Method and device for measuring purity of seawater desalination medicine

Abstract

The invention provides a method and a device for measuring the purity of a medicine for seawater desalination, and the method comprises the following steps: titrating a sodium hypochlorite sample by using a first reducing agent, detecting the change of a platinum electrode in the process, reading the consumption of the first reducing agent when the sodium hypochlorite sample is in redox equilibrium, and calculating the concentration of the first reducing agent; calculating in combination with a formula I to obtain the available chlorine concentration in the sodium hypochlorite sample; titrating the sodium hydrogen sulfite sample by using a second reducing agent, detecting the change of the platinum electrode in the process, reading the consumption of the second reducing agent when the sodium hydrogen sulfite sample is in redox equilibrium, and calculating by combining a formula II to obtain the mass fraction of sulfur dioxide in the sodium hydrogen sulfite sample. According to the present invention, by using the redox titration principle, the mark of the titration end point is accurately set and identified so as to solve the problems of poor detection result accuracy, high reagent consumption, low detection efficiency and tedious operation process of the existing manual titration analysis method.

Description

Technical Field

[0001] The present application belongs to the technical field of purity measurement of medicines used in seawater desalination, and specifically relates to a method and a device for measuring the purity of medicines used in seawater desalination. Background Art

[0002] The concentration of various chemicals in the desalination plant is particularly important for system operation because they play a vital role in the desalination process and subsequent treatment. For example, sodium hypochlorite is used to inhibit the growth of marine organisms on the inlet pipes and reverse osmosis membranes, hydrochloric acid and sodium hydroxide are used for pH adjustment, and sodium bisulfite is used for dechlorination. Inaccurate concentrations will affect the execution of the process and the quality of the water.

[0003] However, the manual titration method currently used has certain inaccuracies when measuring the concentration of these reagents. The manual titration process is not only error-prone, but also time-consuming. Its results are affected by factors such as titration technology, purity of titrants, and color recognition. As a result, the measurement results may be biased and it is difficult to obtain accurate results. Summary of the invention

[0004] In view of this, the embodiments of the present application are committed to providing a method and a device for measuring the purity of drugs used in seawater desalination. By utilizing the principle of redox titration, the mark of the titration end point is accurately set and identified to solve the problems of relatively poor detection result accuracy, high reagent consumption, low detection efficiency, and cumbersome operation process existing in the existing manual titration analysis method.

[0005] The first aspect of the present application provides a method for measuring the purity of seawater desalination drugs, the method comprising:

[0006] The sodium hypochlorite sample is titrated with the first reducing agent, and the change of the platinum electrode is detected during the process. When the sodium hypochlorite sample is in redox equilibrium, the consumption of the first reducing agent is read, and the effective chlorine concentration in the sodium hypochlorite sample is obtained by combining the formula 1.

[0007]

[0008] In formula 1, C1 represents the effective chlorine concentration in the sodium hypochlorite sample, C R1 represents the concentration of the first reducing agent, V1 represents the consumption of the first reducing agent, and m1 represents the mass of the sodium hypochlorite sample;

[0009] The sodium bisulfite sample is titrated with the second reducing agent, and the changes of the platinum electrode are detected during the process. When the sodium bisulfite sample is in redox equilibrium, the consumption of the second reducing agent is read, and the mass fraction of sulfur dioxide in the sodium bisulfite sample is obtained by combining the formula 2.

[0010]

[0011] In formula 2, C2 represents the mass fraction of sulfur dioxide; C R2 represents the concentration of the second reducing agent; V2 represents the consumption of the second reducing agent; m2 represents the mass of the sodium bisulfite sample.

[0012] In a specific embodiment of the present application, the method for measuring the purity of the seawater desalination drug further includes:

[0013] Use sodium hydroxide to titrate the hydrochloric acid sample, and use the pH electrode to detect the pH value change during this process. When the hydrochloric acid sample electrode potential jump point appears, read the sodium hydroxide consumption, and calculate the concentration of the hydrochloric acid sample by combining formula three.

[0014]

[0015] In formula 3, C3 represents the concentration of the hydrochloric acid sample, C R3 represents the concentration of sodium hydroxide, V3 represents the consumption of sodium hydroxide, and m3 represents the mass of hydrochloric acid sample;

[0016] Use hydrochloric acid to titrate the sodium hydroxide sample, and use the pH electrode to detect the pH value change during this process. When the electrode potential of the sodium hydroxide sample crosses the point, read the hydrochloric acid consumption, and calculate the concentration of the sodium hydroxide sample by combining formula 4.

[0017]

[0018] In formula 4, C4 represents the concentration of the sodium hydroxide sample; C R4 represents the concentration of hydrochloric acid; V4 represents the consumption of hydrochloric acid; m4 represents the mass of sodium hydroxide sample.

[0019] In a specific embodiment of the present application, the sodium hypochlorite sample is titrated with the first reducing agent, and the change of the platinum electrode is detected during the process. When the sodium hypochlorite sample is in redox equilibrium, the first reducing agent consumption is read, and the effective chlorine concentration in the sodium hypochlorite sample is obtained by calculation in combination with formula 1, including:

[0020] Combined with formula 5, the mass of the sodium hypochlorite sample is calculated.

