Method for determining concentration of free chlorine in water

Abstract

The invention discloses a method for determining the concentration of free chlorine in water, aiming at different fluorescence intensities excited by free chlorine with different concentrations, an obtained first standard curve can indicate the fluorescence intensities without the influence of turbid substances, and an obtained table can indicate the concentration of the free chlorine in the concentration interval of the free chlorine. The difference value between solutions with different turbidity values and the first standard solution shows that the free chlorine concentration of the solution with the turbidity value is reduced or increased, then heat preservation is used before the sample solution is monitored, the influence of temperature is effectively shielded, the sample solution is valued in the first standard curve after being monitored, and meanwhile, the difference value is taken in the table; according to the present invention, the accurate free chlorine concentration can be obtained by adding the difference value to the free chlorine concentration in the first standard curve and combining the dilution ratio, the concentration is determined by using the fluorescence excitation manner, the influence of the turbid substance on the determination is small, and the influence of the turbid substance on the test result is effectively shielded through the correction value of the table.

Description

Technical Field

[0001] The present invention belongs to the technical field of water quality detection and relates to a method for determining the concentration of free chlorine in water quality. Background Art

[0002] Free chlorine generally refers to chlorine existing in the form of hypochlorous acid, hypochlorite ions or dissolved elemental chlorine. In the human body, hypochlorite ions generated by hydrogen peroxide and chloride ions in neutrophil activation can defend against pathogen invasion and exhibit unique antibacterial properties in the human immune system. Due to the strong oxidizing property of free chlorine, bleaching, and the inactivation effect on bacterial propagules, viruses, fungi and even bacterial spores, it is widely used in water treatment. However, the concentration of free chlorine in water needs to be strictly controlled.

[0003] In the field of water quality detection, when detecting the concentration of free chlorine in water by existing methods, the turbidity of the liquid in water and the difference in temperature will both affect the detection results. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for determining the concentration of free chlorine in water quality, which can effectively shield the influence of turbidity and temperature on the detection of free chlorine.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for determining the concentration of free chlorine in water quality, using TPA as a fluorescent indicator, includes the following steps;

[0007] Add free chlorine with different concentrations to the TPA buffer solution to prepare a series of first standard solutions of free chlorine;

[0008] Divide the concentration of the standard solution into multiple intervals, and prepare second standard solutions with different turbidities at the intermediate value concentration of each interval;

[0009] Keep the first standard solution and the second standard solution warm until the temperature reaches a preset constant temperature;

[0010] Under the condition that the excitation wavelength is 345 nm, detect the fluorescence intensity of each concentration of the first standard solution at the emission wavelength of 424 nm; then, with the free chlorine concentration as the abscissa and the relative fluorescence intensity as the ordinate, draw a standard curve;

[0011] Under the condition that the excitation wavelength is 345 nm, detect the fluorescence intensity of each second standard solution at the emission wavelength of 424 nm, and generate a table of different free chlorine concentration intervals, turbidities and relative fluorescence intensities;

[0012] Take a sample solution and dilute it;

[0013] Keep the diluted sample solution warm until the temperature of the sample solution remains constant at the preset temperature;

[0014] Under the condition that the excitation wavelength is 345 nm, detect the fluorescence intensity of the sample solution at the emission wavelength of 424 nm. Obtain the concentration of free chlorine according to the standard curve. Identify and determine the turbidity of the current solution through a deep learning device. Determine the current free chlorine concentration through a table. Compare with the standard curve to obtain the true difference in free chlorine concentration. Add this difference to the free chlorine concentration of the standard curve, and then calculate the final free chlorine concentration according to the dilution factor.

[0015] Further, the preset temperature is 15 - 30 °C.

[0016] Further, the preset temperature is 20 °C or 25 °C.

[0017] Further, after identifying and determining the turbidity of the current solution through a deep learning device, take the value closer to either the end value or the intermediate value of the turbidity in the table for the current turbidity.

[0018] Further, the deep learning device includes a training module and an identification and judgment module.

