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

Abstract

The invention provides a method and device for determining the content of sodium chlorate in an industrial sodium hypochlorite solution, and the method comprises the following steps: a, eliminating the interference of sodium hypochlorite: adding hydrogen peroxide into a to-be-detected industrial sodium hypochlorite solution to enable the hydrogen peroxide to be excessive so as to destroy sodium hypochlorite; b, neutralizing sodium hydroxide: neutralizing the sodium hydroxide by using a sulfuric acid solution; c, reducing sodium chlorate: adding ferrous sulfate as a reducing agent into the treated solution in an acidic environment, and reducing sodium chlorate into chloride ions; d, titrating residual ferrous ions: taking sodium diphenylaminesulfonate as an indicator, titrating the excessive ferrous ions by using 0.1 mol / L of potassium dichromate standard titration solution until the color of the solution is suddenly changed to purple, and reaching a titration end point; and e, calculating the content of sodium chlorate: calculating the mass concentration of sodium chlorate according to the volume and concentration of the potassium dichromate standard solution consumed by titration. The method and the device for determining the content of sodium chlorate in the industrial sodium hypochlorite solution have the advantage that the determination result is more accurate and reliable.

Description

Technical Field

[0001] The invention relates to the technical field of ADC foaming agent production, in particular to a method and a device for determining the sodium chlorate content in an industrial sodium hypochlorite solution. Background Art

[0002] The current domestic production process of ADC foaming agent is mainly urea oxidation method, with urea, chlorine and caustic soda as starting materials, first prepare hydrazine hydrate, use the prepared hydrazine hydrate and urea to generate biurea under the action of sulfuric acid, then use chlorine to oxidize to obtain ADC foaming agent, and obtain the finished product after washing, centrifugation and drying. When preparing hydrazine hydrate, it is necessary to first use chlorine and liquid alkali to react to obtain sodium hypochlorite solution, and the reaction of chlorine and liquid alkali will produce a side reaction to generate sodium chlorate. At the same time, the nature of sodium hypochlorite is also unstable and will decompose to generate sodium chlorate. When sodium chlorate is in the process of chlorine oxidation of biurea, it has a certain influence on the yield of biurea converted into ADC foaming agent, so it is necessary to monitor the sodium chlorate content in industrial sodium hypochlorite. Although there are reports on the research on chlorate determination method at home and abroad, there are few reports on the detection of sodium chlorate in sodium hypochlorite solution. Summary of the invention

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

[0004] To achieve the above object, the technical solution adopted by the present invention is: to provide a method for determining the content of sodium chlorate in an industrial sodium hypochlorite solution, comprising the following steps: a. Eliminate the interference of sodium hypochlorite: add hydrogen peroxide to the industrial sodium hypochlorite solution to be tested to make it excessive to destroy the sodium hypochlorite; b. Neutralize sodium hydroxide: Use sulfuric acid solution to neutralize the sodium hydroxide in the sodium hypochlorite solution; c. Reducing 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. Titrate the remaining ferrous ions: Using sodium diphenylamine sulfonate as an indicator, use 0.1 mol / L potassium dichromate standard titration solution to titrate the excess ferrous ions until the color of the solution suddenly changes 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.

[0005] In one embodiment, the amount of hydrogen peroxide added in step a is 0.5 mL in excess to completely destroy the sodium hypochlorite.

[0006] 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 heating and boiling conditions.

[0007] In one embodiment, step d also includes adding phosphoric acid solution to the solution before titration to eliminate the interference of trivalent iron ions and adjust the acidity of the solution.

[0008] Another object of the present invention is to provide a device for determining the content of sodium chlorate in an industrial sodium hypochlorite solution, which is used to perform the method for determining the content of sodium chlorate in an industrial sodium hypochlorite solution described in any one of the above embodiments, and the device for determining the content of sodium chlorate in an industrial sodium hypochlorite solution comprises: Mounting frame; A burette, the burette is mounted on the mounting frame, the burette is filled with a titration solution, and a valve is provided at the bottom of the burette; A conical flask, the mouth of which is connected to the mounting frame via a connecting portion, the conical flask is located directly below the burette, and the conical flask contains a titrated solution; The connecting part includes an outer metal ring and an inner flexible pad, the flexible pad is arranged on the inner ring of the metal ring, the mouth of the conical flask is sleeved in the flexible pad, and the metal ring is fixed on the mounting frame so that when the mouth of the conical flask is mounted on the mounting frame, the bottom of the conical flask can shake.

