Synthesis method of fluorescent nano sensor for monitoring content of ferric ions in sewage

Abstract

The invention relates to the technical field of fluorescent nano sensors, in particular to a synthesis method of a fluorescent nano sensor for monitoring the content of ferric ions in sewage. The method comprises the following steps: 1, carrying out anhydrous and anaerobic treatment on a reactor, cooling to room temperature, adding an F127 or P123 solution into the reactor, and adding 10-ethyl-3, 7-diformaldehyde phenothiazine under a stirring condition to synthesize fluorescein isothiocyanate with the concentration of (1-9) * 10 <-4 > mol / L; and 2, adding ethanol into fluorescein isothiocyanate, fully stirring, adding tetraethoxysilane, reacting, adding a terminator, continuously stirring, filtering by using a water-based filter membrane, and dialyzing by using deionized water until particles are neutral, thereby obtaining the fluorescent nano sensor. The size of the synthesized fluorescent nano sensor is lower than 20 nm, the water compatibility is good, the luminous intensity in water is high, the online detection capability is achieved, the detection method is visual and effective, and the method can be suitable for chemical sewage and domestic sewage.

Description

Technical fields:

[0001] This invention relates to the field of fluorescent nanosensor technology, and in particular to a method for synthesizing a fluorescent nanosensor for monitoring the content of ferric ions in wastewater. Background technology:

[0002] Ferric ions (Fe3+) are a prevalent inorganic pollutant in wastewater, particularly in wastewater from chemical refining processes. Excessive Fe3+ discharge not only pollutes rivers and affects drinking water quality but also easily causes disease in river animals and plants, leading to serious ecological and environmental problems. Therefore, monitoring Fe3+ in wastewater is crucial. Currently, the primary method for Fe3+ monitoring is inductively coupled plasma (ICP) spectroscopy. While this technology offers high precision and accurate measurements, its inability to perform real-time online monitoring makes it unsuitable for rapid wastewater source tracing. Fluorescence monitoring, as a direct and effective method, allows for real-time online monitoring without damaging the water sample. It directly characterizes the presence of Fe3+ through spectral color and luminescence, making it an effective analytical approach. The design of the fluorescence sensor is critical in fluorescence monitoring. When designing a wastewater fluorescence sensor, it is essential to ensure that the sensor is homogeneously dispersed in the water, does not react with other substances in the water, has good water compatibility, and exhibits excellent luminescence performance in water.

[0003] However, the reported water-based nanofluorescent sensors have at least the following problems:

[0004] Chinese patent CN106190098A utilizes inorganic phosphors as suspensions, resulting in long fluorescence lifetimes, but its dispersibility is poor. Chinese patent CN103342698A employs purely organic fluorescent sensing materials to monitor metal ions, but its poor water solubility prevents its use in aqueous systems. Chinese patent CN106085410A utilizes a PEI and fluorescein complex to prepare fluorescent nanoprobes with good water solubility; however, its ability to monitor ferric ions is poor, and it only responds to copper ions. Summary of the Invention:

[0005] The technical problem to be solved by the present invention is to provide a method for synthesizing a fluorescent nanosensor for monitoring the content of ferric ions in wastewater. The method realizes the synthesis of a fluorescent nanosensor with a size of less than 20 nm, good water compatibility, and high luminescence intensity in water by using tetraethyl orthosilicate and nonionic surfactant triblock copolymer through soft template method. The monitoring sensor has the ability to detect online, the detection method is intuitive and effective, it can be applied to chemical wastewater and domestic sewage, and it can also resist the interference of organic pollutants and other metal ions.

[0006] The technical solution adopted in this invention is: a method for synthesizing a fluorescent nanosensor for monitoring the content of ferric ions in wastewater, the steps of which are as follows:

[0007] Step 1: The reactor is subjected to anhydrous and oxygen-free treatment and cooled to room temperature. F127 or P123 solution is added to the reactor, and under stirring, 10-ethyl-3,7-dicarboxaldehyde phenthiazide is added to synthesize fluorescein isothiocyanate at a concentration of 1–9 × 10⁻⁶. -4 mol / L;

[0008] Step 2: Add ethanol to fluorescein isothiocyanate, stir thoroughly, then add tetraethyl orthosilicate. After the reaction, add a terminator and continue stirring. Filter with an aqueous filter membrane and then dialyze with deionized water until the particles are neutral, which is the fluorescent nanosensor.

[0009] Further, in step two, ethanol is added to fluorescein isothiocyanate, and after stirring thoroughly for 1 hour, tetraethyl orthosilicate is added. After reacting for 0.5 to 2 hours, a terminator is added and stirring is continued for 2 to 48 hours. The mixture is then filtered through an aqueous filter membrane and dialyzed with deionized water for 24 hours until the particles are neutral, which is the fluorescent nanosensor.

[0010] Furthermore, the F127 solution is an aqueous or hydrochloric acid solution prepared with F127, and the amount of F127 added is 30-50g / 500mL.

[0011] Furthermore, the P123 solution is a water or hydrochloric acid solution prepared from P123, and the amount of P123 added is 50-80g / 500mL.

