A method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution

Abstract

The present invention relates to the field of detection and analysis of the components of pine bark solution, and particularly to a method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution, comprising the following steps: S1, preparing a sample; S2, for two alkaline samples to be measured with the same concentration, titrating them respectively with a potassium permanganate standard solution and an ammonium ferrous sulfate solution, and recording the volume V2 of the consumed potassium permanganate standard solution and the volume V1 of the consumed ammonium ferrous sulfate solution; for a pure water sample, titrating it with a potassium permanganate standard solution, and recording the volume V3 of the consumed potassium permanganate standard solution when the titration is completed; S3, calculating the contents of potassium manganate, potassium permanganate and the total potassium permanganate. The present invention adopts mathematical thinking to solve the problem of quickly and accurately determining the contents of potassium permanganate and potassium manganate in pine bark solution in industry. Through formula design, the combined amount of potassium permanganate and potassium manganate expressed in terms of total potassium permanganate can be obtained, and the contents of potassium manganate and potassium permanganate can also be measured separately.

Description

Technical Field

[0001] The present invention relates to the field of detection and analysis of the components of pine bark solution, and specifically to a method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution. Background Art

[0002] High-temperature alloys and stainless steel materials are widely used in the aviation, automotive, and shipping industries. During the processing and use, metal oxides often form on the material surface under the influence of high temperature, reducing the surface quality of the material and affecting subsequent material detection. To eliminate the adverse effects, a method of heating and soaking in pine bark solution is usually adopted.

[0003] Currently, there is no standard method to detect the component contents of potassium permanganate and potassium manganate in pine bark solution. It is difficult to control the contents of each component of potassium permanganate and potassium manganate, the utilization rate of the bath solution is low, and there is a large waste. Moreover, the existing methods require precipitation separation, which has cumbersome steps, a long cycle, and inconvenient operation. Summary of the Invention

[0004] Aiming at the waste problem of potassium permanganate and potassium manganate when using pine bark solution to treat metal oxides in the prior art, the present invention provides a method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution.

[0005] The present invention is realized through the following technical solutions:

[0006] A method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution, comprising the following steps:

[0007] S1, preparing samples, the samples including an alkaline sample to be measured and a pure water sample;

[0008] S2, for two alkaline samples to be measured with the same concentration, respectively titrating with a potassium permanganate standard solution with a concentration of C2 and an ammonium ferrous sulfate solution with a concentration of C1, and recording the volume V2 of the potassium permanganate standard solution consumed when the titration is completed and the volume V1 of the ammonium ferrous sulfate solution consumed;

[0009] For the pure water sample, titrating with a potassium permanganate standard solution with a concentration of C2, and recording the volume V3 of the potassium permanganate standard solution consumed when the titration is completed;

[0010] S3, calculating the contents of potassium manganate, potassium permanganate, and the total potassium permanganate respectively according to the volume V2 of the potassium permanganate standard solution consumed, the volume V1 of the ammonium ferrous sulfate solution consumed, and the volume V3 of the potassium permanganate standard solution consumed.

[0011] Preferably, the preparation process of the alkaline sample to be tested is as follows: Weigh (m) g of sodium hydroxide, add V ml of pure water and stir well, then add (1 / 2m) g of potassium permanganate and heat until all the potassium permanganate dissolves to obtain the solution to be tested. Then, take 10 ml of the solution to be tested and place it in a 100-ml volumetric flask, make up the volume to the mark and shake well to obtain the alkaline sample to be tested.

[0012] Preferably, the step of obtaining the volume V1 of the ammonium ferrous sulfate solution consumed is as follows: Add a phosphoric acid solution and a hydrogen peroxide solution to the alkaline sample to be tested with a volume of V4 to form a first mixed solution, and heat and boil the first mixed solution until no bubbles overflow on the liquid surface. Then add a perchloric acid solution to the first mixed solution until no more fumes are emitted from the liquid surface of the first mixed solution. Then cool the first mixed solution, and then add water to dissolve the salts in the first mixed solution. After the salts are completely dissolved, perform secondary cooling, and then add N-phenylanthranilic acid indicator, and titrate with ammonium ferrous sulfate with a concentration of C1 until the solution turns bright green, and record the volume of the ammonium ferrous sulfate solution at this time as V1.

