Pretreatment Device for Heavy Metal Detection in Plastic Products

Abstract

The present invention discloses a pretreatment device for detecting heavy metals in plastic products, which comprises: a digestion mechanism, which includes a heating jacket, an outer housing, a plurality of circulation pipes, an inner housing, a cover body, an exhaust pipe, a digestion solution supply mechanism and an acid discharge mechanism. The present invention can provide a closed reaction condition for the pretreatment digestion of plastic samples, can automatically add acid, and can also stir the digestion solution and plastic samples to a large extent, thereby improving the rate and degree of the digestion reaction, improving the pretreatment efficiency of plastic samples, and improving the accuracy of detecting heavy metals in plastic samples.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic product detection. More specifically, the present invention relates to a pretreatment device for detecting heavy metals in plastic products. Background Art

[0002] Food packaging safety is one of the important links in food safety management. Plastic packaging is widely used in the field of food packaging due to its wide range of raw material sources, variety of types, easy processing, low cost, excellent waterproof and moisture-proof performance, etc. In order to ensure food safety and reduce or avoid secondary pollution to the environment caused by plastic products, the detection of toxic substances in plastic products is the focus of food safety supervision, especially the detection of heavy metals in plastic products, which requires strict control and supervision.

[0003] During the detection of heavy metals in plastic products, it is necessary to carry out digestion pretreatment on the plastic products. Specifically, plastic products are soaked with strongly oxidizing acids such as nitric acid, perchloric acid, hydrofluoric acid, sulfuric acid, and hydrogen peroxide to destroy components such as organic matter or silicate in the plastic products; the sample solution after digestion is fixed to a preset volume, and then the analysis and detection of heavy metal content are carried out.

[0004] Most of the existing digestion pretreatment devices for plastic products add acid manually, which brings great potential safety hazards to operators and the laboratory environment; in the patent with the application number 201010570536.9, a sample digestion treatment device is disclosed, which discloses a solvent supply mechanism that can be used for automatic acid addition instead of manual acid addition. At the same time, a deflection motor and an oscillation plate are also provided to oscillate the test tubes on the test tube rack back and forth. Although the above patent solves the problem of automatic acid addition, it does not involve acid discharge. The acid gas generated during the digestion process will evaporate into the air, causing pollution to the environment and harm to the health of operators; in addition, the combined effect of the deflection motor and the oscillation plate recorded in the above patent can only make the test tubes shake slightly, and the stirring effect of the solvent and the sample is poor, and the digestion reaction cannot be effectively accelerated. Summary of the Invention

[0005] One object of the present invention is to solve at least the above problems and provide at least the advantages described later.

[0006] Another object of the present invention is to provide a pretreatment device for detecting heavy metals in plastic products, which solves the technical defects in the prior art that the acid gas generated during the digestion reaction is directly discharged, resulting in air pollution, and the stirring amplitude during the digestion reaction is too small to effectively accelerate the digestion reaction.

[0007] To achieve these objects and other advantages of the present invention, there is provided a pretreatment device for detecting heavy metals in plastic products, which includes:

[0008] Digestion mechanism, comprising:

[0009] Heating jacket;

[0010] Outer shell, which is a hollow cylinder with a spherical bottom structure, and the bottom of the outer shell is located inside the heating jacket;

[0011] Multiple circulation pipes, which are arranged at intervals along the circumferential direction outside the outer shell. The lower end of any circulation pipe communicates with the lower part of the outer shell, and the upper end communicates with the upper part of the outer shell; a one-way valve is provided at the upper end of any circulation pipe;

[0012] Inner shell, which is coaxially sleeved inside the outer shell and has the same structure as the outer shell. A plurality of first through holes are provided on the side wall of the inner shell; the plastic sample to be detected is accommodated inside the inner shell;

[0013] Cover body, which is used to seal and cover the top of the outer shell. A second through hole is provided in the middle of the cover body, and a first slider is provided on one side wall of the second through hole; a feeding port is provided on the cover body, and a baffle for opening and closing is provided inside;

[0014] Exhaust pipe, one end of which is located inside the inner shell, and the other end vertically passes through the second through hole and extends above the cover body. A spiral groove is provided on the circumferential outer wall of the exhaust pipe along the vertical direction, and the first slider is slidably arranged in the spiral groove; the exhaust pipe is fixedly connected to the inner shell, and a plurality of exhaust holes are arranged at intervals on the exhaust pipe;

[0015] Digestion liquid supply mechanism, which communicates with the inside of the outer shell;

[0016] Acid discharge mechanism, which communicates with the other end of the exhaust pipe.

