阅读说明：本技术 硫化物分析方法及自动分析仪 (Sulfide analysis method and automatic analyzer ) 是由 陈阳 罗志琴 李刚 于 2020-04-13 设计创作，主要内容包括：本发明公开了一种硫化物分析方法及硫化物自动分析仪,硫化物分析方法包括以下步骤：配制硫化物标准溶液,加入银盐和丙三醇,得到分散均匀的银胶体溶液,在预设波长处测定吸光度信号值,获得硫化物浓度-吸光度的标准工作曲线,将待测样品、银盐和丙三醇混合,得到分散均匀的银胶体溶液,在预设波长处测定其吸光度信号值V1,将V1代入标准工作曲线,计算得到待测样品中硫化物的浓度。本发明的硫化物分析方法,取样体积小,直接通过硫化物与银盐反应显色,操作简单,分析速度快,整个分析过程20min即可完成,避免在各个步骤中硫化物的损失,可实现快速、准确定量分析,且分析过程中采用的试剂无毒,对环境和操作人员友好。(The invention discloses a sulfide analysis method and an automatic sulfide analyzer, wherein the sulfide analysis method comprises the following steps: preparing a sulfide standard solution, adding silver salt and glycerol to obtain a uniformly dispersed silver colloidal solution, measuring an absorbance signal value at a preset wavelength to obtain a sulfide concentration-absorbance standard working curve, mixing a sample to be detected, the silver salt and the glycerol to obtain the uniformly dispersed silver colloidal solution, measuring an absorbance signal value V1 at the preset wavelength, substituting V1 into the standard working curve, and calculating to obtain the concentration of sulfide in the sample to be detected. The sulfide analysis method has the advantages of small sampling volume, direct color development through the reaction of sulfide and silver salt, simple operation, high analysis speed, and the whole analysis process can be completed within 20min, thereby avoiding the loss of sulfide in each step, realizing rapid and accurate quantitative analysis, and the reagent adopted in the analysis process is nontoxic and friendly to the environment and operators.)

1. A sulfide analysis method, comprising the steps of:

preparing sulfide standard solution, adding silver salt and glycerol to obtain uniformly dispersed silver colloid solution, measuring absorbance signal value at preset wavelength to obtain sulfide concentration-absorbance standard working curve,

mixing a sample to be detected, silver salt and glycerol to obtain a uniformly dispersed silver colloid solution, measuring an absorbance signal value V1 at the preset wavelength,

and substituting the V1 into the standard working curve, and calculating to obtain the concentration of sulfide in the sample to be detected.

2. The sulfide analysis method according to claim 1,

silver nitrate or silver acetate is used as the silver salt, and silver acetate is preferably used.

3. The sulfide analysis method according to claim 1,

the preset wavelength is 390 nm-430 nm.

4. The sulfide analysis method according to any one of claims 1 to 3,

when a sample to be detected is a complex water body containing turbidity or chromaticity, pretreating the sample to be detected, wherein the pretreatment comprises the following steps:

acidifying the sample to be detected to convert sulfide in the sample to be detected into H₂S, heating the sample to be detected and blowing to generate H₂And blowing off all S into the absorption-color development solution.

5. The sulfide analysis method according to claim 4,

the absorption-color development solution is a silver salt solution added with glycerol.

6. The sulfide analysis method according to claim 4,

the air blowing adopts an air pump to perform circular air blowing so as to increase H₂The absorption efficiency of S.

7. The sulfide analysis method according to claim 4,

the air blowing adopts constant-temperature homogeneous blowing at the temperature of 60 ℃, and the air blowing amount is 120 ml/min-300 ml/min.

8. The sulfide analysis method according to claim 4,

the acidification is performed by at least one of nitric acid, sulfuric acid, hydrochloric acid or phosphoric acid, and phosphoric acid is preferably used.

9. A sulfide automatic analyzer for carrying out the sulfide analysis method according to any one of claims 1 to 8,

the device comprises a gasification-pretreatment bottle with a heating device, wherein the gasification-pretreatment bottle is connected with an air pump and used for blowing air into the gasification-pretreatment bottle, an outlet of the gasification-pretreatment bottle is communicated with an absorption-color development pool, and an air outlet of the absorption-color development pool is connected with the air pump and used for realizing circular blowing.

