A system and method for detecting organic fluorides in water

Abstract

This application provides a system and method for detecting organofluorine compounds in water, belonging to the field of water pollutant detection technology. Based on the microcoulometric method for halogen content detection, this method utilizes modified activated carbon to adsorb organofluorine compounds in water through hydrophobic-hydrophobic interactions and electrostatic interactions, achieving a removal rate of up to 80%. Furthermore, the adsorption method is characterized by short adsorption time, low cost, high efficiency, and simple operation. In addition, the system has a simple and compact structure, integrating adsorption, elution, ignition, and titration into a single treatment device. Through multiple processes such as physical adsorption, oxidation, and reduction, it achieves comprehensive detection of total organic fluorine in water, showing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of water pollutant detection technology, and relates to a system and method for detecting organic fluoride compounds in water. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFAS) are a diverse group of synthetic chemicals with strong carbon-fluorine bonds. They also possess excellent properties such as strong resistance to degradation, water and oil repellency, thermal stability, and chemical stability, and are widely used in various industrial and consumer fields.

[0003] PFAS have long environmental half-lives, thus they gradually accumulate in biota, surface water, groundwater, soil, and atmospheric environments, causing harmful effects on humans and wildlife, including but not limited to cancer, autoimmune diseases, and high cholesterol. Currently, various types of PFAS have been detected in different water bodies in my country and other countries, and multiple types of perfluorinated compounds often coexist in the same water body.

[0004] Currently, the main methods for detecting organofluorine compounds in water include ion chromatography, spectrophotometry, atomic absorption spectrometry, inductively coupled plasma atomic absorption spectrometry, mass spectrometry, headspace gas chromatography, gas chromatography-mass spectrometry, high-performance liquid chromatography, and microcoulometric methods. However, the microcoulometric method suffers from limitations such as limited adsorption capacity and low recovery rate. Although existing technologies can detect the content of a single fluoride in water, they cannot comprehensively reflect the total amount of organofluorine compounds in water. Summary of the Invention

[0005] The purpose of this invention is to provide a system and method for detecting organic fluoride in water, so as to solve the problem that existing detection methods cannot comprehensively detect the content of organic fluoride in water.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, this application provides a method for detecting organofluorine compounds in water, the method comprising: Modified activated carbon is placed in an adsorption column. The water sample to be tested is acidified with dilute nitric acid and then passed into the adsorption column and through the modified activated carbon to obtain adsorbed activated carbon. The adsorbed activated carbon was eluted with sodium thiosulfate solution to obtain eluted activated carbon. The eluted activated carbon is fully combusted in an oxygen stream, and the generated hydrogen halide gas is passed into a microcoulomb cell to determine the halide ion content. The method for preparing the modified activated carbon includes: Cr(NO3)3·9H2O, H2BDC (Chinese name: terephthalic acid) and HF are dissolved in distilled water, stirred evenly, and then subjected to hydrothermal synthesis reaction at 180-220℃ for 12-20h to obtain a mixed reaction solution. Polyethyleneimine was dissolved in deionized water and stirred until dissolved. Then anhydrous ethanol was slowly added and stirred until homogeneous to obtain a polyethyleneimine precursor solution. Activated carbon was added to the polyethyleneimine precursor solution to obtain a modified activated carbon dispersion. The mixed reaction solution was mixed with the modified activated carbon dispersion, and after cooling, centrifugation, DMF washing, and drying, modified activated carbon was obtained.

[0007] Secondly, this application provides a system for detecting organofluorine compounds in water. The system includes: a gas pipeline, a mixing chamber, a combustion tube, a microcoulomb cell, and a microcoulomb titration cell connected in series. The mixing chamber is connected to an adsorption column through an inlet, and the adsorption column is filled with the modified activated carbon described in the first aspect.

[0008] The present invention has the following beneficial effects: (1) In this application, modified activated carbon MIL-101(Cr)@AC is prepared by combining activated carbon with metal-organic framework MOFs: MIL-101(Cr). The modified activated carbon MIL-101(Cr)@AC has the characteristics of small volume, large specific surface area, and the advantages of both AC and MIL-101(Cr). The removal rate of organic fluorides such as perfluorooctanoic acid is 80%, and the adsorption time is 2h.

[0009] (2) The adsorption principle of the modified activated carbon MIL-101(Cr)@AC in this application for organofluorine compounds is mainly based on hydrophobic-hydrophobic interaction and electrostatic interaction, both of which affect the adsorption of MIL-101(Cr)@AC.

