CN117946515A - Photocatalytic degradable starch-based micro plastic and preparation method thereof - Google Patents
Photocatalytic degradable starch-based micro plastic and preparation method thereof Download PDFInfo
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- 229920002472 Starch Polymers 0.000 title claims abstract description 46
- 239000008107 starch Substances 0.000 title claims abstract description 46
- 235000019698 starch Nutrition 0.000 title claims abstract description 46
- 229920000426 Microplastic Polymers 0.000 title claims abstract description 41
- 230000001699 photocatalysis Effects 0.000 title claims abstract description 33
- 238000002360 preparation method Methods 0.000 title abstract description 9
- 229910010413 TiO 2 Inorganic materials 0.000 claims abstract description 78
- 229920000881 Modified starch Polymers 0.000 claims abstract description 26
- 239000004368 Modified starch Substances 0.000 claims abstract description 26
- 235000019426 modified starch Nutrition 0.000 claims abstract description 26
- 239000011941 photocatalyst Substances 0.000 claims abstract description 23
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 22
- 229920005989 resin Polymers 0.000 claims abstract description 15
- 239000011347 resin Substances 0.000 claims abstract description 15
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 11
- 239000002994 raw material Substances 0.000 claims abstract description 8
- 239000006087 Silane Coupling Agent Substances 0.000 claims abstract description 5
- 239000000314 lubricant Substances 0.000 claims abstract description 5
- 239000004014 plasticizer Substances 0.000 claims abstract description 5
- 238000003756 stirring Methods 0.000 claims description 75
- 238000002156 mixing Methods 0.000 claims description 50
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 43
- 239000008367 deionised water Substances 0.000 claims description 33
- 229910021641 deionized water Inorganic materials 0.000 claims description 33
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 30
- 239000011259 mixed solution Substances 0.000 claims description 29
- 238000006243 chemical reaction Methods 0.000 claims description 27
- 238000010438 heat treatment Methods 0.000 claims description 23
- 238000001035 drying Methods 0.000 claims description 21
- 238000000227 grinding Methods 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 20
- 239000000843 powder Substances 0.000 claims description 20
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 19
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 18
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 claims description 18
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 claims description 17
- -1 bis- (4-hydroxybenzoyl) -amine Chemical compound 0.000 claims description 17
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 15
- UKLDJPRMSDWDSL-UHFFFAOYSA-L [dibutyl(dodecanoyloxy)stannyl] dodecanoate Chemical compound CCCCCCCCCCCC(=O)O[Sn](CCCC)(CCCC)OC(=O)CCCCCCCCCCC UKLDJPRMSDWDSL-UHFFFAOYSA-L 0.000 claims description 15
- 239000012975 dibutyltin dilaurate Substances 0.000 claims description 15
- 229910052757 nitrogen Inorganic materials 0.000 claims description 15
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 14
- 229920001730 Moisture cure polyurethane Polymers 0.000 claims description 14
- 229920003023 plastic Polymers 0.000 claims description 12
- 239000004033 plastic Substances 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 10
- 239000000725 suspension Substances 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 229960005070 ascorbic acid Drugs 0.000 claims description 9
- 235000010323 ascorbic acid Nutrition 0.000 claims description 9
- 239000011668 ascorbic acid Substances 0.000 claims description 9
- 229920000515 polycarbonate Polymers 0.000 claims description 9
- 239000004417 polycarbonate Substances 0.000 claims description 9
- 239000005058 Isophorone diisocyanate Substances 0.000 claims description 7
- 229960000583 acetic acid Drugs 0.000 claims description 7
- YHWCPXVTRSHPNY-UHFFFAOYSA-N butan-1-olate;titanium(4+) Chemical compound [Ti+4].CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-] YHWCPXVTRSHPNY-UHFFFAOYSA-N 0.000 claims description 7
- 239000012362 glacial acetic acid Substances 0.000 claims description 7
- NIMLQBUJDJZYEJ-UHFFFAOYSA-N isophorone diisocyanate Chemical compound CC1(C)CC(N=C=O)CC(C)(CN=C=O)C1 NIMLQBUJDJZYEJ-UHFFFAOYSA-N 0.000 claims description 7
- SZEMGTQCPRNXEG-UHFFFAOYSA-M trimethyl(octadecyl)azanium;bromide Chemical compound [Br-].CCCCCCCCCCCCCCCCCC[N+](C)(C)C SZEMGTQCPRNXEG-UHFFFAOYSA-M 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 6
- 229920002565 Polyethylene Glycol 400 Polymers 0.000 claims description 5
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 5
- 230000032683 aging Effects 0.000 claims description 5
- 238000000498 ball milling Methods 0.000 claims description 5
- 239000004202 carbamide Substances 0.000 claims description 5
- 239000000919 ceramic Substances 0.000 claims description 5
- QGBSISYHAICWAH-UHFFFAOYSA-N dicyandiamide Chemical compound NC(N)=NC#N QGBSISYHAICWAH-UHFFFAOYSA-N 0.000 claims description 5
- 235000019441 ethanol Nutrition 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- 238000000967 suction filtration Methods 0.000 claims description 5
- 238000009210 therapy by ultrasound Methods 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- 238000005303 weighing Methods 0.000 claims description 5
- 150000002009 diols Chemical class 0.000 claims description 4
- 239000000243 solution Substances 0.000 claims description 4
- 239000011159 matrix material Substances 0.000 abstract description 16
- 239000000463 material Substances 0.000 abstract description 13
- 238000013033 photocatalytic degradation reaction Methods 0.000 abstract description 5
- 230000004048 modification Effects 0.000 abstract description 4
- 238000012986 modification Methods 0.000 abstract description 4
- 239000012779 reinforcing material Substances 0.000 abstract description 2
- 229920002635 polyurethane Polymers 0.000 description 9
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- 238000006731 degradation reaction Methods 0.000 description 8
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- 235000019387 fatty acid methyl ester Nutrition 0.000 description 6
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- 239000001301 oxygen Substances 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 238000007146 photocatalysis Methods 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 125000004432 carbon atom Chemical group C* 0.000 description 4
- 238000004132 cross linking Methods 0.000 description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 239000002135 nanosheet Substances 0.000 description 4
- 229920000728 polyester Polymers 0.000 description 4
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 4