[0009] In one embodiment, an oscillating device is further included, and the oscillating device is disposed on the conical flask, and the oscillating device includes: A mounting ring, the mounting ring being sleeved on the bottleneck of the conical flask; an electromagnet, wherein the electromagnet is disposed on the mounting ring; The metal ring is made of ferromagnetic metal material.

[0010] In one embodiment, a control unit is further included, wherein the control unit includes: A laser generator, which is disposed at the bottom of the burette and whose light emission direction is vertically downward; A laser receiver is planar and attached to the bottom of the conical flask; the laser receiver is electrically connected to the electromagnet.

[0011] In one embodiment, the valve is an electromagnetic valve, the laser receiver is electrically connected to the valve, and the laser receiver controls the opening and closing of the valve according to the wavelength of the received laser.

[0012] One or more of the above technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: The method and device for determining the content of sodium chlorate in the industrial sodium hypochlorite solution provided by the embodiment of the present invention, by adding hydrogen peroxide to destroy sodium hypochlorite (excess hydrogen peroxide can be removed by heating and decomposition), effectively eliminates the interference of sodium hypochlorite on the determination of the content of sodium chlorate, so that the subsequent determination results are more accurate and reliable. In addition, by titrating the 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 adjustments or product applications. Finally, the determination method provided by the embodiment of the present application has clear steps and is easy to operate. Through the steps of neutralization, reduction, titration, etc., the sodium chlorate content in the industrial sodium hypochlorite solution can be systematically determined, and the experimental efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 A flow chart of a method for determining the content of sodium chlorate in an industrial sodium hypochlorite solution provided by an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a device for measuring the sodium chlorate content in an industrial sodium hypochlorite solution provided by an embodiment of the present invention; Figure 3 A schematic structural diagram of another perspective of a device for measuring sodium chlorate content in an industrial sodium hypochlorite solution provided in an embodiment of the present invention.

[0015] The respective reference numerals are as follows: 1. Mounting frame; 2. Burette; 3. Conical flask; 4. Oscillating 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

[0016] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0017] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0018] In addition, 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. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0019] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] See also Figure 1 The present application embodiment provides a method for determining the content of sodium chlorate in an industrial sodium hypochlorite solution, comprising the following steps: a. Eliminate the interference of sodium hypochlorite: add hydrogen peroxide to the industrial sodium hypochlorite solution to be tested to make it excessive to destroy the sodium hypochlorite; b. Neutralize sodium hydroxide: Use sulfuric acid solution to neutralize the sodium hydroxide in the sodium hypochlorite solution; c. Reducing 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. Titrate the remaining ferrous ions: Using sodium diphenylamine sulfonate as an indicator, use 0.1 mol / L potassium dichromate standard titration solution to titrate the excess ferrous ions until the color of the solution suddenly changes 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.

[0021] This embodiment utilizes the different oxidizing abilities of sodium hypochlorite and sodium chlorate, uses hydrogen peroxide to eliminate the influence of sodium hypochlorite, uses sulfuric acid to neutralize the sodium hydroxide in the sodium hypochlorite solution, uses ferrous sulfate as a reducing agent, reduces the 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, the measured recovery rate is high, and the detection limit (mass concentration) can reach below 0.05g / l.

