Method for rapidly determining content of sulfate radicals in grey water dispersing agent
By combining dilution and titration methods with formula calculations, the accuracy problem in determining sulfate content in ash water dispersants was solved, realizing a rapid, simple, and environmentally friendly determination method.
Patent Information
- Application Number
- CN202511638149.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-10
- Publication Date
- 2026-01-27
AI Technical Summary
Existing methods cannot accurately determine the sulfate content in ash water dispersants, and are complex to operate and have poor environmental friendliness.
The sample was diluted and mixed with hydrochloric acid, barium chloride, disodium magnesium ethylenediaminetetraacetate, and Eriochrome Black T indicator. The mixture was then titrated with EDTA standard titration solution until a color change was observed. The sulfate content was then calculated using a formula.
It enables rapid and accurate determination of sulfate content in ash water dispersants without the need for digestion pretreatment, simplifying operation and reducing environmental pollution.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of coal gasification water treatment technology, specifically to a method for rapidly determining the sulfate content in ash water dispersants. Background Technology
[0002] In the coal gasification process water system, after the molten slag and crude syngas in the gasifier are cooled and washed, a black water body with high solid content is produced. This water body is defined as gasification black water. After flocculation and sedimentation treatment, the supernatant becomes clear, with only a small amount of fine ash remaining. This supernatant is gasification ash water. The clarified ash water in the sedimentation tank overflows into the circulating water tank. A dispersant needs to be added to the tank to achieve stable dispersion of solid particles in the ash water, thereby preventing their deposition and scaling. Therefore, the dispersant is an indispensable key agent in the coal gasification water treatment process.
[0003] Currently, commercially available dispersants are mainly divided into four categories: inorganic, organic, polymeric, and composite. The appropriate type should be selected based on specific water quality conditions. However, some manufacturers add inorganic acids such as sulfuric acid to their dispersants to reduce costs. Excessive sulfuric acid can have multiple negative impacts on the water and system: firstly, it directly exacerbates pipe corrosion by reducing water resistance to increase electrochemical corrosion, and indirectly interferes with the cycle of sulfate-reducing bacteria, accelerating the spread of biological corrosion; secondly, excessive sulfate can cause foul odors in the water, damaging the aquatic environment.
[0004] Currently, there are no clearly reported methods in the literature for determining the sulfate content in dispersants. Although there are established methods for determining sulfate content in water samples (such as gravimetric methods, spectrophotometric methods, volumetric methods, and ion chromatography), the active ingredients of dispersants are mainly organic carboxylic acids. These dispersants not only contain a large amount of organic matter and have high acidity, but the reagents themselves are often yellow or brownish-red. Due to these matrix characteristics, existing conventional methods have limitations and cannot accurately determine the actual sulfate content in these types of reagents. Therefore, there is an urgent need to develop a method for rapidly determining the sulfate content in ash water dispersants. Summary of the Invention
[0005] The purpose of this invention is to overcome the problems of existing methods for determining sulfate content being complex, environmentally unfriendly, and inaccurate in determining sulfate content in ash water dispersants. This invention provides a rapid method for determining sulfate content in ash water dispersants. This method not only fills a gap in related testing methods but also eliminates the need for pre-treatment of the test sample before digestion. It features simple operation, short testing time, small error, wide measurement range, and ease of implementation. The results are accurate and environmentally friendly, showing broad application prospects in the field of coal gasification water treatment.
[0006] To achieve the above objectives, the present invention provides a method for rapidly determining the sulfate content in an ash water dispersant, the method comprising the following steps:
[0007] (1) Dilute the sample to be tested, then mix the partially diluted sample solution with hydrochloric acid solution, then mix the resulting reaction product with barium chloride solution, then mix the resulting reaction product with disodium magnesium ethylenediaminetetraacetate solution, then mix the resulting reaction product with ammonia-ammonium chloride buffer solution and chrome black T indicator, and finally titrate with EDTA standard titration solution until the solution color changes from wine red to bright blue, and record the volume V1 of the EDTA standard titration solution consumed;
[0008] (2) Take an equal volume of water to the partially diluted sample solution described in step (1) and mix it with an equal volume of barium chloride solution and disodium magnesium ethylenediaminetetraacetate solution from step (1). Then, mix the resulting reaction product with an equal volume of ammonia-ammonium chloride buffer solution and chrome black T indicator from step (1). Then, titrate with EDTA standard titration solution until the solution color changes from wine red to bright blue. Record the volume V2 of the EDTA standard titration solution consumed.
