阅读说明：本技术 基于碘量法测定过氧一硫酸盐、过氧二硫酸盐和过氧化氢混合溶液中各过氧化物浓度的方法 (Method for determining concentrations of peroxides in mixed solutions of peroxomonosulfate, peroxodisulfate and hydrogen peroxide based on iodometry ) 是由 关英红 张天禹 欧照凡 付强 于 2019-11-13 设计创作，主要内容包括：基于碘量法测定过氧一硫酸盐、过氧二硫酸盐和过氧化氢混合溶液中各过氧化物浓度的方法,它涉及基于碘量法测定过氧一硫酸盐、过氧二硫酸盐和过氧化氢混合溶液中各过氧化物浓度的方法。本发明的目的是为了解决现有方法无法测定三种氧化剂混合物中三种氧化剂各自浓度的问题,本发明方法为：取待测液加入碳酸氢钠和碘化钾,静置后加入冰乙酸,滴定,计算得到氧化剂浓度和。另取待测液加入磷酸一氢钠-磷酸二氢钠缓冲液和过氧化氢酶溶液,再加入碳酸氢钠和碘化钾,静置加入冰乙酸,滴定,得PMS、PDS浓度和；再取待测液加入磷酸一氢钠-磷酸二氢钠缓冲液和过氧化氢酶,加入碘化钾和乙酸-乙酸钠缓冲液,静置后滴定,计算得PMS浓度。本发明应用于氧化剂浓度测定领域。(A method for determining the concentration of each peroxide in a mixed solution of peroxymonosulfate, peroxydisulfate and hydrogen peroxide based on an iodometric method relates to a method for determining the concentration of each peroxide in a mixed solution of peroxymonosulfate, peroxydisulfate and hydrogen peroxide based on an iodometric method. The invention aims to solve the problem that the concentration of each of three oxidants in a mixture of the three oxidants cannot be measured by the existing method, and the method comprises the following steps: and adding sodium bicarbonate and potassium iodide into the solution to be detected, standing, adding glacial acetic acid, titrating, and calculating to obtain the oxidant concentration sum. Adding a sodium monohydrogen phosphate-sodium dihydrogen phosphate buffer solution and a catalase solution into the solution to be detected, adding sodium bicarbonate and potassium iodide, standing, adding glacial acetic acid, and titrating to obtain the concentration sum of PMS and PDS; and adding a sodium monohydrogen phosphate-sodium dihydrogen phosphate buffer solution and catalase into the solution to be detected, adding potassium iodide and an acetic acid-sodium acetate buffer solution, standing, titrating, and calculating to obtain the concentration of PMS. The method is applied to the field of oxidant concentration determination.)

1. A method for determining the concentration of each peroxide in a mixed solution of peroxomonosulfate, peroxodisulfate and hydrogen peroxide on the basis of iodometry, characterized in that the method is carried out as follows:

taking x mL of solution to be detected, adding sodium bicarbonate and potassium iodide, shaking, standing for 15-20min, adding glacial acetic acid, shaking, and using concentration c₀Titrating a mol/L sodium thiosulfate solution, taking starch as an indicator, titrating the solution until the solution is colorless, and recording the dosage h of the sodium thiosulfate₁ mL；

Adding sodium monohydrogen phosphate-sodium dihydrogen phosphate buffer solution and catalase solution into the to-be-detected solution x mL, shaking, standing for 5-10min, adding sodium bicarbonate and potassium iodide, shaking, standing for 15-20min, adding glacial acetic acid, and adding the solution with concentration of c₀Titrating a mol/L sodium thiosulfate solution, taking starch as an indicator, titrating the solution until the solution is colorless, and recording the dosage h of the sodium thiosulfate₂ mL；

Thirdly, taking x mL of the solution to be detected, adding sodium monohydrogen phosphate-sodium dihydrogen phosphate buffer solution and catalase solution, shaking up, standing for 5-10min, sequentially adding potassium iodide and acetic acid-sodium acetate buffer solution with the pH value of 3, shaking up, standing for 2-5min, and then using the solution with the concentration of c₀Titrating a mol/L sodium thiosulfate solution, taking starch as an indicator, and titrating the solutionUntil colorless, recording the dosage h of the sodium thiosulfate₃ mL；

Wherein the concentration c of peroxymonosulfate in the solution to be tested₁＝(h₃*c₀) 2 x; peroxodisulfate concentration c₂＝[(h₂-h₃)*c₀]2 x; hydrogen peroxide concentration c₃＝[(h₁-h₂)*c₀]2 x; wherein h is₁、h₂、h₃The unit is mL; c. C₀、c₁、c₂、c₃The unit is mol/L.

