CN115582945A - Device and method for pretreating middle and small-particle-size micro-plastics in soil or sediment - Google Patents
Device and method for pretreating middle and small-particle-size micro-plastics in soil or sediment Download PDFInfo
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- 239000002689 soil Substances 0.000 title claims abstract description 52
- 239000013049 sediment Substances 0.000 title claims abstract description 50
- 229920003023 plastic Polymers 0.000 title claims abstract description 40
- 239000004033 plastic Substances 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 28
- 239000002245 particle Substances 0.000 claims abstract description 137
- 238000005188 flotation Methods 0.000 claims abstract description 101
- 230000002572 peristaltic effect Effects 0.000 claims abstract description 48
- 229920000426 Microplastic Polymers 0.000 claims abstract description 47
- 238000012216 screening Methods 0.000 claims abstract description 33
- 238000003756 stirring Methods 0.000 claims abstract description 19
- 238000000967 suction filtration Methods 0.000 claims abstract description 18
- 239000005416 organic matter Substances 0.000 claims abstract description 15
- 239000000706 filtrate Substances 0.000 claims abstract description 10
- 239000000463 material Substances 0.000 claims abstract description 6
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 20
- 239000012528 membrane Substances 0.000 claims description 20
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims description 18
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 14
- 238000006243 chemical reaction Methods 0.000 claims description 11
- 238000004458 analytical method Methods 0.000 claims description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- 230000008878 coupling Effects 0.000 claims description 9
- 238000010168 coupling process Methods 0.000 claims description 9
- 238000005859 coupling reaction Methods 0.000 claims description 9
- 238000001914 filtration Methods 0.000 claims description 9
- 239000011888 foil Substances 0.000 claims description 9
- 229910001220 stainless steel Inorganic materials 0.000 claims description 9
- 239000010935 stainless steel Substances 0.000 claims description 9
- 238000005303 weighing Methods 0.000 claims description 9
- 239000011592 zinc chloride Substances 0.000 claims description 9
- 235000005074 zinc chloride Nutrition 0.000 claims description 9
- 239000011790 ferrous sulphate Substances 0.000 claims description 7
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 7
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 7
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 7
- 239000011780 sodium chloride Substances 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000007667 floating Methods 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 6
- 229910021642 ultra pure water Inorganic materials 0.000 claims description 6
- 239000012498 ultrapure water Substances 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 5
- 238000002203 pretreatment Methods 0.000 claims description 5
- 239000000843 powder Substances 0.000 claims description 4
- 238000011001 backwashing Methods 0.000 claims description 3
- 238000007664 blowing Methods 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 238000005485 electric heating Methods 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 238000004064 recycling Methods 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 239000002904 solvent Substances 0.000 claims description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 3
- 238000009210 therapy by ultrasound Methods 0.000 claims description 3
- 238000002604 ultrasonography Methods 0.000 claims description 3
- 238000003828 vacuum filtration Methods 0.000 claims description 3
- 238000010521 absorption reaction Methods 0.000 abstract description 7
- 230000000694 effects Effects 0.000 abstract description 6
- 238000002474 experimental method Methods 0.000 description 13
- 239000011148 porous material Substances 0.000 description 6
- 238000000605 extraction Methods 0.000 description 5
- 238000011160 research Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000005457 ice water Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/02—Separating plastics from other materials
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- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Mechanical Engineering (AREA)
- Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
Abstract
The invention discloses a device and a method for pretreating middle and small-particle-size micro-plastics in soil or sediment, wherein the device comprises a flotation system and a particle size grading system, the flotation system comprises a flotation solution storage bottle, a first peristaltic pump and a flotation beaker which are sequentially connected through a pipeline, and materials in the flotation beaker are stirred by a stirring device; the particle size grading system comprises a second peristaltic pump, a filtrate collecting cup, a particle size screening device, a third peristaltic pump and a suction filtration device, the particle size screening device is arranged at a cup opening of the filtrate collecting cup, the flotation beaker is connected with the particle size screening device through the second peristaltic pump, the side wall of the flotation beaker is connected with the particle size screening device through an inclined tube which is inclined downwards, and the filtrate collecting cup is connected with the suction filtration device through the third peristaltic pump. The invention can completely separate and extract the medium and small particle micro plastic in soil or sediment, automatically classify the particle size, reduce the interference of organic matter absorption peak when the extracted micro plastic particles are subjected to microscopic examination, and have better on-machine pretreatment effect.