[0009] (3) Take another part of the diluted sample solution of the test, which is equal in volume to that of the partially diluted sample solution in step (1), and mix it with hydrochloric acid solution. Then, mix the resulting reaction product with an equal volume of ammonia-ammonium chloride buffer solution and chrome black T indicator from step (1), and then titrate it with EDTA standard titration solution until the solution color changes from wine red to bright blue. Record the volume V3 of the EDTA standard titration solution consumed.
[0010] (4) Calculate the sulfate content in the sample to be tested using the following formula, expressed as a mass fraction ρ;
[0011]
[0012] Wherein, V1 is the volume of the EDTA standard titration solution consumed in step (1), in mL;
[0013] V2 is the volume of the EDTA standard titration solution consumed in step (2), in mL;
[0014] V3 is the volume of the EDTA standard titration solution consumed in step (3), in mL;
[0015] C represents the concentration of the EDTA standard titration solution, in mol / L;
[0016] m is the mass of the test sample in the partially diluted test sample solution, in grams.
[0017] Preferably, in step (1), the total amount of sulfate in the partially diluted sample solution is less than 50 mg.
[0018] Preferably, in step (1), the total amount of sulfate in the partially diluted sample solution is less than 30 mg.
[0019] Preferably, in step (1), the volume ratio of the partially diluted sample solution to the hydrochloric acid solution is 100:0.5-5.
[0020] Preferably, the concentration of the hydrochloric acid solution is 1-5 mol / L.
[0021] Preferably, in step (1), the volume ratio of the partially diluted sample solution to the barium chloride solution is 100:10-50.
[0022] Preferably, the concentration of the barium chloride solution is 0.01-0.05 mol / L.
[0023] Preferably, in step (1), the volume ratio of the barium chloride solution to the disodium magnesium ethylenediaminetetraacetate solution is 1:0.5-1.5.
[0024] Preferably, the concentration of the disodium magnesium ethylenediaminetetraacetate solution is 0.01-0.05 mol / L.
[0025] Preferably, in step (1), the volume ratio of the partially diluted test sample solution to the ammonia-ammonium chloride buffer solution is 100:10-20.
[0026] Preferably, the pH value of the ammonia-ammonium chloride buffer solution is 7-10.
[0027] Preferably, the ammonia-ammonium chloride buffer solution comprises ammonium chloride, ammonia water, and water.
[0028] Preferably, the amount of the Chrome Black T indicator is 2-7 drops.
[0029] Preferably, the Chrome Black T indicator comprises Chrome Black T, hydroxylamine hydrochloride and ethanol, and the concentration of Chrome Black T in the Chrome Black T indicator is 1-5 g / L.
[0030] The method described in this invention involves diluting an ash-water dispersant to the desired concentration. First, the diluted sample solution is mixed with hydrochloric acid solution to eliminate interference from carbonate and phosphate ions. Then, it is mixed with excess barium chloride solution to completely convert sulfate ions in the sample into insoluble barium sulfate precipitate. Next, disodium magnesium ethylenediaminetetraacetate solution is added. Through the displacement of magnesium by excess barium ions, the endpoint color change in the Eriochrome Black T indicator system is enhanced, improving the sensitivity of endpoint determination. Furthermore, this method further analyzes the total calcium and magnesium content of the dispersant, eliminating interference from calcium and magnesium ions and ensuring the accuracy of the test results. Compared to conventional titration, gravimetric methods, ion chromatography, and ICP methods, the method described in this invention does not require pretreatment of the test sample before digestion, nor does it require filtration, washing, or drying of the precipitate. It can determine the sulfate content in the dispersant in a shorter time. Moreover, this method is simple to operate, has a wide range of applications, small analytical errors, and avoids the use of large amounts of alcohol and ketone solvents, making it highly environmentally friendly and promising for application in the field of coal gasification water treatment. Detailed Implementation
[0031] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.