[0017] Preferably, for the pretreatment device for detecting heavy metals in plastic products, the digestion mechanism further includes:

[0018] First ring, which is horizontally arranged at the top of the inner shell. The center of the first ring is located on the axis of the inner shell. The outer circular edge of the first ring is fixedly connected to the inner wall of the inner shell through a plurality of first connecting rods; annular first sliding rails are provided on both the top surface and the bottom surface of the first ring;

[0019] Second ring, which is horizontally and concentrically sleeved inside the first ring. The inner circular edge of the second ring is fixedly connected to the exhaust pipe through a plurality of second connecting rods; annular second sliding rails are provided on both the top surface and the bottom surface of the second ring;

[0020] A plurality of second sliders are arranged at intervals in the circumferential direction between the first ring and the second ring. The top and bottom ends of any one second slider are respectively slidably clamped in two first slide rails, and the top and bottom ends of the other end are respectively slidably clamped in two second slide rails. A third through hole is provided through the middle of the second slider in the vertical direction;

[0021] A plurality of brush rods, one second slider is correspondingly provided with one brush rod. The upper end of any one brush rod is fixedly connected to the bottom of the cover body, and the lower end vertically passes through the corresponding third through hole and extends to the inside of the inner shell. Any one brush rod is slidably connected with the corresponding third through hole in the vertical direction. The lower end of the brush rod is provided with bristles that contact the inner wall of the inner shell.

[0022] Preferably, for the pretreatment device for detecting heavy metals in plastic products, the digestion mechanism further includes an air guide pipe, the lower end of which is rotationally and hermetically connected to the exhaust pipe through a connecting pipe, and the upper end is communicated with the acid discharge mechanism. The air guide pipe is a corrugated pipe body; the bottom of the connecting pipe is rotationally and hermetically communicated with the other end of the exhaust pipe through a bearing, and the top is hermetically communicated with the lower end of the air guide pipe. The upper part of the connecting pipe is connected to the free end of a vertically lifting electric telescopic rod through a third connecting rod.

[0023] Preferably, for the pretreatment device for detecting heavy metals in plastic products, a regulating valve is provided inside the exhaust pipe, and it includes:

[0024] A regulating pipe, which is a hollow frustum structure coaxially sleeved inside the exhaust pipe; the regulating pipe is larger at the top and smaller at the bottom;

[0025] A sealing plug, which is a conical structure that can block the bottom of the regulating pipe;

[0026] A guiding cylinder, which is coaxially arranged inside the exhaust pipe and above the sealing plug. The top of the guiding cylinder is fixedly connected to the inner wall of the exhaust pipe through a fourth connecting rod;

[0027] A movable rod, which is coaxially arranged inside the exhaust pipe and between the sealing plug and the guiding cylinder. The lower end of the movable rod is fixedly connected to the top of the sealing plug, and the upper end is inserted into the inside of the guiding cylinder and connected to the inner top surface of the guiding cylinder through a spring; the movable rod is slidably connected with the guiding cylinder in the vertical direction.

[0028] Preferably, for the pretreatment device for detecting heavy metals in plastic products, a sealing gasket is provided on the inner wall of the second through hole in a ring shape.

[0029] Preferably, for the pretreatment device for detecting heavy metals in plastic products, the digestion liquid supply mechanism includes:

[0030] A digestion liquid storage tank;

[0031] The pump body, its inlet end is communicated with the digestion solution storage tank through a first liquid guide pipe, and its outlet end is communicated with the inside of the outer shell through a second liquid guide pipe. A flow meter is provided on the second liquid guide pipe near the outer shell.