[0019] Further, the training module is trained by inputting a number of standard liquid pictures with different turbidities.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] In the determination method of the present invention, keeping warm before testing can effectively ensure that the test temperature remains consistent. Use a laser with a wavelength of 345 nm to excite the first standard solution and the second standard solution, and monitor the fluorescence intensity at a wavelength of 424 nm. The obtained first standard curve can show the fluorescence intensity without the influence of turbidity. The obtained table can show the difference between solutions with different turbidities and the first standard solution within the concentration range of free chlorine, indicating that the solution with this turbidity reduces or increases the free chlorine concentration. Then, keep warm in the same way before monitoring the sample solution, effectively shielding the influence of temperature. After monitoring the sample solution, take a value from the first standard curve, and at the same time take the difference in the table. Add this difference to the free chlorine concentration in the first standard curve, and then combine with the dilution factor to obtain a more accurate free chlorine concentration. This determination method uses the method of exciting fluorescence to measure the concentration. The influence of turbidity itself on the measurement is small, and through the correction value in the table, the influence of turbidity on the test result is effectively shielded. Specific Embodiments

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. That is, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0024] It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

[0025] As described in the background art, free chlorine generally refers to chlorine present in the form of hypochlorous acid, hypochlorite ions or dissolved elemental chlorine. In the human body, hypochlorite ions generated by the activation of hydrogen peroxide and chloride ions in neutrophils can defend against pathogen invasion and exhibit unique antibacterial properties in the human immune system. Since free chlorine has strong oxidizing properties, bleaching effects, and can inactivate bacterial propagules, viruses, fungi and even bacterial spores, it is widely used in water treatment. However, the concentration of free chlorine in water needs to be strictly controlled. In the field of water quality detection, when detecting the concentration of free chlorine in water by existing methods, the turbidity of the water and the difference in temperature will both affect the detection results.

[0026] Based on this, the inventor created a method for measuring the concentration of free chlorine in water in this application to solve the above technical problems.

[0027] The features and performance of the present invention will be further described in detail below in conjunction with embodiments.

[0028] Embodiment

[0029] A method for determining the concentration of free chlorine in water quality uses TPA as a fluorescent indicator and includes the following steps. Here, TPA refers to 3,5-dihydro-5-oxo-2-thiazolo[3,2-a]-pyridine 3,7-dicarboxylic acid.

[0030] Add free chlorine with different concentrations to the TPA buffer solution to prepare a series of first standard solutions of free chlorine. Here, it should be noted that the first standard solution does not contain turbidity and is the standard value.

[0031] Divide the concentration of the standard solution into multiple intervals, and prepare second standard solutions with different turbidities at the middle value concentration of each interval. Here, the second standard solution is measured in the presence of turbidity. When the concentration measured for the second standard solution is lower than that of the first standard solution, it indicates that the turbidity reduces the concentration. In this case, the difference between the two needs to be added to the standard value obtained from the standard curve. Conversely, the difference needs to be subtracted.

[0032] Keep the first standard solution and the second standard solution warm until the temperature reaches a preset temperature that remains constant. Here, all measurements are carried out at the preset temperature before measurement to avoid deviations in results caused by different temperatures. Preferably, the preset temperature can be 15 - 30 °C. Preferably, the preset temperature is 20 °C or 25 °C.

[0033] Detect the fluorescence intensity of each concentration of the first standard solution at an emission wavelength of 424 nm under the condition that the excitation wavelength is 345 nm; then plot a standard curve with the free chlorine concentration as the abscissa and the relative fluorescence intensity as the ordinate. Here, by comparing the fluorescence intensity obtained by exciting the sample solution with the standard curve, the standard value of the free chlorine concentration can be obtained.

[0034] Detect the fluorescence intensity of each second standard solution at an emission wavelength of 424 nm under the condition that the excitation wavelength is 345 nm, and generate a table of different free chlorine concentration intervals, turbidities, and relative fluorescence intensities. In this way, the difference in the free chlorine concentration can be obtained by comparing with the standard curve.

[0035] Take a sample solution and dilute it. Here, whether to dilute it can be operated according to the situation.

[0036] Keep the diluted sample solution warm until the temperature of the sample solution reaches the preset temperature that remains constant. Here, the preset temperature is the same as the warming temperature of the aforementioned first standard solution and second standard solution.

