An integrated extraction on-line anionic surfactant analyzer and method

Abstract

This invention relates to the field of environmental monitoring and discloses an analyzer for online anionic surfactant extraction using an integral extraction method. The analyzer includes a reactor, a feed / discharge assembly, a first injection pump, and a first control valve. An exhaust pipe is installed at the top of the reactor. The feed / discharge assembly is connected to the reactor and several solvents required for the reaction, respectively. The first control valve includes a common terminal and two control terminals. The common terminal of the first control valve is connected to the first injection pump, and the two control terminals are connected to a chloroform solution and the reactor, respectively. This invention also discloses a method for online anionic surfactant extraction using an integral extraction method, comprising the following steps: S1, emptying the liquid in the reactor; S2, rinsing and emptying; S3, sampling; S4, adding reagents; S5, integral extraction; S6, colorimetric analysis and calculation of the sample concentration. This invention uses an integral extraction method, eliminating the need for multiple extraction steps, and achieving a high extraction rate while reducing the amount of chloroform used and the measurement time.

Description

Technical Field

[0001] This invention relates to the field of environmental monitoring, and in particular to an analyzer and method for integral extraction of online anionic surfactants. Background Technology

[0002] In the field of environmental monitoring, the content of anionic surfactants is an important indicator for water environment monitoring. Anionic surfactants are the main active ingredients in common synthetic detergents. Most surfactants in natural water and domestic sewage originate from pollution caused by their use in synthetic detergents. In addition, lubricants, softeners, and antistatic agents used in industry, as well as emulsifiers used in agriculture, also contribute to anionic surfactant pollution. Anionic surfactants can form negatively charged micelles in water, exhibiting surface activity and producing persistent foam that covers the water surface, affecting oxygen transport, reducing dissolved oxygen levels, leading to water quality deterioration, and impacting aquatic life growth. When their concentration exceeds a certain level, they can also harm human health. Given the harmful effects of anionic surfactants, they are a crucial indicator of water pollution. Accurately measuring anionic surfactants in environmental water quality is of significant practical importance, providing a more reliable scientific basis for environmental protection and remediation efforts.

[0003] Currently, the main methods for determining anionic surfactants include spectrophotometry, electrochemical analysis, fluorescence analysis, and high-performance liquid chromatography (HPLC). Among these, spectrophotometry is widely used, and the national standard method for determining anionic surfactants is the methylene blue spectrophotometric method. Due to the properties of chloroform and the limitations of online testing time, achieving online extraction of anionic surfactants in water quality monitoring has always been a challenge. Most existing extraction methods involve mixing the water sample with methylene blue and then directly mixing and extracting it with chloroform. For example, Chinese invention patent application number 201710023604.1 describes an anionic detergent detection system, which includes a peristaltic pump, a sample extraction module, a sample separation module, and an anion detection module. The sample extraction module includes a sample mixing device and a primary extraction device connected in sequence. The primary extraction device is an extraction device that mixes the sample with a basic methylene blue solution and then with chloroform. While existing extraction methods are simple to operate, they have low extraction rates and require multiple extractions, significantly increasing the amount of chloroform used and the testing time. Therefore, there is an urgent need for a more effective detection method and analyzer to adapt to the ever-increasing detection volume. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an analyzer and method for online extraction of anionic surfactants using integral extraction. This method can eliminate the need for multiple extraction processes, and achieve a high extraction rate while reducing the amount of chloroform used and the measurement time.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention discloses an online anionic surfactant analyzer using integral extraction, comprising a reactor with an exhaust pipe at its upper end, a feed / discharge assembly connected to the reactor and several solvents required for the reaction, a first injection pump, and a first control valve including a common terminal and two control terminals. The common terminal of the first control valve is connected to the first injection pump, and the two control terminals are connected to a chloroform solution and the reactor, respectively.

[0007] Furthermore, the control end of the first control valve is connected to the upper end of the reactor via a small-diameter Teflon tube, and the small-diameter Teflon tube installed on the reactor is located above the surface of the reaction liquid.

