Method and device for testing content of substances in polyacrylonitrile carbon fiber production recovery liquid

Abstract

The present disclosure provides a test method for the content of substances in polyacrylonitrile carbon fiber production recovery liquid, which comprises: obtaining the polyacrylonitrile carbon fiber production recovery liquid and placing it in a near-infrared spectrometer for detection to obtain spectral information of the polyacrylonitrile carbon fiber production recovery liquid; the spectral information comprises spectral information of preset components; according to the mapping relationship between the spectral information and the spectral information of the preset components and the content of the preset components, the content of the preset components in the polyacrylonitrile carbon fiber production recovery liquid is determined. The test method is simple to operate, and can be applied to the test of the content of substances in the production recovery liquid generated in the large-scale industrial production of polyacrylonitrile carbon fiber, and can meet the high-frequency and high-efficiency detection requirements in large-scale industrial production, and provide guidance for the recycling of production recovery liquid.

Description

Technical Field

[0001] This disclosure relates to the field of substance detection, specifically to a method and apparatus for testing the substance content in a polyacrylonitrile carbon fiber production recycled liquid. Background Technology

[0002] Carbon fiber is widely used in many fields due to its high performance. The production of carbon fiber involves the extensive use of dimethyl sulfoxide (DMSO) solution. The resulting DMSO wastewater has a high concentration of DMSO and cannot be directly discharged; it must be recycled to reduce raw material costs in the production process. However, directly reusing the DMSO wastewater in production will affect the quality of the carbon fiber product. Therefore, with the demands of large-scale production, it is necessary to quickly and accurately detect the content of key substances in the recycled polyacrylonitrile carbon fiber production liquid in order to control the content of these substances. Summary of the Invention

[0003] The purpose of this disclosure is to overcome the above-mentioned deficiencies in the prior art and to provide a method and apparatus for testing the content of substances in the recycled liquid from the production of polyacrylonitrile carbon fiber.

[0004] A first aspect of the exemplary embodiments of this disclosure provides a method for testing the content of substances in a polyacrylonitrile carbon fiber production recycled liquid, comprising:

[0005] The polyacrylonitrile carbon fiber production recovery liquid was obtained and placed in a near-infrared spectrometer for detection to obtain the spectral information of the polyacrylonitrile carbon fiber production recovery liquid; the spectral information includes the spectral information of preset components;

[0006] The content of the preset component in the polyacrylonitrile carbon fiber production recycled liquid is determined based on the mapping relationship between the spectral information and the spectral information and content of the preset component.

[0007] In some exemplary embodiments, the preset components include one or more of dimethyl sulfoxide, acrylonitrile, and water.

[0008] In some exemplary embodiments, the testing method further includes:

[0009] A predetermined number of sample solutions containing the predetermined component are placed in a near-infrared spectrometer for detection to obtain the spectral information of the predetermined component; the content of the predetermined component in each of the predetermined number of sample solutions is different;

[0010] The mapping relationship between the spectral information and the content of the preset component is determined based on the spectral information and the content of the preset component in the sample solution of the preset number of portions.

[0011] In some exemplary embodiments, the preset components include dimethyl sulfoxide, acrylonitrile, and water;

[0012] Before placing a predetermined number of sample solutions of the predetermined component into a near-infrared spectrometer for detection, the test method further includes:

[0013] The dimethyl sulfoxide reagent and acrylonitrile reagent are dehydrated, and the dehydrated dimethyl sulfoxide reagent, acrylonitrile reagent, and deionized water are used to prepare the sample solution containing a predetermined amount of dimethyl sulfoxide, acrylonitrile, and water.

[0014] In some exemplary embodiments, the preset content includes: 65-95% by weight of dimethyl sulfoxide, 5-30% by weight of acrylonitrile, and 0-5% by weight of water.

[0015] In some exemplary embodiments, the dehydration of the dimethyl sulfoxide reagent and acrylonitrile reagent includes:

[0016] The molecular sieve was immersed in the dimethyl sulfoxide reagent and the acrylonitrile reagent for more than 30 minutes respectively, and then the molecular sieve was filtered out.