[0032] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0033] The method for rapid determination of sulfate content in ash water dispersant according to the present invention includes the following steps:
[0034] (1) Dilute the sample to be tested, then mix the partially diluted sample solution with hydrochloric acid solution, then mix the resulting reaction product with barium chloride solution, then mix the resulting reaction product with disodium magnesium ethylenediaminetetraacetate solution, then mix the resulting reaction product with ammonia-ammonium chloride buffer solution and chrome black T indicator, and finally titrate with EDTA standard titration solution until the solution color changes from wine red to bright blue, and record the volume V1 of the EDTA standard titration solution consumed;
[0035] (2) Take an equal volume of water to the partially diluted sample solution described in step (1) and mix it with an equal volume of barium chloride solution and disodium magnesium ethylenediaminetetraacetate solution from step (1). Then, mix the resulting reaction product with an equal volume of ammonia-ammonium chloride buffer solution and chrome black T indicator from step (1). Then, titrate with EDTA standard titration solution until the solution color changes from wine red to bright blue. Record the volume V2 of the EDTA standard titration solution consumed.
[0036] (3) Take another part of the diluted sample solution of the test, which is equal in volume to that of the partially diluted sample solution in step (1), and mix it with hydrochloric acid solution. Then, mix the resulting reaction product with an equal volume of ammonia-ammonium chloride buffer solution and chrome black T indicator from step (1), and then titrate it with EDTA standard titration solution until the solution color changes from wine red to bright blue. Record the volume V3 of the EDTA standard titration solution consumed.
[0037] (4) Calculate the sulfate content in the sample to be tested using the following formula, expressed as a mass fraction ρ;
[0038]
[0039] Wherein, V1 is the volume of the EDTA standard titration solution consumed in step (1), in mL;
[0040] V2 is the volume of the EDTA standard titration solution consumed in step (2), in mL;
[0041] V3 is the volume of the EDTA standard titration solution consumed in step (3), in mL;
[0042] C represents the concentration of the EDTA standard titration solution, in mol / L;
[0043] m is the mass of the test sample in the partially diluted test sample solution, in grams.
[0044] In the method described in this invention, since the sulfate concentration in some dispersant samples is too high, exceeding the applicable range for titration, it may lead to inaccurate test results. Therefore, it is necessary to dilute the sample to be tested. This invention does not limit the dilution factor of the sample to be tested, but it can be changed accordingly based on the different characteristics of the sample.
[0045] In some embodiments, in step (1), to ensure the accuracy of the test results, it is necessary to limit the sulfate content in the partially diluted test sample solution. Specifically, the total amount of sulfate in the partially diluted test sample solution is less than 50 mg. Preferably, the total amount of sulfate in the partially diluted test sample solution is less than 30 mg. More preferably, the total amount of sulfate in the partially diluted test sample solution is less than 20 mg.
[0046] In the method described in this invention, in step (1), the partially diluted sample solution to be tested is mixed with the hydrochloric acid solution and reacted to convert carbonate ions that may exist in the test sample into carbon dioxide and water, and phosphate ions into poorly ionized phosphoric acid, thereby eliminating the interference of carbonate ions and phosphate ions in the dispersant and ensuring the accuracy of the test results.
[0047] In some embodiments, in step (1), to ensure sufficient elimination of interference from carbonate and phosphate ions in the dispersant, the concentration of the hydrochloric acid solution used needs to be limited. Specifically, the concentration of the hydrochloric acid solution is preferably 1-5 mol / L, more preferably 1.25-4 mol / L, and even more preferably 1.5-3 mol / L.
[0048] In some embodiments, in step (1), to ensure sufficient elimination of interference from carbonate and phosphate ions in the sample to be tested, the volume ratio of the partially diluted sample solution to the hydrochloric acid solution needs to be limited. Specifically, the volume ratio of the partially diluted sample solution to the hydrochloric acid solution is preferably 100:0.5-5, more preferably 100:0.75-3, and even more preferably 100:1-2.5.