2. The method for iodometry-based determination of the concentrations of peroxides in a mixed solution of peroxymonosulfate, peroxydisulfate, and hydrogen peroxide as claimed in claim 1, wherein the concentrations of potassium iodide and sodium bicarbonate in the solutions tested in step one and step two are both 1.81mol/L and 0.79mmol/L, respectively.

3. The method for iodometry-based determination of the concentration of each peroxide in a mixed solution of peroxomonosulfate, peroxodisulfate and hydrogen peroxide as claimed in claim 1, wherein the ratio by volume of glacial acetic acid to the test solution in the first and second steps is 3.3 (100- "101").

4. The iodometry-based method for determining the concentration of each peroxide in a mixed solution of peroxymonosulfate, peroxydisulfate, and hydrogen peroxide as claimed in claim 1, wherein the volume ratio of the sodium monohydrogen phosphate-sodium dihydrogen phosphate buffer to the test solution in the second step and the third step is 1:100, and the volume ratio of the catalase solution to the test solution is 1: 500.

5. The iodometry-based method for determining the concentration of each peroxide in a mixed solution of peroxymonosulfate, peroxydisulfate and hydrogen peroxide as claimed in claim 1, wherein the volume ratio of the acetic acid-sodium acetate buffer to the test solution in step three is 1: 20.

6. The method for iodometry-based determination of the concentrations of peroxides in a mixed solution of peroxymonosulfate, peroxydisulfate and hydrogen peroxide as claimed in claim 1, wherein the concentration of potassium iodide in the test solution of step three is 0.06mol/L or more.

7. The method for iodometry-based determination of the concentrations of peroxides in a mixed solution of peroxymonosulfate, peroxydisulfate, and hydrogen peroxide as claimed in claim 1, wherein the concentration of sodium monohydrogen phosphate in said sodium monohydrogen phosphate-sodium dihydrogen phosphate buffer is 0.039 mol/L; the concentration of sodium dihydrogen phosphate is 0.070 mol/L.

8. The iodometry-based method for determining the concentrations of peroxides in a mixed solution of peroxymonosulfate, peroxydisulfate, and hydrogen peroxide as set forth in claim 1, wherein the catalase solution has a concentration of 5g/L or more and a catalase activity of 2000-5000 units/mg.

9. The iodometry-based method for determining the concentration of each peroxide in a mixed solution of peroxymonosulfate, peroxydisulfate and hydrogen peroxide as set forth in claim 1, wherein the starch indicator is made from 0.5g of soluble starch and 100mL of distilled water.

Technical Field

The invention relates to a method for determining the concentration of each peroxide in a mixed solution of peroxomonosulfate, peroxodisulfate and hydrogen peroxide on the basis of the iodometric method.

Background

Peroxymonosulfate (PMS), Peroxydisulfate (PDS), and hydrogen peroxide (H)₂O₂) Is widely used as a strong oxidant in the treatment process of drinking water and waste water. The three oxidants are activated to generate sulfate radicals and/or hydroxyl radicals with strong oxidizability, so that organic pollutants are more effectively oxidized and degraded. When using the peroxomonosulfate and peroxodisulfate technologies, two other peroxides may be generated in the system. And in the combined technology of the persulfate (PMS/PDS) and the hydrogen peroxide, the persulfate and the hydrogen peroxide exist at the same time. Therefore, it is very important to establish a method for conveniently and rapidly determining the concentration of each oxidant in the peroxide mixed solution. At present, the existing iodometry based on a spectrophotometer or a titration method can only measure the concentration of the single peroxide, but cannot measure the concentration of various oxidants in a mixture in which three peroxides exist simultaneously.

