Method for preparing catalyst and method for detecting metal oxide-encrypted chemical fiber

Abstract

The present application relates to the technical field of fabric testing, in particular to a catalyst preparation method and a detection method of metal oxide encrypted chemical fibers, the detection method comprising: mixing the chemical fibers to be detected with a catalyst, then performing high-temperature decomposition treatment; then screening and removing the catalyst to obtain solid powder; using a fluorescent agent to rapidly characterize whether the solid powder contains metal ions; and determining the ion type and content through fluorescence emission spectrum. The detection method can quickly and accurately identify the type and content of metal oxides in the chemical fibers, and the detection method can first determine whether the chemical fibers contain metal elements and whether they can be tracked through the fluorescent labeling. The tracking method is also fast, accurate and simple to operate, and can identify the chemical fibers containing metal oxide anti-counterfeiting tracking.

Description

TECHNICAL FIELD

[0001] The present application relates to a catalyst preparation method and a detection method of metal oxide encrypted chemical fibers, and belongs to the technical field of fabric testing. BACKGROUND

[0002] Anti-fake chemical fibers are functional fibers endowed with identifiable and difficult-to-copy anti-fake properties through special material design and processing technology. The core of anti-fake chemical fibers is to introduce special marker substances or structural features into the fibers to make them have concealment, uniqueness and traceability, and to realize authenticity verification by detecting the characteristics of the marker substances (such as metal element ratio, spectral response).

[0003] Patent applications with publication numbers CN112063123A, CN112064129A and CN112064140A all disclose the use of metal oxides to prepare anti-fake chemical fibers, so that the chemical fibers can have memory tracking properties, identification functions and anti-fake concealment.

[0004] Currently, the detection method of chemical fibers encrypted with metal oxides needs to be analyzed by electron microscopy, but the metal oxides exist inside the fibers, which is not convenient to observe directly by electron microscopy. It is necessary to dissolve with an acid solution and then test the spectrum after constant volume. For example, patent application with publication number CN112067599A discloses a detection method of anti-fake chemical fibers, which comprises: 1) sampling, adding the obtained sample of anti-fake chemical fibers into a mixed acid solution to obtain a premix; 2) performing digestion treatment on the premix, performing acid removal treatment on the digested solution, constant volume to obtain a constant volume solution; 3) performing element quantitative analysis on the constant volume solution. However, the type of acid solution is not easy to choose, the cost of spectral testing is high, the efficiency is low, and only when the type of metal oxide is known in advance can the appropriate type of acid solution be used. At the same time, the chemical fibers are also dissolved in some acid solutions, which affects the detection results.

[0005] Therefore, it is of great value to develop a method that can quickly and accurately identify the type and content of metal oxides in chemical fibers for decryption detection of chemical fibers. It can be used as an identification method for recycling chemical fibers or as a fast and accurate positioning method for fiber batches and manufacturers to view the flow process and results of different fibers in each batch and prevent others from counterfeiting. At the same time, it also takes into account the fast, safe, accurate and low-cost testing method. SUMMARY

[0006] The present application aims at the deficiencies in the prior art, and provides a catalyst preparation method and a detection method for metal oxide encrypted chemical fibers, which can quickly and accurately identify the type and content of metal oxides in chemical fibers, and the catalyst used in fiber decomposition can make the solid powder not contain other substances affecting the detection process, and the added tracer can be clearly screened out, the fiber is efficiently decomposed and no black carbonization residue is left, and the product after fiber decomposition is metal oxide; the catalyst can be regenerated after participating in the reaction; the laboratory controllability and safety controllability are high.

[0007] The technical scheme for solving the above technical problems is as follows: a catalyst preparation method, the preparation method is:

[0008] S1, uniformly mix copper oxide and activated carbon, and place them in a sealed container to drive out the air in the system; according to a certain proportion, nitrogen and hydrogen chloride gas are filled, under the condition of heating, hydrogen chloride gas reacts with copper oxide to generate copper chloride and water, and the generated copper chloride is adsorbed on the activated carbon in water;

[0009] S2, continue to introduce nitrogen under the condition of heating, and take away the excess hydrogen chloride gas and the hydrogen chloride gas desorbed from the activated carbon;

[0010] S3, continue to introduce oxygen and nitrogen, oxidize the copper chloride to copper oxide, continue to introduce nitrogen to take away the excess oxygen and chlorine, and cool the system to room temperature, finally wash, dry, sieve, and microwave to obtain the activated carbon catalyst loaded with copper oxide.

[0011] Further, in step S1, the mass ratio of copper oxide to activated carbon is 1: (5-10);

[0012] The volume ratio of hydrogen chloride gas to nitrogen is 1: (6-10), the flow rate of HCl gas is 20-40 mL / min, and the flow rate of N2 is 120-400 mL / min;

[0013] In step S1, the heating condition is 180-220 DEG C.

[0014] Further, in step S2, the heating condition is 180-220 DEG C;

[0015] In step S3, the process of oxidizing copper chloride to copper oxide includes a low-temperature oxidation stage and a medium-temperature oxidation stage in sequence;

[0016] During the low-temperature oxidation stage, the gas introduced into the system includes 4.5%-5.5% of O2, 0.8%-1.2% of water vapor and 93.3%-94.7% of N2 in terms of volume percentage, wherein the water vapor is contained in N2, the total flow of the gas introduced during the low-temperature oxidation stage is 110-130 mL / min, the temperature is controlled at 220-240 DEG C, and the duration is 55-65 min;

[0017] During the medium-temperature oxidation stage, the gas introduced into the system includes 7.5%-8.5% of O2 and 91.5%-92.5% of N2 in terms of volume percentage, the total volume flow of the gas introduced during the medium-temperature oxidation stage is 140-160 mL / min, the flow rate of O2 is 10-14 mL / min, the flow rate of N2 is 126-150 mL / min, the temperature is controlled at 260-280 DEG C, and the duration is 15-25 min;

[0018] During the cooling to room temperature, pure N2 with a volume ratio of greater than or equal to 99.99% is introduced at a flow rate of 190-210 mL / min until the system is cooled to 20-30 DEG C.

[0019] Further, in step S3, the sieving obtains the activated carbon loaded with copper oxide with a mesh number of 30-50 meshes, and the activated carbon has a pore size of 2-50 nm and a specific surface area of greater than or equal to 1000 m² / g.

[0020] The microwave treatment is performed in a nitrogen environment, the microwave power is 500-700 W, the microwave treatment time is 5-20 min, the microwave treatment temperature is 120-150 DEG C, and during the microwave treatment, the nitrogen gas flow is continuously introduced, the nitrogen is introduced throughout the process, and after the microwave treatment, the nitrogen is continuously introduced for cooling for 10-15 min.

[0021] The application further discloses a decryption detection method of the chemical fiber encrypted by the metal oxide.

[0022] The to-be-tested chemical fiber is mixed with a catalyst, and then subjected to high-temperature decomposition treatment; then, the catalyst is removed by screening to obtain a solid powder; whether the solid powder contains metal ions is rapidly characterized by using a fluorescence agent; and the ion type and content are obtained by measuring a fluorescence emission spectrum. A combined detection strategy of "fluorescence spectroscopy as a main detection method and ICP-MS as an auxiliary verification" is adopted, and ICP-MS is used as a supplementary means for periodic verification of the accuracy of the main detection method or for quantitative analysis in special cases such as complex matrix, questionable results or trace metals. The advantages of the fluorescence spectrometer for detecting metal ions are: low cost, simple operation, convenient maintenance, fast response, and suitability for high-throughput screening and strong flexibility. For targeted monitoring of metal ions and verification of the effect of certain treatments, porphyrin fluorescence method combined with a fluorescence spectrometer is a completely reasonable and efficient choice. ICP-MS is complex to operate and has a long cycle, and is not suitable for large-scale rapid testing, but is only used for quantitative detection of trace elements, complex samples.

[0023] The catalyst is prepared according to the preparation method of the present application.

[0024] Further, in the high-temperature decomposition treatment, the mass ratio of the amount of the catalyst to the to-be-tested chemical fiber is (5-10):1, and the temperature of the high-temperature decomposition treatment is 400-550 ℃; the high-temperature decomposition treatment is carried out in an oxygen and nitrogen atmosphere, wherein the volume ratio of oxygen to nitrogen is (20-30):(80-70), and the total flow rate of oxygen and nitrogen is maintained at 200-400 mL / min.

[0025] Further, a 50-mesh sieve is used in the screening process, and the remaining solid powder with a small particle size is characterized by using a fluorescence agent.

[0026] Further, the fluorescence agent is a porphyrin fluorescence agent solution, the porphyrin fluorescence agent in the porphyrin fluorescence agent solution is a mixture of tetrakis(4-carboxyphenyl)porphyrin (TCPP), tetrakis(4-sulfonatophenyl)porphyrin (H2TSPP) and octaethylporphyrin (OEP) according to a mass ratio of 3:(4.5-5.5):(1.5-2.5), and the solvent in the porphyrin fluorescence agent solution is a mixed solvent of water, ethanol and dimethyl sulfoxide, wherein the volume ratio of water, ethanol and dimethyl sulfoxide (DMSO) is 5:(2.5-3.5):(1.5-2.5).

[0027] Further, the method for measuring the fluorescence emission spectrum is as follows: after the solid powder is dissolved in an acid solution, ultrasonic treatment and filtration are performed, then the fluorescence agent is added and the pH is adjusted, ultrasonic treatment is performed again, and then reaction is performed after standing, finally the sample to be measured is obtained by filtration, the fluorescence emission spectrum is measured using the sample to be measured, the fluorescence intensity and peak position data of different samples are recorded to realize qualitative and quantitative testing of metal elements; the fluorescence emission spectrum of the sample to be measured containing metal oxides and the blank control sample are compared, if the fluorescence intensity of the sample is obviously quenched or enhanced and is significantly different from the blank control sample, it is indicated that the metal oxides exist in the solid substance; and then according to the standard curve, the regression equation and the ultraviolet absorption spectrum, qualitative and quantitative testing of metal elements is realized.

[0028] Further, the fluorescence emission spectrum is measured using the sample to be measured, the fluorescence intensity and peak position data of different samples are recorded, and the metal type is determined by comparing with the known standard metal ion-porphyrin complex fluorescence spectrum; in addition, a standard curve and a regression equation (R 2 ≥0.99) of the relationship between the metal concentration and the fluorescence intensity are established; the fluorescence intensity of the unknown sample is substituted into the regression equation to calculate the metal concentration; if there is peak overlap, the ultraviolet absorption spectrum is used for identification; and qualitative and quantitative testing of metal elements is realized.

[0029] Further, the process conditions of ultrasonic treatment after the solid powder is dissolved in an acid solution are as follows: the ultrasonic treatment power is 190-210 W, ultrasonic treatment is first performed at 50-55 DEG C for 10-20 min to promote the dissolution of the metal oxides, then ultrasonic treatment is performed at 50-60 DEG C for 10-30 min to promote the dissolution and reaction, and then 0.22 mu m filter membrane filtration is performed to remove unsolved particles;

[0030] The process conditions of ultrasonic treatment after the fluorescence agent is added and the pH is adjusted are as follows: the ultrasonic treatment power is 140-160 W, ultrasonic treatment is first performed at 23-28 DEG C for 5-10 min, then ultrasonic treatment is performed at 50-60 DEG C for 10-30 min, the whole ultrasonic process is performed in the dark to avoid the structure of the fluorescence agent being damaged, then the reaction is performed in the dark for 20-40 min, 0.22 mu m filter membrane filtration is performed to remove unsolved particles, and the clear porphyrin fluorescence agent-metal ion reaction solution, i.e., the sample to be measured, is obtained.

[0031] The beneficial effects of the present application are as follows:

[0032] The detection method can quickly and accurately identify the type and content of metal oxides in chemical fibers. In the detection method, the presence of metal elements can be determined by using fluorescent markers first, and whether tracking can be performed. The tracking method is also fast and accurate, and is a complete set of equipment, which is simple to operate. The present application can detect the type and content of metal oxides, and can distinguish chemical fibers containing metal oxide anti-counterfeit tracking. The detection method can be used as an identification method for recycling chemical fibers. The detection method can quickly and accurately locate the batch and manufacturer of the fiber according to the anti-counterfeit code, facilitate the viewing of the flow process and results of different batches of fibers, and prevent others from counterfeiting. For example: the type and content of the anti-counterfeit substance can be used to determine which fiber it is, whether it meets the use requirements, and whether it is true or false. Anti-counterfeit elements can be added to the fibers to be recycled, and recycling can be achieved after the finished product is made, realizing resource recycling.

[0033] In the detection method, the copper oxide-loaded activated carbon catalyst can catalyze the decomposition process and absorb the additional products of fiber decomposition (such as oil, gas, water, etc. produced during the decomposition of chemical fibers) during the fiber decomposition process, so that other substances produced during the decomposition of chemical fibers do not affect the detection process. It is helpful for the next step of preliminary identification of the presence of metal oxides by using fluorescent agents, and it is also beneficial for further use of a fluorescence spectrometer to determine the type and content of metals, so that the metal oxide tracking agent added to the chemical fibers can be clearly selected.

