Method and device for determining the sodium chlorate content of an industrial sodium hypochlorite solution

Abstract

The application provides a method and device for determining the content of sodium chlorate in industrial sodium hypochlorite solution, comprising the following steps: a. eliminating the interference of sodium hypochlorite: adding hydrogen peroxide to the industrial sodium hypochlorite solution to be measured, so that the hydrogen peroxide is excessive to destroy the sodium hypochlorite; b. neutralizing sodium hydroxide: using sulfuric acid solution to neutralize sodium hydroxide; c. reducing sodium chlorate: under an acidic environment, adding ferrous sulfate as a reducing agent to the treated solution to reduce sodium chlorate into chloride ions; d. titrating residual ferrous ions: using sodium diphenylamine sulfonate as an indicator, using 0.1 mol / L potassium dichromate standard titration solution to titrate the excessive ferrous ions until the solution color changes to purple and the titration end point is reached; e. calculating the content of sodium chlorate: according to the volume and concentration of the potassium dichromate standard solution consumed in titration, the mass concentration of sodium chlorate is calculated. The method and device for determining the content of sodium chlorate in industrial sodium hypochlorite solution provided by the application have the advantages that the determination result is more accurate and reliable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ADC foaming agent production, and particularly relates to a method and device for determining the content of sodium chlorate in industrial sodium hypochlorite solution. BACKGROUND

[0002] The current domestic ADC foaming agent production process is mainly urea oxidation method, which uses urea, chlorine and caustic soda as starting materials. Hydrazine hydrate is first prepared, and then hydrazine hydrate and urea are reacted in the presence of sulfuric acid to generate biurea. The biurea is oxidized by chlorine to obtain ADC foaming agent. After washing, centrifugation and drying, the finished product is obtained. In the preparation of hydrazine hydrate, sodium hypochlorite solution is first prepared by reacting chlorine and liquid caustic. The reaction of chlorine and liquid caustic will generate a side reaction to generate sodium chlorate. In addition, sodium chlorate is also unstable and will decompose to generate sodium chlorate. The sodium chlorate has a certain influence on the yield of biurea converted into ADC foaming agent in the chlorine oxidation biurea process. Therefore, it is necessary to monitor the content of sodium chlorate in industrial sodium hypochlorite. Although there are reports on the determination method of chlorate at home and abroad, the detection of sodium chlorate in sodium hypochlorite solution is rarely involved. SUMMARY

[0003] One object of the present application is to provide a method for determining the content of sodium chlorate in industrial sodium hypochlorite solution, so as to determine the content of sodium chlorate in industrial sodium hypochlorite solution.

[0004] To achieve the above object, the technical scheme adopted by the present application is as follows: a method for determining the content of sodium chlorate in industrial sodium hypochlorite solution is provided, comprising the following steps:

[0005] a. Eliminate the interference of sodium hypochlorite: add hydrogen peroxide to the industrial sodium hypochlorite solution to be measured, so that it is excessive, so as to destroy the sodium hypochlorite;

[0006] b. Neutralize sodium hydroxide: use sulfuric acid solution to neutralize sodium hydroxide in the sodium hypochlorite solution;

[0007] c. Reduce sodium chlorate: in an acidic environment, add ferrous sulfate as a reducing agent to the treated solution to reduce sodium chlorate to chloride ion;

[0008] d. Titrate the remaining ferrous ion: use sodium diphenylamine sulfonate as an indicator, and use 0.1 mol / L potassium dichromate standard titration solution to titrate the excess ferrous ion until the solution color changes to purple, reaching the titration end point;

[0009] e. Calculate the content of sodium chlorate: according to the volume and concentration of the potassium dichromate standard solution consumed in titration, the mass concentration of sodium chlorate is calculated.

[0010] In one embodiment, the amount of hydrogen peroxide added in step a is 0.5 mL, which completely destroys the sodium hypochlorite and is excessive.

[0011] In one embodiment, the concentration of the ferrous sulfate standard solution in step c is 0.1 mol / L, and the reduction reaction is carried out under the condition of heating and boiling.

