An experimental apparatus for investigating ozone and hydroxyl radical-mediated CP interfacial reactions.

Abstract

This invention provides an experimental apparatus for investigating the interfacial reaction of CPs mediated by ozone and hydroxyl radicals, comprising: an ozone generator (O3) including a first quartz tube and a 185nm ultraviolet lamp; a hydroxyl radical (·OH) generation unit including a second quartz tube and a 254nm ultraviolet lamp; and a pollutant reactor including a third quartz tube and pollutants coated on the third quartz tube; the first, second, and third quartz tubes are sequentially connected by pipes. This experimental apparatus can obtain O3 at ambient concentration levels, separating the ·OH generation site from the reaction site involved in CP conversion, avoiding the direct photolysis of CPs by ultraviolet light (254nm) and the further reaction of the generated products under ultraviolet light, thereby elucidating the interfacial conversion process and reaction mechanism of CPs mediated by ozone and hydroxyl radicals.

Description

Technical Field

[0001] This invention relates to the field of environmental conversion technology, specifically to an experimental apparatus for investigating the interfacial behavior of CPs mediated by ozone and hydroxyl radicals. Background Technology

[0002] Chlorinated paraffins (CPs) are complex industrial products derived from the chlorination of n-alkanes. They are produced and used in large quantities. Based on carbon chain length, they are classified into short-chain (SCCPs), medium-chain (MCCPs), and long-chain (LCCPs). SCCPs, due to their bioaccumulation, long-distance migration, and biotoxicity, were listed in Appendix A of the Stockholm Convention in 2017 for control. The production of structurally similar MCCPs and LCCPs has been increasing, and they have been widely detected in the environment in recent years. As a class of extremely complex semi-volatile compounds, research on the environmental transformation behavior of CPs is still relatively limited, and research on their transformation in the atmosphere is even more lacking.

[0003] Reactive oxygen species ozone (O3) and hydroxyl radicals (·OH) have been reported to participate extensively in the transformation of small molecule compounds in the atmospheric environment. However, the inventors of this application have found in their research that existing work exploring the transformation of O3 and ·OH in atmospheric pollutants uses ionized spray to deliver droplets or microparticles through the reaction site of ·OH, which is not conducive to exploring the microscopic interfacial reaction mechanism. Furthermore, the components that generate ·OH using ultraviolet light also serve as the reaction site for pollutants, and the ultraviolet light used may participate in the further transformation of pollutants, which is not conducive to the mechanistic analysis of the transformation behavior of reactive oxygen species in CPs. Therefore, there is currently no suitable reaction method and device for exploring the reaction process and transformation mechanism of O3 / ·OH reactive oxygen molecules with CPs at environmental levels. Summary of the Invention

[0004] This application provides an apparatus and method for conducting research on the interfacial behavior of CPs mediated by O3 and ·OH. The purpose is to provide an experimental apparatus and method for exploring the reaction process and transformation mechanism of CPs under the action of reactive oxygen species (O3 and ·OH), to provide basic data for elucidating the environmental behavior of CPs, and thus to play a role in comprehensively assessing the environmental risks of CPs.

[0005] To solve the above-mentioned technical problems, the technical solution proposed in this application is as follows:

[0006] This invention provides an experimental apparatus for investigating ozone and hydroxyl radical-mediated CPs interfacial reactions, comprising:

[0007] An ozone (O3) generator, the ozone (O3) generator comprising a first quartz tube and a 185nm ultraviolet lamp;

[0008] A hydroxyl radical (·OH) generating unit, wherein the hydroxyl radical (·OH) generating unit includes a second quartz tube and a 254nm ultraviolet lamp tube;

[0009] A reactor for CPs, the reactor for CPs comprising a third quartz tube and CPs coated on the third quartz tube;

[0010] The first quartz tube, the second quartz tube, and the third quartz tube are connected sequentially through a pipeline.

[0011] Furthermore, it also includes a nitrogen input section, which is connected to the second quartz tube via a pipeline.

[0012] Furthermore, it also includes a product absorption section, which is connected to the third quartz tube via a pipeline and contains an absorbent.

[0013] Furthermore, it also includes an O3 detector and a humidity detection device installed between the product absorption section and the third quartz tube.

[0014] Furthermore, the absorbent comprises hexane / acetone and / or methanol in a volume ratio of 1:1.

[0015] On the other hand, this application also protects an experimental method for investigating ozone and hydroxyl radical-mediated CPs interfacial reactions according to the aforementioned experimental apparatus, comprising the following steps:

[0016] S1: Preparation of low-concentration ozone (O3): Zero-level air is introduced into the ozone (O3) generator and irradiated with 185nm ultraviolet light to produce 0-100ppb O3;

[0017] S21: Preparation of hydroxyl radical (·OH): The O3 obtained in step S1 is transported to the second quartz tube, and high-purity nitrogen carrying water vapor is introduced through the nitrogen input section to mix with the O3, and then irradiated with 254nm ultraviolet light;

[0018] S31: Reaction of hydroxyl radicals (·OH) with CPs: The hydroxyl radicals (·OH) obtained in step S2 are introduced into the third quartz tube with the gas flow and react with the CPs coated on the third quartz tube.