[0021]

[0022] In formula 5, m1 represents the mass of sodium hypochlorite sample, E max Indicates the maximum redox potential that the electrode can measure, C 10 Indicates the estimated concentration of sodium hypochlorite;

[0023] Select sodium thiosulfate as the first reducing agent, and calculate the first reducing agent concentration C by combining formula 6: R1 ,

[0024]

[0025] Prepare 0.1 mol / L sodium thiosulfate pentahydrate solution;

[0026] Weigh 0.18g of standard potassium dichromate dried to constant weight at 105℃±2℃, place in an iodine volumetric flask, dissolve in 25mL of water, add 2g of potassium iodide and 20mL of 20% sulfuric acid solution, shake well, and place in a dark place for 10min. Add 150mL of water, and titrate with sodium thiosulfate pentahydrate standard solution until the solution turns light yellow. Add 2mL of 1% starch indicator and continue to titrate until the solution turns from blue to bright green. At the same time, perform a blank test and calculate the concentration of the first reducing agent using formula 7.

[0027]

[0028] In formula 7, G represents the mass of potassium dichromate; V 10 Indicates the volume of sodium thiosulfate solution consumed during titration; V 20 represents the volume of sodium thiosulfate solution consumed in titrating the blank solution; 0.04903 represents the molar mass of potassium dichromate in grams equivalent to 1.00 mL of sodium thiosulfate standard solution, in g / mmol;

[0029] According to Formula 5 and Formula 6, weigh 0.3g of sodium hypochlorite sample in the experimental container, add 10mL of 100g / L potassium iodide and 10mL of sulfuric acid solution, and then add water to 70ml. After standing in a dark place for 5 minutes, place the experimental container on the titration table, move the electrode and the titration head down and immerse them below the liquid surface, call the titration method that has been set in the measuring device, enter the sample weight, and after the titration is completed, the potentiometric titrator host of the measuring device will automatically calculate the effective chlorine concentration in the sodium hypochlorite based on Formula 1. After the titration is completed, record the result.

[0030] In a specific embodiment of the present application, the sodium bisulfite sample is titrated with the second reducing agent, and the change of the platinum electrode is detected during the process. When the sodium bisulfite sample is in redox equilibrium, the consumption of the second reducing agent is read, and the mass fraction of sulfur dioxide in the sodium bisulfite sample is obtained by combining formula 2, including:

[0031] Add 50mL of 0.1mol / L iodine standard solution to the experimental container, then add 5mL of acetic acid solution, and then add water to 70mL. After standing in the dark for 5 minutes, place the experimental container on the titration table, and lower the electrode and titration head to immerse below the liquid surface;

[0032] Call the titration method that has been set in the measuring device. After the blank titration is completed, weigh 0.2000g of solid sodium bisulfite directly in the experimental container, add 50mL of 0.1mol / L iodine standard solution, then add 5mL of acetic acid solution, and then add water to 70mL. After standing in the dark for 5 minutes, place the experimental container on the titration table, move the platinum electrode and the titration head down to immerse below the liquid surface, and enter the sample weight;

[0033] After the titration is completed, the potentiometric titrator host of the measuring device automatically calculates the mass fraction of sulfur dioxide in the sodium bisulfite sample in combination with Formula 2, and the result is recorded after the titration is completed.

[0034] In a specific embodiment of the present application, the hydrochloric acid sample is titrated with sodium hydroxide, and the pH electrode is used to detect the pH value change during the process. When the hydrochloric acid sample electrode potential jump point appears, the sodium hydroxide consumption is read, and the concentration of the hydrochloric acid sample obtained by calculation in combination with formula three includes:

[0035] Accurately weigh 0.6g of hydrochloric acid sample;

[0036] Sodium hydroxide was selected as the titrant, and 20 mL of titrant was added at a time using the automatic potentiometric titrator;

[0037] Before calibration, dry potassium hydrogen phthalate at 105℃±2℃ to constant weight. After cooling, weigh 1g potassium hydrogen phthalate and dissolve it in 50mL of freshly made high-purity water. Shake well. Add 2 drops of 1% phenolphthalein indicator and titrate the solution with sodium hydroxide standard solution until it turns pink and keep it for 30s. Perform a blank test at the same time.

[0038] Combined with formula 8, the sodium hydroxide concentration is calculated.

[0039]

[0040] In formula 8, G1 represents the weight of potassium hydrogen phthalate, V 30 Indicates the volume of sodium hydroxide solution consumed in titrating potassium hydrogen phthalate solution, V 40 represents the volume of sodium hydroxide solution consumed in titrating the blank solution, and 0.2042 represents the molar mass of potassium hydrogen phthalate;

[0041] Weigh 0.6g of sample directly in the experimental container and add water to 70mL. Place the experimental container on the titration table, and move the electrode and titration head down to immerse below the liquid surface. Call the titration method that has been set in the measuring device, enter the sample weight, and after the titration is completed, the potentiometric titrator host of the measuring device will automatically calculate the hydrochloric acid content in the sample based on formula 3, and record the result after the titration is completed.

[0042] In a specific embodiment of the present application, hydrochloric acid is used to titrate the sodium hydroxide sample, and a pH electrode is used to detect the pH value change during the process. When the electrode potential of the sodium hydroxide sample crosses a point, the hydrochloric acid consumption is read, and the concentration of the sodium hydroxide sample is obtained by combining formula 4, including:

[0043] Accurately weigh 0.2g of sodium hydroxide sample;

[0044] Select hydrochloric acid as the titrant, and add 20 mL of hydrochloric acid at a time using the automatic potentiometric titrator;

[0045] Before calibration, dry anhydrous sodium carbonate at 105℃±2℃ to constant weight. After cooling, weigh 0.3g (accurate to 0.1mg) in 50mL water, add 10 drops of bromocresol green-methyl red indicator, and titrate the solution from green to dark red with hydrochloric acid standard solution. Boil for 2 minutes. After cooling, continue to titrate until dark red. Perform a blank test at the same time;

[0046] Combined with formula 9, the concentration of hydrochloric acid is calculated.

