Method for measuring hydrochloric acid bath solution, neutralizing bath solution and analyzing standard titration solution by using automatic potentiometric titrator

Abstract

The invention discloses a method for measuring a hydrochloric acid tank solution, a neutralizing tank solution and analyzing a standard titration solution by using an automatic potentiometric titrator. The method comprises the following steps: S1, preparing a sample solution; s2, calibrating a sample solution; s3, determining a standard titration solution; selecting a sample solution meeting the requirements, wherein the sample solution is a standard titration solution; s4, titration treatment of hydrochloric acid tank liquid or neutralization tank liquid; accurately dropwise adding a calibrated standard titration solution into the hydrochloric acid tank solution or the neutralization tank solution until a titration end point is reached; and S5, measuring the concentration of the hydrochloric acid tank solution or the neutralization tank solution. The titration result of the potentiometric titration mode is not greatly different from the result of the manual titration mode, the potentiometric titration repeatability is good, the potentiometric titration reminds that the end point is advanced by artificial misjudgment by using an electric signal, and meanwhile, the program assists the calculation operation, so that the operation is simpler.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical analysis, and in particular relates to a method for analyzing hydrochloric acid tank solution, neutralization tank solution and standard titration solution by using an automatic potentiometric titrator. Background Art

[0002] Titration is an important chemical analysis technique used to determine the concentration of a specific chemical substance in a solution. Titration is widely used in chemical analysis, especially in situations where the concentration of a substance in a solution needs to be accurately determined, such as pH determination, metal ion determination, etc.

[0003] At present, the chemical laboratory determines the chemical composition of the acid and alkali bath solution by manual titration. The endpoint of the titration is determined by observing the color mutation of the test solution during the titration process with the naked eye. Everyone has different sensitivities to color changes. In particular, the color changes of some titration tests are not particularly obvious (such as using ferrous sulfate to titrate nitric acid in the bath solution. The solution color changes from yellow to brown, which is the titration endpoint and is difficult to determine). This will lead to large differences in test results. Summary of the invention

[0004] The present invention aims to solve the problem that the titration endpoint of the prior art cannot be determined when the color change is not particularly obvious during manual titration, and proposes the following technical solution: Method for analyzing hydrochloric acid bath solution, neutralization bath solution and standard titration solution using automatic potentiometric titrator The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator is to prepare a standard titration solution, and the hydrochloric acid tank solution or the neutralization tank solution is titrated with the prepared standard titration solution, comprising the following steps: S1, preparing sample solution; Dilute the required solution with water, stir and divide into several sample solutions; S2, calibration sample solution; Titrate the sample solution into the calibration solution until the titration endpoint is reached, record the volume of the sample solution consumed, and calculate the concentration of the sample solution; S3, determine the standard titration solution; Select a sample solution that meets the requirements. This sample solution is the standard titration solution. S4, hydrochloric acid tank solution or neutralization tank solution titration treatment; Accurately add the calibrated standard titration solution into the hydrochloric acid tank or neutralization tank until the titration endpoint is reached; S5. Determine the concentration of hydrochloric acid tank solution or neutralization tank solution; Record the volume of sample solution consumed and calculate the concentration of hydrochloric acid bath solution or neutralization bath solution.

[0005] As a preferred embodiment of the above technical solution, an interference test is further provided between the step S1 and the step S2, and the interference test is used to detect whether the sample solution contains elements that react with the hydrochloric acid tank solution, and the interference test includes the following contents: a. Detect elements in sample solution; Detect the presence and concentration of elements in the sample solution and screen out the elements with higher content in the sample solution; b. Conduct interference tests; Add the element with higher content into the standard hydrochloric acid bath solution at 10 times its content, and obtain the hydrochloric acid content in the solution after the reaction; c. Comparative judgment; Compare whether there is a large deviation in the hydrochloric acid content in the salt solution before and after adding the standard hydrochloric acid tank solution: If the hydrochloric acid content in the salt solution has a large deviation, re-prepare it; If there is no significant deviation in the hydrochloric acid content in the salt solution, proceed to step S2.

[0006] As a preferred embodiment of the above technical solution, the required solution includes a hydrochloric acid solution, the hydrochloric acid solution is diluted with water to form a hydrochloric acid sample solution, the calibration solution of the hydrochloric acid sample solution is a sodium carbonate solution, and the hydrochloric acid sample solution that meets the requirements is a hydrochloric acid standard titration solution.

[0007] As a preferred embodiment of the above technical solution, two control groups are set during the hydrochloric acid sample solution calibration process, and a blank control experimental group is set in each of the two control groups.