[0010] (3) The modified activated carbon MIL-101 (Cr)@AC in this application is a regenerable activated carbon with a regeneration rate of 70%, which greatly reduces the loss of raw materials and lowers the testing cost.

[0011] (4) The detection method in this application improves the traditional single fluoride content detection. Based on the microcoulometric method for halogen content detection, it achieves the determination of the total fluoride content in the water sample. Moreover, the adsorption method is low in cost, high in efficiency, and simple in operation.

[0012] (5) In this application, the length of the inlet tube was increased on the basis of the original microcoulomb cell, which improved the dissolution efficiency of hydrogen halide gas and the effect of microcoulomb titration in the later stage.

[0013] (6) The system has a simple and compact structure and is a treatment device that integrates adsorption, elution, ignition and titration. Through physical adsorption, oxidation and reduction, it can achieve comprehensive detection of total organic fluoride in water and has broad application prospects. Attached Figure Description

[0014] Figure 1 A schematic diagram of the system for detecting organic fluorides in water provided in this application; Figure 2 This is a SEM image (scanning electron microscope) of the solid composite MIL-101 (Cr) prepared in Example 2 of this application. Figure 3 This is a SEM image of the activated carbon AC used in Example 2 of this application; Figure 4 This is a SEM image of the modified activated carbon MIL-101 (Cr)@AC prepared in Example 2 of this application; Symbolic representation: 1-Adsorption column, 2-Gas pipeline, 3-Inlet, 4-Combustion tube, 5-Combustion furnace, 6-Microcoulomb cell, 7-Control unit, 8-Stirrer, 9-Microcoulomb titration cell, 10-Mixing chamber, 11-Water sample, 12-Combustion chamber, 13-Vaporization chamber. Detailed Implementation

[0015] This application provides a method for detecting organofluorine compounds in water, the method comprising: S01: The modified activated carbon is placed in the adsorption column. The water sample to be tested is acidified with dilute nitric acid and then passed into the adsorption column and through the modified activated carbon to obtain the adsorbed activated carbon.

[0016] Measure 1.36 mL of nitric acid and dilute to 1000 mL with water to prepare a 0.02 mol / L dilute nitric acid solution. Add 3 mL of the dilute nitric acid solution to the water sample to be tested for acidification. Place the modified activated carbon in an adsorption column and pass the acidified water sample into the adsorption column so that the modified activated carbon in the adsorption column adsorbs the organic fluorides in the water sample, thus obtaining the adsorbed activated carbon.

[0017] In this application, the modified activated carbon is prepared by combining activated carbon with metal-organic frameworks (MOFs):MIL-101(Cr). Specifically, the preparation method of this modified activated carbon includes: S011: Dissolve 2-4g Cr(NO3)3·9H2O, 0.8-0.85g H2BDC, and 0.15mL HF in 70ml distilled water and stir magnetically until homogeneous to form a mixture. Transfer the mixture to a polytetrafluoroethylene autoclave and perform a hydrothermal synthesis reaction at 180-220℃ for 12-20h to obtain a mixed reaction solution.

[0018] S012: Dissolve 5-10g of polyethyleneimine (PEI) in 70mL of deionized water, stir magnetically until completely dissolved, slowly add 30mL of anhydrous ethanol, continue stirring until homogeneous, bring the volume to 100mL, store in the dark, and obtain the polyethyleneimine precursor solution.

[0019] S013: Mix the polyethyleneimine precursor solution with activated carbon at a volume-to-mass ratio of 4 mL: 5 mg to obtain a modified activated carbon dispersion.

[0020] S014: The mixed reaction solution was mixed with the modified activated carbon dispersion, cooled, centrifuged, and washed twice with DMF to obtain a green paste. The green paste was dried in an oven at 60°C to obtain the solid composite MIL-101 (Cr) @AC.

[0021] In this application, the modified activated carbon (MIL-101(Cr)@AC) combines the advantages of both AC (activated carbon) and MIL-101(Cr), and can adsorb organic fluorides such as perfluorooctane sulfonic acid (PFOS) in the water sample. The removal rate of PFOS and other organic fluorides is 80%, and the adsorption time is 2 hours. The adsorption principle of MIL-101(Cr)@AC is mainly based on hydrophobic-hydrophobic interactions and electrostatic interactions, both of which affect the adsorption of MIL-101(Cr)@AC. Furthermore, the modified activated carbon (MIL-101(Cr)@AC) in this application is regenerable activated carbon, with a regeneration efficiency of up to 70%.