[0019] On the other hand, this application also protects an experimental method for investigating ozone and hydroxyl radical-mediated CPs interfacial reactions according to the aforementioned experimental apparatus, comprising the following steps:

[0020] S1: Preparation of low-concentration ozone (O3): Zero-level air is introduced into the ozone (O3) generator and irradiated with 185nm ultraviolet light to produce 0-100ppb O3;

[0021] S22: O3 through the second quartz tube: The O3 obtained in step S1 is transported to the second quartz tube, while the 254nm ultraviolet irradiation of the hydroxyl radical (·OH) generation section is turned off;

[0022] S32: O3 reacts with CPs: O3 is introduced into the third quartz tube with the gas flow and reacts with CPs coated on the third quartz tube.

[0023] Furthermore, it also includes:

[0024] S4: The gas after the reaction is introduced into the product absorption section, and the product is collected using an absorbent.

[0025] Furthermore, the concentration of O3 is controlled by adjusting the length x of the ultraviolet lamp irradiation. The relationship between the length x of the ultraviolet lamp irradiation and the generated O3 concentration y is as follows:

[0026] y = 27.561x - 80.511

[0027] Where x is in cm and y is in ppb.

[0028] Compared with existing technologies, the apparatus and method of this invention for investigating the CPs interfacial transformation reaction mediated by O3 and ·OH have achieved the following beneficial technical effects:

[0029] By constructing an interfacial reaction device for CPs mediated by O3 and ·OH, we can obtain the ambient concentration level of O3 and explore the transformation behavior of CPs at the real O3 concentration level. On the other hand, by separating the generation site of ·OH from the reaction site involved in the transformation of CPs, we can avoid the influence of ultraviolet light irradiation (254nm) on the direct photolysis of CPs and the further reaction of the generated products under ultraviolet light, thereby elucidating the interfacial transformation process and reaction mechanism of CPs mediated by the two active species. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic diagram of the structure of an apparatus for investigating the interfacial reactions of pollutants mediated by O3 and ·OH, provided in an embodiment of the present invention;

[0032] Figure 2 The degradation kinetics curves of SCCPs mediated by O3 and ·OH are provided in the embodiments of the present invention.

[0033] In the above figures, the meanings of the reference numerals are as follows: 1. Ozone generator; 11. First quartz tube; 12. 185nm ultraviolet lamp; 2. Hydroxyl radical reaction section; 21. Second quartz tube; 22. 254nm ultraviolet lamp; 3. Pollutant reactor; 31. Third quartz tube; 32. CPs coated on the third quartz tube; 4. Nitrogen input section; 5. Product absorption section; 51. Absorbents n-hexane and acetone; 52. Absorbent methanol; 6. O3 detector; 7. Humidity detection device; 8. Tail gas treatment section. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] like Figure 1 As shown in the embodiment of this application, an experimental apparatus for investigating ozone and hydroxyl radical-mediated CPs interfacial reactions includes:

[0036] Ozone (O3) generator 1, the ozone (O3) generator 1 includes a first quartz tube 11 and a 185nm ultraviolet lamp tube 12;

[0037] Hydroxyl radical (·OH) generating section 2, wherein the hydroxyl radical (·OH) generating section 2 includes a second quartz tube 21 and a 254nm ultraviolet lamp tube 22;

[0038] The reactor 3 of CPs includes a third quartz tube 31 and CPs 32 coated on the third quartz tube;

[0039] The first quartz tube 11, the second quartz tube 21, and the third quartz tube 31 are connected sequentially through pipelines.

[0040] Ozone (O3) generator 1 is an O3 generating device. The zero-level air introduced undergoes the following reaction under 185nm ultraviolet light irradiation:

[0041] 3O2 + hv (185nm) → 2O3

[0042] The relationship between the length x (cm) of the ultraviolet lamp irradiation and the generated O3 concentration y (ppb) is y = 27.561x - 80.511. The O3 concentration is controlled to maintain an environmental concentration level between 0 and 100 ppb by adjusting the length x.

[0043] In one embodiment of this application, a nitrogen input unit 4 is also included, which is connected to the second quartz tube 21 via a pipeline.

[0044] The high-purity nitrogen gas from the nitrogen input section 4, carrying water vapor, merges with the gas from the ozone (O3) generator 1 at the hydroxyl radical (·OH) generation section 2, where the following reaction occurs:

[0045] O3+hv(254nm)→O( 1 D)+O2;O( 1 D) + H2O → 2·OH, and the generated ·OH is carried by the gas flow to reactor 3 of CPs.

