Detection method of solution containing EDTA (Ethylene Diamine Tetraacetic Acid) and complexing metal ions thereof

Abstract

The invention relates to a method for detecting a solution containing EDTA (Ethylene Diamine Tetraacetic Acid) and complexing metal ions thereof, and belongs to the technical field of multi-ion detection in solutions. The method comprises the following steps: adding a precipitant into a solution containing EDTA and complexing metal ions thereof, mixing, performing centrifugal separation, and taking supernate; filtering and diluting the supernate, and detecting by using an ion chromatograph to obtain an ion chromatogram containing EDTA and each metal EDTA complex; the solution containing EDTA and complexing metal ions thereof comes from eluent obtained by eluting heavy metal contaminated soil with EDTA. The detection method provided by the invention has the advantages of simplicity and convenience in operation, high sensitivity, high accuracy and good reproducibility, and can be used for detecting multiple ions such as sulfur ions (S < 2->), chloride ions (Cl <->), EDTA (Ethylene Diamine Tetraacetic Acid) and multiple heavy metal complexes in the solution.

Description

Technical Field

[0001] The invention belongs to the technical field of multi-ion detection in solution, and particularly relates to a detection method for a solution containing EDTA and complexed metal ions thereof. Background Art

[0002] Ethylenediaminetetraacetic acid disalt (abbreviated as EDTA) is widely used as a chelating agent in heavy metal soil pollution treatment, electrochemical polishing, detergents, shampoos, agricultural chemical sprays, water purifiers, pH regulators, anticoagulants, etc., and its advantages are high metal extraction efficiency, and the metal complex formed has high solubility and thermodynamic stability, as well as good recyclability and reusability. In the application process of the above-mentioned EDTA, it is inevitable to produce a solution containing EDTA and its complexed metal ions, wherein the complexed alkali metals, rare earth elements and transition metals include one or more of calcium (Ca), cadmium (Cd), nickel (Ni), copper (Cu), lead (Pb), zinc (Zn), etc. This solution is often treated by adding a precipitant, EDTA often exists in the form of a solution, and the metal is precipitated in the form of a sulfide, thereby achieving separation, re-obtaining EDTA and waste metals, and realizing the recycling of EDTA and the waste utilization of waste metal elements (which can be used for steelmaking, etc.). However, if there is no quantitative analysis of the content of EDTA and its complexed metal ions, it will cause excessive waste of precipitants or insufficient precipitation, which increases the difficulty of EDTA and metal recycling. Therefore, it is necessary to find a simple and rapid detection method to accurately and quickly measure the content of EDTA and its complexed metal ions, so as to scientifically guide the use of precipitants in the actual treatment process and reduce the cost of recycling.

[0003] However, existing methods for detecting EDTA are more widely used in food and medicine. This solution containing EDTA and its complex metal ions, especially those derived from soil leaching fluid, has a complex composition and the ions interfere with each other, making it difficult to detect quickly and accurately. At present, there are few reports on detection methods for solutions containing EDTA and its complex metal polyions. Summary of the invention

[0004] In view of the above problems, the present invention provides a detection method for a solution containing EDTA and its complexed metal ions.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for detecting a solution containing EDTA and its complexed metal ions, comprising:

[0007] Adding a precipitant to a solution containing EDTA and its complexed metal ions, mixing, centrifuging, and taking a supernatant;

[0008] After the supernatant is filtered and diluted, it is detected by ion chromatography to obtain a chromatogram containing an EDTA peak and peaks of various metal EDTA complexes.

[0009] Furthermore, the solution containing EDTA and its complexed metal ions is derived from the elution liquid of EDTA elution of heavy metal contaminated soil.

[0010] Furthermore, the precipitant is one of Na2S, NaHS, CaS and FeS.

[0011] Furthermore, the mobile phase used in the ion chromatograph detection is one of potassium hydroxide solution, sodium hydroxide solution, potassium bicarbonate solution, sodium bicarbonate solution, potassium carbonate solution, and sodium carbonate solution.

[0012] Furthermore, the mobile phase used in the ion chromatograph detection is a potassium hydroxide solution, the concentration of the potassium hydroxide solution is 5 to 45 mM, and the retention time is 0.5 to 2.5 min.

