CN113150516B - Polylactic acid-based layered nano modified membrane and preparation method and application thereof - Google Patents
Polylactic acid-based layered nano modified membrane and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a polylactic acid-based layered nano modified membrane and a preparation method and application thereof. Blending and modifying polylactic acid by adopting a biodegradable high polymer material, promoting polymer intermolecular reaction to generate long-chain branched polylactic acid (LC-PLA) under the action of a chain extender, and then loading calcium peroxide-loaded layered filler with a micro-nano-sized structure domain into organic intercalated bentonite (B) by a layered nano-filler compounding method CaO2 ) Dispersed in a LC-PLA matrix, B CaO2 The platelets tend to orient in the flow direction, which can significantly improve the strength of the modified film. The physical barrier effect of the modified film can prevent the diffusion of the peculiar smell substances to form a macroscopic barrier layer; in the membrane B CaO2 The method can improve the tortuosity of the transmission path of the peculiar smell substances, prolong the path of diffusing peculiar smell molecules into air, form a microcosmic permeation barrier, and can be used for long-acting diffusion control of the peculiar smell substances in the non-disturbed interface soil in the pesticide industry field.
Description
Technical Field
The invention relates to the technical field of in-situ remediation of organic pollution production places, in particular to a polylactic acid-based layered nano modified membrane and a preparation method and application thereof.
Background
A great amount of organic solvent raw and auxiliary materials are used in the production process of pesticide enterprises, and if production accidents such as running, leakage, dripping and leakage occur, the materials enter environmental media such as soil and underground water and are difficult to naturally degrade in a short period of time, and become a pollutant sustained release source after annual accumulation. At present, commercially available odor diffusion control materials mainly include plant extracts, microbial agents, foam-type odor inhibitors, and the like, and are mostly used as emergency control. The research on long-time odor diffusion control materials in non-disturbed fields is less, and no commercial product is found yet.
The biodegradable film can be used for long-acting diffusion control of odor substances in non-disturbed fields in the pesticide industry by matching with a corresponding covering and sealing technology, but the film made of common biodegradable materials (such as PLA and the like) has the problems of poor mechanical property, high gas transmittance, no odor substance decomposition function and the like. Therefore, the research and development of a membrane with good mechanical property and an odor substance decomposition function is the main research direction at present.
Disclosure of Invention
The invention aims to provide a polylactic acid-based layered nano modified membrane, and a preparation method and application thereof, so as to solve the problems in the prior art. The polylactic acid based layered nano modified membrane can be used for controlling the diffusion of the odor substances on the undisturbed interface in the pesticide industry field, can effectively adsorb and degrade the odor substances entering the pores of the membrane on the basis of realizing the high-efficiency physical barrier of the odor substances, prolongs the diffusion control time of the odor substances and obviously reduces the diffusion flux of the odor substances. The matrix polylactic acid (PLA) and the high polymer material particles of the modified film are biodegradable high polymer/copolymer; organic intercalation bentonite (B) of layered nano filler loaded with calcium peroxide CaO2 ) In the bentonite, non-metallic mineral with montmorillonite as main component and CaO 2 Is a non-toxic oxidant. The preparation process of the modified film does not add toxic or harmful additives, and the modified film laid in situ does not need to be recycled after losing the effects of blocking foreign matters and adsorbing and degrading, and does not produce secondary pollution to soil.
In order to achieve the purpose, the invention provides the following scheme: the invention provides a preparation method of a polylactic acid based layered nano modified film, which comprises the following steps: blending biodegradable high molecular material and polylactic acid, adding chain extender to prepare long-chain branched polylactic acid (LC-PLA), and then adding organic intercalation bentonite (B) loaded with oxidant CaO2 ) Dispersing in a long-chain branched polylactic acid matrix, granulating to obtain a membrane-making master batch, and making a membrane by using the membrane-making master batch to obtain a polylactic acid-based layered nano modified membrane;
the biodegradable high polymer material comprises at least one of polybutylene adipate terephthalate (PBAT), Polycaprolactone (PCL), polybutylene succinate (PBSA), polyethylene succinate (PES) and polybutylene adipate terephthalate (PTMAT);
the chain extender is a multi-epoxy functional group chain extender and comprises
ADR- 4300、
ADR-4370、
ADR-4468、KL-E4300、KL- E4370、FINE-BLEND TM One of SAG-008;
the oxidant is calcium peroxide.
The PLA comprises one of NatureWorks 3052D, 4032D, 6062D, 6204D and DadalLX 175 as further optimization of the invention, and the PBAT comprises one of Xinjiang Lantun river THJS-5801, THJS-6801, THJS-7801, TH801T, Basovi C1200 and ecovi 1335.
