Method for distinguishing Zn < 2 + > and Ce < 3 + >
Through the 'glyoxal-Na2SO3-Na2S2O5-EDTA' pH clock system, the pH change map was recorded, and Zn2+ and Ce3+ were distinguished according to the degree of final stable pH drop, which solved the problem of low analytical sensitivity in the prior art, and achieved simple and fast qualitative analysis.
Patent Information
- Application Number
- CN202510533361.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-26
- Publication Date
- 2025-07-18
AI Technical Summary
When distinguishing between Zn2+ and Ce3+, especially for complex matrix samples, the analysis sensitivity is low and the operation is complicated, and there is a lack of simple and fast detection methods.
The 'glyoxal-Na2SO3-Na2S2O5-EDTA' pH clock system is used as the distinguishing solution. By recording the pH spectrum with time, the qualitative distinction between Zn2+ and Ce3+ is achieved according to the degree of the final stable pH drop of the sample to be distinguished.
A qualitative analysis method with high accuracy and easy operation is provided, which can effectively distinguish Zn2+ and Ce3+ in the range of 18-23°C, and the concentration range is 3.636×10-3mol/L-6.061×10-3mol/L significantly differentiate well.
Smart Images
Figure CN120334315A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a discrimination method. Specifically, a "glyoxal - Na2SO3 - Na2S2O5 - EDTA" pH clock system is established. According to the different degrees of decrease in the finally stabilized pH value of the pH clock system by the samples to be discriminated, the discrimination of the samples to be discriminated is realized, belonging to the field of analytical chemistry. Background Art
[0002] Zinc sulfate, with the molecular formula ZnSO4, is the most important zinc salt. It is a colorless rhombic crystal or white powder. It is the main raw material for manufacturing lithopone and zinc salts, and can also be used as a mordant in dyeing and printing, a preservative for wood and leather, and an important auxiliary raw material for producing viscose fiber and vinylon fiber. In addition, it is also used in electroplating and electrolysis industries, and can be used to manufacture cables. In industry, cooling water is the largest amount of water used. The cooling water in a closed - loop cooling system should not corrode or scale the metal, so it needs to be treated, and this process is called water quality stabilization. Zinc sulfate is used as a water quality stabilizer here.
[0003] Cerium(III) sulfate, with the molecular formula Ce2(SO4)3, is a colorless or white crystalline powder. It is commonly used as an oxidant, catalyst, and decolorizer. In organic chemistry, cerium(III) sulfate can be used to oxidize organic substances such as alcohols, ethers, aldehydes, and ketones. Cerium(III) sulfate is irritating. Skin, eyes, and respiratory tract contact should be avoided. Appropriate protective equipment, such as laboratory gloves, glasses, and masks, should be worn during operation. If contact occurs accidentally, immediately rinse with a large amount of clean water. Contact with strong oxidants, reducing agents, and combustible substances should be avoided to prevent dangerous reactions. When disposing of waste cerium(III) sulfate, it should be treated according to local regulations and should not be discharged randomly.
[0004] Zn 2+ and Ce 3+ The determination of Zn and Ce mainly adopts instrumental analysis methods, such as ion chromatography, atomic absorption spectrometry, etc. Chromatography has the advantages of high sensitivity and good accuracy, but for samples with complex matrices, the analysis sensitivity decreases. Therefore, it is very necessary to find a detection and analysis method with good detection effect and simple and rapid operation. Summary of the Invention
[0005] The present invention aims at Zn 2+ and Ce 3+A novel, convenient and fast differentiation method is provided, that is, a method for qualitatively detecting a sample solution to be differentiated using the "glyoxal - Na2SO3 - Na2S2O5 - EDTA" pH clock system as the differentiation solution. This method is based on the different sensitive responses of this pH clock system to different metal ions. Specifically, the "glyoxal - Na2SO3 - Na2S2O5 - EDTA" pH clock reaction system is used as the differentiation solution, and the graph of pH change with time is recorded; after the pH clock system reaction stabilizes, at 300 s, equal - volume and same - concentration sample solutions to be differentiated containing Zn 2+ and Ce 3+ are added to two groups of pH clock systems respectively. According to the different degrees of decrease in the pH value at which the pH clock system finally stabilizes caused by the sample solution to be differentiated, the qualitative differentiation of the sample solution to be differentiated is realized.