[0034] In the detection method, a combination detection strategy of "fluorescence spectroscopy as the main detection method plus ICP-MS as the auxiliary verification" is adopted. Fluorescence spectroscopy is simple to operate, low in cost, and fast in response. ICP-MS is used as a supplementary means for periodic verification of the accuracy of the main detection method, or for quantitative analysis in special cases such as complex matrix, suspicious results, or trace metals. DETAILED DESCRIPTION

[0035] The specific embodiments of the present application will be described in detail below. The present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms used are only for describing specific embodiments and are not intended to limit the present application.

[0037] A preparation method of a catalyst, the preparation method is:

[0038] S1, after mixing copper oxide and activated carbon uniformly, placing in airtight container, filling in high-purity nitrogen (≥99.99%), driving out air in the system; according to certain proportion, filling in nitrogen and hydrogen chloride gas, under heating condition, hydrogen chloride gas reacts with copper oxide, generating copper chloride and water, and the generated copper chloride is adsorbed on activated carbon in water; the essence of the reaction is that hydrogen chloride gas reacts with copper oxide under heating condition, generating copper chloride and water. In the reaction, hydrogen chloride as acidic gas combines with basic oxide copper oxide, hydrogen element combines with oxygen element in copper oxide to form water, and chlorine element combines with copper element to generate copper chloride, with the reaction proceeding, black copper oxide solid gradually reduces, and blue-green copper chloride is generated, when there is no black copper oxide, it proves that copper chloride has been generated completely.

[0039] S2, under heating condition, continuing to pass in nitrogen (the flow rate of nitrogen is 100 mL / min-200 mL / min, and the duration is 20 min-30 min), taking away excess hydrogen chloride gas and hydrogen chloride gas desorbed from activated carbon, ensuring the purity of activated carbon and copper chloride surface.

[0040] S3, continuing to pass in oxygen and nitrogen, oxidizing copper chloride into copper oxide, continuing to pass in nitrogen to take away excess oxygen and chlorine, and cooling the system to room temperature (the chlorine taken away is hydrogen fluoride acid grade tail gas absorption device, avoiding environmental pollution), finally, through washing, drying, sieving and microwave treatment, the activated carbon catalyst loaded with copper oxide is obtained.

[0041] Specifically, in step S1, the mass ratio of copper oxide and activated carbon is 1: (5-10).

[0042] Preferably, the mass ratio of copper oxide and activated carbon is 1:10.

[0043] More specifically, the activated carbon catalyst used has a pore size of 2-50 nm (nanometer), belongs to mesoporous structure, and has a high specific surface area (≥1000 m² / g).

[0044] Specifically, the volume ratio of hydrogen chloride gas and nitrogen is 1: (6-10) (the gas source environment temperature is 10℃-40℃); the flow rate of HCl gas is 20-40 mL / min, and the flow rate of N2 is 120-400 mL / min; the specific operation is: first passing nitrogen to replace → passing HCl gas after stabilization → maintaining for 30 minutes; using hydrogen fluoride acid grade tail gas absorption device to capture HCl / Cl2, maintaining the system in a slight positive pressure.

[0045] In step S1, the heating condition is 180-220℃.

[0046] Specifically, in step S2, the heating condition is 180-220℃.

[0047] In step S3, the process of oxidizing copper chloride to copper oxide includes a low-temperature oxidation stage and a medium-temperature oxidation stage in sequence;

[0048] In the low-temperature oxidation stage, the gas introduced into the system includes 4.5%-5.5% of O2, 0.8%-1.2% of water vapor and 93.3%-94.7% of N2 in terms of volume percentage, wherein the water vapor is contained in N2, the total flow rate of the gas introduced in the low-temperature oxidation stage is 110-130 mL / min, the temperature is controlled at 220-240 ℃, and the duration is 55-65 min;

[0049] In the medium-temperature oxidation stage, the gas introduced into the system includes 7.5%-8.5% of O2 and 91.5%-92.5% of N2 in terms of volume percentage, the total volume flow rate of the gas introduced in the medium-temperature oxidation stage is 140-160 mL / min, the flow rate of O2 is 10-14 mL / min, the flow rate of N2 is 126-150 mL / min, the temperature is controlled at 260-280 ℃, and the duration is 15-25 min; the moderate temperature rise and the increase of oxygen concentration in the medium-temperature oxidation stage ensure the completion of the reaction and the efficient generation of CuO.

[0050] In the process of cooling to room temperature, pure N2 with a volume ratio of ≥99.99% is introduced at a flow rate of 190-210 mL / min until the system is cooled to 20-30 ℃. In each stage, the temperature, gas composition and flow rate are controlled by gradient to balance the reaction efficiency and product stability and ensure the process repeatability. In the whole process, the water vapor and the gases are controlled by a gas mass flow controller.

[0051] Preferably, in steps S1 and S2, the heating condition is 200 ℃.

[0052] Specifically, in step S3, the sieved activated carbon loaded with copper oxide has a mesh number of 30-50.

[0053] In the microwave treatment, the microwave power is 500-700 W, the microwave treatment time is 5-20 min, and the microwave treatment temperature is 120-150 ℃.

[0054] Preferably, the sieved activated carbon loaded with copper oxide has a mesh number of 40.

[0055] More specifically, in step S3, the specific operation of microwave treatment is: using deionized water to wash the activated carbon multiple times until the filtrate is free of Cl⁻ reaction (AgNO3 test); the drying condition is: drying at a temperature of 105°C for 12 hours to remove moisture, and using a fixed sieve to screen particles of a suitable particle size range (30-50 mesh) to ensure that the catalyst is uniformly heated during microwave treatment and uniformly adhered to the fiber surface. According to the characteristics of the catalyst, the microwave power is selected to be between 500-700 watts, the treatment time is 5-20 minutes, and the treatment temperature is controlled at 120-150 ℃. During microwave treatment, the gas flow rate is controlled at 50 mL / min under a nitrogen atmosphere. Before microwave treatment, nitrogen should be passed in for 10 minutes to exhaust the residual oxygen in the system and ensure the formation of a stable inert atmosphere. During microwave treatment, nitrogen is continuously passed in to maintain an inert environment throughout the process. After treatment, continue to pass in nitrogen to cool for 10-15 minutes with a temperature ≤ 60°C to prevent the backflow of oxygen under heat, which can cause carbon oxidation. The pressure requirement is normal pressure or slight positive pressure (+0.8 kPa). The pretreated catalyst is placed in a quartz glass vessel and placed in a microwave reactor. The microwave device is turned on, the nitrogen environment is maintained, and the treatment is carried out according to the set parameters. After treatment, continue to pass in nitrogen to allow the catalyst to cool naturally in the microwave reactor to room temperature.

[0056] A decryption detection method for chemical fibers encrypted using metal oxides, the detection method being:

[0057] After the to-be-tested chemical fibers (chemical fibers containing metal oxides) are uniformly mixed with the catalyst, they are placed in a porous high-temperature-resistant ceramic pot in a sealed container filled with a certain proportion of oxygen and nitrogen. The pot bottom has a space for air and heat circulation. After high-temperature decomposition, the catalyst not only accelerates the decomposition of the chemical fibers, but also adsorbs the oil, gas, water, etc. produced during the decomposition of the chemical fibers. The remaining solid substances are sieved through a 50-mesh sieve, and the remaining solid powders with small particle sizes are characterized by a fluorescence agent. The fluorescence agent is used to quickly characterize whether the solid powders contain metal ions. The ion species and content are obtained by measuring the fluorescence emission spectrum. The combination detection strategy of "the main detection method is fluorescence spectroscopy plus ICP-MS auxiliary verification" is adopted. ICP-MS is used as a supplementary means for periodic verification of the accuracy of the main detection method, or for quantitative analysis in special cases such as complex matrix, questionable results, or trace metals.

[0058] The catalyst is prepared according to the preparation method of the present application.

[0059] Specifically, the amount of catalyst used in the high-temperature decomposition process is (5-10):1 by mass ratio to the chemical fiber to be tested, and the temperature of the high-temperature decomposition process is 400-550℃. The high-temperature decomposition process is carried out in an oxygen and nitrogen atmosphere, and the volume ratio of oxygen to nitrogen is (20-30):(80-70). The total flow rate of oxygen and nitrogen is maintained at 200-400 mL / min.

[0060] Preferably, the amount of catalyst used in the high-temperature decomposition process is 8:1 by mass ratio to the chemical fiber to be tested, the volume ratio of oxygen to nitrogen is 25:75, the total flow rate is set to 300 mL / min, and the temperature is adjusted within the range of 400-550℃ according to the fiber condition.

[0061] Specifically, the screening process uses a 50-mesh sieve, and the remaining solid powder with a small particle size is characterized by a fluorescent agent.

[0062] Specifically, the fluorescent agent is a porphyrin fluorescent agent solution, and the porphyrin fluorescent agent in the porphyrin fluorescent agent solution is a mixture of tetra(4-carboxyphenyl)porphyrin, tetra(4-sulfonic acid phenyl)porphyrin, and octaethylporphyrin in a mass ratio of 3:(4.5-5.5):(1.5-2.5). The solvent in the porphyrin fluorescent agent solution is a mixed solvent of water, ethanol, and dimethyl sulfoxide, and the volume ratio of water, ethanol, and DMSO is 5:(2.5-3.5):(1.5-2.5).

[0063] Preferably, the mass ratio of tetra(4-carboxyphenyl)porphyrin, tetra(4-sulfonic acid phenyl)porphyrin, and octaethylporphyrin is 3:5:2, and the volume ratio of water, ethanol, and DMSO is 5:3:2.

[0064] Specifically, the method for determining the fluorescence emission spectrum is as follows: the solid powder is dissolved in an acid solution, ultrasonically treated and filtered, then mixed with a fluorescent agent, adjusted to a certain pH, ultrasonically treated again, allowed to stand for reaction, and finally filtered to obtain a sample to be tested. The fluorescence emission spectrum is measured using the sample to be tested, and the fluorescence intensity and peak position data of different samples are recorded. By comparing with the known standard metal ion-porphyrin complex fluorescence spectrum, the type of metal can be determined. A standard curve is established by plotting the "metal concentration-fluorescence intensity" standard line. The fluorescence intensity of the unknown sample is substituted into the regression equation to calculate the metal concentration. If there is spectral peak overlap, ultraviolet absorption spectrum is used for resolution to achieve qualitative and quantitative testing of metal elements.

[0065] Specifically, the pH is adjusted to 2.5±0.2, 5±0.2, or 7.5±0.2.

[0066] The used ultrasonic equipment is a constant temperature water bath ultrasonic cleaning machine, and the process conditions of ultrasonic treatment (first ultrasonic treatment) after the solid powder is dissolved in an acid solution are as follows: the ultrasonic treatment power is 190-210 W, ultrasonic treatment is first carried out at 50-55 DEG C for 10-20 min to promote the dissolution of the metal oxide, and then ultrasonic treatment is carried out at 50-60 DEG C for 10-30 min to promote the dissolution and reaction, and then 0.22 μm filter membrane filtration is carried out to remove unsolved particles;

[0067] The process conditions of ultrasonic treatment (second ultrasonic treatment) after adding a fluorescent agent and adjusting pH are as follows: the ultrasonic treatment power is 140-160 W, ultrasonic treatment is first carried out at 23-28 DEG C for 5-10 min, and then ultrasonic treatment is carried out at 50-60 DEG C for 10-30 min, the whole ultrasonic process is carried out in the dark to avoid the destruction of the structure of the fluorescent agent, and then the solution is placed in the dark for 20-40 min, 0.22 μm filter membrane filtration is carried out to remove unsolved particles, and a clear porphyrin fluorescent agent-metal ion reaction solution is obtained, which is the sample to be detected.

[0068] More specifically, the acid solution for dissolving the solid powder is a citric acid aqueous solution with a concentration of 0.2 mol / L, that is, after the solid powder is dissolved in the citric acid aqueous solution with a concentration of 0.2 mol / L, the fluorescent agent is added, and then the pH is adjusted to 2.5±0.2 by using a formic acid-TEA aqueous solution with a concentration of 0.1 mol / L, or the pH is adjusted to 5±0.2 by using an acetic acid-sodium acetate buffer solution (aqueous solution) with a concentration of 0.05 mol / L, or the pH is adjusted to 7.5±0.2 by using a Tris-HCl buffer solution (aqueous solution) with a concentration of 0.05 mol / L. The detection system of the metal ion adopts the operation sequence of first adding the porphyrin mixed solution and then adjusting the pH, because the porphyrin fluorescent probe (TCPP, TSPP, OEP) has good pH stability in structure, and the fluorescence response depends on the complexing efficiency with the metal ion, and the complexing process is highly dependent on the pH condition of the system.

[0069] More specifically, in the embodiment of the present application, the metal oxide needs to be quantitatively detected, and a standard curve needs to be prepared, and the method for preparing the standard curve is as follows:

[0070] Dissolve the metal oxide (which can be used as a chemical fiber anti-counterfeit mark) in a citric acid solution.