[0022] Among them, the reaction formula for digesting sodium hypochlorite with hydrogen peroxide is as follows:

[0023] The reaction formula of using sodium hydroxide to neutralize sodium hydroxide is as follows:

[0024] The reaction formula for reducing sodium chlorate using ferrous sulfate is as follows:

[0025] Excess ferrous ions are titrated to the endpoint using 0.1 mol / L potassium dichromate standard titration solution with sodium diphenylamine sulfonate as an indicator. The reaction formula is as follows:

[0026] 1. Specific determination method: Use a pipette to accurately measure 5.00 mL of the sample and add it to a 250 mL conical flask 3 that has been pre-filled with 20 mL of distilled water. Then, add a 3% hydrogen peroxide solution to the conical flask 3 to neutralize the sodium hypochlorite and ensure that it is 0.5 mL in excess. Then, use 6 mol / L hemisulphuric acid (i.e. (1 / 2) H 2 SO 4 ) solution to neutralize the sodium hydroxide. After that, add 20mL of saturated sodium carbonate solution and 20mL of water, heat and boil the mixture for 5 minutes, and then cool it to room temperature. Subsequently, add 20mL of 6mol / L sulfuric acid solution and 25mL of 0.1mol / L ferrous sulfate standard solution to conical flask 3, quickly plug the bottle mouth with a one-way air outlet rubber stopper, and heat and boil again for 10 minutes. After boiling, remove it immediately and cool it quickly, then add 100mL of distilled water and 10mL of (1+1) phosphoric acid solution, and then add 6 to 8 drops of sodium diphenylamine sulfonate indicator solution. Finally, use a 0.1mol / L potassium dichromate standard solution for titration until the solution suddenly turns purple, which is the end point. At the same time, a blank test is performed for control.

[0027] 2. Calculation of results: The sodium chlorate content is measured by the mass concentration X of sodium chlorate, and the value is expressed in g / L, which is expressed by formula (1): (1) Where: V2 - the volume of potassium dichromate standard titration solution during blank test, in milliliters (mL); V1 - the volume of potassium dichromate standard titration solution, in milliliters (mL); c-the exact value of the concentration of potassium dichromate standard titration solution, in moles per liter (mol / L); 0.01775 - The mass of sodium chlorate expressed in grams equivalent to 1.00 mL of potassium dichromate standard solution [c(1 / 6K2Cr2O7) = 1.000 mol / L].

[0028] 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 this determination method, this test adopts a sample taken at the same time and different locations, and the sample is measured and 5ml2g / l sodium chlorate standard solution is added to perform precision and recovery tests. The results are shown in Table 1.

[0029] Table 1 Precision and recovery of the test method

[0030] As can be seen from Table 1, this method has high precision, the standard deviation of multiple measurement results is between 0.03% and 0.08%, and the recovery rate is between 90.0% and 104%, which can fully meet the requirements of daily analysis and testing.

[0031] In this application, the elimination of interferences is as follows: In the sodium hypochlorite solution, the substances that interfere with this determination are mainly Cl - , ClO - , sodium hydroxide and the trivalent iron ion generated by the reaction of adding the reducing agent ferrous sulfate; Cl - Elimination is mainly achieved by controlling acidity to eliminate its interference; ClO - Using alkaline conditions (ClO -3 Hydrogen peroxide cannot be oxidized) Hydrogen peroxide is added as a reducing agent to eliminate it. Excess hydrogen peroxide can be removed by heating. Sodium hydroxide is neutralized with 6 mol / l sulfuric acid; the interference of trivalent iron ions is eliminated by adding phosphoric acid.

[0032] In terms of acidity control: According to the reaction principle, ClO -3 and K 2 Cr 2 O 7 Oxidation of Fe 3+The reaction must be carried out under acidic conditions. If the acid is too weak, the reaction between sodium chlorate and ferrous sulfate will not be complete. If the acid is too strong, it will inevitably affect the Cl - By first neutralizing the sodium hydroxide in the sodium hypochlorite solution with sulfuric acid, and then adding 20 mL of 6 mol / L sulfuric acid solution and 10 mL of (1+1) phosphoric acid solution to the test solution, the acidity control requirement can be met and satisfactory analysis results can be obtained.

[0033] In terms of the selection of standard solution for determination: choosing potassium dichromate as the standard solution for determination can not only minimize the interference of Cl-, but also make the color change and interpretation of the end point accurate. When potassium permanganate is used as the standard solution in the traditional titration method, the end point is unstable and is easily oxidized, thus affecting the accuracy of the determination result.

