Device for detecting ammonia nitrogen in water through flow injection conductivity

Abstract

The utility model relates to a device for detecting ammonia nitrogen in water through flow injection conductivity. Comprising a mixing device for mixing a detection sample, a sodium thiosulfate solution and a sodium hydroxide solution, on-line distillation equipment for distilling the mixed solution, on-line condensation equipment for condensing the distilled mixed gas of ammonia gas and water vapor, and a degassing pipe for degassing the ammonia-containing aqueous solution generated by condensation, the conductivity detector is used for detecting the conductivity of the degassed ammonia-containing aqueous solution, the whole operation process of the device is almost free of manual intervention from sample injection to result output, personal errors are greatly reduced, and the working efficiency is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of water quality detection, in particular to a device for detecting ammonia nitrogen in water through flow injection conductivity. BACKGROUND

[0002] With the increasing demand for environmental monitoring and the development of technology, it is becoming increasingly important to quickly, accurately and efficiently determine the content of ammonia nitrogen in water. As one of the water quality indicators, the excessive presence of ammonia nitrogen not only affects the ecological balance of water bodies, but also may lead to drinking water safety problems.

[0003] Traditional ammonia nitrogen detection methods, such as the Nessler's reagent colorimetric method, although widely used due to its simplicity and low cost, have disadvantages such as complex operation, long time consumption, large reagent consumption and the need for professional operation. In addition, due to the influence of color interference and sample matrix effect, the sensitivity and accuracy of this method may be limited.

[0004] In view of this, there is a demand for a simplified process for detecting ammonia nitrogen with high efficiency and accuracy in the field of water quality detection. CONTENT OF THE INVENTION

[0005] In view of the above problems, the application provides a device for detecting ammonia nitrogen in water through flow injection conductivity, which utilizes the characteristics of ammonia molecules such as volatility, solubility in water and conductivity, aiming to improve detection efficiency and accuracy while simplifying the operation process.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0007] The application provides a device for detecting ammonia nitrogen in water through flow injection conductivity, which includes a mixing device for mixing the detection sample, sodium thiosulfate solution and sodium hydroxide solution, an online distillation equipment for distilling the mixed solution, an online condensation equipment for condensing the ammonia gas and water vapor mixed gas distilled out, a degassing pipe for degassing the ammonia-containing aqueous solution produced by condensation, and a conductivity detector for detecting the conductivity of the ammonia-containing aqueous solution after degassing.

[0008] In this way, based on the principle of flow injection analysis (FIA), the detection sample is mixed with sodium thiosulfate solution and sodium hydroxide solution, and then subjected to online distillation, online condensation and degassing, etc. By utilizing the characteristics of ammonia molecules such as volatility, solubility in water and conductivity, accurate determination of ammonia nitrogen concentration is achieved. The conductivity detector can detect very low concentration changes of ammonia nitrogen, providing higher measurement accuracy.

[0009] Compared with the traditional device and method, the application provides higher automation degree, and the whole process almost needs no manual intervention from sample injection to result output, greatly reduces human error and improves work efficiency. At the same time, the continuous flow nature makes the sample analysis can be completed in a short time, suitable for rapid screening of large quantities of samples, and real-time online monitoring in environment (such as rivers, reservoirs and other water bodies) or production (such as drinking water plants, sewage plants, beverage plants and the like).

[0010] At the same time, the experimental process is simplified, the professional skill requirement of the operator is reduced, the use of chemical reagents is reduced, the waste is reduced, and the green chemistry principle is met.

[0011] In some possible embodiments, a data processing workstation for calculating the ammonia nitrogen content in the detected sample by algorithm according to the detected conductivity is further included.

[0012] In some possible embodiments, a peristaltic pump for conveying the detection sample, the sodium thiosulfate solution, the sodium hydroxide solution and the condensed ammonia-containing aqueous solution is further included.

[0013] In a preferred embodiment, the number of peristaltic pumps is 1, which can simultaneously convey the detection sample, the sodium thiosulfate solution, the sodium hydroxide solution and the condensed ammonia-containing aqueous solution.

[0014] In some possible embodiments, the mixing device includes a three-way joint for collecting the detection sample and the sodium thiosulfate solution and the sodium hydroxide solution, and a surrounding reactor arranged at the rear end of the three-way joint.

