Method for monitoring degradation process of organic matters containing carbon, hydrogen, nitrogen and chlorine

Abstract

The invention provides a method for monitoring the degradation process of 3-chloroaniline, and relates to the technical field of water environment pollution remediation. According to the method, by combining multi-dimensional monomer isotope fractionation characteristics and experimental test results, theoretical calculation and experimental test are combined, possible degradation ways, degradation mechanisms and environmental attribution of 3-chloroaniline are deduced, and the results are complete and accurate. Compared with a mode of capturing and degrading intermediate products and free radicals only through a test means so as to reversely deduce a degradation pathway, the monitoring method provided by the invention can well make up the defects of experimental tests, deeply understand a degradation mechanism, more scientifically and reliably analyze the degradation pathway, the mechanism and the environmental destination of the pollutant 3-chloroaniline, and has a good application prospect. Key steps are favorably controlled, and the development of a high-efficiency and low-cost remediation technology for the polluted water environment is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of water environment pollution remediation, and in particular to a method for monitoring the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine. Background Art

[0002] 3-Chloroaniline (3-CA) is an important amine compound, which is widely used in industrial production of dyes, cosmetics, pharmaceutical products, herbicides and organic metallurgical reagent byproducts. Previous studies have shown that 3-CA accumulates in large quantities in a variety of environmental matrices such as sludge, soil and surface water. Due to its toxicity and difficulty in hydrolysis, it poses a great potential risk to humans and ecosystems.

[0003] Photoinduced degradation, direct photolysis, and photolysis promoted by naturally occurring photocatalysts are considered to be important pathways for the transformation of organic pollutants in the natural environment. In particular, dissolved organic matter (DOM) can be used as an important photosensitizer to degrade organic pollutants. Among them, humic substances (HS) are the main components of DOM, have color development, and are the main source of photochemically generated oxidants in the environment. HS can strongly absorb light and form a large number of active substances, such as singlet oxygen, triplet ( 3 HS*) and hydroxyl radicals (·OH) can effectively promote the degradation of organic compounds. Studies have shown that ·OH and triplet ( 3 HS * ) plays a vital role in the photochemical reactions of organic pollutants such as phthalates and methyl tert-butyl ether in surface water. Many research papers explain the degradation process of organic pollutants by identifying the transformation products (TPs) during the degradation of organic pollutants by gas chromatography-mass spectrometry (GC / MS) or liquid chromatography-mass spectrometry (HPLC / MS). However, since the research mechanism relying on the chemical fingerprint of degradation products is often uncertain, it is difficult to reach a consensus on the research conclusions, which brings difficulties to clarify the degradation mechanism and environmental fate of organic pollutants and is not conducive to in-depth research on the environmental behavior of organic pollutants. In addition, physical influences (such as dilution, volatilization and adsorption) may also lead to inaccurate concentration measurements of organic pollutants and incomplete types of intermediates detected, making it impossible to accurately infer their transformation mechanisms. Therefore, it is of great significance to explore new methods to explain the transformation pathways of organic pollutants in a more scientific and efficient way.

[0004] Compound-specific monomer isotope analysis (CSIA) is a widely used reaction characterization technique in environmental science. It can not only quantitatively study the transformation of organic pollutants in the environment, but also help to study the underlying mechanism of the transformation process. By analyzing the changes in the multi-isotope (εC, εH, εN and εCl) differentiation pattern, the spatiotemporal migration and transformation of target organic matter can be monitored. Isotope fractionation is based on the presence of heavy isotopes (such as 2 H. 13 C.15 N or 37 Cl) and light isotopes (such as 1 H. 12 C. 14 N or 35 Cl) molecules react at slightly different rates in the isotope-sensitive rate-limiting step. The apparent kinetic isotope effect (AKIE) allows for rate limiting steps prior to transition state analysis of bond cleavage reactions. Therefore, CSIA can provide direct evidence for exploring the first irreversible step in the degradation mechanism of pollutants and can provide insight into transformation pathways without determining the transformation products (TPs). Analytical multi-element isotopic fractionation can be used to probe the location of chemical bond change reactions in specific molecular entities and determine the relative contribution of various reaction pathways when organic molecules undergo parallel decomposition reactions. Specific reaction locations within a molecule can be determined by correlation of isotopic fractionation of multi-element bond change reactions. In addition, monitoring changes in multi-element isotopic composition provides the opportunity to determine the relative contribution of different reaction pathways, as bond change reactions of various isotopes can be correlated to determine the specific location of the reaction in the molecule. CSIA has been used to determine the direct photolysis pathway of 3-CA. However, the existing direct photolysis pathway of 3-CA determined by CSIA is not complete enough to accurately infer its transformation mechanism. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method for monitoring the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine. The detection method provided by the present invention can realize in-depth exploration of the degradation mechanism of organic matter containing carbon, hydrogen, nitrogen and chlorine by multi-dimensional isotope fractionation of hydrogen, carbon, nitrogen and chlorine, and the monitoring results are complete and accurate.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for monitoring the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine, comprising the following steps:

[0008] Degrading an aqueous phase containing organic matter containing carbon, hydrogen, nitrogen and chlorine, and performing liquid-liquid extraction on degradation reaction liquids at different degradation times using an organic extractant to obtain organic phases at a series of time points; the degradation includes photosensitization degradation and / or advanced oxidation degradation;

[0009] Performing gas phase-mass spectrometry analysis on the organic phase at the series of time points to obtain the intermediate product structures of the carbon, hydrogen, nitrogen and chlorine-containing organic matter at different degradation times;

[0010] Performing stable monomer isotope detection on the organic phase at the series of time points to obtain changes in isotope ratios of carbon, hydrogen, nitrogen and chlorine during the degradation process along with the degree of degradation;

[0011] Based on the degradation kinetic characteristic curve of organic matter containing carbon, hydrogen, nitrogen and chlorine and the change of the isotope ratio with the degree of degradation, the isotope enrichment factors of carbon, hydrogen, nitrogen and chlorine are obtained according to the Rayleigh equation, and the chemical bond breakage results of organic matter containing carbon, hydrogen, nitrogen and chlorine during the degradation process are obtained according to the isotope enrichment factors;

[0012] According to the intermediate product structures of the carbon, hydrogen, nitrogen and chlorine-containing organic matter at different degradation times and the chemical bond breaking results of the carbon, hydrogen, nitrogen and chlorine-containing organic matter, the monitoring results of the degradation process of the carbon, hydrogen, nitrogen and chlorine-containing organic matter are obtained; the monitoring results of the degradation process include one or more of the degradation pathway, degradation mechanism and environmental fate.