Description
Technical Field
The invention relates to the technical field of micro-plastic treatment, in particular to a device and a method for pretreating micro-plastic with medium and small particle sizes in soil or sediments.
Background
After the concept of micro plastic is proposed for the first time, the pollution problem is listed as the second most scientific problem in the environmental and ecological fields, and the environmental behavior is not neglected. Relevant studies indicate that the abundance of micro-plastics present in land is likely to be 4-23 times that of the ocean. Therefore, the extraction of micro-plastics from soil and sediments is a serious research effort.
At present, for the extraction of micro-plastics in soil or sediments, a density flotation method is mostly adopted, and flotation devices are diversified, such as: a triangular flask, a beaker, a volumetric flask, and the like. These devices have high requirements on the operating proficiency of operators, and the flotation process is easy to introduce more soil mineral particles and organic matters, so that the subsequent treatment is more complicated and time-consuming. Moreover, only the floated micro-plastic sample is extracted, so that aged micro-plastic particles suspended in the flotation solution are artificially ignored, and result errors are large. In addition, the particle size of the micro plastic particles is not uniform, so that the focusing is not accurate during the machine microscopic examination, and some micro plastic particles with smaller particle size are ignored by the machine. Therefore, the simultaneous extraction of the micro plastic particles after the upper layer flotation and the micro plastic particles suspended in the middle, and the particle size classification before the on-machine analysis are the key for accurately judging the abundance of the micro plastic in the research area. The extraction device for the micro plastic particles has no application precedent in China.
At present, the detection and analysis methods for micro-plastics at home and abroad are not sound, and do not form a whole set of unified standard, particularly, the pretreatment method for micro-plastics is a key step of analysis, is not unified at present, and a perfect pretreatment method needs to be established for environment media such as soil and sediments with high organic matter content, such as lignocellulose, so as to reduce the interference of organic matter absorption peaks when extracted micro-plastic particles are subjected to microscopic examination. Therefore, how to better remove organic matters in soil or sediments without influencing the extraction and microscopic examination of micro plastic particles is a problem to be solved urgently in the pretreatment process at present.
Disclosure of Invention
The invention aims to provide a device and a method for pretreating middle and small particle size micro-plastics in soil or sediments, which are used for solving the problems in the prior art, can thoroughly extract the middle and small particle size micro-plastics in the soil or sediments and classify the particle size, can reduce the interference of organic matter absorption peaks of the extracted micro-plastics particles during microscopic examination, and have better on-machine pretreatment effect.
In order to achieve the purpose, the invention provides the following scheme:
the invention provides a device for pretreating middle and small-particle-size micro-plastics in soil or sediment, which comprises a flotation system and a particle size grading system, wherein the flotation system comprises a flotation liquid storage bottle, a first peristaltic pump and a flotation beaker which are sequentially connected through a pipeline, and materials in the flotation beaker are stirred by a stirring device; particle size grading system includes second peristaltic pump, filtrating collection cup, particle size screening plant, third peristaltic pump and suction filtration device, particle size screening plant set up in the rim of a cup of filtrating collection cup, the flotation beaker passes through the tube coupling the second peristaltic pump, the second peristaltic pump pass through the pipeline with particle size screening plant connects, be equipped with the pipe chute of downward sloping on the flotation beaker lateral wall, the pipe chute accesss to particle size screening plant, the filtrating is collected the cup and is passed through the tube coupling the third peristaltic pump, the third peristaltic pump passes through the tube coupling the suction filtration device.
