Preparation method of MBBR filler and MBBR filler

Abstract

The present application belongs to the technical field of mobile bed biological membrane reactor, and discloses a preparation method of MBBR filler and the MBBR filler.The preparation method of the MBBR filler disclosed by the present application comprises the following steps: S1, mixing polyolefin, chitosan and maleic anhydride grafted polyolefin, melting, extruding, shaping, and obtaining first filler; S2, dispersing the first filler in step S1 into an organic solvent, adding an anthraquinone compound containing anhydride, reacting, filtering, washing, and drying to obtain the MBBR filler.The MBBR filler obtained by the preparation method provided by the present application has good mechanical strength, hydrophilicity, biocompatibility and biofilm performance, and has good application prospect.

Description

Technical Field

[0001] This invention belongs to the technical field of moving bed biofilm reactors, and particularly relates to a method for preparing MBBR packing material and MBBR packing material. Background Technology

[0002] Moving bed biofilm reactors (MBBRs) are completely mixed and continuously operating biofilm reactors developed based on fluidized bed reactors and biological contact oxidation methods. In the treatment of low-concentration, high-volume wastewater (such as aquaculture wastewater) or wastewater containing toxic substances and recalcitrant organic matter (such as medical wastewater), MBBRs overcome the problems of traditional biofilm technologies, such as the need for periodic backwashing in aerated biological tanks, the large footprint of biological rotating discs, and the high energy consumption of high-density sulfurization on sulfurized bed carriers. MBBRs offer significant advantages in these applications.

[0003] MBBR packing provides a suitable growth and reproduction environment for microorganisms used in water treatment. The chemical properties, surface roughness, pore structure, specific surface area, and material type of the packing all affect the structure and performance of the biofilm, ultimately influencing the wastewater treatment effect of MBBR and forming the core technology of the MBBR process. Based on the material type, MBBR packing can be divided into inorganic packing, organic polymer packing, and natural biodegradable polymer packing. Compared to inorganic and natural biodegradable polymer packing, organic polymer packing has higher mechanical strength, a smaller density difference with water, and is easier to handle, making it the most widely used type of packing in MBBR.

[0004] However, in practical applications, it has been found that the effect of organic polymer fillers in treating wastewater is not ideal. They have problems such as low hydrophilicity, poor biocompatibility, slow biofilm formation speed, and poor biofilm formation effect, which have significant limitations. Summary of the Invention

[0005] In MBBR (Metal-Oxygen Bioreactor) processes, organic polymer fillers are the most widely used type of filler due to their advantages such as high mechanical strength, density similar to water, and ease of operation. However, the surfaces of organic polymer materials such as polyethylene and polypropylene are enriched with non-polar groups, have low surface energy, and are mostly smooth, which is not conducive to microbial adhesion. Therefore, organic polymer fillers suffer from problems such as low speed and poor effect in the biofilm formation process.

[0006] Based on the problems existing in existing organic polymer fillers, the inventors of this application, through extensive and in-depth research and numerous experiments, discovered that by using chitosan and maleic anhydride-grafted polyolefins to jointly modify polyolefins, and then using anthraquinone compounds containing anhydrides to modify the first filler, the synergistic modification effect of chitosan, maleic anhydride-grafted polyolefins, and anthraquinone compounds containing anhydrides on polyolefins results in the final prepared MBBR filler having good mechanical properties, hydrophilicity, biocompatibility, and biofilm formation performance.

[0007] The inventors speculate that the reason why chitosan, maleic anhydride-grafted polyolefin, and anthraquinone compounds containing anhydrides can achieve such good modification effects on polyolefins is that the amino groups on the chitosan macromolecular chain react with the maleic anhydride on the maleic anhydride-grafted polyolefin to form cross-linking products. The cross-linking products and polyolefins together form a semi-interpenetrating polymer network structure. The resulting first filler has good mechanical properties and biocompatibility, and its surface structure is also conducive to bacterial adhesion. Then, anthraquinone compounds containing anhydrides are used to modify the first filler, changing the group composition on the surface of the first filler. At the same time, the semi-interpenetrating polymer network structure is further optimized, which greatly improves the biofilm formation performance of the MBBR filler.

[0008] To improve the hydrophilicity, biocompatibility, and biofilm formation performance of MBBR packing, this invention provides a method for preparing MBBR packing and MBBR packing itself.

[0009] In a first aspect, the method for preparing MBBR packing provided by the present invention adopts the following technical solution:

[0010] A method for preparing MBBR packing material includes the following steps:

[0011] S1. Mix polyolefin, chitosan and maleic anhydride-grafted polyolefin, melt, extrude and mold to obtain the first filler;

[0012] S2. Disperse the first packing material described in step S1 into an organic solvent, add an anthraquinone compound containing an acid anhydride, react, filter, wash, and dry to obtain the MBBR packing material.