[0013] Preferably, a degradation agent is added during the degradation process, the degradation agent includes one or more of humic acid, Bengal rose red, 4-methoxybenzaldehyde and hydrogen peroxide, and the wavelength of the degradation is ≥320nm;

[0014] The mass ratio of the organic matter containing carbon, hydrogen, nitrogen and chlorine in the aqueous phase containing organic matter containing carbon, hydrogen, nitrogen and chlorine to the mass ratio of the degradation reagent is 0.8-1 mmol: 0.1-0.5 g;

[0015] The organic matter containing carbon, hydrogen, nitrogen and chlorine includes chloroaniline and / or substituted chloroaniline; the substituted chloroaniline includes nitrochloroaniline and / or hydroxychloroaniline.

[0016] Preferably, the organic extractant comprises halogenated hydrocarbons and / or alkanes;

[0017] The liquid-liquid extraction includes oscillation extraction;

[0018] The temperature of the liquid-liquid extraction is 6-10° C., and the time is 4-8 hours.

[0019] Preferably, the conditions for gas phase separation in the gas phase-mass spectrometry analysis include: the chromatographic column includes a (5%-phenyl)-methylpolysiloxane capillary column, the injection mode is a fractionation mode, the fractionation ratio is 1:2-5, the injection volume is 1-5 μL, the injection port temperature is 220-260°C, the helium flow rate is 1.5 mL / min, and the heating program is: the initial temperature is maintained at 60°C for 2 minutes, the temperature is increased to 180°C at a rate of 15°C / min and maintained for 2 minutes, and the temperature is increased to 290°C at a rate of 15°C / min and maintained for 5 minutes.

[0020] Preferably, the mass spectrometry analysis conditions in the gas phase-mass spectrometry analysis include: full scan mode, a transmission line temperature of 280°C, and an ion source temperature of 280°C.

[0021] Preferably, the stable monomer isotope detection comprises the following steps:

[0022] The organic phases at the series of time points are subjected to gas chromatography separation, and the obtained gas phase components are subjected to oxidation tube-isotope ratio mass spectrometry detection, pyrolysis tube-isotope ratio mass spectrometry detection, dual oxidation tube-isotope ratio mass spectrometry detection and multi-collector inductively coupled plasma mass spectrometry detection, respectively, to obtain the changes of isotope ratios of carbon, hydrogen, nitrogen and chlorine with the degree of degradation;

[0023] During the stable monomer isotope detection process, the nitrogen isotope signal value is greater than 0.1V, the hydrogen isotope signal value is greater than 0.5V, the carbon isotope signal value is greater than 0.1V, and the chlorine isotope signal value is greater than 2.5V.

[0024] Preferably, the conditions for gas chromatography separation include: the chromatographic column includes a (5%-phenyl)-methylpolysiloxane capillary column, the injection mode is a fractionation mode, the fractionation ratio is 1:2-5, the injection volume is 1-5 μL, the injection port temperature is 220-260°C, the helium flow rate is 1.5 mL / min, and the heating program is: the initial temperature is maintained at 60°C for 2 minutes, the temperature is increased to 180°C at a rate of 15°C / min and maintained for 2 minutes, and the temperature is increased to 290°C at a rate of 15°C / min and maintained for 5 minutes.

[0025] Preferably, the conditions for the oxidation tube-isotope ratio mass spectrometry detection include: the temperature of the oxidation tube is 1000°C;

[0026] The conditions for the pyrolysis tube-isotope ratio mass spectrometry detection include: the temperature of the pyrolysis tube is 1200°C;

[0027] The conditions for the dual oxidation tube-isotope ratio mass spectrometry detection include: the dual oxidation tubes are two oxidation tubes connected in series, and the temperatures of the two oxidation tubes connected in series are 1000° C. and 600° C. respectively;

[0028] The conditions for the multi-collector inductively coupled plasma mass spectrometry detection include: operating in a low-resolution mode, wherein the low-resolution mode is m / Δm=400.

[0029] Preferably, the method for obtaining the degradation kinetic characteristic curve of carbon, hydrogen, nitrogen and chlorine-containing organic matter comprises the following steps: testing the concentration of carbon, hydrogen, nitrogen and chlorine-containing organic matter in the organic phase at the series of time points, taking the degradation time as the independent variable and the concentration of carbon, hydrogen, nitrogen and chlorine-containing organic matter as the dependent variable, to obtain the degradation kinetic characteristic curve of carbon, hydrogen, nitrogen and chlorine-containing organic matter.

[0030] Preferably, the Rayleigh equation is as shown in Formula 1:

[0031]

[0032] Among them, ε is the isotopic enrichment factor, δ0 and δ tare the isotopic compositions of organic matter containing carbon, hydrogen, nitrogen and chlorine at degradation time 0 and t, respectively. t are the concentrations of organic matter containing carbon, hydrogen, nitrogen and chlorine at degradation time 0 and t respectively.

