An automated water quality volatile phenol analysis system

Abstract

This invention relates to the field of detection technology and discloses an automated water quality volatile phenol analysis system. The automated water quality volatile phenol analysis system provided by this invention uses a pneumatic push-in module to feed a mixture of sample and auxiliary distillation reagent into the distillation module at a stable flow rate for distillation separation and volatilization. The stable flow rate of the mixture into the distiller ensures more uniform and stable heating during distillation, allowing all volatile phenols in the water to be distilled out completely without residue. Simultaneously, the addition of auxiliary distillation reagent enriches and separates volatile phenols, making them easier to distill out and detect. This improves the detection sensitivity of volatile phenols in water with low concentrations of volatile phenols.

Description

Technical Field

[0001] This invention relates to the field of detection technology, and in particular to an automated system for analyzing volatile phenols in water. Background Technology

[0002] The main sources of phenol pollution include industrial wastewater from coal gas washing, coking, synthetic ammonia, papermaking, wood preservation, and the chemical industry. Phenolics are protoplasmic poisons and are highly toxic substances. Ingestion of a certain amount can cause acute poisoning symptoms. Long-term consumption of water contaminated with phenol can cause headaches, rashes, itching, anemia, and various neurological symptoms. When the phenol content in water is 0.1–0.2 mg / L, fish will have an off-flavor; at concentrations greater than 5 mg / L, fish will die from poisoning. Wastewater with high phenol concentrations should not be used for farmland irrigation, as it can cause crops to wither or suffer reduced yields.

[0003] Phenolic compounds are monocyclic, dicyclic, or polycyclic aromatic hydrocarbons with single, dicyclic, or polycyclic hydroxyl groups. Monocyclic phenols are more toxic than polycyclic phenols and can volatilize with water vapor, separating them from other phenolic compounds; therefore, they are commonly referred to as volatile phenols. Environmental pollution, especially water pollution, is a major global concern and a problem that urgently needs to be addressed. Volatile phenols are a key indicator of water pollution and one of the main indicators for assessing the degree of water pollution. Therefore, monitoring the content of volatile phenols in water bodies is a mandatory task for water environment monitoring centers.

[0004] my country's "Standards for Drinking Water Quality" stipulates that the content of volatile phenols (calculated as phenol) in drinking water shall not exceed 0.002 mg / L. There are many methods for detecting volatile phenols, generally including spectrophotometry, flow injection analysis (FIA), bromination volumetric method, and ion chromatography. The 4-aminoantipyrine spectrophotometric method is currently the most commonly used method for detecting volatile phenol content. While other methods have certain advantages, they are more expensive and not widely adopted. The 4-aminoantipyrine spectrophotometric method (HJ503-2009) is also the national standard method for detecting volatile phenols and is widely used.

[0005] The flow injection-4-aminoantipyrine spectrophotometric method (HJ825-2017) for the determination of volatile phenols in water is a commonly used classical method. This method is based on the internationally accepted standard method of 4-aminoantipyrine spectrophotometry and combines the advantages of non-steady-state quantitative analysis of the flow injection method. It has the advantages of high accuracy, fast analysis speed, simple operation, small sample and reagent consumption, low toxicity to laboratory personnel, and low risk of secondary pollution to the environment.

[0006] However, when using the flow injection-4-aminoantipyrine spectrophotometric method (HJ825-2017) to detect volatile phenols in water, the signal value (peak area) of the sample entering the flow detection cell is very low. This makes it difficult to test low-concentration samples. The low signal value of low-concentration samples can easily lead to unstable baselines, resulting in the standard curve linearity failing to reach above 0.999. Furthermore, it can cause the peak area of ​​the low-point sample on the standard curve to be indistinguishable from that of the blank sample, thus leading to deviations in the detection data.

[0007] Existing technologies primarily address the accuracy issues in testing low-concentration samples by including: (1) Increase the sample light front-end acquisition gain or simultaneously amplify the output magnification of the sample light and the reference light to improve the sample detection signal value (peak area). However, this method also amplifies the baseline fluctuations and does not significantly improve the linearity of the standard curve, resulting in the continued problem of poor accuracy of sample detection values.

[0008] (2) Increasing the sample loop length can improve the detection signal value (peak area) by increasing the injection volume. However, increasing the injection volume firstly increases the consumption of sample and reagents, which makes it difficult to repeat the test of the same sample. Secondly, based on the principle of flow injection method, increasing the injection volume leads to an increase in signal value (peak area), which also leads to a widening of the sample peak width, a smoothing of the peak tip, the appearance of flat-topped peaks and severe peak tailing, etc. As a result, there is a difference in peak width between high-concentration samples and low-concentration samples, which in turn affects the accuracy of sample testing.

[0009] Therefore, existing volatile phenol analyzers have not solved the problem of accuracy in detecting low concentrations of volatile phenols using the flow injection-4-aminoantipyrine spectrophotometric method. Summary of the Invention

[0010] To address the issue of accuracy in detecting low concentrations of volatile phenols in water, this invention provides an automated water volatile phenol analysis system.

