A method for detecting sulfate ions

Abstract

The present invention relates to the technical field of ion detection, and particularly to a method for detecting sulfate ions. The detection method provided by the present invention includes the following steps: electrolyzing an aqueous solution of mirabilite; the electrolysis is carried out using an H-type electrolytic cell, the solution in the anode cell is sulfuric acid solution, and the solution in the cathode cell is sodium hydroxide solution; the middle cell is the aqueous solution of mirabilite; mixing the solution obtained in the anode cell after electrolysis with barium chloride solution, after a precipitation reaction occurs, mixing with a surfactant solution to obtain a suspension; measuring the turbidity of the suspension, substituting the turbidity of the suspension into a standard curve to obtain the concentration of sulfate ions; the abscissa of the standard curve is turbidity, and the ordinate is the concentration of sulfate ions. The detection method is simple and fast.

Description

Technical Field

[0001] The present invention relates to the technical field of ion detection, and in particular to a method for detecting sulfate ions. Background Art

[0002] In recent years, due to the rapid development of my country's nonferrous metal industry and coal industry, the emission of SO2 has increased day by day. Nonferrous metals mostly exist in the form of sulfides. Therefore, there will be a considerable amount of SO2 emissions in the pyrometallurgical process. Especially in the smelting process of nonferrous metals such as copper, nickel, lead and zinc, the emission of SO2 is as high as 7% to 28%. Due to the current uneven distribution of fuel, a considerable part of my country's regions still use coal for cooking and heating. In addition, the vast majority of smelters adopt pyrometallurgical smelting, which has a large demand for coal, thus aggravating the emission of SO2. At present, the desulfurization method for SO2 flue gas mostly adopts wet desulfurization. The desulfurizer used in wet desulfurization is sodium hydroxide solution. Because it has the advantages of large absorption capacity, low cost and few by-products, it has been widely used. However, the absorption product Na2SO4 (saltwater) / Na2SO3 waste liquid treatment is a problem to be solved.

[0003] The Chinese patent application number CN202110452881.0 discloses "a coupled process for flue gas desulfurization and resource utilization of sulfur-containing waste liquid". This process combines wet desulfurization and electrodialysis thenardite, which not only solves the problem of flue gas desulfurization but also solves the problem of resource utilization of thenardite. By converting thenardite into a mixed solution of sulfuric acid and a mixed solution of sodium hydroxide through electrolysis, the situation where the waste liquid is difficult to treat is solved. As for the detection of the sulfate ion concentration in the generated mixed solution, the conventional method is to directly use precision instruments to detect its concentration, but the commonly used precision instruments mentioned above have no way to detect high-concentration sulfate ions, and they need to be further diluted, and the above dilution process will produce large errors. Summary of the Invention

[0004] The present invention aims to provide a method for detecting sulfate ions, which is simple, convenient and quick.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for detecting sulfate ions, comprising the following steps:

[0007] The sodium sulfate aqueous solution is electrolyzed; the electrolysis adopts an H-type electrolytic cell, the solution of the anode cell is a sulfuric acid solution, the solution of the cathode cell is a sodium hydroxide solution; the middle cell is the sodium sulfate aqueous solution;

[0008] boiling the anode tank solution obtained after the electrolysis to concentrate it and obtain a concentrated solution;

[0009] Mix the concentrated solution with barium chloride solution. After a precipitation reaction occurs, mix it with a surfactant solution to obtain a suspension.

[0010] Measure the turbidity of the suspension, and substitute the turbidity of the suspension into the standard curve to obtain the concentration of sulfate ions in the suspension; the abscissa of the standard curve is the turbidity, and the ordinate is the concentration of sulfate ions.

[0011] Calculate the concentration of sulfate in the sodium sulfate aqueous solution according to the concentration of sulfate ions in the suspension.

[0012] The calculation formula is: C3 = (C1 * V1) / V2 - C2; where C1 is the concentration of sulfate ions in the suspension, V1 is the volume of the concentrated solution, C2 is the concentration of sulfate ions in the solution of the anode tank, and V2 is the volume of the anode tank solution obtained after electrolysis.

[0013] Preferably, the concentration of the sulfuric acid solution is 0.2 - 0.4 g / L.

[0014] The concentration of the sodium hydroxide solution is 0.5 - 0.7 g / L.

[0015] Preferably, the voltage of the electrolysis is 50 V and the time is 7 h.

[0016] Preferably, the volume ratio of the anode tank solution to the barium chloride solution is 1:1.

[0017] The concentration of the barium chloride solution is 100 g / L.