[0008] As a preferred embodiment of the above technical solution, in the control groups of the hydrochloric acid sample solution calibration process, one control group adopts a potentiometric titration method, and the other control group adopts a manual titration method.

[0009] As a preferred embodiment of the above technical solution, the standard hydrochloric acid titration solution is titrated with the neutralization tank solution, and the measured data in the titration reaction between the standard hydrochloric acid titration solution and the neutralization tank solution is the sodium carbonate content.

[0010] As a preferred embodiment of the above technical solution, two control groups are set during the titration process of the hydrochloric acid standard titration solution and the neutralization tank solution, and a blank control experimental group is set in both control groups.

[0011] As a preferred embodiment of the above technical solution, in the control groups of the titration process of the hydrochloric acid standard titration solution and the neutralization tank solution, one control group adopts a potentiometric titration method, and the other control group adopts a manual titration method.

[0012] As a preferred embodiment of the above technical solution, the required solution includes a sodium hydroxide solution, the sodium hydroxide solution is diluted with water to form a sodium hydroxide sample solution, the calibration solution of the sodium hydroxide sample solution is a potassium hydrogen phthalate solution, and the sodium hydroxide solution that meets the requirements is a sodium hydroxide standard titration solution.

[0013] As a preferred embodiment of the above technical solution, two control groups are set during the calibration process of the sodium hydroxide sample solution, and a blank control experimental group is set in both control groups.

[0014] As a preferred embodiment of the above technical solution, in the control groups of the sodium hydroxide solution calibration process, one control group adopts a potentiometric titration method, and the other control group adopts a manual titration method.

[0015] As a preferred embodiment of the above technical solution, the standard sodium hydroxide titration solution is titrated with the hydrochloric acid tank solution, and in the titration reaction between the standard sodium hydroxide titration solution and the hydrochloric acid tank solution, the measured data is the hydrochloric acid content.

[0016] As a preferred embodiment of the above technical solution, two control groups are set during the titration process of the sodium hydroxide standard titration solution and the hydrochloric acid tank solution, and a blank control experimental group is set in both control groups.

[0017] As a preferred embodiment of the above technical solution, in the control groups of the titration process of the sodium hydroxide standard titration solution and the hydrochloric acid tank solution, one control group adopts a potentiometric titration method, and the other control group adopts a manual titration method.

[0018] As a preferred embodiment of the above technical solution, the potentiometric titration method in the titration experiments in step S2 and step S4 is performed using an automatic potentiometric titrator.

[0019] The beneficial effects of the present invention are: 1. The titration results of potentiometric titration are not much different from those of manual titration, and the potentiometric titration has good repeatability. The potentiometric titration uses electrical signals to remind people to avoid premature end point misjudgment. At the same time, the program assists in calculation and operation, making the operation simpler. 2. When conducting precision tests on hydrochloric acid bath solution and neutralization bath solution, the potentiometric titration method has better precision, smaller and more accurate error values, and better meets the experimental requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a flow chart of an embodiment; Figure 2 Shown is a flow chart of an interference test in an embodiment; DETAILED DESCRIPTION In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings of the specification.

[0021] Example Figure 1 The method of using an automatic potentiometric titrator to measure the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution analysis, preparing the standard titration solution, and using the prepared standard titration solution to titrate the hydrochloric acid tank solution or the neutralization tank solution, is characterized in that it includes the following steps: S1, preparing sample solution; Dilute the required solution with water, stir and divide into several sample solutions; S2, calibration sample solution; Titrate the sample solution into the calibration solution until the titration endpoint is reached, record the volume of the sample solution consumed, and calculate the concentration of the sample solution; S3, determine the standard titration solution; Select a sample solution that meets the requirements. This sample solution is the standard titration solution. S4, hydrochloric acid tank solution or neutralization tank solution titration treatment; Accurately add the calibrated standard titration solution into the hydrochloric acid tank or neutralization tank until the titration endpoint is reached; S5. Determine the concentration of hydrochloric acid tank solution or neutralization tank solution; Record the volume of sample solution consumed and calculate the concentration of hydrochloric acid bath solution or neutralization bath solution.