[0047]

[0048] In formula 9, G2 represents the weight of anhydrous sodium carbonate; V 50 Indicates the volume of hydrochloric acid solution consumed in titration; V 60 represents the volume of hydrochloric acid solution consumed in titrating the blank solution; 0.05299 represents the molar mass of sodium carbonate;

[0049] Weigh 0.5g of sample directly in the experimental container, add water to about 70mL, place the experimental container on the titration table, move the pH electrode and the titration head down and immerse them below the liquid surface, call the titration method that has been set in the measuring device, input the sample weight, and after the titration is completed, the potentiometric titrator host of the measuring device will automatically calculate the sodium hydroxide content in the sample based on formula 4, and record the result after the titration is completed.

[0050] The second aspect of the present application provides a device for measuring the purity of drugs used in seawater desalination, which includes a reservoir, a burette, a potentiometric titrator host, an electrode, an experimental container, an agitator and a liquid adding tube. The reservoir is used to store titration reagents. The burette is used to accurately contain and add titrants. The potentiometric titrator host is used to control the titration experiment and process data to finally display the results. The electrode is used to respond to real-time potential changes to determine the titration end point. The experimental container is used to titrate the reaction container. The liquid adding tube is used to accurately add a pipeline for the titrant. The burette is connected between the reservoir and the potentiometric titrator host. One end of the electrode is connected to the potentiometric titrator host, and the other end of the electrode extends into the experimental container. One end of the agitator is connected to the potentiometric titrator host, and the other end of the agitator extends into the experimental container. One end of the liquid adding tube is connected to the burette, and the other end of the liquid adding tube extends into the experimental container.

[0051] The beneficial effect of the technical solution of the present application is that: the traditional method of manually judging the color of the titration endpoint is abandoned, and the indicator change is no longer used as the endpoint. The principle of redox titration is used to accurately set and identify the sign of the titration endpoint. The redox property (ORP value) of the sample is directly measured by using a platinum electrode, and the titration endpoint is directly judged without adding an indicator, avoiding manual judgment by color, thereby directly isolating the errors and time loss caused by manual judgment and excessive addition of reagents. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Shown is a flow chart of a method for measuring the purity of seawater desalination drugs provided in one embodiment of the present application.

[0053] Figure 2 Shown is a titration curve diagram provided in one embodiment of the present application.

[0054] Figure 3 Shown is a schematic structural diagram of a device for measuring the purity of seawater desalination drugs provided in one embodiment of the present application. DETAILED DESCRIPTION

[0055] 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.

[0056] At least one embodiment of the present application provides a method for measuring the purity of seawater desalination drugs, referring to Figure 1 The method for measuring the purity of seawater desalination drugs includes the following steps S1 and S2.

[0057] S1: Use the first reducing agent to titrate the sodium hypochlorite sample, and detect the change of the platinum electrode in the process. When the sodium hypochlorite sample is in redox equilibrium, read the consumption of the first reducing agent, and calculate with formula 1 to obtain the effective chlorine concentration in the sodium hypochlorite sample.

[0058]

[0059] In formula 1, C1 represents the effective chlorine concentration in the sodium hypochlorite sample; C R1 represents the concentration of the first reducing agent; V1 represents the consumption of the first reducing agent; m1 represents the mass of the sodium hypochlorite sample.

[0060] It should be noted that the sodium hypochlorite sample can also be called a sodium hypochlorite salt solution sample.

[0061] S2: Use the second reducing agent to titrate the sodium bisulfite sample, and detect the changes in the platinum electrode during this process. When the sodium bisulfite sample is in redox equilibrium, read the second reducing agent consumption, and calculate with formula 2 to obtain the mass fraction of sulfur dioxide in the sodium bisulfite sample.

[0062]

[0063] In formula 2, C2 represents the mass fraction of sulfur dioxide; C R2 represents the concentration of the second reducing agent; V2 represents the consumption of the second reducing agent; m2 represents the mass of the sodium bisulfite sample.

[0064] For example, the units of C1 and C2 are %, C R1 and C R2 The unit of is mol / L, the unit of V1 and V2 is mL, and the unit of m1 and m2 is g.

[0065] It should be noted that the platinum electrode is an electrode capable of measuring oxidation-reduction potential (ORP).

[0066] It should be understood that the principle of the traditional method of sodium hypochlorite is: adding an excess of potassium iodide, a reducing agent, to sodium hypochlorite to make the sample reductive, and at the same time, due to oxidation, potassium iodide is converted into elemental iodine, and a starch indicator is added to make the sample appear blue. Sodium thiosulfate is used to titrate the oxidizing sample to convert elemental iodine into iodide ions, thereby causing the indicator color to disappear. The principle of the traditional method of sodium bisulfite is: adding acetic acid to make the solution weakly acidic, adding an excess of oxidizing agent iodine to sodium bisulfite, and adding a starch indicator to make the sample appear blue. Sodium thiosulfate is used to titrate the excess iodine to convert elemental iodine into iodide ions, thereby causing the indicator color to disappear.

