CN111562155B - Detection method of sulfur ion concentration - Google Patents

Detection method of sulfur ion concentration Download PDF

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CN111562155B
CN111562155B CN202010548829.0A CN202010548829A CN111562155B CN 111562155 B CN111562155 B CN 111562155B CN 202010548829 A CN202010548829 A CN 202010548829A CN 111562155 B CN111562155 B CN 111562155B
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sulfur ions
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蒋良兴
王天意
彭阳
王君
刘芳洋
贾明
赖延清
李劼
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Central South University
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Abstract

The invention relates to a trace amount of sulfide ion (S)2‑) The field of analysis and detection, in particular discloses a visualization and photoelectrochemical detection method of the concentration of sulfur ions, which comprises the following steps: the sensing material coated with the active film is put into a solution to be detected containing sulfur ions for pretreatment; then, detecting the pretreated sensing material by adopting a visual colorimetric method or a photoelectrochemical method to obtain S in the solution to be detected2‑The ion concentration of (a); the active film is made of metal oxide or a heterojunction formed by the metal oxide and other semiconductor metals; the chemical formula of the metal oxide is MxOy‑z. The invention innovatively utilizes the metal oxide and the active thin film of the heterojunction thereof as a sensing material, and innovatively discovers the sensing material and S in a solution2‑The mutual surface interaction between the S and the S has an excellent linear correlation unexpectedly in visual colorimetry and photoelectrochemistry, and S in a solution can be realized2‑Visualization of and rapid, accurate, low-limit determination of photoelectrochemistry.

Description

Detection method of sulfur ion concentration
Technical Field
The invention relates to a trace amount of sulfide ion (S)2-) The field of analysis and detection, in particular to a rapid visual colorimetric and photoelectrochemical detection method for the concentration of sulfur ions.
Background
Quantitative analysis of sulfide ions is of great importance in the fields of environmental detection, biochemistry, food industry and the like. First, sulfur ion contamination can produce a paralytic effect on the respiratory system and a stimulatory effect on the skin. Long term exposure to high concentrations of S2-The environment can cause diabetes, cirrhosis, alzheimer's disease and down's syndrome, and even short-term exposure can cause symptoms such as nausea and dizziness. Under acidic conditions, S2-Will be protonated to form H2S, inhalation of small amounts of high concentrations of H2S can be fatal in a short time, and the H concentration is low2S has an effect on the eyes, respiratory system and central nervous system. Therefore, the method has important significance for quantitative analysis and detection of the sulfur ions.
At present, iodometry, methylene blue spectrophotometry, ion chromatography, capillary electrophoresis and the like are mainly adopted for detecting the sulfur ions. Among them, the iodometry is not suitable for the analysis of sulfides in sewage, and interferes with the measurement when water contains oxidizing substances, reducing substances and organic substances; when the methylene blue spectrophotometry is used for determining sulfide, S in a sample needs to be measured2-The method generates methylene blue dye with p-aminodimethylaniline in an acid solution containing ferric ions, and then obtains the concentration of the sulfur ions by measuring the absorbance, so that the operation is complex, and the detection effect in a complex sample is not ideal; ion chromatography and capillary electrophoresis require expensive equipment and the pretreatment step of the sample is cumbersome.
Disclosure of Invention
The invention mainly aims to provide a rapid visual colorimetric and photoelectrochemical detection method for the concentration of sulfur ions, aiming at solving the problems of expensive equipment, high detection cost, complex operation, low reliability, high time cost and the like of the existing sulfur ion detection method.
In order to achieve the purpose, the invention provides a method for detecting the concentration of sulfur ions, which comprises the steps of putting a sensing material coated with an active film into a solution to be detected containing sulfur ions for pretreatment;
then, detecting the pretreated sensing material by adopting a visual colorimetric method or a photoelectrochemical method to obtain S in the solution to be detected2-The ion concentration of (a);
the active film is made of metal oxide or a heterojunction formed by the metal oxide and other semiconductor metals;
the chemical formula of the metal oxide is MxOy-z(ii) a Wherein M is a metal element capable of forming a homometal oxide-sulfide heterojunction; the x is an integer not less than 1, and y-z is an integer not less than x/2.
The existing detection of the sulfur ions mainly adopts an iodometry method, a methylene blue spectrophotometry method, an ion chromatography method, a capillary electrophoresis method and the like, the technical limit of the prior art is overcome, and the method for measuring S based on visualization and photoelectric means is innovatively provided2-The concentration of the active carbon is completely new. The invention innovatively utilizes the metal oxide and the active thin film of the heterojunction thereof as a sensing material, and innovatively discovers the sensing material and S in a solution2-The mutual surface interaction between the S and the S has an excellent linear correlation unexpectedly in visual colorimetry and photoelectrochemistry, and S in a solution can be realized2-And rapid, accurate, low-volume determination of photoelectrochemistry.
