Preparation method of a modified filter membrane and its application in treating soy sauce wastewater

Abstract

The present invention relates to a preparation method of a modified filter membrane, which comprises the following steps: adding modified titanium dioxide nanoparticles into a solvent, ultrasonically dispersing, then adding PAN, modified polyethersulfone and PEG thereto, heating and stirring, and then standing to obtain a casting solution; immersing the surface of a glass plate into the casting solution, scraping on the glass plate with a scraper, and after volatilizing the solvent, soaking the glass plate carrying the casting solution in water to obtain a modified filter membrane; wherein, the modified titanium dioxide nanoparticles are titanium dioxide nanoparticles grafted with 8-hydroxyoctanoic acid on the surface; the modified polyethersulfone is polyethersulfone grafted with PEG. Since long-chain alkyl groups and hydrophilic hydroxyl groups are grafted on 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.

Description

Technical Field

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

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

[0003] Currently, the commonly used wastewater treatment methods include biological treatment, chemical treatment and physical treatment. However, traditional biological treatment has limited treatment effect on soy sauce wastewater, while chemical treatment may introduce secondary pollution. Therefore, membrane separation technology shows 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, during the process of treating soy sauce wastewater, traditional filter membranes are easily contaminated and blocked by organic matters and salts, resulting in a decrease in flux and a shortening of service life. Therefore, developing modified filter membranes with anti-pollution performance and excellent separation effect has become one of the key research directions.

[0005] In order to address these challenges, in recent years, the introduction of nanomaterials has provided new ideas for modified 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, although titanium dioxide nanoparticles have excellent properties, there are still some problems in their practical applications. For example, nanoparticles are prone to agglomeration in water, resulting in poor dispersibility and difficulty in being evenly distributed in the membrane material. This uneven distribution will not only affect the separation effect of the membrane, but may also lead to membrane pore blockage, resulting in a worse 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 method for preparing a modified filter membrane and its application in treating soy sauce wastewater. By functionalizing and modifying the membrane material, the treatment effect and efficiency for soy sauce wastewater are improved. This method uses modified titanium dioxide nanoparticles, which have excellent anti-pollution performance. They 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) onto polyethersulfone, the hydrophilicity of the membrane is significantly improved, reducing the adsorption of hydrophobic pollutants.

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

[0009] Immerse the surface of a glass plate into the casting solution, scrape it on the glass plate with a scraper, after volatilizing the solvent, immerse the glass plate carrying the casting solution in water to obtain the modified filter membrane;

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

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

[0012] Further, the preparation method of the modified polyethersulfone is: dissolving polyethersulfone in a solvent, then adding a mixed solution of chlorosulfonic acid and chloroform, heating and reacting, taking the lower-layer precipitate, and then adding a chloroform solution of PEG, reacting at room temperature to obtain the modified polyethersulfone.

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

[0014] S1-1: Adding titanium dioxide nanoparticles into hydrogen peroxide, heating and reacting to obtain hydroxylated titanium dioxide nanoparticles;

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

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

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

[0018] Further, the conditions for soaking are as follows: deionized water is changed every 12 - 20 h, and the soaking process lasts for 3 - 7 d.

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

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

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

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

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

[0024] The present invention provides a modified filter membrane. First, the titanium dioxide nanoparticles are subjected to hydroxylation pretreatment, and then reacted with 8-hydroxyoctanoic acid to introduce alkyl chains and hydroxyl groups into the titanium dioxide nanoparticles, obtaining modified titanium dioxide nanoparticles; through the sulfonation reaction of polyethersulfone with chlorosulfonic acid, and then reacting with PEG to introduce PEG onto the polyethersulfone, obtaining modified polyethersulfone; then, through the reaction of modified titanium dioxide nanoparticles, PAN, modified polyethersulfone, and PEG, the modified titanium dioxide nanoparticles are introduced into the filter membrane. On the one hand, since the modified titanium dioxide nanoparticles are grafted with long-chain alkyl and hydroxyl groups, 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; 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 the polyethersulfone is grafted with PEG groups, the hydrophilicity of the polyethersulfone can be effectively improved, the adsorption of hydrophobic pollutants in soy sauce wastewater can be reduced, which is beneficial to enhancing the anti-pollution property of the filter membrane, thereby effectively improving the removal of pollutants in soy sauce wastewater by the filter membrane; secondly, a large number of hydroxyl groups on the modified titanium dioxide nanoparticles and the modified polyethersulfone can form hydrogen bonds with water molecules to form a hydration membrane on the surface of the filter membrane, which can further improve the surface hydrophilicity and anti-pollution property of the filter membrane, thereby realizing the effective treatment of soy sauce wastewater. Specific Embodiments

[0025] In order to more clearly illustrate the technical solutions of the present invention, the following examples are listed. The raw materials, reactions, and post-treatment means appearing in the examples are all common raw materials on the market and technical means well-known to those skilled in the art, unless otherwise specified.