[0013] In this invention, polyolefins are commonly used organic polymer materials in the MBBR process and are not particularly limited thereto. In some specific embodiments, the polyolefin can be, but is not limited to, a homopolymer of one of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene, or a copolymer of two or more of them.

[0014] In this invention, the grafting rate of maleic anhydride-grafted polyolefin affects the final semi-interpenetrating polymer network structure. When the grafting rate of maleic anhydride-grafted polyolefin is preferably 0.3% to 2%, the resulting semi-interpenetrating polymer network structure is ideal, and the obtained MBBR filler exhibits good mechanical properties. In some preferred embodiments, the grafting rate of maleic anhydride-grafted polyolefin is specifically 0.3%, 0.5%, 0.8%, 1.0%, 1.3%, 1.5%, 1.8%, 2.0%, or any value between these values.

[0015] In this invention, the maleic anhydride-grafted polyolefin is a maleic anhydride-grafted polyolefin, and is not particularly limited thereto. In some specific embodiments, the maleic anhydride-grafted polyolefin may be, but is not limited to, a homopolymer or a copolymer of two or more of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene.

[0016] In some specific embodiments, the average molecular weight of chitosan is preferably 5,000-100,000, specifically 5,000, 8,000, 10,000, 50,000, 80,000, 100,000 or any value between them; the degree of deacetylation of chitosan is not less than 50%, specifically 50%, 75%, 80%, 90%, infinitely close to 100% or any value between them.

[0017] In this invention, the mass ratio of polyolefin, chitosan, and maleic anhydride-grafted polyolefin in S1 affects the semi-interpenetrating polymer network structure. In some specific embodiments, the mass ratio of polyolefin, chitosan, and maleic anhydride-grafted polyolefin can be 1:(0.05-0.3):(0.1-0.4); more specifically, it can be 1:0.05:0.1, 1:0.05:0.2, 1:0.05:0.4, 1:0.1:0.1, 1:0.1:0.4, 1:0.3:0.2, 1:0.3:0.4, or any value between them. When the mass ratio of olefin, chitosan, and maleic anhydride-grafted polyolefin is preferably 1:(0.1-0.2):(0.1-0.2), the semi-interpenetrating polymer network structure can be further optimized, and the resulting MBBR filler has better mechanical properties.

[0018] In this invention, the organic solvent used in step S2 is a reagent commonly used in the art and is not particularly limited. Specifically, it can be, but is not limited to, benzene, toluene, or a mixture of both. In some specific embodiments, the mass ratio of the first filler to the organic solvent is preferably 1:(5-100), specifically 1:5, 1:10, 1:29, 1:50, 1:100, or any value between them.

[0019] In this invention, the anthraquinone compound containing an anhydride is an anthracene compound having a carbonyl group at C9 and C10 positions, and its molecular structure contains an anhydride. Specifically, it can be, but is not limited to, 1,4-diamino-2,3-dicarboxylic anhydride anthraquinone, anthraquinone-2,3-dicarboxylic anhydride, or a mixture of both. More specifically, the structures of 2,3-anthraquinone anhydride and 1,4-diamino-2,3-dicarboxylic anhydride anthraquinone are shown in formulas (1) and (2), respectively:

[0020]

[0021] In some specific embodiments, the mass ratio of the first filler to the anthraquinone compound containing anhydride in step S2 can be 1:(0.01-0.4), more specifically 1:0.01, 1:0.2, 1:0.3, 1:0.4 or any value between them.

[0022] In this invention, the reaction temperature used in step S2 is such that the unreacted amino group in the first packing material reacts with the anhydride in the anthraquinone compound, typically 60-70°C; the reaction time is adaptively adjusted according to the reaction temperature, typically 1-12 hours.

[0023] In some specific embodiments, the reaction temperature in step S2 is 60°C, 62°C, 64°C, 65°C, 67°C, 68°C, 70°C or any value between them; the reaction time is 1h, 2h, 2.5h, 5h, 8h, 10h, 12h or any value between them.

[0024] Secondly, the MBBR packing provided by this invention adopts the following technical solution:

[0025] An MBBR packing material is prepared by the MBBR packing preparation method described above.