[0011] The specific technical solution of this invention is as follows: This invention provides an automated water quality volatile phenol analysis system, comprising a first mixing module, a distillation module, a gas-liquid separation module, a condensation module, and a content detection module connected in sequence, and further comprising a pneumatic push module and an auxiliary detection module. The pneumatic push module is connected to the inlet of the distillation module, and the auxiliary detection module is connected to the content detection module. The first mixing module is used to prepare a mixture of sample and auxiliary distillation reagent; A pneumatic push-in module is used to feed the sample and auxiliary distillation reagent mixture into the inlet of the distillation module at a stable flow rate. The distillation module is used to distill the mixture of sample and auxiliary distillation reagents to form a stable gas flow of volatile phenols. A gas-liquid separation module is used to dry the volatile phenol gas stream from the distillation module to obtain gaseous volatile phenols; A condensation module is used to condense gaseous volatile phenols from the gas-liquid separation module to obtain liquid volatile phenols; The content detection module is used to detect the liquid volatile phenols from the condensation module to obtain the content of liquid volatile phenols in the sample; An auxiliary detection module is used to provide an auxiliary detection reagent that can assist in the content detection of liquid volatile phenols in the detection module.

[0012] As a preferred embodiment of the above-mentioned technical solution of the present invention, the auxiliary detection agent includes a buffer solution and a colorimetric reagent. The buffer solution is a potassium ferricyanide buffer solution, and the colorimetric reagent is a 4-aminoantipyrine solution.

[0013] As a preferred embodiment of the above technical solution of the present invention, the content detection module includes a colorimetric reaction unit and a detection unit; A colorimetric reaction unit is used to mix the liquid volatile phenols and auxiliary detection reagents to obtain the solution to be tested; The detection unit is used to detect the solution to be tested in order to obtain the content of liquid volatile phenols in the sample.

[0014] As a preferred embodiment of the above technical solution of the present invention, the detection unit is used to detect the optical signal of the solution to be tested, and to obtain the content of liquid volatile phenols in the sample based on the optical signal detection result.

[0015] As a preferred embodiment of the above-mentioned technical solution of the present invention, the auxiliary distillation reagent is a mixed solution of H3PO4, NaCl and MgSO4.

[0016] As a preferred embodiment of the above-mentioned technical solution of the present invention, the pneumatic push-in module includes an air pump and a gas flow meter connected in sequence, and the gas flow meter is also connected to the distillation module.

[0017] Further optimization involves installing a gas storage tank on the connecting pipeline between the air pump and the gas flow meter.

[0018] As a preferred embodiment of the above technical solution of the present invention, a degassing device is provided on the connecting pipeline between the condensation module and the content detection module.

[0019] More preferably, the condensation module includes a water storage tank, a water pump, a refrigeration component, a liquid flow meter, a condensation chamber, and a coiled condenser tube installed in the condensation chamber; The inlet of the swirling condenser is connected to the gas-liquid separation module, and the outlet of the swirling condenser is connected to the degassing device. The outlet of the condensing chamber is connected to the inlet of the water storage tank, the outlet of the water storage tank is connected to the inlet of the water pump, the outlet of the water pump is connected to the inlet of the refrigeration component, the outlet of the refrigeration component is connected to the inlet of the liquid flow meter, and the outlet of the cold liquid flow meter is connected to the inlet of the condensing chamber.

[0020] As a preferred embodiment of the above technical solution of the present invention, the distillation module includes a heating tank and a distiller loaded in the heating tank. The distiller has a spiral pipe structure from bottom to top. The inlet of the distiller is at the bottom and is connected to the pneumatic push-in module and the first mixing module, respectively. The outlet of the distiller is at the top and is connected to the gas-liquid separation module.

[0021] The spiral pipe structure from bottom to top should be understood as the pipe structure being perpendicular to the horizontal plane. Therefore, the phrases "the inlet of the distillation apparatus is at the bottom" and "the outlet of the distillation apparatus is at the top" allow the substance entering the distillation apparatus to enter from the bottom and exit from the top.

[0022] Compared with the prior art, the present invention has the following technical effects: To improve the peak area signal value of low-concentration volatile phenol samples, existing technologies employ methods such as increasing the sample optical front-end acquisition gain or simultaneously amplifying the output magnification of both sample and reference light. However, this approach suffers from amplified baseline fluctuations, hindering accuracy improvement in low-concentration volatile phenol detection. Another existing method, increasing the sample loop length, leads to sample consumption issues and results in wider peaks, flat-topped peaks, and severe peak tailing. The automated volatile phenol analysis system for water quality provided by this invention utilizes a pneumatically pressurized push-in module to deliver a mixture of sample and auxiliary distillation reagents at a stable flow rate into the distillation module for distillation and separation. The stable flow rate of the mixture into the distiller ensures more uniform and stable heating during distillation, resulting in complete distillation of volatile phenols from the water without residue. Simultaneously, the addition of auxiliary distillation reagents enriches and separates volatile phenols, making them easier to distill and detect. This improves the detection sensitivity of volatile phenols in low-concentration water samples. This system avoids the drawbacks of methods that require increasing the peak area signal value of low-concentration volatile phenol samples by adjusting the sample light front-end acquisition gain, simultaneously amplifying the output magnification of the sample light and the reference light, or increasing the sample ring length.