[0006] The difference between this qualitative differentiation method and the prior art is that in this invention, the "glyoxal - Na2SO3 - Na2S2O5 - EDTA" pH clock system is used as the differentiation solution. According to the different degrees of decrease in the pH value at which the pH clock system finally stabilizes caused by the sample solution to be differentiated, the differentiation of the sample solution to be differentiated is realized: If, after adding the sample solution to be differentiated, compared with the graph of pH change with time without adding the sample solution to be differentiated, the decrease in the pH value at which the clock system finally stabilizes is smaller, then the added sample solution to be differentiated is a sample containing Zn 2+ ; if, after adding the sample solution to be differentiated, the decrease in the pH value at which the clock system finally stabilizes is larger, then the added sample solution to be differentiated is a sample containing Ce 3+ sample; When the sample solution to be differentiated is detected in the differentiation solution (pH clock system), the temperature of the pH clock system is controlled within any specific temperature in the range of 18 - 23 °C.
[0007] Zn 2+ and Ce 3+ The distinguishable concentration range in the differentiation solution (pH clock system) is 3.636×10 -3 mol / L - 6.061×10 -3 mol / L.
[0008] The distinguishable concentration range of the above - mentioned sample solution to be differentiated is the optimal concentration range determined through experiments. Within this concentration range, the differences in the effects of Zn 2+ and Ce 3+ on this differentiation solution are very obvious, easy to observe and analyze, and easy to achieve differentiation. In addition, the concentration ranges of each component in the differentiation solution (pH clock system) are shown in Table 1, and the best solution of the differentiation solution (pH clock system) obtained through multiple experiments is shown in Table 2: Table 1: Concentrations of each component in the pH clock system
[0009] Table 2: Optimal Concentrations of Components in the pH Clock System
[0010] The specific experimental steps are as follows: 1. Prepare 33 mL of the differentiating solution (pH clock system) within the concentration range specified in Table 1, and control its temperature at a specific constant value between 18 - 23 °C. Insert the prepared working electrode (pH combination electrode, Leici, E-331) into the solution. Connect the other end of the working electrode to a computer via a potential / temperature / pH comprehensive tester (Jiaxing Disheng Electronic Technology Co., Ltd., ZHFX-595). After setting the acquisition time and sampling rate in the chemical signal acquisition and analysis program on the computer, quickly click the start button to monitor the pH of the solution. The computer records the curve of the pH of the clock system changing with time, that is, the pH clock pattern. When detecting a substance, after the pH clock system reaction stabilizes, quickly add the substance to be detected at 300 s, and record the pH clock pattern of the pH changing with time in the same way.
[0011] The basic parameters of the pH clock pattern include: pH jump range: The pH corresponding to the start of the pH jump to the pH corresponding to the end of the pH jump.
[0012] The final stable pH value of the pH clock system: The pH value corresponding to when the pH enters the stable state after the end of the pH jump. Description of the Drawings
[0013] Figure 1 It is the pattern of the pH value of the differentiating solution (pH clock system) changing with time in Example 1 when no sample to be differentiated is added.
[0014] Figure 2 It is the pattern of the pH value of the differentiating solution (pH clock system) changing with time in Example 1 after adding 3.636×10 -3 mol / L Zn 2+ solution.
[0015] Figure 3 It is the pattern of the pH value of the differentiating solution (pH clock system) changing with time in Example 1 after adding 3.636×10 -3 mol / L Ce 3+ solution.
[0016] Figure 4 It is the pattern of the pH value of the differentiating solution (pH clock system) changing with time in Example 2 when no sample to be differentiated is added.
[0017] Figure 5 In Example 2, after adding 4.848×10 -3 mol / L Zn 2+ solution, the graph showing the change of the pH value of the solution (pH clock system) with time was distinguished.
[0018] Figure 6 In Example 2, after adding 4.848×10 -3 mol / L Ce 3+ solution, the graph showing the change of the pH value of the solution (pH clock system) with time was distinguished.
[0019] Figure 7 In Example 3, when no sample to be distinguished was added, the graph showing the change of the pH value of the solution (pH clock system) with time was distinguished.
[0020] Figure 8 In Example 3, after adding 6.061×10 -3 mol / L Zn 2+ solution, the graph showing the change of the pH value of the solution (pH clock system) with time was distinguished.