[0013] Preferably, when adding water to dissolve, the temperature of the first mixed solution is 50 - 70 °C.

[0014] Preferably, the temperature at the end of the secondary cooling is 50 - 70 °C.

[0015] Preferably, the step of obtaining the volume V2 of the potassium permanganate standard solution consumed is as follows: Add a sulfuric acid solution and a hydrogen peroxide solution to the alkaline sample to be tested with a volume of V5 in sequence to form a second mixed solution, and then titrate the second mixed solution with the potassium permanganate standard solution until the second mixed solution turns light pink, and record the volume of the potassium permanganate standard solution at this time as V2.

[0016] Preferably, the step of obtaining the volume V3 of the potassium permanganate standard solution consumed when titrating the pure water sample is as follows: Add a sulfuric acid solution and a hydrogen peroxide solution to V5 volume of pure water in sequence, and then titrate the solution with the potassium permanganate standard solution until it turns light pink, and record the volume of the potassium permanganate standard solution at this time as V3.

[0017] Preferably, in S3, the calculation expression for the content of potassium manganate is:

[0018]

[0019] Preferably, in S3, the calculation expression for the content of potassium permanganate is:

[0020]

[0021] Preferably, in S3, the calculation expression for the content of total potassium permanganate is:

[0022]

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] A method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution according to the present invention adopts a mathematical idea, designs a calculation formula by using the chemical reactions of different valence states of manganese to determine the contents of potassium permanganate and potassium manganate in a pine bark solution. This method is accurate and fast, solves a difficult problem in industrial determination, and can more effectively control the content of active ingredients in the solution, improve the efficiency of the bath solution and the product quality.

[0025] The method proposed by the present invention is fast and accurate, the operation process is simple, there is no need to carry out procedures such as precipitation and filtration separation, no equipment is required, the titration end point is obvious and easy to judge; the measurement result is accurate and the method is stable.

[0026] Further, hydrogen peroxide is introduced as a reducing agent into the alkaline sample to be measured, and the excessive hydrogen peroxide is easy to remove, reducing the calculation error. At the same time, perchloric acid oxidizes Mn in a concentrated phosphoric acid medium 2+ Convenient and fast, easy to implement, and the oxidized Mn 3+ is stable and the measurement result is accurate. Specific embodiments

[0027] The following further describes the present invention in detail with specific embodiments, which are explanations of the present invention rather than limitations.

[0028] The present invention discloses a method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution, comprising the following steps:

[0029] S1. Prepare samples, including an alkaline sample to be measured and a pure water sample; the preparation process of the alkaline sample to be measured is as follows: weigh (m) g of sodium hydroxide, add V ml of pure water and stir well, then add (1 / 2m) g of potassium permanganate and heat until all the potassium permanganate is dissolved to obtain a solution to be measured; then take 10 ml of the solution to be measured and place it in a 100-ml volumetric flask, make up the volume to the mark and shake well to obtain the alkaline sample to be measured.

