Micro-plastic flocculation method based on amyloid protein fibers

Abstract

The invention relates to the technical field of micro-plastic flocculation materials, in particular to a micro-plastic flocculation method based on amyloid protein fibers. In the prior art, a method for realizing micro-plastic flocculation based on soybean protein isolate fibers is not reported. In order to solve the technical problems, the invention provides the micro-plastic flocculation method based on the amyloid protein fiber, which utilizes the unique surface chemical property (especially hydrophobicity) and nanofiber morphology of the amyloid protein fiber to promote adsorption (mainly depending on hydrophobic interaction, assisted by hydrogen bonds, static electricity and the like) through stirring, so that the micro-plastic flocculation effect is improved. And the bridging flocculation effect of the macromolecular long chain is exerted, the dispersed micro-plastic particles are gathered to form a large flocculating constituent easy to settle, and finally, the purification of the micro-plastic polluted water body is realized through gravity settling and solid-liquid separation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microplastic flocculation materials, in particular to a microplastic flocculation method based on amyloid fibers. BACKGROUND

[0002] Microplastics (such as PVC, PC, PET, etc.) as a new pollutant, widely exist in water bodies, due to its small particle size, difficult degradation, easy adsorption of toxic substances and other characteristics, which poses a serious threat to the ecological system and human health. The commonly used microplastic removal technologies such as filtration method, adsorption method and chemical precipitation method have problems such as low efficiency, high cost and secondary pollution.

[0003] Soybean protein isolate as a renewable biological material has rich functional groups (such as amino, carboxyl) and modifiability, but its mechanical strength is poor and its stability is insufficient when used alone. In the prior art, the performance can be improved by cross-linking modification, but there is still a lack of effective scheme for efficient and selective removal of microplastics.

[0004] Therefore, it is of important practical significance to develop a high-efficiency and environmentally-friendly soybean protein isolate-based flocculation material to achieve efficient capture and removal of microplastics. SUMMARY

[0005] The prior art has the problem that there is no report on a method for realizing microplastic flocculation based on soybean protein isolate fibers. In view of the above technical problems, the present application provides a microplastic flocculation method based on amyloid fibers, which comprises the following steps: The amyloid fiber colloid solution is added to the microplastic contaminated water body, and stirring is performed to cause the microplastics in the microplastic contaminated water body to flocculate. After flocculation is completed, the flocculation body is removed by sedimentation separation to obtain a purified water body.

[0006] Preferably, the preparation method of the amyloid fiber colloid solution comprises the following steps: The soybean protein isolate powder is added to ultrapure water, and stirring is performed until the solution is free of particulate matter. Then, hydrochloric acid is added to the solution to adjust the solution to be acidic. Then, stirring and heating are performed to obtain the amyloid fiber colloid solution.

[0007] Preferably, the pH of the hydrochloric acid adjusted solution is 1-5.

[0008] Preferably, the pH of the hydrochloric acid adjusted solution is 2.

[0009] Preferably, the stirring and heating temperature is 90±2℃.

[0010] Preferably, the microplastics include one or more of PVC, PC and PET.

[0011] Preferably, the amyloid fiber colloid solution and the microplastic are used in a ratio of not less than 30 mg:0.1 g.

[0012] The present application has the following advantages: (1) The present application first realizes the flocculation removal of microplastics in microplastic-polluted water bodies by using an amyloid fiber colloid solution prepared based on soybean protein isolate. The soybean protein isolate used in the method is a plant-based biodegradable material, which has the advantages of environmental protection, economy and low cost. (2) The present application utilizes the unique surface chemical properties (especially hydrophobicity) and nanofiber morphology of amyloid fibers. By stirring, adsorption is promoted (mainly relying on hydrophobic interaction, supplemented by hydrogen bonding, electrostatic interaction, etc.), and the bridging flocculation effect of long polymer chains is exerted, so that dispersed microplastic particles are aggregated to form large flocculation bodies that are easy to settle, and finally the purification of microplastic-polluted water bodies is realized through gravity settling and solid-liquid separation. (3) The present application found that the flocculation effect of the amyloid fiber colloid solution formed by heating and stirring at different pH values is significantly different. In acidic conditions (pH=1~5), the flocculation effect of amyloid fibers presents a non-monotonic change, and the flocculation effect at pH=2 is better than that at other pH values. This phenomenon is closely related to the conformational transition of proteins at a specific pH, the distribution of surface charges and the surface properties of microplastics. The possible reasons are as follows: When pH=<2, the strong charge repulsion causes the peptide chain to stretch excessively, forming a rigid disordered structure, and the hydrophobic region is shielded. The strong positive charge causes water molecules to be tightly wrapped (strong hydration layer), which physically blocks the hydrophobic contact with microplastics. The short and fragmented fiber structure can only adsorb single particles, forming small and dense flocs that lack bridging ability. When pH=2, the charge repulsion is weakened, and the peptide chain can be partially folded, exposing the hydrophobic core. The moderate charge makes the hydrophobic region exposed, and it can efficiently combine with microplastics through van der Waals force. The medium-length fiber can wrap multiple microplastic particles at the same time, forming a "net-like flocculation body". When pH=>2, it is close to the isoelectric point (pI≈4.5) of soybean protein. The intermolecular hydrophobic interaction dominates, and it tends to form a dense aggregate. The specific surface area decreases sharply, and the adsorption sites become less. The protein aggregate simply adheres to the microplastic, and tends to generate loose flocs that are easy to break. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 SEM image of amyloid fibers in the amyloid fiber colloid solution obtained in Example 1 of the present application.