[0021] Figure 9 In Example 3, after adding 6.061×10 -3 mol / L Ce 3+ solution, the graph showing the change of the pH value of the solution (pH clock system) with time was distinguished. Detailed implementation mode Example 1
[0022] In this example, the feasibility of the distinguishing method of the present invention for Zn 2+ and Ce 3+ was verified as follows: (1) Prepare the distinguishing solution First, prepare a mixed solution of 0.88 mol / L glyoxal solution, 0.05 mol / L Na2SO3, 0.125 mol / L Na2S2O5 and 5×10 -3 mol / L EDTA with distilled water respectively. Add 10 mL of distilled water, 20 mL of 0.05 mol / L Na2SO3, 0.125 mol / L Na2S2O5 and 5×10 -3mol / L EDTA solution, 3mL 0.88 mol / L glyoxal solution, to ensure that the concentrations of the components in the "glyoxal-Na2SO3- Na2S2O5-EDTA" pH clock system are glyoxal 0.08 mol / L, Na2SO3 0.03030 mol / L, Na2S2O5 0.07576 mol / L, EDTA 3.030×10 -3 mol / L, the total volume was 33 mL, and the temperature was controlled at 20°C.
[0023] At the same time, distilled water was used as the solvent to prepare 0.3 mol / L concentration of Zn 2+ and Ce 3+ The sample solution to be differentiated.
[0024] (2) Obtaining pH clock map The graph of the pH value of the prepared differentiation solution (pH clock system) changing with time is recorded by a computer equipped with a chemical signal acquisition and analysis program (without adding the sample to be tested). Figure 1 As shown, the final pH was about 8.85 as a blank control. Two sets of differentiation solutions were prepared with the same concentration of each component as the above differentiation solution. For one of the sets, after the pH clock system reaction stabilized, 400 μL of 0.3 mol / L Zn was added to 33 mL of the pH clock system at 300 s using a pipette. 2+ The sample solution was prepared so that its concentration in the differentiating solution was 3.636 × 10 -3 mol / L, added Zn 2+ The solution makes the final stable pH of the system about 8.63, such as Figure 2 As shown; for the other group, after the pH clock system reaction was stable, 400 μL of 0.3 mol / L Ce was added to 33 mL of the pH clock system with a pipette at 300 s. 3+ Sample solution, making Ce 3+ The concentration in the differentiated solution is 3.636×10 -3 mol / L, added Ce 3+ The final stable pH of the system is about 8.18. Figure 3 shown.
[0025] (3) Differentiation According to the sample Zn 2+ and Ce 3+ The pH clock system finally stabilizes the pH value at different levels, which enables qualitative analysis of the samples to be differentiated. Figure 1 , Figure 2 , Figure 3 It can be seen that Zn 2+The addition of the solution, compared with the graph of the change of pH value with time when the sample to be detected is not added, the final stable pH value of the clock system decreases less; the addition of Ce 3+ results in a greater decrease in the final stable pH value of the clock system. From the above experiments, it can be seen that by comparing the different degrees of decrease in the final stable pH value of the clock system, Zn 2+ and Ce 3+ can be distinguished.
[0026] Take two pre-prepared solutions of the samples to be distinguished at 0.3 mol / L (one is a Zn 2+ solution, and the other is a Ce 3+ solution, but the two have not been distinguished yet), mark one of them as sample 1 and the other as sample 2; prepare two sets of distinguishing solutions with the same component concentrations as above, and add 400 μL of 0.3 mol / L sample 1 and sample 2 respectively, so that their concentrations in the distinguishing solution are 3.636×10 -3 mol / L.
[0027] Analysis and comparison show that the addition of sample 1 results in a smaller decrease in the final stable pH value of the pH clock system (the degree of decrease in the final stable pH corresponds to Figure 2 and does not correspond to Figure 3 ), while the addition of sample 2 results in a greater decrease in the final stable pH value of the pH clock system (the degree of decrease in the final stable pH corresponds to Figure 3 and does not correspond to Figure 2 ). Therefore, sample 1 is a Zn 2+ solution, sample 2 is a Ce 3+ solution, thus realizing the distinction between Zn 2+ and Ce 3+ . Example 2
[0028] This example verifies the feasibility of the method for distinguishing Zn 2+ and Ce 3+ of the present invention according to the following steps: (1) Prepare the distinguishing solution First, use distilled water to prepare a mixed solution of 0.88 mol / L glyoxal solution, 0.05 mol / L Na2SO3, 0.125 mol / L Na2S2O5 and 5×10 -3 mol / L EDTA. Add 9 mL of distilled water, 20.8 mL of 0.05 mol / L Na2SO3, 0.125 mol / L Na2S2O5 and 5×10 -3A mixed solution of EDTA at [mol / L], 3.2 mL of glyoxal solution at 0.88 mol / L, to ensure that the concentrations of each component in the "glyoxal - Na2SO3 - Na2S2O5 - EDTA" pH clock system are glyoxal 0.08533 mol / L, Na2SO3 0.03152 mol / L, Na2S2O5 0.07879 mol / L, and EDTA 3.152×10 -3 mol / L, with a total volume of 33 mL, and the temperature is controlled at 20 °C.