[0049] In the method described in this invention, in step (1), the addition of the barium chloride solution can convert sulfate ions in the sample to be tested into barium sulfate precipitate. In this invention, the concentration of the barium chloride solution is 0.01-0.05 mol / L, preferably 0.02-0.04 mol / L.
[0050] In some embodiments, in step (1), to ensure that all sulfate ions in the sample react with barium ions to form barium sulfate precipitate, the volume ratio of the partially diluted sample solution to the barium chloride solution needs to be limited. Specifically, the volume ratio of the partially diluted sample solution to the barium chloride solution is preferably 100:10-50, more preferably 100:15-40, and even more preferably 100:20-30. As a specific example, the volume ratio of the partially diluted sample solution to the barium chloride solution can be 100:20, 100:22, 100:24, 100:26, 100:28, or 100:30.
[0051] In the method described in this invention, due to the weak complexation ability of barium ions with Eriochrome Black T indicator, direct titration leads to a blurred endpoint color change (the transition from red to blue is not obvious), thus affecting the accuracy of the measurement results. Because the complexation constant of EDTA with barium ions is greater than that with magnesium ions, a "complexation displacement" reaction occurs in the system after adding a solution of disodium magnesium ethylenediaminetetraacetate (EDTA-Mg): EDTA preferentially complexes with free barium ions, simultaneously releasing magnesium ions from EDTA-Mg; after the barium ions are completely titrated, excess EDTA further complexes with the released magnesium ions, and removes the red complex previously formed by the magnesium ions and Eriochrome Black T indicator, ultimately causing the solution to abruptly turn the indicator's blue color. This process, utilizing the stronger complexation ability of magnesium ions with the indicator, transforms the originally insensitive titration endpoint of barium ions into a clear color change endpoint of magnesium ions, thereby significantly improving titration accuracy.
[0052] In some embodiments, in step (1), the concentration of the disodium magnesium ethylenediaminetetraacetate solution is 0.01-0.05 mol / L, preferably 0.02-0.04 mol / L.
[0053] In some embodiments, in step (1), to further improve the titration accuracy, it is necessary to limit the volume ratio of the barium chloride solution to the disodium magnesium ethylenediaminetetraacetate solution. Specifically, the volume ratio of the barium chloride solution to the disodium magnesium ethylenediaminetetraacetate solution is preferably 1:0.5-1.5, more preferably 1:0.8-1.2, and even more preferably 1:0.9-1.1.
[0054] In the method described in this invention, in step (1), in order to ensure the smooth progress of the titration process, the pH value of the ammonia-ammonium chloride buffer solution needs to be limited. Specifically, the pH value of the ammonia-ammonium chloride buffer solution is preferably 7-10, and more preferably 7.5-9.5.
[0055] In this invention, the ammonia-ammonium chloride buffer solution comprises ammonium chloride, ammonia water, and water. During specific testing, the amounts of ammonium chloride, ammonia water, and water can be adjusted according to the desired pH of the ammonia-ammonium chloride buffer solution. This method is a standard operating procedure in the art and will not be elaborated further here.
[0056] In one embodiment, in step (1), to ensure the smooth progress of the titration process, it is necessary to limit the volume ratio of the partially diluted test sample solution to the ammonia-ammonium chloride buffer solution. Specifically, the volume ratio of the partially diluted test sample solution to the ammonia-ammonium chloride buffer solution is preferably 100:10-20, and more preferably 100:12-18.
[0057] In this invention, the Chrome Black T indicator comprises Chrome Black T, hydroxylamine hydrochloride, and ethanol. The concentration of Chrome Black T in the indicator can be 1-5 g / L, preferably 1.5-4 g / L, and more preferably 2-3 g / L. In specific testing procedures, the amounts of Chrome Black T, hydroxylamine hydrochloride, and ethanol in the Chrome Black T indicator can be adjusted according to the desired concentration of the Chrome Black T indicator. This method is a standard operating procedure in the art and will not be elaborated further here.
[0058] In one embodiment, in step (1), in order to ensure the smooth progress of the titration process, the amount of the Chrome Black T indicator needs to be limited. Specifically, the amount of the Chrome Black T indicator is preferably 2-7 drops, and more preferably 3-5 drops.
