CN111638211A - Method for detecting chlorate in brine of electrolytic cell - Google Patents
Method for detecting chlorate in brine of electrolytic cell Download PDFInfo
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- CN111638211A CN111638211A CN202010530941.1A CN202010530941A CN111638211A CN 111638211 A CN111638211 A CN 111638211A CN 202010530941 A CN202010530941 A CN 202010530941A CN 111638211 A CN111638211 A CN 111638211A
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- G—PHYSICS
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- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
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- G—PHYSICS
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- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
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Abstract
The invention relates to a method for detecting chlorate in brine of an electrolytic cell, belonging to the technical field of inorganic salt detection. The method comprises the steps of adding 3% of hydrogen peroxide into the brine of the electrolytic cell, removing free chlorine (chlorine and hypochlorite), neutralizing excessive hydrogen peroxide, and finally titrating chlorate. The invention can effectively eliminate the interference of free chlorine on the detection, and the accuracy of the detection result is high.
Description
Technical Field
The invention belongs to the technical field of inorganic salt detection, and particularly relates to a method for detecting chlorate in brine of an electrolytic cell.
Background
The chlor-alkali industry, which is one of the most basic chemical industries, uses the process of electrolyzing saturated brine to prepare sodium hydroxide, hydrogen and chlorine, and the existing production technology is mainly based on an ion exchange membrane process, wherein an anode chamber and a cathode chamber of an electrolytic cell are separated by a cation exchange membrane. Small amounts of chlorate are inevitably formed in the anode compartment during electrolysis. This is because the chlorine gas generated at the anode reacts with water during electrolysis to generate hypochlorous acid, which reacts with a small amount of sodium hydroxide diffused into the anode chamber to generate sodium hypochlorite, and the chlorine gas itself undergoes disproportionation reaction to generate sodium hypochlorite as the sodium hypochlorite accumulates in the anode chamber. Chlorate has strong oxidizing property and is corrosive to the electrolytic cell and equipment in the caustic soda evaporation process, so that the service cycle of the equipment is shortened, and the maintenance cost is increased. Therefore, the chlorate content of the brine of the electrolytic cell needs to be monitored periodically.
According to the oxidizability of chlorate per se, the detection method adopted by chlorate is a titration method, excessive ferrous sulfate is firstly used for reacting with chlorate, then potassium dichromate is used for carrying out back dripping, and the difference value of the two is used for calculating the content of chlorate. However, since a small amount of free chlorine (chlorine and hypochlorite) remains in the brine of the electrolytic cell, the free chlorine and the ferrous sulfate undergo redox reaction, which consumes the ferrous sulfate solution too much, directly resulting in that the detection result does not truly reflect the chlorate content in the brine of the electrolytic cell.
Disclosure of Invention
Aiming at the problem that the content of chlorate in brine of an electrolytic cell cannot be truly detected in the prior art, the invention provides a method for detecting chlorate in brine of an electrolytic cell, which aims to solve the problem. The method comprises the steps of adding 3% of hydrogen peroxide into the brine of the electrolytic cell, removing free chlorine (chlorine and hypochlorite), neutralizing excessive hydrogen peroxide, and finally titrating chlorate. The invention can effectively eliminate the interference of free chlorine on detection.
A detection method of chlorate in brine of an electrolytic cell comprises the following detection principles:
A.H2O2+Cl2＝2H++2Cl-+O2；
H2O2+ClO-＝H2O+Cl-+O2；
B.NaClO3+6FeSO4+3H2SO4＝3Fe2(SO4)3+NaCl+3H2O；
C.6FeSO4+K2Cr2O7+7H2SO4＝3Fe2(SO4)3+Cr2(SO4)3+7H2O+K2SO4。
the specific detection steps are as follows:
(1) sucking a sample from saline water of an electrolytic cell by a pipette, transferring the sample into a volumetric flask containing 100mL of distilled water, diluting the sample to a scale by the distilled water, and fully shaking up;
(2) sucking 25mL of the liquid obtained in the step (1) from a measuring bottle by using a pipette, transferring the liquid into a 300mL triangular flask, dropwise adding 3% hydrogen peroxide, and continuously detecting by using starch-potassium iodide test paper until the test paper does not change color;
(3) to the solution of step (2) were added 60mL of distilled water and 15mL of H2SO4Adding 25mL0.05mol/L FeSO into the solution by using a burette4Adding 2-5 glass balls into the triangular flask, heating the reaction solution to boiling, and cooling to room temperature;
(4) 10mL of H was added to the reaction solution of step (3)3PO4The solution was then added with 6 drops of 3g/L sodium diphenylamine sulfonate indicator and the solution was titrated with a potassium dichromate standard: c (1/6K)2Cr2O7) Titrating the solution to be slightly purple at the rate of 0.1mol/L, and repeating the titrating for 6 times; and simultaneously performing blank test.