[0012] In one embodiment, step d further comprises adding a phosphoric acid solution to the solution before titration to eliminate the interference of ferric ions and adjust the acidity of the solution.

[0013] Another object of the present application is to provide a device for measuring the content of sodium chlorate in industrial sodium hypochlorite solution, which is used to perform the method for measuring the content of sodium chlorate in industrial sodium hypochlorite solution according to any one of the above embodiments. The device for measuring the content of sodium chlorate in industrial sodium hypochlorite solution comprises:

[0014] A mounting frame;

[0015] A burette mounted on the mounting frame, the burette containing a titration solution, and the bottom of the burette being provided with a valve;

[0016] An Erlenmeyer flask connected to the mounting frame at the position of the mouth of the Erlenmeyer flask through a connecting part, the Erlenmeyer flask being located directly below the burette, and the Erlenmeyer flask containing a solution to be titrated;

[0017] The connecting part comprises a metal ring of an outer ring and a flexible pad of an inner ring, the flexible pad being arranged in the inner ring of the metal ring, the mouth of the Erlenmeyer flask being sleeved in the flexible pad, and the metal ring being fixed on the mounting frame so that the bottom of the Erlenmeyer flask can be shaken when the mouth of the Erlenmeyer flask is mounted on the mounting frame.

[0018] In one embodiment, an oscillation device is further included, which is arranged on the Erlenmeyer flask and comprises:

[0019] A mounting ring sleeved on the neck of the Erlenmeyer flask;

[0020] An electromagnet arranged on the mounting ring;

[0021] The metal ring is made of a ferromagnetic metal material.

[0022] In one embodiment, a control part is further included, which comprises:

[0023] A laser generator arranged at the bottom of the burette, and the light emitting direction of the laser generator being vertically downward;

[0024] A laser receiver in a planar shape and attached to the bottom of the Erlenmeyer flask; the laser receiver being electrically connected to the electromagnet.

[0025] In one embodiment, the valve is an electromagnetic valve, the laser receiver is electrically connected with the valve, and the laser receiver controls opening and closing of the valve according to a received laser wavelength.

[0026] The one or more technical solutions described above in the embodiments of the present application have at least the following technical effects or advantages:

[0027] The industrial sodium chlorate content determination method and device for sodium chlorate in industrial sodium hypochlorite solution provided by the embodiments of the present application effectively eliminate the interference of sodium hypochlorite on the determination of sodium chlorate content by adding hydrogen peroxide to destroy sodium hypochlorite (excess hydrogen peroxide can be removed by heating decomposition), so that the subsequent determination result is more accurate and reliable. Moreover, by titrating excess ferrous ions and calculating the volume and concentration of the consumed potassium dichromate standard solution, the mass concentration of sodium chlorate can be accurately calculated, providing accurate data support for subsequent process adjustment or product application. Finally, the determination method provided by the embodiments of the present application has clear steps and is simple to operate. Through steps such as neutralization, reduction, and titration, the content of sodium chlorate in industrial sodium hypochlorite solution can be systematically determined, and the experimental efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0029] Figure 1 The flowchart of the industrial sodium chlorate content determination method for sodium chlorate in industrial sodium hypochlorite solution provided by the embodiments of the present application is shown in the figure.

[0030] Figure 2 The structural schematic diagram of the industrial sodium chlorate content determination device for sodium chlorate in industrial sodium hypochlorite solution provided by the embodiments of the present application is shown in the figure.

[0031] Figure 3 The structural schematic diagram of the industrial sodium chlorate content determination device for sodium chlorate in industrial sodium hypochlorite solution provided by the embodiments of the present application is shown in the figure.

[0032] Among them, various reference signs are as follows:

[0033] 1, mounting frame; 2, burette; 3, conical flask; 4, oscillation device; 11, connecting part; 21, valve; 41, mounting ring; 42, electromagnet; 51, laser generator; 52, laser receiver; 111, metal ring; 112, flexible pad. DETAILED DESCRIPTION

[0034] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like component have the same or similar designations. The embodiments described below are presented by way of example to explain the present application, and are not intended to limit the present application.

[0035] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0036] In addition, the terms "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified and limited.