[0032] Preferably, for the pretreatment device for detecting heavy metals in the plastic products, the acid discharging mechanism includes:

[0033] A first lye cylinder, one side of which is hermetically communicated with the top of the air guide pipe through a first air pipe, and the lower end of the first air pipe extends to the bottom of the first lye cylinder;

[0034] A second lye cylinder, one side of which is communicated with the other side of the first lye cylinder through a second air pipe. One end of the second air pipe is located in the upper part of the first lye cylinder, and the other end extends to the bottom of the second lye cylinder; A third air pipe communicating with the outside is provided on the other side of the second lye cylinder.

[0035] Preferably, the pretreatment device for detecting heavy metals in the plastic products further includes a cover body. The digestion mechanism, the digestion solution supply mechanism and the acid discharging mechanism are all encapsulated in the cover body. The top surface of the cover body is an openable and closable panel; The free end of the third air pipe extends out of the cover body.

[0036] The present invention has at least the following beneficial effects:

[0037] In the present invention, the inner shell is set to be in the structure of a net pocket. The digestion solution and the plastic sample are respectively accommodated in the outer shell and the inner shell. Further, the inner shell and the outer shell are movably connected through an exhaust pipe, and the digestion solution and the plastic sample move relatively, playing a role of stirring, accelerating the digestion reaction rate and increasing the digestion degree of the sample; The present invention can provide a closed reaction condition for the pretreatment digestion of plastic samples, can automatically add acid, and can also stir the digestion solution and the plastic sample to a large extent, thereby improving the digestion reaction rate and digestion degree, improving the pretreatment efficiency of plastic samples, and improving the accuracy of detecting heavy metals in plastic samples; In practical applications, the outer shell and the inner shell can be made of transparent materials, and the experimenter can directly and conveniently observe the digestion degree of the plastic sample. When the inner shell moves upward relative to the outer shell above the liquid level of the digestion solution, it can be clearly observed whether the sample in the inner shell is digested completely; Setting multiple circulation pipes realizes the recycling of the digestion solution, improves the utilization rate of the digestion solution, increases the contact rate between the digestion solution and the plastic sample, and further accelerates the digestion rate.

[0038] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will be understood by those skilled in the art through the research and practice of the present invention. Description of the Drawings

[0039] Figure 1 This is a schematic structural diagram of a pretreatment device for detecting heavy metals in plastic products described in one technical solution of the present invention;

[0040] Figure 2 This is a top view of the inner housing, the first ring, the second ring, and the exhaust pipe in another technical solution of the present invention;

[0041] Figure 3 This is a schematic structural diagram of the regulating valve described in another technical solution of the present invention;

[0042] Figure 4 This is a schematic structural diagram of the regulating valve described in another technical solution of the present invention.

[0043] Explanation of reference numerals: 1 - heating jacket; 2 - outer housing; 21 - circulation pipe; 22 - digestion liquid storage tank; 23 - pump body; 24 - first liquid guide pipe; 25 - second liquid guide pipe; 3 - inner housing; 4 - cover body; 5 - exhaust pipe; 51 - adjusting pipe; 52 - sealing plug; 53 - guiding cylinder; 54 - fourth connecting rod; 55 - movable rod; 56 - spring; 6 - brush rod; 71 - first lye cylinder; 72 - second lye cylinder; 73 - first air pipe; 74 - second air pipe; 75 - third air pipe; 81 - first ring; 82 - first connecting rod; 83 - second ring; 84 - second connecting rod; 85 - second slider; 851 - third through hole; 91 - air guide pipe; 92 - connecting pipe; 93 - third connecting rod; 94 - electric telescopic rod; 10 - cover body. Detailed implementation manners

[0044] The following further describes the present invention in detail with reference to the drawings and embodiments, so that those skilled in the art can implement it according to the description in the specification.

[0045] It should be understood that terms such as "having", "comprising", and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0046] It should be noted that the experimental methods described in the following implementation schemes are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0047] In the description of the present invention, the orientation or positional relationship indicated by terms such as "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention.

