CN116735523A - Detection method for component content of polyacrylonitrile-based carbon fiber production recovery liquid - Google Patents
Detection method for component content of polyacrylonitrile-based carbon fiber production recovery liquid Download PDFInfo
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- 238000011084 recovery Methods 0.000 title claims abstract description 75
- 229920000049 Carbon (fiber) Polymers 0.000 title claims abstract description 74
- 239000004917 carbon fiber Substances 0.000 title claims abstract description 74
- 239000007788 liquid Substances 0.000 title claims abstract description 74
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 72
- 229920002239 polyacrylonitrile Polymers 0.000 title claims abstract description 59
- 238000007380 fibre production Methods 0.000 title claims abstract description 50
- 238000001514 detection method Methods 0.000 title claims abstract description 28
- ZNNZYHKDIALBAK-UHFFFAOYSA-M potassium thiocyanate Chemical compound [K+].[S-]C#N ZNNZYHKDIALBAK-UHFFFAOYSA-M 0.000 claims abstract description 111
- 229940116357 potassium thiocyanate Drugs 0.000 claims abstract description 111
- 238000010521 absorption reaction Methods 0.000 claims abstract description 81
- 239000012086 standard solution Substances 0.000 claims abstract description 63
- 238000000034 method Methods 0.000 claims abstract description 52
- 239000011259 mixed solution Substances 0.000 claims abstract description 46
- 238000000862 absorption spectrum Methods 0.000 claims abstract description 20
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 191
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 claims description 95
- 239000000243 solution Substances 0.000 claims description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- 238000002329 infrared spectrum Methods 0.000 claims description 13
- 239000000126 substance Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 abstract description 40
- 238000002835 absorbance Methods 0.000 description 22
- 230000000052 comparative effect Effects 0.000 description 10
- 238000012360 testing method Methods 0.000 description 10
- 238000012795 verification Methods 0.000 description 7
- 239000002904 solvent Substances 0.000 description 4
- 238000004448 titration Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000004817 gas chromatography Methods 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000000379 polymerizing effect Effects 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000012085 test solution Substances 0.000 description 2
- YLZOPXRUQYQQID-UHFFFAOYSA-N 3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]propan-1-one Chemical compound N1N=NC=2CN(CCC=21)CCC(=O)N1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F YLZOPXRUQYQQID-UHFFFAOYSA-N 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- -1 polypropylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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- G01N21/3577—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing liquids, e.g. polluted water
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N2001/2893—Preparing calibration standards
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Abstract
The application relates to a method for detecting the component content of a recovery liquid in the production of polyacrylonitrile-based carbon fibers, which comprises the following steps: mixing potassium thiocyanate with the standard solution according to a preset mass ratio to obtain a series of mixed standard solutions; recording infrared absorption spectrograms of the series of mixed standard solutions; calculating the peak height ratio and the mass ratio of each component of the series of mixed standard solutions to potassium thiocyanate according to the infrared absorption spectrum chart, and drawing a standard working curve; mixing a polyacrylonitrile-based carbon fiber production recovery liquid with potassium thiocyanate to obtain a mixed solution to be tested; recording an infrared absorption spectrum of the mixed solution to be measured; calculating the peak height ratio of each component of the polyacrylonitrile-based carbon fiber production recovery liquid to potassium thiocyanate, substituting the peak height ratio into a standard working curve, and calculating the mass ratio of each component of the polyacrylonitrile-based carbon fiber production recovery liquid in the polyacrylonitrile-based carbon fiber production recovery liquid. The detection method can rapidly, accurately and simply detect the component content in the polyacrylonitrile-based carbon fiber production recovery liquid.
Description
Technical Field
The application relates to the technical field of detection and analysis, in particular to a method for detecting the component content of a recovery liquid in polyacrylonitrile-based carbon fiber production.
Background
Carbon fiber has high performance advantage and is widely applied in various fields, and along with the deep development of the carbon fiber industry and the change of market demands, higher requirements are put forward for carbon fiber production enterprises, and the popularization and application of the carbon fiber are still limited by high production cost, so that how to reduce the production cost of the carbon fiber field becomes the key field of current research.
The polyacrylonitrile-based carbon fiber is mainly produced by polymerizing solvents such as acrylonitrile, dimethyl sulfoxide and the like under a series of reaction conditions. In order to reduce the production cost, the reacted solution can be recycled. The main components of the polyacrylonitrile-based carbon fiber production recovery liquid are dimethyl sulfoxide and a small amount of acrylonitrile, and in order to ensure the product quality of the carbon fiber, the content of main substances in the polyacrylonitrile-based carbon fiber production recovery liquid needs to be accurately measured.
At present, the acrylonitrile content is mainly detected by adopting a titration method, the dimethyl sulfoxide content is detected by adopting an Abbe refractometer, the micro-ingredient content is detected by adopting a gas chromatograph, and the like, but the manual titration can cause larger errors, and the gas chromatograph is complex in operation and can not detect in batches, so that the timeliness is poor; in addition, if it is necessary to detect the contents of various components in the polyacrylonitrile-based carbon fiber production recovery liquid, at least two or more methods are required, further resulting in a decrease in the working efficiency.