[0034] In step d, phosphoric acid solution is added to the solution before titration to eliminate the interference of trivalent iron ions and adjust the acidity of the solution. Phosphoric acid can react with trivalent iron ions (Fe 3+ ) to form colorless coordination ions (such as Fe(HPO 4 ) 2- ), thereby eliminating the yellow interference of ferric ions. This is crucial for the accurate judgment of the titration endpoint, because the color of ferric ions may mask the color change of the titration endpoint and affect the accuracy of the titration.

[0035] The addition of phosphoric acid can also adjust the acidity of the solution to keep it within an appropriate 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 titration reaction proceed smoothly and improves the accuracy and reliability of the titration.

[0036] In addition, phosphoric acid also has a certain buffering effect, which can resist the influence of small amounts of acid and alkali added from the outside on the pH value of the solution. This buffering effect helps to maintain the relative stability of the pH value of the solution during the titration process, further improving the accuracy of the titration.

[0037] Finally, the addition of phosphoric acid can also reduce Fe 3+ concentration, thereby reducing Fe 3+ / Fe 2+ The potential difference is increased, and the jump range of the lower part of the titration curve is extended. This helps to prevent the titration endpoint from being reached prematurely and ensure the accuracy of the titration result.

[0038] In summary, phosphoric acid plays multiple roles in the titration process, including eliminating interference, adjusting acidity and alkalinity, buffering, and preventing the titration endpoint from reaching prematurely. These roles jointly ensure the smooth progress of the titration process and the accuracy of the titration results.

[0039] When performing titration, the tester first reads the liquid level reading of the titration solution in the burette 2, and then opens the valve 21 on the burette 2, so that the titration solution (0.1 mol / L potassium dichromate standard solution) in the burette 2 slowly drips 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, read the liquid level reading of the titration solution in the burette 2 again to complete the titration step. During the titration process, the tester needs to concentrate on observing whether the solution in the conical flask 3 changes and control the valve 21, and also needs to shake and vibrate the conical flask 3 to accelerate the reaction speed inside it to improve the accuracy of the titration result. And when shaking and oscillating the conical flask 3, it is also necessary to ensure that the titration solution can directly fall into the solution in the conical flask 3, rather than dripping on the inner wall of the conical flask 3 (dripping on the inner wall of the conical flask 3 will cause part of the titration solution to fail to 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 testing personnel.

[0040] In order to reduce the difficulty of titration, reduce the technical difficulty of the titration process for the testers. Another object of the present invention is to provide a device for determining the content of sodium chlorate in an industrial sodium hypochlorite solution, which is used to perform the method for determining the content of sodium chlorate in an industrial sodium hypochlorite solution in any of the above embodiments. The device for determining the content of sodium chlorate in an industrial sodium hypochlorite solution comprises a conical flask 3, a burette 2, and a mounting frame 1. Among them, the burette 2 is mounted on the mounting frame 1, the burette 2 is filled with a titration solution, and a valve 21 is provided at the bottom of the burette 2; the mouth of the conical flask 3 is connected to the mounting frame 1 through a connecting portion 11, the conical flask 3 is located directly below the burette 2, and the conical flask 3 is filled with a titrated solution. The connecting portion 11 includes an outer metal ring 111 and an inner flexible pad 112 (specifically, it can be made of rubber material). The flexible pad 112 is arranged on the inner ring of the metal ring 111. The mouth of the conical flask 3 is sleeved in the flexible pad 112. The metal ring 111 is fixed on the mounting frame 1 so that when the mouth of the conical flask 3 is mounted on the mounting frame 1, the bottom of the conical flask 3 can shake.

