Method for measuring water hardness of seawater desalination project

Abstract

The invention provides a method for measuring the water hardness of a seawater desalination project, which comprises the following steps: calibrating an electrode by using standard solutions with different calcium and magnesium ion concentrations to obtain standard curves in different concentration ranges, with potential values in the standard curves as ordinates and concentrations as abscissas; and inserting the calibrated water hardness composite electrode into a to-be-detected seawater desalination engineering water quality sample, and calculating the hardness concentration of the to-be-detected seawater desalination engineering water quality sample through the potential value. The hardness concentration of the water quality sample of the seawater desalination project to be measured is measured by using the water hardness composite electrode, so that the problem of hidden dangers in the aspects of safety, quality and environmental protection existing in measurement of the water quality hardness of the seawater desalination project by using an existing chrome black T method and an acid chrome blue K method is solved.

Description

Technical Field

[0001] The present application belongs to the technical field of water quality analysis for seawater desalination projects, and specifically relates to a method for measuring the hardness of water quality in seawater desalination projects. Background Art

[0002] Desalination is the production of fresh water by desalinating seawater. It is an open-source incremental technology for realizing the utilization of water resources, turning it into fresh water that can be used for drinking, industrial use, etc. In this process, the hardness of the incoming and outgoing water needs to be strictly controlled.

[0003] When used for industrial water, appropriate hardness can regulate water quality and alleviate acid corrosion. However, if the water hardness is high, it will cause scaling in the pipeline and increase the operating pressure of the water, resulting in increased load on the pump and affecting the stable operation of the subsequent desalination process. The hardness content of the inlet water directly affects the amount of scale inhibitors. Insufficient scale inhibitors due to inaccurate hardness measurement will cause blockage of the reverse osmosis membrane, leading to further damage. When used as domestic water, too high hardness will affect human health.

[0004] Therefore, it is very important to measure the hardness in water accurately, stably and quickly. At present, the hardness in water is analyzed by titration using the chrome black T method and the acid chrome blue K method. The reagents ammonia and hydrochloric acid used in this method are highly corrosive, and the glassware in contact during the operation is fragile, which has a high risk factor. There are a lot of manual operations during the test, the endpoint judgment is uncertain, and it is not suitable for use in turbid and colored water samples.

[0005] In summary, the chrome black T method and acid chrome blue K method for measuring water hardness in seawater desalination projects have hidden dangers in terms of safety, quality and environmental protection. It is necessary to seek a new method with less manual operation, no use of dangerous reagents, fast and stable. Summary of the invention

[0006] In view of this, the embodiment of the present application is committed to providing a method for measuring the hardness of water quality in seawater desalination projects. The hardness concentration of the water quality sample of the seawater desalination project to be measured is obtained by using a water hardness composite electrode to solve the problems of safety, quality and environmental protection in measuring the hardness of water quality in seawater desalination projects using the existing chrome black T method and acid chrome blue K method.

[0007] The present application provides a method for measuring the hardness of water quality in a seawater desalination project, and the method comprises: calibrating an electrode using standard solutions with different calcium and magnesium ion concentrations to obtain a standard curve with different concentration ranges, wherein the potential value in the standard curve is the ordinate and the concentration is the abscissa; inserting the calibrated water hardness composite electrode into a seawater desalination project water quality sample to be measured, and calculating the hardness concentration of the seawater desalination project water quality sample to be measured through the potential value.

[0008] In a specific embodiment of the present application, standard solutions of different calcium and magnesium ion concentrations are used to calibrate the electrode to obtain standard curves in different concentration ranges, including: preparing standard solutions of water hardness of 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L, respectively, and adjusting the pH to below 6.00 with hydrochloric acid so that calcium and magnesium exist in ionic form rather than colloidal form; adding a corresponding volume of 1000 mg / L water hardness standard solution, recording the stable potential after each addition, and drawing a standard curve on a coordinate paper with the potential value as the ordinate and the concentration as the abscissa, with the coordinate origin and the measured value of the standard solution as two points.

[0009] In a specific embodiment of the present application, a calibrated water hardness composite electrode is inserted into a seawater desalination project water quality sample to be tested, and the hardness concentration of the seawater desalination project water quality sample to be tested is calculated by the potential value, including: measuring 100 mL of the seawater desalination project water quality sample to be tested into a clean beaker, and adjusting the pH to below 6.00; connecting the water hardness composite electrode and the ion meter, measuring the potential value of the seawater desalination project water quality sample to be tested, finding the concentration corresponding to the potential value on the coordinate paper, and directly reading the result as the hardness concentration in the water sample.

[0010] In one specific embodiment of the present application, the water hardness composite electrode is used as an online meter.