[0023] Furthermore, through experiments, this invention determined the substances and their proportions that have the best effect on the enrichment and distillation separation of volatile phenols. An auxiliary distillation reagent for the distillation separation of volatile phenols in water is provided, which is a mixed solution of H3PO4, NaCl, and MgSO4. Under conditions where solubility allows, NaCl and MgSO4 are simultaneously added to phosphoric acid as auxiliary distillation reagents. The higher the concentration of NaCl and MgSO4 added, the better the effect on improving the distillation efficiency of volatile phenols. The addition of this auxiliary distillation reagent can enrich and separate volatile phenols from water with low concentrations of volatile phenols. This is particularly important for the detection of volatile phenols in water with low concentrations of volatile phenols. Based on this, the peak area of ​​the volatile phenol signal in water with low concentrations of volatile phenols is increased, thereby improving the accuracy of low-concentration volatile phenol detection. Attached Figure Description

[0024] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a structural block diagram of an automated water quality volatile phenol analysis system according to the present invention; Figure 2 This is a schematic diagram of an automated water quality volatile phenol analysis system according to the present invention.

[0026] The attached figures are labeled as follows: 1. Air pump, 2. Gas storage tank, 3. Gas flow meter, 4. Heating tank, 5. Distillation apparatus, 6. Gas-liquid separation module, 7. Coiled condenser, 8. Condensation chamber, 9. Water storage tank, 10. Water pump, 11. Refrigeration component, 12. Liquid flow meter, 13. First mixing module, 14. Auxiliary detection module, 15. Content detection module, 1501. Colorimetric reaction unit, 1502. Detection unit, 16. Degassing device. Detailed Implementation

[0027] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0028] In the following description, several embodiments of this application are provided. Different embodiments can be substituted or combined. Therefore, this application can also be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more other possible combinations of A, B, C, and D, even if such embodiments are not explicitly described in the following text.

[0029] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this application. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0030] Example 1 like Figures 1-2 As shown, this embodiment provides an automated water quality volatile phenol analysis system: like Figure 1 As shown, the system includes a first mixing module, a distillation module, a gas-liquid separation module, a condensation module, and a content detection module connected in sequence. It also includes a pneumatic push-in module and an auxiliary detection module. The pneumatic push-in module is connected to the inlet of the distillation module, and the auxiliary detection module is connected to the content detection module. (Reference) Figure 2 ,in: First mixing module 13: used to prepare a mixture of sample and auxiliary distillation reagent.

[0031] Pneumatic push-in module: used to feed the sample and auxiliary distillation reagent mixture into the distillation module at a stable flow rate at the inlet of the distillation module.

[0032] Distillation module: Used for distilling the mixture of sample and auxiliary distillation reagents to form a stable gas flow of volatile phenols; Gas-liquid separation module 6: Used to dry the volatile phenol gas stream from the distillation module to obtain gaseous volatile phenol; Condensation module: used to condense gaseous volatile phenols from gas-liquid separation module 6 to obtain liquid volatile phenols; Content detection module 15: Used to detect liquid volatile phenols from the condensation module to obtain the content of liquid volatile phenols in the sample.

[0033] Auxiliary detection module 14: Used to provide an auxiliary detection reagent to assist in the content detection of liquid volatile phenols in the detection module.

[0034] In a preferred embodiment, the auxiliary detection agent includes a buffer solution and a colorimetric reagent. The buffer solution is a potassium ferricyanide buffer solution, and the colorimetric reagent is a 4-aminoantipyrine solution. Phenolic compounds react with 4-aminoantipyrine to form an orange-red antipyrine dye, and the absorbance is measured at a wavelength of 510 nm to determine the content of volatile phenols. The purpose of adding the buffer solution is to adjust the pH of the solution to a weakly alkaline medium of pH 10.0 ± 0.2, ensuring that under appropriate alkaline conditions, a complexation reaction can occur between the volatile phenols and 4-aminoantipyrine, forming a stable complex.

[0035] As a preferred embodiment, the content detection module 15 includes a colorimetric reaction unit 1501 and a detection unit 1502; The colorimetric reaction unit 1501 is used to mix the liquid volatile phenol and the auxiliary detection agent to carry out a colorimetric reaction to obtain the solution to be tested; The detection unit 1502 is used to detect the solution to be tested in order to obtain the content of liquid volatile phenols in the sample.