[0014] Figure 2 Comparison chart of the flocculation effect of microplastics PVC by the method of Example 1 and Comparative Examples 5 and 6 of the present application.

[0015] Figure 3 : Comparison chart of flocculation effect of microplastic PC by the method of embodiment 1 and comparative examples 5 and 6.

[0016] Figure 4 : Comparison chart of flocculation effect of microplastic PET by the method of embodiment 1 and comparative examples 5 and 6.

[0017] Figure 5 : Comparison chart of flocculation effect of microplastic PVC by the method of embodiment 1 and comparative examples 1-4 under different pH conditions.

[0018] Figure 6 : Comparison chart of flocculation effect of microplastic PC by the method of embodiment 1 and comparative examples 1-4 under different pH conditions.

[0019] Figure 7 : Comparison chart of flocculation effect of microplastic PET by the method of embodiment 1 and comparative examples 1-4 under different pH conditions. DETAILED DESCRIPTION

[0020] The application will be described in detail below with reference to the embodiments. It should be understood that the following embodiments are only examples of the embodiments of the application, and are not a limitation on the scope of the application.

[0021] Embodiment 1

[0022] 10 g of soybean protein isolate powder was added to 480 mL of ultrapure water, and stirred until there were no particulate matters in the solution. Then, 1 mol / L hydrochloric acid was added to the solution to adjust the pH to 2, and then heated and stirred at 90°C for 8 h to obtain a amyloid fibril colloidal solution.

[0023] (a) 0.1 g of PVC was added to 1000 mL of deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L. 30 mL of the amyloid fibril colloidal solution was added to the PVC aqueous solution, and stirred at 400 rpm for 10 min. After standing for 10 min, the flocculation body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by drying and weighing method. The specific test results are shown in Table 1 and Table 1-continued.

[0024] (b) 0.1 g of PET was added to 1000 mL of deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L. 30 mL of the amyloid fibril colloidal solution was added to the PVC aqueous solution, and stirred at 400 rpm for 10 min. After standing for 10 min, the flocculation body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by drying and weighing method. The specific test results are shown in Table 1 and Table 1-continued.

[0025] (c) 0.1 g PC was added into 1000 mL deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L, 30 mL amyloid fibril colloidal solution was added into the PVC aqueous solution, after stirring at 400 rpm for 10 min, standing for 10 min, the flocculation body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by the drying and weighing method. The specific test results are shown in Table 1, Table 1.

[0026] Comparative Example 1

[0027] 10 g soybean protein isolate powder was added into 480 mL ultrapure water, and stirred until there were no particulate matters in the solution. Then, 1 mol / L hydrochloric acid was added into the solution to adjust the pH value of the solution to 1. After that, the solution was heated and stirred at 90 °C for 8 h to obtain an amyloid fibril colloidal solution.

[0028] (a) 0.1 g PVC was added into 1000 mL deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L, 30 mL amyloid fibril colloidal solution was added into the PVC aqueous solution, after stirring at 400 rpm for 10 min, standing for 10 min, the flocculation body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by the drying and weighing method. The specific test results are shown in Table 2.

[0029] (b) 0.1 g PET was added into 1000 mL deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L, 30 mL amyloid fibril colloidal solution was added into the PVC aqueous solution, after stirring at 400 rpm for 10 min, standing for 10 min, the flocculation body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by the drying and weighing method. The specific test results are shown in Table 2.