In the invention, the M element is an element which has good thiophilic property and can form a heterojunction between the metal oxide and the sulfide thereof. Preferably, M is at least one of Bi, Pb, Cu, Zn, Ag, Hg and Cd; bi is more preferable.
Ax/2 ≦ y-z. A is the valence of M; preferably 1 to 4.
Preferably, in the metal oxide, 0 ≦ z < 1.
The invention further researches and discovers that the oxygen of the metal oxide is deficient by oxygenCompound (0)<z<1). It was found that oxygen deficient oxides contribute to further improvement of S2-The accuracy of the measurement is improved, and the test error is reduced.
Preferably, the metal oxide is Bi2O3-z、PbO2-z、CdO1-z、CuO1-z、ZnO1-zAt least one of (1).
The research of the invention finds that the thickness of the active film is 10-2000 nm.
In the invention, the sensing material comprises a substrate and an active film coated on the surface of the substrate.
Preferably, the substrate is a planar substrate.
The substrate is a conductive substrate or a non-conductive substrate.
Preferably, the conductive substrate is at least one of FTO conductive glass, ITO conductive glass, PI, or transparent conductive oxide.
Preferably, the non-conductive substrate is at least one of stainless steel, glass, corundum, quartz and ceramic substrate.
The research of the invention finds that the active film can be constructed by the existing means, but the research finds that the active film constructed by at least one of the chemical water bath method, the sol-gel method, the magnetron sputtering method and the solvothermal method is more beneficial to the S2-The measurement of (1).
Preferably, the active film is prepared by the chemical water bath method. Research shows that the structural characteristics of the active thin film constructed by the method are more beneficial to S2-The measurement of (1).
Further preferably, the preparation process of the sensing material comprises the following steps: pretreating the substrate, depositing the hydroxide of M, the oxide of M or the organic complex of M on the surface of the substrate, and annealing to obtain the material. For example, bismuth salt, complexing agent and auxiliary agent are mixed to obtain precursor solution, and then the precursor solution is coated on a substrate and annealed to obtain the thin film. The complexing agent is citric acid, and the auxiliary agent is triton X-100. Or depositing a solution containing bismuth salt and alkali liquor on a substrate and then annealing. The annealing temperature is, for example, 300 to 600 ℃, preferably 350 to 500 ℃.
The measuring method of the invention is that the sensing material is put into the solution to be measured and is pretreated to lead the active film and the S in the solution to be2-And (4) interaction.
Preferably, the pretreatment temperature is 10 ℃ to 60 ℃.
Preferably, the pH value of the solution in the pretreatment process is 4-9.
Preferably, the pretreatment time is 5s to 60 min.
Preferably, the step of detecting the concentration of the sulfur ions by the visual colorimetry comprises the following steps:
comparing the pretreated sensing material with a standard colorimetric card through naked eyes to obtain the concentration of the sulfur ions in the solution to be detected;
or photographing and sampling the surface of the pretreated sensing material, reading a photograph gray value (G) by adopting image processing software, and determining the concentration of the sulfur ions in the solution to be detected by contrasting a standard colorimetric curve with one-to-one correspondence relationship between the concentration (C) of the sulfur ions and the gray value.
In the invention, the detection steps of the photoelectrochemistry detection method are as follows:
compounding an active film on a conductive substrate, taking the pretreated sensing material as a working electrode, constructing a three-electrode system with an auxiliary electrode and a reference electrode, detecting the photoresponse current of the sensing electrode under the irradiation of a light source and a certain bias voltage, and obtaining the concentration of the sulfur ions in the solution to be detected by comparing the actually measured photoresponse current with a standard curve.
Preferably, the auxiliary electrode is one of a platinum electrode and a graphite electrode.
Preferably, the reference electrode is one of a saturated calomel electrode or a silver chloride electrode.
Preferably, the applied bias value is 0V to 1.2vvs.
Preferably, the light source is one of sunlight, a xenon lamp, a halogen tungsten lamp, a metal halide lamp, an incandescent lamp, a fluorescent lamp, an LED lamp, a mercury lamp, and a laser.
Preferably, the power of the light source is 1mW/cm2～3000mW/cm2。
Preferably, the standard curve for photoelectrochemical detection is a linear fit curve of the photoresponse current and the sulfur ion concentration or the sulfur ion concentration logarithm value, or a linear fit curve of the change value of the photoresponse current (i.e. the photoresponse current of the photoelectric sensing electrode pretreated in the sulfur ion-containing blank liquid-the photoresponse current of the photoelectric sensing electrode pretreated in the sulfur ion-free standard liquid) and the sulfur ion concentration or the sulfur ion concentration logarithm value.