[0033] The present invention samples at different time points of degradation of organic matter containing carbon, hydrogen, nitrogen and chlorine, uses an organic extractant, and adopts a liquid-liquid extraction method to extract the target pollutant to the organic phase, and performs stable monomer isotope monitoring on the extracted samples, and determines the change of the isotope ratio of carbon, hydrogen, nitrogen and chlorine in the degradation process with the degree of degradation, and combines the degradation kinetic characteristic curve of organic matter containing carbon, hydrogen, nitrogen and chlorine, and comprehensively calculates the multidimensional stable isotope enrichment factor of carbon, hydrogen, nitrogen and chlorine in the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine, and infers the chemical bond breaking of organic matter containing carbon, hydrogen, nitrogen and chlorine in the above-mentioned degradation process, and then combines the structure of the degradation intermediate product monitored in the reaction process, and further explores the degradation pathway, mechanism and environmental fate of organic matter containing carbon, hydrogen, nitrogen and chlorine in the water environment. The present invention combines theoretical calculation with experimental test by combining the multidimensional monomer isotope fractionation characteristics and experimental test results, and infers the possible degradation pathway, degradation mechanism and environmental fate of organic matter containing carbon, hydrogen, nitrogen and chlorine, and the result is complete and accurate.

[0034] Compared with the method of only capturing degradation intermediates and free radicals through testing means and then inferring the degradation pathway, the monitoring method provided by the present invention can well make up for the shortcomings of experimental testing, deeply understand the degradation mechanism, and more scientifically and reliably analyze the degradation pathway, mechanism and environmental fate of carbon, hydrogen, nitrogen and chlorine-containing organic matter, which is conducive to controlling key steps and promoting the development of efficient and low-cost remediation technology for polluted water environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the degradation kinetic characteristic curve of 3-chloroaniline;

[0036] Figure 2 This is the fitting diagram of the carbon isotope Rayleigh equation for the photosensitized degradation of 3-chloroaniline;

[0037] Figure 3 This is the fitting diagram of hydrogen isotope Rayleigh equation for photosensitized degradation of 3-chloroaniline;

[0038] Figure 4 This is the fitting diagram of the nitrogen isotope Rayleigh equation for the photosensitized degradation of 3-chloroaniline;

[0039] Figure 5 This is the fitting diagram of the chlorine isotope Rayleigh equation for the photosensitized degradation of 3-chloroaniline;

[0040] Figure 6 This is the fitting diagram of the carbon-chlorine two-dimensional isotope composition change during the photosensitive degradation process of 3-chloroaniline;

[0041] Figure 7 This is the fitting diagram of the carbon-nitrogen two-dimensional isotope composition change during the photosensitized degradation process of 3-chloroaniline;

[0042] Figure 8 This is the fitting diagram of the carbon-hydrogen two-dimensional isotope composition change during the photosensitive degradation process of 3-chloroaniline;

[0043] Fig. 9 This is a diagram of the degradation mechanism of 3-chloroaniline in the photosensitizer system. DETAILED DESCRIPTION

[0044] The present invention provides a method for monitoring the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine, comprising the following steps:

[0045] Degrading an aqueous phase containing organic matter containing carbon, hydrogen, nitrogen and chlorine, and performing liquid-liquid extraction on degradation reaction liquids at different degradation times using an organic extractant to obtain organic phases at a series of time points; the degradation includes photosensitization degradation and / or advanced oxidation degradation;

[0046] Performing gas phase-mass spectrometry analysis on the organic phase at the series of time points to obtain the intermediate product structures of the carbon, hydrogen, nitrogen and chlorine-containing organic matter at different degradation times;

[0047] Performing stable monomer isotope detection on the organic phase at the series of time points to obtain changes in isotope ratios of carbon, hydrogen, nitrogen and chlorine during the degradation process along with the degree of degradation;

[0048] Based on the degradation kinetic characteristic curve of organic matter containing carbon, hydrogen, nitrogen and chlorine and the change of the isotope ratio with the degree of degradation, the isotope enrichment factors of carbon, hydrogen, nitrogen and chlorine are obtained according to the Rayleigh equation, and the chemical bond breakage results of organic matter containing carbon, hydrogen, nitrogen and chlorine during the degradation process are obtained according to the isotope enrichment factors;

[0049] According to the intermediate product structures of the carbon, hydrogen, nitrogen and chlorine-containing organic matter at different degradation times and the chemical bond breaking results of the carbon, hydrogen, nitrogen and chlorine-containing organic matter, the monitoring results of the degradation process of the carbon, hydrogen, nitrogen and chlorine-containing organic matter are obtained; the monitoring results of the degradation process include one or more of the degradation pathway, degradation mechanism and environmental fate.

[0050] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0051] The present invention degrades an aqueous phase containing organic matter containing carbon, hydrogen, nitrogen and chlorine, and uses an organic extractant to perform liquid-liquid extraction on degradation reaction liquids at different degradation times to obtain organic phases at a series of time points; the degradation includes photosensitized degradation and / or advanced oxidation degradation.

[0052] In the present invention, the active substances produced in the advanced oxidation degradation preferably include hydroxyl radicals. In the present invention, a degradation agent is added during the degradation process, and the degradation agent preferably includes one or more of humic acid, Bengal rose red, 4-methoxybenzaldehyde and hydrogen peroxide; the wavelength of the degradation is preferably ≥320nm, more preferably 320-400nm.

[0053] In the present invention, the concentration of the organic matter containing carbon, hydrogen, nitrogen and chlorine in the organic matter containing carbon, hydrogen, nitrogen and chlorine aqueous phase is preferably 0.8-1.0 mM (mmol / L), and in a specific embodiment, it can be 0.8 mM, 0.9 mM or 1 mM; the organic matter containing carbon, hydrogen, nitrogen and chlorine preferably includes chloroaniline and / or substituted chloroaniline; the substituent in the substituted chloroaniline preferably includes nitro and / or hydroxyl, and the substitution site of the substituent preferably includes one or more of ortho, meta and para positions; the chloroaniline in the chloroaniline and substituted chloroaniline preferably includes one or more of 2-chloroaniline, 3-chloroaniline and 4-chloroaniline. In the present invention, the organic matter containing carbon, hydrogen, nitrogen and chlorine aqueous phase preferably includes a polluted water body containing organic matter containing carbon, hydrogen, nitrogen and chlorine.