[0022] During the operation, transfer 2.00ml of the solution to be tested to a 150ml beaker, add water to dilute the solution to 50ml, then put the solution to be tested into the automatic potentiometric titrator. According to the parameters of the 916 Ti-Touch automatic potentiometric titrator, use hydrochloric acid solution (about 0.1mol / L) and sodium hydroxide solution (about 0.1mol / L) to automatically titrate the hydrochloric acid tank solution and the neutralization tank solution. After the reaction reaches the end point, record the milliliters of the hydrochloric acid standard solution and the sodium hydroxide standard solution used for titration, and use the formula to calculate the content of hydrochloric acid and sodium carbonate in the solution to be tested: HClg / L= Where: C—concentration of sodium hydroxide standard solution, unit: mol / L; V1—sodium hydroxide consumption, unit: mL; V2—Volume of the tank liquid taken out, unit: mL; 36.5—Molar mass of HCl in g / mol.

[0023] Na (g / L) = In the formula: C---concentration of hydrochloric acid mol / L; V1---mL of hydrochloric acid consumed; V2---Sample volume 106--- Na 2 CO 3 Molecular weight.

[0024] Titration is an important chemical analysis technique used to determine the concentration of a specific chemical substance in a solution. It can be categorized into the following: 1. Acid-base titration It is a titration analysis method based on the proton transfer reaction between acid and base.

[0025] It can be used to determine acids, bases and amphoteric substances. Its basic reaction is H + +OH - =H 2 O.

[0026] 2. Complexometric titration (complexometric titration analysis) It is a titration analysis method based on coordination reaction.

[0027] It can be used to measure metal ions. If EDTA is used as a complexing agent, the reaction is: + represents metal ions, Y 4- Represents the anion of EDTA.

[0028] 3. Redox titration It is a titration analysis method based on redox reaction.

[0029] It can be used to determine substances with redox properties or certain substances without redox properties, such as the potassium dichromate method for determining iron, the reaction is as follows: Cr 2 O7 2- +6Fe 2+ +14H + =2 Cr 3 ++6Fe 3+ +7H 2 O.

[0030] 4. Precipitation titration It is a titration analysis method based on precipitation reaction. + , CN - 、SCN - and halogen-like plasmas, such as the silver titration method, the reaction is as follows: Ag + +Cl - = AgCl.

[0031] In this technical solution, an acid-base titration method is adopted.

[0032] When using titration, the following methods can be used: (1) Direct titration method: Any reaction that meets the requirements of titration analysis can be directly titrated with the substance to be tested using a standard titration solution.

[0033] For example, NaOH standard titration solution can be used to directly titrate samples such as HCl and H2SO4.

[0034] (2) Back titration method: The back titration method (also known as the back titration method) is to accurately add an appropriate excess of standard solution to the test solution. After the reaction is complete, another standard solution is used to back titrate the remaining first standard solution to determine the content of the component to be tested.

[0035] This titration method is mainly used for situations where the titration reaction speed is slow or the reactant is solid. After adding the standard titration solution that meets the stoichiometric relationship, the reaction often cannot be completed immediately. For example, the reaction speed of Al3+ ions and EDTA (a complexing agent) solution is slow and cannot be titrated directly. The back titration method can be used. (3) Displacement titration: The displacement titration method is to first add an appropriate reagent to react quantitatively with the component to be measured to generate another titratable substance, then use a standard solution to titrate the reaction product, and then calculate the content of the component to be measured based on the relationship between the consumption of the titrant, the substance generated by the reaction, and the amount of the component to be measured.

[0036] This titration method is mainly used for determinations that cannot be titrated directly because the titration reaction has no quantitative relationship or is accompanied by side reactions. 2 Cr 2 O 7 Calibration Na 2 S 2 O 3 The concentration of the solution is a certain amount of K 2 Cr 2 O 7 In acidic solution, it reacts with excess KI to precipitate a considerable amount of I 2 , starch as indicator, Na 2 S 2 O 3 I precipitated by titration of solution 2 , and then obtain Na 2 S 2 O 3 The concentration of the solution.

[0037] (4) Indirect titration method: Some components to be tested cannot react directly with the titrant, but their content can be indirectly determined through other chemical reactions.

[0038] For example, Ca in solution 2+ Almost no redox reaction occurs, but it is used to react with C 2 O 4 2- CaC 2 O 4 After precipitating, filter and wash, add H 2 SO 4 Dissolve it with KMnO 4 Titration of C with standard titration solution 2 O 4 2- , Ca can be indirectly determined 2+ content.

[0039] In this technical solution, a direct titration method is adopted.