The invention discloses a preferable detection method of the concentration of sulfur ions, which comprises the following steps:
(1)MxOy-zpreparation of sensing electrode
The method comprises the steps of conducting substrate pretreatment, precursor solution preparation and sensing electrode material growth.
(2) Drawing of colorimetric cards and standard colorimetric curves
Preparing standard solutions containing sulfur ions with different concentrations.
Mixing M prepared in step (1)xOy-zAnd (3) putting the sensing electrode into a standard solution containing sulfur ions for pretreatment. Taking out MxOy-zAfter the sensing electrode is dried, a photo is taken, and colorimetric cards with different sulfur ion concentrations are drawn. And then, reading the gray value of the colorimetric image by adopting picture software, and establishing a standard colorimetric curve of the gray value (G) and the sulfur ion concentration (C).
(3) Drawing standard curve for detecting sulfur ions by photoelectrochemical method
Putting the pretreated M in the standard solution containing the sulfur ions in the step (2)xOy-zThe sensing electrode is a working electrode, a three-electrode system is constructed in a photoelectrochemistry test solution together with an auxiliary electrode and a reference electrode, the photoresponse current of the working electrode is detected under the irradiation of a light source and a certain bias voltage, the photoresponse current and the concentration of sulfur ions are used for linear fitting, and a standard curve is drawn.
(4) Colorimetric method and photoelectrochemical method for detecting sulfur ions in water body
Mixing M prepared in step (1)xOy-zAnd the sensing electrode is put into a solution to be detected containing sulfur ions for pretreatment. Pre-treated MxOy-zAnd comparing the image of the sensing electrode with a colorimetric card by adopting a visual inspection method, or comparing the gray value of the image with a standard colorimetric curve to obtain the concentration of the sulfur ions in the solution to be detected.
Detecting the pretreated M by using the photoelectric response current testing method in the step (3)xOy-zAnd (3) comparing the actual measurement photoresponse current with the standard curve to obtain the concentration of the sulfur ions in the solution to be measured.
Preferably, in the step (1): cutting the conductive substrate into 2cm x 3cm, cleaning with surfactant, ultrasonic cleaning with ultrapure water, ethanol, acetone, and ultrapure water for 15min, respectively, and ultrasonic cleaning with N2It was blow-dried and then cleaned with a surface plasma cleaner. The conductive substrate comprises FTO conductive glass or ITO conductive glass. The cleaning time of the plasma cleaning machine is 5-10 min. The M isxOy-zThe preparation method of the sensing electrode material comprises a chemical water bath method, a sol-gel method, a magnetron sputtering method, a solvothermal method and the like. The bismuth oxide film is a heterojunction formed by pure bismuth oxide, bismuth oxide and other semiconductor materials.
Preferably, in the step (2): the pH value of the standard solution containing the sulfur ions is 4-9. The concentration of the sulfur ions in the standard solution containing the sulfur ions is 0.1 mu mol/L-10 mmol/L. The pretreatment time of the sensing electrode in the standard solution containing sulfur ions is 5 s-60 min, and the pretreatment temperature is 10-60 ℃.
Preferably, in the step (3): the light source is one of the sun, a xenon lamp, a halogen tungsten lamp, a metal halogen lamp, an incandescent lamp, a fluorescent lamp, an LED lamp, a mercury lamp and a laser. The luminous power of the light source is 1mW/cm2～3000mW/cm2. The additional bias voltage is 0V-1.2 Vvs. The auxiliary electrode comprises a platinum electrode or a graphite electrode, and the reference electrode comprises a silver chloride electrode or a saturated calomel electrode. The photoelectrochemical measurementThe test solution includes phosphate buffered saline, borate buffered saline, sodium sulfate solution or sodium hydroxide solution. The concentration of the photoelectrochemistry test solution is 0.001 mol/L-2 mol/L.
The technical concept of the invention is as follows:
the colorimetric detection is based on the color change of a chromogenic substrate, is related to the content of a substance to be detected, and achieves the aim of quantitatively detecting the concentration of the substance to be detected. The photoelectrochemical detection is that a photoelectrochemical active material is modified on an electrode to prepare a photoelectric sensing electrode, the photoelectric sensing electrode and a corresponding photoelectric combined device form a current loop, and the change of a photoelectric signal is caused by the interaction between a substance to be detected and the photoelectric material, so that the concentration change of the substance to be detected can be quantitatively analyzed.
