CN110161009A - Tin dioxide quantal-point detects the application and detection method of heavy metal ions in sewage - Google Patents

Abstract

The invention discloses an application and a detection method of tin dioxide quantum dots for detecting heavy metal ions in sewage. The tin dioxide quantum dots have the advantages of non-toxicity, good chemical stability, low cost, wide excitation spectrum and narrow emission spectrum, and are used as It is used as a fluorescent probe for detecting heavy metal ions in sewage. The present invention also provides a method for detecting heavy metal ions in sewage by tin dioxide quantum dots. Firstly, a quantitative standard curve is established to detect the change in fluorescence intensity of each heavy metal ion and the concentration of each heavy metal. The more data in the standard library, the more accurate the detection The higher the sensitivity, then mix the tin dioxide quantum dot standard solution and the solution to be tested at room temperature, measure and calculate the fluorescence intensity change of the tin dioxide quantum dot standard solution before and after the reaction, and use the quantitative standard curve to find the corresponding fluorescence intensity change. The concentration of heavy metal ions is enough, the tin dioxide quantum dot of the present invention has high sensitivity, and after having a standard library, it is easy to detect and has wide application prospects.

Description

Application and detection method of tin dioxide quantum dots to detect heavy metal ions in sewage

technical field

The invention relates to the technical field of fluorescent materials, and more specifically relates to an application and a detection method of tin dioxide quantum dots for detecting heavy metal ions in sewage.

Background technique

Pollution has become a serious concern all over the world, heavy metals discharged from industrial wastewater may come from metal plating equipment, metal surface treatment, chemical, fertilizer and cardboard factory production. These heavy metal ions pose a major threat to the environment and public health due to their non-biodegradability and strong toxicity to plants, animals, and humans. Therefore, it is urgent to develop a simple and sensitive method for the detection of heavy metal ions in water.

Quantum dots are an important low-dimensional semiconductor material, whose size in three dimensions is not larger than twice the exciton Bohr radius of the corresponding semiconductor material. Quantum dots are generally spherical or quasi-spherical, and their diameters are usually between 2-20nm. Common quantum dots are composed of IV, II-VI, IV-VI or III-V elements. Quantum dots are nano-scale semiconductors. By applying a certain electric field or light pressure to this nano-semiconductor material, they will emit fluorescence at a specific frequency.

There are already some techniques for detecting heavy metal ions, such as atomic absorption spectroscopy, inductively coupled plasma mass spectrometry, and fluorescence spectroscopy. However, these methods have high requirements for operators, and the detection cost is high and the processing process is complicated. Quantum dots are semiconductor nanocrystal particles with wide excitation spectrum and narrow emission spectrum, strong chemical stability and photostability, and long fluorescence lifetime. These characteristics make quantum dots receive more and more attention. Quantum dots As a fluorescent probe, it has become a hotspot in the field of analytical chemistry, including the detection of heavy metal ions in water.

Several kinds of quantum dots have been successfully synthesized, such as CdS, CdTe, ZnS quantum dots and their composites. However, some of them contain toxic elements.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art, and to provide an application and a detection method for tin dioxide quantum dots to detect heavy metal ions in sewage. Tin dioxide (SnO ₂ ) quantum dots are an environmentally friendly semiconductor with It has the advantages of high toxicity, good chemical stability and low cost.

To achieve the above object, the technical scheme of the present invention is as follows:

The application of tin dioxide quantum dots to detect heavy metal ions in sewage. The specific heavy metals that can be detected are copper, lead, zinc, tin, nickel, cobalt, antimony, mercury, cadmium or bismuth. The particle size of tin dioxide quantum dots is preferably 2nm ~10nm.

The present invention also provides a method for detecting heavy metal ions in sewage by tin dioxide quantum dots, which is characterized in that it comprises the following steps:

Step S1: prepare a certain concentration of tin dioxide quantum dot standard solution, and measure its fluorescence intensity;

Step S2: Prepare heavy metal ion solutions of different concentrations, add them to the tin dioxide quantum dot standard solution prepared in step S1 respectively, measure the fluorescence intensity of each solution after the reaction, and draw the fluorescence intensity before and after the addition of the heavy metal ion solution vs. Quantitative standard curve between heavy metal ion concentrations;

Step S3: Add the liquid to be detected to the tin dioxide quantum dot standard solution prepared in step S1, measure the fluorescence intensity after the reaction, calculate the change in fluorescence intensity before and after the addition of the liquid to be detected, and obtain a quantitative standard curve in step S2 , find the concentration of heavy metal ions corresponding to the change in fluorescence intensity.

Preferably, the heavy metal is copper, lead, zinc, tin, nickel, cobalt, antimony, mercury, cadmium or bismuth.