Preferably, a first pipeline is connected between the first peristaltic pump and the flotation beaker, a second pipeline is connected between the second peristaltic pump and the flotation beaker, and the depth of the first pipeline inserted into the flotation beaker is shallower than the depth of the second pipeline inserted into the flotation beaker.
Preferably, the inclined tube forms an included angle of 30 degrees with the horizontal plane.
Preferably, the particle size screening device comprises a plurality of layers of screens, and in two adjacent layers of screens, the pore diameter of the screen at the upper layer is larger than that of the screen at the lower layer.
Preferably, the stirring device is a magnetic stirrer, and the flotation beaker is placed on the stirring device.
Preferably, the mesh of the uppermost layer has a pore size of 300 μm, and the mesh of the lowermost layer has a pore size of 50 μm; the aperture of the filter membrane in the suction filtration device is 10 mu m.
The invention also provides a method for pretreating micro-plastics with medium and small particle sizes in soil or sediments, which comprises the following steps:
s1: accurately weighing a soil or sediment sample to be tested, carrying out primary screening, and leaving a screened sample to be floated for later use;
s2: preparing a zinc chloride solution, accurately weighing the sample preliminarily screened in the step S1, dissolving the sample in the zinc chloride solution to obtain a prepared solution A, and sealing and standing the prepared solution A overnight;
s3: carrying out classified filtration on the prepared solution A to obtain micro plastic particles with various particle size ranges;
s4: and respectively carrying out an organic matter removal process on the micro plastic particles with different particle size ranges, washing the micro plastic particles with the organic matters removed into a clean beaker by adopting a volatile solvent, and concentrating to obtain an on-machine analysis sample.
Preferably, the preparation of the preparation solution a in the step S2 by using the above-mentioned device for pretreating micro-plastics with small and medium particle sizes in soil or sediments comprises the following steps:
s21: preparing 1.5g/cm 3 Filtering the zinc chloride solution through a filter membrane of 0.45 mu m for later use;
s22: accurately weighing a dried soil or sediment sample in the flotation beaker, and adding the prepared ZnCl into the flotation beaker 2 Pouring the solution into the flotation solution storage bottle, and pumping ZnCl into the first peristaltic pump 2 Transferring the solution into the flotation beaker, starting the stirring device to stir for 2-3 minutes, covering a beaker of the flotation beaker with aluminum foil paper, and standing overnight.
Preferably, in the step S3, the preparation solution a is subjected to classified filtration by using the above-mentioned small and medium-particle-size micro plastic pretreatment device in soil or sediment, and the method comprises the following steps:
s31: placing the flotation solution into the flotation solution storage bottle, slowly introducing the flotation solution into the flotation beaker after standing overnight by adopting the first peristaltic pump again, and discharging micro plastic particles and floating organic impurities into the particle size classification system through the inclined tube under the action of gravity along with the rise of the liquid level in the flotation beaker; the particles suspended in the flotation beaker are introduced into the size classification system by the second peristaltic pump;
s32: the micro plastic and floating organic impurities entering the particle size grading system are graded and screened by the particle size screening device, and the filtered flotation filtrate is transferred to the suction filtration device by the third peristaltic pump;
s33: washing the particle size screening device by using ultrapure water, and performing integral membrane-passing recycling on the flotation filtrate by using the suction filtration device;
s34: and backwashing the particle size screening device by adopting ultrapure water, and collecting micro plastic particles in each particle size range.