- 239000002356 single layer Substances 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 238000005215 recombination Methods 0.000 description 3
- 230000006798 recombination Effects 0.000 description 3
- 239000004970 Chain extender Substances 0.000 description 2
- 239000002841 Lewis acid Substances 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 150000003949 imides Chemical class 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 238000001746 injection moulding Methods 0.000 description 2
- 150000007517 lewis acids Chemical class 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
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- 238000001179 sorption measurement Methods 0.000 description 2
- 150000005846 sugar alcohols Polymers 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229920006238 degradable plastic Polymers 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L75/00—Compositions of polyureas or polyurethanes; Compositions of derivatives of such polymers
- C08L75/04—Polyurethanes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/24—Nitrogen compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/24—Acids; Salts thereof
- C08K3/26—Carbonates; Bicarbonates
- C08K2003/265—Calcium, strontium or barium carbonate
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2201/00—Properties
- C08L2201/06—Biodegradable
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
The invention discloses a photocatalytic degradable starch-based micro plastic and a preparation method thereof. The micro plastic comprises the following raw materials in parts by weight: 40-50 parts of modified starch, 8-12 parts of PVC resin, 0.1-0.3 part of silane coupling agent, 3-5 parts of calcium carbonate, 0.5-2 parts of photocatalyst, 0.5-1 part of plasticizer and 0.3-0.8 part of lubricant. The micro plastic provided by the invention takes the starch as a base material, and is subjected to modification treatment, so that the mechanical property of the matrix is improved; PVC resin is also used as a reinforcing material to be introduced into the matrix, so that the comprehensive performance of the microplastic is improved; in addition, a modified TiO 2 photocatalyst is also introduced, so that the material has excellent photocatalytic degradation capability under visible light.
Description
Technical Field
The invention relates to the technical field of starch-based microplastic, in particular to a photocatalytic degradable starch-based microplastic and a preparation method thereof.
Background
The micro plastic as a novel material has the characteristics of miniaturization, high efficiency and multifunction, is widely applied to the fields of medicine, environmental protection, automobiles, electronics, aerospace and the like, and brings more convenience to the life of people. However, these microplastic materials are discharged into the environment, which may cause serious pollution to the environment. Although microplastic can degrade in nature, this degradation process is very slow, and therefore, it needs to be treated to degrade it rapidly, thereby reducing the harm to the environment. Among the numerous degradable plastics, starch-based plastics have the advantages of wide sources, no toxicity, no harm, good compatibility with other materials, and the like, but the starch-based plastics have the defects of poor mechanical properties, poor heat resistance, and the like, and the comprehensive performance of the plastics can be improved by blending the starch-based plastics with other resin materials. The blended material is generally only biodegradable based on starch base during degradation, but the biodegradable mode has certain limitation after the materials such as PVC resin, polyurethane and the like are added. Thus, photocatalytic degradation can be employed for such materials to increase the degradability of the plastic.
However, tiO 2, which is one of the common materials in photocatalytic degradation of plastics, has excellent chemical stability, thermal stability, super hydrophilicity, etc., but still has many drawbacks, which limit the reagent application of the TiO 2 photocatalyst, for example: 1) The light response range of TiO 2 is narrow, the band is forbidden, only ultraviolet light can be absorbed, but the ultraviolet light on the surface of the earth is less than 5%; 2) The recombination rate of photo-generated electron-hole pairs is high, and the catalytic efficiency is greatly reduced. Therefore, researchers need to modify TiO 2 as a photocatalyst to develop an efficient photocatalytic degradable starch-based microplastic to meet the needs of people.
Disclosure of Invention
In order to solve the technical problems, the invention provides a photocatalytic degradable starch-based micro plastic and a preparation method thereof.
The aim of the invention can be achieved by the following technical scheme:
a photocatalytic degradable starch-based micro plastic comprises the following raw materials in parts by weight: 40-50 parts of modified starch, 8-12 parts of PVC resin, 0.1-0.3 part of silane coupling agent, 3-5 parts of calcium carbonate, 0.5-2 parts of photocatalyst, 0.5-1 part of plasticizer and 0.3-0.8 part of lubricant;
The photocatalyst is Ce/TiO 2@SiQDs-g-C3N4;
specifically, ce/TiO 2@SiQDs-g-C3N4 is prepared by the steps of:
step A1: adding tetrabutyl titanate into a beaker containing absolute ethyl alcohol, mixing and stirring for 30min to obtain a mixed solution 1, stirring deionized water, glacial acetic acid and absolute ethyl alcohol in the beaker uniformly, adding PEG-400 and cerium nitrate, mixing and stirring for 30min to obtain a mixed solution 2, slowly dripping the mixed solution 2 into the mixed solution 1 by using a dropping funnel, continuously stirring for 1-2h, standing and aging for 48h, drying the mixture at a constant temperature of 80 ℃ for 6h, grinding, and roasting in a muffle furnace at 550 ℃ for 2h to obtain Ce/TiO 2;
In the step A1, cerium nitrate is used as a Ce source, a sol-gel method is used for preparing Ce-doped TiO 2, so that the photocatalysis performance of TiO 2 is improved, because the radius of Ce ions is 0.102nm and is far greater than Ti 4+, solid Ce ions cannot enter a TiO 2 matrix, rare earth ions are strong Lewis acid, non-bridging oxygen ions on the surface of TiO 2 are easily combined to form rare earth oxide, ti 4+ can replace Ce ions in the rare earth oxide, and the reduced Ti 3+ and oxygen defects are favorable for separating photo-generated electron-hole pairs, so that the photocatalysis performance is improved;
Further, the dosage ratio of tetrabutyl titanate to absolute ethyl alcohol in the mixed solution 1 is 5-10mL:10-20mL; the dosage ratio of deionized water, glacial acetic acid, absolute ethyl alcohol, PEG-400 and cerium nitrate in the mixed solution 2 is 3.4-6.8mL:5-10mL:5-10mL:1-2mL:0.005-0.015g.