Therefore, it is necessary to find a method for detecting the component content of the recovery liquid in the production of the polyacrylonitrile-based carbon fiber.
Disclosure of Invention
In order to solve the technical problems, the application provides a method for detecting the component content of the recovery liquid in the production of the polyacrylonitrile carbon fiber, which can realize the rapid and accurate detection of the component content in the recovery liquid in the production of the polyacrylonitrile carbon fiber.
The application provides a detection method for the component content of a recovery liquid in polyacrylonitrile carbon fiber production, which comprises the following steps:
s1, preparing a standard solution, namely mixing potassium thiocyanate with the standard solution according to a preset mass ratio by taking the potassium thiocyanate as an internal standard substance to obtain a series of mixed standard solutions;
s2, respectively carrying out infrared spectrum curve scanning on the series of mixed standard solutions, and recording an infrared absorption spectrum chart;
s3, respectively measuring the peak heights of each characteristic absorption peak in the series of mixed standard solutions according to the infrared absorption spectrogram in S2, respectively calculating the peak height ratio and the mass ratio of each component of the series of mixed standard solutions to the potassium thiocyanate, and drawing a standard working curve;
s4, mixing the polyacrylonitrile-based carbon fiber production recovery liquid with the potassium thiocyanate to obtain a mixed solution to be tested; carrying out infrared spectrum curve scanning on the mixed solution to be detected, and recording an infrared absorption spectrum chart; and respectively measuring peak heights of characteristic absorption peaks in the mixed solution to be measured, respectively calculating peak height ratios of components of the polyacrylonitrile-based carbon fiber production recovery liquid and potassium thiocyanate, substituting a standard working curve, and calculating mass ratios of the components of the polyacrylonitrile-based carbon fiber production recovery liquid in the polyacrylonitrile-based carbon fiber production recovery liquid.
In some embodiments of the application, in the step S1, the standard solution is prepared from 75-90wt% dimethyl sulfoxide, 9.5-24.5wt% acrylonitrile and 0.5-1.5wt% water.
In some embodiments of the application, in the step S1, the standard solution is prepared from 75-85wt% dimethyl sulfoxide, 14-23.5wt% acrylonitrile and 1-1.5wt% water.
In some embodiments of the application, in the step S1, the standard solution is prepared from 85wt% dimethyl sulfoxide, 14wt% acrylonitrile, and 1wt% water.
In some embodiments of the present application, in the step S1, the predetermined mass ratio is 1:30 to 1:3.
In some embodiments of the present application, in the step S3, peak height ratios of the components of the series of mixed standard solutions to the potassium thiocyanate are calculated, respectively, that is, peak height ratios of the acrylonitrile at 2230cm are calculated, respectively -1 Characteristic absorption peak height and 2067cm of potassium thiocyanate -1 A ratio of characteristic absorption peak heights, andthe dimethyl sulfoxide is 1010cm -1 Characteristic absorption peak height and 2067cm of potassium thiocyanate -1 Ratio of characteristic absorption peak heights.
In some embodiments of the present application, the characteristic absorption peak height of acrylonitrile, the characteristic absorption peak height of potassium thiocyanate, and the characteristic absorption peak height of dimethyl sulfoxide are measured by a baseline method.
In some embodiments of the present application, in the step S4, a mass ratio of the polyacrylonitrile-based carbon fiber production recovery solution to the potassium thiocyanate is 32:1-2:1.
In some embodiments of the present application, in the step S3, a regression equation of the standard working curve of acrylonitrile and potassium thiocyanate is: y=0.00811+0.09778x, r 2 ＝0.99221；
Wherein x is the mass ratio of acrylonitrile to potassium thiocyanate, and y is the peak height ratio of acrylonitrile to potassium thiocyanate.
In some embodiments of the present application, in the step S3, a regression equation of the standard working curves of dimethyl sulfoxide and potassium thiocyanate is: y=0.01484+0.44513x, r 2 ＝0.99634；
Wherein x is the mass ratio of dimethyl sulfoxide to potassium thiocyanate, and y is the peak height ratio of dimethyl sulfoxide to potassium thiocyanate.
The technical scheme provided by the embodiment of the application can comprise the following beneficial effects: according to the application, potassium thiocyanate is used as an internal standard, a model is built according to the lambert-beer law, so that the component content in the polyacrylonitrile carbon fiber production recovery liquid can be rapidly, accurately and simply detected, the recovery liquid is recycled for actual production, the production cost is reduced, and data support and correct guidance are provided.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application as claimed.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
FIG. 1 is a flow chart illustrating a method for detecting the component content of a polyacrylonitrile-based carbon fiber production recovery liquid according to an exemplary embodiment.
FIG. 2 is a standard operating curve of the absorbance ratio to mass ratio of acrylonitrile and potassium thiocyanate shown in example 1.
FIG. 3 is a standard working curve of absorbance ratio-to-mass ratio of dimethyl sulfoxide and potassium thiocyanate shown in example 1.
