed in water to obtain a modified filter membrane;

[0010] Wherein, the modified titanium dioxide nanoparticles are titanium dioxide nanoparticles whose surfaces are grafted with 8-hydroxyoctanoic acid;

[0011] The modified polyethersulfone is polyethersulfone grafted with PEG.

[0012] Furthermore, the preparation method of the modified polyethersulfone is: dissolving polyethersulfone in a solvent, adding a mixture of chlorosulfonic acid and chloroform, heating to react, removing the lower precipitate, adding a chloroform solution of PEG, reacting at room temperature to obtain the modified polyethersulfone.

[0013] Furthermore, the preparation method of the modified titanium dioxide nanoparticles is:

[0014] S1-1, adding titanium dioxide nanoparticles into hydrogen peroxide, heating for reaction, and obtaining hydroxylated titanium dioxide nanoparticles;

[0015] S1-2, immersing the hydroxylated titanium dioxide nanoparticles in an 8-hydroxyoctanoic acid solution, heating and ultrasonicating, to obtain the modified titanium dioxide nanoparticles.

[0016] Furthermore, the mass ratio of the modified titanium dioxide nanoparticles, PAN, modified polyethersulfone and PEG is: 2-4:10-14:3-5:4-6.

[0017] Furthermore, in step S1-1, the heating temperature is 80-85°C.

[0018] Furthermore, the soaking condition is: the deionized water is changed every 12-20 hours, and the soaking process lasts for 3-7 days.

[0019] Furthermore, the molecular weight of the polyethersulfone is 50,000-80,000.

[0020] Furthermore, the PEG is selected from one or more of PEG400, PEG1000, and PEG2000.

[0021] The present invention also provides application of the modified filter membrane prepared by the preparation method of the modified filter membrane in treating soy sauce wastewater.

[0022] Furthermore, the thickness of the modified filter membrane is 130-160 μm.

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

[0024] The invention provides a modified filter membrane, wherein titanium dioxide nanoparticles are first subjected to hydroxylation pretreatment, and then reacted with 8-hydroxyoctanoic acid to introduce alkyl chains and hydroxyl groups into the titanium dioxide nanoparticles to obtain modified titanium dioxide nanoparticles; polyethersulfone is subjected to sulfonation reaction with chlorosulfonic acid, and then reacted with PEG to introduce PEG into the polyethersulfone to obtain modified polyethersulfone; and the modified titanium dioxide nanoparticles, PAN, the modified polyethersulfone and PEG are reacted to introduce the modified titanium dioxide nanoparticles into the filter membrane; on the one hand, since long-chain alkyl and hydroxyl groups are grafted onto the modified titanium dioxide nanoparticles, the agglomeration phenomenon of the modified titanium dioxide nanoparticles can be slowed down and inhibited, and the dispersibility of the modified titanium dioxide nanoparticles in the components can be improved; and at the same time, since the filter membrane is rich in hydroxyl groups, the hydrophilicity and permeability of the filter membrane can be effectively improved. On the other hand, since PEG groups are grafted on polyethersulfone, the hydrophilicity of polyethersulfone can be effectively improved, reducing the adsorption of hydrophobic pollutants in soy sauce wastewater, which is beneficial to improving the anti-pollution ability of the filter membrane, thereby effectively improving the removal of pollutants in soy sauce wastewater by the filter membrane; secondly, the modified titanium dioxide nanoparticles and modified polyethersulfone contain a large number of hydroxyl groups that can form hydrogen bonds with water molecules to form a hydrated film on the surface of the filter membrane, which can further improve the hydrophilicity and anti-pollution properties of the filter membrane surface, thereby effectively treating soy sauce wastewater. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the technical solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0026] The words "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0027] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers indicating, for example, the amounts of ingredients used in the specification and claims should be understood to be modified in all cases by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary depending on the desired properties to be obtained by the present invention.

[0028] PEG1 and PEG1000 were purchased from Jining Fangyu Chemical Co., Ltd.

[0029] PEG2 and PEG400 were purchased from Tianjin Damao Chemical Reagent Factory.

[0030] PEG3, PEG2000, purchased from Merck.

[0031] PES, polyethersulfone, Mw=75000, Ultrason E 6020P, available from BASF.

[0032] PAN, polyacrylonitrile, Mw=150,000, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0033] Titanium dioxide nanoparticles, with a particle size of 20 nm, were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0034] DMAc, N,N-dimethylacetamide.

[0035] The "parts" in the embodiments of the present invention refer to parts by mass.