[0048] As Figures 1 to 4 shown, the present invention provides a pretreatment device for detecting heavy metals in plastic products, which includes:

[0049] A digestion mechanism, which includes:

[0050] A heating sleeve 1;

[0051] An outer shell 2, which is a hollow cylinder with a spherical bottom structure, and the bottom of the outer shell 2 is located inside the heating sleeve 1;

[0052] A plurality of circulation pipes 21, which are arranged at intervals along the circumferential direction outside the outer shell 2. The lower end of any one of the circulation pipes 21 is communicated with the lower part of the outer shell 2, and the upper end is communicated with the upper part of the outer shell 2; a one-way valve is provided at the upper end of any one of the circulation pipes 21;

[0053] An inner shell 3, which is coaxially sleeved inside the outer shell 2 and has the same structure as the outer shell 2. A plurality of first through holes are provided on the side wall of the inner shell 3; the plastic sample to be detected is accommodated inside the inner shell 3;

[0054] A cover 4, which is used to seal and cover the top of the outer shell 2. A second through hole is provided in the middle of the cover 4, and a first slider is provided on one side wall of the second through hole; a feeding port is provided on the cover 4, and a baffle for opening and closing is provided inside it; the feeding port can be sealed and covered by the baffle. Two feeding ports can be symmetrically arranged, and a handle is provided on each baffle to facilitate the opening and closing of the baffle;

[0055] An exhaust pipe 5, one end of which is located inside the inner shell 3, and the other end vertically passes through the second through hole and extends above the cover 4. A spiral groove is provided on the circumferential outer wall of the exhaust pipe 5 along the vertical direction, and the first slider slides in the spiral groove; the exhaust pipe 5 is fixedly connected to the inner shell 3, and a plurality of exhaust holes are arranged at intervals on the exhaust pipe 5;

[0056] A digestion solution supply mechanism, which is communicated with the inside of the outer shell;

[0057] An acid discharge mechanism, which is communicated with the other end of the exhaust pipe.

[0058] The present invention discloses a pretreatment device for detecting heavy metals in plastic products, which includes a heating jacket for heating to provide heat for the digestion reaction. The outer shell of the hollow cylinder is used to accommodate the digestion solution. The digestion solution inside the outer shell is heated under the action of the heating jacket to meet the high-temperature reaction conditions required for the digestion reaction. The structure of the heating jacket is the same as that of the bottom of the outer shell, so that the digestion solution inside the outer shell is heated more evenly. A plurality of circulation pipes are arranged circumferentially outside the outer shell to realize the recycling of the digestion solution. A one-way valve is arranged at the upper end of the circulation pipe (steam enters from the upper end of the circulation pipe and discharges from the lower end), so that the heated digestion solution inside the outer shell enters the circulation pipe in the state of steam (acid gas) at the upper part of the outer shell, and then returns to the lower part of the outer shell through the lower end of the circulation pipe for the digestion reaction. The digestion solution inside the outer shell moves upward from the lower part of the outer shell and returns to the lower part of the outer shell through the circulation pipe, which can increase the contact area between the digestion solution and the sample to be processed (plastic products), improve the digestion degree of the sample, and further improve the accuracy of heavy metal detection in the sample. An inner shell is sleeved inside the outer shell, and a plurality of first through holes are arranged on the side wall of the inner shell, so that the digestion solution inside the outer shell can enter the inside of the inner shell through the first through holes and react with the plastic sample (the crushed material of the plastic product) inside the inner shell. A cover body is arranged at the top of the outer shell, which can seal and cover the top of the outer shell to provide a closed condition for the digestion reaction. The cover body and the outer shell are designed to be detachably connected, and the cover body can be removed before and after the reaction. The excessive acid gas generated by the digestion reaction can be discharged through the exhaust pipe to avoid excessive air pressure inside the outer shell. The exhaust pipe is fixedly connected to the inner shell and is movably connected to the second through hole on the outer shell through the cooperation design of the slider and the spiral groove (while the exhaust pipe moves up and down relative to the outer shell, it can also rotate around the axis of the outer shell), thereby realizing the movable connection between the inner shell and the outer shell (the inner shell can move up and down relative to the outer shell and rotate around the axis of the inner shell). The digestion solution supply mechanism is used to supply the digestion solution to the inside of the outer shell, and the acid discharge mechanism is used to consume the acid gas generated during the digestion reaction to avoid air pollution caused by the direct discharge of acid gas.