[0017] In some exemplary embodiments, the preset number of portions is greater than or equal to 20.

[0018] In some exemplary embodiments, determining the mapping relationship between the spectral information and content of the preset component based on the spectral information and content of the preset component in the preset number of sample solutions includes:

[0019] The mapping relationship between the spectral information and content of the preset component in the preset number of portions is determined by analyzing the spectral information and content using a least squares model.

[0020] In some exemplary embodiments, the range of the preset content covers the range of preset components in the polyacrylonitrile carbon fiber production recycled liquid.

[0021] A second aspect of the exemplary embodiments of this disclosure provides a testing device for the content of substances in a polyacrylonitrile carbon fiber production recycled liquid, the testing device being used to implement the above-described testing method for the content of substances in a polyacrylonitrile carbon fiber production recycled liquid.

[0022] The testing apparatus includes:

[0023] A near-infrared spectrometer is used to acquire spectral information of preset components in the polyacrylonitrile carbon fiber production recovery liquid;

[0024] A data processing device is connected to the near-infrared spectrometer for determining the content of the preset component based on the mapping relationship between the spectral information and the spectral information and content of the preset component.

[0025] A data acquisition device is used to acquire the recycled liquid from the production of polyacrylonitrile carbon fiber. The data acquisition device is connected to the signal of the near-infrared spectrometer, and the data acquisition device is connected to the test vessel of the near-infrared spectrometer through a pipeline.

[0026] The beneficial effects of this disclosure include, but are not limited to: the test method for the content of substances in the production recovery liquid of polyacrylonitrile carbon fiber provided by this disclosure is simple to operate and can be applied to the test of the content of substances in the production recovery liquid generated in the large-scale industrial production of polyacrylonitrile carbon fiber. It can meet the high-frequency and high-efficiency detection needs in large-scale industrial production and provide guidance for the recycling and reuse of production recovery liquid.

[0027] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of a method for testing the content of substances in a recycled liquid from the production of polyacrylonitrile carbon fiber, which is an exemplary embodiment of this disclosure.

[0030] Figure 2 The test method, which is an exemplary embodiment of this disclosure, also includes a flowchart;

[0031] Figure 3 The test method, which is an exemplary embodiment of this disclosure, further includes a flowchart before placing a preset number of sample solutions of preset components in a near-infrared spectrometer for detection.

[0032] Figure 4 This is a schematic diagram showing the relationship between the predicted and actual values ​​of the weight percentage of dimethyl sulfoxide in an exemplary embodiment of this disclosure.

[0033] Figure 5 This is a schematic diagram showing the relationship between the predicted and actual values ​​of acrylonitrile weight percentage in an exemplary embodiment of this disclosure.

[0034] Figure 6This is a schematic diagram showing the relationship between the predicted and actual values ​​of the water weight percentage in an exemplary embodiment of this disclosure.

[0035] Figure 7 This is a schematic diagram of a testing apparatus for the content of substances in a polyacrylonitrile carbon fiber production recycled liquid, which is an exemplary embodiment of this disclosure.

[0036] Figure 8 A schematic diagram of the specific structure of a probe according to an exemplary embodiment of this disclosure;

[0037] Figure 9 This is a schematic diagram of a laboratory testing apparatus according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0038] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the protection scope of this disclosure.

[0039] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this disclosure. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0040] In related technologies, acrylonitrile content is tested by titration and dimethyl sulfoxide content is tested by Abbe light-shielding instrument. However, these detection methods are inefficient and cannot meet the high-frequency and high-efficiency detection requirements of large-scale industrial production.

[0041] This exemplary embodiment provides a method for testing the content of substances in a recycled liquid from the production of polyacrylonitrile carbon fiber, such as... Figure 1 As shown, the test method includes:

[0042] S100: Obtain the polyacrylonitrile carbon fiber production recovery liquid and place it in a near-infrared spectrometer for detection to obtain the spectral information of the polyacrylonitrile carbon fiber production recovery liquid; the spectral information includes the spectral information of preset components.