[0059] In the method described in this invention, in step (2), an equal volume of water is used to replace the partially diluted sample solution described in step (1) as a blank control group, so that EDTA complexes with the barium ions in the added barium chloride solution and the magnesium ions in the disodium magnesium ethylenediaminetetraacetate solution. Since the complexation coefficient between barium ions and EDTA is 1:1, the amount of barium ions in the added barium chloride solution is obtained by the volume V2 of EDTA standard solution consumed.
[0060] In the method described in this invention, the purpose of step (3) is mainly to determine the original calcium and magnesium ion content in the diluted sample solution, that is, the volume V3 of EDTA standard solution consumed by the calcium and magnesium ions in the ash water dispersant, and to eliminate the influence of the original calcium and magnesium ions in the diluted sample solution.
[0061] It should be noted that this invention does not impose any particular limitation on the reaction time; after the reagents are mixed and shaken well, they can be allowed to stand for 1-5 minutes. Furthermore, the preparation processes for all reagents used in this invention are common methods in the field and will not be elaborated upon further here.
[0062] It should be further noted that, in order to ensure the accuracy of the experimental results, the concentration and amount of the reagents used in steps (2) and (3) should be consistent with those in step (1).
[0063] The following examples further illustrate the method for rapidly determining the sulfate content in ash water dispersant according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.
[0064] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.
[0065] In the following examples and comparative examples, the reference value of sulfate mass fraction in dispersant No. 1 is 6.5%, which is referred to as the first test sample;
[0066] The reference value for the sulfate mass fraction in dispersant No. 2 is 0, and it is designated as the second sample to be tested.
[0067] The reference value for the sulfate mass fraction in dispersant No. 3 is 21%, and it is designated as the third sample to be tested.
[0068] Example 1
[0069] Preparation of reagents
[0070] 0.01 mol / L EDTA standard titration solution: Weigh 3.7300 g of working standard reagent disodium ethylenediaminetetraacetate, dissolve it in hot water, cool to room temperature, transfer to a 1000 mL volumetric flask, and dilute to the mark.
[0071] Transfer to a reagent bottle for later use;
[0072] 0.02 mol / L barium chloride solution: Weigh 2.4 g of barium chloride, dissolve it in 500 mL of water, let it stand at room temperature for 24 h, filter it and use it;
[0073] 0.02 mol / L magnesium disodium ethylenediaminetetraacetate solution: Accurately weigh 17.2000 g magnesium disodium ethylenediaminetetraacetate (C 10 H 12 Dissolve MgN2Na2O8·4H2O in water, dilute with water to a final volume of 1L in a volumetric flask, and store in a reagent bottle for later use.
[0074] Ammonia-ammonium chloride buffer solution (pH=9): Weigh 20g of ammonium chloride, dilute with water, add 100mL of 25% ammonia solution, and dilute with water to 1L;
[0075] 2 g / L Chrome Black T indicator: Weigh 0.2 g Chrome Black T and 2 g hydroxylamine hydrochloride, dissolve in 95% ethanol, dilute to 100 mL with 95% ethanol, and store in a brown bottle;
[0076] Test sulfate content
[0077] (1) Weigh 1g of the first test sample and dilute it with water so that the total amount of sulfate in the diluted first test sample solution is less than 20mg. First, put 50mL of the diluted first test sample solution into a 250mL conical flask, then add 0.5mL of 2mol / L hydrochloric acid solution, mix and shake well, and let stand for 2min. Then add 10mL of barium chloride solution, shake well and let stand for 5min. Then add 10mL of disodium magnesium ethylenediaminetetraacetate, mix and shake well and let stand for 2min. Then add 7mL of ammonia-ammonium chloride buffer solution and 3-5 drops of chrome black T indicator. Finally, titrate with 0.01mol / L EDTA standard solution until the solution color changes from wine red to bright blue. Record the volume V1 of the EDTA standard titration solution consumed.
[0078] (2) Take 50 mL of water and put it into a 250 mL Erlenmeyer flask. Then add 10 mL of barium chloride solution and 10 mL of magnesium disodium ethylenediaminetetraacetate. Mix and shake well, then let stand for 2 min. Then add 7 mL of ammonia-ammonium chloride buffer solution and 3-5 drops of chrome black T indicator. Finally, titrate with 0.01 mol / L EDTA standard solution until the solution color changes from wine red to bright blue. Record the volume V2 of the EDTA standard titration solution consumed.