[0018] Preferably, the concentration of the surfactant solution is 10 g / L.

[0019] The volume ratio of the anode tank solution to the surfactant solution is 10:1.

[0020] Preferably, the surfactant in the surfactant solution is one or more of sodium lauryl sulfosuccinate monoester, sodium coconut monoethanolamide sulfosuccinate monoester, potassium monolauryl phosphate, and alcohol ether phosphate.

[0021] Preferably, the method for establishing the standard curve includes the following steps:

[0022] Mix a series of concentrations of sulfuric acid solution and barium chloride solution. After a precipitation reaction occurs, mix it with a surfactant solution to obtain a suspension.

[0023] Measure the turbidity of the suspension, and establish a standard curve with the concentration of the sulfuric acid solution as the ordinate and the turbidity of the suspension as the abscissa.

[0024] Preferably, the concentration of the sulfuric acid solution is 0 to 73.6 g / L.

[0025] Preferably, the concentration is achieved by boiling the anode cell solution obtained after electrolysis until the solution volume is reduced by one-fifth.

[0026] Preferably, the sodium sulfate in the aqueous sodium sulfate solution is obtained by wet flue gas desulfurization.

[0027] The present invention provides a method for detecting sulfate ions, comprising the following steps: electrolyzing an aqueous sodium sulfate solution; the electrolysis uses an H-type electrolytic cell, the solution in the anode cell is a sulfuric acid solution, and the solution in the cathode cell is a sodium hydroxide solution; the middle cell is the aqueous sodium sulfate solution; boiling the anode cell solution obtained after electrolysis for concentration to obtain a concentrated solution; mixing the concentrated solution with a barium chloride solution, after a precipitation reaction, mixing with a surfactant solution to obtain a suspension; measuring the turbidity of the suspension, substituting the turbidity of the suspension into a standard curve to obtain the concentration of sulfate ions in the suspension; the abscissa of the standard curve is turbidity, and the ordinate is the concentration of sulfate ions; calculating the concentration of sulfate in the aqueous sodium sulfate solution according to the concentration of sulfate ions in the suspension; the calculation formula is: C3 = (C1 * V1) / V2 - C2; where C1 is the concentration of sulfate ions in the suspension, V1 is the volume of the concentrated solution, C2 is the concentration of sulfate ions in the anode cell solution, and V2 is the volume of the anode cell solution obtained after electrolysis. Since during electrolysis, sulfate ions in the aqueous sodium sulfate solution will pass through the anion exchange membrane in the H-type electrolytic cell to the anode cell and combine with hydrogen ions generated at the anode to form sulfuric acid; sodium ions pass through the cation exchange membrane in the H-type electrolytic cell to the cathode cell and combine with hydroxide ions generated at the cathode to form sodium hydroxide. Therefore, directly mixing the anode cell solution obtained after electrolysis with a barium chloride solution, undergoing a precipitation reaction, and testing for sulfate ions can achieve the detection purpose; at the same time, adding a surfactant can make the generated barium sulfate precipitate uniformly and stably suspended in the solution system, making the turbidity measured subsequently accurate, thereby improving the accuracy of the detection. At the same time, the detection method is simple and convenient to operate. Description of the Drawings

[0028] Figure 1 The standard curve established for Example 1; <00000�3]]

[0029] Figure 2 The schematic flow chart of the detection process described in Examples 1 to 3. Detailed Embodiments

[0030] The present invention provides a method for detecting sulfate ions, comprising the following steps:

[0031] Electrolyze the aqueous sodium sulfate solution; the electrolysis uses an H-shaped electrolytic cell, the solution in the anode cell is sulfuric acid solution, and the solution in the cathode cell is sodium hydroxide solution; the middle cell is the aqueous sodium sulfate solution;

[0032] Boil and concentrate the anode cell solution obtained after the electrolysis to obtain a concentrated solution;

[0033] Mix the concentrated solution with barium chloride solution, after a precipitation reaction, mix it with a surfactant solution to obtain a suspension;

[0034] Measure the turbidity of the suspension, substitute the turbidity of the suspension into the standard curve to obtain the concentration of sulfate ions in the suspension; the abscissa of the standard curve is turbidity, and the ordinate is the concentration of sulfate ions;

[0035] Calculate the concentration of sulfate in the aqueous sodium sulfate solution according to the concentration of sulfate ions in the suspension;

[0036] The calculation formula is: C3 = (C1 * V1) / V2 - C2, where C1 is the concentration of sulfate ions in the suspension, V1 is the volume of the concentrated solution, C2 is the concentration of sulfate ions in the anode cell solution, and V2 is the volume of the anode cell solution obtained after the electrolysis.