Preferably, the step S4 of concentrating by using the above-mentioned device for pretreating micro-plastics with small and medium particle sizes in soil or sediments comprises the following steps:
s41: 500mL of 0.05M ferrous sulfate solution is prepared, and 3mL of concentrated sulfuric acid is added;
s42: transferring the beaker containing organic matters and filled with micro plastic particles with different particle sizes to an electric hot plate, and controlling the temperature to be 50 ℃;
s43: respectively adding a ferrous sulfate solution and 30% hydrogen peroxide into the beaker to remove organic matters, and after the reaction is finished, if the organic matters float, continuously adding 30% hydrogen peroxide for reaction until no organic matters exist;
s44: adding sodium chloride powder into a beaker according to the total amount of the solution, covering a cover of the beaker with aluminum foil paper after the sodium chloride is dissolved, closing an electric heating plate, standing overnight, transferring an upper layer clear solution, and performing vacuum filtration, wherein a filter membrane is a 10-micron stainless steel filter membrane;
s45: taking down the stainless steel filter membrane, placing the stainless steel filter membrane in a beaker, adding an absolute ethyl alcohol solution, covering the beaker with aluminum foil paper, and performing low-frequency ultrasound for 8 hours;
s46: and transferring the solution after ultrasonic treatment to a nitrogen blowing device for solution concentration to obtain an on-machine analysis sample.
Compared with the prior art, the invention has the following technical effects:
according to the device and the method for pretreating medium and small particle size micro-plastics in soil or sediments, provided by the invention, the medium and small particle size micro-plastics in the soil or sediments can be completely extracted and subjected to particle size classification through the flotation system and the particle size classification system, the consumption of the flotation solution in the experimental process is small, the time is saved, and the aperture size of the screen mesh of the particle size screening device in the particle size classification system can be flexibly selected according to the research work requirement; after the medium and small particle micro-plastics in soil or sediment are subjected to particle size classification, organic matter treatment is carried out, so that the interference of organic matter absorption peaks when the extracted micro-plastic particles are subjected to microscopic examination is reduced, and the pre-treatment effect on the machine is better.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be 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 without creative efforts.
FIG. 1 is a schematic structural diagram of a device for pretreating micro-plastics with medium and small particle sizes in soil or sediments, provided by the invention;
FIG. 2 is a flow chart of a method for pretreating micro plastics with small and medium particle sizes in soil or sediments provided by the invention;
in the figure: 1-a flotation solution storage bottle, 2-a first peristaltic pump, 3-a flotation beaker, 4-a stirring device, 5-a second peristaltic pump, 6-a filtrate collection cup, 7-a particle size screening device, 8-a third peristaltic pump, 9-a suction filtration device, 10-an inclined tube, 11-a first pipeline, 12-a second pipeline and 13-a screen.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a device and a method for pretreating middle and small particle size micro-plastics in soil or sediments, which are used for solving the problems in the prior art, can thoroughly extract the middle and small particle size micro-plastics in the soil or sediments and classify the particle size, can reduce the interference of organic matter absorption peaks of the extracted micro-plastics particles during microscopic examination, and have better on-machine pretreatment effect.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1, the present embodiment provides a device for pretreating middle and small-particle-size micro-plastics in soil or sediment, which includes a flotation system and a particle size classification system, wherein the flotation system includes a flotation solution storage bottle 1, a first peristaltic pump 2 and a flotation beaker 3, which are sequentially connected through a pipeline, and a material in the flotation beaker 3 is stirred by a stirring device 4; particle size grading system includes second peristaltic pump 5, cup 6 is collected to the filtrating, particle size screening plant 7, third peristaltic pump 8 and suction filtration device 9, particle size screening plant 7 sets up in the rim of a cup of filtrating collection cup 6, flotation beaker 3 passes through tube coupling second peristaltic pump 5, second peristaltic pump 5 passes through the pipeline and is connected with particle size screening plant 7, be equipped with the pipe chute 10 of downward sloping on the 3 lateral walls of flotation beaker, pipe chute 10 accesss to particle size screening plant 7, cup 6 passes through tube coupling third peristaltic pump 8 is collected to the filtrating, third peristaltic pump 8 passes through tube coupling suction filtration device 9.