[0067] According to the technical solution provided in the embodiment of the present application, the traditional method of manually judging the color of the titration endpoint is abandoned, and the indicator change is no longer used as the endpoint. The principle of redox titration is used to accurately set and identify the sign of the titration endpoint. The redox property (ORP value) of the sample is directly measured by using a platinum electrode, and the titration endpoint is directly judged without adding an indicator, avoiding manual judgment by color, thereby directly isolating the errors and time loss caused by manual judgment and excessive addition of reagents.

[0068] In the present application, potentiometric titration is used for measurement. As a more precise and modern measuring method, potentiometric titration can accurately measure the concentration of these reagents. By measuring the change of potential during titration, the titration end point can be accurately determined without manual judgment, so as to obtain a more accurate concentration result. In addition, potentiometric titration is not affected by human factors, and its measurement repeatability is good, which can greatly improve the accuracy and repeatability of concentration measurement. In addition, potentiometric titration is used to measure the concentration of chemicals in seawater desalination to achieve more accurate and efficient concentration measurement of sodium hypochlorite, hydrochloric acid, sodium hydroxide and sodium bisulfite, so as to improve the effect and quality of seawater desalination, and also contribute to environmental protection and energy saving, and will also be conducive to the optimization of process control, and bring substantial improvement to long-term operation and economic benefits.

[0069] In at least one embodiment of the present application, the method for measuring the purity of drugs for seawater desalination further includes the following steps S3 and S4.

[0070] S3: Use sodium hydroxide to titrate the hydrochloric acid sample, and use the pH electrode to detect the pH value change during this process. When the hydrochloric acid sample electrode potential jump point appears, read the sodium hydroxide consumption and calculate it with formula three to obtain the concentration of the hydrochloric acid sample.

[0071]

[0072] In formula 3, C3 represents the concentration of the hydrochloric acid sample; C R3 represents the concentration of sodium hydroxide; V3 represents the consumption of sodium hydroxide; m3 represents the mass of hydrochloric acid sample.

[0073] S4: Use hydrochloric acid to titrate the sodium hydroxide sample, and use the pH electrode to detect the pH value change during this process. When the electrode potential jump point of the sodium hydroxide sample appears, read the hydrochloric acid consumption and calculate the concentration of the sodium hydroxide sample by combining with formula 4.

[0074]

[0075] In formula 4, C4 represents the concentration of the sodium hydroxide sample; C R4 represents the concentration of hydrochloric acid; V4 represents the consumption of hydrochloric acid; m4 represents the mass of sodium hydroxide sample.

[0076] It should be understood that the principle of the traditional method of hydrochloric acid is: using the principle of acid-base titration, using sodium hydroxide as the standard solution for direct titration, using bromocresol green as the indicator, and using sodium hydroxide standard solution to drip until the solution changes from yellow to blue as the end point. The principle of the traditional method of sodium hydroxide is: using the principle of acid-base titration, using hydrochloric acid as the standard solution for direct titration, using 1% phenolphthalein solution as the indicator, and using hydrochloric acid standard solution to drip until the solution changes from red to colorless as the end point.

[0077] According to the technical solution provided in the embodiment of the present application, the traditional method of manually judging the color of the titration endpoint is abandoned, and the indicator change is no longer used as the endpoint. The principle of acid-base titration is used to accurately set and identify the sign of the titration endpoint. The pH electrode is used to directly judge the titration endpoint, avoiding manual judgment by color, thereby directly isolating the errors and time loss caused by manual judgment and excessive addition of reagents.

[0078] In addition, the measurement method provided in the embodiment of the present application uses a platinum electrode and a pH electrode, which has high accuracy, good repeatability, simplified operation steps, and significantly reduced analysis time. Furthermore, it has the feasibility of online transformation, further improving the chemical supervision ability, high degree of automation, high accuracy of test results, high analysis efficiency, low reagent consumption, and simple operation. After the implementation of this technology, efficiency and stability are improved, and the amount of chemicals used is reduced. Fully save time, the average analysis time for a sample is reduced from 20 minutes to 10 minutes, and the time is shortened by 50%; improve measurement stability, reduce the relative deviation of two parallel measurements, from 2% to 0.5%, and the stability improvement rate reaches 75%; reduce the amount of chemicals used, no longer use potassium iodide and starch, and reduce management and operating costs.

[0079] In at least one embodiment of the present application, S11 to S15 are a specific implementation of S1 above. S11, calculate the mass of the sodium hypochlorite sample in combination with formula 5.

[0080]

[0081] In formula 5, m1 represents the mass of sodium hypochlorite sample; E max Indicates the maximum redox potential that the electrode can measure; C 10 Indicates the estimated concentration of sodium hypochlorite.

[0082] It should be noted that the mass of the sodium hypochlorite sample is the weighed amount of the sodium hypochlorite sample. max The unit is mV. The first reducing agent is a titrant.

[0083] For example, the maximum oxidation potential measurement range of the currently common platinum electrode is between (-1000-2000) mV. According to measured data, when the concentration of sodium hypochlorite is 10% and diluted to 50 mL, the sample volume is 0.2000g-0.4000g, and the above formula 5 can be used for conversion.

[0084] S12: Select sodium thiosulfate as the first reducing agent, and calculate the first reducing agent concentration C by combining formula 6: R1 .

[0085]

[0086] For example, a relatively pure, relatively stable, easy-to-obtain and easy-to-prepare reducing agent is used. According to the relevant standards of the titration work, sodium thiosulfate is selected as the first reducing agent. The concentration setting needs to be carried out according to the estimated concentration of sodium hypochlorite. At the same time, the consumption of the first reducing agent and the mass of the sodium hypochlorite sample are taken into account, so that the consumption of the first reducing agent is about 10 mL and the sample mass is between (0.5-1.0) g. Combined with Formula 6, the concentration of the first reducing agent required for different sample concentrations can be calculated.