Fig. 4 is a graph of comparative example 1 showing the characteristic absorption peak heights tested using the baseline method.
Fig. 5 is a graph showing the characteristic absorption peak heights measured using the tangent method shown in comparative example 2.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to the embodiments of the present application and the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application. It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be arbitrarily combined with each other.
Carbon fiber has high performance advantage and is widely applied in various fields, and along with the deep development of the carbon fiber industry and the change of market demands, higher requirements are put forward for carbon fiber production enterprises, and the popularization and application of the carbon fiber are still limited by high production cost, so that how to reduce the production cost of the carbon fiber field becomes the key field of current research.
The polyacrylonitrile-based carbon fiber is mainly produced by polymerizing solvents such as acrylonitrile, dimethyl sulfoxide and the like under a series of reaction conditions. In order to reduce the production cost, the reacted solution can be recycled. The main components of the polyacrylonitrile-based carbon fiber production recovery liquid are dimethyl sulfoxide and a small amount of acrylonitrile, and in order to ensure the product quality of the carbon fiber, the content of main substances in the polyacrylonitrile-based carbon fiber production recovery liquid needs to be accurately measured.
At present, the acrylonitrile content is mainly detected by adopting a titration method, the dimethyl sulfoxide content is detected by adopting an Abbe refractometer, the micro-ingredient content is detected by adopting a gas chromatograph, and the like, but the manual titration can cause larger errors, and the gas chromatograph is complex in operation and can not detect in batches, so that the timeliness is poor; in addition, if it is necessary to detect the contents of various components in the polyacrylonitrile-based carbon fiber production recovery liquid, at least two or more methods are required, further resulting in a decrease in the working efficiency.
Based on the method, the application provides a detection method for the component content of the recovery liquid in the production of the polyacrylonitrile-based carbon fiber, which takes potassium thiocyanate as an internal standard substance, and carries out infrared spectrum scanning on a series of mixed standard solutions mixed by potassium thiocyanate and standard solutions in a predetermined mass ratio to obtain an infrared absorption spectrum; according to the infrared absorption spectrum, measuring the peak height of each characteristic absorption peak in a series of mixed standard solutions, calculating the peak height ratio and the mass ratio of each component of the standard solution to potassium thiocyanate, and drawing a standard working curve; mixing the polyacrylonitrile-based carbon fiber production recovery liquid with potassium thiocyanate to obtain a mixed solution to be detected, carrying out infrared spectrum curve scanning on the mixed solution to be detected, recording an infrared absorption spectrum chart, respectively measuring peak heights of each characteristic absorption peak in the mixed solution to be detected, respectively calculating peak height ratios of each component of the polyacrylonitrile-based carbon fiber production recovery liquid and the potassium thiocyanate, substituting the peak height ratios into a standard working curve, and calculating mass ratios of each component of the polyacrylonitrile-based carbon fiber production recovery liquid in the polyacrylonitrile-based carbon fiber production recovery liquid. The method can be used for simultaneously detecting various components in the polypropylene-based carbon fiber production recovery liquid, such as acrylonitrile and dimethyl sulfoxide, and has the advantages of simple and quick detection method, accurate detection result and small error.
In an exemplary embodiment of the present application, referring to fig. 1, the embodiment provides a method for detecting the component content of a recovery liquid in the production of polyacrylonitrile-based carbon fiber, which includes the following steps:
s1, preparing a standard solution, taking potassium thiocyanate as an internal standard substance, and mixing the potassium thiocyanate with the standard solution according to a preset mass ratio to obtain a series of mixed standard solutions;
s2, respectively carrying out infrared spectrum curve scanning on the series of mixed standard solutions, and recording an infrared absorption spectrum chart;
s3, respectively measuring the peak heights of each characteristic absorption peak in the series of mixed standard solutions according to the infrared absorption spectrogram in S2, respectively calculating the peak height ratio and the mass ratio of each component of the series of mixed standard solutions to potassium thiocyanate, and drawing a standard working curve;
s4, mixing the polyacrylonitrile-based carbon fiber production recovery liquid with potassium thiocyanate to obtain a mixed solution to be tested; carrying out infrared spectrum curve scanning on the mixed solution to be detected, and recording an infrared absorption spectrum chart; and respectively measuring peak heights of characteristic absorption peaks in the mixed solution to be measured, respectively calculating peak height ratios of components of the polyacrylonitrile-based carbon fiber production recovery liquid and potassium thiocyanate, substituting the peak height ratios into a standard working curve, and calculating mass ratios of the components of the polyacrylonitrile-based carbon fiber production recovery liquid in the polyacrylonitrile-based carbon fiber production recovery liquid.
In the embodiment, a solution system is used for establishing a detection method for the component content of the polyacrylonitrile-based carbon fiber production recovery liquid, solid potassium thiocyanate is used as an internal standard, and a standard working curve model is established according to the lambert-beer law, so that the component content of the polyacrylonitrile-based carbon fiber production recovery liquid, such as acrylonitrile and dimethyl sulfoxide, can be rapidly, accurately and simply detected, and the production recovery liquid can be reused conveniently.