[0013] Furthermore, the mobile phase used in the ion chromatograph detection is potassium hydroxide solution, and when the concentration of the potassium hydroxide solution is 5 mM, the gradient of the mobile phase is controlled to have an end concentration of 15 mM and a retention time of 0.5 min.

[0014] Furthermore, the mobile phase used in the ion chromatograph detection is potassium hydroxide solution, and when the concentration of the potassium hydroxide solution is 15 mM, the gradient of the mobile phase is controlled to have an end concentration of 30 mM and a retention time of 2.5 min.

[0015] Furthermore, the mobile phase used in the ion chromatograph detection is potassium hydroxide solution, and when the concentration of the potassium hydroxide solution is 30 mM, the gradient of the mobile phase is controlled to have an end concentration of 45 mM and a retention time of 2.5 min.

[0016] Furthermore, the mobile phase used in the ion chromatograph detection is potassium hydroxide solution, and when the concentration of the potassium hydroxide solution is 45 mM, the gradient of the mobile phase is controlled to have an end concentration of 5 mM and a retention time of 0.2 min.

[0017] Furthermore, when the ion chromatograph is used for detection, the sample injection speed is 1.0 to 1.5 mL / min.

[0018] Beneficial effects of the present invention:

[0019] The invention provides a detection method for a solution containing EDTA and its complexed metal ions, which has the advantages of simple operation, high sensitivity, high accuracy and good reproducibility, and can be used for the detection of sulfur ions (S 2- ), chloride ion (Cl -), EDTA and various heavy metal complexes and other ion detection.

[0020] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 shows a standard ion chromatogram of different ions according to an embodiment of the present invention;

[0023] Figure 2 The ion chromatograms of solutions containing EDTA and its complexed metal ions at different concentrations of Na2S added according to an embodiment of the present invention are shown. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In an embodiment of the present invention, in order to accurately analyze the test results of the ion chromatograph, the solution containing EDTA and its complexed metal ions is a solution of soil eluent components, and the metal types in the solution containing EDTA and its complexed metal ions are heavy metals such as Pb, Cd, Zn and Cu.

[0026] The parameters of the ion chromatograph used in the examples of the present invention are shown in Table 1.

[0027] Table 1

[0028]

[0029] Example 1

[0030] Preparation of multi-ion standard chromatograms

[0031] (I) Preparation of standard chromatogram of EDTA

[0032] The prepared EDTA standard solution (concentration of 0.1M) was tested by ion chromatography. The test conditions were as follows: the flow gradient was set as shown in Table 2, the standard sample injection speed was 1.0 mL / min, and the standard ion chromatogram of EDTA was obtained as shown in Figure 1 shown.

[0033] Table 2

[0034]

[0035] (II) Preparation of standard chromatogram of single metal complex solution

[0036] The prepared single metal complex standard solution was tested by ion chromatography. The test conditions were as follows: the flow gradient was set as shown in Table 2, the standard sample injection rate was 1.0 mL / min, and the standard ion chromatogram of the single metal complex was obtained as shown in Table 2. Figure 1 shown.

[0037] (III) Preparation of standard chromatogram of precipitant (sodium sulfide)

[0038] The prepared sodium sulfide standard solution (concentration of 0.1M) was tested by ion chromatography. The test conditions were as follows: the mobile phase was potassium hydroxide, the concentration flow gradient control settings were as shown in Table 2, the standard sample injection speed was 1.0 mL / min, and the standard ion chromatogram of sodium sulfide was obtained as shown in Figure 1 shown.

[0039] from Figure 1 The peak shapes and elution times of the EDTA standard chromatogram, Pb-EDTA complex standard chromatogram, Cd-EDTA complex standard chromatogram, Zn-EDTA complex standard chromatogram, Cu-EDTA complex standard chromatogram and Na2S standard chromatogram can be clearly seen.