When the device is used, the small and medium particles in soil or sediments can be completely extracted through the flotation system and the particle size grading system, the particle size grading is carried out, the use amount of the flotation solution in the experimental process is small, the time is saved, and the aperture size of the screen mesh of the particle size screening device in the particle size grading system can be flexibly selected according to the research work requirement; after the medium and small particle micro plastic in the soil or sediment is subjected to particle size classification, organic matter treatment is carried out, so that the interference of an organic matter absorption peak when the extracted micro plastic particles are subjected to microscopic examination is reduced, and the pre-treatment effect on the machine is better.
In this embodiment, the first pipeline 11 is a pipeline connecting the first peristaltic pump 2 and the flotation beaker 3, the second pipeline 12 is a pipeline connecting the second peristaltic pump 5 and the flotation beaker 3, and the depth of the first pipeline 11 inserted into the flotation beaker 3 is shallower than the depth of the second pipeline 12 inserted into the flotation beaker 3, so that the particles suspended in the flotation beaker 3 can be conveniently introduced into the particle size classification system through the second peristaltic pump 5 via the second pipeline 12.
In this embodiment, the inclined tube 10 forms an angle of 30 ° with the horizontal plane, but other angles may be set in other embodiments.
In this embodiment, the particle size sieving device 7 includes a plurality of layers of screens 13, and in two adjacent layers of screens 13, the upper layer of screens 13 has a larger aperture than the lower layer of screens 13. Specifically, in the present embodiment, the particle size sieving means 7 includes two layers of screens 13.
In this embodiment, the stirring device 4 is a magnetic stirrer, and the flotation beaker 3 is placed on the stirring device 4. The materials in the flotation beaker 3 can be conveniently stirred by a magnetic stirrer. Other automated stirring devices may also be used for the stirring device 4.
In this embodiment, the uppermost screen 13 has a pore size of 300 μm, and the lowermost screen 13 has a pore size of 50 μm; the pore diameter of the filter membrane in the suction filtration device 9 was 10 μm.
As shown in fig. 1-2, a method for pretreating middle and small particle size micro-plastics in soil or sediment, based on the device for pretreating middle and small particle size micro-plastics in soil or sediment, comprises the following steps:
s1: accurately weighing a soil or sediment sample to be tested, performing primary screening, and leaving a screened sample to be floated for later use;
s2: preparing a zinc chloride solution, accurately weighing the sample preliminarily screened in the step S1, dissolving the sample in the zinc chloride solution to obtain a prepared solution A, sealing and standing overnight to prevent micro plastic particles in the air from entering the solution and introducing pollution to the flotation process;
specifically, the step S2 of preparing the prepared solution a by using the above-mentioned medium and small particle size micro plastic pretreatment device in soil or sediment comprises the following steps:
s21: preparing 1.5g/cm 3 Filtering the zinc chloride solution through a 0.45-micron filter membrane for later use;
s22: accurately weighing dried soil or sediment sample with particle size less than 1mmPutting the product in a flotation beaker 3, and adding the prepared ZnCl 2 Pouring the solution into the flotation solution storage bottle, and pumping ZnCl into the first peristaltic pump 2 2 Transferring the solution into a flotation beaker 3, starting a stirring device 4 to stir for 2-3 minutes, covering a beaker of the flotation beaker 3 with aluminum foil paper, and standing overnight;
s3: carrying out classified filtration on the prepared solution A to obtain micro plastic particles with various particle size ranges;
specifically, in the step S3, the step of filtering the prepared solution a by stages by using the above-mentioned small and medium-sized micro plastic pretreatment device in the soil or sediment includes the following steps:
s31: placing the flotation solution into the flotation solution storage bottle, slowly introducing the flotation solution into the flotation beaker 3 which is kept still overnight again by adopting the first peristaltic pump 2, and discharging micro plastic particles and floating organic impurities into a particle size classification system through the inclined tube 10 under the action of gravity along with the rise of the liquid level in the flotation beaker 3; the particles suspended in the flotation beaker 3 are introduced into the particle size classification system by means of a second peristaltic pump 5;