[0030] S2. For two alkaline samples to be measured with the same concentration, titrate them respectively with a potassium permanganate standard solution with a concentration of C2 and an ammonium ferrous sulfate solution with a concentration of C1, and record the volume V2 of the potassium permanganate standard solution consumed and the volume V1 of the ammonium ferrous sulfate solution consumed when the titration is completed;

[0031] The steps for obtaining the volume V1 of the ammonium ferrous sulfate solution consumed are as follows: Add phosphoric acid solution and hydrogen peroxide solution to the alkaline sample to be measured with a volume of V4 to form a first mixed solution, and heat and boil the first mixed solution until no bubbles overflow from the liquid surface; then add perchloric acid solution to the first mixed solution until no more fumes are emitted from the liquid surface of the first mixed solution; then cool the first mixed solution to 50 - 70 °C, and then add water to dissolve the salts in the first mixed solution; when the salts are completely dissolved, cool it to 50 - 70 °C for the second time, and then add N-phenylanthranilic acid indicator, and titrate with ammonium ferrous sulfate with a concentration of C1 until the solution turns bright green, and record the volume of the ammonium ferrous sulfate solution at this time as V1.

[0032] In an acidic solution, potassium manganate undergoes a disproportionation reaction to form potassium permanganate and manganese dioxide:

[0033] 3MnO4 2- +4H + =2MnO4 - +MnO2↓+2H2O

[0034] Potassium permanganate and manganese dioxide are quantitatively reduced to divalent manganese by hydrogen peroxide:

[0035] 2MnO4 - +6H + +5H2O2=2Mn 2+ +5O2↑+8H2O

[0036] MnO2+2H + +H2O2=Mn 2+ +O 2 ↑+2H2O

[0037] The remaining hydrogen peroxide is titrated with potassium permanganate, and the total manganese content expressed in terms of potassium permanganate is calculated based on the hydrogen peroxide consumption.

[0038] In phosphoric acid solution, hydrogen peroxide reduces the higher-valent manganese to Mn 2+ :

[0039] 3MnO4 2- +4H + =2MnO4 - +MnO2↓+2H2O

[0040] 2MnO4 - +6H + +5H2O2=2Mn 2+ +5O2↑+8H2O

[0041] MnO2+2H + +H2O2=Mn 2+ +O2↑+2H2O

[0042] Oxidize Mn with perchloric acid 2+ to Mn 3+ , and titrate with ammonium ferrous sulfate to obtain the total amount of Mn 3+ .

[0043] 8Mn 2+ +8H + +ClO4 - =8Mn 3+ +Cl - +4H2O

[0044] Mn 3+ +Fe 2+ =Mn 2+ +Fe 3+ .

[0045] The steps to obtain the volume V2 of the potassium permanganate standard solution consumed are as follows: In the alkaline sample to be measured with a volume of V5, successively add sulfuric acid solution and hydrogen peroxide solution to form a second mixed solution, and then titrate the second mixed solution with the potassium permanganate standard solution until the second mixed solution shows a light pink color. Record the volume of the potassium permanganate standard solution at this time as V2.

[0046] For the pure water sample, titrate with the potassium permanganate standard solution with a concentration of C2, and record the volume V3 of the potassium permanganate standard solution consumed at the end of the titration; the obtaining steps are as follows: In pure water with a volume of V5, successively add sulfuric acid solution and hydrogen peroxide solution, and then titrate the solution with the potassium permanganate standard solution until it shows a light pink color. Record the volume of the potassium permanganate standard solution at this time as V3.

[0047] S3. Calculate the contents of potassium manganate, potassium permanganate, and total potassium permanganate according to the volume V2 of the potassium permanganate standard solution consumed, the volume V1 of the ammonium ferrous sulfate solution consumed, and the volume V3 of the potassium permanganate standard solution consumed respectively.

[0048] The calculation expression for the content of potassium manganate is:[[]]

[0049]

[0050] In S3, the calculation expression for the content of potassium permanganate is:[[]]

[0051]

[0052] In S3, the calculation expression for the total content of potassium permanganate is:[[]]

[0053]

[0054] Where: C1--Concentration of ammonium ferrous sulfate solution, mol / l;

[0055] V1—the volume of ammonium ferrous sulfate solution consumed for titrating the alkaline sample to be tested, ml;

[0056] c2—the concentration of potassium permanganate standard solution, mol / l;

[0057] V2—the volume of potassium permanganate standard solution consumed for titrating the alkaline sample to be tested, ml;

[0058] V3—the volume of potassium permanganate standard solution consumed for the pure water test, ml;

[0059] V4—the sampling volume of the alkaline sample to be tested when adding phosphoric acid and perchloric acid solutions, ml;

[0060] V5—the sampling volume of the alkaline sample to be tested when adding sulfuric acid and hydrogen peroxide solutions, ml.