[0040] Example 2

[0041] Ion chromatography detection method for recovering EDTA and its residual complex metal ion solution:

[0042] Step 1, accurately measure 100mL of composite heavy metal complex (Me-EDTA (Pb-EDTA, Cd-EDTA, Zn-EDTA, Cu-EDTA)) solution (the concentration of each heavy metal complex is 10mM, and the total heavy metal complex concentration is 40mM), initial pH 8, pour into a 250mL conical flask, and add 10mL of 0.1M Na2S solution at the same time, so that the total molar ratio of Na2S to the composite heavy metal is 0.25:1, and then place the mixed solution on a shaker and control the reaction temperature at 2522°C. After oscillating for 1h, pour into a 250mL measuring cylinder and let it stand, centrifuge, and take the supernatant;

[0043] Step 2: After the supernatant is filtered through a 0.45 μm filter membrane, the filtrate is diluted 1000 times and then enters the ion chromatograph for detection. The detection conditions are as follows: the flow phase gradient is set as shown in Table 2, the sample injection speed is at a flow rate of 1.0 mL / min, and the ion chromatograms of generated EDTA and residual Pb-EDTA, Cd-EDTA, Zn-EDTA, and Cu-EDTA are obtained, as shown in FIG. Figure 2 shown.

[0044] By calculating the peak area in the ion chromatogram, the concentrations of residual Pb-EDTA, Cd-EDTA, Zn-EDTA and Cu-EDTA in the solution were 9.91mM, 9.26mM, 14.08mM and 2.95mM, respectively, and the concentration of recovered EDTA was 3.04mM.

[0045] Example 3

[0046] Ion chromatography detection method for recovering EDTA and its residual complex metal ion solution:

[0047] Step 1, accurately measure 100mL of composite heavy metal complex (Me-EDTA (Pb-EDTA, Cd-EDTA, Zn-EDTA, Cu-EDTA)) solution (the concentration of each heavy metal complex is 10mM, and the total heavy metal complex concentration is 40mM), initial pH 8, pour into a 250mL conical flask, and add 10mL of 0.2M Na2S solution at the same time, so that the total molar ratio of Na2S to the composite heavy metal is 0.5:1, place on a shaker, control the reaction temperature at 2522°C, shake the reaction for 1h, pour into a 250mL measuring cylinder, let it stand, centrifuge, and take the supernatant;

[0048] Step 2: After the supernatant is filtered through a 0.45 μm filter membrane, the filtrate is diluted 1000 times and then tested by an ion chromatograph. The test conditions are as follows: the flow gradient is set as shown in Table 2, the sample injection speed is at a flow rate of 1.5 mL / min, and the ion chromatograms of the generated EDTA and the residual Pb-EDTA, Cd-EDTA, Zn-EDTA, and Cu-EDTA complexes are obtained, as shown in FIG. Figure 2 shown.

[0049] By calculating the peak area in the ion chromatogram, the concentrations of residual Pb-EDTA, Cd-EDTA, Zn-EDTA and Cu-EDTA in the solution were 6.34mM, 6.67mM, 10.52mM and 1.78mM, respectively, and the concentration of recovered EDTA was 14.42mM.

[0050] Example 4

[0051] Ion chromatography detection method for recovering EDTA and its residual complex metal ion solution:

[0052] Step 1: Accurately measure 100 mL of a composite heavy metal complex (Me-EDTA (Pb-EDTA, Cd-EDTA, Zn-EDTA, Cu-EDTA)) solution (the concentration of each heavy metal complex is 10 mM, and the total heavy metal complex concentration is 40 mM), with an initial pH of 8, and pour it into a 250 mL conical flask. At the same time, add 10 mL of a 0.4 M Na2S solution to make the total molar ratio of Na2S to the composite heavy metal 1:1, place the solution on a shaker and control the reaction temperature at 2522°C. After oscillating for 1 hour, pour the solution into a 250 mL graduated cylinder and allow it to stand for centrifugation to separate the supernatant.

[0053] Step 2: After the supernatant is filtered through a 0.45 μm filter membrane, the filtrate is diluted 1000 times and then tested by an ion chromatograph. The test conditions are as follows: the flow gradient is set as shown in Table 2, the sample injection speed is at a flow rate of 1.5 mL / min, and the ion chromatograms of generated EDTA and residual Pb-EDTA, Cd-EDTA, and Zn-EDTA are obtained. Figure 2 shown.

[0054] By calculating the peak area in the ion chromatogram, the concentrations of residual Pb-EDTA, Cd-EDTA and Zn-EDTA in the solution were 6.31mM, 5.86mM and 8.79mM, respectively. The concentration of recovered EDTA was 18.73mM, while the concentration of Cu-EDTA was below the detection limit.