[0043] The method for testing the substance content in the recycled liquid from the production of polyacrylonitrile carbon fiber provided in this exemplary embodiment is applicable to the detection of substance content in the recycled liquid generated during the large-scale industrial production of polyacrylonitrile carbon fiber, so as to recycle and utilize the substances in the recycled liquid generated during the large-scale industrial production of polyacrylonitrile carbon fiber. Therefore, the recycled liquid from the production of polyacrylonitrile carbon fiber is obtained as the test solution. Near-infrared light is an electromagnetic wave between visible light (VIS) and mid-infrared light (MIR), and the wavelength range of the near-infrared spectral region is 780–2526 nm (12820–3959 cm⁻¹). -1 The near-infrared spectral region coincides with the absorption regions of the combination frequencies and overtones of the vibrations of hydrogen-containing groups (OH, NH, CH) in organic molecules. By scanning the near-infrared spectrum of the test solution with a near-infrared spectrometer, characteristic information of the hydrogen-containing groups in the organic molecules of the test solution can be obtained. The obtained polyacrylonitrile carbon fiber production recovery liquid was used as the test solution and placed in a near-infrared spectrometer for detection. The spectral information of the polyacrylonitrile carbon fiber production recovery liquid, a mixture containing multiple components, was obtained. The spectral information included the spectral information of a preset component, which is the component that needs to be detected and recovered.

[0044] In the exemplary embodiments provided in this disclosure, the preset components include one or more of dimethyl sulfoxide, acrylonitrile, and water. Dimethyl sulfoxide and acrylonitrile are the two main raw materials for producing polyacrylonitrile carbon fiber, and they need to be added in large quantities during production. Therefore, the polyacrylonitrile carbon fiber production recovery liquid mainly contains dimethyl sulfoxide and acrylonitrile, and may also include a small amount of water introduced during the production process. Therefore, dimethyl sulfoxide, acrylonitrile, and water are used as preset components, and the dimethyl sulfoxide, acrylonitrile, and water in the polyacrylonitrile carbon fiber production recovery liquid are tested for subsequent recovery.

[0045] S200: Determine the content of the preset components in the polyacrylonitrile carbon fiber production recovery liquid based on the mapping relationship between the spectral information and the spectral information and content of the preset components.

[0046] Based on the established mapping relationship between the spectral information and content of the preset components, and the spectral information of the polyacrylonitrile carbon fiber production recovery liquid obtained in step S100, the content of the preset components in the tested polyacrylonitrile carbon fiber production recovery liquid can be quickly determined. The content can be a characterizing ratio of the preset components in the polyacrylonitrile carbon fiber production recovery liquid, such as a mass percentage or volume percentage.

[0047] The method for testing the substance content in the production recovery liquid of polyacrylonitrile carbon fiber provided by the exemplary embodiments of this disclosure is simple to operate and can be applied to the testing of substance content in the production recovery liquid generated in the large-scale industrial production of polyacrylonitrile carbon fiber. It can meet the high-frequency and high-efficiency detection needs in large-scale industrial production and provide guidance for the recycling and reuse of production recovery liquid.

[0048] In the exemplary embodiments provided in this disclosure, such as Figure 2 As shown, the test method also includes:

[0049] S101: Place a preset number of sample solutions containing preset components into a near-infrared spectrometer for detection to obtain the spectral information of the preset components; the content of the preset components in each of the preset number of sample solutions is different.

[0050] Before detecting the recycled polyacrylonitrile carbon fiber production liquid in a near-infrared spectrometer, it is necessary to establish a mapping relationship between the spectral information of the preset components and their contents. Therefore, a preset number of sample solutions containing the preset components, such as a preset number of sample solutions containing dimethyl sulfoxide, acrylonitrile, and water, are first detected in the near-infrared spectrometer. The contents of the preset components in these sample solutions are different, and the contents of the preset components in each sample solution are correlated and representative. For example, the contents of each preset component in each sample solution increase or decrease in a certain proportion. This makes the established mapping relationship more accurate and applicable.