[0059] In the present invention, the inner shell is arranged in a structure within a net bag, and the digestion solution and the plastic sample are respectively accommodated in the outer shell and the inner shell. Further, the inner shell and the outer shell are movably connected through an exhaust pipe, and the digestion solution and the plastic sample move relatively, playing a role in stirring, accelerating the digestion reaction rate and increasing the digestion degree of the sample. The present invention can provide a closed reaction condition for the pretreatment digestion of plastic samples, can automatically add acid, and can also stir the digestion solution and the plastic sample to a large extent, thereby improving the digestion reaction rate and digestion degree, improving the pretreatment efficiency of plastic samples, and improving the accuracy of heavy metal detection in plastic samples. In practical applications, the outer shell and the inner shell can be made of transparent materials, and experimental personnel can directly and conveniently observe the digestion degree of the plastic sample. When the inner shell moves upward relative to the outer shell above the liquid level of the digestion solution, it can be clearly observed whether the sample in the inner shell is completely digested. The setting of multiple circulation pipes realizes the recycling of the digestion solution, improves the utilization rate of the digestion solution, increases the contact rate between the digestion solution and the plastic sample, and further accelerates the digestion rate.

[0060] In the above technical solution, the crushed product of the plastic product to be detected is placed in the inner shell through the feeding port, and the feeding port is sealed and covered by closing the baffle. The cover body is hermetically connected to the top edge of the outer shell (the inner shell, the exhaust pipe, and the cover body are an integrally connected structure. The exhaust pipe can move up and down relative to the cover body and rotate around the axis of the exhaust pipe. The exhaust pipe is coaxially arranged with the inner shell). The exhaust pipe is communicated with the acid discharge mechanism, and the outer shell is communicated with the digestion solution supply mechanism. The digestion solution is introduced into the interior of the outer shell through the digestion solution supply mechanism, and the introduction amount of the digestion solution is determined according to the amount of the crushed plastic product, realizing the automatic and quantitative addition of the digestion solution. The digestion solution enters the inner shell from the outer shell through a plurality of first through holes on the inner shell and reacts with the plastic product inside the inner shell. During the digestion reaction, the digestion solution is heated and circulates back into the digestion system in the form of steam through a plurality of circulation pipes. The excessive acid gas generated can be consumed through the exhaust pipe via the acid discharge mechanism. During the digestion process, the exhaust pipe moves up and down relative to the outer shell, driving the inner shell to move up and down relative to the outer shell. At the same time, the first slider slides in the spiral groove. Under the mutual cooperation of the first slider and the spiral groove, the exhaust pipe is driven to make a circular motion around its own axis, and then the inner shell is driven to move up and down relative to the outer shell and also make a circular motion, enabling the plastic sample to be in full contact with the digestion solution, improving the digestion reaction rate and the digestion degree of the sample, and achieving the improvement of the accuracy of heavy metal detection.

[0061] In another technical solution, for the pretreatment device for detecting heavy metals in plastic products, the digestion mechanism further includes:

[0062] The first ring 81 is horizontally arranged at the top of the inner shell 3, the center of the first ring 81 is located on the axis of the inner shell 3, and the outer circular edge of the first ring 81 is fixedly connected to the inner wall of the inner shell 3 through a plurality of first connecting rods 82; annular first sliding rails are provided on both the top surface and the bottom surface of the first ring 81;

[0063] The second ring 83 is horizontally and concentrically sleeved inside the first ring 81, and the inner circular edge of the second ring 83 is fixedly connected to the exhaust pipe 5 through a plurality of second connecting rods 84; annular second sliding rails are provided on both the top surface and the bottom surface of the second ring 83;

[0064] A plurality of second sliders 85 are arranged at intervals in the circumferential direction between the first ring 81 and the second ring 83. The top and bottom ends of any one second slider 85 are respectively slidably clamped in the two first sliding rails, and the top and bottom ends of the other end are respectively slidably clamped in the two second sliding rails. A third through hole 851 is provided through the middle of the second slider in the vertical direction;

[0065] A plurality of brush rods 6 are provided, with one brush rod 6 corresponding to one second slider 85. The upper end of any one brush rod 6 is fixedly connected to the bottom of the cover body 4, and the lower end vertically penetrates through the corresponding third through hole 851 and extends into the inner shell 3. Any one brush rod 6 is slidably connected to the corresponding third through hole 851 in the vertical direction, and a brush in contact with the inner wall of the inner shell 3 is provided at the lower end of the brush rod 6.

