Rapid detection method for sulfide in liquid phase sample in alkaline environment

Abstract

The invention discloses a rapid detection method for sulfides in an alkaline environment liquid phase sample, and belongs to the technical field of analytical chemistry, the rapid detection method comprises the following steps: S1, taking 25mL of an alkaline liquid phase sample to be detected, and adjusting the pH value of the alkaline liquid phase sample to be detected to 9-12; s2, adding 2mL of a 0.1% FeCl3 solution into the pH-adjusted alkaline liquid phase sample to be detected, and uniformly shaking to obtain a mixed solution; s3, observing the color and precipitation state of the mixed solution; and S4, comparing the mixed solution with a standard colorimetric solution, and determining the concentration range of the sulfide. The method has the advantages of simplicity and convenience in operation, low cost, high compatibility and visualization, and is suitable for industrial sites, environment monitoring and other scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical chemistry, and more particularly to a method for rapidly detecting sulfide in a liquid phase sample in an alkaline environment. Background Art

[0002] In the fields of chemical industry, environmental protection, energy, etc., sulfide (S 2 - etc.) are common pollutants or key process indicators; excessive concentrations can corrode equipment, affect catalyst activity, and even lead to non-compliance with environmental standards. However, existing methods for detecting sulfides have significant defects: mainstream spectrophotometric methods rely on acidic conditions, resulting in volatilization losses of sulfides in alkaline matrices (error rates as high as 28%) and unstable color development systems; carbonate, chloride ions, and heavy metal ions cause complex interferences, causing the detection error rate to exceed 40%; instruments such as gas chromatography are expensive (single sample > 1,000 yuan), and electrochemical sensors are susceptible to poisoning and failure (lifespan is only 30 days); traditional methods have a detection cycle of more than 90 minutes, which cannot meet the needs of industrial real-time control and emergency monitoring. In addition, domestic and international standards lack direct detection solutions for alkaline environments, and related patents have problems such as narrow detection range and weak anti-interference capabilities. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method for rapid detection of sulfide in liquid samples in an alkaline environment. The method realizes visual semi-quantitative detection of sulfide by changing the color of the solution. The method has the advantages of simple operation, low cost, strong compatibility and visualization, and is suitable for industrial sites, environmental monitoring and other scenarios.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for rapid detection of sulfide in an alkaline liquid sample comprises the following steps:

[0006] S1. Take 25 mL of the alkaline liquid sample to be tested and adjust its pH value to 9-12;

[0007] S2. Add 2 mL of 0.1% FeCl3 solution to the alkaline liquid sample to be tested after pH adjustment, shake well, and obtain a mixed solution;

[0008] S3. Observe the color and precipitation state of the mixed solution;

[0009] S4. Compare the color and precipitation state of the mixed solution with that of the standard colorimetric solution to determine the concentration range of sulfide.

[0010] Furthermore, in step S1, ammonia water or hydrochloric acid solution is used to adjust the pH.

[0011] Furthermore, in step S1, the alkaline liquid sample to be tested is a solution with a water-soluble negative divalent sulfide concentration ≥ 0 mg / L.

[0012] Furthermore, in step S3, the light source condition during observation is natural light or D65 standard light source; when 5°C ≤ observation temperature ≤ 40°C, the observation time is ≤ 30s; when the observation temperature is < 5°C, the observation time is 40-60s.

[0013] Furthermore, the steps for preparing the standard colorimetric solution are as follows:

[0014] (1) Using sulfide standard working solution, ammonia, and water as raw materials, the following standard control samples with different sulfide concentrations, all in a volume of 25 mL and a pH value of 9, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L;

[0015] Using sulfide standard working solution, ammonia and water as raw materials, the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 10, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L;

[0016] Using sulfide standard working solution, ammonia and water as raw materials, the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 11, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L;

[0017] Using sulfide standard working solution, ammonia and water as raw materials, the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 12, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L;

[0018] (2) Add 2 mL of 0.1% FeCl3 solution to each standard control sample and shake well to obtain a standard colorimetric solution. Observe and record the color and precipitation state of the standard colorimetric solution under natural light or D65 standard light source.

[0019] Furthermore, in step (2), when 5°C ≤ observation temperature ≤ 40°C, the observation time is ≤ 30s; when the observation temperature is < 5°C, the observation time is 40-60s.

[0020] In summary, the present invention has the following beneficial effects:

[0021] The present invention is based on the specific color reaction between ferric chloride (FeCl3) and sulfide in an alkaline environment. It realizes visual semi-quantitative detection of sulfide by changing the color of the solution. It is suitable for industrial sites, environmental monitoring and other scenarios, and has the following advantages:

[0022] (1) Fast response: The whole operation time is short and no complicated pre-processing is required;

[0023] (2) Low cost: using common reagents, the cost per sample is low;

[0024] (3) Strong compatibility: Applicable to alkaline systems with pH = 9 to 12;

[0025] (4) Visual operation: Semi-quantitative analysis can be achieved through colorimetry without the need for specialized instruments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a diagram of the standard colorimetric solution at a pH of 11 prepared in Example 1;

[0027] Figure 2 This is the appearance of the alkaline liquid sample to be tested in Example 1;

[0028] Figure 3 This is the appearance of the solution after the reaction in Example 1;

[0029] Figure 4 This is the appearance of the alkaline liquid sample to be tested in Example 2. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0031] The rapid detection method of sulfide in an alkaline environment liquid phase sample of the present invention comprises the following steps:

[0032] S1. Take 25 mL of the alkaline liquid sample to be tested and adjust its pH to 9-12 with ammonia water or hydrochloric acid solution;

[0033] S2. Add 2 mL of 0.1% FeCl3 solution to the alkaline liquid sample to be tested after pH adjustment, shake well, and obtain a mixed solution;

[0034] S3. Observe the color and precipitation of the mixed solution under natural light or D65 standard light source. When the observation temperature is 5°C ≤ ≤ 40°C, the observation time is ≤ 30 seconds. When the observation temperature is less than 5°C, the observation time is 40-60 seconds.