[0040] An interference test is also provided between step S1 and step S2, and the interference test is used to detect whether the sample solution contains elements that react with the hydrochloric acid tank solution, and the interference test includes the following contents: a. Detect elements in sample solution; Detect the presence and concentration of elements in the sample solution and screen out the elements with higher content in the sample solution; b. Conduct interference tests; Add the element with higher content into the standard hydrochloric acid bath solution at 10 times its content, and obtain the hydrochloric acid content in the solution after the reaction; c. Comparative judgment; Compare whether there is a large deviation in the hydrochloric acid content in the salt solution before and after adding the standard hydrochloric acid tank solution: If the hydrochloric acid content in the salt solution has a large deviation, re-prepare it; If there is no significant deviation in the hydrochloric acid content in the salt solution, proceed to step S2.

[0041] In this technical solution, an inductively coupled plasma emission spectrometer (ICP) model iCAPPRO is used to detect the components in the sample solution. The inductively coupled plasma emission spectrometer (ICP) uses the high-temperature plasma generated by inductively coupled plasma (ICP) to excite the atomic emission spectrum in the sample, and determines the presence and concentration of elements in the sample by analyzing these spectral lines.

[0042] In the sample solution, the contents of phosphorus, copper, vanadium, silicon, manganese, tantalum, calcium and other components are relatively low, and it can be considered that they have no effect on the determination process of hydrochloric acid. Therefore, these components are not considered as factors affecting the determination process of hydrochloric acid. The contents of nickel, chromium, aluminum, titanium, iron and other components are slightly higher in the solution to be tested, and their content data are shown in the following table: Table 2 Interfering element content For the above five components with higher content, in order to verify their interference, these five elements were added to the standard solution with 10 times their content, namely aluminum: 50ug / mL, nickel: 130ug / mL, chromium: 90ug / mL, iron: 80g / mL, titanium: 40ug / mL, and the hydrochloric acid bath sample was measured using an inductively coupled plasma emission spectrometer. The test results are shown in Table 3.

[0043] Table 3 Interference test results (g / L) From the data in Table 3, it can be seen that the deviation of the hydrochloric acid content before and after adding the standard solution is less than 1g / L, which shows that the automatic potentiometric titration method for determining the hydrochloric acid content is not affected by other elements.

[0044] The inductively coupled plasma emission spectrometer is mainly composed of a high-frequency transmitter, a peristaltic pump sampling system, a light source, a spectroscopic system, a detector (CID), a cooling system and data processing. Its working principle mainly involves the formation of a plasma source by generating current as an energy source through electromagnetic induction of a time-varying magnetic field. This process includes several key steps: 1. High frequency current generates electromagnetic field: A high-frequency electromagnetic field is generated in the induction coil by a high-frequency current, which ionizes the working gas (such as argon) to form a high-temperature plasma with flame-like discharge. The maximum temperature of this plasma can reach 10,000K.

[0045] 2. Introduction of sample solution: The sample solution enters the nebulizer through the inlet capillary and the peristaltic pump and is atomized into an aerosol state. Subsequently, the aerosol is introduced into the high-temperature plasma by the carrier gas.

[0046] 3. Evaporation, atomization, excitation and ionization: In plasma, the sample solution is heated to a high temperature, causing it to evaporate, atomize, excite, and ionize. During this process, the elements in the sample exist in the form of atoms or ions and generate radiation.

[0047] 4. Spectral analysis: The emitted light passes through the light-collecting tube and enters the slit, reflector, prism, chelle grating and collimator to form a two-dimensional spectrum. The spectrum falls on the CID detector with 540×540 pixels in the form of a spot, and each spot covers several pixels. The spectrometer measures the concentration of elements by measuring the number of photons falling on the pixels. The photon number signal is then converted into a digital signal through a circuit and displayed on a computer or the result is printed out by a printer.

[0048] The method of using inductively coupled plasma emission spectrometer (ICP) is: 1. Sample processing: Samples usually need to go through appropriate pretreatment steps, such as dissolution, dilution or conversion into a form that is easy to analyze, in order to facilitate entry into the ICP.

[0049] 2. Inductively coupled plasma (ICP): In ICP-OES, the sample solution passes through a plasma nozzle in a high-frequency inductively coupled plasma (ICP). Under the action of a high-frequency electric field, the gas (usually argon) is ionized and forms a high-temperature plasma.

[0050] This high-temperature plasma (usually reaching 10,000 to 100 million K) can effectively excite the atoms in the sample, causing them to emit specific spectral lines.

[0051] 3. Spectral measurement: The emitted spectrum is collected by an optical system and dispersed into spectral lines of different wavelengths.

[0052] Spectral lines are measured by a photodiode array (or single-channel photodiode), which detects the intensity of light at different wavelengths.