[0026] Beneficial effects:

[0027] In this invention, chitosan and maleic anhydride are used to graft polyolefins to modify the polyolefins, obtaining a first filler. Anthraquinone containing anhydride is then reacted with the first filler. The resulting MBBR filler exhibits good mechanical properties and hydrophilicity, as well as high biofilm formation efficiency. The reason for this is speculated to be that during melting, extrusion, and molding, the amino groups on the chitosan macromolecular chains react with the maleic anhydride grafted onto the polyolefin to form crosslinking products. These crosslinking products can then form a semi-interpenetrating polymer network structure with the polyolefin, resulting in a first filler with good mechanical properties and biocompatibility. Furthermore, the first filler still contains unreacted amino groups, which can undergo ring-opening reactions with the anhydride-containing anhydride. Modifying the first filler with anhydride-containing anhydride results in the MBBR filler containing a certain number of carboxyl groups, altering its surface polarity and improving its surface wettability and hydrophilicity, thus endowing the MBBR filler with excellent biofilm formation performance. Attached Figure Description

[0028] Figure 1 This is one of the result graphs of the biofilm attachment efficiency test in the test examples of this invention;

[0029] Figure 2 This is the second figure showing the results of the biofilm formation efficiency test in the test examples of this invention;

[0030] Figure 3 Figure 3 shows the results of the biofilm formation efficiency test in the test examples of this invention. Detailed Implementation

[0031] The embodiments of the present invention are described in detail below. These embodiments are intended to explain the present invention and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0032] Example 1

[0033] This embodiment illustrates the preparation method of MBBR packing material, which specifically includes:

[0034] S1. Take 100 parts of polyethylene, 20 parts of chitosan and 20 parts of maleic anhydride-grafted polyethylene, mix them evenly, and then melt, extrude, granulate and injection mold them in a twin-screw extruder to obtain the first filler.

[0035] S2. Take 100 parts of the first packing material and mix it evenly with 500 parts of benzene. Then add 40 parts of 2,3-anthracene dicarboxylic anhydride and react at 70°C for 12 hours. Centrifuge to collect the precipitate. Wash the precipitate with acetone, ethanol and deionized water in sequence, and dry it in an oven at 42-45°C for 48 hours to obtain the MBBR packing material.

[0036] In this embodiment, the average molecular weight of polyethylene is 5000, the average molecular weight of chitosan is 15000, and the degree of deacetylation is 75%; the grafting rate of maleic anhydride-grafted polyethylene is 1.5%, and the average molecular weight is 6000.

[0037] Examples 2-6

[0038] Examples 2-6 use the preparation method provided in Example 1 to prepare MBBR fillers, except that in step S1, the mass fractions of polyethylene, chitosan and maleic anhydride-grafted polyethylene are different, as shown in Table 1, while other conditions are the same.

[0039] Table 1.

[0040]

[0041] Example 7

[0042] This embodiment uses the preparation method provided in Example 1 to prepare MBBR filler, with the following differences: In step S1, polypropylene is used instead of polyethylene in equal parts by mass, and the average molecular weight of polypropylene is 5000; the average molecular weight of chitosan is 100000, and the degree of deacetylation is 60%; maleic anhydride-grafted polypropylene is used instead of maleic anhydride-grafted polyethylene in equal parts by mass, and the grafting rate of maleic anhydride-grafted polypropylene is 2%, with an average molecular weight of 6000; other conditions are the same.

[0043] Comparative Example 1

[0044] The comparative example uses the same method as Example 1 to prepare MBBR filler, except that in step S1, an equal mass of polyethylene is used instead of chitosan, while other conditions remain the same.

[0045] Comparative Example 2

[0046] The comparative example uses the same method as Example 1 to prepare MBBR filler, except that in step S1, maleic anhydride-grafted polyethylene is replaced with an equal mass of polyethylene, while other conditions remain the same.

[0047] Examples 8-10

[0048] Examples 8-10 use the preparation method provided in Example 1 to prepare MBBR packing materials. The difference is that the mass fraction of 2,3-anthracene dicarboxylic anhydride, the reaction temperature and time are different in step S2, as shown in Table 2. Other conditions are the same.

[0049] Table 2.

[0050]

[0051] Example 11

[0052] This embodiment uses the preparation method provided in Example 1 to prepare MBBR packing, the difference being that in step S2, 1,4-diamino-2,3-dicarboxylic anhydride anthraquinone is used instead of 2,3-anthraquinone, and other conditions are the same.

[0053] Comparative Example 3

[0054] This comparative example illustrates the preparation method of MBBR filler, which specifically includes: taking 100 parts of polypropylene, 20 parts of chitosan and 20 parts of maleic anhydride-grafted polypropylene, mixing them evenly, and then melting, extruding, granulating and injection molding them in a twin-screw extruder to obtain MBBR filler.