Disclosure of Invention

The invention aims to solve the problem that the concentration of each of three oxidants in a mixed solution of three peroxides cannot be measured by the conventional method, and provides a method for measuring the concentration of each peroxide in the mixed solution of peroxymonosulfate, peroxydisulfate and hydrogen peroxide based on an iodometric method.

The invention relates to a method for measuring the concentration of each peroxide in a mixed solution of peroxymonosulfate, peroxydisulfate and hydrogen peroxide based on an iodometric method, which comprises the following steps:

taking x mL of solution to be detected, adding sodium bicarbonate and potassium iodide, shaking, standing for 15-20min, adding glacial acetic acid, shaking, and using concentration c₀Titrating a mol/L sodium thiosulfate solution, taking starch as an indicator, titrating the solution until the solution is colorless, and recording the dosage h of the sodium thiosulfate₁ mL；

Adding sodium monohydrogen phosphate-sodium dihydrogen phosphate buffer solution and catalase solution into the to-be-detected solution x mL, shaking, standing for 5-10min, adding sodium bicarbonate and potassium iodide, shaking, standing for 15-20min, adding glacial acetic acid, and adding the solution with concentration of c₀ mol/LTitrating the sodium thiosulfate solution, taking starch as an indicator, titrating the solution until the solution is colorless, and recording the dosage h of the sodium thiosulfate₂ mL；

Thirdly, taking x mL of the solution to be detected, adding sodium monohydrogen phosphate-sodium dihydrogen phosphate buffer solution and catalase solution, shaking up, standing for 5-10min, sequentially adding potassium iodide and acetic acid-sodium acetate buffer solution with the pH value of 3, shaking up, standing for 2-5min, and then using the solution with the concentration of c₀Titrating the solution of sodium thiosulfate in mol/L, titrating the solution to be colorless by taking starch as an indicator, and recording the using amount h of the sodium thiosulfate₃ mL；

Wherein the concentration c of peroxymonosulfate in the solution to be tested₁＝(h₃*c₀) 2 x; peroxodisulfate concentration c₂＝[(h₂-h₃)*c₀]2 x; hydrogen peroxide concentration c₃＝[(h₁-h₂)*c₀]2 x; wherein h is₁、h₂、h₃The unit is mL; c. C₀、c₁、c₂、c₃The unit is mol/L.

The invention has the beneficial effects that:

iodometry is a method of analyzing iodine by utilizing the oxidizing property of iodine and the reducing property of iodide ions. Under certain conditions, the iodide ions can reduce corresponding oxidants to generate equivalent iodine, and then sodium thiosulfate standard solution is used for titrating the iodine. Obtaining PMS, PDS and H₂O₂The three oxidant concentrations are combined. The reaction formula is as follows: i is₂+2S₂O₃ ^2-＝2I-+S₄O₆ ^2-+2I^-。

In the invention, the catalase can remove the hydrogen peroxide in the mixed solution and does not influence the reaction of iodide ions and other two oxidants; meanwhile, under the condition of pH 3 acetic acid-sodium acetate buffer solution, PDS hardly reacts with iodide ions, so that the concentration of PMS in the solution to be detected can be determined; and further determining the corresponding concentrations of the three oxidants according to the concentration summation relationship of the three oxidants. The lowest concentration of each oxidant in the liquid to be detected can be detected to be 0.003mmol/L by the detection method.

Drawings

FIG. 1 shows the measurement of PMS, PDS, H alone in example 1₂O₂Comparing the theoretical concentration and the actual measured concentration of the solution; wherein a is the theoretical concentration; b is the actual measured concentration;

FIG. 2 shows the measurement of PMS, PDS, H in example 2₂O₂A comparison graph of the theoretical concentration of the oxidant and the actual measured concentration of the mixed solution; wherein a is the theoretical concentration; b is the actual measured concentration;

FIG. 3 is a graph comparing the concentrations of the oxidant, PMS and PDS, and the theoretical values measured before and after catalase is added to the three peroxide mixtures of example 2; wherein b is a measured value before adding catalase, c is a measured value after adding catalase, and d is the concentration and theoretical value of PDS and PMS in the mixed solution;

FIG. 4 is a graph comparing the concentration of oxidant measured in example 3 with the theoretical concentration of PMS; wherein a is the actually measured oxidant concentration in the mixed solution; b is a PMS concentration theoretical value.

Detailed Description