Technical Field

The invention relates to the technical field of environmental monitoring and analysis, in particular to a sulfide analysis method, and further relates to an automatic sulfide analyzer for implementing the sulfide analysis method.

Background

The sulfide is the compound with the lowest valence state of sulfur element, and is not only present in smelting, petroleum, natural gas and some chemical raw materials, but also present in a plurality of natural water bodies and industrial wastewater. Sulfides are highly toxic and the presence of free or other forms of sulfides has a large impact on the quality of the environment.

Sulfides in water include soluble H₂S、HS^-、S^2-Soluble sulfides and acid-soluble metal sulfides are present in the suspension. Hydrogen sulfide easily escapes from water to the air, foul smell is generated, sensory indexes are deteriorated, and sulfide can consume oxygen in water in the water and cause aquatic organisms to die. Therefore, when the sulfide is detected in the environment, the water quality is often seriously polluted.

The water quality monitoring project is different according to different water body functions and types of pollution sources, and sulfide is an important index of water body pollution due to high sulfide toxicity. The method has practical significance in accurately and quickly measuring the sulfide content in the ecological environment, and can better provide real and reliable scientific basis for ecological environment protection and ecological environment management.

Currently, methods for detecting sulfides are commonly used, such as methylene blue spectrophotometry, iodometry, a sulfide ion selective electrode method, gas phase molecular absorption spectrometry, and flow injection-methylene blue spectrophotometry. Among these methods, methylene blue spectrophotometry (GB/T16489-1996), methylene blue spectrophotometry for measuring water quality sulfide, is a common analysis method in laboratories and is also a common method in the field of analysis at present. When the method is used for analysis, zinc acetate is required to be added as a fixing agent in the sampling process, and the sulfide concentration in a sample is quantitatively analyzed through the steps of acidification, heating, air blowing, absorption, color development, detection and the like. Since sulfides are extremely unstable and are easily oxidized, hydrogen sulfide is easily diffused. Therefore, in the process of water sample analysis, sulfide is lost due to excessive operation steps, and finally, the reliability of a test result is poor, and the precision is poor, which is also a common problem of the existing sulfide analysis method. In addition, the method is complicated to operate, zinc acetate is needed for precipitation in sampling and sample pretreatment, and operation steps needing attention are more; and the N, N-dimethyl-p-phenylenediamine has strong toxicity, has stimulation effect on eyes, mucous membranes, respiratory tracts and skin, is easy to cause methemoglobin to generate cyanoderma after being absorbed, can kill the human beings due to excessive inhalation, and has great harm to experimenters and environment.

Disclosure of Invention

The invention provides a sulfide analysis method and a sulfide automatic analyzer, and aims to solve the technical problems that the existing spectrophotometry is complex in operation and easy to cause sulfide loss when determining the content of sulfides, so that the accuracy of a detection result is poor, a used reagent is toxic, and the health of operators is harmed and the environment is polluted.

According to one aspect of the present invention, there is provided a sulfide analysis method comprising the steps of:

preparing sulfide standard solution, adding silver salt and glycerol to obtain uniformly dispersed silver colloid solution, measuring absorbance signal value at preset wavelength to obtain sulfide concentration-absorbance standard working curve,

mixing a sample to be detected, silver salt and glycerol to obtain a uniformly dispersed silver colloid solution, measuring an absorbance signal value V1 at a preset wavelength,

and substituting the V1 into the standard working curve, and calculating to obtain the concentration of sulfide in the sample to be detected.

Further, silver nitrate or silver acetate is used as the silver salt, and silver acetate is preferably used.

Further, the preset wavelength is 390 nm-430 nm.

Further, when the sample to be detected is a complex water body containing turbidity or chromaticity, the sample to be detected is pretreated, and the pretreatment step comprises:

acidifying the sample to be detected to convert sulfide in the sample to be detected into H₂S, heating the sample to be detected and blowing to generate H₂And blowing off all S into the absorption-color development solution.