[0053] 4. Data Analysis: By comparing the spectrum in the sample with a library of spectra of known standards, the concentration of each element is determined.

[0054] The required solution includes a sodium hydroxide solution, the sodium hydroxide solution is diluted with water to form a sodium hydroxide sample solution, the calibration solution of the sodium hydroxide sample solution is a potassium hydrogen phthalate solution, and the sodium hydroxide solution that meets the requirements is a sodium hydroxide standard titration solution.

[0055] During the calibration process of the sodium hydroxide sample solution, two control groups are set, and a blank control experimental group is set in each of the two control groups.

[0056] Among the control groups in the sodium hydroxide solution calibration process, one control group adopts a potentiometric titration method, and the other control group adopts a manual titration method.

[0057] The standard sodium hydroxide titration solution is titrated with the hydrochloric acid tank solution. During the titration reaction between the standard sodium hydroxide titration solution and the hydrochloric acid tank solution, the measured data is the hydrochloric acid content.

[0058] Two control groups are set during the titration process of the sodium hydroxide standard titration solution and the hydrochloric acid tank solution, and a blank control experimental group is set in each of the two control groups.

[0059] In the control groups of the titration process of the sodium hydroxide standard titration solution and the hydrochloric acid tank solution, one control group adopts the potentiometric titration method, and the other control group adopts the manual titration method.

[0060] Sodium hydroxide standard titration solution titration comparison: The preparation method of standard titration solution is as per GB / T601 Chemical Reagents - Preparation of Standard Titration Solution, Section 4.1. Take 0.1 mol / L sodium hydroxide standard titration solution as an example: Add 100 mL of carbon dioxide-free distilled water into a test tube, then weigh 110 grams of sodium hydroxide and dissolve it in the distilled water. Shake the test tube to evenly distribute the sodium hydroxide in the distilled water to prepare a sodium hydroxide solution. Pour the prepared sodium hydroxide solution into a polyethylene container and place it in a sealed container until the sodium hydroxide solution is observed to be clear.

[0061] Use a plastic pipette to transfer 5.4 mL of the supernatant to a 1000 mL volumetric flask, dilute with carbon dioxide-free distilled water until the distilled water level reaches the corresponding scale, shake the volumetric flask to allow the solution to diffuse quickly and evenly disperse, and then transfer the solution to a polyethylene container. At this time, the concentration of the solution is about 0.1 mol / L.

[0062] Weigh 3 portions of potassium hydrogen phthalate (about 0.75 g), place them in 250 mL conical flasks, add 50 mL of carbon dioxide-free distilled water to dissolve, and titrate with the prepared sodium hydroxide standard solution to the titration endpoint, and record the volume of sodium hydroxide standard solution consumed at this time. Perform a blank test at the same time.

[0063] Using potassium hydrogen phthalate for calibration, the reaction formula is: KHC 8 H 4 O 4 +NaOH=KNaC 8 H 4 O 4 +H 2 O.

[0064] In this reaction, sodium hydroxide reacts with potassium benzoate, the hydroxide ion (OH-) of the sodium hydroxide combines with the hydrogen ion (H+) of the potassium benzoate to produce water, and the potassium salt of benzoic acid (KNaC8H4O4) is formed.

[0065] The 0.1 mol / L sodium hydroxide standard titration solution was calibrated using manual titration and potentiometric titration. The results are as follows: Table 4 Potentiometric titration results of standard titration solution Table 5 Manual titration results of standard titration solution The concentration of the sodium hydroxide standard solution determined by manual titration is 0.1014 mol / L, and the concentration of the sodium hydroxide standard solution determined by potentiometric titration is 0.1011 mol / L. The titration values ​​of the two methods are not much different. The repeatability of manual titration is greater than that of potentiometric titration, indicating that the precision of potentiometric titration is better.

[0066] Determination of hydrochloric acid content in hydrochloric acid tank liquid: Use the calibrated sodium hydroxide standard titration solution to titrate the hydrochloric acid bath solution: accurately transfer 2.00mL of the hydrochloric acid bath solution into a 300mL conical flask, dilute it to 70mL with water, and use manual titration and potentiometric titration to determine the hydrochloric acid content in the hydrochloric acid bath solution. The results are as follows: Table 8 Comparison of the determination of hydrochloric acid content in hydrochloric acid tank solution by manual titration and potentiometric titration It can be seen from Table 8 that the manual titration result is 207.63 g / L, and the potentiometric titration result is 207.74 g / L, both of which meet the measurement range requirements. However, the repeatability of the potentiometric titration is 0.006%, which is much smaller than the manual titration's 0.027%, indicating that the potentiometric titration has better stability.