[0066] The digestion mechanism of the present invention further includes a first ring and a second ring sleeved inside the inner shell from inside to outside in sequence. Preferably, the centers of the first ring and the second ring coincide with the center of the inner circle at the top of the inner shell; the bottom of the exhaust pipe is fixedly connected to the bottom of the inner shell, the first ring is fixedly connected to the inner wall of the inner shell through a plurality of first connecting rods, the second ring is connected to the exhaust pipe through a plurality of second connecting rods, a plurality of sliders are arranged between the first ring and the second ring, the top and bottom of any one slider are respectively slidably connected to the first ring and the second ring, the third through hole in the middle of the slider is located between the first ring and the second ring, and the third through hole does not interfere with the first ring and the second ring. The third through hole is used for the rod body of the brush rod to pass through, so that the up and down movement of the rotation of the exhaust pipe can drive the inner shell to rotate up and down together. At the same time, it will not be interfered by the brush rod. The brush rod is fixedly connected to the cover body and is stationary. When the inner shell rotates up and down, the brush rod can scrape the inner wall of the inner shell, preventing the plastic sample from adhering to the inner wall of the inner shell and blocking the first through hole. At the same time, the scraping of the brush can further agitate the plastic sample, further improving the digestion reaction rate.

[0067] In another technical solution, for the pretreatment device for detecting heavy metals in plastic products, the digestion mechanism further includes an air guide pipe 91. The lower end of the air guide pipe 91 is rotationally and hermetically connected to the exhaust pipe 5 through a connecting pipe 92, and the upper end is communicated with the acid discharge mechanism. The air guide pipe 91 is a corrugated pipe body; the bottom of the connecting pipe 92 is rotationally and hermetically communicated with the other end of the exhaust pipe 5 through a bearing, and the top is hermetically communicated with the lower end of the air guide pipe 91. The upper part of the connecting pipe 92 is connected to the free end of a vertically lifting electric telescopic rod 94 through a third connecting rod 93. The exhaust pipe is communicated with the acid discharge mechanism through the air guide pipe and the connecting pipe. The design that the corrugated pipe body structures of the air guide pipe and the connecting pipe are rotationally and hermetically connected to the exhaust pipe through bearings enables the exhaust pipe to be hermetically communicated with the acid discharge mechanism while also being able to rotate and move up and down, ensuring that the exhaust pipe can rotate and move up and down relative to the acid discharge mechanism while also being able to smoothly discharge the acid gas during the digestion reaction. The electric telescopic rod drives the connecting pipe to move up and down, thereby driving the exhaust pipe to move up and down.

[0068] In another technical solution, for the pretreatment device for detecting heavy metals in plastic products, a regulating valve is provided inside the exhaust pipe, and it includes:

[0069] A regulating pipe 51, which is a hollow frustum structure coaxially sleeved inside the exhaust pipe 5; the regulating pipe 51 is larger at the top and smaller at the bottom;

[0070] A sealing plug 52, which is a conical structure capable of plugging the bottom of the regulating pipe 51;

[0071] A guiding cylinder 53, which is coaxially arranged inside the exhaust pipe 5 and above the sealing plug 52. The top of the guiding cylinder 53 is fixedly connected to the inner wall of the exhaust pipe 5 through a fourth connecting rod 54;

[0072] A movable rod 55, which is coaxially arranged inside the exhaust pipe 5 and between the sealing plug 52 and the guiding cylinder 53. The lower end of the movable rod 55 is fixedly connected to the top of the sealing plug 52, and the upper end is inserted into the inside of the guiding cylinder 53 and connected to the inner top surface of the guiding cylinder 53 through a spring 56; the movable rod 55 is slidably connected to the guiding cylinder 53 in the vertical direction.

[0073] In the above technical solution, a regulating valve is provided inside the exhaust pipe. When the pressure inside the outer shell reaches a certain value (the pressure is greater than the sum of the compression elastic force of the spring and the gravity of the sealing plug and the movable rod), the sealing plug can be pushed upward, the regulating valve is opened, and then the excess acid gas is discharged during the digestion process. While ensuring that the digestion solution is recycled through multiple circulation pipes, the acid gas is discharged to the acid discharge mechanism through the exhaust pipe for consumption, avoiding the situation of excessive pressure inside the outer shell and ensuring the normal and rapid progress of the digestion reaction.