The invention provides a visual and photoelectrochemical detection method for sulfur ion concentration in water, wherein an active film is Bi2O3-zThin film material is taken as an example, the Bi is adopted2O3-zThe film material is a sensing electrode; and adding Bi2O3-zAfter the film is put into a solution containing sulfur ions for soaking for a period of time, Bi is generated on the surface of the film2S3(as in equation (a)). Bi2O3-zGenerally a white or yellow thin film material, and Bi2S3Black, so that Bi is formed on the surface2S3The color of the film material is significantly changed. In addition, Bi2S3As a semiconductor with narrow band gap, Bi can be increased remarkably2O3-zAbsorption of visible light, and Bi2O3-zAnd Bi2S3The formed heterostructure can promote the separation of carriers and improve the photoelectric response of the material.
Bi2O3-z+(3-z)S2-+(3-z)H2O＝Bi2S3↓+(6-2z)OH- (a)
Different concentrations of sulfur ions in the solution to be measured, Bi2O3Surface generated Bi2S3The amount is correspondingly changed, so that the color of the material is changed differently, and the photoelectric response performance of the material is also different, not only is Bi2O3-zAnd S2-Can establish the linear corresponding relation of the film color, the photoresponse current and the sulfur ion concentration, and adopts Bi based on the linear corresponding relation2O3The thin film electrode can detect sulfur ions in the solution.
Compared with the prior art, the invention has the following beneficial effects:
the method adopts visual detection of the sulfur ions in the solution, and has the advantages of simplicity, practicability, low cost and high detection speed;
the method adopts photoelectrochemistry to detect the sulfur ions in the solution, the excitation source is a light source, the response signal is current, the excitation source and the response signal are completely separated and do not interfere with each other, and the background signal is low;
the invention adopts the photoelectrochemistry method to detect the sulfur ions in the solution, can detect the photoresponse current of the photoelectric sensing electrode on site in real time, has high signal response speed and can realize the rapid and on-line detection of the concentration of the sulfur ions;
the strategy of photoelectrochemical detection of the sulfur ions is that the sulfur ions in the solution are vulcanized with a photoelectric sensing material, so that the color of the surface of the film is changed, visual color comparison can be realized, and the oxide and the sulfide form a heterojunction, so that the photoelectric response current is improved, namely, the detection process is a signal enhancement process and has the characteristics of signal readability, diversity, high sensitivity, strong anti-interference capability and the like;
the detection range of the invention for detecting the sulfur ions in the liquid is 0.1 mu mol/L-10mmol/L, which is lower than the detection range of the traditional detection method, and the invention is very suitable for the direct detection of the trace sulfur ions in the water body.
Drawings
FIG. 1 shows Bi obtained in step (1) of example 1 of the present invention2O3Wherein fig. 1a is a topography at low resolution and fig. 1b is a topography at high resolution.
FIG. 2 shows Bi obtained in step (1) of example 1 of the present invention2O3Phase analysis XRD pattern of.
FIG. 3 shows Bi in step (2) of example 1 of the present invention2O3Thin film photoelectrochemical sensorThe photoresponse current curve (a; left graph) of the change of the concentration of the sulfide ions and the standard curve (b; right graph) thereof.
FIG. 4 shows Bi obtained in step (1) of example 2 of the present invention2O2.33SEM image of (d).
FIG. 5 shows Bi obtained in step (1) of example 2 of the present invention2O2.33Phase analysis XRD pattern of. From XRD, it can be observed that the prepared bismuth oxide contains oxygen defects.
FIG. 6 shows Bi in step (2) of example 2 of the present invention2O2.33The light response current curve (a) of the thin film photoelectrochemical sensor and the standard curve (b) thereof are changed along with the change of the concentration of the sulfur ions.
FIG. 7 shows Sb obtained in step (1) of comparative example 1 according to the present invention2O3SEM image of (d).
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the claims.
Example 1
Bi2O3Preparation of film electrode and photoelectrochemical detection of sulfur ion concentration in water body by using film electrode
The method for rapidly detecting the concentration of sulfur ions in water by photoelectrochemistry provided by the embodiment of the invention deposits Bi by a chemical water bath method2O3The film is taken as an example of a working electrode and mainly comprises the following steps:
(1) preparation of photoelectric sensing electrode
Pretreatment of conductive substrate
Cutting FTO into 2cm x 3cm, cleaning with surfactant, ultrasonic cleaning with ultrapure water, ethanol, acetone, and ultrapure water for 15min, respectively, and ultrasonic cleaning with N2It was blow-dried and then cleaned with a surface plasma cleaner for 5 min.