[0022] SO2: The adsorbed activated carbon was eluted with 100 mL of 0.3 mol / L sodium thiosulfate solution to obtain eluted activated carbon. During the elution process, sodium thiosulfate can undergo a substitution reaction with fluoride ions, thereby eluting the fluorides adsorbed in the modified activated carbon into the solution.

[0023] S03: Place the eluted activated carbon in a combustion tube and adjust the heating temperature. Introduce an oxygen flow of 40-80 mL / min into the combustion tube to ensure complete combustion of the eluted activated carbon, thereby oxidizing the remaining substances on the activated carbon to form hydrogen halide gas. Pass the generated hydrogen halide gas into a microcoulometric cell, and then into a microcoulometric titration cell. Calculate the halide ion content through titration. The calculation formula is as follows: in, The concentration of AOX (Chinese name: adsorbable organic halogen) in the actual sample is expressed in μg / L. The measured value of organic halogens in the sample to be tested; The values ​​for organic halogen determinations are given using ultrapure water as a blank; M is the molar mass of chlorine, expressed as Cl, taken as 35.45 g / mol; V is the volume of the sample to be tested, in L; The concentration of AOX in the sample to be tested is expressed in μg / L. The blank AOX concentration is expressed in μg / L; F is the Faraday constant, i.e., 96484.56 C / mol.

[0024] This application provides a system for detecting organofluorine compounds in water. The system includes: a gas pipeline, a mixing chamber, a combustion tube, a microcoulometric cell, and a microcoulometric titration cell connected in series. The mixing chamber is connected to an adsorption column through a sample inlet, and the adsorption column is filled with modified activated carbon.

[0025] In this application, modified activated carbon is fixed inside an adsorption column using ceramic cotton. The adsorption column has an inner diameter of 4-5 mm and a length of 50-65 mm. The combustion tube contains a combustion chamber and a gasification chamber. The combustion chamber is connected to a mixing chamber, and the gasification chamber is connected to the microcoulometric titration cell. A combustion furnace is located outside the combustion tube, and a control unit is located below the combustion furnace. A stirrer is located at the bottom of the microcoulometric titration cell.

[0026] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0027] Example 1 This application provides a system for detecting organofluorine compounds in water. The system includes a gas pipeline 2, a mixing chamber 10, a combustion tube 4, a microcoulometric cell 6, and a microcoulometric titration cell 9 connected in series. The mixing chamber 10 is connected to an adsorption column 1 via a sample inlet 3. The adsorption column 1 is filled with modified activated carbon, as shown in the attached figure. Figure 1 As shown.

[0028] The system includes a gas pipe 2 for introducing oxygen into the system, with an inlet at one end. A mixing chamber 10 holds the eluting activated carbon, through which the oxygen introduced via the gas pipe 2 flows. The top of the mixing chamber 10 is connected to an adsorption column 1 filled with modified activated carbon via a sample inlet 3, allowing the modified activated carbon to enter the mixing chamber 10 after elution by water sample 11. A combustion tube 4 is used to burn the eluting activated carbon; the resulting hydrogen halide gas is introduced into a microcoulometric cell 6, and then into a microcoulometric titration cell 9 to determine the halide ion content.

[0029] In this embodiment, the modified activated carbon is wrapped with ceramic wool before being filled into the adsorption column 1. This ensures the uniformity of the packing material. Simultaneously, the physical isolation and fixation provided by the ceramic wool reduces particle movement and wear, dust pollution, and damage to the quartz tube. In this embodiment, the adsorption column 1 has an inner diameter of 4-5 mm and a length of 50-65 mm, and is filled with 50 mg of modified activated carbon.

[0030] Furthermore, a combustion furnace 5 is provided outside the combustion tube 4, and a control unit 7 is provided below the combustion tube 4. The control unit 7 controls the oxygen flow rate and combustion temperature, thereby providing heat to the combustion tube 4 through the combustion furnace 5. The combustion tube 4 has a combustion chamber 12 and a gasification chamber 13 inside. The combustion chamber 12 is connected to the mixing chamber 10, and the gasification chamber 13 is connected to the microcoulomb cell 6. The washed activated carbon is burned in the combustion chamber 12, and the hydrogen halide material produced after combustion forms gas in the gasification chamber 13, which is then introduced into the microcoulomb cell 6.