[0055] Test case

[0056] In this test example, the MBBR fillers provided in the above embodiments and comparative examples were injection molded into 10cm×5cm×2mm plates, and their relevant performance was tested according to the following methods:

[0057] (1) Water droplet angle: The water droplet angle was tested using a water droplet angle tester. The water droplet angle was measured at five locations: the four corners and the middle of the plate. The average value was taken and the standard deviation was calculated.

[0058] (2) Tensile strength: Tested in accordance with GB / T 1040-2006.

[0059] (3) Bending strength: Tested in accordance with GB / T 9341-2008.

[0060] (4) Impact strength: Tested in accordance with GB / T 1843-2008.

[0061] (5) Biofilm formation efficiency: Plates were placed in a biofilm reactor for bacterial biofilm formation for 5 days. 1cm × 1cm plates were cut at 1, 2, 3, and 5 days to determine the content of bacterial extracellular polysaccharides on the plate surface. The method for determining the bacterial extracellular polysaccharide content was as follows: PVC packing material with biofilm attached was gently rinsed in sterile water to remove unfixed biomass. Then, a 1cm × 5cm plate was cut and placed in a 10mL test tube. Simultaneously, a 1cm unformed plate was cut as a blank control. 1mL of sterile water was transferred to the test tube, shaken, and then 1mL of 50g / L phenol solution was added. After shaking for 10–20s to mix, 5mL of 95wt% sulfuric acid solution was added, and the reaction was carried out in the dark for 10min. After the reaction, the mixture was shaken for 10s, placed in a test tube, and placed in a 20–30℃ water bath for 10min. The colorimetric determination was performed at 490nm.

[0062] The test results are shown in Table 1 and Figures 1-3 As shown.

[0063] Table 3.

[0064]

[0065] As shown in Table 3, compared with Comparative Examples 1-3, the MBBR packings prepared by the methods provided in Examples 1-11 of this invention have good hydrophilicity and mechanical properties; Figures 1-3 It can be seen that on the third day of biofilm formation, the content of bacterial extracellular polysaccharides on the surface of the MBBR packing material provided in Examples 1-11 of this invention all exceeded 100 μg / cm³. 2 It exhibits rapid biofilm formation, and by day 5 of biofilm formation, the bacterial extracellular polysaccharide content can reach as high as 300 μg / cm³. 2 The good biofilm formation effect indicates that the MBBR packing material provided in Examples 1-11 of this invention has good biocompatibility and biofilm formation performance.

[0066] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for preparing MBBR packing material, characterized in that, The method includes the following steps: S1. Mix polyolefin, chitosan and maleic anhydride-grafted polyolefin, melt, extrude and mold to obtain the first filler; S2. Disperse the first packing material described in step S1 into an organic solvent, add an anthraquinone compound containing an acid anhydride, react, filter, wash, and dry to obtain the MBBR packing material. The anthraquinone compound containing an anhydride is selected from 1,4-diamino-2,3-dicarboxylic anhydride anthraquinone and / or anthraquinone-2,3-dicarboxylic anhydride.

2. The method for preparing MBBR packing according to claim 1, characterized in that, The polyolefin in step S1 is selected as a homopolymer or a copolymer of two or more of the following: ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene.

3. The method for preparing MBBR packing according to claim 1, characterized in that, The chitosan mentioned in step S1 has an average molecular weight of 5,000-100,000 and a degree of deacetylation of not less than 50%.

4. The method for preparing MBBR packing according to claim 1, characterized in that, The maleic anhydride-grafted polyolefin in step S1 is selected from homopolymers of one of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 4-methyl-1-pentene, or copolymers of two or more of them.

5. The method for preparing MBBR packing according to claim 1, characterized in that, The grafting rate of the maleic anhydride-grafted polyolefin in step S1 is 0.3-2%.

6. The method for preparing MBBR packing according to claim 1, characterized in that, The mass ratio of the polyolefin, chitosan, and maleic anhydride-grafted polyolefin in step S1 is 1:(0.05-0.3):(0.1-0.4).

7. The method for preparing MBBR packing according to claim 1, characterized in that, In step S2, the mass ratio of the first filler to the organic solvent is 1:(5-100).

8. The method for preparing MBBR packing according to claim 1, characterized in that, In step S2, the mass ratio of the first filler to the anthraquinone compound containing anhydride is 1:(0.01-0.4).

9. The method for preparing MBBR packing according to claim 1, characterized in that, The reaction temperature in step S2 is 60-70℃, and the reaction time is 1-12h.

10. An MBBR packing material, characterized in that, It is prepared by the method for preparing MBBR packing as described in any one of claims 1 to 9.

Images