Step A2: adding ascorbic acid into deionized water, stirring and mixing uniformly, introducing nitrogen into the mixed solution for 20min, adding Ce/TiO 2 and 3-aminopropyl triethoxysilane water solution, stirring for 20min, transferring to an autoclave, placing in a baking oven at 170-200 ℃ for reaction for 24h, cooling to room temperature after the reaction is finished, dialyzing for 2 days, centrifuging, washing to neutrality, and drying at 60 ℃ for 12h to obtain Ce/TiO 2 @ SiQDs;
In the step A2, ascorbic acid is used as a reducing agent, silicon quantum dots are generated on the surface of Ce/TiO 2 in situ to realize the coating of the Ce/TiO 2 by the silicon quantum dots, the band gap width of the composite material is reduced, the generation of photo-generated electron-hole pairs is facilitated, the photo-generated holes have enough positive potential to generate OH free radicals with water molecules and hydroxyl groups adsorbed on the surface of the silicon quantum dots, the OH free radicals can attack PVC molecular chains and starch molecular chains in a matrix to generate free radical short chain molecules with carbon atoms as centers, and the short chain molecules can be degraded and converted into CO 2 and H 2 O after light irradiation;
Further, the dosage ratio of the ascorbic acid, the deionized water, the Ce/TiO 2 and the 3-aminopropyl triethoxysilane is 0.8-1.2g:16-24mL:0.5-1.5g:50mL of an aqueous solution of 3-aminopropyl triethoxysilane was prepared from 3-aminopropyl triethoxysilane and deionized water in an amount of 10-16mL:34-40mL of the mixture is mixed and stirred.
Step A3: dispersing Ce/TiO 2 @ SiQDs in deionized water, stirring and mixing uniformly, adding octadecyl trimethyl ammonium bromide, heating to 60-70 ℃, stirring and reacting for 3-5 hours, and after the reaction is finished, carrying out suction filtration and drying to obtain pretreated Ce/TiO 2 @ SiQDs;
Further, the dosage ratio of Ce/TiO 2 @ SiQDs, deionized water and octadecyl trimethyl ammonium bromide is 2-4g:20mL:0.03-0.05g.
Step A4: urea and dicyandiamide were mixed in a ratio of 7:3, ball milling for 1-2h at a rotating speed of 400rpm, grinding 5g of ball milled powder, putting the powder into a ceramic crucible, heating for 4h at 550 ℃, grinding the product into powder, transferring the powder into a muffle furnace, heating to 520 ℃, preserving heat for 2h, collecting g-C 3N4, dispersing g-C 3N4 into deionized water, stirring and mixing uniformly, adding pretreatment Ce/TiO 2 @ SiQDs, stirring and mixing to obtain suspension, performing ultrasonic treatment on the suspension for 30min, stirring for 2-3h at a rotating speed of 500rpm, filtering and drying after the reaction is finished, and finally heating the product for 2h at 500 ℃ to obtain Ce/TiO 2@SiQDs-g-C3N4;
In the step A4, a thermal oxidation etching method is adopted to strip the large-scale g-C 3N4 to obtain a single-layer or less-layer negatively charged g-C 3N4 nano-sheet, then electrostatic adsorption is utilized to tightly combine the single-layer or less-layer negatively charged g-C 3N4 nano-sheet with pretreatment Ce/TiO 2 @ SiQDs to prepare Ce/TiO 2@SiQDs-g-C3N4 (photocatalyst), electrons on a guide belt can be quickly transferred to the g-C 3N4 in the photocatalysis process and react with oxygen to form superoxide radicals (O 2 -),·O2 - can also attack PVC molecular chains in a matrix to generate radical short-chain molecules taking carbon atoms as centers, thereby improving the photocatalysis degradation capability of PVC molecules, and in addition, g-C 3N4 is taken as an electron acceptor to effectively reduce the recombination rate of photo-generated electron-hole pairs in TiO 2, thereby enhancing the catalysis degradation capability of the photocatalyst.
Further, the dosage ratio of g-C 3N4, deionized water and pretreatment Ce/TiO 2 @ SiQDs is 1-2g:20mL:1.2-2.2g.
The modified starch is prepared by the following steps:
Step B1: adding polycarbonate dihydric alcohol (M n = 2000), isophorone diisocyanate and N, N-dimethylformamide into a reactor, stirring and mixing uniformly, then adding 2/3 of dibutyltin dilaurate, stirring and reacting for 1-2h under the conditions of nitrogen and 75 ℃, adding bis- (4-hydroxybenzoyl) -amine and the rest 1/3 of dibutyltin dilaurate, stirring and reacting for 30min, and then placing the mixture at 80 ℃ and rotating for 2h under reduced pressure to obtain an end-NCO polyurethane prepolymer;
Further, the polycarbonate diol, isophorone diisocyanate, N-dimethylformamide, dibutyltin dilaurate and bis- (4-hydroxybenzoyl) -amine are used in an amount ratio of 0.2 to 0.6g:0.02-0.03g:10mL:0.01-0.03mL:0.03-0.05g.
Step B2: adding starch and terminal-NCO polyurethane prepolymer into a high-speed stirrer, stirring for 10min at 600rpm, heating to 80-90 ℃ under nitrogen, and reducing the rotation speed to 150rpm for continuous reaction for 1-2h to obtain modified starch;
Further, the dosage ratio of starch to terminal-NCO polyurethane prepolymer is 10-20g:8-12g.