[0051] S102: Determine the mapping relationship between the spectral information and content of the preset components based on the spectral information and content of the preset components in the sample solutions of the preset number of samples.

[0052] Based on the spectral information of each preset component in a preset number of sample solutions and the content of each preset component in each sample solution, a mapping relationship between the spectral information and the content of the preset components can be obtained. This mapping relationship can be used to determine the content of preset components in the recycled liquid from the production of polyacrylonitrile carbon fiber.

[0053] In the exemplary embodiments provided in this disclosure, the preset number of sample solutions is greater than or equal to 20. More than 20 sample solutions containing preset components are sequentially placed in a near-infrared spectrometer for detection. The content of the preset component in these 20 or more sample solutions is different, and the content of the preset component in each sample solution is correlated and representative. This allows for the establishment of a more accurate mapping relationship, avoiding inaccurate or inapplicable mapping relationships due to an insufficient number of sample solutions. The preset number of sample solutions can be less than or equal to 50 to ensure accurate determination of the mapping relationship between the spectral information and content of the preset component without increasing testing costs and improving testing efficiency.

[0054] In the exemplary embodiments provided in this disclosure, when the preset components include dimethyl sulfoxide, acrylonitrile, and water; before placing a sample solution of the preset components in a preset number of portions for detection in a near-infrared spectrometer, as... Figure 3 As shown, the test method also includes:

[0055] S1001: Dehydrate dimethyl sulfoxide reagent and acrylonitrile reagent;

[0056] S1002: A sample solution containing predetermined amounts of dimethyl sulfoxide, acrylonitrile, and water is prepared using dehydrated dimethyl sulfoxide reagent, acrylonitrile reagent, and deionized water.

[0057] In the exemplary example of this disclosure, in order to establish the mapping relationship between the spectral information of a preset component and the content of the preset component, it is necessary to prepare a preset number of sample solutions. When the preset components include dimethyl sulfoxide, acrylonitrile, and water, the method for preparing the sample solution is as follows: The dimethyl sulfoxide reagent and acrylonitrile reagent are dehydrated. Using the dehydrated dimethyl sulfoxide reagent and acrylonitrile reagent, i.e., pure dimethyl sulfoxide reagent and pure acrylonitrile reagent, a sample solution containing a preset number of dimethyl sulfoxide, acrylonitrile, and water is prepared with deionized water. The sample solution is prepared using pure reagents, and... Accurate weighing (to ±0.0001g) and thorough mixing allow for precise control of the preset contents of dimethyl sulfoxide, acrylonitrile, and water in each sample solution. For example, controlling the preset contents of dimethyl sulfoxide, acrylonitrile, and water in each sample solution to be relevant and representative can establish a more accurate mapping relationship. This avoids errors in the preset contents of dimethyl sulfoxide, acrylonitrile, and water in the prepared sample solution due to impurities in the reagents, and thus avoids the problem of inaccurate mapping relationship between the spectral information and contents of dimethyl sulfoxide, acrylonitrile, and water.

[0058] In the exemplary embodiments provided in this disclosure, the dehydration of dimethyl sulfoxide reagent and acrylonitrile reagent includes: soaking the molecular sieve in dimethyl sulfoxide reagent and acrylonitrile reagent for more than 30 minutes respectively, and then filtering the molecular sieve to remove the water.

[0059] Molecular sieves are aluminosilicates, mainly composed of silica and aluminum connected by oxygen bridges to form a spacious framework structure. The structure contains many channels with uniform pore size and neatly arranged cavities with a large internal surface area. After immersing the molecular sieve in dimethyl sulfoxide (DMSO) and acrylonitrile (AC) reagents for more than 30 minutes, the molecular sieve can completely adsorb the water mixed in the DMSO and AC reagents. Subsequently, the molecular sieve is removed by filtration to obtain pure DMSO and AC reagents.

[0060] In the exemplary embodiments provided in this disclosure, the range of preset content covers the range of preset components in the polyacrylonitrile carbon fiber production recycled liquid.