s32: micro plastic and floating organic impurities entering a particle size grading system are graded and screened by a particle size screening device 7, and filtered flotation filtrate is transferred to a suction filtration device 9 by a third peristaltic pump 8;
s33: washing the particle size screening device 7 by using ultrapure water, and performing integral membrane-passing recycling on the flotation filtrate by using a suction filtration device 9;
s34: backwashing the particle size screening device 7 by using ultrapure water, and collecting micro plastic particles in each particle size range;
s4: respectively carrying out an organic matter removal process on the micro plastic particles with different particle size ranges, washing the micro plastic particles with the organic matters removed into a clean beaker by adopting a volatile solvent, and concentrating to obtain an on-machine analysis sample;
specifically, the step S4 of concentrating by using the above-mentioned device for pretreating micro-plastics with small and medium particle sizes in soil or sediments includes the following steps:
s41: 500mL of 0.05M ferrous sulfate solution is prepared, and 3mL of concentrated sulfuric acid is added;
s42: transferring the beaker containing organic matters and filled with micro plastic particles with different particle sizes to an electric hot plate, and controlling the temperature to be 50 ℃;
s43: respectively adding a ferrous sulfate solution and 30% hydrogen peroxide into the beaker to remove organic matters, wherein the organic matters are subjected to a violent reaction process during reaction, at the moment, the beaker is transferred into ice water to be cooled, so that micro plastic particles are prevented from being deformed due to overhigh reaction temperature, and after the reaction is finished, if the organic matters float, the 30% hydrogen peroxide is continuously added for reaction until no organic matters exist;
s44: adding sodium chloride powder into a beaker according to the total amount of the solution, adding about 7g of sodium chloride powder into every 20mL of the solution, covering a cover of the beaker with aluminum foil paper after the sodium chloride is dissolved, closing an electric heating plate, standing overnight, transferring an upper clear solution, and performing vacuum filtration, wherein a filter membrane is a 10-micron stainless steel filter membrane;
s45: taking down the stainless steel filter membrane, placing the stainless steel filter membrane in a beaker, adding an absolute ethyl alcohol solution, covering an aluminum foil paper on the beaker, and performing low-frequency ultrasound for 8 hours;
s46: and transferring the solution after ultrasonic treatment to a nitrogen blowing device for solution concentration, and concentrating to about 1ml to obtain an on-machine analysis sample, which can be used for analysis on a machine.
The method places the micro plastic particles in an absolute ethyl alcohol matrix, after the absolute ethyl alcohol is volatilized, the micro plastic particles are flatly laid on the microscopic examination window sheet, so that the frequent focusing of an instrument caused by insufficient flatness of the filter membrane during microscopic examination focusing and the fact that the filter membranes made of different materials are easy to have infrared absorption peaks can be avoided, and the detection precision and speed of the micro plastic are ensured.
Comparative test
In the comparative experiment, the same amount of park soil samples are subjected to comparative experiments of organic matter treatment before flotation (experiment 1) and organic matter treatment after flotation (experiment 2). In the experiment 1, a large amount of bubbles are generated during the removal of organic matters, the amount of 30% hydrogen peroxide is about 1000mL, after the reaction is finished, water in a sample is evaporated by means of heating evaporation, and then a subsequent flotation experiment is carried out, but the situation that organic matter particles are not completely removed is still found, and secondary treatment is still carried out in the subsequent experiment. In the development process of experiment 2, organic matters in the sieved sample are directly removed, ferrous sulfate and 30% hydrogen peroxide are added for reaction, and finally the amount of the required hydrogen peroxide is about 120mL, so that compared with experiment 1, the amount of the required hydrogen peroxide is greatly reduced. As can be seen from comparison of reaction time, the time for completing the flotation experiment in experiment 1 is 5 days, and the time for completing the flotation experiment in experiment 2 is 2 days, so that the time is saved.