[0071] Preparation of metal ion standard solution: prepare each known metal ion citrate aqueous solution (such as copper citrate, zinc citrate, molybdenum citrate, zirconium citrate, strontium citrate, germanium citrate, vanadium citrate, chromium citrate, manganese citrate, iron citrate, cobalt citrate, nickel citrate, aluminum citrate, magnesium citrate, calcium citrate or barium citrate), wherein the concentration of each metal ion in the aqueous citrate solution is 1 mol / L, and each metal ion citrate aqueous solution is diluted with water to obtain samples with the following concentrations: 5, 10, 50, 100 μmol / L. For each concentration, 3 samples of 2 mL are taken in parallel, and 1.5 mL of fluorescent agent (the concentration of porphyrin fluorescent agent in the fluorescent agent is 300 μmol / L, TCPP:TSPP:OEP = 3:5:2) is added to each sample to obtain a mixed solution, buffer is added, the pH range of the corresponding metal is adjusted, and deionized water is added to a volume of 10 mL.

[0072] The specific method for adding buffer is as follows: the pH of the three parallel samples is adjusted to 2.5±0.2, 5±0.2 and 7.5±0.2, respectively, by adding different buffers. That is, 0.1 mol / L formic acid-TEA aqueous solution is added to the first sample to adjust the pH to 2.5±0.2; 0.05 mol / L acetic acid-sodium acetate buffer (aqueous solution) is added to the second sample to adjust the pH to 5±0.2; and 0.05 mol / L Tris-HCl buffer (aqueous solution) is added to the third sample to adjust the pH to 7.5±0.2. After adjusting the pH, deionized water is added to each sample to a volume of 10 mL; avoid light and react for 25-30 min (20-30°C).

[0073] Using a fluorescence spectrometer, the emission wavelength is scanned, the maximum fluorescence emission peak intensity is recorded, the horizontal axis is the metal ion concentration, the vertical axis is the fluorescence intensity, the standard curve is drawn, the linear regression equation is obtained, and the R² of the linear regression equation is ≥0.99. For each concentration, 3 parallel samples are prepared, and the average value is calculated.

[0074] A plurality of metal ion standard curves (fluorescence response of each metal at multiple concentrations) are established; and they are used as a training set.

[0075] A prediction model is established by multiple linear regression (MLR); the spectrum of the mixed metal sample is input into the model, and the concentration components of each metal are analyzed.

[0076] II. Setting of blank control samples:

[0077] Blank 1: porphyrin solution + solvent (without metal ions);

[0078] The solvent is water-ethanol-dimethyl sulfoxide (volume ratio is 5:3:2), the concentration of the porphyrin solution is 300 μmol / L (the porphyrin in the porphyrin solution is tetra (4-carboxyphenyl) porphyrin, tetra (4-sulfonic acid phenyl) porphyrin and octaethyl porphyrin, and the mass ratio is 3:5:2), the amount of the porphyrin solution used for preparing each blank 1 sample is 1.5 mL, each blank 1 sample is finally diluted to 10 mL with the solvent, each blank 1 sample is further ultrasonically treated: the time is 8 minutes, the power is 150 W, and the temperature is controlled at 25 °C, then the ultrasonic treatment is further carried out at 50 °C for 15 minutes, then the sample is placed in dark for 30 minutes, then the sample is filtered through a 0.22 μm filter membrane to remove unsolved particles, and a clear reaction solution is obtained, which is the blank 1-1, blank 1-2, blank 1-3 sample to be tested, and the fluorescence spectrum is tested. The specific distinction of each blank 1 sample is as follows, which is taken as a blank control sample.

[0079] The grouping design of the blank 1 is as follows.

[0080] The blank 1-1 (formic acid-TEA group): 1.5 mL of the porphyrin solution is taken, formic acid-TEA buffer is added to adjust the pH to 2.5±0.2, and then the solvent is added to make the volume 10 mL.

[0081] The blank 1-2 (acetic acid-sodium acetate group): 1.5 mL of the porphyrin solution is taken, acetic acid-sodium acetate buffer is added to adjust the pH to 5±0.2, and then the solvent is added to make the volume 10 mL.

[0082] The blank 1-3 (Tris-HCl group): 1.5 mL of the porphyrin solution is taken, Tris-HCl buffer is added to adjust the pH to 7.5±0.2, and then the solvent is added to make the volume 10 mL.

[0083] The blank 2 is as follows.

[0084] The strong fluorescence quenching group aqueous solution, the weak fluorescence / scattering group aqueous solution and the alkaline earth metal group aqueous solution are respectively prepared.

[0085] The composition of the strong fluorescence quenching group aqueous solution is: copper citrate, iron citrate, cobalt citrate and water, the molar ratio of the copper citrate, the iron citrate and the cobalt citrate is 1:1:1; three concentration solutions are prepared by adjusting the amount of water added, and the total metal ion concentration in the three concentration solutions is 10, 50 and 100 μmol / L respectively; in addition, three samples are prepared for each concentration solution.

[0086] The composition of the weak fluorescence / scattering group aqueous solution is: zinc citrate, manganese citrate, nickel citrate, and water, wherein the molar ratio of zinc citrate, manganese citrate, and nickel citrate is 1:1:1; by adjusting the amount of water added, three concentrations of solutions are prepared, wherein the total metal ion concentration in the three concentrations of solutions is 10, 50, 100 μmol / L respectively; in addition, 3 parallel solutions are prepared for each concentration.

[0087] The composition of the alkaline earth metal group aqueous solution is: magnesium citrate, calcium citrate, barium citrate, and water, wherein the molar ratio of magnesium citrate, calcium citrate, and barium citrate is 1:1:1; by adjusting the amount of water added, three concentrations of solutions are prepared, wherein the total metal ion concentration in the three concentrations of solutions is 10, 50, 100 μmol / L respectively; in addition, 3 parallel solutions are prepared for each concentration.

[0088] The above prepared solutions are used to deduct background fluorescence. After the above solutions are prepared, ultrasonic treatment is performed: 15 minutes, 200W, temperature control at 55℃, then ultrasonic treatment at 55℃ for 20 minutes, 0.22 μm filter membrane filtration is performed to remove unsolved particles. Clear metal ion solution is obtained, which is then subjected to the following treatment.

[0089] The above prepared solutions of each concentration are referred to as citrate aqueous solutions, and the citrate aqueous solutions are subjected to subsequent grouping design.

[0090] The grouping design of blank 2 is as follows:

[0091] Blank 2-1 (formic acid-TEA group): take 2 mL of the metal ion citrate aqueous solution, add formic acid-TEA buffer to adjust the pH to 2.5±0.2, and add solvent to make up to 10 mL.

[0092] Blank 2-2 (acetic acid-sodium acetate group): take 2 mL of the metal ion citrate aqueous solution, add acetic acid-sodium acetate buffer to adjust the pH to 2.5±0.2, and add solvent to make up to 10 mL.

[0093] Blank 2-3 (Tris-HCl group): take 2 mL of the metal ion citrate aqueous solution, add Tris-HCl buffer to adjust the pH to 2.5±0.2, and add solvent to make up to 10 mL.

[0094] After each blank 2 sample is prepared, ultrasonic treatment is performed: time 8 minutes, 150W, temperature control at 25℃, then ultrasonic treatment at 50℃ for 15 minutes, then light shielding and standing for 30 min at a temperature condition of 25℃, 0.22 μm filter membrane filtration is performed to remove unsolved particles, and clear reaction solution is obtained.

[0095] The effects and use methods of the blank control group are as follows:

[0096] The role of blank 1: determine the fluorescence signal of porphyrin under different pH conditions alone as the "reagent background value". If porphyrin itself has fluorescence at the detection wavelength, it can be deducted by blank 1 to avoid misjudgment as the signal of "metal-porphyrin complex".

[0097] The role of blank 2: for the solutions composed of three types of metal ions, strong fluorescence quenching group aqueous solution, weak fluorescence / scattering group aqueous solution, and alkaline earth metal group aqueous solution, determine their fluorescence signals under different pH (2.5±0.2, 5±0.2, 7.5±0.2) and different total concentrations (10, 50, 100 μmol / L, the ions in the group are mixed in a molar ratio of 1:1:1, and the single ion concentration is 10 / 3, 50 / 3, 100 / 3 μmol / L, respectively) as the "matrix background value". Through blank 2, the specific interference of metal ions (and citrate, buffer) on fluorescence detection can be excluded (such as fluorescence quenching effect of strong quenching group, scattering signal of weak fluorescence group, baseline fluctuation of alkaline earth metal group, etc.).

[0098] Actual use method: when correcting the fluorescence signal of the sample to be tested (metal ion-porphyrin reaction solution), the fluorescence spectrum needs to be determined first to preliminarily judge the group of metal ions in the sample (strong fluorescence quenching group, weak fluorescence / scattering group, or alkaline earth metal group), and then the following formula is used for calculation:

[0099] Corrected signal = fluorescence signal of sample to be tested - sample signal of blank 1 under the same pH - sample signal of blank 2 under the same concentration and pH of the corresponding group.

[0100] Through this correction, it can be ensured that the final signal only reflects the "complexation reaction of metal ions and porphyrin", effectively eliminates the specific background interference of different types of metal ions, significantly improves the accuracy and reliability of quantitative analysis, and provides a scientific basis for metal element concentration calculation.

[0101] The analysis stage includes the following processes:

[0102] Analysis of the results of testing the fluorescence emission spectrum: compare with the known standard fluorescence spectrum of metal-porphyrin complex to determine the type of metal ion; if there is peak overlap, use ultraviolet absorption spectrum for secondary confirmation; after preliminary judgment of the type of metal, use the standard solution of the metal to draw a standard curve of fluorescence intensity-concentration according to its type;

[0103] Quantitative regression calculation: correspond the fluorescence intensity in the unknown sample to the standard curve, and calculate the actual metal ion concentration by regression.

[0104] Primary screening spectrum library: a database of standard peak spectrum of fluorescence used in the laboratory is established. For uncertain elements, when it is necessary to periodically verify the accuracy of the main detection method, or for quantitative analysis in special cases such as complex matrix, questionable results or trace metals, ICP-MS testing is added.

[0105] Example 1

[0106] Take 32 g of meta-aramid fiber as a chemical fiber, and it is known that the metal oxide in the chemical fiber contains 0.0196 g, among which the aluminum ion is 6.22 mg, the calcium ion is 2.80 mg, and the zinc ion is 3.15 mg. The metal oxide in the chemical fiber is detected according to the following method steps:

[0107] (1) The specific process conditions for preparing copper oxide-loaded activated carbon catalyst are as follows: the mass ratio of copper oxide to activated carbon is 1:10, the volume ratio of hydrogen chloride gas to nitrogen gas is 1:8, and the reaction temperature of hydrogen chloride gas with copper oxide is 200°C (the gas source environment temperature is 25°C); the flow rate of HCl gas is 30 mL / min, and the flow rate of N2 is 240 mL / min; the specific operation is as follows: first, replace with nitrogen gas → stabilize → introduce HCl gas → maintain for 30 minutes; use a hydrofluoric acid grade tail gas absorption device to capture HCl / Cl2, and maintain a slight positive pressure in the system.

[0108] Under the condition of 200°C, nitrogen gas is introduced to carry away the excess hydrogen chloride gas and the hydrogen chloride gas desorbed from the activated carbon; then oxygen and nitrogen gas are continuously introduced to oxidize copper chloride to copper oxide, and the process of oxidizing copper chloride to copper oxide includes a low-temperature oxidation stage and a medium-temperature oxidation stage in sequence;

[0109] During the low-temperature oxidation stage, the gas introduced into the system includes 5% O2, 1% water vapor, and 94% N2 in terms of volume percentage, wherein the water vapor is contained in N2, the total flow rate of the gas introduced during the low-temperature oxidation stage is 120 mL / min, the temperature is controlled at 230°C, and the duration is 60 min;

[0110] During the medium-temperature oxidation stage, the gas introduced into the system includes 8% O2 and 92% N2 in terms of volume percentage, the total volume flow rate of the gas introduced during the medium-temperature oxidation stage is 150 mL / min, the flow rate of O2 is 12 mL / min, the flow rate of N2 is 128 mL / min, the temperature is controlled at 270°C, and the duration is 20 min.

[0111] Then, nitrogen gas is continuously introduced to carry away the excess oxygen and chlorine and cool the system to room temperature of 25°C, and during the cooling process, pure N2 with a volume ratio of ≥99.99% is introduced at a flow rate of 200 mL / min.

[0112] Washing the activated carbon with deionized water multiple times until the filtrate is free of Cl⁻(AgNO3 test); drying temperature 105°C, drying time 12 hours or vacuum drying to remove moisture. Finally, 260 g of the catalyst is selected for microwave treatment.

[0113] The conditions for microwave treatment are: using a fixed sieve to screen particles of a suitable particle size range (40 mesh) to ensure uniform heating of the catalyst during microwave treatment and more uniform adhesion to the fiber surface. According to the characteristics of the catalyst, the microwave power is selected to be 600 watts, the treatment time is 12 minutes, and the treatment temperature is controlled at 140°C. The pretreated catalyst is placed in a quartz glass vessel and placed in a microwave reactor. The microwave device is turned on and a nitrogen environment is maintained. The treatment is carried out according to the set parameters. After the treatment is completed, the nitrogen is continued to be introduced and the catalyst is naturally cooled to room temperature in the microwave reactor.

[0114] Finally, 256 g of the catalyst is selected, with a mass ratio of 8:1 to the chemical fiber.