[0008] Further, the feed and discharge assembly includes: a second injection pump; a multi-channel control valve, which includes a common terminal and several control terminals; the common terminal of the multi-channel control valve is connected to the second injection pump, and the several control terminals are respectively connected to the reactor, the sample to be tested, air, pure water, a waste outlet, a standard solution, and several reagents; a micro peristaltic pump, one end of which is connected to the waste outlet, and the other end of which is connected to one control terminal of the multi-channel control valve; a diaphragm air pump; one end of the diaphragm air pump is connected to the reactor; and a second control valve, which includes a common terminal and two control terminals, the common terminal of which is connected to the other end of the diaphragm air pump, and the two control terminals are respectively connected to pure water and air.

[0009] Furthermore, the reactor includes a reaction tank, with corresponding LED lights and detectors arranged on both sides of the reaction tank; the wavelength of the LED lights is 655nm-665nm.

[0010] Furthermore, a stirring motor is installed below the reactor, and a stir bar is installed on the output shaft of the stirring motor, with the stir bar located inside the reactor.

[0011] Furthermore, a liquid level sensor is also installed on the reactor.

[0012] This invention also discloses a method for integral extraction of anionic surfactants in the online process, comprising the following steps:

[0013] S1. Drain the liquid from the reactor;

[0014] S2. Extract a sample to rinse all components of the analyzer and then drain the air.

[0015] S3. Sampling: Extract a set volume of sample into the reactor;

[0016] S4. Adding chemicals: Add the solutions required for the reaction in sequence;

[0017] S5. Integral Extraction: A sufficient volume of chloroform is drawn into a syringe pump, which pushes the chloroform into the reactor. The chloroform passes through the sample water layer as droplets, extracting the sample in the water layer and causing it to sink to the bottom of the reactor. This extraction process is repeated until all the chloroform is injected or the water layer sample is completely extracted. The volume of chloroform is determined by a fixed value that, after multiple tests and verifications, ensures complete extraction across the highest concentration range and that the liquid level remains above the light path. This volume does not vary with different concentrations.

[0018] S6. Perform colorimetric analysis and calculate the sample concentration.

[0019] Further, in the S4 dosing step, alkaline buffer solution R1 is added first, followed by methylene blue R2, and finally pure water H1. In the S5 integral extraction step, the injection pump pushes chloroform into the reactor at a rate of 0.35 ml / min-0.45 ml / min. The criteria for determining whether the aqueous sample extraction is complete are: when extraction is complete, the absorbance and sample concentration satisfy the Lambert-Beer law; or, by observing the absorbance curve, the real-time absorbance curve tends to be stable when extraction is complete, while the curve continuously rises when extraction is incomplete.

[0020] Further, in step S6, an LED lamp with a wavelength of 655nm-665nm and a detector are used to colorimetrically read the light signal value in the chloroform layer, and the light signal value is converted into absorbance. The concentration of the sample is calculated based on the stored blank and standard solution correction values ​​and the absorbance value of the sample read. The blank correction value and standard solution correction value are obtained as follows: using steps S1-S6 above, where in step S3, when the sampling solution is pure water, the measured absorbance value is the blank correction value; when the sampling solution is a standard solution, the measured absorbance value is the standard solution correction value; when the sampling solution is a sample solution, the measured absorbance value is the sample absorbance. The sample concentration is calculated using the formula: Sample concentration = Standard solution concentration * (Sample absorbance - Blank absorbance) / (Standard solution absorbance - Blank absorbance).

[0021] Furthermore, it also includes step S7, cleaning and purging: a set amount of pure water is drawn into the reactor, then the drain is opened, air is drawn out to purge the pure water from the reactor, and the cleaning and purging is repeated several times.