[0054] In the present invention, the ratio of the amount of the organic carbon, hydrogen, nitrogen, chlorine and organic matter in the aqueous phase containing organic carbon, hydrogen, nitrogen, chlorine and organic matter to the mass of the degradation reagent is preferably 0.8-1 mmol: 0.1-0.5 g, and in a specific embodiment it can be 0.8 mmol: 0.1 g, 0.8 mmol: 0.2 g, 0.8 mmol: 0.3 g, 0.8 mmol: 0.5 g, 0.9 mmol: 0.1 g, 0.9 mmol: 0.2 g, 0.9 mmol: 0.3 g, 0.9 mmol: 0.4 g, 0.9 mmol: 0.5 g, 1 mmol: 0.1 g, 1 mmol: 0.2 g, 1 mmol: 0.3 g, 1 mmol: 0.4 g or 1 mmol: 0.5 g.

[0055] In the present invention, the organic extractant preferably includes halogenated hydrocarbons and / or alkanes; the halogenated hydrocarbons preferably include dichloromethane; the alkanes preferably include n-hexane. In the present invention, the volume ratio of the degradation reaction solution to the organic extractant is preferably 1:0.05-0.5, and in specific embodiments can be 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.4 or 1:0.5.

[0056] In the present invention, the liquid-liquid extraction preferably includes oscillation extraction; the temperature of the liquid-liquid extraction is preferably 6-10°C, and in a specific embodiment it can be 6°C, 7°C, 8°C, 9°C or 10°C; the time of the liquid-liquid extraction is preferably 4-8h, and in a specific embodiment it can be 4h, 5h, 6h, 7h or 8h.

[0057] After obtaining the organic phases at a series of time points, the present invention performs gas phase-mass spectrometry analysis on the organic phases at the series of time points to obtain the intermediate product structures of different degradation times of organic matter containing carbon, hydrogen, nitrogen and chlorine.

[0058] In the present invention, the conditions for gas phase separation in the gas phase-mass spectrometry analysis preferably include: the chromatographic column includes a (5%-phenyl)-methyl polysiloxane capillary column, which can be a BPX-5 capillary column (size is 60m×0.25mm×0.25μm) in a specific embodiment; the injection mode is a fractionation mode; the fractionation ratio is 1:2-5, which can be 1:2, 1:3, 1:4 or 1:5 in a specific embodiment; the injection volume is 1-5μL, which can be The injection port temperature is 220-260°C, and in specific embodiments, it can be 220°C, 230°C, 240°C, 250°C or 260°C; the helium flow rate is 1.5mL / min, and the heating program is as follows: the initial temperature is maintained at 60°C for 2min, heated to 180°C at a rate of 15°C / min and maintained for 2min, heated to 290°C at a rate of 15°C / min and maintained for 5min.

[0059] In the present invention, the mass spectrometry analysis conditions of the gas phase-mass spectrometry analysis preferably include: full scan mode, a transmission line temperature of 280°C, and an ion source temperature of 280°C.

[0060] When obtaining the degradation intermediate product in the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine, the present invention uses the organic matter containing carbon, hydrogen, nitrogen and chlorine as the starting compound for analysis.

[0061] After obtaining the organic phases at a series of time points, the present invention performs stable monomer isotope detection on the organic phases at the series of time points to obtain changes in the isotope ratios of carbon, hydrogen, nitrogen and chlorine during the degradation process along with the degree of degradation.

[0062] In the present invention, the stable monomer isotope detection preferably includes the following steps: performing gas chromatography separation on the organic phase at the series of time points, and performing oxidation tube-isotope ratio mass spectrometry detection, cracking tube-isotope ratio mass spectrometry detection, dual oxidation tube-isotope ratio mass spectrometry detection and multi-collector inductively coupled plasma mass spectrometry detection on the obtained gas phase components, respectively, to obtain the changes in the isotope ratios of carbon, hydrogen, nitrogen and chlorine with the degree of degradation; in the process of the stable monomer isotope detection, the nitrogen isotope signal value is greater than 0.1V, the hydrogen isotope signal value is greater than 0.5V, the carbon isotope signal value is greater than 0.1V, and the chlorine isotope signal value is greater than 2.5V.

[0063] In the present invention, the isotope ratio is the ratio of the abundance of heavy isotope atoms to the abundance of light isotope atoms of a certain element.

[0064] In the present invention, the conditions for gas chromatography separation preferably include: the chromatographic column includes a (5%-phenyl)-methyl polysiloxane capillary column, which can be a BPX-5 capillary column (size: 60m×0.25mm×0.25μm) in a specific embodiment; the injection mode is a fractionation mode; the fractionation ratio is 1:2-5, which can be 1:2, 1:3, 1:4 or 1:5 in a specific embodiment; the injection volume is 1-5μL, which can be 1μL in a specific embodiment. L, 2μL, 3μL, 4μL or 5μL; the injection port temperature is 220-260°C, and in specific embodiments can be 220°C, 230°C, 240°C, 250°C or 260°C; the helium flow rate is 1.5mL / min, and the heating program is: the initial temperature is maintained at 60°C for 2min, heated to 180°C at a rate of 15°C / min and maintained for 2min, heated to 290°C at a rate of 15°C / min and maintained for 5min.

[0065] In the present invention, the conditions for the oxidation tube-isotope ratio mass spectrometry detection preferably include: the temperature of the oxidation tube is 1000°C.

[0066] In the present invention, the conditions for the pyrolysis tube-isotope ratio mass spectrometry detection preferably include: the temperature of the pyrolysis tube is 1200°C.

[0067] In the present invention, the conditions for the dual oxidation tube-isotope ratio mass spectrometry detection preferably include: the dual oxidation tubes are two oxidation tubes connected in series, and the temperatures of the two oxidation tubes connected in series are 1000° C. and 600° C. respectively.

[0068] In the present invention, the conditions for the multi-collector inductively coupled plasma mass spectrometry detection preferably include: operating in a low-resolution mode, wherein the low-resolution mode is m / Δm=400.