[0115] (2) Mix the meta-aramid fiber with the catalyst in an environment with a volume ratio of oxygen to nitrogen of 25:75, and completely decompose at 500°C. Screen the remaining solid material through a 50 mesh sieve. Particles below 50 mesh are metal oxides, approximately 0.0198 g (to be tested metal oxides).

[0116] (3) Prepare a porphyrin solution: select four (4-carboxyphenyl) porphyrin (TCPP), four (4-sulfonic acid phenyl) porphyrin (H2TSPP), and octaethyl porphyrin (OEP) with a mass ratio of 3:5:2. The solvent is a mixture of water-ethanol-dimethyl sulfoxide (DMSO) with a volume ratio of water:ethanol:DMSO = 5:3:2. The concentration of porphyrin in the porphyrin solution is 300 μmol / L.

[0117] Prepare the salt of the metal oxide to be tested: dissolve the metal oxide from step (2) with 12 mL of 0.2 mol / L citric acid solution. First ultrasonic (dissolution stage): 15 minutes, 200W, 55°C. Then ultrasonic treatment at 55°C for 20 minutes. Filter through a 0.22 μm filter membrane to remove undissolved particles. The clear filtrate obtained is the metal ion solution.

[0118] Take 3 samples of 2 mL each from the above filtrate:

[0119] Add 1.5 mL of porphyrin solution (300 μmol / L, TCPP:TSPP:OEP = 3:5:2) to each of the above samples;

[0120] Three samples were added to three different pH buffers, and the specific operation was as follows: 1 mL of 0.1 mol / L formic acid-TEA aqueous solution was added to the first sample to adjust the pH to 2.5; 1 mL of 0.05 mol / L acetic acid-sodium acetate buffer (aqueous solution) was added to the second sample to adjust the pH to 5; and 1 mL of 0.05 mol / L Tris-HCl buffer (aqueous solution) was added to the third sample to adjust the pH to 7.5.

[0121] Volume adjustment: 10 mL of water was added to each of the above three samples, and the second ultrasonic treatment (after mixing the fluorescent agent): the time was shortened to 8 minutes, 150 W, and the temperature was controlled at 25°C. Then, ultrasonic treatment was performed at 50°C for 15 minutes, followed by dark storage for 30 minutes at 25°C. The reaction solution was filtered through a 0.22 μm filter to remove undissolved particles, and a clear porphyrin fluorescent agent-metal ion reaction solution was obtained, which was the sample to be tested.

[0122] Fluorescence emission spectrum test: the results were analyzed, and the fluorescence spectrum of the blank control sample was compared to determine whether there was a metal element. The metal ion species were determined by comparing with the known metal-porphyrin complex standard fluorescence spectrum. If the peaks overlap, the ultraviolet absorption spectrum is used for secondary confirmation. After the initial determination of the metal species, the standard solution of the metal was used to draw the fluorescence intensity-concentration standard curve according to the type of the metal.

[0123] Quantitative regression calculation: the fluorescence intensity of the unknown sample was corresponded to the standard curve, and the actual metal concentration was calculated by regression.

[0124] Preliminary screening spectrum library: a fluorescence standard peak graph database used in the laboratory was established.

[0125] The mass content of each element actually tested is shown in Table 1. The data in Table 1 is the result of volume adjustment to 10 mL, wherein ND means not detected, and the detection limit is 1 ppm.

[0126] Table 1 Determination results of Example 1

[0127]

[0128] As can be seen from the above table, the meta-aramid fiber contains trace elements of aluminum, calcium and zinc. As can be seen from the above, the mass deviation of the metal oxide is 1.0%, and the content of the above-mentioned aluminum, calcium and zinc in the metal oxide at the beginning is 1.6%, 1.2% and 1.9%, respectively.

[0129] Example 2

[0130] Take 32 g meta-aramid fiber as chemical fiber, it is known that the metal oxide in the chemical fiber contains 0.0196 g, among which the aluminum ion is 6.22 mg, the calcium ion is 2.80 mg, and the zinc ion is 3.15 mg. The metal oxide in the chemical fiber is detected according to the following method steps:

[0131] (1) The specific process conditions for preparing the activated carbon catalyst loaded with copper oxide are as follows: the mass ratio of copper oxide to activated carbon is 1:10, the volume ratio of hydrogen chloride gas to nitrogen is 1:8, and the reaction temperature of hydrogen chloride gas with copper oxide is 200°C (the gas source environment temperature is 25°C); the flow rate of HCl gas is 30 mL / min, and the flow rate of N2 is 240 mL / min; the specific operation is as follows: first, replace with nitrogen gas→stabilize→introduce HCl gas→maintain for 30 minutes; use a hydrogen fluoride grade tail gas absorption device to capture HCl / Cl2, and maintain a slight positive pressure in the system.

[0132] Under the condition of 200°C, nitrogen gas is introduced to carry away the excess hydrogen chloride gas and the hydrogen chloride gas desorbed from the activated carbon; then oxygen and nitrogen are continuously introduced to oxidize copper chloride to copper oxide, and the process of oxidizing copper chloride to copper oxide includes a low-temperature oxidation stage and a medium-temperature oxidation stage in sequence;

[0133] During the low-temperature oxidation stage, the gas introduced into the system includes 5% O2, 1% water vapor, and 94% N2 in terms of volume percentage, wherein the water vapor is contained in N2, the total flow rate of the gas introduced during the low-temperature oxidation stage is 120 mL / min, the temperature is controlled at 220°C, and the duration is 60 min;

[0134] During the medium-temperature oxidation stage, the gas introduced into the system includes 8% O2 and 92% N2 in terms of volume percentage, the total volume flow rate of the gas introduced during the medium-temperature oxidation stage is 150 mL / min, the flow rate of O2 is 12 mL / min, the flow rate of N2 is 128 mL / min, the temperature is controlled at 270°C, and the duration is 20 min.

[0135] Continue to introduce nitrogen to carry away the excess oxygen and chlorine and cool the system to room temperature 25°C, during which pure N2 with a volume ratio of ≥99.99% is introduced at a flow rate of 200 mL / min.

[0136] Wash the activated carbon with deionized water multiple times until the filtrate is free of Cl⁻ reaction (AgNO3 test); dry at a temperature of 105°C for 12 hours or vacuum dry to remove moisture. Finally, select 260 g of the catalyst for microwave treatment.

[0137] The conditions of microwave treatment are as follows: the particles with a proper particle size range are screened by using a fixed sieve (40 mesh) to ensure that the catalyst is uniformly heated during the microwave treatment and is more beneficial to be uniformly adhered to the surface of the fiber. According to the characteristics of the catalyst, the microwave power is selected to be 600 W, the treatment time is 12 minutes, and the treatment temperature is controlled at 140 DEG C. The pretreated catalyst is placed in a quartz glass container and placed in a microwave reactor. The microwave device is turned on, and the nitrogen environment is maintained. The treatment is carried out according to the set parameters. After the treatment is completed, the nitrogen is continuously introduced, and the catalyst is naturally cooled to room temperature in the microwave reactor.

[0138] Finally, 256 g of the catalyst is selected, and the mass ratio of the chemical fiber to the catalyst is 8:1.

[0139] (2) The meta-aramid fiber is mixed with the catalyst in an environment with a volume ratio of oxygen to nitrogen of 20:70, and is completely decomposed at a high temperature of 400 DEG C. The remaining solid substances are screened through a 50 mesh sieve. The particles below 50 mesh belong to metal oxides, and the mass of the metal oxides is about 0.0211 g (to be tested).

[0140] (3) Preparation of porphyrin solution: three kinds of tetra (4-carboxyphenyl) porphyrin (TCPP), tetra (4-sulfonic acid phenyl) porphyrin (H2TSPP) and octaethyl porphyrin (OEP) are selected, and the mass ratio is 3:5:2. The solvent is a mixed solvent of water-ethanol-dimethyl sulfoxide (DMSO), and the ratio is water: ethanol: DMSO = 5:3:2 (volume ratio). The concentration of porphyrin in the porphyrin solution is 300 μmol / L.

[0141] Preparation of salt of metal oxide to be tested: the metal oxide in step (2) is dissolved with 12 mL of 0.2 mol / L citric acid solution. The first ultrasonic treatment (dissolution stage) is carried out at 190 W and 50 DEG C for 10 minutes. Then, the ultrasonic treatment is carried out at 50 DEG C for another 10 minutes. The solution is filtered through a 0.22 μm filter membrane to remove undissolved particles. The clear filtrate obtained is the metal ion solution.

[0142] Three samples are taken from the above filtrate, each with a volume of 2 mL:

[0143] 1.5 mL of porphyrin solution (300 μmol / L, TCPP:TSPP:OEP = 3:5:2) is added to each of the above samples;

[0144] Three samples were added to three different pH buffers, and the specific operation was as follows: 1 mL of 0.1 mol / L formic acid-TEA aqueous solution was added to the first sample to adjust the pH to 2.5; 1 mL of 0.05 mol / L acetic acid-sodium acetate buffer (aqueous solution) was added to the second sample to adjust the pH to 5; and 1 mL of 0.05 mol / L Tris-HCl buffer (aqueous solution) was added to the third sample to adjust the pH to 7.5.

[0145] Volume adjustment: 10 mL of water was added to each of the above three samples, and the second ultrasonic treatment (after mixing the fluorescent agent) was performed for 5 minutes at 140 W, with the temperature controlled at 23°C. Then, the samples were ultrasonically treated at 50°C for 10 minutes, and then were kept in the dark for 30 minutes at 25°C. The samples were filtered through a 0.22 μm filter to remove the undissolved particles, and the clear porphyrin fluorescent agent-metal ion reaction solution was obtained, which was the sample to be tested.

[0146] Test of the fluorescence emission spectrum: the results were analyzed, and the fluorescence spectrum of the blank control sample was compared to determine whether there was a metal element. The metal ion species were determined by comparing with the known metal-porphyrin complex standard fluorescence spectrum. If the peaks overlap, the ultraviolet absorption spectrum was used for secondary confirmation. After the preliminary determination of the metal species, the standard solution of the metal was used to draw the fluorescence intensity-concentration standard curve according to the species.

[0147] Quantitative regression calculation: the fluorescence intensity of the unknown sample was corresponded to the standard curve, and the actual metal concentration was calculated by regression.

[0148] Preliminary screening spectrum library: the fluorescence standard peak spectrum database used in the laboratory was established.

[0149] The mass content of each element actually tested is shown in Table 2. The data in Table 2 are the results of volume adjustment to 10 mL. ND in the table means not detected, and the detection limit is 1 ppm.

[0150] Table 2 Determination results of Example 2

[0151]

[0152] From the above table, the mass deviation of metal oxide is 7.7%, which is converted into the content of aluminum element, calcium element and zinc element in the metal oxide, and the content deviation is 5.5%, 7.5% and 8.4% respectively. From the data comparison of example 1 and example 2, it can be seen that: sufficient thermal decomposition conditions of chemical fiber and sufficient ultrasonic treatment conditions are more conducive to obtain more accurate detection results. Otherwise, it is easy to produce other impurities, the characteristic peak produced is doubtful, and the final tracking element content is wrong. Ba belongs to the interference term, which may be due to the influence of other impurities, and actually only contains Al, Ca and Zn. Although the results of this example have certain deviation, the detection results are still better than the existing conventional detection methods.

[0153] Example 3

[0154] Take 32g of polyester fiber as chemical fiber, and it is known that the metal oxide in the chemical fiber contains 0.014g, and the aluminum ion in the metal oxide is 5.44mg, and the vanadium ion is 0.98mg. The metal oxide in the chemical fiber is detected according to the following method steps:

[0155] (1) The specific process conditions for preparing copper oxide loaded activated carbon catalyst are as follows: the mass ratio of copper oxide to activated carbon is 1:10, the volume ratio of hydrogen chloride gas to nitrogen gas is 1:8, and the reaction temperature of hydrogen chloride gas with copper oxide is 200°C (gas source environment temperature is 25°C); the flow rate of HCl gas is 30 mL / min, and the flow rate of N2 is 240 mL / min; the specific operation is as follows: first, replace with nitrogen gas→stable→introduce HCl gas→keep for 30 minutes; use hydrogen fluoride acid grade tail gas absorption device to capture HCl / Cl2, and keep the system at a slight positive pressure.

[0156] Under the condition of 200°C, nitrogen gas is introduced to carry away excess hydrogen chloride gas and hydrogen chloride gas desorbed from the activated carbon; then oxygen and nitrogen gas are continuously introduced to oxidize copper chloride to copper oxide, and the process of oxidizing copper chloride to copper oxide includes low temperature oxidation stage and medium temperature oxidation stage in turn;

[0157] During the low temperature oxidation stage, the gas introduced into the system includes 5% O2, 1% water vapor and 94% N2 in terms of volume percentage, wherein the water vapor is contained in N2, the total flow rate of the gas introduced during the low temperature oxidation stage is 120 mL / min, the temperature is controlled at 220°C, and the duration is 60min;

[0158] The gas introduced into the system during the medium-temperature oxidation stage includes 8% O2 and 92% N2 by volume percentage, the total volume flow rate of the gas introduced during the medium-temperature oxidation stage is 150 mL / min, the flow rate of O2 is 12 mL / min, the flow rate of N2 is 128 mL / min, the temperature is controlled at 270°C, and the duration is 20 min.