[0022] The advantages of this invention are:

[0023] This invention utilizes the precise control of titration speed by an injection pump, using the first injection pump as the chloroform injection device. During the extraction process, low-speed titration allows the chloroform droplets to fully remove the anionic surfactants in the aqueous sample, and the extraction is carried out in an integral manner, eliminating the need for multiple extraction processes. This reduces the amount of chloroform used and the measurement time while achieving a high extraction rate. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention.

[0025] Explanation of key component symbols:

[0026] 1. Reactor; 11. Exhaust pipe; 12. Reaction tank; 13. LED light; 14. Detector; 15. Stirring motor; 16. Stirrer.

[0027] 2. First injection pump;

[0028] 3. First control valve;

[0029] 4. Second injection pump;

[0030] 5. Multi-channel control valve;

[0031] 6. Miniature peristaltic pump;

[0032] 7. Diaphragm air pump;

[0033] 8. Second control valve;

[0034] 9. Liquid level sensor. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1 As shown, this invention discloses a method for integral extraction of anionic surfactants online, comprising the following steps:

[0037] S1, Drain the liquid in reactor 1.

[0038] S2. Extract the sample to rinse all parts of the analyzer and then drain the air.

[0039] S3. Sampling: Extract a set volume of sample into reactor 1.

[0040] S4. Adding reagents: Add the solutions required for the reaction in the following order. Specifically, first add the alkaline buffer solution R1, then add the methylene blue R2, and finally add the pure water H1.

[0041] S5. Integral Extraction: A sufficient volume of chloroform is injected into the syringe pump, which pushes the chloroform into reactor 1. The chloroform passes through the sample water layer as droplets, extracting the sample in the water layer and causing it to sink to the bottom of the reactor. This extraction process is repeated until all the chloroform is injected or the water layer sample is completely extracted. The volume of chloroform is determined by a fixed value that, after multiple tests and verifications, ensures complete extraction across the highest concentration range and that the liquid level is above the light path range. This volume does not vary with different concentrations. The syringe pump pushes the chloroform into the reactor at a rate of 0.35 ml / min - 0.45 ml / min. The criterion for determining complete extraction of the water layer sample is: when extraction is complete, the absorbance and sample concentration satisfy the Lambert-Beer law, or, as observed from the absorbance curve, the real-time absorbance curve tends to be stable when extraction is complete, while the curve continuously rises when extraction is incomplete.

[0042] S6. Colorimetric analysis and calculation of sample concentration. Specifically, during colorimetric analysis, a 660nm wavelength LED lamp 13 and detector 14 are used to read the light signal value in a chloroform layer, and the light signal value is converted into absorbance. The sample concentration is calculated based on the stored blank and standard solution correction values ​​and the read sample absorbance value. Obtaining blank and standard solution correction values: using steps S1-S6 above, where in step S3, when the sample solution is pure water, the measured absorbance value is the blank correction value; when the sample solution is a standard solution, the measured absorbance value is the standard solution correction value; when the sample solution is a sample solution, the measured absorbance value is the sample absorbance. The sample concentration is calculated using the formula: Sample concentration = Standard solution concentration * (Sample absorbance - Blank absorbance) / (Standard solution absorbance - Blank absorbance).

[0043] S7. Cleaning and purging: Draw a set amount of pure water into reactor 1, then open the drain outlet and draw air to purge the pure water from reactor 1. Repeat the cleaning and purging process several times.

[0044] like Figure 1 As shown, the present invention also discloses an analyzer for online extraction of anionic surfactants by integral extraction, which includes a reactor 1, a feed and discharge assembly, a first injection pump 2, and a first control valve 3.

[0045] The reactor 1 is equipped with an exhaust pipe 11 at the upper end to facilitate the injection of solution into the reactor 1.

[0046] The feed and discharge components are connected to reactor 1 and several solvents required for the reaction, respectively, and are used to inject the solutions required for the reaction into reactor 1 in a set order and volume.

[0047] The first control valve 3 includes a common terminal and two control terminals. The common terminal of the first control valve 3 is connected to the first injection pump 2, and the two control terminals are connected to the chloroform solution and the reactor 1, respectively. The first injection pump 2 is used to slowly inject chloroform into the reactor 1 in a droplet manner to extract the anionic surfactant. Because the injection pump has high precision and is easy to control, it is used as the chloroform injection device.