[0061] Example

[0062] The following reagents are selected: ① Hydrogen peroxide: 0.3%

[0063] ② Sulfuric acid:

[0064] ③ Potassium permanganate standard solution:

[0065] ④ Ammonium ferrous sulfate solution:

[0066] ⑤ Perchloric acid: Analytically pure

[0067] ⑥ Phosphoric acid: Analytically pure

[0068] ⑦ N-Phenylanthranilic acid: 0.2%

[0069] ⑧ Hydrogen peroxide: 3%

[0070] The specific operation steps of this example are as follows:

[0071] S1: Prepare the sample: Take 1 clean beaker, weigh 6 g of sodium hydroxide, add 50 ml of pure water and stir evenly, add 3 g of potassium permanganate and heat until all the potassium permanganate dissolves. Then take 10 ml of the sample solution and place it in a 100-ml volumetric flask, make up the volume to the mark and shake well to obtain the alkaline sample to be tested.

[0072] S2. Take 20 ml of the alkaline sample to be tested in a conical flask, record the sample volume V4, add 8 ml of phosphoric acid and 10 ml of 3% hydrogen peroxide solution, shake well and heat to boiling until no bubbles overflow (i.e., the excess hydrogen peroxide is completely decomposed). After cooling slightly, add 10 ml of perchloric acid, heat until fuming until the solution changes from colorless to purple and continue fuming until the liquid surface is calm (the excess perchloric acid is completely removed). Remove and cool to 35 °C, add water and shake until the salts are completely dissolved, then cool to room temperature. Then add two drops of N-phenylanthranilic acid indicator and titrate Mn3+ with ammonium ferrous sulfate until it turns bright green, record V1.

[0073] Take 5 ml of the alkaline sample to be tested in a conical flask, record the actual sample volume V5. Add 20 ml of 0.18 mol / L sulfuric acid and 15 ml of 0.3% hydrogen peroxide, titrate with potassium permanganate standard solution until it turns light pink, record V2.

[0074] Add pure water to the conical flask to replace the sample, add 20 ml of 0.18 mol / L sulfuric acid and 15 ml of 0.3% hydrogen peroxide, titrate with potassium permanganate standard solution until it turns light pink, record V3.

[0075] Pipette 10 ml of ammonium ferrous sulfate into a conical flask, add 50 ml of water, titrate the ammonium ferrous sulfate solution with KMnO4 standard solution, and record the concentration C1 of the ammonium ferrous sulfate solution.

[0076] S3. Calculate.

[0077] Let C KMnO4 be X mol / l, C K2MnO4 be Y mol / l

[0078] Then: 5X + 4Y = C2(V3 - V2) / V5

[0079] X + Y = C1V1 / V4

[0080] Solve the above two equations simultaneously to get: X = C2(V3 - V2) / V5 - 4C1V1 / V4

[0081] Y = 5C1V1 / V4 - C2(V3 - V2) / V5

[0082]

[0083]

[0084] The contents of potassium permanganate and potassium manganate expressed in terms of potassium permanganate

[0085]

[0086] A method for determining the content of potassium permanganate and potassium manganate in an alkaline solution in the present invention adopts a mathematical idea, designs a calculation formula by using the chemical reactions of different valence states of manganese to determine the content of potassium permanganate and potassium manganate in the loose bark solution. This method is accurate and rapid, solves a difficult problem in industrial determination, and can more effectively control the content of active ingredients in the solution, improve the efficiency of the bath solution and the product quality.