[0031] In addition, to ensure sufficient reaction of hydrogen halide gas in the microcoulometric titration cell 9, a stirrer 8 is provided at the bottom of the microcoulometric titration cell 9. In this embodiment, the connecting pipe between the vaporization chamber 13 and the microcoulometric cell 6 extends into the microcoulometric cell 6 for a length of 25-30 cm, in order to improve the dissolution efficiency of hydrogen halide gas and the effect of subsequent microcoulometric titration.

[0032] Example 2 This application provides a method for preparing modified activated carbon, the method comprising: S201: Dissolve 4g Cr(NO3)3·9H2O, 0.83g H2BDC and 0.15mL HF in 70mL distilled water and stir magnetically until homogeneous to form a mixture. Transfer the mixture to a polytetrafluoroethylene autoclave and perform a hydrothermal synthesis reaction at 200℃ for 15h to obtain a mixed reaction solution.

[0033] S202: Dissolve 8g of polyethyleneimine in 70mL of deionized water, stir magnetically until completely dissolved, slowly add 30mL of anhydrous ethanol, continue stirring until homogeneous, and bring the volume to 100mL. Store in the dark to obtain a polyethyleneimine precursor solution.

[0034] S203: Mix the polyethyleneimine precursor solution with activated carbon at a volume-to-mass ratio of 4 mL: 5 mg to obtain a modified activated carbon dispersion.

[0035] S204: The mixed reaction solution was mixed with the modified activated carbon dispersion, cooled, centrifuged, and washed twice with DMF to obtain a green paste. The green paste was dried in an oven at 60°C to obtain modified activated carbon MIL-101 (Cr) @AC.

[0036] Example 3 This application provides a method for preparing modified activated carbon, the method comprising: S301: Dissolve 2g Cr(NO3)3·9H2O, 0.8g H2BDC and 0.15mL HF in 70ml distilled water and stir magnetically until homogeneous to form a mixture. Transfer the mixture to a polytetrafluoroethylene autoclave and perform a hydrothermal synthesis reaction at 180℃ for 20h to obtain a mixed reaction solution.

[0037] S302: Dissolve 5g of polyethyleneimine in 70mL of deionized water, stir magnetically until completely dissolved, slowly add 30mL of anhydrous ethanol, continue stirring until homogeneous, and bring the volume to 100mL. Store in the dark to obtain a polyethyleneimine precursor solution.

[0038] S303: Mix the polyethyleneimine precursor solution with activated carbon at a volume-to-mass ratio of 4 mL: 5 mg to obtain a modified activated carbon dispersion.

[0039] S304: The mixed reaction solution was mixed with the modified activated carbon dispersion, cooled, centrifuged, and washed twice with DMF to obtain a green paste. The green paste was dried in an oven at 60°C to obtain modified activated carbon MIL-101 (Cr) @AC.

[0040] Example 4 This application provides a method for preparing modified activated carbon, the method comprising: S401: Dissolve 4g Cr(NO3)3·9H2O, 0.85g H2BDC and 0.15mL HF in 70mL distilled water and stir magnetically until homogeneous to form a mixture. Transfer the mixture to a polytetrafluoroethylene autoclave and perform a hydrothermal synthesis reaction at 220℃ for 12h to obtain a mixed reaction solution.

[0041] S402: Dissolve 10g of polyethyleneimine in 70mL of deionized water, stir magnetically until completely dissolved, slowly add 30mL of anhydrous ethanol, continue stirring until homogeneous, and bring the volume to 100mL. Store in the dark to obtain a polyethyleneimine precursor solution.

[0042] S403: Mix the polyethyleneimine precursor solution with activated carbon at a volume-to-mass ratio of 4 mL: 5 mg to obtain a modified activated carbon dispersion.

[0043] S404: The mixed reaction solution was mixed with the modified activated carbon dispersion, cooled, centrifuged, and washed twice with DMF to obtain a green paste. The green paste was dried in an oven at 60°C to obtain modified activated carbon MIL-101 (Cr) @AC.

[0044] Example 5 This application provides a method for detecting organofluorine compounds in water, the method comprising: S501: Measure 1.36 mL of nitric acid and dilute to 1000 mL with water to prepare a 0.02 mol / L dilute nitric acid solution. Add 3 mL of the dilute nitric acid solution to the water sample to be tested for acidification. Place the modified activated carbon prepared in Example 2 into an adsorption column, and pass the acidified water sample to be tested into the adsorption column so that the modified activated carbon in the adsorption column adsorbs the organic fluorides in the water sample to obtain the adsorbed activated carbon.