[0030] (c) 0.1 g PC was added into 1000 mL deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L, 30 mL amyloid fibril colloidal solution was added into the PVC aqueous solution, after stirring at 400 rpm for 10 min, standing for 10 min, the flocculation body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by the drying and weighing method. The specific test results are shown in Table 2.

[0031] Comparative Example 2

[0032] 10g soybean protein isolate powder was added to 480mL ultrapure water, stirred until there were no particles in the solution, then 1mol / L hydrochloric acid was added to the solution to adjust the solution pH=3, then heated and stirred at 90℃ for 8h to obtain amyloid fibril colloidal solution.

[0033] (a) 0.1g PVC was added to 1000mL deionized water to obtain a PVC aqueous solution with a concentration of 0.1g / L, 30mL amyloid fibril colloidal solution was added to the PVC aqueous solution, stirred at 400rpm for 10min, then placed for 10min, then the flocculation body was separated by vacuum filtration to obtain clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by drying and weighing method. The specific test results are shown in Table 3.

[0034] (b) 0.1g PET was added to 1000mL deionized water to obtain a PVC aqueous solution with a concentration of 0.1g / L, 30mL amyloid fibril colloidal solution was added to the PVC aqueous solution, stirred at 400rpm for 10min, then placed for 10min, then the flocculation body was separated by vacuum filtration to obtain clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by drying and weighing method. The specific test results are shown in Table 3.

[0035] (c) 0.1g PC was added to 1000mL deionized water to obtain a PVC aqueous solution with a concentration of 0.1g / L, 30mL amyloid fibril colloidal solution was added to the PVC aqueous solution, stirred at 400rpm for 10min, then placed for 10min, then the flocculation body was separated by vacuum filtration to obtain clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by drying and weighing method. The specific test results are shown in Table 3.

[0036] Comparative Example 3

[0037] 10g soybean protein isolate powder was added to 480mL ultrapure water, stirred until there were no particles in the solution, then 1mol / L hydrochloric acid was added to the solution to adjust the solution pH=4, then heated and stirred at 90℃ for 8h to obtain amyloid fibril colloidal solution.

[0038] (a) 0.1g PVC was added to 1000mL deionized water to obtain a PVC aqueous solution with a concentration of 0.1g / L, 30mL amyloid fibril colloidal solution was added to the PVC aqueous solution, stirred at 400rpm for 10min, then placed for 10min, then the flocculation body was separated by vacuum filtration to obtain clean water body. The flocculation efficiency of the amyloid fibril colloidal solution was tested by drying and weighing method. The specific test results are shown in Table 4.

[0039] (b) 0.1 g of PET was added to 1000 mL of deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L, 30 mL of amyloid fiber colloidal solution was added to the PVC aqueous solution, stirred at 400 rpm for 10 min, and then left to stand for 10 min. The flocculated body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fiber colloidal solution was tested by the drying and weighing method. The specific test results are shown in Table 4.

[0040] (c) 0.1 g of PC was added to 1000 mL of deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L, 30 mL of amyloid fiber colloidal solution was added to the PVC aqueous solution, stirred at 400 rpm for 10 min, and then left to stand for 10 min. The flocculated body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fiber colloidal solution was tested by the drying and weighing method. The specific test results are shown in Table 4.

[0041] Comparative Example 4

[0042] 10 g of soybean protein isolate powder was added to 480 mL of ultrapure water and stirred until there were no particulate matters in the solution. Then, 1 mol / L hydrochloric acid was added to adjust the pH of the solution to 5, and then the solution was heated and stirred at 90°C for 8 h to obtain an amyloid fiber colloidal solution.

[0043] (a) 0.1 g of PVC was added to 1000 mL of deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L, 30 mL of amyloid fiber colloidal solution was added to the PVC aqueous solution, stirred at 400 rpm for 10 min, and then left to stand for 10 min. The flocculated body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fiber colloidal solution was tested by the drying and weighing method. The specific test results are shown in Table 5.

[0044] (b) 0.1 g of PET was added to 1000 mL of deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L, 30 mL of amyloid fiber colloidal solution was added to the PVC aqueous solution, stirred at 400 rpm for 10 min, and then left to stand for 10 min. The flocculated body was separated by vacuum filtration to obtain a clean water body. The flocculation efficiency of the amyloid fiber colloidal solution was tested by the drying and weighing method. The specific test results are shown in Table 5.