Firstly, carrying out long-chain branching modification on PLA blending by using a biodegradable high polymer material, and improving the interface compatibility of the blend through reactive blending with a multi-epoxy functional group chain extender so as to improve the toughness of the material and obtain LC-PLA; with lamellar nanofillers B CaO2 As a filling reinforcing material, the LC-PLA material has the function of oxidizing and degrading peculiar smell substances while further enhancing the barrier property of the LC-PLA material. Determining B according to the composition, characteristics and concentration of peculiar smell substances in pesticide industry field CaO2 The prepared modified film is laid on a soil interface of a non-disturbed field in the pesticide industry, and except for the physical barrier effect, the modified film B in the film CaO2 Can form a microcosmic barrier, efficiently adsorb and degrade peculiar smell substances entering pores of the membrane, and realize long-acting diffusion control of the peculiar smell substances in the soil.
As a further optimization of the invention, the method comprises the following steps:
(1) carrying out vacuum drying treatment on polylactic acid particles and biodegradable high polymer material particles; the vacuum drying is drying treatment for 12-24 hours in a vacuum drying oven at 60 ℃;
(2) uniformly mixing the polylactic acid particles and the biodegradable high polymer material particles which are dried in the step (1) with a multi-epoxy functional group chain extender to obtain a premixed material A;
(3) granulating the premixed material A obtained in the step (2), and drying in vacuum to obtain long-chain branched chain polylactic acid particles;
(4) putting bentonite and an organic modifier into water, stirring at 800-1200 rpm until the bentonite is emulsion, adding an acetic acid solution in which chitosan is dissolved, ultrasonically dispersing for 30-90 min, then performing suction filtration to obtain a precipitate, washing the precipitate, drying, grinding and sieving to obtain the organic modified bentonite;
(5) putting calcium chloride and a cationic surfactant into water, performing ultrasonic dispersion for 30-90 min, adding the organic modified bentonite obtained in the step (4), and continuing performing ultrasonic treatment for 60-120 min to obtain a first mixed solution; uniformly mixing ammonia water and hydrogen peroxide under the stirring condition of 100-250 rpm to obtain a second mixed solution; uniformly mixing the first mixed solution and the second mixed solution under the stirring condition of 300-500 rpm to obtain a third mixed solution, reacting, controlling the temperature of the third mixed solution to be 20-30 ℃ in the reaction process, leaching and taking precipitate after the reaction is finished, washing the precipitate, drying, and grinding to obtain the calcium peroxide loaded organic intercalated bentonite (B) CaO2 )；
(6) Uniformly mixing the long-chain branch polylactic acid particles and the organic intercalation bentonite powder loaded with calcium peroxide to obtain a premixed material B;
(7) granulating the premixed material B, and carrying out vacuum drying treatment for 12-24 hours to obtain a film-making master batch;
(8) the polylactic acid-based layered nano modified film is obtained by using the film-making master batch to make the film.
As a further optimization of the invention, the mass ratio of the polylactic acid particles, the biodegradable polymer material particles and the multi-epoxy functional group chain extender in the step (2) is 60: 40: 0.1-0.5; the mixing is carried out in a high-speed mixer at the rotation speed of 800-1200 rpm for 10-30 min;
and (3) granulating by adopting a double-screw extruder at the temperature of 165-210 ℃, rotating the screw at 30-60 rpm, and carrying out vacuum drying at the temperature of 60 ℃ for 12-24 h.
As a further optimization of the invention, the mass ratio of the organic modifier, the bentonite and the chitosan in the step (4) is (1-10) to 100 to (1-3) in sequence, and the bentonite is sodium bentonite (B) with the particle size of 6.5-75 mu m Na ) (ii) a The organic modifier is a long-carbon-chain quaternary ammonium salt organic modifier, the acetic acid solution is an acetic acid water solution with the mass concentration of 1 wt% -3 wt%, the washing precipitation comprises 2-3 times of washing with an ethanol solution and distilled water respectively, the drying is carried out at the temperature of 80-120 ℃, and the sieving is 200 meshes;
the long-carbon-chain quaternary ammonium salt organic modifier comprises hexadecyl trimethyl ammonium chloride (CTAC);
as a further optimization of the invention, in the step (5), the mass ratio of the calcium chloride, the organically modified bentonite and the cationic surfactant is (100-300) to 100 to (1-10) in sequence, the cationic surfactant is cetyl trimethyl quaternary ammonium bromide (CTAB), the mass ratio of the hydrogen peroxide to the calcium chloride is (8-4) to 1, the content of ammonia water in the second mixed solution is 1.5-5.5 wt%, and the ammonia water is concentrated ammonia water with the volume concentration of more than or equal to 28%; washing the precipitate for 2-3 times by using distilled water; the drying temperature is 80-120 ℃; the grinding is carried out by adopting a ball mill, and the final grinding granularity is 0.1-20 mu m; the mass ratio of the bentonite to the calcium peroxide in the calcium peroxide-loaded organic intercalated bentonite is 1: 0.2-0.3.