[0037] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] Please refer to Figure 1 The embodiment of the present application provides a method for determining the content of sodium chlorate in industrial sodium hypochlorite solution, comprising the following steps:

[0039] a. Eliminate the interference of sodium hypochlorite: add hydrogen peroxide to the industrial sodium hypochlorite solution to be measured, so that it is excessive to destroy sodium hypochlorite;

[0040] b. Neutralize sodium hydroxide: use sulfuric acid solution to neutralize sodium hydroxide in sodium hypochlorite solution;

[0041] c. Reduce sodium chlorate: in an acidic environment, add ferrous sulfate as a reducing agent to the treated solution to reduce sodium chlorate to chloride ion;

[0042] d. Titration of residual ferrous ions: using sodium diphenylamine sulfonate as an indicator, the excess ferrous ions were titrated with 0.1 mol / L potassium dichromate standard titration solution until the solution color changed to purple, reaching the titration end point;

[0043] e. Calculation of sodium chlorate content: according to the volume and concentration of the potassium dichromate standard solution consumed in titration, the mass concentration of sodium chlorate was calculated.

[0044] This example utilizes the different oxidation capacities of sodium hypochlorite and sodium chlorate, digests the influence of sodium hypochlorite with hydrogen peroxide, neutralizes sodium hydroxide in sodium hypochlorite solution with sulfuric acid, uses ferrous sulfate as a reducing agent to reduce sodium chlorate in the sample, and then uses potassium dichromate standard solution to oxidize the excess ferrous sulfate, thereby determining the accurate concentration of sodium chlorate. The method is simple and reliable, with high recovery rate and detection limit (mass concentration) of 0.05 g / l or less.

[0045] Among them, the reaction formula for digesting sodium hypochlorite with hydrogen peroxide is as follows:

[0046]

[0047] The reaction formula for neutralizing sodium hydroxide with sodium hydroxide is as follows:

[0048]

[0049] The reaction formula for reducing sodium chlorate with ferrous sulfate is as follows:

[0050]

[0051] The excess ferrous ions were titrated with 0.1 mol / L potassium dichromate standard titration solution to the end point using sodium diphenylamine sulfonate as an indicator. The reaction formula is as follows:

[0052]

[0053] 1. Specific determination method:

[0054] Accurately pipette 5.00 mL of the sample into a 250 mL conical flask 3 which has been pre-filled with 20 mL of distilled water. Then, add 3% hydrogen peroxide solution into the conical flask 3 to neutralize sodium hypochlorite and ensure 0.5 mL excess. Next, neutralize sodium hydroxide with a half sulfuric acid solution (i.e. (1 / 2) H2SO4) having a concentration of 6 mol / L. After that, add 20 mL of saturated sodium carbonate solution and 20 mL of water, heat the mixture to boiling for 5 minutes, and then cool to room temperature. Then, add 20 mL of sulfuric acid solution having a concentration of 6 mol / L and 25 mL of ferrous sulfate standard solution having a concentration of 0.1 mol / L into the conical flask 3, quickly seal the bottle mouth with a one-way air outlet rubber plug, and heat to boiling again for 10 minutes. Immediately remove and quickly cool after boiling, then add 100 mL of distilled water and 10 mL of (1+1) phosphoric acid solution, and then add 6-8 drops of sodium diphenylamine sulfonate indicator solution. Finally, use the potassium dichromate standard solution having a concentration of 0.1 mol / L to titrate until the solution suddenly turns purple, which is the end point. At the same time, perform a blank test for comparison.

[0055] 2. Result calculation:

[0056] The sodium chlorate content is expressed by the mass concentration X of sodium chlorate, and the value is expressed in g / L, according to formula (1):

[0057] (1)

[0058] In the formula:

[0059] V2 - the value of the volume of the potassium dichromate standard titration solution in the blank test, in milliliters (mL);

[0060] V1 - the value of the volume of the potassium dichromate standard titration solution, in milliliters (mL);

[0061] c - the accurate value of the concentration of the potassium dichromate standard titration solution, in moles per liter (mol / L);

[0062] 0.01775 - the mass of sodium chlorate in grams corresponding to 1.00 mL of potassium dichromate standard solution [c(1 / 6 K2Cr2O7) = 1.000 mol / L].