Preparation of photoelectric sensing electrode material
2.91g of bismuth nitrate was weighed into a beaker, to which was added 2mL of concentrated nitric acid, followed by deionized water to make 60mL of bismuth nitrate solution. Adding 3mL of triethanolamine, then dropwise adding a saturated sodium hydroxide solution into the solution, and adjusting the pH value to 11 to obtain a bismuth nitrate precursor solution.
And (3) putting the pretreated conductive substrate into the precursor solution, depositing for 60min at 60 ℃, then washing for several times by using deionized water, and drying. And carrying out post-annealing treatment on the obtained film in a tubular furnace, wherein the annealing temperature is 350 ℃, the heat preservation time is 1h, and the heating rate is 5 ℃/min.
FIG. 1 shows Bi prepared2O3The film appearance can be seen as Bi2O3The film is composed of nanosheets with uniform sizes, and the nanosheets are arranged in order. The film thickness was 900 nm.
FIG. 2 shows the Bi obtained2O3The X-ray diffraction pattern of (A) shows that Bi is present2O3The crystallinity is good and completely matched with PDF cards.
(2) Drawing of standard curve
Preparing Na under different concentration gradients2S solutions, each of which is a volume of Na of different concentrations2S solution was added to 1M Na2SO4In the solution, the detected Na is obtained2SO4The concentrations of sulfur ions in the solution are respectively as follows: 0.1. mu. mol/L, 1. mu. mol/L, 10. mu. mol/L, 100. mu. mol/L, 1mmol/L, 10 mmol/L. Wherein dilute H is added2SO4Regulating Na2SO4The pH of the solution was 4.
The Bi for detecting the sulfur ions prepared in the step (1)2O3The film is used as a working electrode, the graphite electrode is used as an auxiliary electrode, the saturated calomel electrode is used as a reference electrode, and the electrodes are respectively arranged in Na containing sulfur2SO4A three-electrode system was constructed in standard solution. Soaking the working electrode in standard sulfur ion solution at 30 deg.C for 20min under irradiation of xenon lamp light source (light power of 300 mW/cm)2) And performing electrochemical analysis under the bias voltage of 0.5Vvs. RHE, fitting a relation curve between the photoresponse current (I) and the sulfur ion concentration (C) (the right graph of FIG. 3) according to the difference of photoresponse currents under different sulfur ion concentrations by using an I-t curve as an experimental basis (the left graph of FIG. 3), wherein the linear detection range of the sulfur ions is 0.1 mu mol/L-10 mmol/L.
The left diagram of FIG. 3 shows Bi2O3The photocurrent response curve of the photoelectric sensing electrode in the standard sulfur ion solution with different concentrations shows that the photocurrent also increases with the gradual increase of the sulfur ion concentration. The right graph of fig. 3 is a linear curve fitted with current and concentration, and it can be seen that the current has a better linear relationship with the concentration of sulfur ions. The photoresponse current I and the sulfur ion concentration C have the relation of I-0.0.5499C +5.72334, and the linear correlation coefficient R2＝0.97883。
(3) Photoelectrochemical detection of sulphur ions in water
50mL of the test solution was taken and 1M Na was added thereto2SO4The Bi prepared in the step (1)2O3And soaking the membrane electrode in the solution to be measured at 30 ℃ for 10 min. With pretreated Bi2O3The photoelectric sensing electrode is a working electrode, the graphite electrode is used as an auxiliary electrode, and the saturated calomel electrode is used as a reference electrode to construct a three-electrode system. Under the irradiation of a xenon lamp light source (the light power is 300 mW/cm)2) The photo-response current of the photo-sensing electrode was measured in situ at a bias voltage of 0.5vvs. The obtained photoresponse current is compared with the standard curve in the step (2) to obtain the concentration (C) of the sulfur ions in the solution to be detectedm)。
The average value (C) of the concentration of the sulfur ions in the solution to be measured is obtained after the system of the first embodiment of the invention is adopted for measuring three timesm) 3.21. mu. mol/L, and the average value of the sulfur ion concentration (C) obtained after three measurements by ion chromatography0) 3.07. mu. mol/L are substantially identical. The relative error δ of this method was calculated to be 4.36%.
Example 2
Bi2O2.33Preparation of film electrode and photoelectrochemical detection of sulfur ion concentration in water body by using film electrode
Method for detecting concentration of sulfur ions in water body, and deposition of Bi by chemical water bath method2O2.33The film is taken as an example of a working electrode and mainly comprises the following steps:
(1) preparation of the electrodes
Pretreatment of conductive substrate
Cutting ITO into 5cm by 5cmCleaning with surfactant, ultrasonic cleaning with ultrapure water, ethanol, acetone, and ultrapure water for 15min, respectively, and cleaning with N2It was blow-dried and then cleaned with a surface plasma cleaner for 5 min.