[0037] In the present invention, unless otherwise specified, all raw materials are commercially available products well-known to those skilled in the art.

[0038] In the present invention, the method for establishing the standard curve preferably includes the following steps:

[0039] Mix a series of concentrations of sulfuric acid solution and barium chloride solution, after a precipitation reaction, mix it with a surfactant solution to obtain a suspension;

[0040] Measure the turbidity of the suspension, and establish a standard curve with the concentration of the sulfuric acid solution as the ordinate and the turbidity of the suspension as the abscissa.

[0041] In the present invention, a series of concentrations of sulfuric acid solution and barium chloride solution are mixed, after a precipitation reaction, mixed with a surfactant solution to obtain a suspension.

[0042] In the present invention, the concentration of the series of concentrations of sulfuric acid solution is preferably 0.0 - 73.6 g / L.

[0043] In a specific embodiment of the present invention, the concentrations of the series of sulfuric acid solutions are successively 0, 3.68 g / L, 7.36 g / L, 14.72 g / L, 29.44 g / L, 36.8 g / L, and 73.6 g / L. The series of sulfuric acid solutions are preferably prepared. The preparation process is preferably to transfer 0 mL, 0.1 mL, 0.2 mL, 0.6 mL, 0.8 mL, 1 mL, and 2 mL of concentrated sulfuric acid with a mass concentration of 1.84 g / mL into a 50 mL volumetric flask for volume fixation respectively, to obtain the above series of sulfuric acid solutions.

[0044] In the present invention, the concentration of the barium chloride solution is preferably 100 g / L.

[0045] In the present invention, the volume ratio of the sulfuric acid solution to the barium chloride solution is preferably 1:1.

[0046] In the present invention, the mixing of the sulfuric acid solution and the barium chloride solution is preferably to add the sulfuric acid solution into the colorimetric flasks containing the barium chloride solution respectively for shaking.

[0047] In the present invention, a precipitation reaction starts when the sulfuric acid solution and the barium chloride solution begin to be mixed.

[0048] In the present invention, the concentration of the surfactant solution is preferably 10 g / L; the volume ratio of the anode bath solution to the surfactant solution is preferably 10:1.

[0049] In the present invention, the surfactant in the surfactant solution is preferably one or more of sodium lauryl sulfosuccinate monoester, sodium cocoyl monoethanolamide sulfosuccinate monoester, potassium monolauryl phosphate, and alcohol ether phosphate; when there are two or more of the above specific substances as the surfactant, the present invention has no special limitation on the ratio of the above specific substances, and they can be mixed in any ratio.

[0050] In the present invention, the turbidity of the suspension is preferably measured by a turbidimeter; the present invention has no special limitation on the measurement process, and it can be carried out by using a process well-known to those skilled in the art.

[0051] In the present invention, the aqueous sodium sulfate solution is electrolyzed; the electrolysis uses an H-shaped electrolytic cell, the solution in the anode bath is a sulfuric acid solution, the solution in the cathode bath is a sodium hydroxide solution; the middle bath is the aqueous sodium sulfate solution.

[0052] In the present invention, the sodium sulfate in the aqueous sodium sulfate solution is obtained by wet flue gas desulfurization, that is, the sulfur-containing flue gas reacts with the NaOH solution in the spray tower to generate a mixed solution of sodium sulfate and sodium sulfite, and then it is dried to obtain a solid waste; the solid waste is the sodium sulfate in the aqueous sodium sulfate solution.

[0053] In the present invention, the sodium sulfate aqueous solution is preferably obtained by mixing 10 g of sodium sulfate and 300 mL of deionized water.

[0054] In the present invention, the concentration of the sulfuric acid solution is 0.31 g / L; the concentration of the sodium hydroxide solution is 0.67 g / L.

[0055] In the present invention, the voltage of the electrolysis is preferably 50 V, and the time is preferably 7 h.

[0056] After the electrolysis is completed, in the present invention, the anode cell solution obtained after the electrolysis is mixed with a barium chloride solution. After a precipitation reaction occurs, it is mixed with a surfactant solution to obtain a suspension; the turbidity of the suspension is measured, and the turbidity of the suspension is substituted into a standard curve to obtain the concentration of sulfate ions; the abscissa of the standard curve is the turbidity, and the ordinate is the concentration of sulfate ions.