[0087] S13: prepare 0.1 mol / L sodium thiosulfate pentahydrate solution.

[0088] For example, weigh 26g of sodium thiosulfate pentahydrate (Na2S2O3·5H2O) or 16g of anhydrous sodium thiosulfate, add 0.2g of anhydrous sodium carbonate, dissolve in 1L of water, slowly boil for 10 minutes, and cool. Store in a brown reagent bottle with a ground stopper and set aside for two weeks. If there is precipitation, filter it with a filter (filtration accuracy of 0.45μm).

[0089] S14: Weigh 0.18g of the standard potassium dichromate dried to constant weight at 105℃±2℃, place it in an iodine volumetric flask, dissolve it in 25mL of water, add 2g of potassium iodide and 20mL of 20% sulfuric acid solution, shake well, and place it in a dark place for 10min. Add 150mL of water, and titrate the solution with sodium thiosulfate pentahydrate standard solution until it turns light yellow. Add 2mL of 1% starch indicator and continue to titrate the solution from blue to bright green. At the same time, perform a blank test and calculate the first reducing agent concentration in combination with formula 7.

[0090]

[0091] In formula 7, G represents the mass of potassium dichromate; V 10 Indicates the volume of sodium thiosulfate solution consumed during titration; V 20 represents the volume of sodium thiosulfate solution consumed in titrating the blank solution; 0.04903 represents the molar mass of potassium dichromate in grams equivalent to 1.00 mL of sodium thiosulfate standard solution, in g / mmol.

[0092] For example, G is in g, V is in 10 and V 20 The unit of is mL, and the unit of 0.04903 is g / mmol. The concentration of the sodium thiosulfate standard solution can be C(Na2S2O3)=0.1 mol / L. The standard potassium dichromate 0.18g can be weighed accurately to 0.1mg.

[0093] S15: According to Formula 5 and Formula 6, weigh 0.3g of sodium hypochlorite sample in the experimental container, add 10mL of 100g / L potassium iodide and 10mL of sulfuric acid solution, and then add water to 70ml. After standing in a dark place for 5 minutes, place the experimental container on the titration table, move the electrode and the titration head down and immerse them below the liquid surface, call the titration method that has been set in the measuring device, input the sample weight, and after the titration is completed, the potentiometric titrator host of the measuring device automatically calculates the effective chlorine concentration in the sodium hypochlorite in combination with Formula 1. After the titration is completed, record the result.

[0094] It should be noted that 0.3 g of sodium hypochlorite sample can be weighed accurately to 0.0001 g, assuming the sample concentration is 10%. 10 mL of sulfuric acid solution can be weighed assuming the sample concentration is 3%.

[0095] For example, refer to Figure 2 , Figure 2 U represents potential, ERC represents equivalence point recognition coefficient, Figure 2 1 indicates the potential jump point corresponding to the titration endpoint. Figure 2 2 in the figure indicates the electrode potential jump value corresponding to the titration endpoint.

[0096] The above step S11 is for selecting the sample amount in the determination of the content of the sodium hypochlorite solution, the above step S12 is for selecting the type and concentration of the titrant in the determination of the content of the sodium hypochlorite solution, the above step S13 is for calibrating the titrant in the determination of the content of the sodium hypochlorite solution, and the above step S15 is for sample titration in the determination of the content of the sodium hypochlorite solution.

[0097] The selection of sample amount, selection of titrant type and concentration, titrant calibration and sample titration in the determination of sodium bisulfite content can all refer to the corresponding steps in the determination of the sodium hypochlorite solution content involved in the above steps S11 to S15, with the only difference being that the sampling amount is 0.2000 g of solid sodium bisulfite.

[0098] In at least one embodiment of the present application, S21 to S23 are a specific implementation of the above S2.

[0099] S21: Add 50 mL of 0.1 mol / L iodine standard solution to the experimental container, then add 5 mL of acetic acid solution, and then add water to 70 mL. After standing in the dark for 5 minutes, place the experimental container on the titration table, and move the electrode and titration head down to immerse below the liquid surface.

[0100] S22: Call the titration method that has been set in the measuring device. After the blank titration is completed, weigh 0.2000g of solid sodium bisulfite directly in the experimental container, add 50mL of 0.1mol / L iodine standard solution, then add 5mL of acetic acid solution, and then add water to 70mL. After standing in the dark for 5 minutes, place the experimental container on the titration table, move the platinum electrode and the titration head down to immerse below the liquid surface, and enter the sample weight.

[0101] 0.2000g of solid sodium bisulfite can be weighed accurately to 0.0001g, assuming a sample concentration of 10%.

[0102] S23: After the titration is completed, the potentiometric titrator host of the measuring device automatically calculates the mass fraction of sulfur dioxide in the sodium bisulfite sample in combination with Formula 2, and the result is recorded after the titration is completed.

[0103] In at least one embodiment of the present application, S31 to S35 are a specific implementation of the above S3.

[0104] S31: Accurately weigh 0.6 g of hydrochloric acid sample.

[0105] For example, a hydrochloric acid sample can be weighed accurately to 0.0001 g. Based on a sample concentration of 30%, the hydrochloric acid sample is approximately 0.005 mol.