[0069] After obtaining the change of isotope ratio with the degree of degradation, the present invention obtains the isotope enrichment factors of carbon, hydrogen, nitrogen and chlorine according to the Rayleigh equation based on the degradation kinetic characteristic curve of the organic matter containing carbon, hydrogen, nitrogen and chlorine and the change of the isotope ratio with the degree of degradation, and obtains the result of chemical bond breakage of the organic matter containing carbon, hydrogen, nitrogen and chlorine during the degradation process according to the isotope enrichment factors.

[0070] In the present invention, the method for obtaining the degradation kinetic characteristic curve of carbon, hydrogen, nitrogen and chlorine-containing organic matter comprises the following steps: testing the concentration of carbon, hydrogen, nitrogen and chlorine-containing organic matter in the organic phase at the series of time points, taking the degradation time as the independent variable and the concentration of carbon, hydrogen, nitrogen and chlorine-containing organic matter as the dependent variable, to obtain the degradation kinetic characteristic curve of carbon, hydrogen, nitrogen and chlorine-containing organic matter.

[0071] In the present invention, the Rayleigh equation is as shown in Formula 1:

[0072]

[0073] Among them, ε is the isotopic enrichment factor, δ0 and δ t are the isotopic compositions of organic matter containing carbon, hydrogen, nitrogen and chlorine at degradation time 0 and t, respectively. t are the concentrations of organic matter containing carbon, hydrogen, nitrogen and chlorine at degradation time 0 and t, respectively. The present invention uses the Rayleigh equation and the degradation kinetic curve of organic matter containing carbon, hydrogen, nitrogen and chlorine to calculate the isotopic enrichment factors of carbon, hydrogen and nitrogen in the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine, and can achieve the characterization of isotope fractionation characteristics.

[0074] In the present invention, the isotope enrichment factors of carbon, hydrogen, nitrogen and chlorine are obtained according to the Rayleigh equation from the degradation kinetic characteristic curve of organic matter containing carbon, hydrogen, nitrogen and chlorine and the change of the isotope ratio with the degree of degradation. Specifically, the degradation kinetic characteristic curve of organic matter containing carbon, hydrogen, nitrogen and chlorine and the characteristic curve of the change of the isotope ratio of organic matter containing carbon, hydrogen, nitrogen and chlorine (i.e. the change of the isotope ratio with the degradation kinetics) are fitted by using the Rayleigh equation to obtain the isotope enrichment factors of carbon, hydrogen, nitrogen and chlorine.

[0075] In the present invention, the chemical bond breaking results of the carbon, hydrogen, nitrogen and chlorine-containing organic matter preferably include the C-Cl, CH and CN bond breaking conditions of the rate-determining step of the carbon, hydrogen, nitrogen and chlorine-containing organic matter. Specifically, the two-dimensional isotope change of C-Cl during the degradation process (∧ C-Cl ), CN two-dimensional isotope variation (∧ C-N ) and CH 2D isotope variation (∧ C-H ), and obtain the chemical bond breaking results of C-Cl, CN and CH respectively. In the present invention, ∧ C-Cl ,∧ C-N and ∧ C-H It is the process of regression fitting of the relative values ​​of carbon and hydrogen isotope changes compared to the initial point at the same sampling point during the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine. When obtaining the change of isotope ratios of carbon, hydrogen, nitrogen and chlorine over time, the present invention focuses on the isotope changes of organic matter containing carbon, hydrogen, nitrogen and chlorine.

[0076] In the present invention, the two-dimensional isotope variation calculation formula is as follows:

[0077] After obtaining the intermediate product structures of different degradation times of organic matter containing carbon, hydrogen, nitrogen, and chlorine and the results of chemical bond rupture of organic matter containing carbon, hydrogen, nitrogen, and chlorine, the present invention obtains the monitoring results of the degradation process of organic matter containing carbon, hydrogen, nitrogen, and chlorine according to the intermediate product structures of different degradation times of organic matter containing carbon, hydrogen, nitrogen, and chlorine and the results of chemical bond rupture of organic matter containing carbon, hydrogen, nitrogen, and chlorine; the monitoring results of the degradation process include one or more of degradation pathways, degradation mechanisms, and environmental fates. The present invention does not specifically limit the specific conversion process of obtaining the monitoring results of the degradation process of organic matter containing carbon, hydrogen, nitrogen, and chlorine with respect to the intermediate product structures of different degradation times of organic matter containing carbon, hydrogen, nitrogen, and chlorine and the results of chemical bond rupture of organic matter containing carbon, hydrogen, nitrogen, and chlorine, and the conversion process well known to those skilled in the art can be used.

[0078] In order to further illustrate the present invention, the monitoring method for the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine provided by the present invention is described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0079] In the following examples, the light source used for photosensitization degradation is: a 320 nm long pass filter is used to remove the light with a wavelength shorter than 320 nm in a 150 W xenon lamp (L2175 model, wavelength 185-2000 nm), which is used as the light source for photosensitization degradation, recorded as UV (320 nm). During the entire photosensitization degradation process, the temperature is maintained at 20° C. by a water bath circulation device.

[0080] In the following examples, the experimental materials and instruments are as follows:

[0081] Experimental materials: 3-chloroaniline (purity above 99.5%), carbon oxidation tube, HTC pyrolysis tube, chromatography grade dichloromethane.

[0082] Instruments: gas phase-single oxidation tube-stable isotope ratio mass spectrometry (GC-C-IRMS), gas phase-double oxidation tube-stable isotope ratio mass spectrometry (GC-CC-IRMS), gas phase-pyrolysis tube-stable isotope ratio mass spectrometry (GC-HTC-IRMS), gas phase-multi-collector inductively coupled plasma mass spectrometry (GC-MC-ICPMS).

[0083] In the following examples, the detection conditions are as follows:

[0084] Gas chromatography conditions: the chromatographic column is a (5%-phenyl)-methylpolysiloxane capillary column BPX-5 (size: 60m×0.25mm×0.25μm), the injection mode is the fractionation mode, the fractionation ratio is 1:5, the injection volume is 1-5μL, the injection port temperature is 260°C, the helium flow rate is 1.5mL / min, and the heating program is: the initial temperature is maintained at 60°C for 2min, the temperature is increased to 180°C at a rate of 15°C / min and maintained for 2min, and the temperature is increased to 290°C at a rate of 15°C / min and maintained for 5min.