[0067] The required solution includes a hydrochloric acid solution, the hydrochloric acid solution is diluted with water to form a hydrochloric acid sample solution, the calibration solution of the hydrochloric acid sample solution is a sodium carbonate solution, and the hydrochloric acid sample solution that meets the requirements is a hydrochloric acid standard titration solution.

[0068] During the hydrochloric acid sample solution calibration process, two control groups are set, and a blank control experimental group is set in each of the two control groups.

[0069] In the control groups of the hydrochloric acid sample solution calibration process, one control group adopts a potentiometric titration method, and the other control group adopts a manual titration method.

[0070] The standard hydrochloric acid titration solution is titrated with the neutralization tank solution, and the measured data in the titration reaction between the standard hydrochloric acid titration solution and the neutralization tank solution is the sodium carbonate content.

[0071] Two control groups are set during the titration process of the hydrochloric acid standard titration solution and the neutralization tank solution, and a blank control experimental group is set in each of the two control groups.

[0072] In the control groups of the titration process of the hydrochloric acid standard titration solution and the neutralization tank solution, one control group adopts a potentiometric titration method, and the other control group adopts a manual titration method.

[0073] Titration comparison of hydrochloric acid standard titration solution: The preparation method of standard titration solution is as per GB / T601 Chemical Reagents - Preparation of Standard Titration Solution, 4.1. Take 0.1mol / L hydrochloric acid standard titration solution as an example: Pipette 9 mL of hydrochloric acid into a 1000 mL volumetric flask and dilute to volume with carbon dioxide-free water. The concentration of the solution is about 0.1 mol / L.

[0074] Using sodium carbonate for calibration, the reaction formula is: Na 2 CO 3 +2HCl=2NaCl+H 2 O+CO 2 .

[0075] In this reaction, sodium carbonate and hydrochloric acid react to form sodium chloride and water while releasing carbon dioxide gas.

[0076] Weigh about 0.2g of sodium carbonate in 3 portions, place them in 250mL conical flasks, add 50mL of water to dissolve, and titrate with the prepared hydrochloric acid standard solution to the titration endpoint, record the volume at this point, and perform a blank test at the same time.

[0077] The 0.1 mol / L hydrochloric acid standard titration solution was calibrated using manual titration and potentiometric titration. The results are as follows: Table 6 Potentiometric titration results Table 7 Manual titration results The average value of 8 times of potentiometric titration is 0.1013 mol / L, and the result of 8 times of manual titration is 0.1008 mol / L. The titration values ​​of the two methods are not much different. The repeatability of manual titration is greater than that of potentiometric titration, which shows that the precision of potentiometric titration is better.

[0078] Determination of sodium carbonate content in the neutralization tank: Use the calibrated hydrochloric acid standard titration solution to titrate the neutralization tank solution. Accurately transfer 2 mL of the neutralization tank solution to a 200 mL conical flask, add 75 mL of carbon dioxide-free water, and use manual titration and potentiometric titration to determine the sodium carbonate content in the neutralization tank solution. The results are as follows: Table 9 Comparison of manual titration and potentiometric titration for determination of sodium carbonate content in neutralization tank solution As shown in Table 9, the manual titration result is 52.70 g / L, and the potentiometric titration result is 53.26 g / L. The potentiometric titration value is higher than the manual titration value, and the difference between the two methods is 0.56 g / L, indicating that the manual titration has an early end point misjudgment. Therefore, the potentiometric titration method is significantly better than the manual titration method and has good repeatability.

[0079] Precision test: A portion of chromium from the hydrochloric acid bath solution and the neutralization bath solution was selected and each was measured 11 times according to the test method. The average value and relative standard deviation were calculated and the results are shown in Table 10.

[0080] Table 10 Precision test results It can be seen from Table 10 that the relative standard deviations of the 11 measurements of sodium carbonate in the hydrochloric acid bath and the neutralization bath by the self-potentiometric titration method are 0.013% and 0.012%, respectively. The precision of the method is good.

[0081] The potentiometric titration method in the titration experiments in step S2 and step S4 both uses an automatic potentiometric titrator to perform the titration operation.