[0041] The device for determining the sodium chlorate content in the industrial sodium hypochlorite solution provided in this embodiment uses the connecting portion 11 to mount the conical flask 3 on the mounting frame 1, so that when titrating, the inspector only needs to shake the bottom of the conical flask 3 to make the conical flask 3 shake in the front, back, left, and right directions around the connecting portion 11 (because the mouth of the conical flask 3 is mounted on the mounting frame 1 through the connecting portion 11, and the flexible pad 112 of the connecting portion 11 has a certain elasticity and yieldability, so that the mouth of the conical flask 3 can shake back and forth within a small range while being fixed), thereby accelerating the reaction speed of the titration solution and the solution in the conical flask 3. When the inspector 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 within the metal ring 111). The solution at the bottom of the conical flask 3 can be fully mixed, ensuring the reaction speed of the titration solution and the solution in the conical flask 3. Since the shaking amplitude of the conical flask 3 is small, the titration solution dripped from the upper burette 2 can smoothly pass through the conical flask 3 mouth and enter the bottom 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 drip onto the inner wall of the bottom of the conical flask 3), and it is not easy to drip onto the inner wall of the conical flask 3, ensuring the accuracy of the titration. In addition, it is reduced the difficulty of the tester shaking the conical flask 3 and the difficulty of titration.

[0042] In addition, since the liquid discharge speed of the burette 2 is slow during the titration process, a long time is consumed. During this process, if the inspector needs to hold the conical flask 3 and continuously oscillate the conical flask 3, it is easy to cause the inspector's hands to become sore and tired. The sodium chlorate content determination device in the industrial sodium hypochlorite solution provided in this embodiment mounts the conical flask 3 to the mounting frame 1 through the connecting portion 11, so that the inspector does not need to hold the conical flask 3, but only needs to move the bottom of the conical flask 3 back and forth to oscillate the conical flask 3, eliminating the force consumed by holding the conical flask 3 for a long time, making the titration process easier for the inspector.

[0043] In one embodiment, an oscillating device 4 is further included, and the oscillating device 4 is arranged on the conical flask 3, and the oscillating device 4 includes a mounting ring 41 and an electromagnet 42. The mounting ring 41 is sleeved on the bottleneck 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.

[0044] 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 causes the conical flask 3 to swing toward the side where the electromagnet 42 is located. When the electromagnet 42 is powered off, the magnetic attraction disappears, and the conical flask 3 itself The gravity causes the conical flask 3 to swing to the other side and reset, thereby realizing automatic oscillation of the conical flask 3.

[0045] By providing the oscillating device 4 , the shaking and oscillating action of the conical flask 3 is automatically performed without manual operation by the inspector, so that the inspector can concentrate on observing the color change in the conical flask 3 and controlling the valve 21 .

[0046] Optionally, a plurality of electromagnets 42 may be evenly arranged on the mounting ring 41, and each electromagnet 42 is switched on and off in sequence, so that the oscillating device 4 can make the conical flask 3 swing in different directions, thereby improving the oscillation effect.

[0047] In one embodiment, a control unit is further included, and the control unit includes a laser receiver 52 and a laser generator 51. The laser generator 51 is disposed at the bottom of the burette 2, and the light emission direction of the laser generator 51 is vertically downward; the laser receiver 52 is planar and attached to the bottom of the conical flask 3; and the laser receiver 52 is electrically connected to the electromagnet 42.

[0048] By setting up the laser generator 51, the light beam emitted by the laser generator 51 is used to simulate the titration solution dripping from the burette 2. When the light beam emitted by the laser generator 51 can be received by the laser receiver 52 below, it means that the titration solution dripping from the burette 2 can normally drip into the solution of the conical flask 3, rather than dripping onto the inner wall of the conical flask 3 or even outside the conical flask 3. Furthermore, 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 means that the oscillation 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 magnitude of the current in the electromagnet 42, thereby reducing the magnetic attraction between the electromagnet 42 and the metal ring 111, so as to reduce the oscillation amplitude of the conical flask 3 and ensure that the titration solution dripping from the burette 2 can normally drip into the solution of the conical flask 3.

[0049] Optionally, the receiving surface of the laser receiver 52 may be in the shape of a disc, and the center of the receiving surface coincides with the center of the bottom surface of the conical flask 3. The size of the receiving surface may be the size of the bottom surface of a cone with the center of the mouth of the conical flask 3 as the vertex and the bottom of the bottleneck of the conical flask 3 as the bottom surface, with the taper unchanged and extending downward to the bottom of the conical flask 3.