As a further optimization of the invention, the mass ratio of the long-chain branched polylactic acid particles in the step (6) to the calcium peroxide-loaded organic intercalated bentonite powder is 100: 1-5; the mixing is carried out in a high-speed mixer at 1200-2000 rpm for 10-30 min;
and (7) granulating by using a double-screw extruder again, wherein the temperature is 145-195 ℃, and the screw revolution is 30-60 rpm.
As a further optimization of the invention, the film preparation in the step (8) is carried out by adopting a single-screw extrusion blow molding machine, the temperature is 175-190 ℃, the screw revolution is 20-80 rpm, the blowing-up ratio is 2: 1-6: 1, the winding speed is 2-8 m/min, and the finally obtained film thickness is 50-300 mu m.
The invention also provides a polylactic acid-based layered nano modified film prepared by the preparation method.
The invention also provides application of the polylactic acid-based layered nano modified film in long-acting control of the peculiar smell substances, and B can be determined according to the composition, the characteristics and the concentration of the peculiar smell substances CaO2 The prepared modified film is laid on the soil interface of the non-disturbed field of pesticide industry, and except the physical barrier effect, the modified film B in the film CaO2 Can form a microcosmic barrier, efficiently adsorb and degrade peculiar smell substances entering pores of the membrane, and can be used for long-acting diffusion control of the peculiar smell substances in the non-disturbed interface soil in the pesticide industry field.
The invention discloses a polylactic acid-based layered nano modified film, wherein the mechanical properties (toughness and the like) of polylactic acid are effectively improved after the polylactic acid is subjected to branched modification by a long-chain branch, the regularity of macromolecules can be reduced, and the film forming strength and the biodegradation rate are improved. Meanwhile, the lamellar filler (bentonite) with a nano structure can be dispersed into the polylactic acid through a lamellar nano filler composite method, the organic intercalation modified bentonite has better compatibility and dispersibility in a polylactic acid matrix, and the single-layer peeling of the lamella can obviously increase the tortuosity of a permeation path of the odor substances under the action of high shear force, further reduce the gas permeability of the modified film and improve the physical barrier capability of the odor substances; in addition, nanometer-micron calcium peroxide particles are generated among the bentonite layered structures through an in-situ reaction process, hydrogen peroxide can be slowly released under the action of soil water vapor/sprayed water, the continuous degradation of the odor substances in a certain time is realized, the diffusion flux is obviously reduced while sufficient adsorption sites of the filler are ensured, and the long-range adsorption and the efficient degradation of the odor substances are realized. Meanwhile, aiming at the composition, characteristics (oxidation degradation difficulty) and concentration of the foreign flavor substances, a targeted modified membrane material combination measure can be provided. The method can be used for long-acting diffusion control of the odor substances in the non-disturbed interface soil in the pesticide industry. The polymer/layered nano inorganic composite material can be prepared by a melt blending method, the filler is dispersed in a blend matrix under the action of high temperature and high shear, a solvent is not required to be used, and the prepared composite material has good mechanical property and is easy to realize industrial production.
The invention discloses the following technical effects:
the invention has the advantages that the modified film can realize high-efficiency macroscopic physical barrier of peculiar smell substances, the layered nano filler can be used as a microscopic barrier to efficiently adsorb and degrade peculiar smell substances entering pores of the film, raw materials required by film preparation comprise biodegradable high polymer materials, nontoxic and harmless nonmetallic minerals and oxidizing agents, no toxic and harmful solvent/reagent is added in the preparation process, the modified film laid in situ does not need to be recycled after losing peculiar smell substance barrier and adsorption degradation effects, and the film preparation raw materials PLA and the high polymer materials are biodegradable materials, so that biodegradation can be completed under the action of soil microorganisms. Therefore, the polylactic acid based layered nano modified membrane does not cause adverse effects on the environment from the raw materials to the production and application processes, and does not have the risk of secondary pollution.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.