Further, the absorption-color development solution is a silver salt solution added with glycerol.

Further, the blowing adoptsThe air pump performs circular blowing to increase H₂The absorption efficiency of S.

Furthermore, the air blowing adopts constant-temperature homogeneous blowing at the temperature of 60 ℃, and the air blowing amount is 120 ml/min-300 ml/min.

Further, the acidification is performed by at least one of nitric acid, sulfuric acid, hydrochloric acid or phosphoric acid, preferably by phosphoric acid.

According to another aspect of the invention, the automatic sulfide analyzer is used for implementing the sulfide analysis method, and comprises a gasification-pretreatment bottle with a heating device, wherein the gasification-pretreatment bottle is connected with an air pump and used for blowing air into the gasification-pretreatment bottle, an outlet of the gasification-pretreatment bottle is communicated with an absorption-color development pool, and an air outlet of the absorption-color development pool is connected with the air pump and used for realizing circular blowing.

The invention has the following beneficial effects:

according to the sulfide analysis method, silver salt and sulfide ions are reacted to generate yellow silver colloidal solution, the colloid is poor in uniformity and stability, therefore, glycerol is added as a dispersing agent, silver colloidal particles are uniformly dispersed under the action of the glycerol, the absorption intensity and the concentration are in a proportional relation at a preset wavelength, sulfide standard solutions with different concentrations are prepared, a sulfide concentration-absorbance standard working curve is drawn to obtain, the absorbance is measured after the same treatment steps are carried out on a sample and the standard solution, and the absorbance value is substituted into the standard working curve to obtain the concentration of sulfide in the sample. The sulfide analysis method has small sampling volume, only 1/10 of a methylene blue standard analysis method, does not need to use zinc acetate as a fixing agent, does not need complicated operation steps in a methylene blue spectrophotometry, directly performs color development through the reaction of sulfide and silver salt, has simple operation and high analysis speed, can complete the whole analysis process within 20min, avoids the loss of sulfide in each step, can realize quick and accurate quantitative analysis, meets the requirements of experiments and field quick analysis, adopts nontoxic reagents in the analysis process, and is friendly to environment and operators.

The automatic sulfide analyzer is a full-automatic integrated analyzer integrating pretreatment, absorption and detection, has high analysis speed, can complete the whole analysis process within 20 minutes, and does not need manual participation.

In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic flow diagram of a sulfide analysis method according to a preferred embodiment of the present invention;

FIG. 2 is a standard graph plotted in example 1;

FIG. 3 is an observation picture of a silver colloid solution formed by adding silver nitrate and glycerol to a sulfide sample under a high power microscope;

FIG. 4 is a photograph of a sulfide sample added with silver acetate and glycerol to form a silver colloid solution under a high power microscope.

Detailed Description

The embodiments of the invention will be described in detail below with reference to the accompanying drawings, but the invention can be embodied in many different forms, which are defined and covered by the following description.

As shown in fig. 1, the sulfide analysis method of the present embodiment includes the following steps:

preparing sulfide standard solution, adding silver salt and glycerol to obtain uniformly dispersed silver colloid solution, measuring absorbance signal value at preset wavelength to obtain sulfide concentration-absorbance standard working curve,

mixing a sample to be detected, silver salt and glycerol to obtain a uniformly dispersed silver colloid solution, measuring an absorbance signal value V1 at a preset wavelength,

and substituting the V1 into the standard working curve, and calculating to obtain the concentration of sulfide in the sample to be detected.

In the sulfide analysis method of the embodiment, a yellow silver colloidal solution is generated by reacting a silver salt with sulfide ions, and the colloid has poor uniformity and stability, so that glycerol is added as a dispersing agent, and silver colloidal particles are uniformly dispersed under the action of glycerol.