The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. A device for pretreating middle and small-particle-size micro-plastics in soil or sediments is characterized in that: the flotation system comprises a flotation system and a particle size grading system, wherein the flotation system comprises a flotation liquid storage bottle, a first peristaltic pump and a flotation beaker which are sequentially connected through a pipeline, and materials in the flotation beaker are stirred by a stirring device; particle size grading system includes second peristaltic pump, filtrating collection cup, particle size screening plant, third peristaltic pump and suction filtration device, particle size screening plant set up in the rim of a cup of filtrating collection cup, the flotation beaker passes through the tube coupling the second peristaltic pump, the second peristaltic pump pass through the pipeline with particle size screening plant connects, be equipped with the pipe chute of downward sloping on the flotation beaker lateral wall, the pipe chute accesss to particle size screening plant, the filtrating is collected the cup and is passed through the tube coupling the third peristaltic pump, the third peristaltic pump passes through the tube coupling the suction filtration device.
2. The apparatus for pretreating middle and small-sized micro plastics in soil or sediments as claimed in claim 1, wherein: the pipeline connecting the first peristaltic pump and the flotation beaker is a first pipeline, the pipeline connecting the second peristaltic pump and the flotation beaker is a second pipeline, and the depth of the first pipeline inserted into the flotation beaker is shallower than the depth of the second pipeline inserted into the flotation beaker.
3. The device for pretreating middle and small-particle-size micro-plastics in soil or sediments as claimed in claim 1, wherein: the inclined tube and the horizontal plane form an included angle of 30 degrees.
4. The device for pretreating middle and small-particle-size micro-plastics in soil or sediments as claimed in claim 1, wherein: the particle size screening device comprises a plurality of layers of screens, wherein in the two adjacent layers of screens, the aperture of the screen on the upper layer is larger than that of the screen on the lower layer.
5. The device for pretreating middle and small-particle-size micro-plastics in soil or sediments as claimed in claim 1, wherein: the stirring device is a magnetic stirrer, and the flotation beaker is placed on the stirring device.
6. Device for the pre-treatment of micro-plastics with small and medium grain size in the soils or sediments as claimed in claim 4, characterized in that: the aperture of the screen mesh at the uppermost layer is 300 microns, and the aperture of the screen mesh at the lowermost layer is 50 microns; the aperture of the filter membrane in the suction filtration device is 10 mu m.
7. A method for pretreating micro-plastics with medium and small particle sizes in soil or sediments is characterized by comprising the following steps: the method comprises the following steps:
s1: accurately weighing a soil or sediment sample to be tested, carrying out primary screening, and leaving a screened sample to be floated for later use;
s2: preparing a zinc chloride solution, accurately weighing the sample preliminarily screened in the step S1, dissolving the sample in the zinc chloride solution to obtain a prepared solution A, and sealing and standing the prepared solution A overnight;
s3: carrying out classified filtration on the prepared solution A to obtain micro plastic particles with various particle size ranges;
s4: and respectively carrying out an organic matter removal process on the micro plastic particles with different particle size ranges, washing the micro plastic particles with the organic matters removed into a clean beaker by adopting a volatile solvent, and concentrating to obtain an on-machine analysis sample.
8. The method for pretreating middle and small-particle-size microplastics in soil or sediments as claimed in claim 7, wherein the preparation solution A is prepared in step S2 by using the middle and small-particle-size microplastics pretreatment device in soil or sediments as claimed in any one of claims 1-6, and comprises the following steps:
s21: preparing 1.5g/cm 3 Filtering the zinc chloride solution through a 0.45-micron filter membrane for later use;
s22: accurately weighing a dried soil or sediment sample in the flotation beaker, and adding the prepared ZnCl into the flotation beaker 2 Pouring the solution into the flotation solution storage bottle, and pumping ZnCl into the first peristaltic pump 2 Transferring the solution into the flotation beaker, starting the stirring device to stir for 2-3 minutes, covering a beaker of the flotation beaker with aluminum foil paper, and standing overnight.