Preparation of precursor solution
A certain amount of nitric acid is measured and slowly added into 4mL of deionized water to obtain solution A, and then 1g of bismuth nitrate is added. Under the condition of continuous stirring, a certain amount of triton X-100 and citric acid are added into 2mL of absolute ethyl alcohol to obtain solution B. Subsequently, the solution B is added dropwise into the solution A and stirred for 4 hours to obtain a stable solution. Finally, the solution is aged for 12h for standby.
Preparation of film
And (3) putting the ITO substrate into a spin coater, and dropwise adding a proper amount of precursor solution for spin coating to obtain the film. The film was placed in a muffle furnace and annealed at 500 ℃.
FIG. 4 shows the morphology of the prepared film, and it can be seen that Bi2O2.33The film is composed of nanowires with uniform size and is orderly arranged. The film thickness was 50 nm.
FIG. 5 shows an X-ray diffraction pattern of the prepared film, corresponding to Bi2O2.33The PDF card and the substrate ITO have diffraction peaks, and the prepared film has oxygen defects in an XRD (X-ray diffraction) pattern.
(2) Drawing of standard curve
Preparing Na under different concentration gradients2S solutions, each of which is a volume of Na of different concentrations2S solution was added to 1M Na2SO4In the solution, the detected Na is obtained2SO4The concentrations of sulfur ions in the solution are respectively as follows: 0.1. mu. mol/L, 1. mu. mol/L, 10. mu. mol/L, 100. mu. mol/L, 1mmol/L, 10 mmol/L. Wherein dilute H is added2SO4Regulating Na2SO4The pH of the solution was 4.
The Bi for detecting the sulfur ions prepared in the step (1)2O2.33The film is used as a working electrode, the graphite electrode is used as an auxiliary electrode, the saturated calomel electrode is used as a reference electrode, and the electrodes are respectively arranged in Na containing sulfur2SO4Construction of three-electrode system in standard solution. Soaking the working electrode in standard sulfur ion solution at 30 deg.C for 20min under irradiation of xenon lamp light source (light power of 300 mW/cm)2) Electrochemical analysis is carried out under the bias voltage of 0.5Vvs. RHE, an I-t curve is taken as an experimental basis (figure 6a), a relation curve (figure 6b) between the photoresponse current (I) and the sulfur ion concentration (C) is fitted according to the difference of photoresponse currents under different sulfur ion concentrations, and the linear detection range of the sulfur ions is 0.1 mu mol/L-10 mmol/L.
Fig. 6b is a linear curve fitted with current and concentration, and it can be seen that the current has a better linear relationship with the concentration of sulfur ions. The photoresponse current I and the sulfur ion concentration C have the relation of I-0.34336C +6.47565, and the linear correlation coefficient R2＝0.99334。
The linear dependence of current on concentration is greater than that of example one, and the photocurrent density is significantly increased, the presence of vacancies increasing the active film' S contribution to S2-The accuracy of ion monitoring increases the photocurrent density of the thin film.
(3) Photoelectrochemical detection of sulphur ions in water
50mL of the test solution was taken and 1M Na was added thereto2SO4The Bi prepared in the step (1)2O2.33And soaking the membrane electrode in the solution to be measured at 30 ℃ for 10 min. With pretreated Bi2O2.33The photoelectric sensing electrode is a working electrode, the graphite electrode is used as an auxiliary electrode, and the saturated calomel electrode is used as a reference electrode to construct a three-electrode system. Under the irradiation of a xenon lamp light source (the light power is 300 mW/cm)2) The photo-response current of the photo-sensing electrode was measured in situ at a bias voltage of 0.5vvs. The obtained photoresponse current is compared with the standard curve in the step (2) to obtain the concentration (C) of the sulfur ions in the solution to be detectedm)。
The average value (C) of the concentration of the sulfur ions in the solution to be measured is obtained after the system of the first embodiment of the invention is adopted for measuring three timesm) 3.21. mu. mol/L, and the average value of the sulfur ion concentration (C) obtained after three measurements by ion chromatography0) 3.15. mu. mol/L are substantially identical. The relative error δ of this method was calculated to be 1.20%.
Example 3
Bi2O3Preparation of thin film electrode and visual colorimetric detection of sulfur ion concentration in water body
The method for rapidly and visually detecting the concentration of sulfur ions in water through colorimetry provided by the embodiment of the invention is used for depositing Bi by a chemical water bath method2O3The film is taken as an example of a working electrode and mainly comprises the following steps:
(1) preparation of films
Pretreatment of non-conductive substrates
Cutting glass into 2cm x 3cm, cleaning with surfactant, ultrasonic cleaning with ultrapure water, ethanol, acetone, and ultrapure water for 15min, respectively, and ultrasonic cleaning with N2It was blow-dried and then cleaned with a surface plasma cleaner for 5 min.