[0106] S32: Sodium hydroxide is selected as the titrant, and 20 mL of titrant is added at a time using the automatic potentiometric titrator.

[0107] For example, the hydrochloric acid sample is about 0.005 mol, so the sodium hydroxide concentration can be selected as 0.5 mol / L.

[0108] S33: Before calibration, dry potassium hydrogen phthalate at 105℃±2℃ to constant weight. After cooling, weigh 1g potassium hydrogen phthalate and dissolve it in 50mL of freshly prepared high-purity water. Shake well. Add 2 drops of 1% phenolphthalein indicator and titrate the solution with sodium hydroxide standard solution until it turns pink and keep it for 30s. Perform a blank test at the same time.

[0109] S34: The sodium hydroxide concentration is calculated by combining formula 8.

[0110]

[0111] In formula 8, G1 represents the weight of potassium hydrogen phthalate; V 30 Indicates the volume of sodium hydroxide solution consumed in titrating potassium hydrogen phthalate solution; V 40 represents the volume of sodium hydroxide solution consumed in titrating the blank solution; 0.2042 represents the molar mass of potassium hydrogen phthalate.

[0112] It should be noted that 1g of potassium hydrogen phthalate can be weighed to 0.1mg. Sodium hydroxide concentration C R3 That is, the molar concentration of the sodium hydroxide standard solution. The unit of G can be g. 30 and V 40 The unit of can be mL. The unit of 0.2042 can be g / mmol.

[0113] S35: Weigh 0.6g of sample directly in the experimental container and add water to 70mL. Place the experimental container on the titration table, and move the electrode and titration head down to immerse below the liquid surface. Call the titration method that has been set in the measuring device, enter the sample weight, and after the titration is completed, the potentiometric titrator host of the measuring device will automatically calculate the hydrochloric acid content in the sample based on formula 3, and record the result after the titration is completed.

[0114] The hydrochloric acid sample can be weighed accurately to 0.0001g, based on a sample concentration of 30%.

[0115] In at least one embodiment of the present application, S41 to S45 are a specific implementation of the above S4.

[0116] S41: Accurately weigh 0.2 g of sodium hydroxide sample.

[0117] For example, accurate to 0.0001 g, assuming that the concentration of the sodium hydroxide sample is 30%, the sodium hydroxide is approximately 0.004 mol.

[0118] S42: Select hydrochloric acid as the titrant and add 20 mL of hydrochloric acid at a time using the automatic potentiometric titrator.

[0119] For example, the hydrochloric acid sample is about 0.004 mol, so the hydrochloric acid concentration is selected to be 0.5 mol / L.

[0120] S43: Before calibration, dry anhydrous sodium carbonate at 105℃±2℃ to constant weight. After cooling, weigh 0.3g (accurate to 0.1mg) in 50mL water, add 10 drops of bromocresol green-methyl red indicator, and titrate the solution from green to dark red with hydrochloric acid standard solution. Boil for 2 minutes. After cooling, continue to titrate until dark red. Perform a blank test at the same time.

[0121] S44: Calculate the concentration of hydrochloric acid using formula nine.

[0122]

[0123] In formula 9, G2 represents the weight of anhydrous sodium carbonate; V 50 Indicates the volume of hydrochloric acid solution consumed in titration; V 60 represents the volume of hydrochloric acid solution consumed in titrating the blank solution; 0.05299 represents the molar mass of sodium carbonate.

[0124] The unit of G2 may be g, and the unit of 0.05299 may be g / mmol. 50 and V 60 The unit can be mL. The concentration of hydrochloric acid can also be called the molar concentration of the hydrochloric acid standard solution. Sodium carbonate can be expressed as 1 / 2Na2CO3.

[0125] S45: Weigh 0.5g of sample directly in the experimental container and add water to about 70mL. Place the experimental container on the titration table, and move the pH electrode and titration head down to immerse below the liquid surface. Call the titration method that has been set in the measuring device, enter the sample weight, and after the titration is completed, the potentiometric titrator host of the measuring device will automatically calculate the sodium hydroxide content in the sample in combination with formula 4. After the titration is completed, record the result.

[0126] It should be noted that 0.5 g of sample can be weighed accurately to 0.0001 g, assuming the sample concentration is 30%.

[0127] At least one embodiment of the present application also provides a device for measuring the purity of seawater desalination drugs, referring to Figure 3 The device for measuring the purity of seawater desalination medicine comprises a liquid reservoir 1, a burette 2, a potentiometric titrator host 3, an electrode 4, an experimental container 5, an agitator 6 and a liquid adding tube 7. The liquid reservoir 1 is used to store titration reagents. The burette 2 is used to accurately contain and add titrants. The potentiometric titrator host 3 is used to control the titration experiment and process data to finally display the results. The electrode 4 is used to respond to real-time potential changes to determine the titration end point. The experimental container 5 is used to titrate the reaction container. The liquid adding tube 7 is used to accurately add a pipeline for the titrant. The burette 2 is connected between the liquid reservoir 1 and the potentiometric titrator host 3. One end of the electrode 4 is connected to the potentiometric titrator host 3, and the other end of the electrode 4 extends into the experimental container 5. One end of the agitator 6 is connected to the potentiometric titrator host 3, and the other end of the agitator 6 extends into the experimental container 5. One end of the liquid adding tube 7 is connected to the burette 2, and the other end of the liquid adding tube 7 extends into the experimental container 5.