FIG. 1 shows B obtained in example 1 CaO2 Wherein a is B CaO2 Observation of the powder, B is B CaO2 Scanning electron microscope of the powder, c is B CaO2 A powder XRD pattern;
FIG. 2 is a film observation view, a film transmission electron microscope view and a partially enlarged view of b of the polylactic acid-based layered nano-modification film obtained in example 1;
fig. 3 is a graph showing the mechanical property test results of the polylactic acid film prepared in comparative example 1 and the polylactic acid-based layered nano-modified film prepared in example 1, and b is a graph showing the mechanical property test results of the polylactic acid-based layered nano-modified film prepared in example 1;
fig. 4 is a gas barrier property test chart of the polylactic acid film prepared in comparative example 1 and the polylactic acid-based layered nano-modified film prepared in example 1, wherein a is a gas barrier property test result chart of the polylactic acid film prepared in comparative example 1, and b is a gas barrier property test result chart of the polylactic acid-based layered nano-modified film prepared in example 1;
fig. 5 is a schematic view of a soil odor substance barrier property verification device in experimental example 1, wherein 1 is a nitrogen gas cylinder; 2 is a flowmeter; 3 is a soil groove sealing cover; 4 is a soil groove; 5 is a pollutant storage pool; 6 is a pollutant supplementing pipe; 7 is a pollutant injector; 8 is a direct current heating rod; 9 is a temperature control power supply; 10 is a pollutant absorption bottle;
fig. 6 is a graph showing the results of the experiments for verifying the barrier properties of the soil odor substances in experimental example 1.
Detailed Description
Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but rather as a more detailed description of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made to the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including but not limited to.
Example 1
(1) Preparation of LC-PLA:
sequentially weighing a PLA material NatureWorks4032D, a PBAT material Xinjiang Lantun river TH801T and an ADR material according to the mass ratio of 60: 40: 0.5
ADR 4468. Drying the weighed PLA and PBAT particles in a vacuum drying oven at 60 ℃ for 12h, then putting the dried PLA and PBAT particles and ADR into a high-speed mixer, and mixing for 15min at 800rpm to obtain a premixed material A; and extruding and granulating the premixed material A by a double-screw extruder at the temperature of 165 ℃ and the screw revolution of 35rpm, and then performing vacuum drying for 12 hours at the temperature of 60 ℃ to obtain LC-PLA granules.
(2)B CaO2 The preparation of (1):
b with the particle size of 20 mu m is weighed according to the mass ratio of 100: 5: 1 Na CTAC, and chitosan.
Dissolving CTAC in distilled water, mixing well, adding B Na Stirring the mixture in a water bath kettle at 60 ℃ at 1000rpm until the mixture is emulsion; adding chitosan solution prepared by dissolving chitosan in 1% acetic acid solution, ultrasonically dispersing for 60min, vacuum filtering, cleaning the product with ethanol solution for 3 times, and cleaning with distilled water for 3 timesDrying at 102 ℃, grinding and sieving with a 200-mesh sieve to obtain the organically modified bentonite.
Weighing CaCl according to the mass ratio of 300: 100: 2 2 Organically modified bentonite and CTAB in accordance with H 2 O 2 With CaCl 2 Weighing H according to the mass ratio of 4: 1 2 O 2 。
Dissolving CTAB in distilled water, mixing well, adding CaCl 2 Ultrasonically dispersing for 90min, then adding organic modified bentonite, and continuously ultrasonically dispersing for 120min to obtain a first mixed solution; stirring at 150rpm to H 2 O 2 Adding 30% ammonia water, and uniformly mixing to obtain a second mixed solution, wherein the content of the ammonia water in the second mixed solution is 4.5 wt%; uniformly mixing the first mixed solution and the second mixed solution under the stirring condition of 300rpm to obtain a third mixed solution, reacting, controlling the temperature of the third mixed solution to be 20 ℃ in the reaction process, after the reaction is finished, carrying out suction filtration to obtain a precipitate, washing the precipitate for 3 times by using distilled water, drying at 102 ℃, putting the dried precipitate into a ball mill for grinding, and finally obtaining the calcium peroxide loaded organic intercalated bentonite powder B with the particle size of 5 mu m CaO2 B prepared by detection CaO2 Specific surface area of 70.92m 2 Is obviously higher than the specific surface area of raw bentonite of 61.23m 2 The calcium peroxide loading can reach 31.6 wt%.
(3) Preparation of polylactic acid based layered nano modified membrane:
sequentially weighing LC-PLA and B according to the mass ratio of 100: 3 CaO2 Weighing LC-PLA and B CaO2 Putting the mixture into a high-speed mixer, and mixing for 20min at the rotation speed of 1500rpm to obtain a premixed material B; putting the premixed material B into a double-screw extruder, and extruding and granulating at the temperature of 160 ℃ and the screw revolution of 60rpm to obtain film-making master batches; and (3) putting the film-making master batch into a single-screw extrusion blow molding machine, wherein the temperature is 175 ℃, the screw revolution is 20rpm, the blowing-up ratio is 3: 1, and the winding speed is 4m/min, so that the polylactic acid-based layered nano modified film with the film thickness of 200 mu m is finally obtained.