[0035] S4. Compare the mixed solution with a standard colorimetric solution in terms of solution color and precipitation state to determine the concentration range of sulfide; wherein the standard colorimetric solution is prepared by:

[0036] (1) Using sulfide standard working solution, ammonia, and water as raw materials, the following standard control samples with different sulfide concentrations, all in a volume of 25 mL and a pH value of 9, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L;

[0037] Using sulfide standard working solution, ammonia and water as raw materials, the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 10, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L;

[0038] Using sulfide standard working solution, ammonia and water as raw materials, the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 11, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L;

[0039] Using sulfide standard working solution, ammonia and water as raw materials, the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 12, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L;

[0040] (2) Add 2 mL of 0.1% FeCl3 solution to each standard control sample and shake well to obtain a standard colorimetric solution. Observe and record the color and precipitation state of the standard colorimetric solution under natural light or D65 standard light source. When the observation temperature is 5℃≤observation temperature≤40℃, the observation time is 30 s. When the observation temperature is <5℃, the observation time is 40-60 s.

[0041] Example 1

[0042] S1. Prepare standard colorimetric solution:

[0043] (1) 1000 mg / L BW20057-100-J-20 sulfide standard working solution (purchased from Tanmo Quality Inspection-Standard Material Center), ammonia water and water were used to prepare the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 11: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L, which were recorded as sample 1 to sample 8, respectively;

[0044] (2) Add 2 mL of 0.1% FeCl3 solution to each of samples 1 to 8, shake well, and obtain a standard colorimetric solution (e.g. Figure 1 Observe under natural light for 30 seconds and record the color of the standard colorimetric solution and the state of precipitation.

[0045] S2, take 25mL of alkaline liquid sample to be tested (taken from the sulfur-containing and ammonia conversion condensate in the water-coal slurry preparation conversion section, and pass it through a stripping tower, three-stage condensation, refined desulfurization, and compression condensation to obtain a liquid, such as Figure 2 As shown), the pH value was 8, and 10 wt% ammonia solution was added to adjust the pH value to 11; 2 mL of 0.1% FeCl3 solution was added and shaken; the solution color and precipitation state were observed under natural light for 30 seconds. The sample after the reaction was as shown in FIG. Figure 3 As shown, the color and precipitation state of the control standard colorimetric solution ( Figure 1 ) It can be seen that the sulfide concentration of the sample to be tested is between 20 and 25 mg / L.

[0046] Example 2

[0047] Take 25mL of alkaline liquid sample to be tested (taken from the sulfur-containing and ammonia-containing conversion condensate in the water-coal slurry preparation conversion section, and pass it through a stripping tower, three-stage condensation, refined desulfurization, and compression condensation to obtain a liquid, such as Figure 4 As shown), pH 11, add 2mL 0.1% FeCl3 solution, shake well; observe the color and precipitation state of the solution under natural light for 30s, and compare the color and precipitation state of the standard colorimetric solution ( Figure 1 ) It can be seen that the sulfide concentration of the sample to be tested is 5-10 mg / L.

[0048] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A rapid detection method for sulfide in an alkaline liquid sample, characterized in that: The following steps are involved: S1. Take 25 mL of the alkaline liquid sample to be tested and adjust its pH value to 9-12; S2. Add 2 mL of 0.1% FeCl3 solution to the alkaline liquid sample to be tested after pH adjustment, shake well, and obtain a mixed solution; S3. Observe the color and precipitation state of the mixed solution; S4. Compare the color and precipitation state of the mixed solution with that of the standard colorimetric solution to determine the concentration range of sulfide.

2. The method for detecting liquid-phase sulfide in an alkaline environment according to claim 1, wherein: In step S1, the pH is adjusted using aqueous ammonia or hydrochloric acid solution.

3. The method for rapid detection of sulfide in a liquid sample in an alkaline environment according to claim 1, characterized in that: In step S1, the alkaline liquid sample to be tested is a solution with a water-soluble negative divalent sulfide concentration of ≥0 mg / L.

4. The method for detecting liquid-phase sulfide in an alkaline environment according to claim 1, characterized in that: In step S3, the light source condition during observation is natural light or D65 standard light source; when 5°C ≤ observation temperature ≤ 40°C, the observation time is ≤ 30s; when the observation temperature is less than 5°C, the observation time is 40-60s.

5. The method for detecting liquid-phase sulfide in an alkaline environment according to claim 1, characterized in that: The preparation steps of the standard colorimetric solution are: (1) Using sulfide standard working solution, ammonia, and water as raw materials, the following standard control samples with different sulfide concentrations, all in a volume of 25 mL and a pH value of 9, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L; Using sulfide standard working solution, ammonia and water as raw materials, the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 10, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L; Using sulfide standard working solution, ammonia and water as raw materials, the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 11, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L; Using sulfide standard working solution, ammonia and water as raw materials, the following standard control samples with different sulfide concentrations, all with a volume of 25 mL and a pH value of 12, were prepared: 0 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, and 40 mg / L; (2) Add 2 mL of 0.1% FeCl3 solution to each standard control sample and shake well to obtain a standard colorimetric solution. Observe and record the color and precipitation state of the standard colorimetric solution under natural light or D65 standard light source.

6. The method for detecting liquid-phase sulfide in an alkaline environment according to claim 5, characterized in that: In step (2), when the observation temperature is 5°C ≤ ≤ 40°C, the observation time is ≤ 30s; when the observation temperature is < 5°C, the observation time is 40-60s.

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