[0085] Mass spectrometry conditions in gas chromatography-mass spectrometry: full scan mode, transfer line temperature of 280 °C, ion source temperature of 280 °C.

[0086] The conditions for double oxidation tube-isotope ratio mass spectrometry detection are as follows: the combustion oxidation temperatures of the two oxidation tubes connected in series are 1000° C. (the first oxidation tube) and 600° C. (the second oxidation tube) respectively; the oxidation tube is a ceramic tube and a mixture of NiO and CuO filled in the ceramic tube, and the oxidation tube is oxidized before use to ensure that all carbon in the chloroaniline can be oxidized into carbon dioxide.

[0087] The conditions for single oxidation tube-isotope ratio mass spectrometry detection are as follows: the combustion oxidation temperatures of the two oxidation tubes connected in series are 1000° C. (the first oxidation tube) and 600° C. (the second oxidation tube) respectively; the oxidation tube is a ceramic tube and a mixture of NiO and CuO filled in the ceramic tube, and the oxidation tube is oxidized before use to ensure that all carbon in the chloroaniline can be oxidized into carbon dioxide.

[0088] The conditions for the pyrolysis tube-isotope ratio mass spectrometry detection are as follows: the temperature of the pyrolysis tube is 1200°C.

[0089] The conditions for multi-collector inductively coupled plasma mass spectrometry detection preferably include: the instrument used is Neptune, and it is operated in a low-resolution mode (m / Δm=400).

[0090] During the detection of the m-chloroaniline, the nitrogen isotope signal value is greater than 0.1V, the hydrogen isotope signal value is greater than 0.5V, the carbon isotope signal value is greater than 0.1V, and the chlorine isotope signal value is greater than 2.5V. If the signal value does not meet the above requirements, the concentration of chloroaniline is adjusted to meet the above requirements.

[0091] During the test, each sample was repeated three times to ensure the reproducibility of the test results. The standard deviations of the stable isotope ratios of nitrogen, hydrogen and chlorine met the δ 15 N: ±0.3‰, δ 2 H: ±5‰; δ 13 C: ±0.5‰, δ 37 Cl: ±0.5‰.

[0092] Example 1

[0093] S1. Place a 0.8 mM 3-chloroaniline aqueous solution in a heat-resistant glass cylindrical flask with a quartz window, and degrade it at 20°C and light (320-2000 nm) for 0 h, 3 h, 6 h, 8 h, 10 h, 20 h, 30 h, 55 h, 87 h, 96 h, 120 h and 140 h, respectively. Take 20 mL of the degradation reaction solution at different degradation time points, add 2 mL of dichloromethane, and oscillate at 10°C for 4 h to obtain dichloromethane phases at a series of time points (stored at 4°C before analysis). Use gas chromatography (GC) to test the concentration of 3-chloroaniline in different systems and at different photosensitized degradation times. Take the degradation time as the independent variable and the concentration of 3-chloroaniline as the dependent variable to obtain the degradation kinetic characteristic curve of 3-chloroaniline. The degradation conditions are as follows: (1) no degradation reagent; (2) Rose Bengal (0.1 g / L); (3) Rose Bengal (0.4 g / L); (4) Rose Bengal (0.1 g / L) + N2 atmosphere (denoted as O2-free, as long as stable bubbles are generated after N2 is introduced); (5) 4-methoxybenzaldehyde (4-MBA, 0.1 g / L); (6) hydrogen peroxide (H2O 2， 40mM); (7) humic acid (PPHA, 0.1g / L); (8) humic acid (PPHA, 0.1g / L) + 2,4,6-trimethylphenol (TMP, 0.1g / L); (9) humic acid (PPHA, 0.1g / L) + 2-Propanol (40mM); except for the degradation under N2 atmosphere, the others were degraded under air atmosphere. Control experiment: The experiments under the degradation conditions of (2), (6) and (7) above were carried out in a dark environment.

[0094] GC detection conditions: the chromatographic column is a BPX-5 capillary column (size is 60m×0.25mm×0.25μm); the injection method is the fractionation mode; the fractionation ratio is 1:5; the injection volume is 2μL; the injection port temperature is 250℃; the helium flow rate is 1.5mL / min, and the heating program is: the initial temperature is maintained at 60℃ for 2min, the temperature is increased to 180℃ at a rate of 15℃ / min and maintained for 2min, and the temperature is increased to 290℃ at a rate of 15℃ / min and maintained for 5min.

[0095] Figure 1 3-chloroaniline degradation kinetic characteristic curves under different systems. The results show that in all systems of this embodiment, the degradation rates of 3-chloroaniline are composite pseudo-first-order kinetic characteristic curves. The degradation rate of 3-chloroaniline in the UV light / Bengal rose red system is the fastest, and with the increase of the photosensitizer concentration, the degradation rate gradually accelerates.

[0096] Gas phase isotope mass spectrometry was used to study the changes in the isotope ratios of carbon (GC-C-IRMS), hydrogen (GC-HTC-IRMS), nitrogen (GC-CC-IRMS) and chlorine (GC-MC-ICPMS) of 3-chloroaniline as a function of degradation degree.

[0097] The organic phase at a series of time points was analyzed by gas chromatography-mass spectrometry (GC-MS) to obtain the structures of the main degradation intermediates of 3-chloroaniline at different degradation times (mainly including 2-amino-4-chlorophenol and 3-aminophenol).

[0098] The Rayleigh equation is used to fit the degradation kinetic characteristic curve of 3-chloroaniline and the change of the isotope ratio with the degradation degree, and the isotope enrichment factors of carbon, hydrogen, nitrogen and chlorine are obtained. The chemical bond breakage results of 3-chloroaniline during the degradation process are inferred based on the isotope enrichment factors.