B prepared in this example CaO2 Appearance observation picture, electron microscope scanning picture and transmission electron microscope picture of the powder,see fig. 1. B prepared in this example CaO2 The loading capacity of the calcium peroxide can reach 31.6 wt%, the particle size of calcium peroxide particles is between 20nm and 2 mu m, and the interlayer dispersion effect is best; after organic modification, the space between bentonite layers is enlarged to 1.166 times of that of the original soil.
The observation and transmission electron microscope images of the polylactic acid-based layered nano-modified film prepared in this example are shown in fig. 2, in which a is an observation of a piece of paper with patterns placed below the polylactic acid-based layered nano-modified film. As can be seen from fig. 2, the polylactic acid based layered nano modified film prepared in this example has high transparency under indoor light conditions; under a transmission electron microscope, the bentonite lamella in the modified film and the loaded calcium peroxide nano-particles are clearly visible. The modified bentonite is effectively dispersed in a polymer matrix and stripped from a single layer, so that pores on the surface of the barrier film can be effectively blocked, a gas permeation path is effectively prolonged, and the permeation of gas is blocked to a certain degree. In addition, CaO is carried on the bentonite lamellae 2 The particles can increase the roughness of a gas permeation path, can also improve the hydrophobicity of the film, and is also beneficial to gas barrier.
Comparative example 1
Placing PLA material NatureWorks4032D into a single-screw extrusion blow molding machine, wherein the temperature is 175 ℃, the screw revolution is 20rpm, the blow-up ratio is 3: 1, the winding speed is 4m/min, and finally obtaining the polylactic acid film with the film thickness of 200 mu m.
The polylactic acid film prepared in comparative example 1 and the polylactic acid-based layered nano-modified film prepared in example 1 were subjected to mechanical property tests, and the results are shown in fig. 3. As can be seen from fig. 3, the elongation at break of the polylactic acid film prepared in comparative example 1 is only 28.17%, which shows strong brittleness, while the elongation at break of the polylactic acid-based layered nano modified film prepared in example 1 is as high as 412.76%, which significantly improves mechanical properties.
The gas barrier properties of the polylactic acid film prepared in comparative example 1 and the polylactic acid-based layered nano-modified film prepared in example 1 were tested, and the results are shown in fig. 4. As can be seen from FIG. 4, the polylactic acid film prepared in comparative example 1 has high gas permeability, and the gas permeation rate is as high as 1699.37 cc/m 2 Day, prepared as in example 1The prepared polylactic acid-based layered nano modified film has the air permeability of only 44.89 cc/(m) 2 Day). The modified film has low gas permeability, not only can play an effective physical barrier role, but also can load CaO in the film 2 The bentonite can also effectively adsorb and degrade the odor substances entering the pores of the membrane along with the soil water vapor, so that the diffusion flux of the odor substances can be effectively reduced.
Experimental example 1
The polylactic acid-based layered nano modified film prepared in example 1 was used as an experimental object to perform a soil odor substance barrier property verification experiment.
The experimental device for verifying the barrier property of the soil odor substances is shown in figure 5. The direct current heating rod is used for heating soil, and the peculiar smell substance resistance and control effect of the modified membrane under the high-temperature condition (high peculiar smell substance release flux) is simulated.
The experimental device assembly was performed as shown in the schematic diagram of the soil odor blocking performance verification device of fig. 5. The polylactic acid-based layered nano modified film prepared in example 1 was covered on the soil in the treatment group, and the soil surface was not covered with the modified film in the control group. The processing group seals the contact boundary of the modified film and the organic glass by an adhesive tape, and simultaneously carries out secondary sealing by glass cement, thereby avoiding pollutants from escaping from a connecting gap. The experimental conditions were as follows: size of soil groove 4: the length is 20cm, the width is 20cm, the height is 20cm, the bottom of the inner part is filled with quartz sand (20 meshes and 6cm in height), clean soil (4 cm in height and 25% of water content) is filled above the quartz sand, and a heating rod 8 is arranged on the quartz sand layer. The soil groove 4 top is equipped with the sealed lid 3 of soil groove, then seals with the pollutant filling opening, heating rod socket with silica gel stopper and glass glue. 10g of dimethyl disulfide, 10g of paraxylene and 10g of trichloroethylene are injected into the contaminant reservoir 5 through the contaminant supplement pipe 6 by the contaminant injector 7, and the central temperature of the quartz sand layer is heated to 60 ℃ by the heating rod 8 by turning on the temperature control power supply 9. Opening nitrogen cylinder 1, inject clean nitrogen gas from device one end through flowmeter 2 restriction certain gas flow rate, the gas outlet of the other end absorbs the peculiar smell material with the pollutant recovery bottle 10 that is filled with n-hexane, sets up two pollutant recovery bottles 10 in order to ensure that the peculiar smell material is by whole absorption, experimental period 14d, the peculiar smell material concentration in the pollutant recovery bottle is surveyed regularly during the period, calculates peculiar smell material release flux and diffusion inhibition rate. The results are shown in FIG. 6.