[0082] In this technical solution, the device for obtaining the concentration of the substance to be tested or the end point of the reaction is a 916Ti-Touch automatic potentiometric titrator, and its parameters are shown in Table 1: Table 1 Parameters of 916 Ti-Touch Automatic Potentiometric Titrator Potentiometric titration is an analytical method that uses a potentiometer to measure the change in electrode potential to determine the extent of a chemical reaction. Usually, a potentiometer is connected to the electrode and the concentration of the analyte in the solution or the endpoint of the reaction is determined by recording the change in potential. The implementation steps are: 1. Preparation: Select the appropriate electrode (usually a glass electrode), reference electrode, and potentiometric equipment. Select the appropriate titration reagent and indicator based on the analytical goal.

[0083] 2. Titration process: Slowly drip the titration reagent into the solution to be tested, and record the potential change displayed by the potentiometer. When the potential displayed by the potentiometer changes steadily, it indicates that the reaction has reached the end point, which is usually the point where the potential changes most dramatically, or the point where the color of the indicator changes significantly.

[0084] The amount of reagent added at this time can be used to calculate the concentration of the substance to be tested in the solution or the endpoint of the reaction.

[0085] 3. Data processing: Calculate the required concentration or endpoint data based on the titration curve or graphical analysis of potential changes.

[0086] 4. Computational analysis: The concentration of the substance to be tested or the endpoint of the reaction is calculated based on the concentration and consumption of the titration reagent and the potential change data recorded during the titration process.

[0087] In the potentiometric titration experiment, some key calculation formulas need to be used, as shown below: 1. Standard electrode potential formula: E = E° - [RT / (nF)]ln[a(ion concentration)] Among them, E represents the electrode potential to be measured, E° represents the standard electrode potential, R represents the ideal gas constant, T represents the temperature, n represents the number of electron transfers, F represents the Faraday constant, and a represents the ion activity.

[0088] 2. Potential change formula at the titration endpoint: ΔE=RT / nF×ln(c1 / c2) Wherein, ΔE represents the potential change during the titration process, R, T, n, and F have the same meanings as above, c1 represents the concentration of the standard solution, and c2 represents the solute concentration in the solution to be titrated.

[0089] Use the above formula to calculate the required parameters.

[0090] The operating steps of the automatic potentiometric titrator are: 1. Sample preparation: Prepare the test solution and ensure that its concentration and volume meet the experimental requirements. Place the test solution in the reaction chamber of the titrator.

[0091] 2. Set the experimental parameters: Turn on the instrument and set the starting and ending potentials of the titration, as well as the titration rate and the temperature of the solution. These parameters are usually set according to the specific experiment and the specifications of the instrument.

[0092] 3. Start titration: Start the titration process. The automatic potentiometric titrator will control the addition rate of the titrant according to the set parameters and record the potential change of the reaction solution in real time during the titration process.

[0093] 4. Observe and record: During the titration process, the instrument will display the current potential change curve or value. Observe the change of potential and stop the titration when the set endpoint potential is reached.

[0094] 5. Data processing: Analyze and record the potential value or curve at the end of the titration. These data can be used to calculate the concentration of the target analyte in the test solution or determine the reaction endpoint.

[0095] 6. Cleaning and Closure: After the titration, clean the electrode and other parts of the instrument promptly to prevent contamination and damage. Turn off the instrument and store it properly.

[0096] The manual titration method is manual titration with visual observation. It usually includes the following basic steps: 1. Solution preparation: Prepare the test solution to ensure that its concentration and volume meet the requirements of the analysis. The test solution usually needs to be appropriately diluted so that a clear endpoint change can be observed during the titration.

[0097] 2. Indicator selection: Depending on the nature of the analyte in the solution to be tested, an appropriate indicator is selected. An indicator is a chemical substance that can show a color change during the titration process and usually reacts chemically with the analyte to indicate the titration endpoint.

[0098] 3. Titration operation: Using a burette with a relatively accurate volume, a standardized titrant (called titration reagent) is added drop by drop to the solution to be tested. During the titration process, the container needs to be gently shaken to mix the reaction and ensure that the reaction is uniform.

[0099] 4. Observation endpoint: Continue titrating and record the amount of titrant added until a distinct color change or change in the indicator solution is observed. This change usually indicates the endpoint of the titration, indicating that the reaction has been completely completed.

[0100] 5. Calculation results: Based on the known concentration of the titrant and the amount consumed during the titration, the concentration of the analyte in the test solution is calculated. This usually involves using the chemical equation for the titration reaction and the molarity of the titrant to perform the calculation.

[0101] 6. Data processing and recording: Record relevant data at the beginning and end of the titration, including the initial and final volumes of the titrant, and the amount of titrant consumed.

[0102] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them.