[0045] S502: The adsorbed activated carbon was eluted with 100 mL of sodium thiosulfate solution with a concentration of 0.3 mol / L to obtain eluted activated carbon.

[0046] S503: Place the eluted activated carbon in a combustion tube and adjust the heating temperature. Introduce an oxygen flow of 40 mL / min into the combustion tube to ensure complete combustion of the eluted activated carbon, thereby oxidizing the remaining substances on the activated carbon to form hydrogen halide gas. Pass the generated hydrogen halide gas into a microcoulometric cell, and then into a microcoulometric titration cell. Calculate the halide ion content through titration testing.

[0047] Example 6 This application provides a method for detecting organofluorine compounds in water, the method comprising: S601: Measure 1.36 mL of nitric acid and dilute to 1000 mL with water to prepare a 0.02 mol / L dilute nitric acid solution. Add 3 mL of the dilute nitric acid solution to the water sample to be tested for acidification. Place the modified activated carbon prepared in Example 3 into an adsorption column, and pass the acidified water sample to be tested into the adsorption column so that the modified activated carbon in the adsorption column adsorbs the organic fluorides in the water sample to obtain the adsorbed activated carbon.

[0048] S602: The adsorbed activated carbon was eluted with 100 mL of sodium thiosulfate solution with a concentration of 0.3 mol / L to obtain eluted activated carbon.

[0049] S603: Place the eluted activated carbon in a combustion tube and adjust the heating temperature. Introduce an oxygen flow of 60 mL / min into the combustion tube to ensure complete combustion of the eluted activated carbon, thereby oxidizing the remaining substances on the activated carbon to form hydrogen halide gas. Pass the generated hydrogen halide gas into a microcoulometric cell, and then into a microcoulometric titration cell. Calculate the halide ion content through titration testing.

[0050] Example 7 This application provides a method for detecting organofluorine compounds in water, the method comprising: S701: Measure 1.36 mL of nitric acid and dilute to 1000 mL with water to prepare a 0.02 mol / L dilute nitric acid solution. Add 3 mL of the dilute nitric acid solution to the water sample to be tested for acidification. Place the modified activated carbon prepared in Example 4 into an adsorption column, and pass the acidified water sample to be tested into the adsorption column so that the modified activated carbon in the adsorption column adsorbs the organic fluorides in the water sample to obtain the adsorbed activated carbon.

[0051] S702: The adsorbed activated carbon was eluted with 100 mL of sodium thiosulfate solution with a concentration of 0.3 mol / L to obtain eluted activated carbon.

[0052] S703: Place the eluted activated carbon in a combustion tube and adjust the heating temperature. Introduce an oxygen flow of 80 mL / min into the combustion tube to ensure complete combustion of the eluted activated carbon, thereby oxidizing the remaining substances on the activated carbon to form hydrogen halide gas. Pass the generated hydrogen halide gas into a microcoulometric cell, and then into a microcoulometric titration cell. Calculate the halide ion content through titration testing.

[0053] In this application embodiment, a solid composite MIL-101 (Cr) was also prepared. The solid composite was obtained by cooling and centrifuging the mixed reaction solution in Example 2, washing it twice with DMF, and drying it in an oven at 60°C.

[0054] In this embodiment, the solid composite MIL-101(Cr), activated carbon AC, and the modified activated carbon MIL-101(Cr)@AC prepared in Example 2 were examined by scanning electron microscopy, and the results were obtained. Figure 2 -Appendix Figure 4 .

[0055] From the appendix Figure 2 -Appendix Figure 4 As can be seen, the solid composite MIL-101(Cr) is a crystal with a uniform cubic structure and octahedral shape, and a smooth surface. Activated carbon AC exhibits an irregular porous structure with a relatively high surface area. The morphology of the modified activated carbon MIL-101(Cr)@AC is similar to that of the solid composite MIL-101(Cr), and the surface of the solid composite MIL-101(Cr) is covered with activated carbon AC, indicating that a chemical interaction has occurred between the solid composite MIL-101(Cr) and the activated carbon AC.