[0057] After the electrolysis is completed, the present invention also preferably includes boiling the anode cell solution until the volume of the solution is reduced by one-fifth. In the present invention, the purpose of the boiling is to remove the interfering carbonate ions and carbon dioxide dissolved in the aqueous solution.

[0058] The process of obtaining the suspension and measuring the turbidity preferably refers to the process corresponding to the establishment of the standard curve above, and will not be elaborated here.

[0059] The following is a detailed description of the method for detecting sulfate ions in an electrolyzed sodium sulfate system provided by the present invention in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0060] Example 1

[0061] 0 mL, 0.1 mL, 0.2 mL, 0.6 mL, 0.8 mL, 1 mL and 2 mL of concentrated sulfuric acid with a mass concentration of 1.84 g / mL are respectively transferred to a 50 mL volumetric flask for volume fixing to obtain a series of sulfuric acid solutions with the above concentrations;

[0062] 10 g of barium chloride is placed in a 100 mL volumetric flask for volume fixing to obtain a barium chloride solution;

[0063] 10 mL of the barium chloride solution is respectively placed in the colorimetric flasks of 7 turbidimeters, and then 10 mL of the above series of sulfuric acid solutions are respectively added. After sufficient shaking, 1 mL of a sodium lauryl sulfosuccinate solution with a concentration of 20 g / L is added. After sufficient shaking to form a suspension, it is placed in a turbidimeter for testing, and the data is recorded and a standard curve is established (as Figure 1 shown);

[0064] The sulfur-containing flue gas reacts with a NaOH solution in a spray tower to generate a mixed solution of thenardite and sodium sulfite, which is then dried to obtain solid waste (the thenardite);

[0065] 10g of the solid waste was mixed with 300mL of deionized water to obtain a sodium sulfate aqueous solution, which was placed in the middle tank of an H-type electrolytic cell. A sulfuric acid solution with a concentration of 0.31g / L was added to the anode tank, and a sodium hydroxide solution with a concentration of 0.67g / L was added to the cathode tank for electrolysis. The voltage of the electrolysis was 50V, and the time was 60min. 50mL of the solution in the anode tank was boiled until the volume of the solution was reduced by one-fifth. After cooling, 10mL was placed in a colorimetric bottle containing 10mL of the barium chloride solution and fully shaken. 1mL of a 20g / L disodium lauryl sulfosuccinate solution was added, and the solution was shaken and the turbidity was tested. The turbidity was brought into Figure 1 In the standard curve shown, the test result is 1.5 g / L;

[0066] The concentration of sulfate in the sodium sulfate aqueous solution was calculated to be 0.89 g / L based on the concentration of sulfate ions in the anode tank solution.

[0067] Example 2

[0068] The sulfur-containing flue gas reacts with a NaOH solution in a spray tower to generate a mixed solution of thenardite and sodium sulfite, which is then dried to obtain solid waste (the thenardite);

[0069] 10g of the solid waste was mixed with 300mL of deionized water to obtain a sodium sulfate aqueous solution, which was placed in the middle tank of an H-type electrolytic cell. A sulfuric acid solution with a concentration of 0.31g / L was added to the anode tank, and a sodium hydroxide solution with a concentration of 0.67g / L was added to the cathode tank for electrolysis. The voltage of the electrolysis was 50V, and the time was 240min. 50mL of the solution in the anode tank was boiled until the volume of the solution was reduced by one-fifth. After cooling, 10mL was placed in a colorimetric bottle containing 10mL of the barium chloride solution and fully shaken. 1mL of a 20g / L disodium lauryl sulfosuccinate solution was added, and the solution was shaken and the turbidity was tested. The turbidity was brought into Figure 1 In the standard curve shown, the test result is 12 g / L;

[0070] The concentration of sulfate in the sodium sulfate aqueous solution was calculated based on the concentration of sulfate ions in the anode tank solution to be 9.29 g / L.

[0071] Example 3

[0072] The sulfur-containing flue gas reacts with a NaOH solution in a spray tower to generate a mixed solution of thenardite and sodium sulfite, which is then dried to obtain solid waste (the thenardite);

[0073] Mix 10 g of the solid waste with 300 mL of deionized water to obtain a sodium sulfate aqueous solution, and place it in the middle tank of an H-type electrolytic cell. Add a sulfuric acid solution with a concentration of 0.31 g / L to the anodic tank and a sodium hydroxide solution with a concentration of 0.67 g / L to the cathodic tank, and perform electrolysis. The voltage of the electrolysis is 50 V and the time is 420 min. Then, take 50 mL of the solution from the anodic tank and boil it until the volume of the solution decreases by one-fifth. After cooling, take 10 mL and place it in a colorimetric flask containing 10 mL of the barium chloride solution, shake it well, add 1 mL of a sodium lauryl sulfosuccinate solution with a concentration of 20 g / L, shake it evenly, measure its turbidity, and substitute the turbidity into Figure 1 the standard curve shown in

[0074] Calculate the concentration of sulfate ions in the sodium sulfate aqueous solution as 31.69 g / L according to the concentration of sulfate ions in the solution of the anodic tank.