[0128] It should be noted that the burette 2 can ensure the accurate volume of the titrant used. The electrode 4 includes a platinum electrode and a pH electrode. The platinum electrode is used to respond to real-time redox potential changes. The pH electrode is used to respond to pH potential changes. The experimental container 5 can use a beaker or a titration cup. The agitator 6 is used to ensure that the titration process is fully mixed and uniform, ensuring that the solution to be tested and the titrant can react quickly and fully.

[0129] The technical solutions provided in all the above embodiments of the present application reduce manual operations and adopt a standardized method that can directly determine the titration results, so as to make the measurement results more stable and quick, and can quickly and accurately analyze the concentrations of available chlorine, hydrochloric acid, sodium hydroxide and sodium bisulfite in the sodium hypochlorite salt solution.

[0130] 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.

[0131] 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.

[0132] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0133] 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 the purity of seawater desalination drugs, characterized in that: include: The sodium hypochlorite sample is titrated with the first reducing agent, and the change of the platinum electrode is detected during the process. When the sodium hypochlorite sample is in redox equilibrium, the consumption of the first reducing agent is read, and the effective chlorine concentration in the sodium hypochlorite sample is obtained by combining the formula 1. In formula 1, C1 represents the effective chlorine concentration in the sodium hypochlorite sample, C R1 represents the concentration of the first reducing agent, V1 represents the consumption of the first reducing agent, and m1 represents the mass of the sodium hypochlorite sample; The sodium bisulfite sample is titrated with the second reducing agent, and the changes of the platinum electrode are detected during the process. When the sodium bisulfite sample is in redox equilibrium, the consumption of the second reducing agent is read, and the mass fraction of sulfur dioxide in the sodium bisulfite sample is obtained by combining the formula 2. In formula 2, C2 represents the mass fraction of sulfur dioxide; C R2 represents the concentration of the second reducing agent; V2 represents the consumption of the second reducing agent; m2 represents the mass of the sodium bisulfite sample.

2. The method for measuring the purity of seawater desalination drugs according to claim 1, characterized in that: Also includes: Use sodium hydroxide to titrate the hydrochloric acid sample, and use the pH electrode to detect the pH value change during this process. When the hydrochloric acid sample electrode potential jump point appears, read the sodium hydroxide consumption, and calculate the concentration of the hydrochloric acid sample by combining formula three. In formula 3, C3 represents the concentration of the hydrochloric acid sample, C R3 represents the concentration of sodium hydroxide, V3 represents the consumption of sodium hydroxide, and m3 represents the mass of hydrochloric acid sample; Use hydrochloric acid to titrate the sodium hydroxide sample, and use the pH electrode to detect the pH value change during this process. When the electrode potential of the sodium hydroxide sample crosses the point, read the hydrochloric acid consumption, and calculate the concentration of the sodium hydroxide sample by combining formula 4. In formula 4, C4 represents the concentration of the sodium hydroxide sample; C R4 represents the concentration of hydrochloric acid; V4 represents the consumption of hydrochloric acid; m4 represents the mass of sodium hydroxide sample.

3. The method for measuring the purity of seawater desalination drugs according to claim 1, characterized in that: The sodium hypochlorite sample is titrated with the first reducing agent, and the change of the platinum electrode is detected during the process. When the sodium hypochlorite sample is in redox equilibrium, the consumption of the first reducing agent is read, and the effective chlorine concentration in the sodium hypochlorite sample is obtained by combining with formula 1, including: Combined with formula 5, the mass of the sodium hypochlorite sample is calculated. In formula 5, m1 represents the mass of sodium hypochlorite sample, E max Indicates the maximum redox potential that the electrode can measure, C 10 Indicates the estimated concentration of sodium hypochlorite; Select sodium thiosulfate as the first reducing agent, and calculate the first reducing agent concentration C by combining formula 6: R1 , Prepare 0.1 mol / L sodium thiosulfate pentahydrate solution; Weigh 0.18g of standard potassium dichromate dried to constant weight at 105℃±2℃, place in an iodine volumetric flask, dissolve in 25mL of water, add 2g of potassium iodide and 20mL of 20% sulfuric acid solution, shake well, place in a dark place for 10min, add 150mL of water, and titrate with sodium thiosulfate pentahydrate standard solution until the solution turns light yellow. Add 2mL of 1% starch indicator and continue to titrate until the solution changes from blue to bright green. At the same time, perform a blank test and calculate the concentration of the first reducing agent in combination with formula 7. In formula 7, G represents the mass of potassium dichromate; V 10 Indicates the volume of sodium thiosulfate solution consumed during titration; V 20 represents the volume of sodium thiosulfate solution consumed in titrating the blank solution; 0.04903 represents the molar mass of potassium dichromate in grams equivalent to 1.00 mL of sodium thiosulfate standard solution, in g / mmol; According to Formula 5 and Formula 6, weigh 0.3g of sodium hypochlorite sample in the experimental container, add 10mL of 100g / L potassium iodide and 10mL of sulfuric acid solution, and then add water to 70ml. After standing in a dark place for 5 minutes, place the experimental container on the titration table, move the electrode and the titration head down and immerse them below the liquid surface, call the titration method that has been set in the measuring device, enter the sample weight, and after the titration is completed, the potentiometric titrator host of the measuring device will automatically calculate the effective chlorine concentration in the sodium hypochlorite based on Formula 1. After the titration is completed, record the result.