[0074] In another technical solution, for the pretreatment device for detecting heavy metals in plastic products, a sealing gasket is provided around the inner wall of the second through hole, which improves the sealing performance between the exhaust pipe and the second through hole and reduces the amount of acid gas discharged outward.

[0075] In another technical solution, for the pretreatment device for detecting heavy metals in plastic products, the digestion solution supply mechanism includes:

[0076] A digestion solution storage tank 22;

[0077] A pump body 23, whose inlet end is communicated with the digestion solution storage tank through a first liquid guide pipe 24, and whose outlet end is communicated with the inside of the outer shell through a second liquid guide pipe 25. A flow meter is provided on the second liquid guide pipe near the outer shell.

[0078] The pump body is used to transport the digestion solution in the digestion solution storage tank to the inside of the outer shell. By setting the flow meter, the amount of the digestion solution transported to the inside of the outer shell can be determined and controlled according to the amount of the plastic sample.

[0079] In another technical solution, for the pretreatment device for detecting heavy metals in plastic products, the acid discharge mechanism includes:

[0080] A first alkali solution cylinder 71, one side of which is hermetically communicated with the top of the air guide pipe through a first air pipe 73, and the lower end of the first air pipe extends to the bottom of the first alkali solution cylinder;

[0081] A second alkali solution cylinder 72, one side of which is communicated with the other side of the first alkali solution cylinder through a second air pipe 74. One end of the second air pipe is located at the upper part of the first alkali solution cylinder, and the other end extends to the bottom of the second alkali solution cylinder; a third air pipe 75 communicating with the outside is provided on the other side of the second alkali solution cylinder.

[0082] The present invention discloses the specific structure of the acid discharge mechanism. By setting two alkali solution cylinders for two-stage acid consumption, the acid in the acid gas generated by the digestion reaction is consumed as much as possible, ensuring that the gas discharged from the third air pipe meets the quality standard for external discharge and reducing the pollution of the digestion reaction to the air.

[0083] In another technical solution, the pretreatment device for detecting heavy metals in plastic products further includes a cover body 10. The digestion mechanism, the digestion solution supply mechanism and the acid discharge mechanism are all encapsulated in the cover body, and the top surface of the cover body is an openable and closable panel; the free end of the third air pipe extends out of the cover body. Each component of the pretreatment device of the present invention is encapsulated in the cover body. When the device is idle, the top surface of the cover body can be closed to improve the dust-proof performance of the device. When it is necessary to carry out the digestion reaction of the plastic sample, the top surface of the cover body can be opened to perform the operation of the digestion reaction.

[0084] The number of devices and the processing scale described herein are used to simplify the description of the present invention. Applications, modifications, and variations of the present invention will be apparent to those skilled in the art.

[0085] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details and the illustrated examples described herein.