In the modified starch, firstly, polycarbonate diol is used as polyalcohol to synthesize polyester polyurethane, and a large number of polar groups are contained in the polyester polyurethane, so that the modified starch has a more compact and stable structure, water molecules are difficult to penetrate, the water resistance of a matrix is improved, and the durability of the matrix is further improved; secondly, bis- (4-hydroxybenzoyl) -amine with heat-resistant group imide is used as a chain extender to be introduced into polyurethane, so that the heat resistance of the polyurethane is improved; and finally, the terminal-NCO groups in the terminal-NCO polyurethane prepolymer and the hydroxyl groups in the starch molecules are utilized to carry out crosslinking reaction to form a crosslinked network structure, so that the crosslinking density of the starch molecules is increased, and the mechanical properties of the matrix are further improved.
The preparation method of the photocatalytic degradable starch-based micro plastic comprises the following steps:
Step S1: weighing raw materials according to parts by weight, adding modified starch, PVC resin, calcium carbonate and a silane coupling agent into a mixer, and mixing for 10-20min at 110-130 ℃ to obtain a premix;
Step S2: adding a photocatalyst, a plasticizer and a lubricant into the premix, mixing for 20min, cooling the mixture to 35-45 ℃, standing for 48h at room temperature, granulating in a screw granulator, and grinding and crushing the plastic particles in a grinder to obtain the photocatalytic degradable starch-based micro plastic.
The invention has the beneficial effects that:
The micro plastic provided by the invention takes the starch as a base material, and is subjected to modification treatment, so that the mechanical property of the matrix is improved; PVC resin is also used as a reinforcing material to be introduced into the matrix, so that the comprehensive performance of the microplastic is improved; in addition, a modified TiO 2 photocatalyst is also introduced, so that the material has excellent photocatalytic degradation capability under visible light.
In the photocatalyst, tiO 2 is used as a photocatalytic material and is subjected to modification treatment, 1) cerium nitrate is used as a Ce source, and Ce-doped TiO 2 is prepared by a sol-gel method, so that the photocatalytic performance of TiO 2 is improved, the radius of Ce ions is 0.102nm and is far greater than that of Ti 4+, solid Ce ions cannot enter a TiO 2 matrix, rare earth ions are strong Lewis acid and are easy to combine with non-bridging oxygen ions on the surface of TiO 2 to form rare earth oxide, ti 4+ replaces Ce ions in the rare earth oxide, and the reduced Ti 3+ and oxygen defects are favorable for separation of photogenerated electron-hole pairs, so that the photocatalytic performance is improved; 2) The ascorbic acid is used as a reducing agent, silicon quantum dots are generated on the surface of Ce/TiO 2 in situ to realize the coating of the Ce/TiO 2 by the silicon quantum dots, the band gap width of the composite material is reduced, the generation of photo-generated electron-hole pairs is facilitated, the photo-generated holes have enough positive potential to generate OH free radicals with water molecules and hydroxyl groups adsorbed on the surface of the silicon quantum dots, the OH free radicals can attack PVC molecular chains and starch molecular chains in a matrix to generate free radical short chain molecules taking carbon atoms as centers, and the short chain molecules can be degraded and converted into CO 2 and H 2 O after being irradiated by light; 3) The method comprises the steps of stripping a large block of g-C 3N4 by adopting a thermal oxidation etching method to obtain a single-layer or less-layer negatively charged g-C 3N4 nano sheet, then tightly combining the single-layer or less-layer negatively charged g-C 3N4 nano sheet with positively charged pretreatment Ce/TiO 2 @ SiQDs by utilizing electrostatic adsorption to prepare Ce/TiO 2@SiQDs-g-C3N4 (photocatalyst), rapidly transferring electrons on a guide belt to g-C 3N4 in the photocatalysis process, and reacting with oxygen to form superoxide radicals (O 2 -),·O2 - can attack PVC molecular chains in a matrix to generate radical molecules taking carbon atoms as centers, so that the photocatalytic degradation capability of the PVC molecules is improved; in addition, g-C 3N4 is used as an electron acceptor, and can also effectively reduce the recombination rate of photo-generated electron-hole pairs in TiO 2, so that the catalytic degradation capability of the photocatalyst is enhanced.
In the modified starch, firstly, polycarbonate diol is used as polyalcohol to synthesize polyester polyurethane, and a large number of polar groups are contained in the polyester polyurethane, so that the modified starch has a more compact and stable structure, water molecules are difficult to penetrate, the water resistance of a matrix is improved, and the durability of the matrix is further improved; secondly, bis- (4-hydroxybenzoyl) -amine with heat-resistant group imide is used as a chain extender to be introduced into polyurethane, so that the heat resistance of the polyurethane is improved; and finally, the terminal-NCO groups in the terminal-NCO polyurethane prepolymer and the hydroxyl groups in the starch molecules are utilized to carry out crosslinking reaction to form a crosslinked network structure, so that the crosslinking density of the starch molecules is increased, and the mechanical properties of the matrix are further improved.