[0079] (3) Take 50 mL of the diluted first test sample solution and place it in a 250 mL Erlenmeyer flask. Then add 0.5 mL of 2 mol / L hydrochloric acid solution, mix and shake well, and let stand for 2 min. Then add 7 mL of ammonia-ammonium chloride buffer solution and 3-5 drops of chrome black T indicator. Finally, titrate with 0.01 mol / L EDTA standard solution until the solution color changes from wine red to bright blue. Record the volume V3 of the EDTA standard titration solution consumed.
[0080] (4) Calculate the mass fraction ρ of sulfate in the sample using the following formula;
[0081]
[0082] Wherein, V1 is the volume of the EDTA standard titration solution consumed in step (1), in mL;
[0083] V2 is the volume of the EDTA standard titration solution consumed in step (2), in mL;
[0084] V3 is the volume of the EDTA standard titration solution consumed in step (3), in mL;
[0085] C represents the concentration of the EDTA standard titration solution, in mol / L;
[0086] m is the mass of the test sample in the partially diluted first test sample solution, in grams;
[0087] The test was repeated twice, and the results are shown in Table 1.
[0088] Example 2
[0089] The method described in Example 1 was implemented, except that the first test sample was replaced with the second test sample, and the test was repeated twice. The results are shown in Table 1.
[0090] Example 3
[0091] The method described in Example 1 was implemented, except that the first test sample was replaced with the third test sample, and the test was repeated twice. The results are shown in Table 1.
[0092] Example 4
[0093] The method described in Example 2 was implemented, except that 0.5% sulfate (the volume of sulfate added was negligible) was added to the second sample to be tested, and the test was repeated twice. The results are shown in Table 2.
[0094] Example 5
[0095] The method described in Example 2 was implemented, except that 5% sulfate (the volume of sulfate added was negligible) was added to the second sample to be tested, and the test was repeated twice. The results are shown in Table 2.
[0096] Example 6
[0097] The method described in Example 2 was implemented, except that 10% sulfate (the volume of sulfate added was negligible) was added to the second sample to be tested, and the test was repeated twice. The results are shown in Table 2.
[0098] Comparative Example 1
[0099] Using the sample from Example 4 as the research object, the sulfate content was tested by gravimetric method. The specific implementation process is as follows: A certain volume of the same sample as in Example 4 was taken into a 400mL beaker, 2-3 drops of methyl red were added, and the solution was adjusted to red with hydrochloric acid solution. The solution was heated to boiling, and a certain amount of hot barium chloride solution was added while stirring continuously. The mixture was stirred vigorously for 2 minutes, cooled to room temperature, and a small amount of barium chloride solution was added to check whether the precipitation was complete. The mixture was filtered using a glass crucible that had been dried and weighed beforehand at 120℃. The supernatant was first poured into the crucible and washed with water until no chloride ions were present (tested with silver nitrate solution; no white turbidity was produced in the washings). The outer wall of the crucible was rinsed with a small amount of water and then placed in a constant temperature drying oven at 120℃±2℃ for 1 hour. The crucible was then removed, weighed, and dried again until constant weight was achieved. The test was repeated twice, and the results are shown in Table 2.
[0100] Comparative Example 2
[0101] The method described in Comparative Example 1 was carried out, except that the sample used in Example 5 was used instead of the sample used in Example 4; the test was repeated twice, and the results are shown in Table 2.
[0102] Comparative Example 3
[0103] The method described in Comparative Example 1 was carried out, except that the sample used in Example 6 was used instead of the sample used in Example 4; the test was repeated twice, and the results are shown in Table 2.
[0104] Table 1
[0105]
[0106] As can be seen from the results in Table 1, the method described in this invention does not require pretreatment of the test sample before digestion, and can complete the determination of sulfate content in the dispersant in a short time. Furthermore, this method is simple to operate, has a wide range of applications, small analytical errors, and avoids the use of large amounts of alcohol and ketone solvents, making it highly environmentally friendly and showing broad application prospects in the field of coal gasification water treatment technology.