[0056] To verify the high accuracy of the method for detecting total organic fluoride in water provided in this application and the high fluoride recovery rate of modified activated carbon MIL-101 (Cr)@AC, 4-fluorobenzoic acid was selected as the organic fluoride and a 100 mg / L 4-fluorobenzoic acid solution was prepared for verification. The preparation process of the 100 mg / L 4-fluorobenzoic acid mother liquor included: dissolving 73.68 mg of 4-fluorobenzoic acid in a 100 mL volumetric flask, dissolving 10 mL of the mother liquor in a 100 mL volumetric flask, diluting tenfold to obtain a 100 mg / L 4-fluorobenzoic acid solution, and dividing the solution into 50 mL portions.

[0057] Two adsorption columns were respectively filled with modified activated carbon MIL-101(Cr)@AC and AC wrapped in ceramic wool. Following the method in Example 2, 50 mL portions of 4-fluorobenzoic acid solution were passed into the adsorption columns containing the modified activated carbon MIL-101(Cr)@AC and AC, respectively. The halide ion content was then measured, and the organofluorine content was calculated using the formula. Calculations showed that after using the adsorption columns filled with modified activated carbon MIL-101(Cr)@AC and AC, the organofluorine contents were 86 mg / L and 60 mg / L, respectively. This indicates that the method provided in this application can effectively test the organofluorine content in water, and the recovery rate of organofluorines can reach over 80%, ensuring the relative accuracy of the detection results.

[0058] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of detecting organofluorides in water, characterized in that, include: Modified activated carbon is placed in an adsorption column. The water sample to be tested is acidified with dilute nitric acid and then passed into the adsorption column and through the modified activated carbon to obtain adsorbed activated carbon. The adsorbed activated carbon was eluted with sodium thiosulfate solution to obtain eluted activated carbon. The eluted activated carbon is fully combusted in an oxygen stream, and the generated hydrogen halide gas is passed into a microcoulomb cell to determine the halide ion content. The method for preparing the modified activated carbon includes: Cr(NO3)3·9H2O, H2BDC and HF are dissolved in distilled water, stirred evenly, and then subjected to hydrothermal synthesis at 180-220℃ for 12-20h to obtain a mixed reaction solution. Polyethyleneimine was dissolved in deionized water and stirred until dissolved. Then anhydrous ethanol was slowly added and stirred until homogeneous to obtain a polyethyleneimine precursor solution. Activated carbon was added to the polyethyleneimine precursor solution to obtain a modified activated carbon dispersion. The mixed reaction solution was mixed with the modified activated carbon dispersion, and after cooling, centrifugation, DMF washing, and drying, modified activated carbon was obtained.

2. The method of detecting organofluorides in water according to claim 1, wherein, The volume-to-mass ratio of the polyethyleneimine precursor solution to the activated carbon is 4 mL: 5 mg.

3. The method for detecting organofluorine compounds in water according to claim 1, characterized in that, The amounts of Cr(NO3)3·9H2O, H2BDC, HF and activated carbon are 2-4g, 0.8-0.85g, 0.15ml and 40-50mg, respectively.

4. The method for detecting organofluorine compounds in water according to claim 1, characterized in that, The concentration of the sodium thiosulfate solution is 0.3 mol / L.

5. The method of claim 1, wherein the method is characterized by, The oxygen flow rate is 40-80 mL / min.

6. A system for detecting organofluorine compounds in water, characterized in that, include: The gas pipeline (2), mixing chamber (10), combustion tube (4), microcoulomb cell (6) and microcoulomb titration cell (9) are connected in series. The mixing chamber (10) is connected to the adsorption column (1) through the injection port (3). The adsorption column (1) is filled with the modified activated carbon as described in claim 1.

7. The system for detecting organofluorine compounds in water according to claim 6, characterized in that, The modified activated carbon is fixed inside the adsorption column (1) by ceramic cotton. The inner diameter of the adsorption column (1) is 4-5 mm and the length is 50-65 mm.

8. The system for detecting organofluorine compounds in water according to claim 6, characterized in that, The combustion tube (4) is provided with a combustion chamber (12) and a gasification chamber (13) inside. The combustion chamber (12) is connected to the mixing chamber (10), and the gasification chamber (13) is connected to the microcoulomb cell (6). The combustion furnace (5) is provided outside the combustion tube (4), and a control unit (7) is provided below the combustion furnace (5).

9. The system for detecting organofluorine compounds in water according to claim 6, characterized in that, The bottom of the microcoulometric titration cell (9) is equipped with a stirrer (8).

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