Detailed Description
The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
1) Ce/TiO 2@SiQDs-g-C3N4 is prepared by the steps of:
Step A1: adding 5mL of tetrabutyl titanate into a beaker containing 10mL of absolute ethyl alcohol, mixing and stirring for 30min, marking as a mixed solution 1, uniformly stirring and mixing 3.4mL of deionized water, 5mL of glacial acetic acid and 5mL of absolute ethyl alcohol in the beaker, adding 1mL of PEG-400 and 0.005g of cerium nitrate, mixing and stirring for 30min, marking as a mixed solution 2, slowly dripping the mixed solution 2 into the mixed solution 1 by using a dropping funnel, continuously stirring for 1h, standing and ageing for 48h, drying the mixture at a constant temperature of 80 ℃ for 6h, grinding, and roasting in a muffle furnace at 550 ℃ for 2h to obtain Ce/TiO 2;
Step A2: adding 0.8g of ascorbic acid into 16mL of deionized water, stirring and mixing uniformly, introducing nitrogen into the mixed solution for 20min, adding 0.5g of Ce/TiO 2 and 50mL of 3-aminopropyl triethoxysilane aqueous solution, continuously stirring for 20min, transferring into an autoclave, placing into a 170 ℃ oven for reaction for 24h, cooling to room temperature after the reaction is finished, dialyzing for 2 days, centrifuging, washing to neutrality, and drying at 60 ℃ for 12h to obtain the Ce/TiO 2 @ SiQDs, wherein the 3-aminopropyl triethoxysilane aqueous solution is prepared from 3-aminopropyl triethoxysilane and deionized water in a ratio of 10mL: mixing and stirring 40mL of the mixture;
Step A3: dispersing 2g of Ce/TiO 2 @ SiQDs in 20mL of deionized water, stirring and mixing uniformly, adding 0.03g of octadecyl trimethyl ammonium bromide, heating to 60 ℃, stirring and reacting for 3 hours, and after the reaction is finished, carrying out suction filtration and drying to obtain pretreated Ce/TiO 2 @ SiQDs;
Step A4: urea and dicyandiamide were mixed in a ratio of 7:3, ball milling for 1h at a rotating speed of 400rpm, grinding 5g of ball milled powder, putting the powder into a ceramic crucible, heating for 4h at 550 ℃, grinding the product into powder, transferring the powder into a muffle furnace, heating to 520 ℃, preserving heat for 2h, collecting g-C 3N4, dispersing 1g g-C 3N4 into 20mL of deionized water, stirring and mixing uniformly, adding 1.2g of pretreatment Ce/TiO 2 @ SiQDs, stirring and mixing to obtain a suspension, performing ultrasonic treatment on the suspension for 30min, stirring for 2h at a rotating speed of 500rpm, filtering and drying after the reaction is finished, and finally heating the product at 500 ℃ for 2h to obtain Ce/TiO 2@SiQDs-g-C3N4.
2) The modified starch is prepared by the following steps:
Step B1: adding 0.4g of polycarbonate dihydric alcohol (M n =2000), 0.025g of isophorone diisocyanate and 10mL of N, N-dimethylformamide into a reactor, stirring and mixing uniformly, then adding 2/3 of dibutyltin dilaurate, stirring and reacting for 1h under the conditions of nitrogen and 75 ℃, adding 0.03g of bis- (4-hydroxybenzoyl) -amine and the rest 1/3 of dibutyltin dilaurate, stirring and reacting for 30min, and then placing the mixture at 80 ℃ and rotating for 2h under reduced pressure to obtain a terminal-NCO polyurethane prepolymer, wherein the dosage of dibutyltin dilaurate is 0.01mL;
Step B2: adding 10g of starch and 8g of end-NCO polyurethane prepolymer into a high-speed stirrer, stirring for 10min at a rotating speed of 600rpm, heating to 80 ℃ under the condition of nitrogen, and reducing the rotating speed to 150rpm for continuous reaction for 1h to obtain the modified starch.
Example 2
1) Ce/TiO 2@SiQDs-g-C3N4 is prepared by the steps of:
step A1: adding 8mL of tetrabutyl titanate into a beaker containing 15mL of absolute ethyl alcohol, mixing and stirring for 30min, marking as a mixed solution 1, uniformly stirring and mixing 4.6mL of deionized water, 7mL of glacial acetic acid and 7mL of absolute ethyl alcohol in the beaker, adding 1.5mLPEG-400 and 0.01g of cerium nitrate, mixing and stirring for 30min, marking as a mixed solution 2, slowly dripping the mixed solution 2 into the mixed solution 1 by using a dropping funnel, continuously stirring for 1.5h, standing and ageing for 48h, drying the mixture at a constant temperature of 80 ℃ for 6h, grinding, and roasting in a muffle furnace at 550 ℃ for 2h to obtain Ce/TiO 2;
Step A2: adding 1g of ascorbic acid into 20mL of deionized water, stirring and mixing uniformly, introducing nitrogen into the mixed solution for 20min, adding 1g of Ce/TiO 2 and 50mL of 3-aminopropyl triethoxysilane aqueous solution, continuously stirring for 20min, transferring to an autoclave, placing in a 175 ℃ oven for reaction for 24h, cooling to room temperature after the reaction is finished, dialyzing for 2 days, centrifuging, washing to neutrality, and drying at 60 ℃ for 12h to obtain Ce/TiO 2 @ SiQDs, wherein the 3-aminopropyl triethoxysilane aqueous solution is prepared from 3-aminopropyl triethoxysilane and deionized water in a ratio of 13mL: mixing and stirring the mixture in a dosage ratio of 37 mL;
Step A3: 3g of Ce/TiO 2 @ SiQDs is dispersed in 20mL of deionized water, stirred and mixed uniformly, 0.04g of octadecyl trimethyl ammonium bromide is added, the temperature is raised to 65 ℃, stirring reaction is carried out for 4 hours, and after the reaction is finished, suction filtration and drying are carried out, thus obtaining pretreated Ce/TiO 2 @ SiQDs;
Step A4: urea and dicyandiamide were mixed in a ratio of 7:3, ball milling for 1.5 hours at a rotating speed of 400rpm, grinding 5g of ball milled powder, putting the powder into a ceramic crucible, heating for 4 hours at 550 ℃, grinding the product into powder, transferring the powder into a muffle furnace, heating to 520 ℃, preserving heat for 2 hours, collecting g-C 3N4, dispersing 1.5g g-C 3N4 in 20mL of deionized water, stirring and mixing uniformly, adding 1.7g of pretreatment Ce/TiO 2 @ SiQDs, stirring and mixing to obtain a suspension, carrying out ultrasonic treatment on the suspension for 30 minutes, stirring for 2.5 hours at a rotating speed of 500rpm, filtering, drying, and finally heating the product at 500 ℃ for 2 hours to obtain Ce/TiO 2@SiQDs-g-C3N4.