[0015] In some possible embodiments, a waste liquid bottle for recovering the waste liquid after online distillation and conductivity detection is further included. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram of a device for detecting ammonia nitrogen in water by flow injection conductivity detection according to the application;

[0017] Figure 2 is a detection flow chart of a device for detecting ammonia nitrogen in water by flow injection conductivity detection according to the application. DETAILED DESCRIPTION

[0018] The features of the application and other related features are further described in detail by the following examples for the understanding of the skilled in the art:

[0019] Firstly, the traditional ammonia nitrogen detection has many processes that need manual intervention, so the professional skill requirement of the operator is relatively high, and the probability of error is also relatively high. At the same time, because chemical reagents are used, chemical waste exists.

[0020] The solution to this problem is a water ammonia detection system based on the principle of flow injection analysis (FIA) and combined with conductivity detection. The premise for its realization is that ammonia molecules are volatile, easily soluble in water and have conductivity, etc.

[0021] Please refer to Figure 1 and Figure 2 The detection method and the equipment used are described in detail as follows.

[0022] First, step S1 automatically inputs the detection sample by flow injection. The detection sample can be an online water quality detection sample for drainage, environment, food, etc. Step S2 inputs the detection sample and sodium thiosulfate solution, sodium hydroxide solution to form a mixed solution after pumping. Sodium thiosulfate solution and sodium hydroxide solution can be provided by a dedicated solution bottle or other dedicated equipment, which is not limited.

[0023] Specifically, the mixing device can select a three-way joint for collecting the detection sample and sodium thiosulfate solution, sodium hydroxide solution, and a surrounding reactor arranged at the rear end of the three-way joint. The three-way joint and the surrounding reactor arranged at the rear end of the three-way joint are used to mix the water sample with sodium thiosulfate solution and sodium hydroxide solution and cause chemical reaction. Preferably, the three-way joint is mixed with sodium thiosulfate solution first and then mixed with sodium hydroxide solution.

[0024] Sodium thiosulfate can remove the interference of oxidants (such as chlorine, sodium hypochlorite, etc.) in water detection, and react with chloramine (including monochloramine, dichloramine, trichloramine, etc.) to generate ammonium ion (NH4+). The original ammonium ion (NH4+) in the water sample will be converted into ammonia molecules (NH3) under alkaline conditions. Since ammonia is volatile, ammonia will escape from the solution during the subsequent online distillation process.

[0025] The reaction formula is as follows: the reaction of monochloramine and sodium thiosulfate, and the conversion of ammonium ion into ammonia molecule under alkaline conditions.

[0026] 4NH2Cl + S2O32- + 5H2O → 4NH4+ + 4Cl- + 2SO42- + 2H+;

[0027] NH4+ + OH- → NH3 + H2O.

[0028] The above reaction occurs under alkaline conditions, in which sodium hydroxide provides the necessary alkalinity to promote the reaction. Since ammonia is a volatile compound, it can easily escape from the solution under such conditions.

[0029] Further, the pumping method uses a peristaltic pump. The peristaltic pump pushes fluid by squeezing a flexible tube rather than directly contacting the liquid, thus avoiding contamination of the fluid and ensuring the accuracy of high-purity chemical analysis. Moreover, the flow rate can be easily changed by adjusting the rotation speed, which helps to maintain consistency and reproducibility of experimental conditions.

[0030] Since the fluid only contacts the hose, the peristaltic pump is easy to clean and maintain, and the hose material used is generally chemically compatible and resistant to various chemicals, making it suitable for handling different types of solutions, i.e., different test samples can be tested.

[0031] Further, it is preferred to use the same peristaltic pump for pumping. In this way, the number of devices is reduced, making the entire detection process more compact and efficient, and also reducing complexity, facilitating installation and maintenance. At the same time, such an integrated design also reduces the operational errors that may be introduced by using multiple pumps, further improving the reliability and consistency of the measurement results.

[0032] Further, step S3 performs online distillation of the mixed solution after mixing in the online distillation device to separate ammonia molecules and part of the water vapor from the water sample. The main products of online distillation are ammonia gas (NH3) and water vapor, which are formed after the test sample is converted into ammonia molecules (NH3) after reacting with sodium thiosulfate solution and sodium hydroxide solution.

[0033] The online distillation device can be a device using heating elements or heat exchangers, and can also include temperature control units, gas-liquid separation devices, etc., which will not be described in detail. After online distillation, ammonia gas (NH3) and water vapor are then introduced into the online condensation device, and the resulting waste liquid 1 is recovered into the waste liquid bottle.