The experimental result shows that in the contrast experiment, all the peculiar smell substances released by the soil are absorbed by the n-hexane in the first absorption bottle. Along with the extension of the heating time, the water content of the soil is continuously reduced, the odor substances can rapidly penetrate through the soil pores to enter air, so that the diffusion flux of the odor substances in the control experiment is gradually increased along with the extension of the time, and the diffusion flux is dimethyl disulfide>Xylene>Trichloroethylene. Wherein, the diffusion flux of dimethyl disulfide, toluene and trichloroethylene in the control group at 14 days is respectively 483.59mg/m at 1 day 2 ·d、256.47 mg/m 2 ·d、188.1mg/m 2 D is increased to 5014.26mg/m 2 ·d、4462.76mg/m 2 ·d、 3396.23mg/m 2 D, diffusion flux of dimethyl disulfide, xylene, trichloroethylene at 1d and 14d in the treatment group covering the modified membrane is only 13.28mg/m 2 D and 241.05mg/m 2 ·d，7.47mg/m 2 D and 296.38mg/m 2 ·d，16.65mg/m 2 D and 345.87mg/m 2 D. The gas permeability of the multi-effect barrier modified film in the treatment group experiment is low, not only can play an effective physical barrier role, but also the CaO loaded in the film 2 The bentonite can also effectively adsorb and degrade peculiar smell substances entering pores of the membrane along with soil water vapor, so that the diffusion flux of the peculiar smell substances can be effectively reduced, and the diffusion fluxes of dimethyl disulfide, xylene and trichloroethylene after the modified membrane is covered for 14d can be respectively reduced by 89.8%, 93.4% and 95.2%.
Example 2
(1) Preparation of LC-PLA:
sequentially weighing a PLA material NatureWorks4032D, a PBAT material Sinkiang Lanshantun river TH801T and an ADR material according to the mass ratio of 60: 40: 0.1
ADR 4468. Drying the weighed PLA and PBAT granules in a vacuum drying oven at 60 ℃ for 24h, and then putting the dried PLA, PBAT granules and ADR into a high-speed mixerMixing the mixture for 10min at 1200rpm to obtain a premixed material A; and extruding and granulating the premixed material A by a double-screw extruder at the temperature of 180 ℃ and the screw revolution of 30rpm, and then carrying out vacuum drying for 24h at the temperature of 60 ℃ to obtain LC-PLA granules.
(2)B CaO2 The preparation of (1):
b with the particle size of 6.5 mu m is weighed according to the mass ratio of 100: 3: 2 in turn Na CTAC, and chitosan.
Dissolving CTAC in distilled water, mixing well, adding B Na Stirring at 1200rpm in a water bath kettle at 60 ℃ until the mixture is emulsion; adding chitosan solution prepared by dissolving chitosan in 2% acetic acid solution, performing ultrasonic dispersion for 90min, performing suction filtration, cleaning the product with ethanol solution for 2 times, cleaning with distilled water for 3 times, drying at 80 ℃, grinding, and sieving with 200 mesh sieve to obtain the organic modified bentonite.
Weighing CaCl according to the mass ratio of 200: 100: 6 2 Organically modified bentonite and CTAB according to the formula H 2 O 2 With CaCl 2 Weighing H according to the mass ratio of 6: 1 2 O 2 。
Dissolving CTAB in distilled water, mixing well, adding CaCl 2 Carrying out ultrasonic dispersion for 60min, then adding organic modified bentonite, and continuing to carry out ultrasonic dispersion for 60min to obtain a first mixed solution; stirring at 100rpm to H 2 O 2 Adding 35% ammonia water, and uniformly mixing to obtain a second mixed solution, wherein the content of the ammonia water in the second mixed solution is 1.8 wt%; uniformly mixing the first mixed solution and the second mixed solution under the stirring condition of 420rpm to obtain a third mixed solution, reacting, controlling the temperature of the third mixed solution to be 25 ℃ in the reaction process, after the reaction is finished, carrying out suction filtration to obtain a precipitate, washing the precipitate for 3 times by using distilled water, drying at 80 ℃, putting the dried precipitate into a ball mill for grinding, and finally obtaining the calcium peroxide-loaded organic intercalation bentonite powder B with the particle size of 10 mu m CaO2 . B prepared by detection CaO2 The specific surface area is 78.62m 2 Calcium peroxide loading was 34.1 wt. -%.