Preferably, in the step S1, the method for preparing the tin dioxide quantum dot standard solution is: dissolving a certain amount of stannous chloride and thiourea in deionized water, and stirring magnetically at room temperature to obtain the tin dioxide quantum dot solution.

Preferably, the weight ratio of stannous chloride and thiourea is 20-50:1.

Preferably, fluorescence intensity is measured using a spectrofluorometer.

Preferably, in the step S1, the concentration of the tin dioxide quantum dot standard solution is 1E-6mol/L˜1E-1mol/L.

Preferably, the particle size of the tin dioxide quantum dots in the tin dioxide quantum dot standard solution is 2 nm to 10 nm.

It can be seen from the above technical scheme that tin dioxide quantum dots have the advantages of non-toxicity, good chemical stability, low cost, wide excitation spectrum and narrow emission spectrum, and are used as fluorescent probes for detecting heavy metal ions in sewage. The present invention also provides a method for tin dioxide quantum dots to detect heavy metal ions in sewage. First, establish a quantitative standard curve between the variation of fluorescence intensity of each heavy metal ion and the concentration of each heavy metal. The more data in the standard library, the better. The higher the accuracy, then mix the tin dioxide quantum dot standard solution and the solution to be detected at room temperature, measure and calculate the fluorescence intensity change of the tin dioxide quantum dot standard solution before and after the reaction, and use the quantitative standard curve to find the fluorescence intensity change The concentration of heavy metal ions corresponding to the amount is enough. The tin dioxide quantum dots of the present invention have high sensitivity, and after having a standard library, the detection is simple and has wide application prospects.

Description of drawings

Fig. 1 is the _SnO that the present invention prepares The particle size distribution figure of quantum dot, among the figure, abscissa represents particle diameter, and the left side vertical coordinate represents the quantum dot of each particle diameter to account for the percentage of all quantum dots, and the right vertical coordinate represents all quantum dots The percentage of the quantum dot sum of all particle sizes before the particle size corresponding to the abscissa to all quantum dots;

Fig. ₂ is the SnO prepared by the present invention observed with a high-resolution transmission electron microscope (TEM) The morphology of quantum dots;

Fig. 3 is the XRD pattern of the _SnO powder obtained from the aqueous solution containing _SnO quantum dots in the present invention;

Fig. 4 is the fluorescence intensity after being excited by the light of 310nm wavelength in different concentration tin dioxide solution among the present invention;

Fig. 5 is a fluorescence spectrum diagram after mixing SnO ₂ quantum dots and heavy metal ions in the present invention, wherein the peak appears at the emission wavelength of 300nm to 310nm.

Detailed ways

The specific embodiment of the present invention will be further described in detail below in conjunction with the accompanying drawings.

It should be noted that, in the following specific embodiments, when describing the embodiments of the present invention in detail, in order to clearly show the structure of the present invention for the convenience of description, the structures in the drawings are not drawn according to the general scale, and are drawn Partial magnification, deformation and simplification are included, therefore, it should be avoided to be interpreted as a limitation of the present invention.

The synthesis method of tin dioxide quantum dots, a certain amount of tin protochloride (SnCl ₂ 2H ₂ O) and thiourea (CH ₄ N ₂ S) are dissolved in deionized water, magnetically stirred at room temperature to obtain tin dioxide quantum dots solution. Stannous chloride provides the tin source, and thiourea serves as the catalyst and stabilizer.

In this example, weigh 2.257g of stannous oxide (SnCl ₂ ·2H ₂ O) and 0.077g of thiourea (CH ₄ N ₂ S), dissolve them in 50ml of deionized water, and place them in a magnetic stirring device at about 25°C Stir in a water bath for 24h. After hydrolytic oxidation of _SnCl2 , an aqueous _SnO2 quantum dot solution was obtained. Wherein the concentration of the finally obtained tin dioxide quantum dot solution is 0.2 mol/l.

The particle size of SnO ₂ quantum dots was analyzed by dynamic light scattering. As shown in Figure 1, the particle size ranges from 2nm to 10nm, and the average particle size is 2.23nm. It can be seen that the prepared quantum dots have uniform dispersion in aqueous solution.

The solution was dried into a powder, and its morphology was observed with a transmission electron microscope, referring to Figure 2. It had a regular rutile appearance, and X-ray diffraction was performed, as shown in Figure 3.

The method for detecting heavy metal ions in polluted water with the tin dioxide quantum dot prepared above comprises the following steps:

S1: Prepare a standard solution of tin dioxide quantum dots at a certain concentration, and measure its fluorescence intensity with a fluorescence spectrophotometer.