[0036] In a preferred embodiment, the detection unit 1502 is used to detect the optical signal of the solution to be tested, and to obtain the content of liquid volatile phenols in the sample based on the optical signal detection results.

[0037] As a preferred embodiment, the auxiliary distillation reagent is a mixed solution of H3PO4, NaCl, and MgSO4, wherein the volume fraction of H3PO4 is 10%, the concentration of NaCl is 155 g / L, and the concentration of MgSO4 is 50 g / L.

[0038] The addition of this auxiliary distillation reagent allows for the enrichment and separation of volatile phenols in water samples with low concentrations of volatile phenols. This is particularly important for the detection of volatile phenols in water samples with low concentrations of volatile phenols, thereby improving the detection sensitivity. By ensuring the complete separation and detection of small amounts of volatile phenols in the water, there is no need to increase the peak area signal value of low-concentration volatile phenol samples by increasing the sample optical front-end acquisition gain, simultaneously amplifying the output magnification of the sample light and reference light, or increasing the sample ring length. This avoids the drawbacks of the aforementioned methods. Increasing the sample optical front-end acquisition gain or simultaneously amplifying the output magnification of the sample light and reference light can amplify baseline fluctuations. Increasing the sample ring length can lead to sample consumption issues and result in wider peak widths, flat-topped peaks, and severe peak tailing.

[0039] In a preferred embodiment, the pneumatic push-in module includes an air pump 1 and a gas flow meter 3 connected in sequence, and the gas flow meter 3 is also connected to the distillation module.

[0040] By connecting the gas pump 1 and the gas flow meter 3 in sequence, the sample and auxiliary distillation reagent mixture can be sent into the distillation module at a stable flow rate at the inlet of the distillation module for distillation separation and volatilization. The mixture enters the distiller 5 at a stable flow rate, which can make the distillation heating more uniform and stable, so that the small amount of volatile phenols in the water can be completely distilled out without residue, thereby improving the peak area signal value of the detection.

[0041] Furthermore, this system can improve the analysis rate and thus increase work efficiency by adjusting the gas flow rate through a pneumatic push-in module. Using gas to push the sample and auxiliary distillation reagent mixture into the distillation module allows for a more stable flow rate, ensuring stable delivery of the mixture even at high gas flow rates, thereby improving distillation efficiency.

[0042] Further optimization involves installing a gas storage tank 2 on the connecting pipeline between the air pump 1 and the gas flow meter 3.

[0043] Adding a gas storage tank 2 between the gas pump 1 and the gas flow meter 3 for buffering can reduce pulsation and ensure stable gas flow.

[0044] As a preferred embodiment of the above technical solution, a degassing device is provided on the connecting pipeline between the condensation module and the content detection module 15.

[0045] A degassing device 16 is installed on the connecting pipeline between the condensation module and the content detection module 15. This device regulates the pressure balance of the flow path and maintains flow path stability. Simultaneously, this embodiment employs a pneumatic push-in module, using gas to feed the sample and auxiliary distillation reagent mixture into the distillation module at a stable flow rate at the inlet for distillation, achieving complete separation of small amounts of volatile phenols from the water. During this process, it is inevitable that gas introduced by the pneumatic push-in module will mix into the gaseous volatile phenols obtained after distillation. Therefore, a degassing device is necessary on the connecting pipeline between the condensation module and the content detection module 15 to remove this gas and avoid affecting the accuracy of the detection results.

[0046] More preferably, the condensation module includes a water storage tank 9, a water pump 10, a refrigeration component 11, a liquid flow meter 12, a condensation chamber 8, and a coiled condenser tube 7 installed in the condensation chamber 8; The inlet of the spiral condenser tube 7 is connected to the gas-liquid separation module 6, and the outlet of the spiral condenser tube 7 is connected to the degassing device. The outlet of the condensation chamber 8 is connected to the inlet of the water storage tank 9, the outlet of the water storage tank 9 is connected to the inlet of the water pump 10, the outlet of the water pump 10 is connected to the inlet of the refrigeration component 11, the outlet of the refrigeration component 11 is connected to the inlet of the liquid flow meter 12, and the outlet of the cold liquid flow meter 12 is connected to the inlet of the condensation chamber 8. This structure enables the recycling of the refrigerant.

[0047] Preferably, the outlet of the condensing chamber 8 is located at its top and the inlet is located at its bottom, which results in better condensation.

[0048] In a preferred embodiment, the distillation module includes a heating tank 4 and a distiller 5 loaded in the heating tank 4. The distiller 5 has a spiral pipe structure from bottom to top. The inlet of the distiller 5 is at the bottom and is connected to the pneumatic push-in module and the first mixing module 13, respectively. The outlet of the distiller 5 is at the top and is connected to the gas-liquid separation module 6.