2) The modified starch is prepared by the following steps:
Step B1: adding 0.4g of polycarbonate dihydric alcohol (M n =2000), 0.025g of isophorone diisocyanate and 10mL of N, N-dimethylformamide into a reactor, stirring and mixing uniformly, then adding 2/3 of dibutyltin dilaurate, stirring and reacting for 1.5h under the conditions of nitrogen and 75 ℃, adding 0.04g of bis- (4-hydroxybenzoyl) -amine and the rest 1/3 of dibutyltin dilaurate, stirring and reacting for 30min, and then placing the mixture at 80 ℃ and rotating for 2h under reduced pressure to obtain a terminal-NCO polyurethane prepolymer, wherein the dosage of dibutyltin dilaurate is 0.02mL;
Step B2: 15g of starch and 10g of end-NCO polyurethane prepolymer are added into a high-speed stirrer, stirred for 10min at the rotating speed of 600rpm, heated to 85 ℃ under the nitrogen condition, and the rotating speed is reduced to 150rpm for continuous reaction for 1.5h, thus obtaining the modified starch.
Example 3
1) Ce/TiO 2@SiQDs-g-C3N4 is prepared by the steps of:
Step A1: adding 10mL of tetrabutyl titanate into a beaker containing 20mL of absolute ethyl alcohol, mixing and stirring for 30min, marking as a mixed solution 1, uniformly stirring and mixing 6.8mL of deionized water, 10mL of glacial acetic acid and 10mL of absolute ethyl alcohol in the beaker, adding 2mLPEG-400 g of cerium nitrate, mixing and stirring for 30min, marking as a mixed solution 2, slowly dripping the mixed solution 2 into the mixed solution 1 by using a dropping funnel, continuously stirring for 2h, standing and ageing for 48h, drying the mixture at a constant temperature of 80 ℃ for 6h, grinding, and roasting in a muffle furnace at 550 ℃ for 2h to obtain Ce/TiO 2;
Step A2: adding 1.2g of ascorbic acid into 24mL of deionized water, stirring and mixing uniformly, introducing nitrogen into the mixed solution for 20min, adding 1.5g of Ce/TiO 2 and 50mL of 3-aminopropyl triethoxysilane aqueous solution, continuously stirring for 20min, transferring to an autoclave, placing in a 200 ℃ oven for reaction for 24h, cooling to room temperature after the reaction is finished, dialyzing for 2 days, centrifuging, washing to neutrality, and drying at 60 ℃ for 12h to obtain the Ce/TiO 2 @ SiQDs, wherein the 3-aminopropyl triethoxysilane aqueous solution is prepared from 3-aminopropyl triethoxysilane and deionized water in a ratio of 16mL:34mL of the mixture is mixed and stirred;
step A3: dispersing 4g of Ce/TiO 2 @ SiQDs in 20mL of deionized water, stirring and mixing uniformly, adding 0.05g of octadecyl trimethyl ammonium bromide, heating to 70 ℃, stirring and reacting for 5 hours, and after the reaction is finished, carrying out suction filtration and drying to obtain pretreated Ce/TiO 2 @ SiQDs;
Step A4: urea and dicyandiamide were mixed in a ratio of 7:3, ball milling for 2 hours at 400rpm, grinding 5g of ball milled powder, putting the powder into a ceramic crucible, heating for 4 hours at 550 ℃, grinding the product into powder, transferring the powder into a muffle furnace, heating to 520 ℃, preserving heat for 2 hours, collecting g-C 3N4, dispersing 2g g-C 3N4 into 20mL of deionized water, stirring and mixing uniformly, adding 2.2g of pretreatment Ce/TiO 2 @ SiQDs, stirring and mixing to obtain a suspension, performing ultrasonic treatment on the suspension for 30 minutes, stirring for 3 hours at 500rpm, filtering and drying after the reaction is finished, and finally heating the product at 500 ℃ for 2 hours to obtain Ce/TiO 2@SiQDs-g-C3N4.
2) The modified starch is prepared by the following steps:
Step B1: adding 0.6g of polycarbonate dihydric alcohol (M n =2000), 0.03g of isophorone diisocyanate and 10mLN, N-dimethylformamide into a reactor, stirring and mixing uniformly, then adding 2/3 of dibutyltin dilaurate, stirring and reacting for 2 hours under the conditions of nitrogen and 75 ℃, adding 0.05g of bis- (4-hydroxybenzoyl) -amine and the rest 1/3 of dibutyltin dilaurate, stirring and reacting for 30 minutes, and then placing the mixture at 80 ℃ and rotating for 2 hours under reduced pressure to obtain a terminal-NCO polyurethane prepolymer, wherein the dosage of dibutyltin dilaurate is 0.03mL;
Step B2: adding 20g of starch and 12g of end-NCO polyurethane prepolymer into a high-speed stirrer, stirring for 10min at a rotating speed of 600rpm, heating to 90 ℃ under the condition of nitrogen, and reducing the rotating speed to 150rpm for continuous reaction for 2h to obtain the modified starch.