In one embodiment, in step S1, the standard solution is formulated from 75-90wt% dimethyl sulfoxide, 9.5-24.5wt% acrylonitrile, and 0.5-1.5wt% water.
In the production process of the polyacrylonitrile-based carbon fiber precursor, an acrylonitrile monomer is polymerized by taking dimethyl sulfoxide as a solvent, and the obtained polymer is used for producing the carbon fiber precursor after being separated. Wherein dimethyl sulfoxide is used as a solvent in the polymerization reaction, is a main component in the production and recovery liquid of the polyacrylonitrile carbon fiber, and also comprises a part of unreacted acrylonitrile and a small amount of water in the production and recovery liquid. The embodiment mainly detects the contents of dimethyl sulfoxide and acrylonitrile in the polyacrylonitrile-based carbon fiber production recovery liquid, so that the standard solution is prepared from dimethyl sulfoxide, acrylonitrile and water in a certain proportion. The content of each component in the produced recovery liquid is different in different production processes; when the standard solution is prepared from 75-90wt% of dimethyl sulfoxide, 9.5-24.5wt% of acrylonitrile and 0.5-1.5wt% of water, the detection of the dimethyl sulfoxide and acrylonitrile content in the recovered liquid of the polyacrylonitrile-based carbon fiber production under most production processes at present can be satisfied.
Illustratively, the standard solution is suitable for detecting production recovery liquid with the dimethyl sulfoxide content of 60-92wt%, the acrylonitrile content of 8-40wt% and the water content of 0.1-1wt% when the standard solution is prepared from 75-90wt% of dimethyl sulfoxide, 9.5-24.5wt% of acrylonitrile and 0.5-1.5wt% of water.
Preferably, in step S1, the standard solution is formulated from 75-85wt% dimethyl sulfoxide, 14-23.5wt% acrylonitrile, and 1-1.5wt% water. Further, the standard solution was formulated from 85wt% dimethyl sulfoxide, 14wt% acrylonitrile, and 1wt% water.
Wherein, when the standard solution is prepared from 85wt% of dimethyl sulfoxide, 14wt% of acrylonitrile and 1wt% of water, the method is applicable to the detection of production recovery liquid with the dimethyl sulfoxide content of 60-92wt%, the acrylonitrile content of 8-40wt% and the water content of 0.1-1 wt%. For example, the production recovery fluid comprises 85.02wt% dimethyl sulfoxide, 13.99wt% and 0.99wt% water; alternatively, the production recovery fluid comprises 90.74wt% dimethyl sulfoxide, 8.95wt% acrylonitrile, and 0.21wt% water; alternatively still, the production recovery fluid comprises 60.02wt% dimethyl sulfoxide, 39.01wt% acrylonitrile, and 0.97wt% water.
In one embodiment, the predetermined mass ratio is 1:30 to 1:3.
In this example, potassium thiocyanate and standard solution were taken and mixed in mass ratios of 1:30, 1:29, 1:28 … …, 1:4, 1:3 (accurate to.+ -. 0.0001 g) to obtain 28 sets of series mixed standard solutions.
In one embodiment, in step S3, peak height ratios of the components of the series of mixed standard solutions and potassium thiocyanate are calculated respectively, namely acrylonitrile at 2230cm -1 Characteristic absorption peak height and potassium thiocyanate of 2067cm -1 Characteristic absorption peak height ratio and dimethyl sulfoxide ratio of 1010cm -1 Characteristic absorption peak height and potassium thiocyanate of 2067cm -1 Ratio of characteristic absorption peak heights.
In one embodiment, the characteristic absorption peak height of acrylonitrile, the characteristic absorption peak height of potassium thiocyanate, and the characteristic absorption peak height of dimethyl sulfoxide are measured using a baseline method. Compared with the tangent method, the embodiment adopts the baseline method to measure the absorption peak heights of each characteristic on the infrared absorption spectrum, has smaller error, and is beneficial to improving the accuracy of the detection result.
In one embodiment, in step S3, the regression equation of the standard working curve of acrylonitrile and potassium thiocyanate is: y=0.00811+0.09778x, r 2 ＝0.99221；
Wherein x is the mass ratio of acrylonitrile to potassium thiocyanate, and y is the peak height ratio of acrylonitrile to potassium thiocyanate.
In the step S3, the regression equation of the standard working curves of dimethyl sulfoxide and potassium thiocyanate is: y=0.01484+0.44513x, r 2 ＝0.99634；
Wherein x is the mass ratio of dimethyl sulfoxide to potassium thiocyanate, and y is the peak height ratio of dimethyl sulfoxide to potassium thiocyanate.
The regression equation of the absorbance ratio-mass ratio standard working curve of acrylonitrile and potassium thiocyanate of this example has correlation coefficient R 2 And the correlation coefficient R of the regression equation of the standard working curve of the absorbance ratio-mass ratio of dimethyl sulfoxide and potassium thiocyanate 2 All are larger than 0.99, which shows that the linear correlation of the standard working curve established by the method of the embodiment is better, and the detection precision of the content of each component in the production recovery liquid is higher.