[0063] Due to the characteristics of sodium hypochlorite solution, it cannot be stored for a long time and is unstable and easily decomposed into sodium chlorate, so it must be measured in time. In order to verify the precision and reliability of the determination method, one sample was taken at the same time and in different places, and the sample was measured at the same time and the precision and recovery rate test was carried out by adding 5 ml of 2 g / L sodium chlorate standard solution. The results are shown in Table 1.

[0064] Table 1 Precision and recovery rate of test method

[0065]

[0066] From Table 1, it can be seen that the method has high precision, the standard deviation of multiple determination results is 0.03%-0.08%, and the recovery rate is 90.0%-104%, which can fully meet the requirements of daily analysis and detection.

[0067] In the elimination of interference, in the sodium hypochlorite solution, the substances that interfere with the determination are mainly Cl - , ClO - , sodium hydroxide, and the ferric ion generated after the reaction of the reducing agent ferrous sulfate; Cl - elimination mainly uses acidity control to exclude its interference; ClO - uses hydrogen peroxide as a reducing agent under alkaline conditions (under which conditions ClO -3 cannot oxidize hydrogen peroxide) to eliminate it, and the excess hydrogen peroxide can be removed by heating, and sodium hydroxide is neutralized with 6 mol / l sulfuric acid; the interference of ferric ion is eliminated by adding phosphoric acid.

[0068] In terms of acidity control: according to the reaction principle, the reaction of ClO -3 and K2Cr2O7 oxidizing Fe 3+ must be carried out under acidic conditions. If the acidity is too weak, the reaction of sodium chlorate and ferrous sulfate will not be complete, and if the acidity is too strong, it will inevitably affect the removal of Cl - By neutralizing the sodium hydroxide in the sodium hypochlorite solution with sulfuric acid, adding 6 mol / L sulfuric acid solution 20 mL and (1+1) phosphoric acid solution 10 mL to the test solution, the acidity control requirements can be met, and satisfactory analysis results can be obtained.

[0069] In terms of the selection of standard solution: choosing potassium dichromate as the standard solution can minimize the interference of Cl- and make the color change at the end point accurate and easy to judge. In the traditional titration method, when potassium permanganate is used as the standard solution, the end point is unstable and is easily oxidized, which affects the accuracy of the determination results.

[0070] In step d, phosphoric acid solution is added to the solution before titration to eliminate the interference of ferric ion, and at the same time, the acidity of the solution is adjusted. Among them, phosphoric acid can combine with the ferric ion (Fe 3+ ) generated in the titration process to form colorless coordination ions (such as Fe(HPO4) 2- ), thereby eliminating the yellow interference of ferric ion. This is crucial for accurate determination of the end point, because the color of ferric ion may mask the color change at the end point of titration, affecting the accuracy of titration.

[0071] And the addition of phosphoric acid can also adjust the degree of acidity of the solution, so that it remains within a suitable range. This is very important for some titration reactions, because different titration reactions have different requirements for the acidity and alkalinity of the solution. A suitable acidic environment helps the smooth progress of the titration reaction, improves the accuracy and reliability of the titration.

[0072] In addition, phosphoric acid also has a certain buffering effect, which can resist the influence of the addition of a small amount of acid and base from the outside on the pH value of the solution. This buffering effect helps to keep the pH value of the solution relatively stable during titration, further improving the accuracy of titration.

[0073] Finally, the addition of phosphoric acid can also reduce the concentration of Fe 3+ , thereby reducing the potential difference of Fe 3+ / Fe 2+ , and lengthening the range of the sudden change of the lower part of the titration curve. This helps to prevent the early arrival of the titration end point, ensuring the accuracy of the titration results.

[0074] In summary, phosphoric acid plays multiple roles in the titration process, such as eliminating interference, adjusting acidity and alkalinity, buffering, and preventing the early arrival of the titration end point. These effects together ensure the smooth progress of the titration process and the accuracy of the titration results.