[0159] The excess oxygen and chlorine are removed by continuing to introduce nitrogen, and the system is cooled to room temperature 25°C. During the cooling process, pure N2 with a volume ratio of ≥99.99% is introduced at a flow rate of 200 mL / min.

[0160] The activated carbon is washed multiple times with deionized water until the filtrate is free of Cl- (tested by AgNO3); the drying temperature is 105°C, and the drying time is 12 hours or vacuum drying to remove moisture. Finally, 165 g of the catalyst is selected for microwave treatment.

[0161] The microwave treatment conditions are as follows: a fixed sieve is used to screen particles with a suitable particle size range (40 mesh) to ensure uniform heating of the catalyst during microwave treatment and facilitate uniform adhesion to the fiber surface. According to the characteristics of the catalyst, the microwave power is selected to be 600 watts, the treatment time is 12 minutes, and the treatment temperature is controlled at 140°C. The pretreated catalyst is placed in a quartz glass vessel and placed in a microwave reactor. The microwave device is turned on, and the nitrogen environment is maintained. The treatment is carried out according to the set parameters. After the treatment is completed, nitrogen is continuously introduced to allow the catalyst to cool naturally to room temperature in the microwave reactor.

[0162] Finally, 160 g of the catalyst is selected, and the mass ratio of the catalyst to the chemical fiber is 5:1.

[0163] (2) The meta-aramid fiber is mixed with the catalyst in an environment with a volume ratio of oxygen to nitrogen of 25:75, and is completely decomposed at a high temperature of 450°C. The remaining solid material is screened through a 50-mesh sieve. Particles below 50 mesh belong to metal oxides, and the mass is approximately 0.016 g (to be tested metal oxides).

[0164] (3) Preparation of porphyrin solution: three types of tetra(4-carboxyphenyl)porphyrin (TCPP), tetra(4-sulfonatophenyl)porphyrin (H2TSPP), and octaethylporphyrin (OEP) are selected, with a mass ratio of 3:5:2. The solvent is a mixture of water-ethanol-dimethyl sulfoxide (DMSO), with a ratio of water:ethanol:DMSO = 5:3:2 (volume ratio). The concentration of porphyrin in the porphyrin solution is 300 μmol / L.

[0165] Preparation of the salt of the metal oxide to be tested: the metal oxide of step (2) was dissolved in 12 mL of 0.2 mol / L citric acid solution, and first ultrasonic treatment (dissolution stage) was performed for 15 minutes at 200 W and 55°C, and then ultrasonic treatment was performed for 20 minutes at 55°C, and the solution was filtered through a 0.22 μm filter to remove undissolved particles. The clear filtrate obtained was the metal ion solution.

[0166] Three samples, each 2 mL, were taken from the filtrate:

[0167] 1.5 mL of a porphyrin solution (300 μmol / L, TCPP:TSPP:OEP = 3:5:2) was added to each of the above samples;

[0168] Three different pH buffers were added to the three samples, respectively, as follows: 1 mL of 0.1 mol / L formic acid-TEA aqueous solution was added to the first sample to adjust the pH to 2.5; 1 mL of 0.05 mol / L acetic acid-sodium acetate buffer (aqueous solution) was added to the second sample to adjust the pH to 5; and 1 mL of 0.05 mol / L Tris-HCl buffer (aqueous solution) was added to the third sample to adjust the pH to 7.5.

[0169] Volume adjustment: the above three samples were each adjusted to a volume of 10 mL with water, and second ultrasonic treatment (after mixing the fluorescent agent) was performed for 8 minutes at 150 W and a temperature of 25°C, and then ultrasonic treatment was performed for 15 minutes at 50°C, and then the samples were left to stand in the dark for 30 minutes at 25°C, and then the solution was filtered through a 0.22 μm filter to remove undissolved particles, and the clear porphyrin fluorescent agent-metal ion reaction solution obtained was the sample to be tested.

[0170] Fluorescence emission spectrum testing: the results were analyzed, and the fluorescence spectrum of the blank control sample was compared to determine whether there was metal, and the type of metal ion was determined by comparison with the known metal-porphyrin complex standard fluorescence spectrum; if there was peak overlap, UV absorption spectrum was used for secondary confirmation; after initial determination of the type of metal, a standard curve of fluorescence intensity versus concentration was drawn using the standard solution of the metal.

[0171] Quantitative regression calculation: the fluorescence intensity of the unknown sample was matched to the standard curve, and the actual metal concentration was calculated by regression.

[0172] Initial screening spectrum database: a fluorescence standard peak spectrum database used in the laboratory was established.

[0173] The mass content of each element actually tested is shown in Table 3, and the data in Table 3 are the results of 10 mL volume adjustment, wherein ND means not detected, and the detection limit is 1 ppm.

[0174] Table 3 Determination results of Example 3

[0175]

[0176] As can be seen from the above table, the mass deviation of the metal oxide is 14.3%, which is converted into the content deviation of aluminum ions and vanadium ions in the metal oxide, which is 11.6% and 16.8% respectively. Although Ba belongs to an interference term, it may be affected by other impurities, but from the overall data, this method can relatively accurately detect Al and V. In this embodiment, the amount of catalyst is relatively small (5:1 compared to the mass of chemical fiber), which can easily lead to incomplete decomposition and processing of chemical fiber, thereby easily leading to interference terms. If the amount of catalyst is increased (7:1-9:1 compared to the mass of chemical fiber), it is more conducive to precise detection.

[0177] Example 4

[0178] Take 32g of polyamide fiber as chemical fiber, and it is known that the metal oxide in the chemical fiber contains 0.0041g, and the zinc ion in the metal oxide is 2.195mg, and the germanium ion is 0.95mg. The metal oxide in the chemical fiber is detected according to the following method steps:

[0179] (1) The specific process conditions for preparing copper oxide loaded activated carbon catalyst are as follows: the mass ratio of copper oxide to activated carbon is 1:10, the volume ratio of hydrogen chloride gas to nitrogen gas is 1:8, and the reaction temperature of hydrogen chloride gas with copper oxide is 200°C (gas source environment temperature is 25°C); the flow rate of HCl gas is 30 mL / min, and the flow rate of N2 is 240 mL / min; The specific operation is as follows: first replace with nitrogen gas→stable→introduce HCl gas→keep for 30 minutes; use a hydrofluoric acid grade tail gas absorption device to capture HCl / Cl2, and maintain a slight positive pressure in the system.

[0180] Under the condition of 200°C, nitrogen gas is introduced to carry away excess hydrogen chloride gas and hydrogen chloride gas desorbed from the activated carbon; then oxygen and nitrogen gas are continuously introduced to oxidize copper chloride to copper oxide, and the process of oxidizing copper chloride to copper oxide includes low temperature oxidation stage and medium temperature oxidation stage in turn;

[0181] During the low temperature oxidation stage, the gas introduced into the system includes 5% O2, 1% water vapor and 94% N2 in terms of volume percentage, wherein the water vapor is contained in N2, the total flow rate of the gas introduced during the low temperature oxidation stage is 120 mL / min, the temperature is controlled at 220°C, and the duration is 60min;

[0182] The gas introduced into the system during the medium-temperature oxidation stage includes 7.5% of O2 and 92.5% of N2 in terms of volume percentage, the total volume flow rate of the gas introduced during the medium-temperature oxidation stage is 150 mL / min, the flow rate of O2 is 12 mL / min, the flow rate of N2 is 128 mL / min, the temperature is controlled at 270°C, and the duration is 20 min.

[0183] The excess oxygen and chlorine are removed by continuing to introduce nitrogen, and the system is cooled to room temperature 25°C. During the cooling process, pure N2 with a volume ratio of ≥99.99% is introduced at a flow rate of 200 mL / min.

[0184] The activated carbon is washed multiple times with deionized water until the filtrate is free of Cl⁻ (tested by AgNO3); the drying temperature is 105°C, and the drying time is 12 hours or vacuum drying to remove moisture. Finally, 230 g of the catalyst is selected for microwave treatment.

[0185] The microwave treatment conditions are as follows: a fixed sieve is used to screen particles with a suitable particle size range (30 mesh) to ensure uniform heating of the catalyst during microwave treatment and facilitate uniform adhesion to the fiber surface. According to the characteristics of the catalyst, the microwave power is selected to be 500 watts, the treatment time is 5 minutes, and the treatment temperature is controlled at 120°C. The pretreated catalyst is placed in a quartz glass container and placed in a microwave reactor. The microwave device is turned on, and the nitrogen environment is maintained. The treatment is carried out according to the set parameters. After the treatment is completed, nitrogen is continuously introduced to allow the catalyst to cool naturally to room temperature in the microwave reactor.

[0186] Finally, 224 g of the catalyst is selected, and the mass ratio of the catalyst to the chemical fiber is 7:1.

[0187] (2) The meta-aramid fiber is mixed with the catalyst in an environment with a volume ratio of oxygen to nitrogen of 25:75, and is completely decomposed at a high temperature of 450°C. The remaining solid material is screened through a 50-mesh sieve. The particles below 50 mesh are metal oxides, and the mass of the metal oxides is approximately 0.00458 g (to be measured).

[0188] (3) Preparation of porphyrin solution: three types of tetra(4-carboxyphenyl)porphyrin (TCPP), tetra(4-sulfonatophenyl)porphyrin (H2TSPP), and octaethylporphyrin (OEP) are selected, with a mass ratio of 3:5:2. The solvent is a mixture of water-ethanol-dimethyl sulfoxide (DMSO), with a volume ratio of water:ethanol:DMSO = 5:3:2. The concentration of porphyrin in the porphyrin solution is 300 μmol / L.

[0189] Preparation of the salt of the metal oxide to be tested: the metal oxide of step (2) was dissolved in 12 mL of 0.2 mol / L citric acid solution, and first ultrasonic treatment (dissolution stage) was performed for 15 minutes at 200 W and 55°C, followed by ultrasonic treatment for 20 minutes at 55°C, 0.22 μm membrane filtration was performed to remove undissolved particles, and a clear filtrate was obtained, which was the metal ion solution.

[0190] Three samples, each 2 mL, were taken from the filtrate:

[0191] 1.5 mL of the porphyrin solution (300 μmol / L, TCPP:TSPP:OEP = 3:5:2) was added to each of the above samples.

[0192] Three different pH buffers were added to the three samples respectively, and the specific operation was as follows: 1 mL of 0.1 mol / L formic acid-TEA aqueous solution was added to the first sample to adjust the pH to 2.5; 1 mL of 0.05 mol / L acetic acid-sodium acetate buffer (aqueous solution) was added to the second sample to adjust the pH to 5; and 1 mL of 0.05 mol / L Tris-HCl buffer (aqueous solution) was added to the third sample to adjust the pH to 7.5.

[0193] Volume setting reaction: the above three samples were each diluted to 10 mL with water, and second ultrasonic treatment (after mixing the fluorescence agent) was performed for 8 minutes at 150 W and a temperature of 25°C, followed by ultrasonic treatment for 15 minutes at 50°C, then the samples were kept in the dark for 30 minutes at 25°C, 0.22 μm membrane filtration was performed to remove undissolved particles, and a clear porphyrin fluorescence agent-metal ion reaction solution was obtained, which was the sample to be tested.

[0194] Test the fluorescence emission spectrum: analyze the results, compare the fluorescence spectrum with the blank control sample, determine whether there is a metal element, compare with the known metal-porphyrin complex standard fluorescence spectrum to determine the type of metal ion; if there is peak overlap, use ultraviolet absorption spectrum for secondary confirmation; after preliminary determination of the type of metal, draw the fluorescence intensity-concentration standard curve using the standard solution of the metal according to its type.

[0195] Quantitative regression calculation: the fluorescence intensity of the unknown sample was matched to the standard curve, and the actual metal concentration was calculated by regression.

[0196] Preliminary screening spectrum library: a fluorescence standard peak database used in the laboratory was established.

[0197] The mass content of each element actually tested is shown in Table 4, and the data in Table 4 is the result of dilution to 10 mL, wherein ND means not detected, and the detection limit is 1 ppm.

[0198] Table 4 Determination results of Example 4

[0199]

[0200] As can be seen from the above table, the mass deviation of the metal oxide is 11.6%, which is converted into the content deviation of zinc element and germanium element in the metal oxide, which is 9.1% and 12.4% respectively. Cu, although it belongs to the interference term, may be affected by other impurities, but from the overall data, this method can relatively accurately detect the corresponding metal oxide. The catalyst particle size (30 mesh) of this embodiment is relatively high, and more accurate detection results can be obtained if a relatively small particle size (such as 40 mesh) catalyst is used. Because the catalyst mesh number is larger, the contact area is small, the microwave treatment conditions are not suitable, the catalyst is not fully excited, and the content of the metal oxide is relatively small, so the risk of deviation is higher.