[0034] Further, step S4 introduces ammonia gas (NH3) and water vapor into the online condensation device to form an ammonia-containing aqueous solution. The online condensation device can use cooling coils, heat exchangers, or cooling jackets using circulating cooling liquids. The cooling medium can be cold water, ice water mixture, or refrigerant, the purpose of which is to quickly reduce the gas temperature to promote the condensation of ammonia gas (NH3) and water vapor into liquid. Throughout the process, by optimizing the condensation conditions (such as temperature, pressure, and gas flow rate), efficient recovery of ammonia gas can be ensured, thereby improving the accuracy and reliability of the final measurement results. The main purpose is to form an ammonia-containing aqueous solution that is convenient for detection, and the specific device principle form will not be described in detail.

[0035] After condensation, bubbles or dissolved gas will be left, which is degassed. Specifically, degassing tube can be used for degassing, and the specific degassing method can be selected by using the conventional technical means in the industry, and details will not be described here. The purpose is to effectively remove air bubbles in the sample, improve the data quality and stability of the entire analysis process.

[0036] When the aqueous ammonia solution is transported to the degassing tube, it is preferably transported by the peristaltic pump as described above, which uses the same peristaltic pump to transport as described above, which will not be described here.

[0037] After the aqueous ammonia solution is treated as described above, the conductivity is detected by a conductivity detector. The conductivity detector is an analytical instrument for measuring the conductivity of a solution, and its basic working principle is based on the ability of ions in the solution to conduct current. When two electrodes are inserted into a solution containing electrolytes, a direct current or alternating current voltage applied between the two electrodes will generate a current between the two electrodes. The conductivity (G) of the solution is inversely proportional to the resistivity (p), and can be calculated by the following formula: G = 1 / R = σ·A / L, where R is the resistance, σ is the conductivity, A is the cross-sectional area between the electrodes, and L is the distance between the electrodes. The waste liquid 2 generated after detection is then recovered into a waste liquid bottle.

[0038] Due to the change of ammonia content in the aqueous ammonia solution, the conductivity changes. The conductivity detector can accurately measure this change, and the detection value is then transmitted to a data processing workstation and converted into an ammonia nitrogen concentration value by a pre-calibrated standard curve. That is, the ammonia nitrogen content in the original water sample is calculated by an algorithm, which not only improves the detection efficiency, but also ensures the accuracy and reliability of the results, and is very suitable for large-scale water quality monitoring and research work.

[0039] Compared with traditional devices and methods, the present application provides higher automation, and the entire process from sample injection to result output almost does not require manual intervention, greatly reducing human error and improving work efficiency. At the same time, the continuous flow nature allows sample analysis to be completed in a short time, which is suitable for rapid screening of large quantities of samples, as well as real-time online monitoring in the environment (such as rivers, reservoirs, etc. Water body) or production (such as drinking water plant, sewage plant, beverage plant, etc.).

[0040] At the same time, the experimental process is simplified, the professional skill requirement of the operator is reduced, the use of chemical reagents is reduced, the waste is reduced, and the green chemistry principle is met.

[0041] As described above, the present application protects a device for flow injection conductivity detection of ammonia nitrogen in water, and all technical solutions similar or similar to the present application shall be shown to fall within the protection scope of the present application.

Claims

1. A device for determining ammonia nitrogen in water by flow injection conductometric detection, characterized in that, The application relates to a device for detecting ammonia nitrogen in a sample, which comprises a mixing device for mixing the sample with sodium thiosulfate solution and sodium hydroxide solution, an online distillation device for distilling the mixed solution, an online condensation device for condensing the ammonia gas and water vapor mixed gas, a degassing tube for degassing the ammonia-containing water solution, and a conductivity detector for detecting the conductivity of the degassed ammonia-containing water solution.

2. The device for detecting ammonia nitrogen in water by flow injection and conductance according to claim 1, characterized in that, The application also relates to a data processing workstation for calculating the ammonia nitrogen content in the sample according to the detected conductivity through an algorithm.

3. The device for detecting ammonia nitrogen in water by flow injection and conductance according to claim 1, characterized in that, The application also relates to a peristaltic pump for conveying the sample, the sodium thiosulfate solution, the sodium hydroxide solution and the ammonia-containing water solution after condensation.

4. The device for detecting ammonia nitrogen in water by flow injection and conductance according to claim 1, characterized in that, The mixing device comprises a tee joint for collecting the sample, the sodium thiosulfate solution and the sodium hydroxide solution, and a surrounding reactor arranged at the rear end of the tee joint.

5. The device for detecting ammonia nitrogen in water by flow injection and conductance according to claim 1, wherein, The application also relates to a waste liquid bottle for recovering the waste liquid after the online distillation and the conductivity detection.

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