In order to more clearly explain the technical scheme of the application, the application enumerates specific embodiments of the detection method for the component content of the polyacrylonitrile-based carbon fiber production recovery liquid, and the beneficial effects are illustrated by specific experimental data given by the specific embodiments.
It should be noted that, the "content" herein refers to "mass percent content"; the peak height of the characteristic absorption peak, namely the absorbance, and the ratio of the characteristic absorption peak height of each component of the series of mixed standard solutions to the characteristic absorption peak height of potassium thiocyanate, namely the absorbance ratio.
Examples
Example 1: a detection method for the component content of a polyacrylonitrile-based carbon fiber production recovery liquid comprises the following steps:
(1) Preparing a standard solution: 85g of dimethyl sulfoxide, 14g of acrylonitrile and 1g of water are taken and uniformly mixed to prepare a standard solution.
(2) Taking solid potassium thiocyanate as an internal standard, taking potassium thiocyanate and a standard solution, and mixing the potassium thiocyanate and the standard solution according to the mass ratio of 1:30, 1:29, 1:28 … …, 1:4 and 1:3, wherein the mass ratio is accurately weighed (the mass ratio is accurate to +/-0.0001 g), so as to obtain 28 groups of series mixed standard solutions.
(3) The 28 sets of mixed standard solutions were each subjected to infrared spectrum scanning, and their respective infrared absorption spectra were recorded.
(4) Measuring acrylonitrile in 28 groups of mixed standard solutions at 2230cm by a baseline method according to the infrared absorption spectrum in the step (3) -1 Characteristic absorption peak height, potassium thiocyanate of 2067cm -1 Characteristic absorption peak height and dimethyl sulfoxide of 1010cm -1 The characteristic absorption peak heights are calculated respectively, and the ratio and the mass ratio of the characteristic absorption peak heights of acrylonitrile to the characteristic absorption peak heights of potassium thiocyanate in 28 groups of mixed standard solutions and the ratio and the mass ratio of the characteristic absorption peak heights of dimethyl sulfoxide to the characteristic absorption peak heights of potassium thiocyanate in 28 groups of mixed standard solutions are calculated respectively; according to the obtained data, respectively drawing a standard working curve of the absorbance ratio-mass ratio of the acrylonitrile (shown in figure 2) and a standard working curve of the absorbance ratio-mass ratio of the dimethyl sulfoxide (shown in figure 3);
the curve regression equation for the standard working curve of the absorbance ratio-mass ratio of acrylonitrile is:
y＝0.00811+0.09778x，R 2 ＝0.99221；
wherein x is the mass ratio of acrylonitrile to potassium thiocyanate, and y is the absorbance ratio of acrylonitrile to potassium thiocyanate;
the curve regression equation of the standard working curve of the absorbance ratio-mass ratio of dimethyl sulfoxide is:
y＝0.01484+0.44513x，R 2 ＝0.99634；
wherein x is the mass ratio of dimethyl sulfoxide to potassium thiocyanate, and y is the absorbance ratio of dimethyl sulfoxide to potassium thiocyanate.
(5) Respectively weighing a polyacrylonitrile-based carbon fiber production recovery solution m1 and potassium thiocyanate m2, and fully and uniformly mixing the two solutions to obtain a mixed solution to be detected; carrying out infrared spectrum curve scanning on the mixed solution to be detected, and recording an infrared absorption spectrum chart; measuring the potassium thiocyanate in the mixed solution to be measured at 2067cm by adopting a baseline method -1 Characteristic absorption peak height A1 and acrylonitrile of 2230cm -1 Characteristic absorption peak height A2 and dimethyl sulfoxide of 1010cm -1 And (3) respectively calculating the ratio of the characteristic absorption peak height of acrylonitrile to the characteristic absorption peak height of potassium thiocyanate and the ratio of the characteristic absorption peak height of dimethyl sulfoxide to the characteristic absorption peak height of potassium thiocyanate, and substituting the data into a regression equation of a standard working curve of the absorbance ratio-mass ratio of acrylonitrile and the absorbance ratio-mass ratio of dimethyl sulfoxide in the step (4) to calculate the mass ratio of acrylonitrile to potassium thiocyanate and the mass ratio of dimethyl sulfoxide to potassium thiocyanate, thereby calculating the content of acrylonitrile and dimethyl sulfoxide in the polyacrylonitrile-based carbon fiber production recovery liquid.
When the characteristic absorption peak heights are measured, the mass ratio of acrylonitrile (AN%) and dimethyl sulfoxide (DMSO%) in the polyacrylonitrile-based carbon fiber production recovery liquid can be calculated according to the following formulas (I) and (II) respectively;
verification test
To verify the accuracy of the acrylonitrile and dimethyl sulfoxide content detection in the polyacrylonitrile-based carbon fiber production recovery liquid by the method of example 1, the following verification test was performed:
verification test one:
(1) preparing a solution to be tested: 85.02g of dimethyl sulfoxide, 13.99g of acrylonitrile and 0.99g of water are taken and uniformly mixed to prepare a solution A to be detected.