Example 4
The preparation method of the photocatalytic degradable starch-based micro plastic comprises the following steps:
40 parts of modified starch prepared in example 1, 8 parts of PVC resin, 5500.1 parts of KH, 3 parts of calcium carbonate, 0.5 part of photocatalyst, 0.5 part of epoxy fatty acid methyl ester and 0.3 part of PE wax; the photocatalyst is Ce/TiO 2@SiQDs-g-C3N4 prepared in example 1;
Step S1: weighing raw materials according to parts by weight, adding the modified starch prepared in the example 1, PVC resin, calcium carbonate and KH550 into a mixer, and mixing for 10min at 110 ℃ to obtain a premix;
Step S2: adding Ce/TiO 2@SiQDs-g-C3N4, epoxy fatty acid methyl ester and PE wax prepared in example 1 into the premix, mixing for 20min, cooling the mixture to 35 ℃, standing at room temperature for 48h, granulating in a screw granulator, and grinding and crushing the plastic particles in a grinder to obtain the photocatalytic degradable starch-based microplastic.
Example 5
The preparation method of the photocatalytic degradable starch-based micro plastic comprises the following steps:
45 parts of modified starch prepared in example 2, 10 parts of PVC resin, 5500.2 parts of KH, 4 parts of calcium carbonate, 1 part of photocatalyst, 0.7 part of epoxy fatty acid methyl ester and 0.5 part of PE wax; the photocatalyst is Ce/TiO 2@SiQDs-g-C3N4 prepared in example 2;
step S1: weighing raw materials according to parts by weight, adding the modified starch prepared in the example 2, PVC resin, calcium carbonate and KH550 into a mixer, and mixing for 15min at 120 ℃ to obtain a premix;
Step S2: adding Ce/TiO 2@SiQDs-g-C3N4, epoxy fatty acid methyl ester and PE wax prepared in example 2 into the premix, mixing for 20min, cooling the mixture to 40 ℃, standing at room temperature for 48h, granulating in a screw granulator, and grinding and crushing the plastic particles in a grinder to obtain the photocatalytic degradable starch-based microplastic.
Example 6
The preparation method of the photocatalytic degradable starch-based micro plastic comprises the following steps:
50 parts of modified starch prepared in example 3, 12 parts of PVC resin, 5500.3 parts of KH, 5 parts of calcium carbonate, 2 parts of photocatalyst, 1 part of epoxy fatty acid methyl ester and 0.8 part of PE wax; the photocatalyst is Ce/TiO 2@SiQDs-g-C3N4 prepared in example 3;
step S1: weighing raw materials according to parts by weight, adding the modified starch prepared in the example 3, PVC resin, calcium carbonate and KH550 into a mixer, and mixing for 20min at 130 ℃ to obtain a premix;
Step S2: adding Ce/TiO 2@SiQDs-g-C3N4, epoxy fatty acid methyl ester and PE wax prepared in example 3 into the premix, mixing for 20min, cooling the mixture to 45 ℃, standing at room temperature for 48h, granulating in a screw granulator, and grinding and crushing the plastic particles in a grinder to obtain the photocatalytic degradable starch-based microplastic.
Comparative example 1
This comparative example is a microplastic, differing from example 6 in that the equivalent amount of TiO 2 nanomaterial was used instead of Ce/TiO 2@SiQDs-g-C3N4 prepared in example 3, the remainder being identical.
Comparative example 2
This comparative example is a microplastic, differing from example 6 in that the modified starch prepared in example 3 is replaced by an equal amount of starch, the remainder being identical.
The microplastic prepared in examples 4 to 6 and comparative examples 1 to 2 was injection molded into standard tensile bars and impact bars, the injection molding temperature was 175 to 185 ℃, the injection molding pressure was 70 to 90MPa, the holding pressure was 45MPa, and the tensile strength and elongation at break thereof were measured according to GB9341-2000 standard. Degradation rate: the microplastic prepared in examples 4-6 and comparative example was blown into a film in a film blowing machine, cut into a 5cm x 2cm sample film, and dried to constant weight at 90 ℃; then paving soil with the thickness of 10cm in a beaker, adjusting the water activity to 15%, then uniformly burying the soil at intervals, applying ultraviolet-visible light irradiation to the beaker, taking out a sample to be tested after 90d, flushing the surface with distilled water, then drying at 90 ℃ to constant weight, and calculating the weight loss rate. The test results are shown in the following table:
| tensile Strength (MPa) | Elongation at break (%) | Degradation rate under illumination (%) | |
| Example 4 | 43.6 | 82.5 | 91.6 |
| Example 5 | 46.1 | 84.8 | 92.4 |
| Example 6 | 50.2 | 89.0 | 93.1 |
| Comparative example 1 | 49.7 | 87.9 | 50.6 |
| Comparative example 2 | 31.4 | 55.6 | 92.7 |
As can be seen from the above table, the prepared microplastic has good tensile strength and elongation at break, and the film prepared from the microplastic has excellent degradation rate under the illumination condition by adding the photocatalyst, so that the microplastic can be widely used for preparing various packaging films, plastic bags and the like.
The above embodiments are only for illustrating the present invention, not for limiting the present invention, and various changes and modifications may be made by one of ordinary skill in the relevant art without departing from the spirit and scope of the present invention, and therefore, all equivalent technical solutions are also within the scope of the present invention, and the scope of the present invention is defined by the claims.