9. The method for pretreating middle and small-particle-size microplastics in soil or sediments as claimed in claim 8, wherein step S3 is implemented by classifying and filtering the preparation solution A by using the device for pretreating middle and small-particle-size microplastics in soil or sediments as claimed in any one of claims 1-6, and comprises the following steps:
s31: placing the flotation solution into the flotation solution storage bottle, slowly introducing the flotation solution into the flotation beaker after standing overnight by adopting the first peristaltic pump again, and discharging micro plastic particles and floating organic impurities into the particle size classification system through the inclined tube under the action of gravity along with the rise of the liquid level in the flotation beaker; the particles suspended in the flotation beaker are introduced into the size classification system by the second peristaltic pump;
s32: the micro plastic and floating organic impurities entering the particle size grading system are graded and screened by the particle size screening device, and the filtered flotation filtrate is transferred to the suction filtration device by the third peristaltic pump;
s33: washing the particle size screening device by using ultrapure water, and performing integral membrane-passing recycling on the flotation filtrate by using the suction filtration device;
s34: and backwashing the particle size screening device by adopting ultrapure water to collect micro plastic particles in each particle size range.
10. The method for pretreating middle and small-particle-size micro-plastics in soil or sediments as claimed in claim 7, wherein the step S4 of concentrating by using the device for pretreating middle and small-particle-size micro-plastics in soil or sediments as claimed in any one of claims 1-6 comprises the following steps:
s41: 500mL of 0.05M ferrous sulfate solution is prepared, and 3mL of concentrated sulfuric acid is added;
s42: transferring the beaker containing the organic matters and filled with the micro plastic particles with different particle sizes to an electric hot plate, and controlling the temperature to be 50 ℃;
s43: respectively adding a ferrous sulfate solution and 30% hydrogen peroxide into the beaker to remove organic matters, and after the reaction is finished, if the organic matters float, continuously adding 30% hydrogen peroxide for reaction until no organic matters exist;
s44: adding sodium chloride powder into a beaker according to the total amount of the solution, covering a cover of the beaker with aluminum foil paper after the sodium chloride is dissolved, closing an electric heating plate, standing overnight, transferring an upper layer clear solution, and performing vacuum filtration, wherein a filter membrane is a 10-micron stainless steel filter membrane;
s45: taking down the stainless steel filter membrane, placing the stainless steel filter membrane in a beaker, adding an absolute ethyl alcohol solution, covering the beaker with aluminum foil paper, and performing low-frequency ultrasound for 8 hours;
s46: and transferring the solution after the ultrasonic treatment to a nitrogen blowing device for solution concentration to obtain an on-machine analysis sample.
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| CN202211173567.XA CN115582945A (en) | 2022-09-26 | 2022-09-26 | Device and method for pretreating middle and small-particle-size micro-plastics in soil or sediment |
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| CN106179773A (en) * | 2015-05-06 | 2016-12-07 | 中国科学院烟台海岸带研究所 | The continuous flow separation flotation unit of a kind of microparticle plastics and method |
| CN113155558A (en) * | 2021-02-05 | 2021-07-23 | 北京市理化分析测试中心 | Method for extracting, separating and purifying micro-plastic in soil |
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| CN114273379A (en) * | 2021-12-29 | 2022-04-05 | 西南科技大学 | Continuous flow separation flotation system for soil micro-plastic |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106179773A (en) * | 2015-05-06 | 2016-12-07 | 中国科学院烟台海岸带研究所 | The continuous flow separation flotation unit of a kind of microparticle plastics and method |
| CN213943506U (en) * | 2020-08-14 | 2021-08-13 | 深圳中绿环境集团有限公司 | Separating device for micro-plastic |
| CN113155558A (en) * | 2021-02-05 | 2021-07-23 | 北京市理化分析测试中心 | Method for extracting, separating and purifying micro-plastic in soil |
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