(3) Preparation of polylactic acid based layered nano modified film:
sequentially weighing LC-PLA and B according to the mass ratio of 100: 1 CaO2 Weighing LC-PLA and B CaO2 Putting the mixture into a high-speed mixer, and mixing for 10min at the rotating speed of 2000rpm to obtain a premixed material B; putting the premixed material B into a double-screw extruder, and extruding and granulating at the temperature of 145 ℃ and the screw revolution of 50rpm to obtain film-making master batches; and (3) putting the film-making master batch into a single-screw extrusion blow molding machine, and finally obtaining the polylactic acid-based layered nano modified film with the film thickness of 50 mu m at the temperature of 190 ℃, the screw revolution of 60rpm, the blow-up ratio of 6: 1 and the winding speed of 8 m/min.
Example 3
(1) Preparation of LC-PLA:
sequentially weighing a PLA material NatureWorks4032D, a PBAT material Xinjiang Lantun river TH801T and an ADR material according to the mass ratio of 60: 40: 0.3
ADR 4468. Drying the weighed PLA and PBAT particles in a vacuum drying oven at 60 ℃ for 19h, then putting the dried PLA and PBAT particles and ADR into a high-speed mixer, and mixing for 30min at 1000rpm to obtain a premixed material A; and extruding and granulating the premixed material A by a double-screw extruder at the temperature of 210 ℃ and the screw revolution of 60rpm, and then drying in vacuum for 20 hours at the temperature of 60 ℃ to obtain LC-PLA granules.
(2)B CaO2 The preparation of (1):
b with the particle size of 75 mu m is weighed according to the mass ratio of 100: 7: 3 Na CTAC, and chitosan.
Dissolving CTAC in distilled water, mixing well, adding B Na Stirring the mixture in a water bath kettle at the temperature of 60 ℃ at 800rpm until the mixture is emulsion; adding chitosan solution prepared by dissolving chitosan in 3% acetic acid solution, performing ultrasonic dispersion for 30min, performing suction filtration, cleaning the product with ethanol solution for 2 times, cleaning with distilled water for 2 times, drying at 120 ℃, grinding, and sieving with 200 mesh sieve to obtain the organic modified bentonite.
Weighing CaCl according to the mass ratio of 100: 10 in turn 2 Organically modified bentonite and CTAB in accordance with H 2 O 2 With CaCl 2 Weighing H according to the mass ratio of 8: 1 2 O 2 。
Dissolving CTAB in distilled water, mixing well, adding CaCl 2 Carrying out ultrasonic dispersion for 30min, then adding organic modified bentonite, and continuing to carry out ultrasonic dispersion for 100min to obtain a first mixed solution; to H under stirring at 250rpm 2 O 2 Adding ammonia water with the concentration of 40%, and uniformly mixing to obtain a second mixed solution, wherein the content of the ammonia water in the second mixed solution is 5.5 wt%; uniformly mixing the first mixed solution and the second mixed solution under the stirring condition of 500rpm to obtain a third mixed solution, reacting, controlling the temperature of the third mixed solution to be 30 ℃ in the reaction process, after the reaction is finished, carrying out suction filtration to obtain a precipitate, washing the precipitate for 2 times by using distilled water, drying at 120 ℃, putting the dried precipitate into a ball mill for grinding, and finally obtaining the calcium peroxide loaded organic intercalated bentonite powder B with the granularity of 20 mu m CaO2 . B prepared by detection CaO2 The specific surface area is 63.47m 2 Calcium peroxide loading was 25.3 wt./g.
(3) Preparation of polylactic acid based layered nano modified film:
sequentially weighing LC-PLA and B according to the mass ratio of 100: 5 CaO2 Weighing LC-PLA and B CaO2 Putting the mixture into a high-speed mixer, and mixing for 30min at the rotation speed of 1200rpm to obtain a premixed material B; putting the premixed material B into a double-screw extruder, and extruding and granulating at the temperature of 195 ℃ and the screw revolution of 50rpm to obtain film-making master batches; and (3) putting the film-making master batch into a single-screw extrusion blow molding machine, and finally obtaining the polylactic acid-based layered nano modified film with the film thickness of 300 mu m at the temperature of 180 ℃, the screw revolution of 20rpm, the blow-up ratio of 2: 1 and the winding speed of 2 m/min.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention may be made by those skilled in the art without departing from the spirit of the present invention, which is defined by the claims.