[0037] Detect the fluorescence intensity of the sample solution at an emission wavelength of 424 nm under the condition that the excitation wavelength is 345 nm. Obtain the concentration of free chlorine according to the standard curve. Identify and determine the turbidity of the current solution through the deep learning device. Determine the current free chlorine concentration through the table. Compare with the standard curve to obtain the true difference in free chlorine concentration. Add this difference to the free chlorine concentration of the standard curve, and then calculate the final free chlorine concentration according to the dilution factor. Preferably, after identifying and determining the turbidity of the current solution through the deep learning device, take the value closer to the end value and the intermediate value of the turbidity in the table. In this way, the influence difference of the measured turbidity on the free chlorine concentration can be made more accurate. Preferably, the deep learning device includes a training module and an identification and judgment module. Preferably, the training module is trained by inputting a number of standard liquid pictures with different turbidities.

[0038] In the determination method of the present invention, heat preservation before testing can effectively ensure that the test temperature remains consistent. Use a laser with a wavelength of 345 nm to excite the first standard solution and the second standard solution, and monitor the fluorescence intensity at a wavelength of 424 nm. The obtained first standard curve can show the fluorescence intensity without the influence of turbidity. The obtained table can show the difference between the solutions with different turbidities and the first standard solution within the concentration range of free chlorine, indicating that the solution with this turbidity reduces or increases the free chlorine concentration. Then, heat preservation is also used before monitoring the sample solution, effectively shielding the influence of temperature. After monitoring the sample solution, take a value from the first standard curve, and at the same time take the difference in the table. Add this difference to the free chlorine concentration in the first standard curve, and then combine with the dilution factor to obtain a more accurate free chlorine concentration. This determination method uses the method of exciting fluorescence to measure the concentration. The influence of turbidity itself on the measurement is small, and then through the correction value of the table, the influence of turbidity on the test result is effectively shielded.

[0039] The above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, and improvements made by those skilled in the art within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for determining free chlorine concentration in water, characterized in that: Using TPA as a fluorescent indicator, the steps include: Free chlorine of different concentrations was added to TPA buffer solution to prepare a series of free chlorine first standard solutions; The concentration of the standard solution is divided into a plurality of intervals, and the middle value concentration of each interval is prepared into a second standard solution of different turbidity; The first standard solution and the second standard solution are kept warm until the temperature remains constant at a preset temperature; Under the condition of an excitation wavelength of 345 nm, the fluorescence intensity of the first standard solution of each concentration at an emission wavelength of 424 nm is detected; then a standard curve is drawn with the free chlorine concentration as the abscissa and the relative fluorescence intensity as the ordinate; Under the condition of an excitation wavelength of 345 nm, the fluorescence intensity of each second standard solution at an emission wavelength of 424 nm is detected to generate a table of different free chlorine concentration ranges, turbidity and relative fluorescence intensity; Take the sample solution and dilute it; Keeping the diluted sample solution warm until the temperature of the sample solution remains constant at the preset temperature; Under the condition of excitation wavelength of 345nm, the fluorescence intensity of the sample solution is detected at an emission wavelength of 424nm. According to the concentration of free chlorine obtained from the standard curve, the turbidity of the current solution is identified and determined by the deep learning device, and the current free chlorine concentration is determined through a table. The actual free chlorine concentration difference is obtained by comparing with the standard curve, and the difference is added to the free chlorine concentration of the standard curve, and then the final free chlorine concentration is calculated according to the dilution multiple; Wherein, TPA is 3,5-dihydro-5-oxo-2-thiazolo[3,2-a]-pyridine 3,7-dicarboxylic acid.

2. A method for determining free chlorine concentration in water according to claim 1, characterized in that: The preset temperature is 15-30°C.

3. A method for determining free chlorine concentration in water according to claim 2, characterized in that: The preset temperature is 20°C or 25°C.

4. A method for determining free chlorine concentration in water according to claim 1, characterized in that: After the turbidity of the current solution is identified and determined by the deep learning device, the current turbidity is taken to be closer to the end value and the middle value of the turbidity in the table.

5. A method for determining free chlorine concentration in water according to claim 1, characterized in that: The deep learning device includes a training module and a recognition and judgment module.

6. A method for determining free chlorine concentration in water according to claim 5, characterized in that: The training module is trained by inputting a number of standard liquid images with different turbidities.