The main mechanism of action of the glycerol dispersed silver colloid is as follows: the silver ion aqueous solution is easily oxidized by air to generate silver oxide, the silver oxide is black precipitate and affects colorimetric measurement, and the glycerol has weak reducibility and can protect silver ions from being oxidized in the aqueous solution; the glycerol has the other function of enabling the system to be uniform, and during the reaction process of reducing Ag + into Ag in the aqueous solution, the glycerol can uniformly disperse the generated silver colloidal particles, and the silver powder is fine and is uniformly distributed. The solution is diverted from the colloid to or near the "true solution". The specific chemical reaction principle is as follows: sulfide in the sample escapes in the form of hydrogen sulfide under an acidic condition, and the hydrogen sulfide belongs to a reducing substance and can reduce silver ions into a silver simple substance so as to enable the solution to become a yellow colloid solution. The silver colloid solution generated by color development belongs to a liquid colloid, and the 'Tyndall phenomenon' can occur in the silver colloid solution. In the process of silver generation, under the condition of lacking glycerol, the tyndall phenomenon is very obvious, and when the lambert beer law is adopted, a precondition exists: the light absorbing substance is a non-scattering system. Therefore, the colloid has a serious deviation phenomenon when using the Lambert beer law, the addition of glycerol can make the system uniform, the suspension performance is increased, and the problem can be solved by turning the solution from the colloid to or approaching to a 'true solution'.

In the actual operation process, glycerol with the volume fraction of 20-70% relative to the volume fraction of the absorption-color development solution is adopted. Because the fluidity of the glycerol is poor, when more than 70% of glycerol is added, the fluidity of the whole solution is affected, and the background signal value of the color developing agent is tested at the moment, and the background signal is found to be abnormally high. If the amount of glycerol is less than 20%, the absorbed waste liquid has many small black particles, and the storage time of the whole developed solution is short. Preferably, the glycerol is 35 to 45 percent relative to the volume fraction of the absorption-coloration solution. The 35-45% of glycerol has good effect as a dispersant. More preferably, glycerol is used in an amount of 40% relative to the volume of the absorption-coloration solution.

Preferably, the preset wavelength is 390nm to 430 nm. Preparing sulfide standard solutions with different concentrations in a proportional relation between the absorption intensity of light at the wavelength of 390-430 nm and the sulfide concentration in the sample, drawing to obtain a sulfide concentration-absorbance standard working curve, performing the same treatment steps on the sample and the standard solutions, measuring the absorbance, and substituting the absorbance value into the standard working curve to calculate the sulfide concentration in the sample. The sulfide analysis method has small sampling volume, only 1/10 of a methylene blue standard analysis method, does not need to use zinc acetate as a fixing agent, does not need complicated operation steps in a methylene blue spectrophotometry, directly performs color development through the reaction of sulfide and silver salt, has simple operation and high analysis speed, can complete the whole analysis process within 20min, avoids the loss of sulfide in each step, can realize quick and accurate quantitative analysis, meets the requirements of experiments and field quick analysis, adopts nontoxic reagents in the analysis process, and is friendly to environment and operators.

In this embodiment, silver nitrate or silver acetate is used as the silver salt, and silver acetate is preferably used. The added silver salt is soluble silver salt, silver salt solid can be directly added into a sample to be detected, or silver salt solution can be prepared and added, silver ions react with hydrogen sulfide to generate silver colloid, silver colloid particles are uniformly dispersed in the solution under the dispersion action of glycerol, and silver nitrate or silver acetate is common soluble silver salt. Silver acetate is preferably used because silver oxide precipitates easily appear in silver nitrate in a sample solution, silver oxide is generated due to the fact that silver ions are oxidized by air in an aqueous solution, the silver oxide is black precipitate, false color is generated, the absorbance result of colorimetric measurement is influenced, and the accuracy of the test result is poor. Therefore, the reliability of the measurement result of selecting silver acetate is higher.

In this embodiment, when the sample to be detected is a complex water body containing turbidity or chromaticity, the sample to be detected further includes a pretreatment, and the pretreatment includes:

acidifying the sample to be detected to convert sulfide in the sample to be detected into H₂S, heating to standMeasuring the sample and blowing H₂And blowing off all S into the absorption-color development solution.