[0011] In a specific embodiment of the present application, the water hardness composite electrode includes an electrode cap, a cable, a filling hole, an electrode shell, a reference cell, an electrode interior and a sensitive component. The electrode cap is sleeved on the outside of the cable, and the cable is connected to the inside of the electrode. The inside of the electrode is connected to the sensitive component. The inside of the electrode is arranged inside the electrode shell. The reference cell is arranged in the gap between the inside of the electrode and the electrode shell. The filling hole is arranged on the electrode shell. The reference solution is added to the reference cell through the filling hole. When the water hardness composite electrode is inserted into the water quality sample of the seawater desalination project to be tested, the electrode shell and the sensitive component in the water hardness composite electrode are in direct contact with the water quality sample of the seawater desalination project to be tested.

[0012] The beneficial effect of the technical solution of the present application is that the hardness concentration of the water quality sample of the seawater desalination project to be measured is obtained by using the water hardness composite electrode. Since the measurement method no longer uses the reagents in the titration method, especially toxic reagents such as chrome black T and chrome blue K, the sample preparation is fast and simple, no toxic and harmful reagents are used during sample preparation, the waste liquid is easy to handle, and no hazardous waste liquid is generated. It is also safer for analysts, and the use of manual operations and chemicals is reduced as much as possible, making it fast, accurate, safe, and environmentally friendly. In addition, the water hardness composite electrode has the advantages of fast analysis speed, high analysis accuracy, and wide analysis range. The average time for analyzing a sample using the measurement method provided in the embodiment of the present application is reduced from 15 minutes to less than 5 minutes, which effectively improves the measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Shown is a flow chart of a method for measuring water hardness in a seawater desalination project provided in one embodiment of the present application.

[0014] Figure 2 Shown is a schematic diagram of the structure corresponding to a water hardness composite electrode provided by an embodiment of the present application during measurement.

[0015] Figure 3 Shown is a schematic structural diagram of a water hardness composite electrode provided in one embodiment of the present application. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0017] At least one embodiment of the present application provides a method for measuring the hardness of water in a seawater desalination project, such as Figure 1 As shown, the method for measuring the water hardness of the seawater desalination project includes the following steps.

[0018] S1: Use standard solutions with different calcium and magnesium ion concentrations to calibrate the electrode to obtain standard curves with different concentration ranges. The potential value is the ordinate and the concentration is the abscissa.

[0019] S2: Insert the calibrated water hardness composite electrode into the water quality sample of the seawater desalination project to be tested, and calculate the hardness concentration of the water quality sample of the seawater desalination project to be tested through the potential value.

[0020] It should be noted that the water hardness composite electrode is an electrode used to measure hardness, which is mainly achieved by measuring the calcium and magnesium ions in seawater and its desalinated water. It meets the characteristics of being fast, stable and environmentally friendly.

[0021] The water hardness composite electrode uses the electrode method to measure directly. A large number of experiments have proved that it has the same accuracy as the titration method, can avoid many shortcomings of the titration method, and is suitable for the water hardness concentration detection of seawater desalination project water quality.

[0022] According to the Nernst equation, the voltage value is linearly related to the ratio of calcium and magnesium ions in the sample to be tested / reference solution. Since the concentration of calcium and magnesium ions in the reference solution is known, the voltage value is one-to-one corresponding to the calcium and magnesium ions in the solution to be tested. Electrodes are the way to detect the voltage value in the above system.

[0023]

[0024] In formula 1: E—electrode potential; E 0 —standard electrode potential; R—gas constant (8.31441 J / mol*K); T—temperature; F—Faraday constant (96486.7 C / mol); a—activity of the ion to be measured; n—number of electron transfers.

[0025] According to the technical solution provided in the embodiment of the present application, the hardness concentration of the water quality sample of the seawater desalination project to be measured is obtained by using the water hardness composite electrode. Since the measurement method no longer uses the reagents in the titration method, especially toxic reagents such as chrome black T and chrome blue K, the sample preparation is fast and simple, no toxic and harmful reagents are used during sample preparation, the waste liquid is easy to handle, and no hazardous waste liquid is generated. It is also safer for analysts, and the use of manual operations and chemicals is reduced as much as possible, making it fast, accurate, safe, and environmentally friendly. In addition, the water hardness composite electrode has the advantages of fast analysis speed, high analysis accuracy, and wide analysis range. The average time for analyzing a sample using the measurement method provided in the embodiment of the present application is reduced from 15 minutes to less than 5 minutes, which effectively improves the measurement efficiency.

[0026] In at least one embodiment of the present application, S11 and S12 are a specific implementation of the above S1.

[0027] S11: Prepare standard solutions with water hardness of 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L respectively, and adjust the pH to below 6.00 with hydrochloric acid so that calcium and magnesium exist in ionic form rather than colloidal form.

[0028] Water hardness as CaCO3.

[0029] Table 1 Calibration curve for low concentration measurements.

[0030] step Volume of standard solution added (mL) Concentration (mg / L) 1 0.1 1 2 0.2 2 3 0.5 5 4 1.0 10

[0031] S12: Add the corresponding volume of 1000mg / L water hardness standard solution, record the stable potential mV after each addition, and draw a standard curve on the coordinate paper with the potential value as the ordinate and the concentration as the abscissa, with the coordinate origin (0,0) and the measured value of the standard solution as the two points.