[0099] Figures 2 to 5 These are the Rayleigh equation fitting diagrams of carbon, hydrogen, nitrogen and chlorine isotopes in the photosensitized degradation of 3-chloroaniline. It can be seen that under the action of hydroxyl radicals, 3-chloroaniline shows a gradual depletion of carbon and chlorine isotopes and an enrichment of hydrogen isotopes, but no enrichment of nitrogen isotopes is observed; under the action of triplet states, 3-chloroaniline shows a gradual enrichment of carbon isotopes and a gradual depletion of nitrogen and chlorine isotopes, but no enrichment of hydrogen isotopes is observed.

[0100] The results show that the isotopic enrichment factors of carbon, hydrogen, nitrogen and chlorine in the triplet system of Bengal rose red (0.1g / L) are: C =-0.3±0.2‰, ε H =na‰ (not detected), ε N =2.7±0.5‰ and ε Cl =8.4±3.3‰. The isotopic enrichment factors of carbon, hydrogen, nitrogen and chlorine in the hydroxyl radical system of 3-chloroaniline are: ε C =1.9±0.6‰, ε H =-5.0±2.6‰, ε N = nd‰ (not detected) and ε Cl =11.9±2.9‰. Under the condition of co-existence of triplet state and hydroxyl radical, a completely different multi-isotopic fractionation pattern is shown.

[0101] S3, combined with the isotope enrichment factor in step S2, quantify the C-Cl( Figure 6 )、CN( Figure 7 ) and CH( Figure 8) and the two-dimensional isotope changes of the degradation intermediate products in step S1 are combined to finally determine the degradation mechanism and environmental fate of 3-chloroaniline. The details are as follows:

[0102] (1) Control experiments with H2O2, Rose Bengal, and PPHA in the dark showed no degradation of 3-chloroaniline. When the control experiments were carried out with hydrogen peroxide (H2O2), Rose Bengal, or humic acid (PPHA), the concentration of the residual 3-chloroaniline in the dark remained stable, indicating that no reaction occurred. However, direct photolysis experiments using a 320 nm long pass filter without H2O2, HS, or triplet analysis for irradiation greater than 320 nm showed that the degradation was negligible compared to the photochemical reaction.

[0103] (2) In the direct UV photolysis of 3-chloroaniline, 3-aminophenol was found to be the main conversion product. The main reason may be that 3-chloroaniline forms a singlet species after light absorption, which is then converted to a triplet state through intersystem crossing or to the ground state through internal conversion, as well as fluorescence. Subsequent reactions of the excited state lead to isocyanate dehalogenation in polar solvents and form chloride (Cl - ) and protonated carbene, which reacts with water to form 3-aminophenol ( Fig. 9 ).

[0104] (3) Hydroxyl radicals are the main coexisting free radicals in the humic acid / ultraviolet light system. In the photochemical degradation experiment of hydroxyl radicals, the carbon and chlorine isotope values ​​of 3-chloroaniline showed a depletion trend, indicating the isotope reverse fractionation of 3-chloroaniline. On the contrary, the hydrogen isotope value became more positive, indicating the enrichment of hydrogen isotopes. The main degradation products of hydroxyl radicals are 2-amino-4-chlorophenol and 3-aminophenol. Therefore, the addition of OH to the benzene ring is carried out through parallel degradation pathways. One is that OH adds to the aromatic ring in the pre-reaction step to form a π complex, which may rearrange to a σ complex [3-CA-OH] to form different isomeric OH adducts. O2 addition and subsequent elimination of HO2 radicals (hydrogen peroxide radicals) lead to the formation of stable hydroxy-3-chloroaniline. The parallel pathway is meta-hydroxylation leading to dechlorination. This leads to 2 H. 13 C and 37 The explanation of the two pathways of C fractionation is consistent with the hypothesis of parallel C-Cl and C-H bond changes. 13 C and 37 The inverted combination of Cl isotope effects is a unique observation that may be related to the complex transition states and branch points in the reaction, leading to the formation of two products in the reaction with OH ( Fig. 9 ).

[0105] (4) In the UV / Rose Bengal and O2 sensitization reaction, normal carbon (-0.3±0.2‰) and reverse nitrogen (2.7±0.5‰) and reverse chlorine isotope fractionation (8.4±3.3‰) were observed. In the UV / Rose Bengal / no O2 (N2 atmosphere) reaction system, a larger normal carbon (-1.2±0.2‰) isotope enrichment was observed, but statistically similar reverse nitrogen (4.8±1.0‰) and reverse chlorine isotope fractionation (11.2±6.8‰) were observed. Figures 2 to 5 ). In the presence of O2, the reaction of 3-chloroaniline in the UV / humic acid system produced isotopic enrichment factors for forward carbon (-1.0±0.3‰), reverse hydrogen (7.4±1.7‰) and reverse chlorine (2.3±0.7‰), and the two-dimensional isotopic variation fitting value of CH (Λ C-H ) is -6.5±0.6, and the C-Cl two-dimensional isotope variation fitting value (Λ C-Cl ) value is -1.7±0.2, these results indicate that, compared with Rose Bengal (triplet reaction), humic acid causes the CH bond in 3-chloroaniline molecules to break under simulated visible light (>320nm), while the C-Cl bond changes to a lesser extent. No nitrogen isotope fractionation was detected, indicating that there is no major nitrogen isotope effect ( Fig. 9 ).