[0048] In order to enable chloroform to pass through the sample water layer in the form of droplets, extract and carry away the sample in the water layer, and sink to the bottom of reactor 1, the control end of the first control valve 3 for injecting chloroform is connected to the upper end of reactor 1 through a small-diameter Teflon tube. The small-diameter Teflon tube installed on reactor 1 is located above the reaction liquid surface.

[0049] Specifically, the feeding and discharging assembly includes: a second injection pump 4, a multi-channel control valve 5, a micro peristaltic pump 6, a diaphragm air pump 7, and a second control valve 8.

[0050] The multi-channel control valve 5 includes a common terminal and several control terminals. The common terminal of the multi-channel control valve 5 is connected to the second injection pump 4, and the several control terminals are respectively connected to the reactor 1, the sample S to be tested, air, pure water H1, waste outlet W1, standard solution C, and several reagents R. In use, the second injection pump 4 first extracts the required solution into the second injection pump 4, and then injects the solution in the second injection pump 4 into the reactor 1 according to the set volume, and then discharges the excess solution.

[0051] One end of the miniature peristaltic pump 6 is connected to the waste discharge port W2, and the other end is connected to one control terminal of the multi-channel control valve 5. It is used to provide driving force when discharging waste liquid from reactor 1.

[0052] The second control valve 8 includes a common terminal and two control terminals. The common terminal is connected to the other end of the diaphragm air pump 7, and the two control terminals are connected to pure water (H2) and air, respectively. One end of the diaphragm air pump 7 is connected to the reactor 1 to inject pure water (H2) for cleaning the reactor 1, providing driving force.

[0053] Specifically, reactor 1 includes a reaction tank 12, and corresponding LED lights 13 and detectors 14 are arranged on both sides of the reaction tank 12; wherein, the wavelength of the LED light 13 is 660nm.

[0054] To facilitate efficient mixing of the solution during the reaction, a stirring motor 15 is installed at the bottom of the reactor 1, and a stir bar 16 is installed on the output shaft of the stirring motor 15. The stir bar 16 is located inside the reactor 1.

[0055] Reactor 1 is also equipped with a liquid level sensor 9, mainly to prevent the absence of reagents or standard solutions during automatic testing. An alarm will be triggered when no reagents or standard solutions are detected during automatic testing. The program can detect that the internal tubing is empty through the liquid level sensor 9 during sample injection, thus making a judgment that there is a lack of solvent.

[0056] To better understand this invention, this embodiment, using an analyzer and detection method, takes sample S as an example to introduce the operating principle of the analyzer and the detection method:

[0057] In this embodiment, the multi-channel control valve 5 has ten control terminals (01 to 10), which are sequentially connected to the reaction tank 12, reagents R1, R2, and R3, one end of the micro peristaltic pump 6, pure water H1, sample S, standard solution C, waste outlet W1, and air. The operating steps are as follows:

[0058] 1. Emptying reactor 1: At the start of the analysis, turn on the multi-channel control valves 5 at points 01 and 05 and the micro peristaltic pump 6, and turn on the stirring motor 15 (stirring continues during the analysis) to empty the solution inside reactor 1. After emptying, turn off the micro peristaltic pump 6 and valves 01 and 05 in sequence.

[0059] 2. Rinsing: Turn on the multi-channel control valve 5 at position 07 and the second injection pump 4 to extract a set volume of sample S to rinse the internal flow path of the second injection pump 4 and the multi-channel control valve 5. Turn off position 07, turn on position 09 and the second injection pump 4 to discharge the rinsed sample into waste liquid W1, and turn off position 09.

[0060] 3. Sampling: Turn on the multi-channel control valve 5 at position 07 and the second injection pump 4 to extract the set volume of sample. Turn off 07, turn on 01 and the second injection pump 4 to discharge the set volume of sample into reactor 1. Turn off 01, turn on 09, and discharge the excess sample into waste liquid W1. Then turn off 09.