Preparation of thin film Material
2.91g of bismuth nitrate was weighed into a beaker, to which was added 2mL of concentrated nitric acid, followed by deionized water to make 60mL of bismuth nitrate solution. Adding 3mL of triethanolamine, then dropwise adding a saturated sodium hydroxide solution into the solution, and adjusting the pH value to 11 to obtain a bismuth nitrate precursor solution.
And (3) putting the pretreated non-conductive substrate into the precursor solution, depositing for 120min at 60 ℃, then washing for several times by using deionized water, and drying. And carrying out post-annealing treatment on the obtained film in a muffle furnace, wherein the annealing temperature is 350 ℃, the heat preservation time is 1h, and the heating rate is 10 ℃/min.
(2) Drawing of standard color comparison card
Bi prepared in the step (1)2O3The membrane electrode is soaked in standard solution at 25 deg.C for 10 min. And taking out the film, drying, photographing and sampling the film, reading the gray value of the film by photoshop, and fitting the relationship between the gray value and the concentration of the sulfur ions. And printing a standard color comparison card according to the obtained fitting curve.
(3) Visual detection of sulfur ions in water
50ml of the test solution was taken and 1M Na was added thereto2SO4The Bi prepared in the step (1)2O3The membrane electrode is placed in the solution to be measuredSoaking at 25 deg.C for 10 min. And comparing the soaked film with a standard colorimetric card, and reading the concentration of sulfur ions in the solution.
The average value (Cm) of the concentration of the sulfur ions in the solution to be measured obtained after the three times of measurement by adopting the system of the second embodiment of the invention is 2.70 mu mol/L, and basically matches with the average value (Co) of the concentration of the sulfur ions obtained after the three times of measurement by adopting an ion chromatograph, and the relative error delta of the method is calculated to be 7.80 percent.
Comparative example 1
Sb2O3Preparation of film electrode and photoelectrochemical detection of sulfur ion concentration in water body by using film electrode
The embodiment of the invention provides a method for rapidly detecting the concentration of sulfur ions in a water body by photoelectrochemistry, which is used for depositing Sb by a chemical water bath method2O3The film is taken as an example of a working electrode and mainly comprises the following steps:
(1) preparation of the electrodes
Pretreatment of conductive substrate
Cutting FTO into 5cm × 5cm pieces, cleaning with surfactant, ultrasonic cleaning with ultrapure water, ethanol, acetone, and ultrapure water for 15min, respectively, and ultrasonic cleaning with N2It was blow-dried and then cleaned with a surface plasma cleaner for 5 min.
Preparation of precursor solution
0.684g of antimony chloride (SbCl) are weighed out3) Dissolved in 20ml of concentrated hydrochloric acid, and 100ml of ultrapure water and 3ml of triethanolamine (C) were added6H15O3N), to prepare clear SbCl3The saturated sodium hydroxide (NaOH) solution was added dropwise to SbCl via a dropper3In solution, until the pH of the solution reached 7.8, the solution was stirred until it became clear and transparent.
Preparation of film
And vertically placing the previously cleaned FTO substrate into the prepared solution. The whole beaker is placed in a water bath kettle at 60 ℃ to be heated for 15 min. During which the solution was slowly stirred by a stirrer. Sb2O3Successfully deposited on FTO conductive substrates. Taking out the film, and cleaning with deionized waterDrying the surface of the film at normal temperature.
FIG. 7 shows Sb2O3The morphology of the prepared film can show that Sb is2O3The film is composed of prismatic nano arrays with uniform size and is arranged orderly.
(2) Drawing of standard curve
Preparing Na under different concentration gradients2S solutions, each of which is a volume of Na of different concentrations2S solution was added to 1M Na2SO4In the solution, the detected Na is obtained2SO4The concentrations of sulfur ions in the solution are respectively as follows: 0.1. mu. mol/L, 1. mu. mol/L, 10. mu. mol/L, 100. mu. mol/L, 1mmol/L, 10 mmol/L. Wherein dilute H is added2SO4Regulating Na2SO4The pH of the solution was 4.