[0087] The above are only the preferred embodiments of the present invention, and are not used to limit the technical solutions of the present invention. Those skilled in the art should understand that, without departing from the spirit and principle of the present invention, the technical solutions can be modified and replaced simply in several aspects, and these modifications and replacements also fall within the protection scope covered by the claims.

Claims

1. A method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution, characterized in that, It includes the following steps: S1. Prepare samples, where the samples include an alkaline sample to be measured and a pure water sample; S2. For two alkaline samples to be measured with the same concentration, titrate them respectively with a potassium permanganate standard solution with a concentration of C2 and an ammonium ferrous sulfate solution with a concentration of C1, and record the volume V2 of the potassium permanganate standard solution consumed and the volume V1 of the ammonium ferrous sulfate solution consumed when the titration is completed; For the pure water sample, titrate it with a potassium permanganate standard solution with a concentration of C2, and record the volume V3 of the potassium permanganate standard solution consumed when the titration is completed; Among them, the steps for obtaining the volume V1 of the ammonium ferrous sulfate solution consumed are as follows: Add phosphoric acid solution and hydrogen peroxide solution to the alkaline sample to be measured with a volume of V4 to form a first mixed solution, and heat and boil the first mixed solution until no bubbles overflow from the liquid surface; then add perchloric acid solution to the first mixed solution until no more fumes are emitted from the liquid surface of the first mixed solution; then cool the first mixed solution, and then add water to dissolve the salts in the first mixed solution; when the salts are completely dissolved, perform secondary cooling, and then add N-phenylanthranilic acid indicator, and titrate with ammonium ferrous sulfate with a concentration of C1 until the solution turns bright green, and record the volume of the ammonium ferrous sulfate solution at this time as ; The steps for obtaining the volume V2 of the potassium permanganate standard solution consumed are as follows: In the alkaline sample to be measured with a volume of V5, add sulfuric acid solution and hydrogen peroxide solution in sequence to form a second mixed solution, and then titrate the second mixed solution with the potassium permanganate standard solution until the second mixed solution shows a light pink color, and record the volume of the potassium permanganate standard solution at this time as ; The steps for obtaining the volume V3 of the potassium permanganate standard solution consumed when titrating a pure water sample are as follows: Add a sulfuric acid solution and a hydrogen peroxide solution successively to pure water with a volume of V5, and then titrate the solution with the potassium permanganate standard solution until it turns light pink. Record the volume of the potassium permanganate standard solution at this time as ; S3. Calculate the contents of potassium manganate, potassium permanganate and total potassium permanganate respectively according to the volume V2 of the potassium permanganate standard solution consumed, the volume V1 of the ammonium ferrous sulfate solution consumed and the volume V3 of the potassium permanganate standard solution consumed.

2. The method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution according to claim 1, characterized in that, The preparation process of the alkaline sample to be measured is as follows: Weigh (m) g of sodium hydroxide, add V ml of pure water and stir evenly, then add (1 / 2m) g of potassium permanganate and heat until all the potassium permanganate is dissolved to obtain a solution to be measured; Then take 10 ml of the solution to be measured and put it into a 100-ml volumetric flask, make up the volume to the mark and shake well to obtain the alkaline sample to be measured.

3. The method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution according to claim 1, characterized in that, When dissolving with water, the temperature of the first mixed solution is 50 - 70 °C.

4. The method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution according to claim 1, characterized in that, The temperature at the end of the secondary cooling is 50 - 70 °C.

5. The method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution according to claim 1, wherein, In S3, the calculation expression for the content of potassium manganate is: 。 6. The method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution according to claim 1, characterized in that, In S3, the calculation expression for the content of potassium permanganate is: 。 7. The method for determining the contents of potassium permanganate and potassium manganate in an alkaline solution according to claim 1, characterized in that, In S3, the calculation expression for the total content of potassium permanganate is: 。

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