[0045] (c) 0.1 g PC was added into 1000 mL deionized water to obtain a PVC aqueous solution with a concentration of 0.1 g / L, 30 mL of the amyloid fiber colloidal solution was added into the PVC aqueous solution, and after stirring at 400 rpm for 10 min, standing for 10 min, and separating the flocculation body by vacuum filtration, a clean water body was obtained. The flocculation efficiency of the amyloid fiber colloidal solution was tested by a drying and weighing method. The specific test results are shown in Table 5.

[0046] The SEM image of the amyloid fiber in the amyloid fiber colloidal solution obtained in Example 1 of the present application is shown in the accompanying drawings of the specification. Figure 1

[0047] The comparison chart of the flocculation effect of microplastic PVC by the method of Example 1 and Comparative Examples 5 and 6 is shown in the accompanying drawings of the specification. Figure 2

[0048] The comparison chart of the flocculation effect of microplastic PC by the method of Example 1 and Comparative Examples 5 and 6 is shown in the accompanying drawings of the specification. Figure 3

[0049] The comparison chart of the flocculation effect of microplastic PET by the method of Example 1 and Comparative Examples 5 and 6 is shown in the accompanying drawings of the specification. Figure 4

[0050] The comparison chart of the flocculation effect of microplastic PVC by the method of Example 1 and Comparative Examples 1-4 under different pH conditions is shown in the accompanying drawings of the specification. Figure 5

[0051] The comparison chart of the flocculation effect of microplastic PC by the method of Example 1 and Comparative Examples 1-4 under different pH conditions is shown in the accompanying drawings of the specification. Figure 6

[0052] The comparison chart of the flocculation effect of microplastic PET by the method of Example 1 and Comparative Examples 1-4 under different pH conditions is shown in the accompanying drawings of the specification. Figure 7

[0053] Table 1

[0054] Continued Table 1

[0055] Table 2

[0056] Table 3

[0057] Table 4 ​​​​​​​

[0058] Table 5

[0059] Comparative Example 5 is the same as Example 1 except that Comparative Example 5 uses a PAC (polyaluminum chloride, inorganic polymer flocculant) aqueous solution instead of the amyloid fibril colloid solution in Example 1. The PAC aqueous solution is a uniform solution formed by adding 10 g of PAC into 480 mL of ultrapure water. The flocculation efficiency of the PAC aqueous solution is tested by the dry-weighing method. The specific test results are shown in Table 6.

[0060] Table 6

[0061] Comparative Example 6 is the same as Example 1 except that Comparative Example 5 uses a soybean protein isolate solution instead of the amyloid fibril colloid solution in Example 1. The soybean protein isolate solution is a uniform solution formed by dissolving 10 g of soybean protein isolate into 480 mL of ultrapure water. The flocculation efficiency of the soybean protein isolate solution is tested by the dry-weighing method. The specific test results are shown in Table 7.

[0062] Table 7

[0063] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A method for microplastic flocculation based on amyloid protein fibers, characterized in that, The steps are as follows: Amyloid cellulose colloidal solution is added to water contaminated with microplastics and stirred to cause the microplastics in the water to flocculate. After flocculation, the flocs are removed by sedimentation separation to obtain purified water.

2. The microplastic flocculation method based on amyloid protein fibers according to claim 1, characterized in that, The preparation method of amyloid fibrous colloidal solution includes the following steps: Soy protein isolate powder was added to ultrapure water and stirred until the solution was free of particles. Then, hydrochloric acid was added to adjust the solution to be acidic. After stirring and heating, an amyloid fibrous colloidal solution was obtained.

3. The microplastic flocculation method based on amyloid protein fibers according to claim 2, characterized in that, Adjust the pH of the solution to 1-5 with hydrochloric acid.

4. The microplastic flocculation method based on amyloid protein fibers according to claim 3, characterized in that, The pH of the solution was adjusted to 2 using hydrochloric acid.

5. The microplastic flocculation method based on amyloid protein fibers according to claim 2, characterized in that, The stirring and heating temperature is 90±2℃.

6. The microplastic flocculation method based on amyloid protein fibers according to claim 1, characterized in that, Microplastics include one or more of PVC, PC, and PET.

7. The microplastic flocculation method based on amyloid protein fibers according to claim 1, characterized in that, The ratio of amyloid fibrous colloidal solution to microplastics should be no less than 30 mg: 0.1 g.

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