[0012] Furthermore, the concentration of the hydrochloric acid is between 0 and 1 mol / L.

[0013] Further, the amount of 10-ethyl-3,7-dicarboxaldehyde phenthiazide added is 1×10 -4 g / mL~9×10 -4 A solution of F127 or P123 at a concentration of g / mL.

[0014] Furthermore, the volume ratio of the F127 or P123 solution to tetraethyl orthosilicate is 20:1 to 10:1.

[0015] Furthermore, the terminating agent is one or two of dichlorodimethylsilane, dichlorodiethoxysilane, and PEG-substituted silane.

[0016] Furthermore, the amount of the terminator added is 20-80 μL / 50 mL of LF127 or P123 solution, and 80 μL is added to a 20 mL reaction system when using the terminator.

[0017] Furthermore, the pH of this synthesis system is between 2 and 7.

[0018] Furthermore, the water-based filter membrane is of 0.22μm or 0.45μm, and the filter head is used for filtration with a syringe.

[0019] Furthermore, the preferred size of the aqueous filter membrane is 0.22 μm.

[0020] Furthermore, the stirring speed in steps one and two is 300–500 r / min.

[0021] The beneficial effects of this invention are:

[0022] This invention utilizes a soft template method to synthesize a fluorescent nanosensor with a size of less than 20 nm, good water compatibility, and high luminescence intensity in water using tetraethyl orthosilicate and nonionic surfactant triblock copolymer. This monitoring sensor has online detection capability, and the detection method is intuitive and effective. It can be applied to chemical wastewater and domestic sewage, and can also resist interference from organic pollutants and other metal ions. Detailed implementation method:

[0023] The preferred embodiments of the present invention will be described in more detail below to further illustrate the present invention, but this does not constitute a limitation on the scope of protection of the present invention.

[0024] This invention uses high-resolution transmission electron microscopy (HR-TEM) to determine the size of particles.

[0025] This invention uses DLS dynamic light scattering to determine the monodispersity of particles.

[0026] This invention uses steady-state fluorescence spectroscopy to determine the luminescence intensity of the nanosensor and the effect of iron ions on the fluorescence intensity of the nanosensor.

[0027] This invention uses three-dimensional fluorescent fingerprint changes to determine the factors that cause sensor quenching due to iron ions.

[0028] Example 1

[0029] The synthesis method used in all embodiments of this invention is the soft template method, and the reactor used is a 20mL sealed glass reaction flask. The specific polymerization operation is as follows:

[0030] The reaction system consisted of 20 mL of a sealed glass bottle with a gasket inside. The bottle was anhydrous and oxygen-free, and cooled to room temperature. The soft template was F127. 30 g of F127 was used to prepare a 500 mL hydrochloric acid solution with a concentration of 1 mol / L. 10 mL of the F127 solution was added to the reaction bottle. While stirring at 300 rpm, a solution of F127 or P123 containing 1 × 10⁻⁶ ethyl-3,7-dicarboxaldehyde phenothiazine was added, with a concentration of 1 × 10⁻⁶. -4g / mL, added in a volume of 0.02 mL. Synthesize fluorescein isothiocyanate at a concentration of 9 × 10⁻⁶ g / mL. -4 While stirring, 100 μL of ethanol solution was added to the solution at a concentration of mol / L. After stirring thoroughly for 1 hour, 1 mL of tetraethyl orthosilicate was added, wherein the volume ratio of tetraethyl orthosilicate to F127 solution was 1:10. After reacting for 2 hours, 80 μL of terminator was added, and stirring was continued for 48 hours. Then, the solution was filtered through a 0.22 μm aqueous filter membrane and dialyzed with deionized water for 24 hours, dialyzing every 0.5 hours with 1000 mL of deionized water each time, until the pH test paper showed neutrality after 24 hours. This is the fluorescent nanosensor. The filter head of the aqueous filter membrane was filtered using a syringe. The pH of the synthesis system in this embodiment was 2.

[0031] The fabricated fluorescent nanosensor has a water particle force radius of 18 nm and is used to detect ferric ions using fluorescence titration. 3+ The detection limit is 0.05 ppm. The monodispersity of the particles is PDI value of 0.1. The luminescence intensity of the nanosensor was determined to be 1.5 × 10⁻⁶ using steady-state fluorescence spectroscopy. 6 0.1 ppm of iron ions reduced the fluorescence intensity of the nanosensor by 20%.

[0032] Compared to Comparative Example 1, the detection limit was reduced by 50%.

[0033] Example 2

[0034] The fluorescent sensor was prepared under the same conditions as described in Example 1, except that the soft template was P123, and 50g of P123 was dissolved in 500mL of water.

[0035] The fabricated fluorescent nanosensor has a size smaller than 15 nm and high brightness. The detection limit for ferric ions using fluorescence titration is 0.12 ppm. The monodispersity of the particles is PDI value of 0.5; 0.12 ppm of ferric ions causes a 10% decrease in the fluorescence intensity of the nanosensor.

[0036] Compared to Comparative Example 2, the detection limit was reduced by approximately 40%.