[0075] When titrating, the tester first reads the liquid level reading of the titration solution in the burette 2, then opens the valve 21 on the burette 2, allowing the titration solution (0.1 mol / L potassium dichromate standard solution) in the burette 2 to slowly drip from the bottom outlet into the conical flask 3 below until the solution in the conical flask 3 changes color. Then the tester needs to quickly close the valve 21 to avoid consuming too much titration solution and affecting the test results. At this time, the liquid level reading of the titration solution in the burette 2 is read again, and the titration step is completed. During the titration process, the tester needs to concentrate on observing whether the solution in the conical flask 3 changes and controlling the valve 21, and also needs to shake and oscillate the conical flask 3 to speed up the reaction speed inside it, in order to improve the accuracy of the titration results. When shaking and oscillating the conical flask 3, it is also necessary to ensure that the titration solution falls directly into the solution in the conical flask 3, rather than falling on the inner wall of the conical flask 3 (dropping on the inner wall of the conical flask 3 will cause part of the titration solution to not react with the solution in the conical flask 3 in time, thereby affecting the titration accuracy). Therefore, the titration process has high technical requirements for the tester.

[0076] In order to reduce the titration difficulty, reduce the technical difficulty of the detection personnel in the titration process. Another purpose of the present application is to provide a device for measuring the content of sodium chlorate in industrial sodium hypochlorite solution, which is used for the method for measuring the content of sodium chlorate in industrial sodium hypochlorite solution in any one of the above embodiments. The device for measuring the content of sodium chlorate in industrial sodium hypochlorite solution comprises a conical flask 3, a burette 2 and a mounting bracket 1. The burette 2 is mounted on the mounting bracket 1, the burette 2 contains titration solution, and the bottom of the burette 2 is provided with a valve 21. The mouth of the conical flask 3 is connected to the mounting bracket 1 through a connecting part 11, the conical flask 3 is located directly below the burette 2, and the conical flask 3 contains the titration solution. The connecting part 11 comprises a metal ring 111 at the outer ring and a flexible pad 112 at the inner ring (which can be made of rubber material), the flexible pad 112 is arranged at the inner ring of the metal ring 111, the mouth of the conical flask 3 is sleeved in the flexible pad 112, and the metal ring 111 is fixed on the mounting bracket 1, so that when the mouth of the conical flask 3 is mounted on the mounting bracket 1, the bottom of the conical flask 3 can be shaken.

[0077] The device for measuring the content of sodium chlorate in industrial sodium hypochlorite solution provided in the present embodiment is installed on the mounting bracket 1 through the connecting part 11, so that when titration is performed, the detection personnel only need to shake the bottom of the conical flask 3, which can make the conical flask 3 shake in the front-back and left-right directions around the connecting part 11 (since the mouth of the conical flask 3 is mounted on the mounting bracket 1 through the connecting part 11, and the flexible pad 112 of the connecting part 11 has a certain elasticity and yieldability, so that the mouth of the conical flask 3 can be fixed while also shaking back and forth in a small range), thereby accelerating the reaction speed of the titration solution and the solution in the conical flask 3. When the detection personnel shakes the bottom of the conical flask 3, the shaking amplitude of the bottom of the conical flask 3 is large, while the shaking amplitude of the mouth of the conical flask 3 is small (limited in the metal ring 111). The solution in the bottom of the conical flask 3 can be fully mixed, and the reaction speed of the titration solution and the solution in the conical flask 3 is ensured. Since the shaking amplitude of the mouth of the conical flask 3 is small, the titration solution dropped from the upper burette 2 can smoothly enter the bottom of the conical flask 3 through the mouth of the conical flask 3 (the conical flask 3 is narrow at the top and wide at the bottom, so even if the shaking amplitude of the bottom of the conical flask 3 is large, the titration solution is not easy to drop on the inner wall of the bottom of the conical flask 3), which is not easy to drop on the inner wall of the conical flask 3, thereby ensuring the accuracy of the titration. Further, the difficulty of the detection personnel in shaking the conical flask 3 is reduced, and the titration difficulty is reduced.