[0055] Example 5

[0056] Ion chromatography detection method for recovering EDTA and its residual complex metal ion solution:

[0057] Step 1: Accurately measure 100 mL of a composite heavy metal complex (Me-EDTA (Pb-EDTA, Cd-EDTA, Zn-EDTA, Cu-EDTA)) solution (the concentration of each heavy metal complex is 10 mM, and the total heavy metal complex concentration is 40 mM), with an initial pH of 8, and pour it into a 250 mL conical flask. At the same time, add 10 mL of a 0.8 M Na2S solution to make the total molar ratio of Na2S to the composite heavy metal 2:1, place the solution on a shaker and control the reaction temperature at 2522°C. After oscillating for 1 hour, pour the solution into a 250 mL graduated cylinder and allow it to stand for centrifugation to obtain the supernatant.

[0058] Step 2: After the supernatant is filtered through a 0.45 μm filter membrane, the filtrate is diluted 1000 times and then enters an ion chromatograph for detection. The detection conditions and flow gradient settings are shown in Table 2. The sample injection speed is 1.5 mL / min. The ion chromatograms of the generated EDTA and the residual Cd-EDTA and Zn-EDTA complexes are obtained. Figure 2 shown.

[0059] By calculating the peak area in the ion chromatogram, the concentrations of residual Cd-EDTA and Zn-EDTA in the solution were 0.49 mM and 6.49 mM, respectively, the concentration of recovered EDTA was 32.04 mM, while the concentrations of Cu-EDTA and Pb-EDTA were both below the detection limit.

[0060] Example 6

[0061] Ion chromatography detection method for recovering EDTA and its residual complex metal ion solution:

[0062] Step 1, accurately measure 100mL of composite heavy metal complex (Me-EDTA (Pb-EDTA, Cd-EDTA, Zn-EDTA, Cu-EDTA)) solution (the concentration of each heavy metal complex is 10mM, and the total heavy metal complex concentration is 40mM), initial pH 8, pour into a 250mL conical flask, and add 10mL of 1.6M Na2S solution at the same time, so that the total molar ratio of Na2S to the composite heavy metal is 4:1, place on a shaker, control the reaction temperature at 2522°C, shake the reaction for 1h, pour into a 250mL measuring cylinder, let it stand, centrifuge, and take the supernatant;

[0063] Step 2: After the clear solution is filtered through a 0.45 μm filter membrane, the filtrate is diluted 1000 times and then tested by an ion chromatograph. The test conditions are as follows: the flow gradient is set as shown in Table 2, the sample injection speed is at a flow rate of 1.5 mL / min, and the ion chromatograms of generated EDTA and residual Cd-EDTA, Zn-EDTA, and Na2S are obtained, as shown in FIG. Figure 2 shown.

[0064] By calculating the peak area in the ion chromatogram, the concentrations of residual Cd-EDTA and Zn-EDTA in the solution were 0.42 mM and 0.38 mM, respectively, the concentration of recovered EDTA was 39.03 mM, while the concentrations of Cu-EDTA and Pb-EDTA were both below the detection limit.

[0065] Example 7

[0066] Ion chromatography detection method for recovering EDTA and its residual complex metal ion solution:

[0067] Step 1: Accurately measure 100 mL of a composite heavy metal complex (Me-EDTA (Pb-EDTA, Cd-EDTA, Zn-EDTA, Cu-EDTA)) solution (the concentration of each heavy metal complex is 10 mM, and the total heavy metal complex concentration is 40 mM), with an initial pH of 8, and pour it into a 250 mL conical flask. At the same time, add 10 mL of a 2.0 M Na2S solution to make the total molar ratio of Na2S to the composite heavy metals 5:1, place the solution on a shaker and control the reaction temperature at 2522°C. After oscillating for 1 hour, pour the solution into a 250 mL graduated cylinder and allow it to stand for centrifugation to remove the supernatant.

[0068] Step 2: After the supernatant is filtered through a 0.45 μm filter membrane, the filtrate is diluted 1000 times and then tested by an ion chromatograph. The test conditions are as follows: the flow gradient is set as shown in Table 2, the sample injection speed is 1.5 mL / min, and the ion chromatograms of generated EDTA and residual Zn-EDTA are obtained, as shown in FIG. Figure 2 shown.