[0061] To test the content of dimethyl sulfoxide (DMSO), acrylonitrile, and water in the polyacrylonitrile (PAC) carbon fiber production recovery liquid, a predetermined number of sample solutions are prepared. These solutions are prepared using dehydrated DMC reagent, acrylonitrile reagent, and deionized water, and contain the predetermined amounts of DMC, acrylonitrile, and water. Then, a mapping relationship between the spectral information and the content of DMC, acrylonitrile, and water is established using these predetermined number of sample solutions. The predetermined content range of DMC, acrylonitrile, and water in the prepared sample solutions should cover the content range of DMC, acrylonitrile, and water in the PAC carbon fiber production recovery liquid. This ensures that the predetermined content of DMC, acrylonitrile, and water in the prepared sample solutions is as close as possible to and mimics the content range of DMC, acrylonitrile, and water in the PAC carbon fiber production recovery liquid. The established mapping relationship between the spectral information and the content of DMC, acrylonitrile, and water in the prepared sample solutions can improve the accuracy of the test results when subsequently determining the content of DMC, acrylonitrile, and water in the PAC carbon fiber production recovery liquid.

[0062] In the exemplary embodiments provided in this disclosure, the content is taken as a weight percentage, and the preset content may include: 65-95% by weight of dimethyl sulfoxide, 5-30% by weight of acrylonitrile, and 0-5% by weight of water.

[0063] Based on the approximate range of dimethyl sulfoxide, acrylonitrile, and water content in the polyacrylonitrile carbon fiber production recovery liquid, the preset content in the sample solution is limited to: 65-95% by weight of dimethyl sulfoxide, 5-30% by weight of acrylonitrile, and 0-5% by weight of water. This can approximate and mimic the content range of dimethyl sulfoxide, acrylonitrile, and water in the polyacrylonitrile carbon fiber production recovery liquid.

[0064] In the exemplary embodiments provided in this disclosure, determining the mapping relationship between the spectral information and content of a preset component based on the spectral information and content of a preset component in a preset number of portions includes: analyzing the spectral information and content of the preset component in a preset number of sample solutions using a least squares model to determine the mapping relationship between the spectral information and content of the preset component.

[0065] A predetermined number of sample solutions containing predetermined components are placed in a near-infrared spectrometer for detection. Each sample solution can be scanned twice or more using the near-infrared spectrometer, and the spectra are saved to obtain the spectral information of the predetermined components. Based on the spectral information of the predetermined components in the predetermined number of sample solutions and the content of the predetermined components in each sample solution, the least squares model is used to analyze and determine the mapping relationship between the spectral information and the content of the predetermined components. In one embodiment, the goodness of fit R for dimethyl sulfoxide, acrylonitrile, and water in the obtained mapping relationship is... 2 The percentages were 99.96%, 99.81%, and 99.47%, respectively. Through re-preparation and verification, the predicted and actual values ​​of dimethyl sulfoxide, acrylonitrile, and water in the prepared solution, determined by the established mapping relationship, were obtained as follows: Figure 4 , Figure 5 , Figure 6 As shown, Figure 4 , Figure 5 , Figure 6 The x-axis represents the actual dimethyl sulfoxide concentration in the prepared solution (…). Figure 4 ), Acrylonitrile ( Figure 5 ) and water ( Figure 6 The content of ) is shown on the horizontal axis, and the vertical axis represents the predicted value determined by the near-infrared spectrometer based on the mapping relationship. The closer the correlation coefficient of the horizontal and vertical axes is to 1, the more consistent the predicted value of the near-infrared spectrometer is with the standard value, and the higher the accuracy.

[0066] In the exemplary embodiments provided in this disclosure, after determining the content of the preset components in the polyacrylonitrile carbon fiber production recovery liquid, the testing method further includes: optimizing the spectrum of the polyacrylonitrile carbon fiber production recovery liquid, removing abnormal spectra, performing quantitative correction through the optimization function of a near-infrared spectrometer, and optimizing the mapping relationship between the spectral information and weight percentage of the preset components.