[0201] Comparative Example 1

[0202] The same method as in Example 1 was used to detect the metal oxide, except that no catalyst was used in this comparative example 1, as follows:

[0203] 32g of meta-aramid fiber was taken as the chemical fiber, and it was known that the metal oxide in the chemical fiber contained 0.0196g, among which the aluminum ion was 6.22mg, the calcium ion was 2.80mg, and the zinc ion was 3.15mg. The metal oxide in the chemical fiber was detected according to the following method steps:

[0204] (1) The meta-aramid fiber was mixed with the catalyst in an environment with a volume ratio of oxygen to nitrogen of 25:75, and was completely decomposed at 500°C. The remaining solid material was sieved through a 50 mesh sieve, and the particles below 50 mesh were metal oxides, about 0.0262g (to be detected metal oxide).

[0205] (2) Preparation of porphyrin solution: three kinds of tetra(4-carboxyphenyl) porphyrin (TCPP), tetra(4-sulfonic acid phenyl) porphyrin (H2TSPP), and octaethyl porphyrin (OEP) were selected, with a mass ratio of 3:5:2. The solvent was a mixture of water-ethanol-dimethyl sulfoxide (DMSO), with a ratio of water:ethanol:DMSO = 5:3:2 (volume ratio). The concentration of porphyrin in the porphyrin solution was 300μmol / L.

[0206] Preparation of the salt of the metal oxide to be tested: the metal oxide of step (2) was dissolved in 12 mL of 0.2 mol / L citric acid solution, first ultrasonic treatment (dissolution stage): 15 minutes, 200 W, 55°C, then ultrasonic treatment at 55°C for 20 minutes, 0.22 μm filter membrane filtration to remove undissolved particles. The clear filtrate obtained was the metal ion solution.

[0207] Three samples were taken from the filtrate, each 2 mL:

[0208] 1.5 mL of porphyrin solution (300 μmol / L, TCPP:TSPP:OEP = 3:5:2) was added to each of the above samples.

[0209] Three different pH buffers were added to the three samples respectively, the specific operation being: 1 mL of 0.1 mol / L formic acid-TEA aqueous solution was added to the first sample to adjust the pH to 2.5; 1 mL of 0.05 mol / L acetic acid-sodium acetate buffer (aqueous solution) was added to the second sample to adjust the pH to 5; 1 mL of 0.05 mol / L Tris-HCl buffer (aqueous solution) was added to the third sample to adjust the pH to 7.5.

[0210] Reaction volume setting: the above three samples were each diluted to 10 mL with water, second ultrasonic treatment (after mixing the fluorescence agent): the time was shortened to 8 minutes, 150 W, the temperature was controlled at 25°C, then ultrasonic treatment at 50°C for 15 minutes, then the samples were kept in the dark for 30 minutes at 25°C, 0.22 μm filter membrane filtration was performed to remove undissolved particles, and the clear porphyrin fluorescence agent-metal ion reaction solution obtained was the sample to be tested.

[0211] Test the fluorescence emission spectrum: analyze the results, compare the fluorescence spectrum with the blank control sample, determine whether there is metal element, compare with the known metal-porphyrin complex standard fluorescence spectrum to determine the type of metal ion; if there is peak overlap, take the following measures: ultraviolet absorption spectrum secondary confirmation; after preliminary determination of the type of metal, draw the fluorescence intensity-concentration standard curve using the standard solution of the metal according to its type.

[0212] Quantitative regression calculation: the fluorescence intensity of the unknown sample was corresponded to the standard curve, and the actual metal concentration was calculated by regression.

[0213] Preliminary screening spectrum library: a fluorescence standard peak database used in the laboratory was established.

[0214] The mass content of each element actually tested is shown in Table 5, and the data in Table 5 is the result of dilution to 10 mL, wherein ND means not detected, and the detection limit is 1 ppm.

[0215] Table 5 Determination results of Comparative Example 1

[0216]

[0217] From the comparison of the results of Comparative Example 1 and Example 1, it can be seen that if no catalyst is added, the meta-aramid fiber is not fully thermally decomposed, resulting in the presence of other impurities, the characteristic peaks produced are questionable, and the final trace element content is incorrect. It is found that Ba is an interference term, and it is possible that other impurities are present, and only Al, Ca, and Zn are actually present. From the above data, it can be seen that the mass deviation of the metal oxides detected in Comparative Example 1 is 33.7%, and the above conversion into the content of the metal oxides at the beginning, the content deviation of aluminum element, calcium element, and zinc element is 36.2%, 30.0%, and 31.6%, respectively, and it is found that Ba is an interference term.

[0218] Comparative Example 2

[0219] The same method as in Example 1 was used to detect metal oxides, except that in Comparative Example 2, the catalyst was prepared without microwave treatment, as follows:

[0220] 32 g of meta-aramid fiber was taken as the chemical fiber, and it was known that the metal oxides in the chemical fiber contained a total of 0.0196 g, and among the metal oxides, the aluminum ion was 6.22 mg, the calcium ion was 2.80 mg, and the zinc ion was 3.15 mg. The metal oxides in the chemical fiber were detected according to the following method steps:

[0221] (1) The specific process conditions for preparing the copper oxide-loaded activated carbon catalyst were as follows: the mass ratio of copper oxide to activated carbon was 1:10, the volume ratio of hydrogen chloride gas to nitrogen gas was 1:8, and the reaction temperature of hydrogen chloride gas with copper oxide was 200°C (the gas source environment temperature was 25°C); the flow rate of HCl gas was 30 mL / min, and the flow rate of N2 was 240 mL / min; the specific operation was as follows: first, replace with nitrogen gas → stabilize → introduce HCl gas → maintain for 30 minutes; use a hydrofluoric acid grade tail gas absorption device to capture HCl / Cl2, and maintain a slight positive pressure in the system.

[0222] At 200°C, nitrogen gas was introduced to carry away excess hydrogen chloride gas and hydrogen chloride gas desorbed from the activated carbon; then oxygen and nitrogen were continuously introduced to oxidize copper chloride to copper oxide, and the process of oxidizing copper chloride to copper oxide included a low-temperature oxidation stage and a medium-temperature oxidation stage in sequence;

[0223] The low-temperature oxidation stage process, according to the volume percentage, the gas into the system includes 5% of O2, 1% of water vapor and 94% of N2, wherein the water vapor is contained in N2, the total flow of the low-temperature oxidation stage gas is 120 mL / min, the temperature is controlled at 220℃, and the duration is 60 min;

[0224] The medium-temperature oxidation stage process, according to the volume percentage, the gas into the system includes 7.5% of O2 and 92.5% of N2, the total volume flow of the medium-temperature oxidation stage gas is 150 mL / min, the flow rate of O2 is 12 mL / min, the flow rate of N2 is 128 mL / min, the temperature is controlled at 270℃, and the duration is 20 min.

[0225] Continue to introduce nitrogen to carry away excess oxygen and chlorine, and cool the system to room temperature 25℃, in the process of cooling to room temperature, pure N2 with volume ratio ≥99.99% is introduced, and the flow rate is 200 mL / min.

[0226] Wash the activated carbon with deionized water several times until the filtrate is free of Cl⁻ reaction (AgNO3 test); dry at 105℃ for 12 hours or vacuum dry to remove moisture.

[0227] Finally, select 256g of catalyst, and the mass ratio of chemical fiber to catalyst is 8:1.

[0228] (2) Mix the meta-aramid fiber with the catalyst in an oxygen and nitrogen volume ratio of 25:75, and completely decompose at 500℃, screen the remaining solid material through a 50 mesh sieve, and the particles below 50 mesh are metal oxides, about 0.0240g (to be tested metal oxide).

[0229] (3) Prepare a porphyrin solution: select four (4-carboxyphenyl) porphyrin (TCPP), four (4-sulfonic acid phenyl) porphyrin (H2TSPP), and octaethyl porphyrin (OEP) with a mass ratio of 3:5:2, and the solvent is a mixture of water-ethanol-dimethyl sulfoxide (DMSO) with a volume ratio of water:ethanol:DMSO = 5:3:2; and the concentration of porphyrin in the porphyrin solution is 300 μmol / L.

[0230] Prepare the salt of the metal oxide to be tested: dissolve the metal oxide of step (2) with 12 mL of 0.2 mol / L citric acid solution, ultrasonic (dissolution stage) for the first time: 15 minutes, 200W, 55℃, then ultrasonic treatment at 55℃ for 20 minutes, 0.22 μm filter membrane filtration to remove undissolved particles. The clear filtrate is the metal ion solution.

[0231] Three 2 mL samples were taken from the filtrate:

[0232] 1.5 mL of porphyrin solution (300 μmol / L, TCPP:TSPP:OEP = 3:5:2) was added to each sample.

[0233] Three different pH buffers were added to the three samples respectively. 1 mL of 0.1 mol / L formic acid-TEA aqueous solution was added to the first sample to adjust the pH to 2.5; 1 mL of 0.05 mol / L acetic acid-sodium acetate buffer (aqueous solution) was added to the second sample to adjust the pH to 5; and 1 mL of 0.05 mol / L Tris-HCl buffer (aqueous solution) was added to the third sample to adjust the pH to 7.5.

[0234] Volume adjustment: the above three samples were each adjusted to 10 mL with water. The second ultrasonic treatment (after mixing the fluorescent agent): the time was shortened to 8 minutes, 150 W, and the temperature was controlled at 25°C. Then the samples were ultrasonically treated at 50°C for 15 minutes, and then kept in the dark for 30 minutes at 25°C. The samples were then filtered through a 0.22 μm filter to remove the undissolved particles, to obtain a clear porphyrin fluorescent agent-metal ion reaction solution, which was the sample to be tested.

[0235] Fluorescence emission spectrum test: the results were analyzed, and the fluorescence spectrum of the blank control sample was compared to determine whether there was a metal element. The metal ion type was determined by comparing with the known metal-porphyrin complex standard fluorescence spectrum. If the peaks overlap, the ultraviolet absorption spectrum was used for secondary confirmation. After the preliminary determination of the metal type, the standard solution of the metal was used to draw the fluorescence intensity-concentration standard curve according to the type of the metal.

[0236] Quantitative regression calculation: the fluorescence intensity of the unknown sample was corresponded to the standard curve, and the actual metal concentration was calculated by regression.

[0237] Preliminary screening spectrum library: a fluorescence standard peak spectrum database used in the laboratory was established.

[0238] The mass content of each element actually tested is shown in Table 6. The data in Table 6 is the result of adjusting the volume to 10 mL. ND means not detected, and the detection limit is 1 ppm.

[0239] Table 6 Determination results of Comparative Example 2

[0240]

[0241] From the comparison of the results of Comparative Example 2 and Example 1, it can be seen that if the catalyst preparation process is not subjected to microwave treatment, the meta-aramid fiber is not fully thermally decomposed, resulting in the presence of other impurities, the characteristic peaks generated are questionable, and the final trace element content is incorrect. It is found that Ba is an interference term, which may be due to the influence of other impurities, and actually only contains Al, Ca and Zn. From the above data, it can be seen that the mass deviation of the metal oxides detected in Comparative Example 2 is 22.4%, which is converted into the content of the metal oxides at the beginning, the content deviation of aluminum element, calcium element and zinc element is 20.6%, 21.0% and 25.3% respectively, and it is found that Ba is an interference term.

[0242] Comparative Example 3

[0243] The same method as in Example 1 was used to detect metal oxides, except that in Comparative Example 3, the acid dissolution method was used to determine the chemical fibers, as follows:

[0244] 32 g of meta-aramid fiber was taken as the chemical fiber, and it was known that the chemical fiber contained a total of 0.0196 g of metal oxides. Among the metal oxides, the aluminum ion was 6.22 mg, the calcium ion was 2.80 mg, and the zinc ion was 3.15 mg. The metal oxides in the chemical fiber were detected according to the following method steps:

[0245] 1. Sample pretreatment and premixing:

[0246] Sample weighing: 0.1-0.3 g of meta-aramid fiber cut to a length of 1 mm or less was taken and placed in a PTFE digestion tube.

[0247] Sulfuric acid addition: 8-10 mL of 75% sulfuric acid aqueous solution (mass concentration) was added to ensure that the fiber was completely immersed, and the solution was gently shaken to ensure full contact with the sample.

[0248] Premixing and standing: stand at room temperature for 20 minutes to allow the sulfuric acid to initially soak the fiber and avoid violent boiling at the beginning of digestion.

[0249] Microwave digestion temperature rising stage: first stage: from room temperature to 120°C in 5 minutes, keep for 5 minutes (initially soften the fiber); second stage: from 120°C to 180°C in 5 minutes, keep for 10 minutes (promote amide bond hydrolysis); third stage: from 180°C to 230°C in 5 minutes, keep for 30 minutes (core digestion stage, destroy benzene ring structure);

[0250] Pressure control: maximum pressure ≤1.2 MPa (to avoid leakage of the digestion tube).

[0251] Digestion end point: the solution is light brown or light yellow, and there are no obvious solid particles.

[0252] After digestion is completed, move the digestion tube to a fume hood and cool to room temperature (about 40 minutes to avoid cracking the container due to sudden cooling).

[0253] Transfer and dilution: transfer all solutions to a 50 mL PTFE volumetric flask; add ultrapure water to 1 cm below the calibration line, stand for 10 minutes (to release bubbles), then add ultrapure water dropwise to the calibration line, tightly cap and shake for 5 times, and obtain the test mother liquor.

[0254] 2. ICP-MS detection pretreatment:

[0255] Dilution: take 10 mL of the test mother liquor, dilute to 100 mL with ultrapure water (10-fold dilution), so that the concentration of sulfuric acid is reduced to below 7%-8%.