[0107] Table 2
[0108]
[0109] Since both ICP and ion chromatography require digestion of the dispersant sample, which takes a long time, the method described in this application is compared with the gravimetric method. As can be seen from the results in Table 2, the method of this invention has a smaller relative error and higher accuracy compared with the gravimetric method.
[0110] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for rapidly determining the sulfate content in an ash water dispersant, characterized in that, The method includes the following steps: (1) Dilute the sample to be tested, then mix the partially diluted sample solution with hydrochloric acid solution, then mix the resulting reaction product with barium chloride solution, then mix the resulting reaction product with disodium magnesium ethylenediaminetetraacetate solution, then mix the resulting reaction product with ammonia-ammonium chloride buffer solution and chrome black T indicator, and finally titrate with EDTA standard titration solution until the solution color changes from wine red to bright blue, and record the volume V1 of the EDTA standard titration solution consumed; (2) Take an equal volume of water to the partially diluted sample solution described in step (1) and mix it with an equal volume of barium chloride solution and disodium magnesium ethylenediaminetetraacetate solution from step (1). Then, mix the resulting reaction product with an equal volume of ammonia-ammonium chloride buffer solution and chrome black T indicator from step (1). Then, titrate with EDTA standard titration solution until the solution color changes from wine red to bright blue. Record the volume V2 of the EDTA standard titration solution consumed. (3) Take another part of the diluted sample solution of the test, which is equal in volume to that of the partially diluted sample solution in step (1), and mix it with hydrochloric acid solution. Then, mix the resulting reaction product with an equal volume of ammonia-ammonium chloride buffer solution and chrome black T indicator from step (1), and then titrate it with EDTA standard titration solution until the solution color changes from wine red to bright blue. Record the volume V3 of the EDTA standard titration solution consumed. (4) Calculate the sulfate content in the sample to be tested using the following formula, expressed as a mass fraction ρ; Wherein, V1 is the volume of the EDTA standard titration solution consumed in step (1), in mL; V2 is the volume of the EDTA standard titration solution consumed in step (2), in mL; V3 is the volume of the EDTA standard titration solution consumed in step (3), in mL; C represents the concentration of the EDTA standard titration solution, in mol / L; m is the mass of the test sample in the partially diluted test sample solution, in grams.
2. The method according to claim 1, characterized in that, In step (1), the total amount of sulfate in the partially diluted test sample solution is less than 50 mg.
3. The method according to claim 2, characterized in that, In step (1), the total amount of sulfate in the partially diluted test sample solution is less than 30 mg.
4. The method according to any one of claims 1-3, characterized in that, In step (1), the volume ratio of the partially diluted sample solution to the hydrochloric acid solution is 100:0.5-5; and / or The concentration of the hydrochloric acid solution is 1-5 mol / L.
5. The method according to any one of claims 1-4, characterized in that, In step (1), the volume ratio of the partially diluted sample solution to the barium chloride solution is 100:10-50; and / or The concentration of the barium chloride solution is 0.01-0.05 mol / L.
6. The method according to any one of claims 1-5, characterized in that, In step (1), the volume ratio of the barium chloride solution to the disodium magnesium ethylenediaminetetraacetate solution is 1:0.5-1.5; and / or The concentration of the disodium magnesium ethylenediaminetetraacetate solution is 0.01-0.05 mol / L.
7. The method according to claim 1, characterized in that, In step (1), the volume ratio of the partially diluted test sample solution to the ammonia-ammonium chloride buffer solution is 100:10-20.
8. The method according to claim 1 or 7, characterized in that, The pH of the ammonia-ammonium chloride buffer solution is 7-10; and / or The ammonia-ammonium chloride buffer solution comprises ammonium chloride, ammonia water, and water.
9. The method according to claim 1, characterized in that, The amount of the Chrome Black T indicator used is 2-7 drops.
10. The method according to claim 1 or 9, characterized in that, The Chrome Black T indicator comprises Chrome Black T, hydroxylamine hydrochloride and ethanol, and the concentration of Chrome Black T in the Chrome Black T indicator is 1-5 g / L.