[0049] The heating tank contains a heat transfer medium, which can be heated by a heating rod installed inside the tank. The heat transfer medium keeps the distiller at 165℃±2℃, allowing volatile phenols to be released through online distillation.

[0050] The spiral pipe structure from bottom to top should be understood as the pipe structure being perpendicular to the horizontal plane. Therefore, the phrases "the inlet of the distillation apparatus is at the bottom" and "the outlet of the distillation apparatus is at the top" allow the substance entering the distillation apparatus to enter from the bottom and exit from the top.

[0051] The distiller is designed with a spiral pipe structure from bottom to top. Due to gravity, the sample inside the spiraling pipe stays in the pipe for a longer time, and the liquid flowing through it is heated more evenly, resulting in better distillation and separation.

[0052] The technical effects achieved by this embodiment include: (1) The automated water quality volatile phenol analysis system provided in this embodiment uses a pneumatic push-in module to feed the sample and auxiliary distillation reagent mixture into the distillation module at a stable flow rate for distillation separation and volatilization. The stable flow rate of the mixture into the distiller ensures more uniform and stable heating during distillation, allowing all volatile phenols in the water to be distilled out without residue. Simultaneously, the addition of auxiliary distillation reagents enriches and separates volatile phenols, making them easier to distill out and detect. This improves the detection sensitivity of volatile phenols in water with low concentrations. This system avoids the drawbacks of methods that require increasing the sample light front-end acquisition gain, simultaneously amplifying the output magnification of the sample light and reference light, or increasing the sample ring length to improve the peak area signal value of low-concentration volatile phenol samples.

[0053] (2) Further, in this embodiment, a degassing device is installed on the connecting pipeline between the condensation module and the content detection module, which has the effect of regulating the pressure balance of the flow path and maintaining the stability of the flow path. Simultaneously, this embodiment uses a pneumatic push-in module, which uses gas to send the sample and auxiliary distillation reagent mixture into the distillation module at a stable flow rate at the inlet of the distillation module for distillation, thereby achieving complete separation of the small amount of volatile phenols in the water. In this process, it is inevitable that the gaseous volatile phenols obtained after distillation will be mixed with gas introduced by the pneumatic push-in module. Therefore, a degassing device needs to be installed on the connecting pipeline between the condensation module and the content detection module to remove this gas and avoid affecting the accuracy of the detection results.

[0054] Example 2 Based on the automated water quality volatile phenol analysis system provided in Example 1, this example uses standard samples of volatile phenols in water with concentrations of 0.000, 0.002, 0.005, 0.010, 0.020, 0.050, and 0.100 mg / L (denoted as ① to ⑦), and optimizes the complexes and ratios of the auxiliary distillation reagent. The volume of the standard sample is 7 mL, and the volume of the auxiliary distillation reagent is 5 mL.

[0055] The test method for volatile phenols is as follows: A standard curve is plotted based on the peak area of ​​the absorbance of the measured standard solution and the concentration of the standard solution. The volatile phenols in the sample are then calculated from the peak area of ​​the sample absorbance on the standard curve. The absorbance is defined as A = lgI0 = εbc, where A is the absorbance, I0 is the incident light intensity, I is the emitted light intensity, and ε is the molar absorptivity (cm-1). -1 ·mol -1 b is the liquid layer thickness (cm); c is the solution concentration (mol·L). -1 ).

[0056] In this embodiment, the concentration of 4-aminoantipyrine solution was 0.64 g / L, the concentration of potassium ferricyanide in potassium ferricyanide buffer was 2.0 g / L, the carrier was freshly prepared phenol-free water, and the reagent preparation was in accordance with HJ825-2017 Determination of Volatile Phenols in Water - Flow Injection-4-Aminoantipyrine Spectrophotometric Method.

[0057] 1. Using reagents A through E as auxiliary distillation reagents, the above standard samples were analyzed, and the peak area results are shown in Table 1. Here, C0 refers to the test of the blank standard sample (i.e., the standard sample with a concentration of 0) immediately after the test of sample ⑦. Reagents A through E are respectively: A: 10% phosphoric acid solution, the volume percentage of phosphoric acid is 10%; B: A mixed solution of phosphoric acid and KCl, with phosphoric acid at a volume percentage of 10% and KCl at a concentration of 200 g / L; C: A mixed solution of phosphoric acid and CaCl2, with phosphoric acid at a volume percentage of 10% and CaCl2 at a concentration of 200 g / L; D: A mixed solution of phosphoric acid and NaCl, with phosphoric acid at a volume percentage of 10% and NaCl at a concentration of 200 g / L; E: A mixed solution of phosphoric acid and MgCl2, with phosphoric acid accounting for 10% by volume and MgCl2 having a concentration of 200 g / L.