[0061] 4. Add reagent R1 (alkaline buffer solution): Open the multi-channel control valve 5 at position 02 and the second injection pump 4 to draw the set volume of reagent R1. Close 02, open 01 and the second injection pump 4 to discharge the set volume of reagent R1 into reactor 1. Close 01, open 09, and discharge the excess reagent R1 into waste liquid W1. Then close 09.

[0062] 5. Add reagent R2 (methylene blue): Open the multi-channel control valve 5 at position 03 and the second injection pump 4 to draw the set volume of reagent R2. Close 03, open 01 and the second injection pump 4 to discharge the set volume of reagent R2 into reactor 1. Close 01, open 09, and discharge the excess reagent R2 into waste liquid W1. Then close 09.

[0063] 6. Add pure water H1: Open the multi-channel control valve 5 at position 06 and the second injection pump 4 to draw the set volume of pure water H1. Close 06, open 01 and the second injection pump 4 to discharge the set pure water H1 into reactor 1 so that the reagent and sample can be completely pushed into reactor 1. Close 01.

[0064] 7. Integral Extraction: The first control valve 3 is opened, and the second syringe pump 4 is activated, drawing the required volume of chloroform into the syringe (this volume is sufficient to completely extract the sample and its volumetric energy exceeds the optical path inside reactor 1). The first control valve 3 is closed, and the second syringe pump 4 slowly pushes the chloroform into reactor 1. Droplets will slowly form at the inlet inside reactor 1 until gravity reaches the standard for dripping, at which point they will drip directly into the solution. The chloroform droplets will pass through the water layer containing the sample above reactor 1 by gravity, extracting and carrying away the sample from the water layer until they sink to the bottom. This extraction process is repeated to completely extract the sample from the water layer using an integral convergence method. This extraction process is relatively long, generally taking about 12–20 minutes.

[0065] 8. Colorimetric analysis: After extraction, the second injection pump 4 stops operating, and the 660nm wavelength LED lamp 13 and detector 14 in the optical components work to directly read the light signal value at this time in the trichloromethane layer and convert the light signal value into the absorbance at this time.

[0066] 9. Calculation: Calculate the concentration of the sample based on the stored blank and standard solution correction values ​​and the absorbance value of the sample read.

[0067] 10. Draining: Open the multi-channel control valves at points 5 (01, 05) and the micro peristaltic pump 6 to drain the solution inside reactor 1. After draining, close the micro peristaltic pump 6 and valves 01 and 05 in sequence.

[0068] 11. Cleaning: Open the second control valve 8 and the diaphragm air pump 7 to draw pure water H2 into the reactor 1 for cleaning. After the time for drawing pure water H2 is reached, close the second control valve 8 and completely push the internal pure water into the reactor 1 with air. After completion, close the diaphragm air pump 7.

[0069] The emptying and cleaning process is performed according to the set number of times until cleaning is complete, at which point all actions stop.

[0070] In summary, this invention utilizes the precise control of titration speed by an injection pump, using the injection pump as the drug delivery device for chloroform. During the extraction process, low-speed titration allows the chloroform droplets to fully remove the anionic surfactants in the aqueous sample, and extraction is performed in an integral, cumulative manner, eliminating the need for multiple extraction steps. This reduces the amount of chloroform used and the measurement time while achieving a high extraction rate.