(2) Preparing a mixed solution to be tested:
14.9875g of a solution A to be detected and 1.0012g of potassium thiocyanate are weighed and fully and uniformly mixed to obtain a mixed solution a to be detected;
10.0129g of a solution A to be detected and 1.0041g of potassium thiocyanate are weighed and fully and uniformly mixed to obtain a mixed solution b to be detected;
5.0014g of a solution A to be detected and 9.8646g of potassium thiocyanate are weighed and fully and uniformly mixed to obtain a mixed solution c to be detected;
3.1421g of a solution A to be tested and 1.0145g of potassium thiocyanate are weighed and fully and uniformly mixed to obtain a mixed solution d to be tested.
(3) Determination of infrared absorption spectrum: and respectively carrying out infrared spectrum curve scanning on the mixed solution to be detected a, the mixed solution to be detected b, the mixed solution to be detected c and the mixed solution to be detected d, and recording the infrared absorption spectrograms of the mixed solution to be detected a, the mixed solution to be detected b, the mixed solution to be detected c and the mixed solution to be detected d.
(4) Measuring characteristic absorption peak height: measuring the potassium thiocyanate in the mixed solution a, the mixed solution b to be measured, the mixed solution c to be measured and the mixed solution d to be measured respectively at 2067cm by adopting a baseline method -1 Characteristic absorption peak height, acrylonitrile at 2230cm -1 Characteristic absorption peak height and dimethyl sulfoxide of 1010cm -1 The characteristic absorption peak heights are respectively substituted into the formula (I) and the formula (II) in the example 1, and the acrylonitrile and the dimethyl sulfoxide in the solution to be detected are respectively calculatedThe content, and calculate the error between the content of each component in the solution to be measured obtained by the method of example 1 and the content of each component in the solution to be measured actually prepared:
error= (content of each component in the test solution was measured by the method of example 1-content of each component in the test solution actually prepared) ×100%.
The test results are shown in Table 1.
TABLE 1 detection Table of the contents of Acrylonitrile and dimethyl sulfoxide in Mixed solutions a-d to be measured
As can be seen from the data in Table 1, when the to-be-detected mixed solutions a-d are prepared from the to-be-detected solutions with different mass ratios and potassium thiocyanate, the error between the content of acrylonitrile and dimethyl sulfoxide in the to-be-detected solution obtained by the method in example 1 and the content of the above components in the to-be-detected solution, which are actually prepared, is less than 0.05%, which indicates that the error is smaller and the accuracy is higher when the method in example 1 of the application is used for detecting acrylonitrile and dimethyl sulfoxide in the recovery liquid of polyacrylonitrile-based carbon fiber production.
And II, verification test:
(1) taking an on-line recovery liquid, and testing the content of the on-line recovery liquid by adopting a gas chromatography method to obtain the content of each component in the on-line recovery liquid as follows: dimethyl sulfoxide 90.74%, acrylonitrile 8.95%, and water 0.21%.
(2) Preparing a mixed solution to be tested: 5.2010g of a solution to be detected and 1.0105g of potassium thiocyanate are weighed and fully and uniformly mixed to obtain a mixed solution e to be detected;
(3) determination of infrared absorption spectrum: and carrying out infrared spectrum curve scanning on the mixed solution e to be detected, and recording an infrared absorption spectrum chart of the mixed solution e.
(4) Measuring characteristic absorption peak height: measurement of Potassium thiocyanate in Mixed solution e at 2067cm Using baseline method -1 Characteristic absorption peak height, acrylonitrile at 2230cm -1 Characteristic absorption peak height and dimethyl sulfoxide of 1010cm -1 Characteristic absorption peak heights ofThe contents of acrylonitrile in the on-line recovered liquid were calculated to be 8.97%, the detection error was 0.02%, the content of dimethyl sulfoxide in the solution to be measured was 90.69%, and the detection error was-0.05% respectively in the formulae (I) and (II) in example 1.
From the results, the error between the content of acrylonitrile and dimethyl sulfoxide in the on-line recovery liquid obtained by the method of the embodiment 1 and the content of each component detected by the gas chromatography in the solution to be detected is less than or equal to 0.05%, which indicates that the error is smaller and the accuracy is higher when the method of the embodiment 1 is used for detecting the acrylonitrile and the dimethyl sulfoxide in the recovery liquid in the production of the polyacrylonitrile-based carbon fiber.
Verification test three:
(1) preparing a solution to be tested: 60.02g of dimethyl sulfoxide, 39.01g of acrylonitrile and 0.97g of water are taken and uniformly mixed to prepare a solution B to be detected.
(2) Preparing a mixed solution to be tested:
3.7149g of a solution B to be tested and 1.0012g of potassium thiocyanate are weighed and fully and uniformly mixed to obtain a mixed solution f to be tested.
(3) Determination of infrared absorption spectrum: and (3) carrying out infrared spectrum curve scanning on the mixed solution f to be detected, and recording an infrared absorption spectrum chart of the mixed solution f.