[0058] Table 1 As shown in Table 1, when reagents B through E were used as auxiliary distillation reagents, compared to when reagent A was used alone, the peak area growth rates were as follows: For reagent B, the peak area growth rate for low-concentration standard samples (0.002-0.01 mg / L) was 28.8-31.8%, and for high-concentration standard samples (0.02-0.1 mg / L) it was 33.4-37.6%; for reagent C, the peak area growth rate for low-concentration standard samples (0.002-0.01 mg / L) was 45.1-50.1%, and for high-concentration standard samples (0.02-0.1 mg / L) it was 33.4-37.6%. The peak area growth rate of reagent C for low-concentration standard samples (0.002-0.01 mg / L) was 40.0-43.8%; the peak area growth rate of reagent D for low-concentration standard samples (0.002-0.01 mg / L) was 31.3-40.9%, and the peak area growth rate of reagent E for high-concentration standard samples (0.02-0.1 mg / L) was 41.8-47.1%; the peak area growth rate of reagent E for low-concentration standard samples (0.002-0.01 mg / L) was 33.6-46.2%, and the peak area growth rate of reagent E for high-concentration standard samples (0.02-0.1 mg / L) was 43.1-46.1%. Repeated tests confirmed that the addition of reagent C caused the back-calculation of blank sample tests to be higher after testing high-concentration samples; the peak area growth of reagents D and E was not significantly different, and the back-calculation concentration of blank samples was normal after testing high-concentration samples, but the MgCl2 in reagent E reacted violently when dissolved in water and produced black turbidity, requiring filtration before use. In conclusion, a mixed solution of phosphoric acid and NaCl was chosen as the auxiliary distillation reagent.

[0059] 2. Using the same method as 1, we investigated the effects of adding NaCl, KCl+NaCl combination, CaCl2+NaCl combination, MgSO4+NaCl combination, NaHCO3+NaCl combination, and NaCl+Brij35 activator combination to a 10% phosphoric acid solution for distillation.

[0060] The above standard samples were analyzed using reagents A, F, G, G1, H, I, and J as auxiliary distillation reagents, respectively. The peak area results are shown in Tables 2-6. DL represents the standard deviation of seven repeated tests of a 0.002 mg / L standard sample. Standard HJ 503-2009 specifies a detection limit of 0.0003 mg / L for the determination of surface water, groundwater, and drinking water using extraction spectrophotometry. Reagents F through J are respectively: F: A mixed solution of phosphoric acid, NaCl, and KCl, with phosphoric acid at a volume percentage of 10%, NaCl at a concentration of 100 g / L, and KCl at a concentration of 100 g / L. G: A mixed solution of phosphoric acid, NaCl, and MgSO4, wherein the volume percentage of phosphoric acid is 10%, the concentration of NaCl is 93 g / L, and the concentration of MgSO4 is 30 g / L. G1: A mixed solution of phosphoric acid, NaCl, and MgSO4, with phosphoric acid at a volume percentage of 10%, NaCl at a concentration of 155 g / L, and MgSO4 at a concentration of 50 g / L. H: A mixed solution of phosphoric acid, NaCl, and CaCl2, with a volume percentage of 10% for phosphoric acid, a NaCl concentration of 77.5 g / L, and a CaCl2 concentration of 77.5 g / L. I: A mixed solution of phosphoric acid, NaCl, and NaHCO3, wherein the volume percentage of phosphoric acid is 10%, the concentration of NaCl is 175 g / L, and the concentration of NaHCO3 is 2.5 g / L; J: A mixed solution of phosphoric acid, NaCl, and Brij35, wherein the volume percentage of phosphoric acid is 10%, the concentration of NaCl is 150 g / L, and the concentration of Brij35 is 1 g / L.

[0061] Table 2 Table 2 shows that, when reagent F (a mixed solution of phosphoric acid, NaCl, and KCl) was used as an auxiliary distillation reagent, the peak area growth rate was 29.6-33.9% for low-concentration standard samples (0.002-0.01 mg / L) and 26.2-34.2% for high-concentration standard samples (0.02-0.1 mg / L) compared to reagent A alone. This is lower than the peak area growth rate of reagent D (37.5-39.2%). Therefore, the mixed solution of phosphoric acid, NaCl, and KCl is not effective as an auxiliary distillation reagent.

[0062] Table 3 As shown in Table 3, when reagent G, i.e., a mixed solution of phosphoric acid, NaCl, and MgSO4, is used as an auxiliary distillation reagent, the peak area growth rate is 14.2-19.7% for low-concentration standard samples (0.002-0.01 mg / L) and 16.6-22.3% for high-concentration standard samples (0.02-0.1 mg / L), compared to reagent A alone. When a mixed solution of NaCl with a concentration of 93 g / L and a volume percentage of phosphoric acid of 10% is used as an auxiliary distillation reagent, the peak area growth rate is 12.0-18.4% for low-concentration standard samples (0.002-0.01 mg / L) and 13.2-19.4% for high-concentration standard samples (0.02-0.1 mg / L). Therefore, the mixed solution of phosphoric acid, NaCl, and MgSO4 is more effective as an auxiliary distillation reagent.