[0067] In the exemplary embodiments provided in this disclosure, after obtaining the mapping relationship between the spectral information and weight percentage of the preset components, the testing method further includes: optimizing the spectrum of each sample solution, removing abnormal spectra, performing quantitative correction through the optimization function of the near-infrared spectrometer, and optimizing the mapping relationship between the spectral information and weight percentage of the preset components.

[0068] In the exemplary embodiments provided in this disclosure, abnormal spectra include spectra with indistinct absorption peaks, or spectra with severe spectral shifts or drifts.

[0069] After the above model optimization, the mapping relationship between the spectral information and weight percentage of the preset components can be continuously optimized and quantitatively corrected after establishing the mapping relationship between the spectral information and weight percentage of the preset components and after testing the weight percentage of the preset components in the polyacrylonitrile carbon fiber production recovery liquid, so that the established mapping relationship is more accurate.

[0070] An exemplary embodiment of this disclosure provides a testing apparatus for the content of substances in a recycled liquid from the production of polyacrylonitrile carbon fiber. This testing apparatus is used to implement the aforementioned method for testing the content of substances in a recycled liquid from the production of polyacrylonitrile carbon fiber. Figure 7 As shown, the testing device 100 includes: a near-infrared spectrometer 20, a data processing device 30, and a data acquisition device 10. The near-infrared spectrometer 20 is used to acquire the spectral information of a preset component in the polyacrylonitrile carbon fiber production recovery liquid, and can also be used to acquire the spectral information of a sample solution containing the preset component. The data processing device 30 is connected to the near-infrared spectrometer 20 and is used to determine the mapping relationship between the spectral information of the preset component and the content of the preset component, and to determine the content of the preset component based on the mapping relationship between the spectral information and the content of the preset component. The data acquisition device 10 is used to acquire the polyacrylonitrile carbon fiber production recovery liquid in the recovery tower 40. For example, the data acquisition device 10 can be a probe installed at the outlet of the recovery tower, for reference... Figure 8 The diagram shows the specific structure of probe 60. The probe can be fixed at the outlet of the recovery tower. The inlet 80 at the bottom of the probe is connected to the outlet of the recovery tower. The polyacrylonitrile carbon fiber production recovery liquid enters probe 60 through inlet 80 and is then transmitted to the test dish of near-infrared spectrometer 20 through outlet 70. Acquisition device 10 is signal-connected to near-infrared spectrometer 20, and acquisition device 10 is connected to the test dish of near-infrared spectrometer 20. Figure 7 (Not shown in the image) Connected via pipe 50, the near-infrared spectrometer 20 can transmit signals to the acquisition device 10, control the acquisition device 10 to take samples, and transfer the obtained polyacrylonitrile carbon fiber production recovery liquid to the test vessel of the near-infrared spectrometer 20 through pipe 50, and test the content of substances in the polyacrylonitrile carbon fiber production recovery liquid.

[0071] The method for testing the content of substances in the recycled liquid from the production of polyacrylonitrile carbon fiber, implemented by the aforementioned testing device, is simple to operate and suitable for testing the content of substances in the recycled liquid generated in the large-scale industrial production of polyacrylonitrile carbon fiber. It can perform sampling at any time, so the testing device can meet the high-frequency and high-efficiency detection needs in large-scale industrial production and provide guidance for the recycling and reuse of the recycled liquid.

[0072] To more clearly explain the technical solution of this disclosure, a specific example is given according to the test method for the content of substances in the recycled liquid from the production of polyacrylonitrile carbon fiber, which is an example of this disclosure.

[0073] Example 1

[0074] Prepare four test solutions (a, b, c, and d) as follows, with the component content of each solution as follows:

[0075] a. 84.02% dimethyl sulfoxide, 14.97% acrylonitrile, 1.02% water;

[0076] b. 69.89% dimethyl sulfoxide, 29.07% acrylonitrile, 1.08% water;

[0077] c. 94.85% dimethyl sulfoxide, 5.06% acrylonitrile, 0.09% water;

[0078] d. 84.02% dimethyl sulfoxide, 11.05% acrylonitrile, 4.93% water.