[0256] Blank experiment: take 8-10 mL of a 75% sulfuric acid aqueous solution, and perform the above digestion and dilution steps synchronously as a blank control (to deduct matrix interference).

[0257] Then use ICP-MS for detection. The actual test data are shown in Table 7, where the data in Table 7 are the results of dilution to 10 mL, and ND means not detected, and the detection limit is 1 ppm.

[0258] Table 7 Determination results of Comparative Example 3

[0259]

[0260] As can be seen from the above table, the meta-aramid fiber contains trace elements of aluminum, calcium and zinc. As can be seen from the above data, the above is converted into the content of the metal oxide at the beginning, and the content deviation of aluminum, calcium and zinc is 14.7%, 15.8% and 16.8%, respectively. Due to the complexity of the fiber digestion process, reagent pollution in the pretreatment, and interference of ions with the same mass number, the results deviate. The accuracy of the determination method is obviously lower than that of the detection method described in the present application.

[0261] Comparative Example 4

[0262] The same method as in Example 1 is used to detect the metal oxide, except that in Comparative Example 4, the catalyst used is copper oxide and activated carbon, i.e., directly mixing copper oxide and activated carbon with chemical fibers for high-temperature decomposition, wherein the mass ratio of copper oxide and activated carbon is the same as that used in the preparation of the activated carbon catalyst loaded with copper oxide in Example 1, and the total mass of copper oxide and activated carbon is the same as the amount of catalyst used in Example 1. The chemical fibers used in Comparative Example 4 are the same as those in Example 1.

[0263] Take 32 g of meta-aramid fiber as chemical fiber, and it is known that the metal oxide in the chemical fiber contains 0.0196 g, among which the aluminum ion is 6.22 mg, the calcium ion is 2.80 mg, and the zinc ion is 3.15 mg. The metal oxide in the chemical fiber is detected according to the following method steps:

[0264] (1) The mass ratio of copper oxide and activated carbon as catalyst is 1:10, and finally 256 g of catalyst is selected, with a mass ratio of 8:1 to the chemical fiber.

[0265] (2) The meta-aramid fiber is mixed with the catalyst in an environment with a volume ratio of oxygen to nitrogen of 25:75, and is completely decomposed at 500°C. The remaining solid material is sieved through a 50 mesh sieve, and the particles below 50 mesh are metal oxides, about 0.0243 g (metal oxide to be tested).

[0266] (3) Preparation of porphyrin solution: select four (4-carboxyphenyl) porphyrin (TCPP), tetra (4-sulfonic acid phenyl) porphyrin (H2TSPP), and octaethyl porphyrin (OEP) with a mass ratio of 3:5:2, and the solvent is a mixture of water-ethanol-dimethyl sulfoxide (DMSO) with a volume ratio of water:ethanol:DMSO = 5:3:2; and the concentration of porphyrin in the porphyrin solution is 300 μmol / L.

[0267] Preparation of metal oxide salt to be tested: the metal oxide in step (2) is dissolved with 12 mL of 0.2 mol / L citric acid solution, ultrasonic treatment (dissolution stage) for the first time: 15 minutes, 200 W, 55°C, and then ultrasonic treatment at 55°C for 20 minutes, 0.22 μm filter membrane filtration to remove undissolved particles. The clear filtrate obtained is the metal ion solution.

[0268] Take 3 samples from the above filtrate, each 2 mL:

[0269] Add 1.5 mL of porphyrin solution (300 μmol / L, TCPP:TSPP:OEP = 3:5:2) to each of the above samples

[0270] Add three different pH buffers to the three samples respectively, the specific operation is: add 1 mL of 0.1 mol / L formic acid-TEA aqueous solution to the first sample to adjust the pH to 2.5; add 1 mL of 0.05 mol / L acetic acid-sodium acetate buffer (aqueous solution) to the second sample to adjust the pH to 5; add 1 mL of 0.05 mol / L Tris-HCl buffer (aqueous solution) to the third sample to adjust the pH to 7.5.

[0271] Volume reaction: the above three samples are added with water to 10 mL, the second ultrasonic (after mixing the fluorescent agent): the time is shortened to 8 minutes, 150W, the temperature is controlled at 25℃, then ultrasonic treatment is carried out at 50℃ for 15 minutes, then it is placed in dark for 30 minutes, maintains 25℃, 0.22 μm filter membrane filtration is carried out, the unsolved particles are removed, the clear porphyrin fluorescent agent-metal ion reaction liquid is obtained, that is, the sample to be measured.

[0272] Test fluorescence emission spectrum: the result analysis is carried out, the fluorescence spectrum of the blank control sample is compared, the metal element is judged, the known metal-porphyrin complex standard fluorescence spectrum is compared, the metal ion type is judged; if the peak overlaps, the ultraviolet absorption spectrum is used for secondary confirmation; after the metal type is initially judged, the standard solution of the metal is used to draw the fluorescence intensity-concentration standard curve according to the type.

[0273] Quantitative regression calculation: the fluorescence intensity of the unknown sample is corresponded to the standard curve, and the actual metal concentration is calculated by regression.

[0274] Preliminary screening spectrum library: the fluorescence standard peak database used in the laboratory is established.

[0275] The mass content of each element actually tested is as shown in Table 8, and the data in Table 8 is the result of 10 mL volume.

[0276] Table 8 Determination results of Comparative Example 4

[0277]

[0278] As can be seen from the above table, the mass deviation of the metal oxide is 24.0%, which is converted into the content of aluminum element, calcium element and zinc element in the metal oxide, and the content deviations are 25.7%, 21.4% and 22.7% respectively. It is found that Ba belongs to the interference term, and the actual content only contains Al, Ca and Zn due to the influence of other impurities. In the comparative experiment, it is found that if the method of directly mixing copper oxide powder and activated carbon to prepare the catalyst in the prior art is used, the structure of the prepared catalyst is loose, the loading efficiency is low, and the catalytic effect is obviously inferior to the method described in the present application. The main reason is that the CuO particles are easy to accumulate on the surface of the activated carbon, causing partial pore blockage, thereby significantly reducing the specific surface area of the activated carbon and the effective utilization rate of the pore structure, limiting the play of the adsorption-catalysis synergistic effect, and further affecting the final reaction efficiency and the accuracy of the test results.

[0279] Compared with the prior art, the application realizes uniform adsorption of copper chloride on the surface and pore structure of activated carbon by in-situ conversion of CuO into CuCl2 solution and then using the acid and solubility characteristics of CuCl2 solution. After heat treatment, CuCl2 is in-situ converted into CuO on the carrier. The method not only makes the distribution of copper oxide more uniform, but also generates CuO particles with smaller particle size and higher dispersity, which can have stronger ion exchange and coordination with oxygen-containing functional groups on the surface of activated carbon, thereby enhancing the binding strength between copper species and the carrier, and improving the structural stability and thermal stability of the catalyst.

[0280] If CuO and activated carbon are used separately, the synergistic effect between them cannot be realized, and the catalytic process efficiency can be low due to the broken reaction path. In the actual reaction process, the target component in the chemical fiber needs to be catalytically cracked on the surface of CuO first, and then the cracking products are adsorbed and fixed by activated carbon. However, such a sequence-dependent path has problems such as long diffusion path of reactants, low conversion rate, easy generation of by-products, and even the occurrence of reverse reaction or cross-reaction due to improper reaction sequence, which further affects the reaction efficiency and product purity.

[0281] In addition, CuO can absorb moisture in humid air, resulting in a decrease in catalytic activity. The use of activated carbon alone can also reduce efficiency due to saturation of adsorption sites, and frequent regeneration is required, resulting in an increase in operating costs. In the supported catalyst prepared by the application, the high dispersion state of CuO significantly improves the catalytic reaction rate and conversion rate, effectively delays the saturation of activated carbon adsorption, reduces the regeneration frequency, and prolongs the overall service life of the catalyst.

[0282] In summary, the application reasonably designs the conversion path of copper oxide precursor and the loading method of activated carbon, takes into account the reaction activity and carrier structure stability, and fully utilizes the synergistic effect of the supported catalyst. The application has obvious technical progress and industrial application prospect in handling low-concentration impurity substances and showing significant advantages in catalytic efficiency and analysis accuracy.

[0283] Comparative Example 5

[0284] The same method as in Example 1 was used to detect metal oxides, and the chemical fiber used in Comparative Example 5 was the same as in Example 1. The difference is that in step (1) of Comparative Example 5, copper chloride aqueous solution was directly used to mix and adsorb with activated carbon (the amount of copper chloride used was the same as the molar amount of copper oxide in Example 1, and the amount of activated carbon used was the same as in Example 1).

[0285] Take 32 g meta-aramid fiber as chemical fiber, it is known that the metal oxide in the chemical fiber contains 0.0196 g, among which the aluminum ion is 6.22 mg, the calcium ion is 2.80 mg, and the zinc ion is 3.15 mg. The metal oxide in the chemical fiber is detected according to the following method steps:

[0286] (1) Put the activated carbon into the copper chloride solution, and continue to introduce oxygen and nitrogen to oxidize the copper chloride to copper oxide. The process of oxidizing copper chloride to copper oxide includes low-temperature oxidation stage and medium-temperature oxidation stage in turn;

[0287] During the low-temperature oxidation stage, the gas introduced into the system includes 5% O2, 1% water vapor and 94% N2 in terms of volume percentage, wherein the water vapor is contained in N2. The total flow rate of the gas introduced during the low-temperature oxidation stage is 120 mL / min, the temperature is controlled at 220℃, and the duration is 60 min;

[0288] During the medium-temperature oxidation stage, the gas introduced into the system includes 8% O2 and 92% N2 in terms of volume percentage. The total volume flow rate of the gas introduced during the medium-temperature oxidation stage is 150 mL / min, the flow rate of O2 is 12 mL / min, the flow rate of N2 is 128 mL / min, the temperature is controlled at 270℃, and the duration is 20 min.

[0289] Continue to introduce nitrogen to carry away excess oxygen and chlorine, and cool the system to room temperature 25℃. During the cooling process to room temperature, pure N2 with a volume ratio of ≥99.99% is introduced, and the flow rate is 200 mL / min.

[0290] Wash the activated carbon with deionized water several times until the filtrate is free of Cl⁻ reaction (AgNO3 test); dry at 105℃ for 12 hours or vacuum dry to remove moisture. Finally, select 260 g of catalyst for microwave treatment.

[0291] The conditions for microwave treatment are: use a fixed sieve to screen particles with a suitable particle size range (40 mesh) to ensure uniform heating of the catalyst during microwave treatment, which is more conducive to uniform adhesion to the fiber surface. According to the characteristics of the catalyst, select microwave power of 600 watts, treatment time of 12 minutes, and treatment temperature controlled at 140℃. Put the pretreated catalyst into a quartz glass container and place it in a microwave reactor. Turn on the microwave device and maintain a nitrogen environment. Process according to the set parameters. After the treatment is completed, continue to introduce nitrogen to allow the catalyst to cool naturally to room temperature in the microwave reactor.

[0292] Finally, select 256 g of catalyst, with a mass ratio of chemical fiber to catalyst of 8:1.

[0293] (2) The meta-aramid fiber is mixed with a catalyst in an environment with a volume ratio of oxygen to nitrogen of 25:75, and is completely decomposed at 500°C. The remaining solid material is sieved through a 50-mesh sieve. Particles smaller than 50 mesh are metal oxides, and are approximately 0.0236 g (to be tested metal oxides).

[0294] (3) Preparation of porphyrin solution: three types of porphyrin, namely, tetrakis(4-carboxyphenyl)porphyrin (TCPP), tetrakis(4-sulfonatophenyl)porphyrin (H2TSPP), and octaethylporphyrin (OEP), are selected, with a mass ratio of 3:5:2. The solvent is a mixture of water, ethanol, and dimethyl sulfoxide (DMSO), with a volume ratio of water:ethanol:DMSO = 5:3:2. The concentration of porphyrin in the porphyrin solution is 300 μmol / L.

[0295] Preparation of salt of to-be-tested metal oxide: the metal oxide in step (2) is dissolved in 12 mL of 0.2 mol / L citric acid solution. First ultrasonic treatment (dissolution stage): 15 minutes, 200 W, 55°C. Then ultrasonic treatment at 55°C for 20 minutes. Filtration through a 0.22 μm filter to remove undissolved particles. A clear filtrate is obtained, which is a metal ion solution.

[0296] Three samples, each 2 mL, are taken from the above filtrate.

[0297] In each of the above samples, 1.5 mL of porphyrin solution (300 μmol / L, TCPP:TSPP:OEP = 3:5:2) is added.

[0298] Three different pH buffers are added to the three samples, respectively. Specifically, 1 mL of 0.1 mol / L formic acid-TEA aqueous solution is added to the first sample to adjust the pH to 2.5. 1 mL of 0.05 mol / L acetic acid-sodium acetate buffer (aqueous solution) is added to the second sample to adjust the pH to 5. 1 mL of 0.05 mol / L Tris-HCl buffer (aqueous solution) is added to the third sample to adjust the pH to 7.5.