(4) Measuring characteristic absorption peak height: measurement of Potassium thiocyanate in Mixed solution f at 2067cm Using baseline method -1 Characteristic absorption peak height, acrylonitrile at 2230cm -1 Characteristic absorption peak height and dimethyl sulfoxide of 1010cm -1 The characteristic absorption peak heights are respectively substituted into the formula (I) and the formula (II) in the example 1, the content of acrylonitrile in the solution to be detected is respectively calculated to be 40.21%, the detection error is 1.2%, the content of dimethyl sulfoxide in the solution to be detected is 58.98% by weight, and the detection error is-1.04%.
From this, the error between the content of acrylonitrile and dimethyl sulfoxide in the solution to be measured obtained by the method of example 1 and the content of each component actually prepared in the solution to be measured is less than or equal to 1.2%, which indicates that the error is smaller and the accuracy is higher when the method of example 1 is used for detecting acrylonitrile and dimethyl sulfoxide in the recovered liquid in the production of polyacrylonitrile-based carbon fiber.
It can be seen from the combination of the first verification test and the third verification test that the error in detecting the content of each component in the production recovery liquid is smaller by the method of example 1 when the content of each component in the standard solution is closer to the content of each component in the actual production recovery liquid. In actual production, corresponding standard solutions can be prepared according to different production processes of carbon fibers; the standard solution with the same component concentration can be selected after the content of each component in the production recovery liquid under different production processes is detected, and the standard solution is adapted to the production recovery liquid under different production processes within an allowable error range.
Example 2:
this example differs from example 1 in that the standard solution is formulated from 75wt% dimethyl sulfoxide, 23.5wt% acrylonitrile, and 1.5wt% water.
This example was obtained by modeling according to the test procedure in example 1:
the regression equation for the standard working curve of acrylonitrile and potassium thiocyanate is: y=0.00810+0.097811 x, r 2 ＝0.99243；
Wherein x is the mass ratio of acrylonitrile to potassium thiocyanate, and y is the peak height ratio of acrylonitrile to potassium thiocyanate.
The regression equation for the standard working curves of dimethyl sulfoxide and potassium thiocyanate is: y=0.01479+0.44757 x, r 2 ＝0.99694；
Correlation coefficient R according to example 1 and example 2 2 It can be seen that the accuracy of the detection of acrylonitrile and dimethyl sulfoxide in the production of the recovered liquid was substantially uniform by the methods of examples 1 and 2. Therefore, the standard solution prepared from 75-90wt% of dimethyl sulfoxide, 9.5-24.5wt% of acrylonitrile and 0.5-1.5wt% of water can be used for establishing a correct test model, and has higher detection accuracy when the detection of acrylonitrile and dimethyl sulfoxide of production recovery liquid is carried out.
Comparative example
Comparative example 1: this comparative example and example 1The difference is that: the potassium thiocyanate solution (0.1 mol/L) is used as an internal standard, and a baseline method (shown in figure 4) is adopted to respectively measure acrylonitrile in a series of mixed standard solutions at 2230cm -1 Characteristic absorption peak height, potassium thiocyanate of 2067cm -1 Characteristic absorption peak height and dimethyl sulfoxide of 1010cm -1 The characteristic absorption peak height, the ratio of the characteristic absorption peak height of acrylonitrile to the characteristic absorption peak height of potassium thiocyanate and the mass ratio are calculated respectively, a standard working curve is drawn, the ratio of the characteristic absorption peak height of dimethyl sulfoxide to the characteristic absorption peak height of potassium thiocyanate and the mass ratio are calculated, and the standard working curve is drawn:
the curve regression equation for the standard working curve of the absorbance ratio-mass ratio of acrylonitrile is:
y＝0.00404+0.07607x，R 2 ＝0.91247；
wherein x is the mass ratio of acrylonitrile to potassium thiocyanate, and y is the absorbance ratio of acrylonitrile to potassium thiocyanate;
the curve regression equation of the standard working curve of the absorbance ratio-mass ratio of dimethyl sulfoxide is:
y＝-0.83421+1.36099x，R 2 ＝0.93874；
wherein x is the mass ratio of dimethyl sulfoxide to potassium thiocyanate, and y is the absorbance ratio of dimethyl sulfoxide to potassium thiocyanate.
As can be seen from example 1 and comparative example 1, the correlation coefficient R of the standard operating curve of comparative example 1 2 Significantly smaller than the correlation coefficient R of example 1 2 It was revealed that the method of example 1 was used to detect acrylonitrile and dimethyl sulfoxide in the production recovery liquid with higher accuracy. It is clear from this that in the present application, the accuracy of the standard working curve obtained is higher when solid potassium thiocyanate is used as an internal standard than when potassium thiocyanate solution is used.