[0079] The method for testing the substance content in the polyacrylonitrile carbon fiber production recycled liquid provided by the above exemplary embodiments of this application, and as such Figure 9 The laboratory testing apparatus 200 shown includes a first glass dish 202, a second glass dish 207, a near-infrared spectrometer 205, and a computer 206. A solution storage tank 201 adds the solution to be tested to the first glass dish 202. The first glass dish 202 is used to simulate the recovery tower of polyacrylonitrile carbon fiber production recovery liquid. The second glass dish 207 is connected to the first glass dish 202 via a U-tube 203 to simulate the flow state of the polyacrylonitrile carbon fiber production recovery liquid. A probe 204 is inserted into the second glass dish 207 to collect samples of the solution to be tested. The probe 204 is connected to the near-infrared spectrometer 205 via both signal and piping connections. The solution collected by the probe 204 is transported to the testing vessel of the near-infrared spectrometer 205 for testing. The computer 206 is connected to the near-infrared spectrometer 205 via signal connection to determine the weight percentages of dimethyl sulfoxide, acrylonitrile, and water in the solution to be tested.

[0080] The acrylonitrile content, dimethyl sulfoxide content, and water content in the four test solutions (a, b, c, and d) measured by the above method and apparatus are as follows:

[0081] a. Dimethyl sulfoxide content: 84.01%, acrylonitrile content: 14.95%, water content: 1.04%;

[0082] b. Dimethyl sulfoxide content: 69.93%, acrylonitrile content: 29.02%, water content: 1.05%;

[0083] c. Dimethyl sulfoxide content: 94.82%, acrylonitrile content: 5.08%, water content: 0.10%;

[0084] d. Dimethyl sulfoxide content: 84.03%, acrylonitrile content: 11.02%, water content: 4.95%.

[0085] As can be seen from the above test results, the test method for the content of substances in the polyacrylonitrile carbon fiber production recovery liquid of this disclosure can accurately test the weight percentage of the preset components in the test solution, and the error of the test results is small, which can provide guidance for the recycling and reuse of polyacrylonitrile carbon fiber production recovery liquid.

[0086] Example 2

[0087] Prepare the test solution with the following components: 84.02% dimethyl sulfoxide, 14.97% acrylonitrile, and 1.02% water. Utilize... Figure 9 The laboratory testing device 200 shown in the figure simulates online testing, automatically sampling every 5 minutes. The test results are shown in Table 1.

[0088] Table 1

[0089]

[0090]

[0091] As can be seen from the data in Table 1, the exemplary test method for the content of substances in the recycled liquid from the production of polyacrylonitrile carbon fiber of this disclosure can sample the test solution at regular intervals and continuously and accurately test the weight percentage of preset components in the test solution.

[0092] Comparative Example 1

[0093] Sample solutions were prepared and a mapping relationship was established using undried laboratory-grade dimethyl sulfoxide and acrylonitrile.

[0094] The above-prepared solution (84.02% dimethyl sulfoxide, 14.97% acrylonitrile, 1.02% water) was used for verification. Sampling was performed using a probe, and testing was conducted using a near-infrared spectroscopy. The final measured results for acrylonitrile content, dimethyl sulfoxide content, and water content are as follows:

[0095] Acrylonitrile content: 79.49%, dimethyl sulfoxide content: 18.34%, water content: 2.17%.

[0096] Comparative Example 2

[0097] After removing water from dimethyl sulfoxide and acrylonitrile using molecular sieves for 20 min, sample solutions were prepared and a mapping relationship was established.

[0098] The above-prepared solution (84.02% dimethyl sulfoxide, 14.97% acrylonitrile, 1.02% water) was used for verification. Sampling was performed using a probe, and testing was conducted using a near-infrared spectroscopy. The final measured results for acrylonitrile content, dimethyl sulfoxide content, and water content are as follows:

[0099] Acrylonitrile content: 80.12%, dimethyl sulfoxide content: 16.23%, water content: 3.65%.