[0050] In one embodiment, the valve 21 is an electromagnetic valve, and the laser receiver 52 is electrically connected to the valve 21. The laser receiver 52 controls the opening and closing of the valve 21 according to the wavelength of the received laser. 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 turning purple), since the solution absorbs all colors of light except the color of the solution, the color of the light beam incident on the laser receiver 52 will change with the color of the solution. Then, when the laser receiver 52 receives the color of the titration endpoint (the laser receiver 52 judges the color according to different color wavelengths, and when the color changes, the wavelength of the incident light beam changes accordingly), the laser receiver 52 quickly controls the valve 21 to close. Compared with the traditional method of manually controlling the opening and closing of the valve 21 according to the change of the solution in the conical flask 3 by the tester, this embodiment adopts an automatic control method with high sensitivity and fast response speed. The valve 21 can be closed at the first time when the color of the solution changes, thereby ensuring the accuracy of the detection.

[0051] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the content of sodium chlorate in an industrial sodium hypochlorite solution, characterized in that: The following steps are involved: a. Eliminate the interference of sodium hypochlorite: add hydrogen peroxide to the industrial sodium hypochlorite solution to be tested to make it excessive to destroy the sodium hypochlorite; b. Neutralize sodium hydroxide: Use sulfuric acid solution to neutralize the sodium hydroxide in the sodium hypochlorite solution; c. Reducing 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. Titrate the remaining ferrous ions: Using sodium diphenylamine sulfonate as an indicator, use 0.1 mol / L potassium dichromate standard titration solution to titrate the excess ferrous ions until the color of the solution suddenly changes 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 method for measuring sodium chlorate content in industrial sodium hypochlorite solution according to claim 1, wherein: In step a, the amount of hydrogen peroxide added is 0.5 mL in excess to completely destroy the sodium hypochlorite.

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

4. The method for measuring sodium chlorate content in industrial sodium hypochlorite solution according to claim 1, wherein: Step d also includes adding a phosphoric acid solution to the solution before titration to eliminate the interference of trivalent iron ions and adjust the acidity of the solution.

5. A device for determining the content of sodium chlorate in an industrial sodium hypochlorite solution, used for carrying out the method for determining the content of sodium chlorate in an industrial sodium hypochlorite solution according to any one of claims 1 to 4, characterized in that: The measuring device of sodium chlorate content in the industrial sodium hypochlorite solution comprises: Mounting frame; A burette, the burette is mounted on the mounting frame, the burette is filled with a titration solution, and a valve is provided at the bottom of the burette; A conical flask, the mouth of which is connected to the mounting frame via a connecting portion, the conical flask is located directly below the burette, and the conical flask contains a titrated solution; The connecting part includes an outer metal ring and an inner flexible pad, the flexible pad is arranged on the inner ring of the metal ring, the mouth of the conical flask is sleeved in the flexible pad, and the metal ring is fixed on the mounting frame so that when the mouth of the conical flask is mounted on the mounting frame, the bottom of the conical flask can shake.

6. The device for measuring sodium chlorate content in industrial sodium hypochlorite solution according to claim 5, characterized in that: It also includes an oscillating device, which is arranged on the conical flask and includes: A mounting ring, the mounting ring being sleeved on the bottleneck of the conical flask; an electromagnet, wherein the electromagnet is disposed on the mounting ring; The metal ring is made of ferromagnetic metal material.

7. The device for measuring sodium chlorate content in industrial sodium hypochlorite solution according to claim 6, characterized in that: Also includes a control unit, the control unit includes: A laser generator, which is disposed at the bottom of the burette and whose light emission direction is vertically downward; A laser receiver is planar and attached to the bottom of the conical flask; the laser receiver is electrically connected to the electromagnet.

8. The device for measuring sodium chlorate content in industrial sodium hypochlorite solution according to claim 7, characterized in that: The valve is an electromagnetic valve, the laser receiver is electrically connected to the valve, and the laser receiver controls the opening and closing of the valve according to the wavelength of the received laser.

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