[0106] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for monitoring the degradation process of organic matter containing carbon, hydrogen, nitrogen and chlorine, characterized in that: The following steps are involved: Degrading an aqueous phase containing organic matter containing carbon, hydrogen, nitrogen and chlorine, and performing liquid-liquid extraction on degradation reaction liquids at different degradation times using an organic extractant to obtain organic phases at a series of time points; the degradation includes photosensitization degradation and / or advanced oxidation degradation; Performing gas phase-mass spectrometry analysis on the organic phase at the series of time points to obtain the intermediate product structures of the carbon, hydrogen, nitrogen and chlorine-containing organic matter at different degradation times; Performing stable monomer isotope detection on the organic phase at the series of time points to obtain changes in isotope ratios of carbon, hydrogen, nitrogen and chlorine during the degradation process along with the degree of degradation; Based on the degradation kinetic characteristic curve of organic matter containing carbon, hydrogen, nitrogen and chlorine and the change of the isotope ratio with the degree of degradation, the isotope enrichment factors of carbon, hydrogen, nitrogen and chlorine are obtained according to the Rayleigh equation, and the chemical bond breakage results of organic matter containing carbon, hydrogen, nitrogen and chlorine during the degradation process are obtained according to the isotope enrichment factors; According to the intermediate product structures of the carbon, hydrogen, nitrogen and chlorine-containing organic matter at different degradation times and the chemical bond breaking results of the carbon, hydrogen, nitrogen and chlorine-containing organic matter, the monitoring results of the degradation process of the carbon, hydrogen, nitrogen and chlorine-containing organic matter are obtained; the monitoring results of the degradation process include one or more of the degradation pathway, degradation mechanism and environmental fate.

2. The monitoring method according to claim 1, characterized in that: A degradation agent is added during the degradation process, wherein the degradation agent includes one or more of humic acid, Bengal rose red, 4-methoxybenzaldehyde and hydrogen peroxide, and the wavelength of the degradation is ≥320nm; The mass ratio of the organic matter containing carbon, hydrogen, nitrogen and chlorine in the aqueous phase containing organic matter containing carbon, hydrogen, nitrogen and chlorine to the mass ratio of the degradation reagent is 0.8-1 mmol: 0.1-0.5 g; The organic matter containing carbon, hydrogen, nitrogen and chlorine includes chloroaniline and / or substituted chloroaniline; the substituted chloroaniline includes nitrochloroaniline and / or hydroxychloroaniline.

3. The monitoring method according to claim 1, characterized in that: The organic extractant includes halogenated hydrocarbons and / or alkanes; The liquid-liquid extraction includes oscillation extraction; The temperature of the liquid-liquid extraction is 6-10° C., and the time is 4-8 hours.

4. The monitoring method according to claim 1, characterized in that: The conditions for gas phase separation in the gas phase-mass spectrometry analysis include: a chromatographic column includes a (5%-phenyl)-methylpolysiloxane capillary column, an injection mode is a fractionation mode, a fractionation ratio is 1:2-5, an injection volume is 1-5 μL, an injection port temperature is 220-260°C, a helium flow rate is 1.5 mL / min, and a heating program is: an initial temperature of 60°C is maintained for 2 minutes, the temperature is increased to 180°C at a rate of 15°C / min and maintained for 2 minutes, and the temperature is increased to 290°C at a rate of 15°C / min and maintained for 5 minutes.

5. The monitoring method according to claim 1, characterized in that: The mass spectrometry analysis conditions in the gas phase-mass spectrometry analysis include: full scan mode, a transmission line temperature of 280° C., and an ion source temperature of 280° C.

6. The monitoring method according to claim 1, characterized in that: The stable monomer isotope detection comprises the following steps: The organic phases at the series of time points are subjected to gas chromatography separation, and the obtained gas phase components are subjected to oxidation tube-isotope ratio mass spectrometry detection, pyrolysis tube-isotope ratio mass spectrometry detection, dual oxidation tube-isotope ratio mass spectrometry detection and multi-collector inductively coupled plasma mass spectrometry detection, respectively, to obtain the changes of isotope ratios of carbon, hydrogen, nitrogen and chlorine with the degree of degradation; During the stable monomer isotope detection process, the nitrogen isotope signal value is greater than 0.1V, the hydrogen isotope signal value is greater than 0.5V, the carbon isotope signal value is greater than 0.1V, and the chlorine isotope signal value is greater than 2.5V.

7. The monitoring method according to claim 6, characterized in that: The conditions for gas chromatography separation include: a chromatographic column including a (5%-phenyl)-methylpolysiloxane capillary column, an injection mode of a fractionation mode, a fractionation ratio of 1:2-5, an injection volume of 1-5 μL, an injection port temperature of 220-260°C, a helium flow rate of 1.5 mL / min, and a heating program of maintaining an initial temperature of 60°C for 2 minutes, heating to 180°C at a rate of 15°C / min and maintaining for 2 minutes, heating to 290°C at a rate of 15°C / min and maintaining for 5 minutes.

8. The monitoring method according to claim 6, characterized in that: The conditions for the oxidation tube-isotope ratio mass spectrometry detection include: the temperature of the oxidation tube is 1000°C; The conditions for the pyrolysis tube-isotope ratio mass spectrometry detection include: the temperature of the pyrolysis tube is 1200°C; The conditions for the dual oxidation tube-isotope ratio mass spectrometry detection include: the dual oxidation tubes are two oxidation tubes connected in series, and the temperatures of the two oxidation tubes connected in series are 1000° C. and 600° C. respectively; The conditions for the multi-collector inductively coupled plasma mass spectrometry detection include: operating in a low-resolution mode, wherein the low-resolution mode is m / Δm=400.

9. The monitoring method according to claim 1, characterized in that: The method for obtaining the degradation kinetic characteristic curve of organic matter containing carbon, hydrogen, nitrogen and chlorine comprises the following steps: testing the concentration of organic matter containing carbon, hydrogen, nitrogen and chlorine in the organic phase at the series of time points, taking the degradation time as the independent variable and the concentration of organic matter containing carbon, hydrogen, nitrogen and chlorine as the dependent variable, and obtaining the degradation kinetic characteristic curve of organic matter containing carbon, hydrogen, nitrogen and chlorine.

10. The monitoring method according to claim 1, characterized in that: The Rayleigh equation is shown in Formula 1: Among them, ε is the isotopic enrichment factor, δ0 and δ t are the isotopic compositions of organic matter containing carbon, hydrogen, nitrogen and chlorine at degradation time 0 and t, respectively. t are the concentrations of organic matter containing carbon, hydrogen, nitrogen and chlorine at degradation time 0 and t respectively.

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