[0078] In addition, due to the slow liquid outlet speed of the burette 2 in the titration process, the consumed time is long. In this process, if the detection personnel need to hold the conical flask 3 and continuously shake the conical flask 3, it is easy to cause the detection personnel to be tired and hand sore. The industrial sodium chlorate content determination device provided in the embodiment installs the conical flask 3 on the mounting rack 1 through the connecting part 11, and then the detection personnel do not need to hold the conical flask 3, only need to move the bottom of the conical flask 3 back and forth to shake the conical flask 3, save the force consumed by holding the conical flask 3 for a long time, so that the detection personnel titration process is more relaxed.

[0079] In one embodiment, the oscillation device 4 is further included, the oscillation device 4 is arranged on the conical flask 3, and the oscillation device 4 includes a mounting ring 41 and an electromagnet 42. The mounting ring 41 is sleeved on the neck of the conical flask 3, the electromagnet 42 is arranged on the mounting ring 41, and the metal ring 111 is made of ferromagnetic metal material.

[0080] When titration is performed, the electromagnet 42 works intermittently, so that the magnetic attraction between the electromagnet 42 and the metal ring 111 is intermittently generated. When the electromagnet 42 is powered on, the magnetic attraction between the electromagnet 42 and the metal ring 111 makes the conical flask 3 swing to the side where the electromagnet 42 is located. When the electromagnet 42 is powered off, the magnetic attraction disappears, and the self-gravity of the conical flask 3 makes the conical flask 3 swing to the other side and reset, thereby realizing automatic oscillation of the conical flask 3.

[0081] By arranging the oscillation device 4, the shaking and oscillation action of the conical flask 3 is automatically performed, without manual operation of the detection personnel, so as to facilitate the detection personnel to concentrate on observing the color change in the conical flask 3 and controlling the valve 21.

[0082] Optionally, a plurality of electromagnets 42 can be uniformly arranged on the mounting ring 41, and each electromagnet 42 is sequentially powered on and powered off, so that the oscillation device 4 can make the conical flask 3 swing in different directions, and the oscillation effect is improved.

[0083] In one embodiment, the control part is further included, and the control part includes a laser receiver 52 and a laser generator 51. The laser generator 51 is arranged at the bottom of the burette 2, and the light emitting direction of the laser generator 51 is vertically downward. The laser receiver 52 is flat and attached to the bottom of the conical flask 3. The laser receiver 52 is electrically connected with the electromagnet 42.

[0084] By setting the laser generator 51, the light beam emitted by the laser generator 51 is used to simulate the titration solution dropped by the burette 2, when the light beam emitted by the laser generator 51 can be received by the laser receiver 52 below, it indicates that the titration solution dropped by the burette 2 can be normally dropped into the solution in the conical flask 3, instead of being dropped on the inner wall of the conical flask 3 or even outside the conical flask 3. Further, by electrically connecting the laser receiver 52 with the electromagnet 42, when the laser receiver 52 fails to receive the light beam emitted by the laser generator 51, it indicates that the oscillation swing amplitude of the conical flask 3 is too large, at this time, the laser receiver 52 will control the electromagnet 42 in the oscillation device 4 to reduce the current size in the electromagnet 42, and then reduce the magnetic attraction between the electromagnet 42 and the metal ring 111, so as to reduce the oscillation swing amplitude of the conical flask 3, and ensure that the titration solution dropped by the burette 2 can be normally dropped into the solution in the conical flask 3.

[0085] Optionally, the receiving surface of the laser receiver 52 can be in the shape of a circular plate, and the center of the receiving surface is coincided with the center of the bottom surface of the conical flask 3. The size of the receiving surface can be the size of the bottom surface of a circular cone with the center of the mouth of the conical flask 3 as the top point and the bottom of the neck of the conical flask 3 as the bottom surface, keeping the same taper and extending downward to the bottom surface of the conical flask 3.