In order to find the tin dioxide quantum dot solution concentration of optimum sensitivity, prepare tin dioxide quantum dot solutions of different concentrations, utilize a fluorescence spectrophotometer to measure fluorescence intensity, as shown in Figure 4, preferably, tin dioxide quantum dot standard solution The concentration is 1E-6mol/L～1E-1mol/L.

In this embodiment, the concentration of the tin dioxide quantum dot solution with the strongest fluorescence is taken as the concentration of the standard solution, that is, 1E-4.

S2: Make standard library data and prepare heavy metal ion solutions with different concentrations. The heavy metals can be copper, lead, zinc, tin, nickel, cobalt, antimony, mercury, cadmium or bismuth, respectively added to the tin dioxide quantum dots prepared in step S1 In the standard solution, measure the fluorescence intensity of each solution after the reaction, and draw a quantitative standard curve between the change of the fluorescence intensity before and after the addition of the heavy metal ion solution and the concentration of the heavy metal ion. The more data in the standard library, the closer the fitted quantitative standard curve is to the real one, and the more accurate the detection result.

See Figure 5, taking Cu ²⁺ , Pd ²⁺ , Cd ²⁺ , Ni ²⁺ and Fe ³⁺ as examples, the fluorescence spectrum of SnO ₂ quantum dots mixed with heavy metal ions, in which the peak appears at the emission of 300nm to 310nm wavelength. It can be seen that tin dioxide quantum dots have good fluorescence response to heavy metal ^ions such as Cu ²⁺ , Pd ²⁺ , Cd ²⁺ , Ni ²⁺ and Fe ³⁺ , with short response time and low detection limit.

S3: Add the liquid to be detected to the tin dioxide quantum dot standard solution prepared in step S1, measure the fluorescence intensity after the reaction, calculate the change in fluorescence intensity before and after the addition of the liquid to be detected, in the quantitative standard curve prepared in step S2 , to find the concentration of heavy metal ions corresponding to the change in fluorescence intensity. Heavy metal ions will lead to the weakening of the fluorescence intensity of quantum dots.

In this embodiment, the variation of the fluorescence intensity is equal to the fluorescence intensity value measured after the reaction divided by the fluorescence intensity value measured before the reaction.

The method for detecting heavy metal ions by tin dioxide quantum dots has high sensitivity, the detection process is simple, fast, and does not require complicated pretreatment. These characteristics make this reagent a promising reagent for detecting heavy metal ions in water.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concepts thereof shall fall within the protection scope of the present invention.

Claims (10)

1. The application of tin dioxide quantum dots to detect heavy metal ions in sewage. 2. The application according to claim 1, characterized in that the heavy metal is copper, lead, zinc, tin, nickel, cobalt, antimony, mercury, cadmium or bismuth. 3. The application according to claim 1, characterized in that the particle size of the tin dioxide quantum dots is 2 nm to 10 nm. 4. A method for tin dioxide quantum dots to detect heavy metal ions in sewage, is characterized in that, comprises the following steps: Step S1: prepare a certain concentration of tin dioxide quantum dot standard solution, and measure its fluorescence intensity; Step S2: Prepare heavy metal ion solutions of different concentrations, add them to the tin dioxide quantum dot standard solution prepared in step S1 respectively, measure the fluorescence intensity of each solution after the reaction, and draw the fluorescence intensity before and after the addition of the heavy metal ion solution vs. Quantitative standard curve between heavy metal ion concentrations; Step S3: Add the liquid to be detected to the tin dioxide quantum dot standard solution prepared in step S1, measure the fluorescence intensity after the reaction, calculate the change in fluorescence intensity before and after the addition of the liquid to be detected, and obtain a quantitative standard curve in step S2 , find the concentration of heavy metal ions corresponding to the change in fluorescence intensity. 5. The method according to claim 4, wherein the heavy metal is copper, lead, zinc, tin, nickel, cobalt, antimony, mercury, cadmium or bismuth. 6. method according to claim 4, is characterized in that, in described step S1, the method for preparing tin dioxide quantum dot standard solution is: a certain amount of stannous chloride and thiourea are dissolved in deionized water, Magnetic stirring at room temperature to obtain a tin dioxide quantum dot solution. 7. The method according to claim 6, characterized in that the ratio of parts by weight of stannous chloride and thiourea is 20 to 50:1. 8. The method according to claim 4, characterized in that a fluorescence spectrophotometer is used to measure the fluorescence intensity. 9. The method according to claim 4, characterized in that, in the step S1, the concentration of the tin dioxide quantum dot standard solution is 1E-6mol/L˜1E-1mol/L. 10. The method according to claim 4, characterized in that, the particle size of the tin dioxide quantum dots in the tin dioxide quantum dot standard solution is 2 nm to 10 nm.