(5) Substituting each titration parameter into a calculation formula
Calculating the concentration of chlorate in the brine of the electrolytic cell; the reported values were the average of the results of 6 titration calculations. In the calculation formula:
c0 is the concentration of potassium dichromate standard titration solution, mol/L;
v0 is the volume of the blank potassium dichromate standard titration solution, mL;
v1 is the volume, mL, of the standard titration solution of potassium dichromate consumed by the sample;
v2 is the volume of the sample in step (1), mL;
v3 is the volume of the volumetric flask in the step (1), mL;
106.44 is NaClO3Molar mass of (a), g/mol.
Preferably, the volume of the sample in the step (1) is 10-25 mL.
Preferably, the volume of the volumetric flask in the step (1) is 500 mL.
Preferably, said H2SO4The solution was a mixed solution of 1 volume of 98% concentrated sulfuric acid and 1 volume of distilled water.
Preferably, said H3PO4The solution was a mixed solution of 1 volume of 85% phosphoric acid and 1 volume of distilled water.
Preferably, the blank test is: accurately measuring 25mL of distilled water by using a pipette, placing the distilled water into a 300mL triangular flask, and accurately measuring 25mL of 0.05mol/L FeSO by using the pipette4Adding the standard solution into a triangular flask, and finally adding 15mL of H2SO4Heating the solution to boiling, cooling to room temperature, and adding 10mL of H3PO4Solution and 6 drops of 3g/L sodium diphenylamine sulfonate indicator, standard titration solution with potassium dichromate: c (1/6K)2Cr2O7) Titration was carried out at 0.1mol/L until the reaction mixture became slightly purple. The volume of solution using a standard titration of potassium dichromate is recorded.
The invention has the beneficial effects that:
the method comprises the steps of adding 3% of hydrogen peroxide into the brine of the electrolytic cell, removing free chlorine (chlorine and hypochlorite), neutralizing excessive hydrogen peroxide, and finally titrating chlorate. The invention can effectively eliminate the interference of free chlorine on the detection, and the accuracy of the detection result is high.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A method for detecting chlorate in brine of an electrolytic cell comprises the following specific detection steps:
(1) sucking 25mL of a sample from saline water of an electrolytic tank by a pipette, transferring the sample into a 500mL volumetric flask containing 100mL of distilled water, diluting the sample to a scale by the distilled water, and fully shaking up;
(2) sucking 25mL of the liquid obtained in the step (1) from a measuring bottle by using a pipette, transferring the liquid into a 300mL triangular flask, dropwise adding 3% hydrogen peroxide, and continuously detecting by using starch-potassium iodide test paper until the test paper does not change color;
(3) to the solution of step (2) were added 60mL of distilled water and 15mL of (1+1) H2SO4Adding 25mL0.05mol/L of FeSO by using a burette4Adding a glass ball into the triangular flask, heating the reaction solution to boil, and cooling to room temperature;
(4) 10mL (1+1) of H was added to the reaction solution of step (3)3PO4The solution was then added with 6 drops of 3g/L sodium diphenylamine sulfonate indicator and the solution was titrated with a potassium dichromate standard: c (1/6K)2Cr2O7) Titrating the solution to be slightly purple at the rate of 0.1mol/L, and repeating the titrating for 6 times; and simultaneously performing blank test.
(5) Substituting each titration parameter into a calculation formula
The chlorate concentration in the brine of the electrolytic cell was calculated and the average of the results of 6 titrations was used as the reported value.