For standard solution and cleaner water body samples, pretreatment is not needed, silver salt and glycerol are directly added for determination, but for complex water bodies with higher turbidity or chromaticity, the interference is larger, the color development detection result is influenced, and pretreatment is needed firstly. Pretreatment for acidifying the sample to be tested by adding acid to generate H₂S gas, then H₂Expelling S gas into the absorption-coloration solution, absorbing H in the coloration solution₂And (3) reacting the S with silver salt to generate silver colloid, uniformly dispersing the silver colloid in the solution, and then measuring absorbance to obtain a concentration result of the sulfide. H formed by acidification₂S reacts with silver salt to generate colloid which can absorb H by absorption-color development solution₂S gas, adding silver salt and glycerol into the absorption-color development solution, wherein the absorption-color development solution is silver salt solution added with glycerol for simplifying the steps, and H is blown off by blowing₂S gas is directly absorbed and reacts, so that the analysis time can be shortened, and H can be avoided₂And S gas escapes, and the accuracy of an analysis result is higher.

In this embodiment, the air pump is used for circular air blowing to increase H₂The absorption efficiency of S. Blowing with clean air, nitrogen or other inert gas to carry H generated by acidification₂S gas to an absorption-color developing tank, H₂And S gas is absorbed by the absorption-color development solution, the gas used as blowing gas returns to the gas pump for circular blowing, and the circular blowing follows the gas quantity conservation law, namely the gas inflow is equal to the gas outflow.

In order to ensure the consistency of the using effect in different seasons and different areas, the scheme adopts constant-temperature homogeneous blowing at the temperature of 60 ℃, the air blowing amount is 120 ml/min-300 ml/min, preferably 180ml/min, and the air blowing time is preferably 5 min.

In this embodiment, at least one of nitric acid, sulfuric acid, hydrochloric acid, and phosphoric acid is used for the acidification, and phosphoric acid is preferably used. Acidification is used to convert the sulfide ions in the sample to be tested into H₂S gas is separated from the sample for detection, and thus is suitable forProvision of H by conventional acids⁺And (4) finishing. Since nitric acid and sulfuric acid have oxidizing properties, and can oxidize sulfides, which affects the detection result, and hydrochloric acid is easily volatilized, it is preferable to use phosphoric acid for acidification.

According to another aspect of the invention, there is also provided an automatic analyzer for implementing the sulfide analysis method, comprising a gasification-pretreatment bottle with a heating device, the gasification-pretreatment bottle is connected with an air pump for blowing air into the gasification-pretreatment bottle, the outlet of the gasification-pretreatment bottle is communicated with an absorption-color development pool, and the air outlet of the absorption-color development pool is connected with the air pump for realizing circular blowing.

When the automatic analyzer is used for analyzing sulfides, an absorption-color development solution containing silver salt and glycerol is added into an absorption-color development pool, the absorption-color development solution is placed at the detection position of a spectrophotometer, a sample to be detected and acid are added into a gasification-pretreatment bottle, after the bottle is sealed, a heating device and an air pump are started to blow air until the absorbance signal value measured by the spectrophotometer is stable, the air pump is closed, the absorbance signal value is recorded, and the standard curve equation is substituted to calculate the sulfide concentration. The automatic sulfide analyzer is a full-automatic integrated analyzer integrating pretreatment, absorption and detection, has high analysis speed, can complete the whole analysis process within 20 minutes, and does not need manual participation.

According to the automatic analyzer of the sulfide analysis method, hydrogen sulfide in the sample is expelled from the sample bottle in a blowing absorption mode and is absorbed by the absorption-color development solution, and the concentration of the sample is realized on the premise of ensuring the absorption efficiency, so that the accuracy and the stability of the low-concentration sample are met. Specifically, 10mL of sample is absorbed by 1mL of absorption-color development solution, the final detection volume is the volume of 1mL of absorption-color development solution, and the process can realize 10 times of concentration efficiency on the sample so as to meet the stability of the low-concentration sample. Compared with other methods, under the premise of 1/10 sample quantity, the method can realize considerable stability and accuracy.