[0046] In this application, when the 254nm ultraviolet light of the hydroxyl radical (·OH) generation unit 2 is turned off, O3 passes through the hydroxyl radical (·OH) generation unit 2 and reacts with the CPs coated on the quartz tube in the reactor 3 of the CPs; when the 254nm ultraviolet light of the hydroxyl radical (·OH) generation unit 2 is turned on, the generated ·OH reacts with the CPs coated on the quartz tube in the reactor 3 of the CPs. Therefore, this application avoids the influence of ultraviolet light on the conversion of CPs by separating the ·OH generation device from the CPs reaction device.

[0047] In one embodiment of this application, a product absorption section 5 is also included, which is connected to the third quartz tube 31 via a pipeline and contains an absorbent.

[0048] Part of the parent compound and product are blown by the gas flow to the product absorption section 5 and absorbed by absorbent 51 (n-hexane / acetone v / v 1:1) and absorbent 52 (methanol), and then collected together. The parent compound and conversion product that are not blown away are eluted and collected using organic solvents (n-hexane, acetone and methanol). The collected parent compound and conversion product are concentrated by nitrogen blowing and then redissolved in n-hexane and methanol, respectively, and analyzed and determined by gas chromatography-high resolution mass spectrometry and liquid chromatography-high resolution mass spectrometry.

[0049] In one embodiment of this application, an O3 detector 6 and a humidity detection device 7 are also installed between the product absorption section and the third quartz tube to detect the concentration and humidity of O3 in the gas path.

[0050] In one embodiment of this application, an exhaust gas treatment unit 8 is also included.

[0051] The inventors of this application analyzed the collected results based on the experimental apparatus for reactive oxygen species-mediated SCCP interfacial conversion reactions, under the experimental conditions of 50 ppb O3 and 2.2 × 10⁻⁶ ppm. 9 molecules.cm -3Experimental data were obtained by mass spectrometry and plotted using the point-plotting method. Figure 2 .

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An experimental device for investigating ozone and hydroxyl radical mediated CPs interface reaction, characterized in that, comprising: an ozone (O3) generator comprising a first quartz tube and a 185 nm ultraviolet lamp tube; a hydroxyl radical (·OH) generating unit comprising a second quartz tube and a 254 nm ultraviolet lamp tube; a CPs reactor comprising a third quartz tube and CPs coated on the third quartz tube; the first quartz tube, the second quartz tube and the third quartz tube are sequentially connected by pipelines; further comprising a nitrogen gas input unit connected with the second quartz tube by a pipeline; further comprising a product absorption unit connected with the third quartz tube by a pipeline and having an absorbent placed inside.

2. The experimental device according to claim 1, characterized in that, further comprising an O3 detector and a humidity detection device installed between the product absorption unit and the third quartz tube.

3. The experimental device according to claim 2, characterized in that, the absorbent comprises n-hexane / acetone with a volume ratio of 1:1, and / or methanol.

4. An experimental method of the experimental device for investigating ozone and hydroxyl radical mediated CPs interface reaction according to claim 3, characterized in that, comprising the following steps: S1: low concentration ozone (O3) preparation: introducing zero-level air into the ozone (O3) generator to generate 0-100 ppb of O3 under 185 nm ultraviolet light irradiation; S21: hydroxyl radical (·OH) preparation: delivering the O3 prepared in step S1 to the second quartz tube, while inputting high-purity nitrogen gas carrying water vapor into the O3 through the nitrogen gas input unit, and irradiating with 254 nm ultraviolet light; S31: reaction of hydroxyl radical (·OH) with CPs: delivering the hydroxyl radical (·OH) prepared in step S2 into the third quartz tube with gas flow, and reacting with CPs coated on the third quartz tube.

5. An experimental method of the experimental device for investigating ozone and hydroxyl radical mediated CPs interface reaction according to claim 4, characterized in that, comprising the following steps: S1: low concentration ozone (O3) preparation: introducing zero-level air into the ozone (O3) generator to generate 0-100 ppb of O3 under 185 nm ultraviolet light irradiation; S22: O3 passing through the second quartz tube: delivering the O3 prepared in step S1 to the second quartz tube, while turning off the 254 nm ultraviolet light irradiation of the hydroxyl radical (·OH) generating unit; S32: O3 and CPs reaction: delivering O3 into the third quartz tube with gas flow, and reacting with CPs coated on the third quartz tube.

6. The experimental method according to claim 4 or 5, characterized in that, further comprising: S4: introducing the reacted gas into the product absorption unit to collect the product by using the absorbent.

7. The experimental method according to claim 4 or 5, characterized in that, The concentration of O3 is controlled by adjusting the length x of the UV lamp irradiation, and the relationship between the length x of the UV lamp irradiation and the generated O3 concentration y is as follows: y = 27.6x - 80.5 wherein the unit of x is cm, and the unit of y is ppb.

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