[0069] According to the peak area calculation in the ion chromatogram, the residual Zn-EDTA concentration in the solution was 0.25 mM, the recovered EDTA concentration was 39.65 mM, while the concentrations of Cd-EDTA, Cu-EDTA and Pb-EDTA were all below the detection limit.

[0070] contrast Figure 1 and Figure 2 From the peaks in the chromatogram in , it can be seen that the elution time of Pb-EDTA, Cd-EDTA, Zn-EDTA, Cu-EDTA and EDTA in the solution containing EDTA and its complexed metal ions in the embodiment of the present invention is the same as that of a single standard metal complex, and has good reproducibility. At the same time, by comparing the experimental data of Example 2 to Example 7, it is found that the addition amount of sodium sulfide at different concentrations (0.1M, 0.2M, 0.4M, 0.8M, 1.6M and 2.0M) has different degrees of influence on the appearance of the chromatographic peaks of Pb-EDTA, Cd-EDTA, Zn-EDTA and Cu-EDTA in the solution containing EDTA and its complexed metal ions.

[0071] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting a solution containing EDTA and its complexed metal ions, characterized in that: include: Adding a precipitant to a solution containing EDTA and its complexed metal ions, mixing, centrifuging, and taking a supernatant; After the supernatant is filtered and diluted, it is tested by ion chromatography to obtain an ion chromatogram containing EDTA peaks and peaks of various metal EDTA complexes.

2. The method for detecting a solution containing EDTA and its complexed metal ions according to claim 1, characterized in that: The solution containing EDTA and its complexed metal ions is derived from the elution liquid used to elute heavy metal-contaminated soil using EDTA.

3. The method for detecting a solution containing EDTA and its complexed metal ions according to claim 1, characterized in that: The precipitant is one of Na2S, NaHS, CaS and FeS.

4. The method for detecting a solution containing EDTA and its complexed metal ions according to claim 1, characterized in that: The mobile phase used in the ion chromatograph detection is one of potassium hydroxide solution, sodium hydroxide solution, potassium bicarbonate solution, sodium bicarbonate solution, potassium carbonate solution and sodium carbonate solution.

5. A method for detecting a solution containing EDTA and its complexed metal ions according to any one of claims 1 to 4, characterized in that: The mobile phase used in the ion chromatograph detection is a potassium hydroxide solution, the concentration of the potassium hydroxide solution is 5 to 45 mM, and the retention time is 0.5 to 2.5 min.

6. The method for detecting a solution containing EDTA and its complexed metal ions according to claim 5, characterized in that: The mobile phase used in the ion chromatograph detection is potassium hydroxide solution, and when the concentration of the potassium hydroxide solution is 5 mM, the gradient of the mobile phase is controlled to have an end concentration of 15 mM and a retention time of 0.5 min.

7. The method for detecting a solution containing EDTA and its complexed metal ions according to claim 5, characterized in that: The mobile phase used in the ion chromatograph detection is potassium hydroxide solution, and when the concentration of the potassium hydroxide solution is 15 mM, the gradient of the mobile phase is controlled to have an end concentration of 30 mM and a retention time of 2.5 min.

8. The method for detecting a solution containing EDTA and its complexed metal ions according to claim 5, characterized in that: The mobile phase used in the ion chromatograph detection is potassium hydroxide solution, and when the concentration of the potassium hydroxide solution is 30 mM, the gradient of the mobile phase is controlled to have an end concentration of 45 mM and a retention time of 2.5 min.

9. The method for detecting a solution containing EDTA and its complexed metal ions according to claim 5, characterized in that: The mobile phase used in the ion chromatograph detection is potassium hydroxide solution, and when the concentration of the potassium hydroxide solution is 45 mM, the gradient of the mobile phase is controlled to have an end concentration of 5 mM and a retention time of 0.2 min.

10. A method for detecting a solution containing EDTA and its complexed metal ions according to any one of claims 6 to 9, characterized in that: When performing ion chromatography detection, the sample injection speed is 1.0 to 1.5 mL / min.

Images