The test results for example 1 are given in table 1 below:
TABLE 1 titration test results
| Serial number | V0(mL) | V1(mL) | V2(mL) | V3(mL) | Calculation results (g/L) |
| 1 st time | 11.45 | 7.45 | 25.00 | 500 | 5.68 |
| 2 nd time | 11.50 | 7.50 | 25.00 | 500 | 5.68 |
| 3 rd time | 11.45 | 7.45 | 25.00 | 500 | 5.68 |
| 4 th time | 11.45 | 7.40 | 25.00 | 500 | 5.75 |
| 5 th time | 11.50 | 7.50 | 25.00 | 500 | 5.68 |
| 6 th time | 11.50 | 7.50 | 25.00 | 500 | 5.68 |
| Reporting the value | / | / | / | / | 5.69 |
Example 2
And (3) performing precision test, which comprises the following specific steps:
(1) placing 50mL of 0.5% sodium chlorate standard solution into a triangular flask, adding 0.5mL of fresh chlorine water, uniformly mixing, sucking 25mL of sample by using a pipette, transferring the sample into a 500mL volumetric flask containing 100mL of distilled water, diluting the sample to a scale by using the distilled water, and fully shaking up;
(2) sucking 25mL of the liquid obtained in the step (1) from a measuring bottle by using a pipette, transferring the liquid into a 300mL triangular flask, dropwise adding 3% hydrogen peroxide, and continuously detecting by using starch-potassium iodide test paper until the test paper does not change color;
(3) to the solution of step (2) were added 60mL of distilled water and 15mL of (1+1) H2SO4Adding 25mL0.05mol/L of FeSO by using a burette4Adding glass ball into the triangular flask, and heating the reaction solution to boilCooling to room temperature after boiling;
(4) 10mL (1+1) of H was added to the reaction solution of step (3)3PO4The solution was then added with 6 drops of 3g/L sodium diphenylamine sulfonate indicator and the solution was titrated with a potassium dichromate standard: c (1/6K)2Cr2O7) Titrating the solution to be slightly purple at the rate of 0.1mol/L, and repeating the titrating for 6 times; and simultaneously performing blank test.
(5) Substituting each titration parameter into a calculation formula
Calculating the concentration of chlorate in the brine of the electrolytic cell; the reported values were the average of the results of 6 titration calculations.
The test results for example 2 are given in table 2 below:
TABLE 2 titration test results
| Serial number | V0(mL) | V1(mL) | V2(mL) | V3(mL) | Calculation results (g/L) |
| 1 st time | 11.45 | 7.95 | 25.00 | 500 | 4.97 |
| 2 nd time | 11.50 | 8.00 | 25.00 | 500 | 4.97 |
| 3 rd time | 11.55 | 8.10 | 25.00 | 500 | 4.90 |
| 4 th time | 11.50 | 8.00 | 25.00 | 500 | 4.97 |
| 5 th time | 11.50 | 8.00 | 25.00 | 500 | 4.97 |
| 6 th time | 11.55 | 8.05 | 25.00 | 500 | 4.97 |
| Reporting the value | / | / | / | / | 4.96 |
As can be seen from the detection results in Table 2, the detection method provided by the invention performs titration detection on the sodium chlorate standard solution containing a small amount of free chlorine, and the detection result is 4.96g/L, and the theoretical concentration of sodium chlorate in the sodium chlorate standard solution is 5.00 g/L. The detection result is basically consistent with the theoretical result.
Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (6)
1. A method for detecting chlorate in brine of an electrolytic cell is characterized by comprising the following specific detection steps:
(1) sucking a sample from saline water of an electrolytic cell by a pipette, transferring the sample into a volumetric flask containing 100mL of distilled water, diluting the sample to a scale by the distilled water, and fully shaking up;
(2) sucking 25mL of the liquid obtained in the step (1) from a measuring bottle by using a pipette, transferring the liquid into a 300mL triangular flask, dropwise adding 3% hydrogen peroxide, and continuously detecting by using starch-potassium iodide test paper until the test paper does not change color;
(3) to the solution of step (2) were added 60mL of distilled water and 15mL of H2SO4Adding 25mL0.05mol/L FeSO into the solution by using a burette4Adding 2-5 glass balls into the triangular flask to reactHeating the solution to boil and cooling to room temperature;
(4) 10mL of H was added to the reaction solution of step (3)3PO4The solution was then added with 6 drops of 3g/L sodium diphenylamine sulfonate indicator and the solution was titrated with a potassium dichromate standard: c (1/6K)2Cr2O7) Titrating the solution to be slightly purple at the rate of 0.1mol/L, and repeating the titrating for 6 times; simultaneously, performing a blank test;
(5) substituting each titration parameter into a calculation formula
Calculating the concentration of chlorate in the brine of the electrolytic cell; taking the average value of the calculation results of 6 times of titration as a report value; in the calculation formula:
c0 is the concentration of potassium dichromate standard titration solution, mol/L;
v0 is the volume of the blank potassium dichromate standard titration solution, mL;
v1 is the volume, mL, of the standard titration solution of potassium dichromate consumed by the sample;
v2 is the volume of the sample in step (1), mL;
v3 is the volume of the volumetric flask in the step (1), mL;
106.44 is NaClO3Molar mass of (a), g/mol.
2. The method for detecting chlorate in brine in an electrolytic cell as claimed in claim 1, wherein the volume of the sample in step (1) is 10-25 mL.
3. The method for detecting chlorate in brine in an electrolytic cell as claimed in claim 1, wherein the volume of the volumetric flask in step (1) is 500 mL.
4. The method of claim 1, wherein said H is selected from the group consisting of2SO4The solution was a mixed solution of 1 volume of 98% concentrated sulfuric acid and 1 volume of distilled water.
5. The method of claim 1, wherein said H is selected from the group consisting of3PO4The solution was a mixed solution of 1 volume of 85% phosphoric acid and 1 volume of distilled water.
6. The method of claim 1, wherein the blank test is: accurately measuring 25mL of distilled water by using a pipette, placing the distilled water into a 300mL triangular flask, and accurately measuring 25mL of 0.05mol/L FeSO by using the pipette4Adding the standard solution into a triangular flask, and finally adding 15mL of H2SO4Heating the solution to boiling, cooling to room temperature, and adding 10mL of H3PO4Solution and 6 drops of 3g/L sodium diphenylamine sulfonate indicator, standard titration solution with potassium dichromate: c (1/6K)2Cr2O7) Titrating the solution to be slightly purple at the rate of 0.1 mol/L; the volume of solution using a standard titration of potassium dichromate is recorded.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102745793A (en) * | 2012-07-17 | 2012-10-24 | 浙江华友钴业股份有限公司 | Method for removing free chlorine from solution after cobalt electrolysis |
| CN104310640A (en) * | 2014-10-16 | 2015-01-28 | 杭州电化集团有限公司 | Method for removing free chlorine in chlorine-containing dilute brine generated after brine electrolysis |
| CN104865246A (en) * | 2015-05-20 | 2015-08-26 | 常州大学 | Method for detecting free residual chlorine in drinking water |
| CN107764957A (en) * | 2016-08-16 | 2018-03-06 | 陈飞 | A kind of method for the biochemical oxygen demand (BOD) that can quickly determine in water |
| CN110794084A (en) * | 2019-11-19 | 2020-02-14 | 攀枝花钢企欣宇化工有限公司 | Method for measuring calcium chlorate content |
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- 2020-06-11 CN CN202010530941.1A patent/CN111638211A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102745793A (en) * | 2012-07-17 | 2012-10-24 | 浙江华友钴业股份有限公司 | Method for removing free chlorine from solution after cobalt electrolysis |
| CN104310640A (en) * | 2014-10-16 | 2015-01-28 | 杭州电化集团有限公司 | Method for removing free chlorine in chlorine-containing dilute brine generated after brine electrolysis |
| CN104865246A (en) * | 2015-05-20 | 2015-08-26 | 常州大学 | Method for detecting free residual chlorine in drinking water |
| CN107764957A (en) * | 2016-08-16 | 2018-03-06 | 陈飞 | A kind of method for the biochemical oxygen demand (BOD) that can quickly determine in water |
| CN110794084A (en) * | 2019-11-19 | 2020-02-14 | 攀枝花钢企欣宇化工有限公司 | Method for measuring calcium chlorate content |
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| ZHOUYU120513: "氯酸钠的测定", 《豆丁网》 * |
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