[0100] The data from Comparative Example 1 and Comparative Example 2 show that without using molecular sieves to dry dimethyl sulfoxide and acrylonitrile, or using molecular sieves to remove water from dimethyl sulfoxide and acrylonitrile within 30 minutes, the preparation of the sample solution and the establishment of the mapping relationship are not accurate enough for testing the substance content in the polyacrylonitrile carbon fiber production recovery liquid.

[0101] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A method for testing the content of substances in a recycled liquid from the production of polyacrylonitrile carbon fiber, characterized in that, include: The polyacrylonitrile carbon fiber production recovery liquid was obtained and placed in a near-infrared spectrometer for detection to obtain the spectral information of the polyacrylonitrile carbon fiber production recovery liquid; The spectral information includes the spectral information of preset components; The content of the preset component in the polyacrylonitrile carbon fiber production recovery liquid is determined based on the mapping relationship between the spectral information and the spectral information and content of the preset component. The preset components include dimethyl sulfoxide, acrylonitrile, and water; The testing method also includes: A predetermined number of sample solutions containing the predetermined component are placed in a near-infrared spectrometer for detection to obtain the spectral information of the predetermined component; the content of the predetermined component in each of the predetermined number of sample solutions is different; The mapping relationship between the spectral information and the content of the preset component is determined based on the spectral information and the content of the preset component in the sample solution of the preset number of portions; Before placing a predetermined number of sample solutions containing the predetermined components into a near-infrared spectrometer for detection, the test method further includes: The dimethyl sulfoxide reagent and acrylonitrile reagent are dehydrated, and the dehydrated dimethyl sulfoxide reagent, acrylonitrile reagent and deionized water are used to prepare the sample solution containing the dimethyl sulfoxide, acrylonitrile and water in a predetermined amount; The process of removing water from dimethyl sulfoxide reagent and acrylonitrile reagent includes: The molecular sieve was immersed in the dimethyl sulfoxide reagent and the acrylonitrile reagent for more than 30 minutes respectively, and then the molecular sieve was filtered out.

2. The method for testing the substance content in the polyacrylonitrile carbon fiber production recycled liquid according to claim 1, characterized in that, The preset content includes: 65-95% by weight of dimethyl sulfoxide, 5-30% by weight of acrylonitrile, and 0-5% by weight of water.

3. The method for testing the substance content in the polyacrylonitrile carbon fiber production recycled liquid according to claim 1, characterized in that, The preset number of portions is greater than or equal to 20.

4. The method for testing the substance content in the polyacrylonitrile carbon fiber production recycled liquid according to claim 1, characterized in that, Determining the mapping relationship between the spectral information and content of the preset component based on the spectral information and content of the preset component in the sample solution of the preset number of portions includes: The mapping relationship between the spectral information and content of the preset component in the preset number of portions is determined by analyzing the spectral information and content using a least squares model.

5. The method for testing the substance content in the polyacrylonitrile carbon fiber production recycled liquid according to claim 2, characterized in that, The range of preset content covers the range of preset component content in the polyacrylonitrile carbon fiber production recovery liquid.

6. A testing device for the content of substances in the recycled liquid from the production of polyacrylonitrile carbon fiber, characterized in that, The testing device is used to implement the method for testing the content of substances in the polyacrylonitrile carbon fiber production recycled liquid according to any one of claims 1-5; The testing apparatus includes: A near-infrared spectrometer is used to acquire spectral information of preset components in the polyacrylonitrile carbon fiber production recovery liquid; A data processing device is connected to the near-infrared spectrometer for determining the content of the preset component based on the mapping relationship between the spectral information and the spectral information and content of the preset component. A data acquisition device is used to acquire the recycled liquid from the production of polyacrylonitrile carbon fiber. The data acquisition device is connected to the signal of the near-infrared spectrometer, and the data acquisition device is connected to the test vessel of the near-infrared spectrometer through a pipeline.

Images