[0026] The terms "preferred", "preferably", "more preferred", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects under certain circumstances. However, under the same circumstances or other circumstances, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, 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 instance or otherwise indicated, all numbers representing amounts of ingredients or otherwise used in the specification and claims, should be understood to be modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that vary depending upon the desired properties sought to be obtained by the present invention.

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

[0029] PEG2, PEG400, was purchased from Tianjin Damao Chemical Reagent Factory.

[0030] PEG3, PEG2000, was purchased from Merck.

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

[0032] PAN, polyacrylonitrile, Mw = 150000, was purchased from Shanghai Macklin Biochemical Co., Ltd.

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

[0034] DMAc, N,N-dimethylacetamide.

[0035] All "parts" in the examples 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 h, 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 h, and then standing for 24 h to obtain a casting solution;

[0038] Immerse the casting solution on the surface of the glass plate, scrape it on the glass plate with a scraper to make the filter membrane thickness 150 μm. After volatilizing the solvent, immerse the glass plate carrying the casting solution in deionized water for 72 h, and change the deionized water every 12 h to obtain a modified filter membrane;

[0039] The preparation method of the modified polyethersulfone is as follows: Dissolve 2 parts of polyethersulfone in 20 parts of chloroform, stir for 20 min, after cooling, add a mixed solution containing 1.5 parts of chlorosulfonic acid and 10 parts of chloroform, heat to 85 °C and react for 12 h, take the lower layer precipitate, and then add a mixed solution containing 2.5 parts of PEG2 and 20 parts of chloroform, react at room temperature for 4 h to obtain the modified polyethersulfone;

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

[0041] S1-1: Mix 5 parts of titanium dioxide nanoparticles with 100 parts of 30 wt% hydrogen peroxide, react at 85 °C for 6 h, filter, wash, and dry to obtain hydroxylated titanium dioxide nanoparticles;

[0042] S1-2: Add the hydroxylated titanium dioxide nanoparticles to 80 parts of ethanol, then add 10 parts of 8-hydroxyoctanoic acid, heat and ultrasonically react at 80 °C for 3 h, filter, wash, and dry to obtain the modified titanium dioxide nanoparticles.

[0043] Example 2

[0044] A modified filter membrane, the preparation method of the modified filter membrane includes the following steps: Add 2 parts of modified titanium dioxide nanoparticles to 76 parts of DMAc, ultrasonically disperse for 1 h, then add 13.5 parts of PAN, 3.5 parts of modified polyethersulfone and 5 parts of PEG1, heat to 75 °C and stir for 14 h, then let stand for 24 h to obtain a casting solution;

[0045] Immerse the casting solution on the surface of the glass plate, scrape it on the glass plate with a scraper to make the filter membrane thickness 130 μm. After volatilizing the solvent, immerse the glass plate carrying the casting solution in deionized water for 100 h, and change the deionized water every 15 h to obtain a modified filter membrane;

[0046] The preparation method of the modified polyethersulfone is as follows: Dissolve 2 parts of polyethersulfone in 20 parts of chloroform, stir for 30 min, after cooling, add a mixed solution containing 1.5 parts of chlorosulfonic acid and 10 parts of chloroform, heat to 80 °C and react for 12 h, take the lower layer precipitate, and then add a mixed solution containing 2.5 parts of PEG2 and 20 parts of chloroform, react at room temperature for 6 h to obtain the modified polyethersulfone;

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

[0048] S1-1. Mix 5 parts of titanium dioxide nanoparticles with 100 parts of 30 wt% hydrogen peroxide, react at 85 °C for 6 h, filter, wash, and dry to obtain hydroxylated titanium dioxide nanoparticles;

[0049] S1-2. Add the hydroxylated titanium dioxide nanoparticles to 90 parts of ethanol, then add 10 parts of 8-hydroxyoctanoic acid, heat and ultrasonically treat at 80 °C for 3 h, filter, wash, and dry to obtain modified titanium dioxide nanoparticles.