[0063] Table 4 As shown in Table 4, reagent G1, a mixed solution of phosphoric acid, NaCl, and MgSO4, compared to reagent A alone as an auxiliary distillation reagent, showed a peak area increase of 45.8-50.4% for low-concentration standard samples (0.002-0.01 mg / L) and 36.0-38.2% for high-concentration standard samples (0.02-0.1 mg / L); reagent H, a mixed solution of phosphoric acid, NaCl, and CaCl2, compared to reagent A alone as an auxiliary distillation reagent, showed a peak area increase of 36.0-38.2% for low-concentration standard samples (0.002-0.01 mg / L). The peak area growth rate for 0.02-0.01 mg / L samples was 32.3-36.2%, while the peak area growth rate for high-concentration standard samples (0.02-0.1 mg / L) was 33.4-35.3%. Compared with reagent H, reagent G1 showed a slightly higher peak area growth rate. However, reagent H resulted in more crystallization in the pipeline after testing, and CaCl2 caused the distillation reagent to become viscous, which was not conducive to long-term testing. Furthermore, reagent H increased the peak area of ​​blank samples. In summary, the mixed solution of phosphoric acid, NaCl, and MgSO4 was the best auxiliary distillation reagent.

[0064] Tables 3 and 4 show that reagent G and reagent G1 differ only in the concentrations of NaCl and MgSO4, but reagent G1 exhibits a greater peak area growth rate. This indicates that in a mixed solution of phosphoric acid, NaCl, and MgSO4, a concentration of 10% phosphoric acid (volume percentage), 155 g / L NaCl, and 50 g / L MgSO4 provides the best auxiliary distillation effect. Furthermore, under solubility-allowed conditions, when NaCl and MgSO4 are added simultaneously to phosphoric acid, higher concentrations of NaCl and MgSO4 result in a greater improvement in the distillation efficiency of volatile phenols.

[0065] Table 5 Table 5 shows that, when reagent I (a mixed solution of phosphoric acid, NaCl, and NaHCO3) was used as the auxiliary distillation reagent, compared to using reagent A alone, the peak area increase was 36.4-40.6% for low-concentration standard samples (0.002-0.01 mg / L) and 34.9-36.3% for high-concentration standard samples (0.02-0.1 mg / L). A mixed solution of NaCl (175 g / L) and phosphoric acid (10% by volume) was also used as the auxiliary distillation reagent. The peak area growth rate of the reagent was 34.6-39.6% for low-concentration standard samples (0.002-0.01 mg / L) and 35.0-37.4% for high-concentration standard samples (0.02-0.1 mg / L). The peak area growth rates of the two were not significantly different. However, phosphoric acid reacts with sodium bicarbonate, introducing interference. In multiple tests, the peak area of ​​blank samples was increased. Therefore, the mixed solution of phosphoric acid, NaCl, and NaHCO3 is not suitable as an auxiliary distillation reagent for testing.

[0066] Table 6 Table 6 shows that, when reagent J (a mixed solution of phosphoric acid, NaCl, and Brij35 surfactant) was used as an auxiliary distillation reagent, the peak area growth rate for low-concentration standard samples (0.002-0.01 mg / L) was 31.3-39.1%, and the peak area growth rate for high-concentration standard samples (0.02-0.1 mg / L) was 31.0-31.5%, compared to using reagent A alone as an auxiliary distillation reagent. A mixed solution of NaCl with a concentration of 150 g / L and phosphoric acid with a volume percentage of 10% was used as an auxiliary distillation reagent for low-concentration standard samples (0.002-0.01 mg / L). The peak area growth rate for the standard sample (0.02-0.1 mg / L) was 30.8-38.8%, while the peak area growth rate for the high-concentration standard sample (0.02-0.1 mg / L) was 29.1-33.0%. The former had a slightly higher peak area growth rate, but the addition of Brij35 surfactant increased the blank peak area, with a DL of 0.0004 mg / L. Repeated tests showed that the DL could not be lower than 0.0003 mg / L, indicating that the addition of Brij35 surfactant affected the determination of DL. Therefore, the test results with the addition of Brij35 surfactant did not meet the requirements.

[0067] 3. Based on the studies in 1 and 2, a mixed solution with a volume percentage of 10% phosphoric acid, a NaCl concentration of 155 g / L, and a MgSO4 concentration of 50 g / L was found to be the most effective auxiliary distillation reagent. Using the same method as in 1, and with other conditions remaining constant, reagents A and G1 were used as auxiliary distillation reagents to analyze the standard samples. The peak area results are shown in Table 7.

[0068] Table 7 As shown in Table 7, reagent G1, as an auxiliary distillation reagent, increased the peak area by 47.3%-69.6% for low-concentration standard samples (0.002-0.01 mg / L) and by 35.7%-38.1% for high-concentration standard samples (0.02-0.1 mg / L). No crystallization blockage of the flow path occurred during long-term determination, and it had no effect on the blank peak area. The DL index test also met the requirements.