The Sb for detecting the sulfur ions prepared in the step (1) is added2O3The film is used as a working electrode, the graphite electrode is used as an auxiliary electrode, the saturated calomel electrode is used as a reference electrode, and the electrodes are respectively arranged in Na containing sulfur2SO4A three-electrode system was constructed in standard solution. Soaking the working electrode in standard sulfur ion solution at 30 deg.C for 20min under irradiation of xenon lamp light source (light power of 300 mW/cm)2) The electrochemical analysis is carried out under the bias voltage of 0.5Vvs. RHE, and the linear detection range of the sulfur ions is 0.1 mu mol/L-10 mmol/L. The relation between the photoresponse current I and the sulfur ion concentration C is 0.3845C +7.954, and the linear correlation coefficient is only R2＝0.6468。
It can be seen that, without using the metal oxide thin film or the metal oxide-deficient oxide thin film of the present invention as a sensing material, the obtained light-spot response current I has a linear dependence of the sulfur ion concentration C, which is much different from that of embodiment 1 and embodiment 2.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be construed as the protection scope of the present invention.

Claims (14)

1. A method for detecting the concentration of sulfur ions is characterized in that: the sensing material coated with the active film is put into a solution to be detected containing sulfur ions for pretreatment;
then, detecting the pretreated sensing material by adopting a visual colorimetric method or a photoelectrochemical method to obtain S in the solution to be detected2-The ion concentration of (a);
the material of the active film is metal oxide; the chemical formula of the metal oxide is Bi2O3-z(ii) a 0 is as described<z<1；
The visual colorimetric method for detecting the concentration of the sulfur ions comprises the following steps:
comparing the pretreated sensing material with a standard colorimetric card through naked eyes to obtain the concentration of the sulfur ions in the solution to be detected;
or, photographing and sampling the surface of the pretreated sensing material, reading a gray value (G) of the photograph by adopting image processing software, and determining the concentration of the sulfur ions in the solution to be detected by contrasting a standard colorimetric curve with one-to-one correspondence relationship between the concentration (C) of the sulfur ions and the gray value;
the detection steps of the photoelectrochemistry detection method are as follows:
compounding an active film on a conductive substrate, using the pretreated sensing material as a working electrode, constructing a three-electrode system with an auxiliary electrode and a reference electrode, detecting the photoresponse current of the sensing electrode under the irradiation of a light source and a certain bias voltage, and obtaining the concentration of the sulfur ions in the solution to be detected by comparing the actually measured photoresponse current with a standard curve.
2. The method for detecting a sulfide ion concentration according to claim 1, comprising: the metal oxide is Bi2O2.33。
3. The method for detecting a sulfide ion concentration according to claim 1, comprising: the thickness of the active thin film is 10-2000 nm.
4. The method for detecting a sulfide ion concentration according to claim 1, comprising: the active film is obtained by at least one of a chemical water bath method, a sol-gel method, a magnetron sputtering method and a solvothermal method.
5. The method for detecting a sulfide ion concentration according to claim 1, comprising: the sensing material comprises a substrate and an active film coated on the surface of the substrate;
the substrate is a conductive substrate or a non-conductive substrate.
6. The method for detecting a sulfide ion concentration according to claim 5, comprising: the conductive substrate is at least one of FTO conductive glass, ITO conductive glass, PI and transparent conductive oxide.
7. The method for detecting a sulfide ion concentration according to claim 5, comprising: the non-conductive substrate is at least one of stainless steel, glass, corundum, quartz and ceramic substrate.
8. The method for detecting a sulfide ion concentration according to claim 1, comprising: the pretreatment temperature is 10-60 ℃.
9. The method according to claim 8, wherein the concentration of sulfur ions is determined by: the pH value of the solution is 4-9.
10. The method according to claim 8, wherein the concentration of sulfur ions is determined by: the time is 5 s-60 min.
11. The method for detecting a sulfide ion concentration according to claim 1, comprising: the auxiliary electrode is one of a platinum electrode or a graphite electrode;
the reference electrode is one of a saturated calomel electrode or a silver chloride electrode;
the external bias voltage value is 0V-1.2V vs.
12. The method for detecting a sulfide ion concentration according to claim 1, comprising: the light source is one of sunlight, xenon lamp, halogen tungsten lamp, metal halogen lamp, incandescent lamp, fluorescent lamp, LED lamp, mercury lamp and laser.
13. The method for detecting a sulfide ion concentration according to claim 12, comprising: the power of the light source is 1mW/cm2～3000mW/cm2。
14. The method for detecting a sulfide ion concentration according to claim 12, comprising: the standard curve of the photoelectrochemistry detection is a linear fitting curve of the photoresponse current and the concentration of the sulfur ions or the concentration logarithm value of the sulfur ions, or a linear fitting curve of the change value of the photoresponse current and the concentration of the sulfur ions or the concentration logarithm value of the sulfur ions.
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