Claims

1. A method for analyzing hydrochloric acid tank solution, neutralization tank solution and standard titration solution by using an automatic potentiometric titrator to prepare a standard titration solution, and titrate the hydrochloric acid tank solution or the neutralization tank solution with the prepared standard titration solution, characterized in that: The following steps are involved: S1, preparing sample solution; Dilute the required solution with water, stir and divide into several sample solutions; S2, calibration sample solution; Titrate the sample solution into the calibration solution until the titration endpoint is reached, record the volume of the sample solution consumed, and calculate the concentration of the sample solution; S3, determine the standard titration solution; Select a sample solution that meets the requirements. This sample solution is the standard titration solution. S4, hydrochloric acid tank solution or neutralization tank solution titration treatment; Accurately add the calibrated standard titration solution into the hydrochloric acid tank or neutralization tank until the titration endpoint is reached; S5. Determine the concentration of hydrochloric acid tank solution or neutralization tank solution; Record the volume of sample solution consumed and calculate the concentration of hydrochloric acid bath solution or neutralization bath solution.

2. The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator according to claim 1, characterized in that: An interference test is also provided between step S1 and step S2, and the interference test is used to detect whether the sample solution contains elements that react with the hydrochloric acid tank solution, and the interference test includes the following contents: a. Detect elements in sample solution; Detect the presence and concentration of elements in the sample solution, and screen out the elements with higher content in the sample solution; b. Conduct interference tests; Add the element with higher content into the standard hydrochloric acid bath solution at 10 times its content, and obtain the hydrochloric acid content in the solution after the reaction; c. Comparative judgment; Compare whether there is a large deviation in the hydrochloric acid content in the salt solution before and after adding the standard hydrochloric acid tank solution: If the hydrochloric acid content in the salt solution has a large deviation, re-prepare it; If there is no significant deviation in the hydrochloric acid content in the salt solution, proceed to step S2.

3. The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator according to claim 1, characterized in that: The required solution includes a hydrochloric acid solution, the hydrochloric acid solution is diluted with water to form a hydrochloric acid sample solution, the calibration solution of the hydrochloric acid sample solution is a sodium carbonate solution, and the hydrochloric acid sample solution that meets the requirements is a hydrochloric acid standard titration solution.

4. The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator according to claim 3, characterized in that: Two control groups are set in the hydrochloric acid sample solution calibration process, and blank control experimental groups are set in both control groups. Among the control groups in the hydrochloric acid sample solution calibration process, one control group adopts potentiometric titration and the other control group adopts manual titration.

5. The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator according to claim 3, characterized in that: The standard hydrochloric acid titration solution is titrated with the neutralization tank solution, and during the titration reaction between the standard hydrochloric acid titration solution and the neutralization tank solution, the measured data is the sodium carbonate content.

6. The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator according to claim 6, characterized in that: Two control groups are set in the titration process of the standard hydrochloric acid solution and the neutralization tank solution, and blank control experimental groups are set in both control groups. Among the control groups in the titration process of the standard hydrochloric acid solution and the neutralization tank solution, one control group adopts potentiometric titration and the other control group adopts manual titration.

7. The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator according to claim 1, characterized in that: The required solution includes a sodium hydroxide solution, the sodium hydroxide solution is diluted with water to form a sodium hydroxide sample solution, the calibration solution of the sodium hydroxide sample solution is a potassium hydrogen phthalate solution, and the sodium hydroxide solution that meets the requirements is a sodium hydroxide standard titration solution.

8. The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator according to claim 7, characterized in that: Two control groups are set in the sodium hydroxide sample solution calibration process, and blank control experimental groups are set in both control groups. Among the control groups in the sodium hydroxide solution calibration process, one control group adopts potentiometric titration and the other control group adopts manual titration.

9. The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator according to claim 8, characterized in that: The standard sodium hydroxide titration solution is titrated with the hydrochloric acid tank solution. During the titration reaction between the standard sodium hydroxide titration solution and the hydrochloric acid tank solution, the measured data is the hydrochloric acid content.

10. The method for analyzing the hydrochloric acid tank solution, the neutralization tank solution and the standard titration solution by using an automatic potentiometric titrator according to claim 9, characterized in that: Two control groups are set in the titration process of the sodium hydroxide standard titration solution and the hydrochloric acid tank solution, and a blank control experimental group is set in both control groups. Among the control groups in the titration process of the sodium hydroxide standard titration solution and the hydrochloric acid tank solution, one control group adopts a potentiometric titration method, and the other control group adopts a manual titration method.

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