Claims (7)
1. The application of the polylactic acid-based layered nano modified film in long-acting control of the odor substances is characterized in that the polylactic acid-based layered nano modified film is laid on a soil interface of a non-disturbance site in the pesticide industry and is used for long-acting diffusion control of the odor substances in the soil of the non-disturbance site in the pesticide industry;
the preparation method of the polylactic acid based layered nano modified membrane comprises the following steps:
(1) carrying out vacuum drying treatment on polylactic acid particles and biodegradable high polymer material particles;
(2) uniformly mixing the polylactic acid particles and the biodegradable high polymer material particles which are dried in the step (1) with a multi-epoxy functional group chain extender to obtain a premixed material A;
(3) granulating the premixed material A obtained in the step (2), and drying in vacuum to obtain long-chain branched polylactic acid particles;
(4) putting bentonite and an organic modifier into water, stirring until the bentonite and the organic modifier are in an emulsion state, adding an acetic acid solution in which chitosan is dissolved, performing ultrasonic dispersion for 30-90 min, performing suction filtration to obtain a precipitate, washing the precipitate, drying, grinding and sieving to obtain the organically modified bentonite;
(5) putting calcium chloride and a cationic surfactant into water, performing ultrasonic dispersion for 30-90 min, adding the organic modified bentonite obtained in the step (4), and continuing performing ultrasonic treatment for 60-120 min to obtain a first mixed solution; uniformly mixing ammonia water and hydrogen peroxide under the stirring condition to obtain a second mixed solution; uniformly mixing the first mixed solution and the second mixed solution under the condition of stirring to obtain a third mixed solution, reacting, carrying out suction filtration after the reaction is finished to obtain a precipitate, washing the precipitate, drying, and grinding to obtain calcium peroxide-loaded organic intercalated bentonite powder;
(6) uniformly mixing the long-chain branched polylactic acid particles with calcium peroxide-loaded organic intercalated bentonite to obtain a premixed material B;
(7) granulating the premixed material B, and carrying out vacuum drying treatment for 12-24 hours to obtain a membrane-making master batch;
(8) preparing a film by using the film-preparing master batch to obtain a polylactic acid-based layered nano modified film;
the biodegradable high polymer material comprises at least one of polybutylene adipate-terephthalate, polycaprolactone, polybutylene succinate, polyethylene succinate and polybutylene adipate-terephthalate.
2. The application of the polylactic acid-based layered nano modified film in long-acting control of odor substances according to claim 1, wherein the mass ratio of the polylactic acid particles, the polybutylene adipate terephthalate particles and the multi-epoxy functional group chain extender in the step (2) is 60: 40: 0.1-0.5; the mixing is carried out for 10-30 min at the rotation speed of 800-1200 rpm.
3. The application of the polylactic acid based layered nano modified film in long-acting control of odor substances according to claim 1, wherein in the step (3), the granulation is carried out at the temperature of 165-210 ℃ and the screw revolution of 30-60 rpm, and the vacuum drying treatment time is 12-24 h.
4. The application of the polylactic acid-based layered nano modified film in long-acting control of odor substances according to claim 1, wherein the mass ratio of the organic modifier, the bentonite and the chitosan in the step (4) is (1-10) to 100 to (1-3) in sequence, and the bentonite is sodium bentonite with the particle size of 6.5-75 μm; the organic modifier is a long carbon chain quaternary ammonium salt organic modifier, the acetic acid solution is an acetic acid aqueous solution with the mass concentration of 1 wt% -3 wt%, the washing precipitation comprises washing 2-3 times with an ethanol solution and distilled water respectively, and the drying is carried out at the temperature of 80-120 ℃.
5. The application of the polylactic acid based layered nano modified membrane in long-acting control of odor substances according to claim 1, wherein in the step (5), the mass ratio of the calcium chloride, the organically modified bentonite and the cationic surfactant is (100-300) to 100 to (1-10) in sequence, the cationic surfactant is cetyl trimethyl quaternary ammonium bromide, the mass ratio of the hydrogen peroxide to the calcium chloride is (8-4) to 1, and the content of ammonia water in the second mixed solution is 1.5-5.5 wt%; the drying temperature is 80-120 ℃; the final grinding particle size of the grinding is 0.1-20 μm; the mass ratio of the bentonite to the calcium peroxide in the calcium peroxide-loaded organic intercalated bentonite is 1: 0.2-0.3.
6. The application of the polylactic acid-based layered nano modified film in long-acting control of odor substances according to claim 1, wherein the mass ratio of the long-chain branched polylactic acid particles in the step (6) to the calcium peroxide-loaded organic intercalated bentonite powder is 100: 1-5; the mixing is carried out for 10-30 min at the rotation speed of 1200-2000 rpm;
and (7) granulating at the temperature of 145-195 ℃ and the screw revolution of 30-60 rpm.
7. The application of the polylactic acid based layered nano modified film in long-acting control of odor substances according to claim 1, wherein the film preparation conditions in the step (8) are 175-190 ℃ of temperature, 20-80 rpm of screw rotation, 2: 1-6: 1 of blow-up ratio and 2-8 m/min of winding speed.
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