[0075] Comparative Example 1

[0076] Test the sodium sulfate aqueous solutions in Examples 1 to 3 according to the standard of HJ / T 342-2007 (barium chromate spectrophotometry method), and the test results are 0.85 g / L, 9.24 g / L, and 32.12 g / L respectively.

[0077] Perform a statistical analysis on the test results of Examples 1 to 3 and Comparative Example 1, as shown in Table 1:

[0078] Table 1 Statistical analysis of the test results of Examples 1 to 3 and Comparative Example 1

[0079]

[0080]

[0081] Among them, Statistic 1 and Statistic 2 are the comparison results of the turbidimeter method with the barium sulfate turbidimetry method and the turbidimeter method with the barium chromate spectrophotometry method respectively, F is the ratio of Statistic 1 to Statistic 2, and F

[0083] ,

[0079] ,

[0082] ,

[0078] ,

[0081] ,

[0077] , ,

[0076] , , , , , 0.05 , , , , , ,

[0080] [[ID=​​​​​​

Claims

1. A method for detecting sulfate ions, characterized in that: The following steps are involved: The sodium sulfate aqueous solution is electrolyzed; the electrolysis adopts an H-type electrolytic cell, the solution of the anode tank is a sulfuric acid solution, and the solution of the cathode tank is a sodium hydroxide solution; The middle tank is the said Glauber's salt aqueous solution; boiling the anode tank solution obtained after the electrolysis to concentrate it and obtain a concentrated solution; The concentrated solution is mixed with a barium chloride solution to produce a precipitation reaction, and then mixed with a surfactant solution to obtain a suspension; Testing the turbidity of the suspension, substituting the turbidity of the suspension into a standard curve to obtain the concentration of sulfate ions in the suspension; the abscissa of the standard curve is turbidity, and the ordinate is the concentration of sulfate ions; Calculating the concentration of sulfate in the sodium sulfate aqueous solution according to the concentration of sulfate ions in the suspension; The calculation formula is: C3 = (C1*V1) / V2-C2; wherein C1 is the concentration of sulfate ions in the suspension, V1 is the volume of the concentrated solution, C2 is the concentration of sulfate ions in the solution of the anode tank, and V2 is the volume of the anode tank solution obtained after the electrolysis; The sodium sulfate in the sodium sulfate aqueous solution is obtained by wet desulfurization, that is, sulfur-containing flue gas reacts with a NaOH solution in a spray tower to generate a mixed solution of sodium sulfate and sodium sulfite, which is then dried to obtain solid waste; the solid waste is the sodium sulfate in the sodium sulfate aqueous solution; The surfactant in the surfactant solution is disodium lauryl sulfosuccinate; The voltage of the electrolysis was 50 V and the time was 7 h.

2. The detection method according to claim 1, wherein The concentration of the sulfuric acid solution is 0.2-0.4 g / L; The concentration of the sodium hydroxide solution is 0.5-0.7 g / L.

3. The detection method according to claim 1, wherein The volume ratio of the anode tank solution to the barium chloride solution is 1:1; The concentration of the barium chloride solution is 100 g / L.

4. The detection method according to claim 1, wherein The concentration of the surfactant solution is 10 g / L; The volume ratio of the anode tank solution to the surfactant solution is 10:

1.

5. The detection method according to any one of claims 1 to 4, characterized in that The method for establishing the standard curve comprises the following steps: A series of sulfuric acid solutions and barium chloride solutions are mixed to produce a precipitation reaction, and then mixed with a surfactant solution to obtain a suspension; The turbidity of the suspension was tested, and a standard curve was established with the concentration of the sulfuric acid solution as the ordinate and the turbidity of the suspension as the abscissa.

6. The detection method according to claim 5, wherein The concentration of the sulfuric acid solution is 0-73.6 g / L.

7. The detection method according to claim 1, wherein The concentration is to boil the anode tank solution obtained after the electrolysis until the volume of the solution is reduced by one fifth.

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