[0032] In at least one embodiment of the present application, S21 and S22 are a specific implementation of the above-mentioned S2.

[0033] S21: Measure 100 mL of the desalination water sample to be tested into a clean beaker and adjust the pH to below 6.00.

[0034] S22: Connect the water hardness composite electrode 10 and the ion meter 20, measure the potential value of the water quality sample A of the seawater desalination project to be tested, find the concentration (mg / L) corresponding to the potential value on the coordinate paper, and directly read the result as the hardness concentration in the water sample.

[0035] For example, the connection between the water hardness composite electrode 10 and the ion meter 20 is as follows: Figure 2 The water hardness composite electrode 10 converts the chemical signal into an electrical signal, and the ion meter 20 converts the electrical signal into a digital signal, so that the result can be directly read on the ion meter 20 as the hardness concentration in the water sample.

[0036] In at least one embodiment of the present application, the water hardness composite electrode is used as an online meter. In this way, the water hardness composite electrode can be used to obtain the water hardness of the seawater desalination project in real time, so as to timely control the hardness of the inlet and outlet water, and avoid blockages such as reverse osmosis membranes and pipelines caused by untimely water quality control.

[0037] In at least one embodiment of the present application, Figure 3 As shown, the water hardness composite electrode 10 includes an electrode cap 1, a cable 2, a filling hole 3, an electrode shell 4, a reference cell 5, an electrode interior 6 and a sensitive component 7. The electrode cap 1 is sleeved on the outside of the cable 2, and the cable 2 is connected to the electrode interior 6. The electrode interior 6 is connected to the sensitive component 7. The electrode interior 6 is arranged inside the electrode shell 4. The reference cell 5 is arranged in the gap between the electrode interior 6 and the electrode shell 4. The filling hole 3 is arranged on the electrode shell 4. The reference solution is added to the reference cell 5 through the filling hole 3. When the water hardness composite electrode is inserted into the water quality sample of the seawater desalination project to be tested, the electrode shell 4 and the sensitive component 7 in the water hardness composite electrode 10 are in direct contact with the water quality sample of the seawater desalination project to be tested.

[0038] It should be noted that the combination of the various technical features in the embodiments of the present application is not limited to the combination described in the embodiments of the present application or the combination described in the specific embodiments, and all technical features described in the present application can be freely combined or combined in any way unless there is a contradiction between them.

[0039] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the term "comprising" only indicates that the steps and elements that have been clearly identified are included, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0040] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for measuring water hardness in a seawater desalination project, characterized in that: include: Use standard solutions with different calcium and magnesium ion concentrations to calibrate the electrode to obtain standard curves with different concentration ranges. The potential value is the ordinate and the concentration is the abscissa in the standard curve. Insert the calibrated water hardness composite electrode into the water quality sample of the seawater desalination project to be tested, and calculate the hardness concentration of the water quality sample of the seawater desalination project to be tested through the potential value.

2. The measuring method according to claim 1, characterized in that: The electrode was calibrated using standard solutions of different calcium and magnesium ion concentrations to obtain standard curves in different concentration ranges, including: Prepare standard solutions with water hardness of 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L respectively, and use hydrochloric acid to adjust the pH to below 6.00 so that calcium and magnesium exist in ionic form rather than colloidal form; Add the corresponding volume of 1000 mg / L water hardness standard solution, record the stable potential after each addition, and draw a standard curve on the coordinate paper with the potential value as the ordinate and the concentration as the abscissa, with the coordinate origin and the measured value of the standard solution as the two points.

3. The measuring method according to claim 1, characterized in that: Insert the calibrated water hardness composite electrode into the water sample of the seawater desalination project to be tested, and calculate the hardness concentration of the water sample of the seawater desalination project to be tested through the potential value, including: Measure 100 mL of the desalination water sample to be tested into a clean beaker and adjust the pH to below 6.00; Connect the water hardness composite electrode and the ion meter, measure the potential value of the water quality sample of the seawater desalination project to be tested, find the concentration corresponding to the potential value on the coordinate paper, and directly read the result as the hardness concentration in the water sample.

4. The measuring method according to claim 1, characterized in that: The water hardness composite electrode is used as an online meter.

5. The measuring method according to any one of claims 1 to 4, characterized in that: The water hardness composite electrode includes an electrode cap, a cable, a filling hole, an electrode shell, a reference cell, an electrode interior and a sensitive component. The electrode cap is sleeved on the outside of the cable, the cable is connected to the electrode interior, the electrode interior and the sensitive component are connected, the electrode interior is arranged inside the electrode shell, the reference cell is arranged in the gap between the electrode interior and the electrode shell, the filling hole is arranged on the electrode shell, and the reference solution is added to the reference cell through the filling hole. When the water hardness composite electrode is inserted into the water quality sample of the seawater desalination project to be tested, the electrode shell and the sensitive component in the water hardness composite electrode are in direct contact with the water quality sample of the seawater desalination project to be tested.

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