[0029] Meanwhile, using distilled water as the solvent, prepare sample solutions to be distinguished with a concentration of 0.4 mol / L containing Zn 2+ and Ce 3+ .
[0030] (2) Obtain the pH clock graph The graph of the change in the pH value of the prepared distinguishing solution (pH clock system) over time is recorded by a computer equipped with a chemical signal acquisition and analysis program (without adding the sample to be detected). As Figure 4 shown, the final pH is approximately 8.84 for the blank control. Prepare another two groups of distinguishing solutions with the same component concentrations as the above-mentioned distinguishing solution. For one group, after the pH clock system reaction stabilizes, at 300 s, use a pipette to add 400 μL of 0.4 mol / L Zn 2+ solution sample solution to the 33 mL pH clock system, so that its concentration in the distinguishing solution is 4.848×10 -3 mol / L. The added Zn 2+ solution makes the final stable pH of the system approximately 8.46, as Figure 5 shown; for the other group, after the pH clock system reaction stabilizes, at 300 s, use a pipette to add 400 μL of 0.4 mol / L Ce 3+ sample solution to the 33 mL pH clock system, so that the concentration of Ce 3+ in the distinguishing solution is 4.848×10 -3 mol / L. The added Ce 3+ makes the final stable pH of the system approximately 7.88, as Figure 6 shown.
[0031] (3) Distinguish Based on the different degrees of decrease in the final stable pH value of the pH clock system caused by the samples to be distinguished, Zn 2+ and Ce 3+ , qualitative analysis of the samples to be distinguished is achieved. By comparing Figure 4 , Figure 5 , Figure 6 It can be seen that Zn2+ The addition of the solution, compared with the graph of the change of pH value with time when the sample to be detected is not added, the final stable pH value of the clock system decreases less; Ce 3+ The addition of results in a greater decrease in the final stable pH value of the clock system. From the above experiments, it can be seen that by comparing the different degrees of decrease in the final stable pH value of the clock system, Zn 2+ and Ce 3+ can be distinguished.
[0032] Take two pre-prepared solutions of the samples to be distinguished at 0.4 mol / L (one is the Zn 2+ solution, and the other is the Ce 3+ solution, but the two have not been distinguished yet), mark one of them as sample 1 and the other as sample 2; prepare two sets of distinguishing solutions with the same component concentrations as above, and add 400 μL of 0.4 mol / L sample 1 and sample 2 respectively, so that their concentrations in the distinguishing solution are 4.848×10 -3 mol / L.
[0033] Analysis and comparison show that: the addition of sample 1 results in a smaller decrease in the final stable pH value of the pH clock system, (the degree of decrease in the final stable pH corresponds to Figure 5 and does not correspond to Figure 6 ), while the addition of sample 2 results in a greater decrease in the final stable pH value of the pH clock system (the degree of decrease in the final stable pH corresponds to Figure 6 and does not correspond to Figure 5 ). Therefore, sample 1 is the Zn 2+ solution, sample 2 is the Ce 3+ solution, thus realizing the distinction between Zn 2+ and Ce 3+ . Example 3
[0034] This example verifies the feasibility of the method for distinguishing Zn 2+ and Ce 3+ of the present invention according to the following steps: (1) Prepare the distinguishing solution First, prepare a mixed solution of 0.88 mol / L glyoxal solution, 0.05 mol / L Na2SO3, 0.125 mol / L Na2S2O5 and 5×10 -3 mol / L EDTA with distilled water respectively. Add 12 mL of distilled water, 18.2 mL of 0.05 mol / L Na2SO3, 0.125 mol / L Na2S2O5 and 5×10 -3A mixed solution of EDTA at [mol / L], 2.8 mL of glyoxal solution at 0.88 mol / L, to ensure that the concentrations of each component in the "glyoxal - Na2SO3 - Na2S2O5 - EDTA" pH clock system are glyoxal 0.07467 mol / L, Na2SO3 0.02758 mol / L, Na2S2O5 0.06894 mol / L, and EDTA 2.758×10 -3 mol / L, with a total volume of 33 mL, and the temperature is controlled at 20 °C.
[0035] Meanwhile, using distilled water as the solvent, prepare sample solutions to be distinguished with a concentration of 0.5 mol / L of Zn 2+ and Ce 3+ .