[0071] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of integrating extraction of anionic surfactants on-line, characterized by: The following steps are performed using an online anionic surfactant analyzer employing an integrating extraction method, wherein the online anionic surfactant analyzer includes: A reactor, wherein an exhaust pipe is provided at the upper end of the reactor; The feed and discharge assembly is connected to the reactor and several solvents required for the reaction, respectively. First injection pump; A first control valve, comprising a common terminal and two control terminals; the common terminal of the first control valve is connected to a first injection pump, and the two control terminals are respectively connected to a chloroform solution and a reactor; The steps include: S1. Drain the liquid from the reactor; S2. Extract a sample to rinse all components of the analyzer and then drain the air. S3. Sampling: Extract a set volume of sample into the reactor; S4. Adding chemicals: Add the solutions required for the reaction in sequence; S5. Integral Extraction: A sufficient volume of chloroform is drawn into the first syringe pump, which pushes the chloroform into the reactor at a rate of 0.35 ml / min - 0.45 ml / min. The chloroform passes through the sample water layer in droplet form, extracting the sample in the water layer and causing it to sink to the bottom of the reactor. This extraction process is repeated until all the chloroform has been injected or the water layer sample has been completely extracted. S6. Perform colorimetric analysis and calculate the sample concentration.

2. The method for integral extraction of online anionic surfactants according to claim 1, characterized in that: The control end of the first control valve is connected to the upper end of the reactor via a small-diameter Teflon tube, which is positioned above the surface of the reaction liquid.

3. The method for integral extraction of online anionic surfactants according to claim 1, characterized in that: The feeding and discharging assembly includes: Second injection pump; A multi-channel control valve includes a common terminal and several control terminals; the common terminal of the multi-channel control valve is connected to a second injection pump, and the several control terminals are respectively connected to a reactor, a sample to be tested, air, pure water, a waste outlet, a standard solution, and several reagents. A miniature peristaltic pump, one end of which is connected to a waste discharge port, and the other end of which is connected to a control terminal of the multi-channel control valve; Diaphragm air pump; one end of the diaphragm air pump is connected to the reactor; The second control valve includes a common end and two control ends. The common end is connected to the other end of the diaphragm air pump, and the two control ends are connected to pure water and air, respectively.

4. The method of claim 1, wherein the method is an in-line anionic surfactant extraction method. The reactor includes a reaction tank, with corresponding LED lights and detectors installed on both sides of the reaction tank; the wavelength of the LED lights is 655nm-665nm.

5. The method of claim 1, wherein the method is an in-line anionic surfactant extraction method. A stirring motor is installed below the reactor, and a stir bar is installed on the output shaft of the stirring motor. The stir bar is located inside the reactor.

6. The method of claim 1, wherein the method is an in-line anionic surfactant extraction method. The reactor is also equipped with a liquid level sensor.

7. The method for integral extraction of online anionic surfactants according to claim 1, characterized in that: In the S4 dosing step, alkaline buffer solution R1 is added first, followed by methylene blue R2, and finally pure water H1 is added. In the S5 integral extraction step, the criteria for determining whether the water layer sample is completely extracted are: when the extraction is complete, the absorbance and the sample concentration satisfy the Lambert-Beer law, or by observing the absorbance curve, the real-time absorbance curve will tend to be stable when the extraction is complete, and the curve will continue to rise when the extraction is incomplete.

8. The method for integral extraction of online anionic surfactants according to claim 1, characterized in that: In step S6, an LED lamp with a wavelength of 655nm-665nm and a detector are used to colorimetrically read the light signal value in a chloroform layer, and the light signal value is converted into absorbance. The concentration of the sample is calculated based on the stored blank correction value and standard solution correction value, as well as the absorbance value of the sample. The blank correction value and standard solution correction value are obtained by using the steps S1-S6 above. In step S3, when the sampling solution is pure water, the measured absorbance value is the blank correction value; when the sampling solution is a standard solution, the measured absorbance value is the standard solution correction value; when the sampling solution is a sample solution, the measured absorbance value is the sample absorbance. The concentration of the sample is calculated using the formula: Sample concentration = Standard solution concentration * (Sample absorbance - Blank absorbance) / (Standard solution absorbance - Blank absorbance).

9. The method for integral extraction of online anionic surfactants according to claim 1, characterized in that: It also includes step S7, cleaning and purging: a set amount of pure water is drawn into the reactor, then the drain is opened, air is drawn out to purge the pure water from the reactor, and the cleaning and purging is repeated several times.

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