[0036] Example 1

[0037] A modified filter membrane, the preparation method of the modified filter membrane comprising the following steps: adding 2 parts of modified titanium dioxide nanoparticles to 76 parts of DMAc, ultrasonically dispersing for 1 hour, then adding 13.5 parts of PAN, 3.5 parts of modified polyethersulfone and 5 parts of PEG1 thereto, heating to 80°C and stirring for 12 hours, and then standing for 24 hours to obtain a casting solution;

[0038] The casting solution is immersed on the surface of the glass plate, and a scraper is used to scrape the glass plate to make the filter membrane thickness 150 μm. After the solvent is volatilized, the glass plate carrying the casting solution is immersed in deionized water for 72 hours, and the deionized water is replaced every 12 hours to obtain a modified filter membrane;

[0039] The preparation method of the modified polyethersulfone is as follows: 2 parts of polyethersulfone are dissolved in 20 parts of chloroform, stirred for 20 minutes, cooled, then added with a mixed solution containing 1.5 parts of chlorosulfonic acid and 10 parts of chloroform, heated to 85°C for reaction for 12 hours, the lower precipitate is removed, then added with a mixed solution containing 2.5 parts of PEG2 and 20 parts of chloroform, reacted at room temperature for 4 hours, and the modified polyethersulfone is obtained;

[0040] The preparation method of the modified titanium dioxide nanoparticles is:

[0041] S1-1, mixing 5 parts of titanium dioxide nanoparticles with 100 parts of 30 wt% hydrogen peroxide, reacting at 85° C. for 6 h, filtering, washing, and drying to obtain hydroxylated titanium dioxide nanoparticles;

[0042] S1-2, adding the hydroxylated titanium dioxide nanoparticles to 80 parts of ethanol, and then adding 10 parts of 8-hydroxyoctanoic acid, heating and ultrasonicating at 80° C. for 3 hours, filtering, washing and drying to obtain modified titanium dioxide nanoparticles.

[0043] Example 2

[0044] A modified filter membrane, the preparation method of the modified filter membrane comprising the following steps: adding 2 parts of modified titanium dioxide nanoparticles to 76 parts of DMAc, ultrasonically dispersing for 1 hour, then adding 13.5 parts of PAN, 3.5 parts of modified polyethersulfone and 5 parts of PEG1 thereto, heating to 75°C and stirring for 14 hours, and then standing for 24 hours to obtain a casting solution;

[0045] The casting solution is immersed on the surface of the glass plate, and the filter membrane is scraped on the glass plate with a scraper to make the filter membrane thickness 130 μm. After the solvent is volatilized, the glass plate carrying the casting solution is immersed in deionized water for 100 hours, and the deionized water is replaced every 15 hours to obtain a modified filter membrane;

[0046] The preparation method of the modified polyethersulfone is as follows: 2 parts of polyethersulfone are dissolved in 20 parts of chloroform, stirred for 30 minutes, cooled, then added with a mixed solution containing 1.5 parts of chlorosulfonic acid and 10 parts of chloroform, heated to 80°C for reaction for 12 hours, the lower precipitate is removed, then added with a mixed solution containing 2.5 parts of PEG2 and 20 parts of chloroform, reacted at room temperature for 6 hours, and the modified polyethersulfone is obtained;

[0047] The preparation method of the modified titanium dioxide nanoparticles is:

[0048] S1-1, mixing 5 parts of titanium dioxide nanoparticles with 100 parts of 30 wt% hydrogen peroxide, reacting at 85° C. for 6 h, filtering, washing, and drying to obtain hydroxylated titanium dioxide nanoparticles;

[0049] S1-2, adding the hydroxylated titanium dioxide nanoparticles to 90 parts of ethanol, and then adding 10 parts of 8-hydroxyoctanoic acid, heating and ultrasonicating at 80° C. for 3 hours, filtering, washing and drying to obtain modified titanium dioxide nanoparticles.

[0050] Example 3

[0051] A modified filter membrane, the preparation method of the modified filter membrane comprising the following steps: adding 2 parts of modified titanium dioxide nanoparticles to 76 parts of DMAc, ultrasonically dispersing for 1.5 hours, then adding 13.5 parts of PAN, 3.5 parts of modified polyethersulfone and 5 parts of PEG1 thereto, heating to 80°C and stirring for 12 hours, and then standing for 24 hours to obtain a casting solution;

[0052] The casting solution is immersed on the surface of the glass plate, and the filter membrane is scraped on the glass plate with a scraper to make the filter membrane thickness 150 μm. After the solvent is volatilized, the glass plate carrying the casting solution is immersed in deionized water for 120 hours, and the deionized water is replaced every 20 hours to obtain a modified filter membrane;

[0053] The preparation method of the modified polyethersulfone is as follows: 2 parts of polyethersulfone are dissolved in 20 parts of chloroform, stirred for 35 minutes, cooled, then added with a mixed solution containing 1.5 parts of chlorosulfonic acid and 10 parts of chloroform, heated to 85°C for reaction for 12 hours, the lower precipitate is removed, then added with a mixed solution containing 2.5 parts of PEG3 and 20 parts of chloroform, reacted at room temperature for 6 hours, and the modified polyethersulfone is obtained;

[0054] The preparation method of the modified titanium dioxide nanoparticles is:

[0055] S1-1, mixing 5 parts of titanium dioxide nanoparticles with 100 parts of 35 wt% hydrogen peroxide, reacting at 80° C. for 7 h, filtering, washing, and drying to obtain hydroxylated titanium dioxide nanoparticles;

[0056] S1-2, adding the hydroxylated titanium dioxide nanoparticles to 100 parts of ethanol, and then adding 10 parts of 8-hydroxyoctanoic acid, heating and ultrasonicating at 85° C. for 3 hours, filtering, washing and drying to obtain modified titanium dioxide nanoparticles.