4. The method for measuring the purity of seawater desalination drugs according to claim 1, characterized in that: The sodium bisulfite sample is titrated with the second reducing agent, and the change of the platinum electrode is detected during the process. When the sodium bisulfite sample is in redox equilibrium, the consumption of the second reducing agent is read, and the mass fraction of sulfur dioxide in the sodium bisulfite sample is obtained by combining formula 2, including: Add 50 mL of 0.1 mol / L iodine standard solution to the experimental container, then add 5 mL of acetic acid solution, and then add water to 70 mL. After standing in a dark place for 5 minutes, place the experimental container on the titration table, and move the electrode and titration head down to immerse below the liquid surface; Call the titration method that has been set in the measuring device. After the blank titration is completed, weigh 0.2000g of solid sodium bisulfite directly in the experimental container, add 50mL of 0.1mol / L iodine standard solution, then add 5mL of acetic acid solution, and then add water to 70mL. After standing in the dark for 5 minutes, place the experimental container on the titration table, move the platinum electrode and the titration head down to immerse below the liquid surface, and input the sample weight; After the titration is completed, the potentiometric titrator host of the measuring device automatically calculates the mass fraction of sulfur dioxide in the sodium bisulfite sample in combination with Formula 2, and the result is recorded after the titration is completed.

5. The method for measuring the purity of seawater desalination drugs according to any one of claims 2 to 4, characterized in that: Use sodium hydroxide to titrate the hydrochloric acid sample, and use the pH electrode to detect the pH change during the process. When the hydrochloric acid sample electrode potential jump point appears, read the sodium hydroxide consumption. Combined with formula 3, the concentration of the hydrochloric acid sample is calculated as follows: Accurately weigh 0.6g of hydrochloric acid sample; Sodium hydroxide was selected as the titrant, and 20 mL of titrant was added at a time using the automatic potentiometric titrator; Before calibration, dry potassium hydrogen phthalate at 105℃±2℃ to constant weight. After cooling, weigh 1g potassium hydrogen phthalate and dissolve it in 50mL of freshly prepared high-purity water. Shake well, add 2 drops of 1% phenolphthalein indicator, and titrate the solution with sodium hydroxide standard solution until it turns pink. Keep it for 30s, and do a blank test at the same time. Combined with formula 8, the sodium hydroxide concentration is calculated. In formula 8, G1 represents the weight of potassium hydrogen phthalate, V 30 Indicates the volume of sodium hydroxide solution consumed in titrating potassium hydrogen phthalate solution, V 40 represents the volume of sodium hydroxide solution consumed in titrating the blank solution, and 0.2042 represents the molar mass of potassium hydrogen phthalate; Weigh 0.6g of sample directly in the experimental container, add water to 70mL, place the experimental container on the titration table, move the electrode and titration head down and immerse them below the liquid surface, call the titration method that has been set in the measuring device, input the sample weight, and after the titration is completed, the potentiometric titrator host of the measuring device will automatically calculate the hydrochloric acid content in the sample based on formula 3, and record the result after the titration is completed.

6. The method for measuring the purity of seawater desalination drugs according to any one of claims 2 to 4, characterized in that: Use hydrochloric acid to titrate the sodium hydroxide sample, and use the pH electrode to detect the pH value change during this process. When the electrode potential of the sodium hydroxide sample crosses the point, read the hydrochloric acid consumption, and calculate the concentration of the sodium hydroxide sample by combining formula 4, including: Accurately weigh 0.2g of sodium hydroxide sample; Select hydrochloric acid as the titrant, and add 20 mL of hydrochloric acid at a time using the automatic potentiometric titrator; Before calibration, dry anhydrous sodium carbonate at 105℃±2℃ to constant weight. After cooling, weigh 0.3g (accurate to 0.1mg) in 50mL water, add 10 drops of bromocresol green-methyl red indicator, and use hydrochloric acid standard solution to titrate the solution from green to dark red. Boil for 2 minutes, cool and continue to titrate until dark red. At the same time, perform a blank test; Combined with formula 9, the concentration of hydrochloric acid is calculated. In formula 9, G2 represents the weight of anhydrous sodium carbonate; V 50 Indicates the volume of hydrochloric acid solution consumed in titration; V 60 represents the volume of hydrochloric acid solution consumed in titrating the blank solution; 0.05299 represents the molar mass of sodium carbonate; Weigh 0.5g of sample directly in the experimental container, add water to about 70mL, place the experimental container on the titration table, move the pH electrode and the titration head down and immerse them below the liquid surface, call the titration method that has been set in the measuring device, input the sample weight, and after the titration is completed, the potentiometric titrator host of the measuring device will automatically calculate the sodium hydroxide content in the sample based on formula 4, and record the result after the titration is completed.

7. A device for measuring the purity of seawater desalination drugs, characterized in that: It includes a liquid reservoir, a burette, a potentiometric titrator host, electrodes, an experimental container, a stirrer and a liquid adding tube. The reservoir is used to store the titration reagent, the burette is used to accurately hold and add the titrant, the potentiometric titrator host is used to control the titration experiment and process the data to finally display the results, the electrode is used to respond to the real-time potential change to determine the titration endpoint, the experimental container is used to titrate the reaction container, and the dosing tube is used to accurately add the titrant pipeline. The burette is connected between the liquid reservoir and the potentiometric titrator host, one end of the electrode is connected to the potentiometric titrator host, and the other end of the electrode extends into the experimental container, one end of the stirrer is connected to the potentiometric titrator host, and the other end of the stirrer extends into the experimental container, one end of the liquid adding tube is connected to the burette, and the other end of the liquid adding tube extends into the experimental container.

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