Claims

1. Pretreatment device for detecting heavy metals in plastic products, characterized in that, Comprising: A digestion mechanism, which includes: A heating jacket; An outer shell, which is a hollow cylinder with a spherical bottom structure, and the bottom of the outer shell is located inside the heating jacket; A plurality of circulation pipes, which are arranged at intervals along the circumferential direction outside the outer shell. The lower end of any one circulation pipe communicates with the lower part of the outer shell, and the upper end communicates with the upper part of the outer shell; a check valve is provided at the upper end of any one circulation pipe; An inner shell, which is coaxially sleeved inside the outer shell and has the same structure as the outer shell. A plurality of first through holes are provided on the side wall of the inner shell; the plastic sample to be detected is accommodated inside the inner shell; A cover body, which is used to seal and cover the top of the outer shell. A second through hole is provided in the middle of the cover body, and a first slider is provided on one side wall of the second through hole; a feeding port is provided on the cover body, and a baffle for opening and closing is provided inside; An exhaust pipe, one end of which is located inside the inner shell, and the other end vertically passes through the second through hole and extends above the cover body. A spiral groove is provided on the circumferential outer wall of the exhaust pipe in the vertical direction, and the first slider is slidably arranged in the spiral groove; the exhaust pipe is fixedly connected to the inner shell, and a plurality of exhaust holes are provided at intervals on the exhaust pipe; A first ring, which is horizontally arranged on the top of the inner shell, and the center of the first ring is located on the axis of the inner shell. The outer circular edge of the first ring is fixedly connected to the inner wall of the inner shell through a plurality of first connecting rods; annular first sliding rails are provided on the top and bottom surfaces of the first ring; A second ring, which is horizontally and concentrically sleeved inside the first ring. The inner circular edge of the second ring is fixedly connected to the exhaust pipe through a plurality of second connecting rods; annular second sliding rails are provided on the top and bottom surfaces of the second ring; A plurality of second sliders, which are arranged at intervals along the circumferential direction between the first ring and the second ring. One end of any one second slider is slidably clamped at the top and bottom in two first sliding rails respectively, and the other end is slidably clamped at the top and bottom in two second sliding rails respectively. A third through hole is vertically penetrated through the middle of the second slider; A plurality of brush rods, one brush rod is correspondingly arranged for one second slider. The upper end of any one brush rod is fixedly connected to the bottom of the cover body, and the lower end vertically passes through the corresponding third through hole and extends into the inner shell. Any one brush rod is slidably connected to the corresponding third through hole in the vertical direction, and bristles in contact with the inner wall of the inner shell are provided at the lower end of the brush rod; A gas guide pipe, the lower end of which is rotationally and sealingly connected to the exhaust pipe through a connecting pipe, and the upper end is communicated with an acid discharge mechanism. The gas guide pipe is a corrugated pipe body; the bottom of the connecting pipe is rotationally and sealingly communicated with the other end of the exhaust pipe through a bearing, and the top is sealingly communicated with the lower end of the gas guide pipe. The upper part of the connecting pipe is connected to the free end of a vertically lifting electric telescopic rod through a third connecting rod; A digestion liquid supply mechanism, which is communicated with the inside of the outer shell; A regulating valve is provided inside the exhaust pipe, which includes: A regulating pipe, which is a hollow frustum structure coaxially sleeved inside the exhaust pipe; the regulating pipe is larger at the top and smaller at the bottom; A plugging block, which is a conical structure capable of plugging the bottom of the adjusting pipe; A guiding cylinder, which is coaxially arranged inside the exhaust pipe and above the plugging block, and the top of the guiding cylinder is fixedly connected to the inner wall of the exhaust pipe through a fourth connecting rod; A movable rod, which is coaxially arranged inside the exhaust pipe and between the plugging block and the guiding cylinder. The lower end of the movable rod is fixedly connected to the top of the plugging block, and the upper end is inserted into the guiding cylinder and connected to the inner top surface of the guiding cylinder through a spring; the movable rod is slidably connected to the guiding cylinder in the vertical direction.

2. The pretreatment device for detecting heavy metals in plastic products according to claim 1, characterized in that, The acid discharging mechanism includes: A first lye cylinder, one side of which is hermetically communicated with the top of the guiding pipe through a first air pipe, and the lower end of the first air pipe extends to the bottom of the first lye cylinder; A second lye cylinder, one side of which is communicated with the other side of the first lye cylinder through a second air pipe. One end of the second air pipe is located in the upper part of the first lye cylinder, and the other end extends to the bottom of the second lye cylinder; a third air pipe communicating with the outside is arranged on the other side of the second lye cylinder; A sealing gasket is annularly arranged on the inner wall of the second through hole.

3. The pretreatment device for detecting heavy metals in plastic products according to claim 2, characterized in that, The digestion solution supply mechanism includes: A digestion solution storage tank; A pump body, the inlet end of which is communicated with the digestion solution storage tank through a first liquid guide pipe, and the outlet end is communicated with the inside of the outer shell through a second liquid guide pipe. A flow meter is arranged on the second liquid guide pipe near the outer shell.

4. The pretreatment device for detecting heavy metals in plastic products according to claim 2, wherein, It further includes a cover body. The digestion mechanism, the digestion solution supply mechanism and the acid discharging mechanism are all encapsulated in the cover body. The top surface of the cover body is an openable and closable panel; the free end of the third air pipe extends out of the cover body.

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