[0057] Comparative Example 1

[0058] A filter membrane. The difference between this comparative example and Example 1 is that step S1-1 is removed, and the mass of modified titanium dioxide nanoparticles is replaced by hydroxylated titanium dioxide nanoparticles. Other components and preparation methods are the same as those in Example 1.

[0059] Comparative Example 2

[0060] A filter membrane. The difference between this comparative example and Example 1 is that the modified polyethersulfone is replaced by unmodified polyethersulfone, and the other components and preparation method are the same as those in Example 1.

[0061] Test Case

[0062] The performance of the filter membranes prepared in Example 1 and Comparative Examples 1-2 was tested.

[0063] The test method is as follows:

[0064] COD test method:

[0065] The COD removal rate and ammonia nitrogen removal rate of soy sauce wastewater with a COD value of 1190 mg / L, ammonia nitrogen concentration of 127 mg / L, chromaticity of 500 times, and pH value of 7 (Source: Heshan Donggu Condiment Food Co., Ltd.; Address: No. 3, Maishui Industrial Zone, Gulao Town, Heshan City, Guangdong Province;) after passing through the filter membrane were tested;

[0066] Chroma: Refer to the dilution multiple method in the "China Environmental Protection Standard Compilation - Water Quality Analysis Method" (4th Edition) to test the chroma of soy sauce wastewater with a chroma of 500 times after passing through the filter membrane;

[0067] Contact angle test:

[0068] Deionized water was dropped on the surface of the filter membrane, and the contact angle was measured using a DSA30 contact angle tester.

[0069] The test results are shown in Table 1.

[0070] Table 1 Performance test results

[0071] project Example 1 Comparative Example 1 Comparative Example 2 COD removal rate (%) 78 66 59 Ammonia nitrogen removal rate (%) 37 32 28 Chroma(times) ＜40 ＞60 ＞100 Contact angle (°) 61.8 68.5 74.3

[0072] It can be seen from Table 1 that the filter membrane of Example 1 of the present invention has an excellent contact angle, COD removal rate for soy sauce wastewater, ammonia nitrogen removal rate, and chromaticity that are significantly better than those of the comparative example.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0074] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a modified filter membrane, characterized in that: The method comprises the following steps: adding modified titanium dioxide nanoparticles into a solvent, dispersing by ultrasonic, adding PAN, modified polyethersulfone and PEG into the solvent, heating and stirring, and then standing to obtain a casting solution; The casting solution is immersed on the surface of the glass plate, and the glass plate is scraped with a scraper. After the solvent is volatilized, the glass plate carrying the casting solution is immersed in water to obtain a modified filter membrane; Wherein, the modified titanium dioxide nanoparticles are titanium dioxide nanoparticles whose surfaces are grafted with 8-hydroxyoctanoic acid; The modified polyethersulfone is polyethersulfone grafted with PEG.

2. The method for preparing the modified filter membrane according to claim 1, characterized in that: The preparation method of the modified polyethersulfone is as follows: dissolving the polyethersulfone in a solvent, adding a mixed solution of chlorosulfonic acid and chloroform, heating for reaction, taking a lower precipitate, adding a chloroform solution of PEG, reacting at room temperature, and obtaining the modified polyethersulfone.

3. The method for preparing the modified filter membrane according to claim 1, characterized in that: The preparation method of the modified titanium dioxide nanoparticles is: S1-1, adding titanium dioxide nanoparticles into hydrogen peroxide, heating for reaction, and obtaining hydroxylated titanium dioxide nanoparticles; S1-2, immersing the hydroxylated titanium dioxide nanoparticles in an 8-hydroxyoctanoic acid solution, heating and ultrasonicating, to obtain the modified titanium dioxide nanoparticles.

4. The method for preparing the modified filter membrane according to claim 1, characterized in that: The mass ratio of the modified titanium dioxide nanoparticles, PAN, modified polyethersulfone and PEG is: 2-4:10-14:3-5:4-6.

5. The method for preparing the modified filter membrane according to claim 3, characterized in that: In step S1-1, the heating temperature is 80-85°C.

6. The method for preparing the modified filter membrane according to claim 1, characterized in that: The soaking conditions are as follows: deionized water is replaced every 12-20 hours, and the soaking process lasts for 3-7 days.

7. The method for preparing the modified filter membrane according to claim 1, characterized in that: The molecular weight of the polyethersulfone is 50,000-80,000.

8. The method for preparing the modified filter membrane according to any one of claims 1 to 2, characterized in that: The PEG is selected from one or more of PEG400, PEG1000, and PEG2000.

9. Application of the modified filter membrane prepared by the preparation method of the modified filter membrane according to claim 1 in treating soy sauce wastewater.

10. Application of the modified filter membrane prepared by the preparation method of the modified filter membrane according to claim 9 in treating soy sauce wastewater, characterized in that: The thickness of the modified filter membrane is 130-160 μm.