Claims (9)
1. The photocatalytic degradable starch-based micro plastic is characterized by comprising the following raw materials in parts by weight: 40-50 parts of modified starch, 8-12 parts of PVC resin, 0.1-0.3 part of silane coupling agent, 3-5 parts of calcium carbonate, 0.5-2 parts of photocatalyst, 0.5-1 part of plasticizer and 0.3-0.8 part of lubricant;
the photocatalyst is Ce/TiO 2@SiQDs-g-C3N4, and is prepared by the following steps:
step A1: adding tetrabutyl titanate into a beaker containing absolute ethyl alcohol, mixing and stirring for 30min to obtain a mixed solution 1, stirring deionized water, glacial acetic acid and absolute ethyl alcohol in the beaker uniformly, adding PEG-400 and cerium nitrate, mixing and stirring for 30min to obtain a mixed solution 2, slowly dripping the mixed solution 2 into the mixed solution 1 by using a dropping funnel, continuously stirring for 1-2h, standing and aging for 48h, drying the mixture at a constant temperature of 80 ℃ for 6h, grinding, and roasting in a muffle furnace at 550 ℃ for 2h to obtain Ce/TiO 2;
Step A2: adding ascorbic acid into deionized water, stirring and mixing uniformly, introducing nitrogen into the mixed solution for 20min, adding Ce/TiO 2 and 3-aminopropyl triethoxysilane water solution, stirring for 20min, transferring to an autoclave, placing in a baking oven at 170-200 ℃ for reaction for 24h, cooling to room temperature after the reaction is finished, dialyzing for 2 days, centrifuging, washing to neutrality, and drying at 60 ℃ for 12h to obtain Ce/TiO 2 @ SiQDs;
Step A3: dispersing Ce/TiO 2 @ SiQDs in deionized water, stirring and mixing uniformly, adding octadecyl trimethyl ammonium bromide, heating to 60-70 ℃, stirring and reacting for 3-5 hours, and after the reaction is finished, carrying out suction filtration and drying to obtain pretreated Ce/TiO 2 @ SiQDs;
Step A4: urea and dicyandiamide were mixed in a ratio of 7:3, ball milling for 1-2h at 400rpm, grinding 5g of ball milled powder, putting the powder into a ceramic crucible, heating for 4h at 550 ℃, grinding the product into powder, transferring the powder into a muffle furnace, heating to 520 ℃, preserving heat for 2h, collecting g-C 3N4, dispersing g-C 3N4 into deionized water, stirring and mixing uniformly, adding pretreatment Ce/TiO 2 @ SiQDs, stirring and mixing to obtain suspension, performing ultrasonic treatment on the suspension for 30min, stirring for 2-3h at 500rpm, filtering and drying after the reaction is finished, and finally heating the product at 500 ℃ for 2h to obtain Ce/TiO 2@SiQDs-g-C3N4.
2. The photocatalytic degradable starch-based micro plastic according to claim 1, wherein the dosage ratio of tetrabutyl titanate to absolute ethyl alcohol in the mixed solution 1 in the step A1 is 5-10mL:10-20mL; the dosage ratio of deionized water, glacial acetic acid, absolute ethyl alcohol, PEG-400 and cerium nitrate in the mixed solution 2 is 3.4-6.8mL:5-10mL:5-10mL:1-2mL:0.005-0.015g.
3. The photocatalytic degradable starch based micro plastic according to claim 1, wherein the dosage ratio of ascorbic acid, deionized water, ce/TiO 2 and 3-aminopropyl triethoxysilane aqueous solution in step A2 is 0.8-1.2g:16-24mL:0.5-1.5g:50mL of an aqueous solution of 3-aminopropyl triethoxysilane was prepared from 3-aminopropyl triethoxysilane and deionized water in an amount of 10-16mL:34-40mL of the mixture is mixed and stirred.
4. The photocatalytic degradable starch-based micro plastic according to claim 1, wherein in step A3, the dosage ratio of Ce/TiO 2 @ SiQDs, deionized water and octadecyl trimethyl ammonium bromide is 2-4g:20mL:0.03-0.05g.
5. The photocatalytic degradable starch-based micro plastic according to claim 1, wherein the dosage ratio of g-C 3N4, deionized water and pre-treated Ce/TiO 2 @ SiQDs in step A4 is 1-2g:20mL:1.2-2.2g.
6. The photocatalytic degradable starch-based microplastic of claim 1, wherein the modified starch is prepared by the steps of:
Step B1: adding polycarbonate dihydric alcohol, isophorone diisocyanate and N, N-dimethylformamide into a reactor, stirring and mixing uniformly, then adding 2/3 of dibutyltin dilaurate, stirring and reacting for 1-2h under the conditions of nitrogen and 75 ℃, then adding bis- (4-hydroxybenzoyl) -amine and the rest 1/3 of dibutyltin dilaurate, stirring and reacting for 30min, and then placing the mixture at 80 ℃ and rotating for 2h under reduced pressure to obtain the terminal-NCO polyurethane prepolymer;
Step B2: adding starch and the terminal-NCO polyurethane prepolymer into a high-speed stirrer, stirring for 10min at 600rpm, heating to 80-90 ℃ under the condition of nitrogen, and reducing the rotation speed to 150rpm for continuous reaction for 1-2h to obtain the modified starch.
7. The photocatalytic degradable starch based microplastic according to claim 6, characterized in that in step B1 the ratio of polycarbonate diol, isophorone diisocyanate, N-dimethylformamide, dibutyltin dilaurate and bis- (4-hydroxybenzoyl) -amine is 0.2-0.6g:0.02-0.03g:10mL:0.01-0.03mL:0.03-0.05g.
8. The photocatalytic degradable starch based microplastic according to claim 6, wherein the ratio of the amount of starch to the amount of the terminal-NCO polyurethane prepolymer in step B2 is 10-20g:8-12g.
9. The method for preparing the photocatalytic degradable starch-based micro plastic according to claim 1, comprising the steps of:
Step S1: weighing raw materials according to parts by weight, adding modified starch, PVC resin, calcium carbonate and a silane coupling agent into a mixer, and mixing for 10-20min at 110-130 ℃ to obtain a premix;
Step S2: adding a photocatalyst, a plasticizer and a lubricant into the premix, mixing for 20min, cooling the mixture to 35-45 ℃, standing for 48h at room temperature, granulating in a screw granulator, and grinding and crushing the plastic particles in a grinder to obtain the photocatalytic degradable starch-based micro plastic.
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| CN111040392A (en) * | 2019-12-27 | 2020-04-21 | 华东理工大学 | Starch-based degradable material and preparation method and application thereof |
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| CN111040392A (en) * | 2019-12-27 | 2020-04-21 | 华东理工大学 | Starch-based degradable material and preparation method and application thereof |
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