[0299] Volume setting reaction: the above three samples are each diluted to 10 mL with water. Second ultrasonic treatment (after mixing the fluorescence agent): the time is shortened to 8 minutes, 150 W, and the temperature is controlled at 25°C. Then ultrasonic treatment at 50°C for 15 minutes. Then avoid light for 30 minutes, keep 25°C. Filtration through a 0.22 μm filter to remove undissolved particles. A clear porphyrin fluorescence agent-metal ion reaction solution is obtained, which is the to-be-tested sample.

[0300] Test fluorescence emission spectrum: analyze the results, compare the fluorescence spectrum of the blank control sample, determine whether there is a metal element, compare with the known metal-porphyrin complex standard fluorescence spectrum, determine the type of metal ion; if the peaks overlap, take the UV absorption spectrum for secondary confirmation; after the initial determination of the type of metal, use the standard solution of the metal to draw the fluorescence intensity-concentration standard curve according to the type.

[0301] Quantitative regression calculation: the fluorescence intensity in the unknown sample is corresponded to the standard curve, and the actual metal concentration is calculated by regression.

[0302] Preliminary screening spectrum library: establish the fluorescence standard peak graph database used in the laboratory.

[0303] The specific detection results are as follows in Table 9. The data in Table 9 are the results of 10 mL of constant volume. ND is not detected, and the detection limit is 1 ppm.

[0304] Table 9 Determination results of Comparative Example 5

[0305]

[0306] As can be seen from the above table, the mass deviation of the metal oxide is 20.4%, which is converted into the content of aluminum element, calcium element and zinc element in the metal oxide, and the content deviation is 19.2%, 20.8% and 21.5% respectively. It is found that Ba belongs to the interference term, which may be due to the influence of other impurities, and only Al, Ca and Zn are actually contained. The detection result is obviously lower than the detection method of Example 1. In Comparative Example 5, copper chloride is dissolved in water and then activated carbon is added for adsorption, which has certain defects and can cause impurities in the detection system. The preparation method of the catalyst described in the application has obvious advantages, which avoids the multiple problems caused by directly using copper chloride. In the traditional method, if copper chloride is directly weighed and adsorbed on activated carbon, although the mass can be accurately controlled on the surface, on the one hand, there is a lack of sufficient interaction between copper chloride and activated carbon, mainly physical adsorption, which leads to uneven distribution of copper chloride in activated carbon and easy formation of local enrichment or agglomeration; on the other hand, due to the thermal stability and volatility of copper chloride, it is easy to migrate, desorb or decompose during high temperature treatment, causing copper species loss or forming non-uniform catalytic active sites, thereby significantly reducing the catalytic efficiency.

[0307] More importantly, the addition of copper chloride alone cannot guarantee that it can be finally converted into the required proportion of copper oxide. Even if the appropriate amount of CuCl2 is weighed in theory, the oxidation reaction process is limited by the local reaction environment, diffusion efficiency and oxygen supply conditions, which is easy to produce residual CuCl2 that is not completely oxidized, thereby causing the residual of chloride ions. These unreacted copper chlorides may release Cl element impurities in the subsequent high-temperature pyrolysis of chemical fibers, interfere with the analysis and detection results, and damage the long-term stability of the catalyst.

[0308] In contrast, the present application adopts an in-situ reaction method, using copper oxide (CuO) and activated carbon as precursors, and introducing appropriate hydrogen chloride gas (HCl) to react under controllable conditions to obtain CuCl2, which has the following advantages:

[0309] Copper oxide is mixed with activated carbon in advance, and CuO forms a certain degree of interface binding with the surface of activated carbon through van der Waals force, surface polarity, etc., providing site constraints for the subsequent generation of copper chloride;

[0310] During the HCl introduction process, water is released controllably, and the generated CuCl2 is in a very short-range migration state, which can be immediately adsorbed, exchanged or solidified in the pores and surface of activated carbon to form highly dispersed copper species;

[0311] The porous structure (micropores, mesopores) of activated carbon enables Cu²⁺ to be further stabilized on the carbon carrier through ion exchange, pore adsorption, and weak coordination mechanisms, significantly enhancing its binding force and inhibiting late-stage sintering or agglomeration;

[0312] Hydrogen chloride is a volatile gas, and excess HCl and reaction byproducts can be removed by nitrogen after the reaction without introducing additional impurities;

[0313] Compared with direct dry adsorption on the surface, the in-situ reaction generated copper chloride is "self-positioned" on the pore surface of activated carbon through liquid phase intermediate state or molecular scale, thus achieving uniform distribution and not blocking the pores, and maximizing the adsorption performance of activated carbon.

[0314] In the preparation method of the catalyst described in the present application, the adsorbed CuCl2 is further converted into stable CuO under high temperature conditions. This process can achieve redox balance through high-temperature air calcination, anchoring the copper species firmly on the activated carbon carrier, and constructing a catalytic center with good structural dispersion and interface activity, significantly improving the reaction efficiency and impurity resistance of the catalyst in the process of fiber decomposition.

[0315] In addition, the hydrogen chloride introduction process has good controllability, and the concentration, introduction time and temperature can be finely adjusted to precisely control the copper loading and dispersion state, meeting the requirements of different fiber treatment and detection applications. At the same time, hydrogen chloride and reaction gases can be recycled through system design, significantly reducing preparation cost and environmental emissions.

[0316] In summary, the catalyst preparation method not only significantly improves the synergistic effect between copper species and activated carbon, forms a catalytic center with stable structure and good dispersion, but also effectively avoids impurity interference, improves the selectivity, efficiency of the catalytic reaction, and the accuracy of the final detection.

[0317] The technical features of the above-described embodiments can be combined in any manner. For the sake of brevity, not all possible combinations of the technical features in the above-described embodiments are listed, however, as long as the combinations of the technical features do not contradict each other, they should be considered to be within the scope of the present disclosure.

[0318] Those skilled in the art will appreciate that, without departing from the concept of the present disclosure, a number of variations and modifications can be made, and these should be considered to be within the scope of the present disclosure, which is defined by the appended claims.

Claims

1. A method for detecting decryption of a chemical fiber encrypted using a metal oxide, characterized by, The detection method is: After mixing the chemical fibers to be tested with the catalyst, high-temperature decomposition treatment is performed; then the catalyst is removed by screening to obtain solid powder; whether the solid powder contains metal ions is rapidly characterized by a fluorescence agent; and the ion species and content are obtained by measuring the fluorescence emission spectrum; the main detection method is a combination detection strategy of fluorescence spectroscopy plus ICP-MS auxiliary verification, and ICP-MS is used as a supplementary means for periodic verification of the accuracy of the main detection method, or for quantitative analysis of complex matrix, suspicious results or trace metals; The preparation method of the catalyst is: S1, after mixing copper oxide and activated carbon uniformly, the system is placed in a sealed container, the air in the system is discharged, nitrogen and hydrogen chloride gas are filled in according to a certain proportion, under heating conditions, hydrogen chloride gas reacts with copper oxide to generate copper chloride and water, and the generated copper chloride is adsorbed on the activated carbon in water; S2, under heating conditions, continue to introduce nitrogen, and take away the excess hydrogen chloride gas and the hydrogen chloride gas desorbed from the activated carbon; S3, continue to introduce oxygen and nitrogen, oxidize copper chloride to copper oxide, continue to introduce nitrogen to take away the excess oxygen and chlorine, and cool the system to room temperature, finally wash, dry, sieve, and microwave to obtain the activated carbon catalyst loaded with copper oxide.

2. The method of claim 1, wherein the metal oxide-encrypted chemical fiber is decrypted by a method comprising: In step S1, the mass ratio of copper oxide to activated carbon is 1: (5-10); ​ The volume ratio of hydrogen chloride gas to nitrogen is 1: (6-10), the flow rate of HCl gas is 20-40 mL / min, and the flow rate of N2 is 120-400 mL / min; In step S1, the heating condition is 180-220 ℃.

3. The decryption detection method for chemical fibers encrypted with metal oxides according to claim 1, characterized in that, In step S2, the heating condition is 180-220 ℃; In step S3, the process of oxidizing copper chloride to copper oxide includes a low-temperature oxidation stage and a medium-temperature oxidation stage in sequence; In the low-temperature oxidation stage, the gas introduced into the system includes 4.5%-5.5% O2, 0.8%-1.2% water vapor and 93.3%-94.7% N2 in terms of volume percentage, wherein the water vapor is contained in N2, the total flow rate of the gas introduced in the low-temperature oxidation stage is 110-130 mL / min, the temperature is controlled at 220-240 ℃, and the duration is 55-65 min; In the medium-temperature oxidation stage, the gas introduced into the system includes 7.5%-8.5% O2 and 91.5%-92.5% N2 in terms of volume percentage, the total volume flow rate of the gas introduced in the medium-temperature oxidation stage is 140-160 mL / min, the flow rate of O2 is 10-14 mL / min, the flow rate of N2 is 126-150 mL / min, the temperature is controlled at 260-280 ℃, and the duration is 15-25 min; In the process of cooling to room temperature, pure N2 with a volume ratio of ≥99.99% is introduced, the flow rate is 190-210 mL / min, and the duration is until the system is cooled to 20-30 ℃.

4. The method of claim 1, wherein the metal oxide-encrypted chemical fiber is decrypted by a chemical fiber decryption method using a metal oxide, and In step S3, the activated carbon loaded with copper oxide obtained after sieving has a mesh size of 30-50, and the activated carbon has a pore size of 2-50 nm and a specific surface area of 1000 m2 / g or more; ​ The microwave treatment is performed in a nitrogen atmosphere, the microwave power is 500-700 W, the microwave treatment time is 5-20 min, and the microwave treatment temperature is 120-150 DEG C; during the microwave treatment, nitrogen gas is continuously introduced, the nitrogen gas is introduced throughout the process, and after the microwave treatment is completed, the nitrogen gas is continuously introduced to cool for 10-15 min.

5. The method of claim 1, wherein the metal oxide-encrypted chemical fiber is decrypted by a chemical fiber decryption method, and In the high-temperature decomposition treatment, the catalyst is used in an amount of 5-10 times the mass of the chemical fiber to be tested, and the high-temperature decomposition treatment is performed at a temperature of 400-550 DEG C in an oxygen and nitrogen atmosphere, wherein the volume ratio of oxygen to nitrogen is 20-30:80-70, and the total flow rate of oxygen and nitrogen is maintained at 200-400 mL / min. ​ 6. The method of claim 1, wherein the metal oxide-encrypted chemical fiber is decrypted by a chemical fiber decryption method, and the chemical fiber decryption method is characterized by: The sieving process uses a 50-mesh sieve, and the remaining solid powder with a small particle size is subjected to fluorescence agent characterization.

7. The decryption detection method for chemical fibers encrypted with metal oxides according to claim 1, characterized in that, The fluorescence agent is a porphyrin fluorescence agent solution, the porphyrin fluorescence agent in the porphyrin fluorescence agent solution is a mixture of tetra(4-carboxyphenyl)porphyrin, tetra(4-sulfonic acid phenyl)porphyrin, and octaethylporphyrin in a mass ratio of 3:(4.5-5.5):(1.5-2.5), and the solvent in the porphyrin fluorescence agent solution is a mixed solvent of water, ethanol, and dimethyl sulfoxide, wherein the volume ratio of water, ethanol, and DMSO is 5:(2.5-3.5):(1.5-2.5).

8. The method of claim 1, wherein the metal oxide-encrypted chemical fiber is decrypted by a method comprising: The method for measuring the fluorescence emission spectrum is as follows: after the solid powder is dissolved in an acid solution, ultrasonic treatment and filtration are performed, then the fluorescence agent is mixed, the pH is adjusted, ultrasonic treatment is performed again, the reaction is allowed to stand, and finally the sample to be tested is obtained by filtration; the fluorescence emission spectrum is measured using the sample to be tested, the fluorescence intensity and peak position data of different samples are recorded, and the metal species is determined by comparing with the known standard metal ion-porphyrin complex fluorescence spectrum; ​ A standard curve and a regression equation are established to establish the relationship between the metal concentration and the fluorescence intensity; the fluorescence intensity of the unknown sample is substituted into the regression equation to calculate the metal concentration; if there is spectral peak overlap, the ultraviolet absorption spectrum is used for identification; The qualitative and quantitative tests of metal elements are realized.

9. The method of claim 8, wherein the metal oxide-encrypted chemical fiber is decrypted by applying a magnetic field to the metal oxide-encrypted chemical fiber. The process conditions for ultrasonic treatment after the solid powder is dissolved in an acid solution are as follows: the ultrasonic treatment power is 190-210 W, ultrasonic treatment is first performed at 50-55 DEG C for 10-20 min, then ultrasonic treatment is performed at 50-60 DEG C for 10-30 min, and then 0.22 mu m filter membrane filtration is performed to remove unsolved particles; The process conditions for ultrasonic treatment after the fluorescence agent is added and the pH is adjusted are as follows: the ultrasonic treatment power is 140-160 W, ultrasonic treatment is first performed at 23-28 DEG C for 5-10 min, then ultrasonic treatment is performed at 50-60 DEG C for 10-30 min, and then the reaction is allowed to stand in the dark for 20-40 min; 0.22 mu m filter membrane filtration is performed to remove unsolved particles, and a clear porphyrin fluorescence agent-metal ion reaction solution is obtained, which is the sample to be tested.

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