[0086] In an embodiment, the valve 21 is an electromagnetic valve, the laser receiver 52 is electrically connected with the valve 21, and the laser receiver 52 controls the opening and closing of the valve 21 according to the received laser wavelength. The light beam emitted by the laser generator 51 is received by the laser receiver 52 after passing through the solution in the conical flask 3, when the color of the solution in the conical flask 3 changes (such as becoming purple), since the solution absorbs all colors of light except the color of the solution, the color of the light beam entering the laser receiver 52 will change with the change of the color of the solution, and then when the laser receiver 52 receives the end point color of titration (the laser receiver 52 judges the color according to different color wavelengths, when the color changes, the wavelength of the entering light beam changes accordingly), the laser receiver 52 quickly controls the valve 21 to close. Compared with the traditional manual control of the valve 21 by the tester according to the change of the solution in the conical flask 3, the embodiment adopts an automatic control mode, has high sensitivity and fast response speed, can close the valve 21 at the first time when the color of the solution changes, and ensures the accuracy of detection.

[0087] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A device for determining the sodium chlorate content in an industrial sodium hypochlorite solution, used for determining the sodium chlorate content in an industrial sodium hypochlorite solution, characterized in that, The apparatus for determining the sodium chlorate content in the industrial sodium hypochlorite solution includes: Mounting rack; A burette, which is mounted on the mounting bracket, contains a titration solution, and has a valve at its bottom; A conical flask, the mouth of which is connected to the mounting bracket via a connecting part, the conical flask being located directly below the burette, and the conical flask containing the solution to be titrated; The connecting part includes an outer metal ring and an inner flexible pad. The flexible pad is disposed in the inner ring of the metal ring. The mouth of the conical bottle is fitted inside the flexible pad. The metal ring is fixed to the mounting bracket so that when the mouth of the conical bottle is installed on the mounting bracket, the bottom of the conical bottle can swing. It also includes a shaking device, which is disposed on the conical flask, and the shaking device includes: Mounting ring, which is fitted onto the neck of the conical flask; An electromagnet, wherein the electromagnet is disposed on the mounting ring; The metal ring is made of a ferromagnetic metal material; It also includes a control unit, which includes: A laser generator is disposed at the bottom of the burette, and the laser emission direction of the laser generator is vertically downward; A laser receiver, which is planar and attached to the bottom of the conical flask; the laser receiver is electrically connected to the electromagnet. The determination of sodium chlorate content in the industrial sodium hypochlorite solution includes the following steps: a. Eliminate interference from sodium hypochlorite: Add hydrogen peroxide to the industrial sodium hypochlorite solution to be tested, making it excessive, so as to destroy the sodium hypochlorite; b. Neutralize sodium hydroxide: Neutralize the sodium hydroxide in the sodium hypochlorite solution with sulfuric acid solution; c. Reduction of sodium chlorate: In an acidic environment, ferrous sulfate is added to the treated solution as a reducing agent to reduce sodium chlorate to chloride ions; d. Titration of excess ferrous ions: Using sodium diphenylamine sulfonate as an indicator, titrate the excess ferrous ions with 0.1 mol / L potassium dichromate standard titration solution until the solution color changes abruptly to purple, reaching the titration endpoint; e. Calculate the sodium chlorate content: Calculate the mass concentration of sodium chlorate based on the volume and concentration of the potassium dichromate standard solution consumed in the titration.

2. The apparatus for determining the sodium chlorate content in an industrial sodium hypochlorite solution according to claim 1, characterized in that: In step a, the amount of hydrogen peroxide added is such that the sodium hypochlorite is completely destroyed and there is an excess of 0.5 mL.

3. The apparatus for determining the sodium chlorate content in an industrial sodium hypochlorite solution according to claim 1, characterized in that: In step c, the concentration of the ferrous sulfate standard solution is 0.1 mol / L, and the reduction reaction is carried out under heating and boiling conditions.

4. The apparatus for determining the sodium chlorate content in an industrial sodium hypochlorite solution according to claim 1, characterized in that: Step d also includes adding phosphoric acid solution to the solution before titration to eliminate interference from ferric ions and adjust the acidity of the solution.

5. The apparatus for determining the sodium chlorate content in an industrial sodium hypochlorite solution according to claim 1, characterized in that: The valve is an electromagnetic gate, and the laser receiver is electrically connected to the valve. The laser receiver controls the opening and closing of the valve according to the received laser wavelength.

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