[0050] Example 3

[0051] A modified filter membrane, the preparation method of the modified filter membrane includes the following steps: Add 2 parts of modified titanium dioxide nanoparticles to 76 parts of DMAc, ultrasonically disperse for 1.5 h, then add 13.5 parts of PAN, 3.5 parts of modified polyethersulfone, and 5 parts of PEG1 thereto, heat to 80 °C and stir for 12 h, then let stand for 24 h to obtain a casting solution;

[0052] Immerse the surface of the glass plate in the casting solution, scrape on the glass plate with a scraper to make the thickness of the filter membrane 150 μm. After volatilizing the solvent, place the glass plate carrying the casting solution in deionized water and soak for 120 h, changing the deionized water every 20 h to obtain a modified filter membrane;

[0053] The preparation method of the modified polyethersulfone is as follows: Dissolve 2 parts of polyethersulfone in 20 parts of chloroform, stir for 35 min, after cooling, add a mixed solution containing 1.5 parts of chlorosulfonic acid and 10 parts of chloroform, heat to 85 °C and react for 12 h, take the lower layer precipitate, then add a mixed solution containing 2.5 parts of PEG3 and 20 parts of chloroform, and react at room temperature for 6 h to obtain modified polyethersulfone;

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

[0055] S1-1. Mix 5 parts of titanium dioxide nanoparticles with 100 parts of 35 wt% hydrogen peroxide, react at 80 °C for 7 h, filter, wash, and dry to obtain hydroxylated titanium dioxide nanoparticles;

[0056] S1-2. Add the hydroxylated titanium dioxide nanoparticles to 100 parts of ethanol, then add 10 parts of 8-hydroxyoctanoic acid, heat and ultrasonically treat at 85 °C for 3 h, filter, wash, and dry 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: Remove step S1-1, replace the modified titanium dioxide nanoparticles with an equal mass of hydroxylated titanium dioxide nanoparticles, and the 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 with unmodified polyethersulfone in equal mass, and other components and preparation methods are the same as those in Example 1.

[0061] Test Example

[0062] Perform performance tests on the filter membranes prepared in Example 1 and Comparative Examples 1-2.

[0063] The test method is as follows:

[0064] COD test method:

[0065] Test the COD removal rate and ammonia nitrogen removal rate of soy sauce wastewater with a COD value of 1190 mg / L, an ammonia nitrogen concentration of 127 mg / L, a chromaticity of 500 times, and a pH value of 7 (source: Heshan Donggu Flavoring Food Co., Ltd.; address: No. 3, Maishui Industrial Zone, Gulaotown, Heshan City, Guangdong Province;) after passing through the filter membrane;

[0066] Chromaticity: Refer to the dilution multiple method in "Compilation of Chinese Environmental Protection Standards - Analytical Water Quality Methods" (4th edition) to test the chromaticity of soy sauce wastewater with a chromaticity of 500 times after passing through the filter membrane;

[0067] Contact angle test:

[0068] Drop deionized water on the surface of the filter membrane and use a DSA30 contact angle tester to measure the contact angle.

[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 Colority (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 excellent contact angle, COD removal rate, ammonia nitrogen removal rate, and chromaticity for soy sauce wastewater, which are significantly better than those of the comparative examples.

[0073] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims within the present invention.

[0074] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A preparation method of a modified filter membrane, characterized in that It includes the following steps: adding modified titanium dioxide nanoparticles into a solvent, ultrasonically dispersing, then adding PAN, modified polyethersulfone and PEG thereto, heating and stirring, and then standing to obtain a casting solution; Immersing the surface of a glass plate into the casting solution, scraping on the glass plate with a scraper, after volatilizing the solvent, immersing the glass plate carrying the casting solution into water to obtain a modified filter membrane; Wherein, the modified titanium dioxide nanoparticles are titanium dioxide nanoparticles grafted with 8-hydroxyoctanoic acid on the surface; The modified polyethersulfone is polyethersulfone grafted with PEG; The mass ratio of the modified titanium dioxide nanoparticles, PAN, modified polyethersulfone and PEG is: 2-4:10-14:3-5:4-6.

2. The preparation method of the modified filter membrane according to claim 1, wherein, The preparation method of the modified polyethersulfone is: dissolving polyethersulfone in a solvent, adding a mixed solution of chlorosulfonic acid and chloroform, heating and reacting, taking the lower layer precipitate, and then adding a chloroform solution of PEG, reacting at room temperature to obtain the modified polyethersulfone.

3. The preparation method of 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 and reacting to obtain hydroxylated titanium dioxide nanoparticles; S1-2: soaking the hydroxylated titanium dioxide nanoparticles in an 8-hydroxyoctanoic acid solution, heating and ultrasonicating to obtain the modified titanium dioxide nanoparticles.

4. The preparation method of the modified filter membrane according to claim 3, wherein, In step S1-1, the heating temperature is 80-85 °C.

5. The preparation method of the modified filter membrane according to claim 1, wherein The soaking conditions are: changing deionized water every 12-20 h, and the soaking process lasts for 3-7 d.

6. The preparation method of the modified filter membrane according to claim 1, characterized in that, The molecular weight of the polyethersulfone is 50000-80000.

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

8. 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.

9. Use of the modified filter membrane prepared by the preparation method of the modified filter membrane according to claim 8 in treating soy sauce wastewater, characterized in that, The thickness of the modified filter membrane is 130-160 μm.