[0036] (2) Obtain the pH clock diagram The diagram of the change in the pH value of the prepared distinguishing solution (pH clock system) over time is recorded by a computer equipped with a chemical signal acquisition and analysis program (without adding the sample to be detected). As Figure 7 shown, the final pH is approximately 8.87 for blank control. Prepare another two groups of distinguishing solutions with the same component concentrations as the above-mentioned distinguishing solution. For one group, after the pH clock system reaction stabilizes, at 300 s, use a pipette to add 400 μL of 0.5 mol / L Zn 2+ solution sample solution to the 33 mL pH clock system, so that its concentration in the distinguishing solution is 6.061×10 -3 mol / L. The added Zn 2+ solution makes the final stable pH of the system approximately 8.38, as Figure 8 shown; for the other group, after the pH clock system reaction stabilizes, at 300 s, use a pipette to add 400 μL of 0.5 mol / L Ce 3+ sample solution to the 33 mL pH clock system, so that the concentration of Ce 3+ in the distinguishing solution is 6.061×10 -3 mol / L. The added Ce 3+ makes the final stable pH of the system approximately 7.28, as Figure 9 shown.
[0037] (3) Distinguish Based on the different degrees of decrease in the final stable pH value of the pH clock system caused by the samples to be distinguished, Zn 2+ and Ce 3+ , qualitative analysis of the samples to be distinguished is achieved. By comparing Figure 7 , Figure 8 , Figure 9 It can be seen that Zn2+ When the solution is added and compared with the pH value-time change graph without adding the sample to be detected, the final stable pH value of the clock system decreases less; for the addition of Ce 3+ , the final stable pH value of the clock system decreases more. From the above experiments, it can be seen that by comparing the different degrees of decrease in the final stable pH value of the clock system, the distinction between Zn 2+ and Ce 3+ can be achieved.
[0038] Take two pre-prepared solutions of the samples to be distinguished at 0.5 mol / L (one is the Zn 2+ solution, and the other is the Ce 3+ solution, but they have not been distinguished yet). Mark one of them as sample 1 and the other as sample 2; prepare two sets of distinguishing solutions with the same component concentrations as above, and add 400 μL of 0.5 mol / L sample 1 and sample 2 respectively, so that their concentrations in the distinguishing solution are 6.061×10 -3 mol / L.
[0039] Analysis and comparison show that: the addition of sample 1 makes the final stable pH value of the pH clock system decrease less (the degree of decrease in the final stable pH corresponds to Figure 8 and does not correspond to Figure 9 ), while the addition of sample 2 makes the final stable pH value of the pH clock system decrease more (the degree of decrease in the final stable pH corresponds to Figure 9 and does not correspond to Figure 8 ). Therefore, sample 1 is the Zn 2+ solution, and sample 2 is the Ce 3+ solution, thus achieving the distinction between Zn 2+ and Ce 3+ .
Claims
1. A method for distinguishing Zn 2+ and Ce 3+ is characterized in that: Prepare a sample solution to be distinguished of Zn 2+ and Ce 3+ using distilled water as the solvent; Apply the "glyoxal - Na2SO3 - Na2S2O5 - EDTA" pH clock reaction system as a differentiating solution, and record the graph of the change in the pH value of the clock system over time; The temperature of the pH clock system is controlled at any specific temperature within the range of 18 - 23 °C; after the reaction of the pH clock system is stable, equal volumes of sample solutions with the same concentration of Zn 2+ and Ce 3+ to be distinguished are added to two groups of pH clock systems respectively. According to the different degrees of decrease in the final stable pH value of the pH clock system caused by the samples to be distinguished, the samples to be distinguished are distinguished: if, after adding the sample solution to be distinguished, compared with the pH-time change pattern without adding the sample solution to be distinguished, the final stable pH value of the clock system decreases less, then the added sample to be distinguished is the sample containing Zn 2+ ; if, after adding the sample solution to be distinguished, the final stable pH value of the clock system decreases more, then the added sample to be distinguished is the sample containing Ce 3+ sample; The molar concentration ranges for the components in the solution are as follows: glyoxal 0.06933 - 0.09067 mol / L, Na2SO3 0.02697 - 0.03212 mol / L, Na2S2O5 0.06742 - 0.08030 mol / L, EDTA 2.697×10 -3 - 3.212×10 -3 mol / L.
2. The method according to claim 1, wherein: The molar concentrations of the components in the solution are distinguished as 0.08 mol / L of glyoxal, 0.03030 mol / L of Na2SO3, 0.07576 mol / L of Na2S2O5, and 3.030×10 -3 mol / L of EDTA.
3. The method according to claim 1, wherein: The distinguishable concentration range of the sample to be distinguished in the distinguishing solution is 3.636×10 -3 mol / L - 6.061×10 -3 mol / L.
4. The method according to claim 1, wherein: The temperature of the clock system is controlled at 20°C.