[0069] This embodiment, through experiments, determined the substances and their proportions that have the best effect on the enrichment and distillation separation of volatile phenols. It also provides an auxiliary distillation reagent for the distillation separation of volatile phenols in water, which is a mixed solution of H3PO4, NaCl, and MgSO4. Under the condition that the solubility is permissible, NaCl and MgSO4 are added simultaneously to phosphoric acid as auxiliary distillation reagents. The higher the concentration of NaCl and MgSO4 added, the better the effect on improving the distillation efficiency of volatile phenols.

[0070] In the embodiments of the present invention, the best effect on improving the distillation efficiency of volatile phenols is achieved when the volume fraction of H3PO4 is 10%, the concentration of NaCl is 155 g / L, and the concentration of MgSO4 is 50 g / L in the mixed solution of H3PO4, NaCl, and MgSO4. By adding this auxiliary distillation reagent, volatile phenolic substances in water with low concentrations of volatile phenols can be enriched and separated, which is particularly important for the detection of volatile phenols in water with low concentrations of volatile phenols.

[0071] It should be noted that the terms "inlet" and "outlet" in this invention can be used with reference to the direction of liquid or gas flow, with the liquid or gas inlet being the inlet and the liquid or gas outlet being the outlet.

[0072] It should be noted that all reagents used in the embodiments of the present invention are domestically produced commercially available reagents, and the purity of the reagents is at least analytical grade.

[0073] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0074] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0075] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0076] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of embodiments of this disclosure upon considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

Claims

1. An automated water quality volatile phenol analysis system, characterized in that: It includes a first mixing module, a distillation module, a gas-liquid separation module, a condensation module, and a content detection module connected in sequence, as well as a pneumatic push-in module and an auxiliary detection module. The pneumatic push-in module is connected to the inlet of the distillation module, and the auxiliary detection module is connected to the content detection module. The first mixing module is used to prepare a mixture of sample and auxiliary distillation reagent; A pneumatic push-in module is used to deliver a mixture of sample and auxiliary distillation reagent at a stable flow rate through the inlet of the distillation module; the pneumatic push-in module includes a gas pump and a gas flow meter connected in sequence, the gas flow meter is also connected to the distillation module; a gas storage tank is provided on the connecting pipeline between the gas pump and the gas flow meter. A distillation module is used to distill a mixture of sample and auxiliary distillation reagents to form a stable gas flow of volatile phenols. The distillation module includes a heating tank and a distiller loaded inside the heating tank. The distiller has a spiral pipe structure from bottom to top. The inlet of the distiller is located at the bottom and is connected to a pneumatic push-in module and a first mixing module. The outlet of the distiller is located at the top and is connected to a gas-liquid separation module. A gas-liquid separation module is used to dry the volatile phenol gas stream from the distillation module to obtain gaseous volatile phenols; The condensation module is used to condense the gaseous volatile phenols from the gas-liquid separation module to obtain liquid volatile phenols; a degassing device is installed on the connecting pipeline between the condensation module and the content detection module. The content detection module is used to detect the liquid volatile phenols from the condensation module to obtain the content of liquid volatile phenols in the sample; The auxiliary detection module provides an auxiliary detection reagent to assist in the content detection of liquid volatile phenols in the detection module; the auxiliary distillation reagent is a mixed solution of H3PO4, NaCl, and MgSO4.

2. The automated water quality volatile phenol analysis system as described in claim 1, characterized in that: Auxiliary detection reagents include buffer solutions and colorimetric reagents.

3. The automated water quality volatile phenol analysis system as described in claim 1, characterized in that: The content detection module includes a colorimetric reaction unit and a detection unit; A colorimetric reaction unit is used to mix the liquid volatile phenols and auxiliary detection reagents to obtain the solution to be tested; The detection unit is used to detect the solution to be tested in order to obtain the content of liquid volatile phenols in the sample.

4. The automated water quality volatile phenol analysis system as described in claim 3, characterized in that: The detection unit is used to detect the optical signal of the solution to be tested, and to obtain the content of liquid volatile phenols in the sample based on the detection results of the optical signal.

5. The automated water quality volatile phenol analysis system as described in claim 1, characterized in that: The condensation module includes a water storage tank, a water pump, a refrigeration component, a liquid flow meter, a condensation chamber, and a spiral condenser tube installed in the condensation chamber; The inlet of the swirling condenser is connected to the gas-liquid separation module, and the outlet of the swirling condenser is connected to the degassing device. The outlet of the condensing chamber is connected to the inlet of the water storage tank, the outlet of the water storage tank is connected to the inlet of the water pump, the outlet of the water pump is connected to the inlet of the refrigeration component, the outlet of the refrigeration component is connected to the inlet of the liquid flow meter, and the outlet of the cold liquid flow meter is connected to the inlet of the condensing chamber.

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