Comparative example 2: this comparative example differs from example 1 in that acrylonitrile in a series of mixed standard solutions was measured at 2230cm by the tangential method (as shown in FIG. 5) -1 Characteristic absorption peak height, potassium thiocyanate of 2067cm -1 Characteristic absorption peak height and dimethyl sulfoxide of 1010cm -1 The characteristic absorption peak height, the ratio of the characteristic absorption peak height of acrylonitrile to the characteristic absorption peak height of potassium thiocyanate and the mass ratio are calculated respectively, a standard working curve is drawn, the ratio of the characteristic absorption peak height of dimethyl sulfoxide to the characteristic absorption peak height of potassium thiocyanate and the mass ratio are calculated, and the standard working curve is drawn:
the curve regression equation for the standard working curve of the absorbance ratio-mass ratio of acrylonitrile is:
y＝0.05338+0.08043x，R 2 ＝0.83706；
wherein x is the mass ratio of acrylonitrile to potassium thiocyanate, and y is the absorbance ratio of acrylonitrile to potassium thiocyanate;
the curve regression equation of the standard working curve of the absorbance ratio-mass ratio of dimethyl sulfoxide is:
y＝0.1164+0.43034x，R 2 ＝0.92614；
wherein x is the mass ratio of dimethyl sulfoxide to potassium thiocyanate, and y is the absorbance ratio of dimethyl sulfoxide to potassium thiocyanate
As can be seen from example 1 and comparative example 2, the method of example 1 was used to detect acrylonitrile and dimethyl sulfoxide in the production of the recovered liquid with higher accuracy. In the application, the accuracy of the characteristic absorption peak height measured by the baseline method is higher, and the accuracy of the obtained standard working curve is higher.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting. Although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims (10)
1. The method for detecting the component content of the polyacrylonitrile-based carbon fiber production recovery liquid is characterized by comprising the following steps of:
s1, preparing a standard solution, namely mixing potassium thiocyanate with the standard solution according to a preset mass ratio by taking the potassium thiocyanate as an internal standard substance to obtain a series of mixed standard solutions;
s2, respectively carrying out infrared spectrum curve scanning on the series of mixed standard solutions, and recording an infrared absorption spectrum chart;
s3, respectively measuring the peak heights of each characteristic absorption peak in the series of mixed standard solutions according to the infrared absorption spectrogram in S2, respectively calculating the peak height ratio and the mass ratio of each component of the series of mixed standard solutions to the potassium thiocyanate, and drawing a standard working curve;
s4, mixing the polyacrylonitrile-based carbon fiber production recovery liquid with the potassium thiocyanate to obtain a mixed solution to be tested; carrying out infrared spectrum curve scanning on the mixed solution to be detected, and recording an infrared absorption spectrum chart; and respectively measuring peak heights of characteristic absorption peaks in the mixed solution to be measured, respectively calculating peak height ratios of components of the polyacrylonitrile-based carbon fiber production recovery liquid and potassium thiocyanate, substituting a standard working curve, and calculating mass ratios of the components of the polyacrylonitrile-based carbon fiber production recovery liquid in the polyacrylonitrile-based carbon fiber production recovery liquid.
2. The method according to claim 1, wherein in the step S1, the standard solution is prepared from 75-90wt% of dimethyl sulfoxide, 9.5-24.5wt% of acrylonitrile, and 0.5-1.5wt% of water.
3. The method according to claim 2, wherein in the step S1, the standard solution is prepared from 75-85wt% of dimethyl sulfoxide, 14-23.5wt% of acrylonitrile, and 1-1.5wt% of water.
4. The method according to claim 3, wherein in the step S1, the standard solution is prepared from 85wt% dimethyl sulfoxide, 14wt% acrylonitrile and 1wt% water.
5. The method according to claim 1, wherein in the step S1, the predetermined mass ratio is 1:30 to 1:3.
6. The method according to claim 2, wherein in the step S3, peak height ratios of the components of the series of mixed standard solutions to the potassium thiocyanate are calculated, respectively, by calculating the acrylonitrile at 2230cm -1 Characteristic absorption peak height and 2067cm of potassium thiocyanate -1 Characteristic absorption peak height ratio and the dimethyl sulfoxide is 1010cm -1 Characteristic absorption peak height and 2067cm of potassium thiocyanate -1 Ratio of characteristic absorption peak heights.
7. The method according to claim 6, wherein the characteristic absorption peak height of acrylonitrile, the characteristic absorption peak height of potassium thiocyanate, and the characteristic absorption peak height of dimethyl sulfoxide are measured by a baseline method.
8. The detection method according to claim 1, wherein in the step S4, a mass ratio of the polyacrylonitrile-based carbon fiber production recovery solution to the potassium thiocyanate is 32:1-2:1.
9. The detection method according to claim 1, wherein in the step S3, a regression equation of the standard operation curve of acrylonitrile and potassium thiocyanate is: y=0.00811+0.09778x, r 2 ＝0.99221；
Wherein x is the mass ratio of acrylonitrile to potassium thiocyanate, and y is the peak height ratio of acrylonitrile to potassium thiocyanate.
10. The detection method according to claim 1, wherein in the step S3, a regression equation of the standard working curves of dimethyl sulfoxide and potassium thiocyanate is: y=0.01484+0.44513x, r 2 ＝0.99634；
Wherein x is the mass ratio of dimethyl sulfoxide to potassium thiocyanate, and y is the peak height ratio of dimethyl sulfoxide to potassium thiocyanate.
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