[0037] Example 3

[0038] The fluorescence sensor was prepared under the same conditions as described in Example 1, except that the stirring speed was 400 r / min.

[0039] The fabricated fluorescent nanosensor has a size smaller than 20 nm, and the detection limit for trivalent iron ions using fluorescence titration is 0.08 ppm. The monodispersity of the particles is 0.7 (PDI value), and the luminescence intensity of the nanosensor was determined to be 0.9 × 10⁻⁶ using steady-state fluorescence spectroscopy. 5 0.1 ppm of iron ions reduced the fluorescence intensity of the nanosensor by 7%.

[0040] Compared to Comparative Example 3, the detection limit was reduced by approximately 60%.

[0041] Example 4

[0042] The fluorescence sensor was prepared under the same conditions as described in Example 1, except that a solution of F127 or P123 containing 10-ethyl-3,7-dicarboxaldehyde phenthiazide was added at a concentration of 5 × 10⁻⁶. -4 At a concentration of g / mL, 0.07 mL was added to synthesize fluorescein isothiocyanate, with a concentration of 8 × 10⁻⁶ g / mL. -4 mol / L.

[0043] The fabricated fluorescent nanosensor has a size of less than 20 nm, and the detection limit for detecting ferric ions by fluorescence titration is 0.1 ppm.

[0044] Compared to Comparative Example 4, the detection limit was reduced by 30%.

[0045] Example 5

[0046] The fluorescence sensor was prepared under the same conditions as described in Example 1, except that the concentration of hydrochloric acid was 0.5 mol / L and the pH of the synthesis system in this example was 4.

[0047] The fabricated fluorescent nanosensor has a size of less than 15 nm, and the detection limit for detecting ferric ions by fluorescence titration is 0.14 ppm.

[0048] Compared to Comparative Example 5, the detection limit was reduced by 20%.

[0049] Example 6

[0050] The fluorescence sensor was prepared under the same conditions as described in Example 1, except that the terminator was dichlorodimethylsilane, and the amount added was 80 μL.

[0051] The fabricated fluorescent nanosensor has a size of less than 15 nm, and the detection limit for detecting ferric ions by fluorescence titration is 0.12 ppm.

[0052] Compared to Comparative Example 6, the detection limit was reduced by 15%.

[0053] Comparative Example 1

[0054] The fluorescent sensor was prepared under the same conditions as described in Example 1, except that 22g of F127 was prepared into a 500mL aqueous solution, and 10mL of the F127 solution was added to the reaction flask. The resulting nano-fluorescent sensor had a detection limit of 0.2ppm for iron ions.

[0055] Comparative Example 2

[0056] The fluorescent sensor was prepared under the same conditions as described in Example 1, except that 36g of P123 was prepared into a 500mL aqueous solution, and 10mL of F123 solution was added to the reaction flask. The resulting nano-fluorescent sensor had a detection limit of 0.4ppm for iron ions.

[0057] Comparative Example 3

[0058] The fluorescence sensor was prepared under the same conditions as described in Example 1, except that the stirring speed was 150 r / min, a transparent particle suspension could not be formed, the particle size was greater than 50 nm, and the iron ion detection limit was 1.5 ppm.

[0059] Comparative Example 4

[0060] The fluorescence sensor was prepared under the same conditions as described in Example 1, except that a solution of F127 or P123 containing 10-ethyl-3,7-dicarboxaldehyde phenthiazide was added at a concentration of 9 × 10⁻⁶. -4 A concentration of g / mL was added to 0.02 mL to synthesize fluorescein isothiocyanate, with a concentration of 0.1 × 10⁻⁶ g / mL. -4 The prepared fluorescent nanosensor has a size of less than 20 nm and a detection limit of 15 ppm for detecting ferric ions using fluorescence titration.

[0061] Comparative Example 5

[0062] The fluorescence sensor was prepared under the same conditions as described in Example 1, except that the acidity of the solution was changed by adding sodium carbonate to make the pH 9, which prevented the preparation of silica nanoparticles and resulted in an amorphous structure.

[0063] Comparative Example 6

[0064] The fluorescence sensor was prepared under the same conditions as described in Example 1, except that no terminator was used, resulting in a turbid silica suspension with uneven particle size, some large and some small, which could not be used for iron ion detection and did not produce stable fluorescence emission.

[0065] In summary, as shown in Examples 1-6 and Comparative Examples 1-6, the fluorescent nanosensor synthesized by the present invention has a size of less than 20 nm, good water compatibility, high luminescence intensity in water, and the ability to detect online. The detection method is intuitive and effective, applicable to both chemical wastewater and domestic sewage, and can also resist interference from organic pollutants and other metal ions.

[0066] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A method for synthesizing a fluorescent nanosensor for monitoring the content of ferric ions in wastewater, characterized in that: The steps of this method are as follows: Step 1: The reactor is subjected to anhydrous and oxygen-free treatment and cooled to room temperature. F127 or P123 solution is added to the reactor, and under stirring, 10-ethyl-3,7-dicarboxaldehyde phenthiazide is added to synthesize fluorescein isothiocyanate at a concentration of 1–9 × 10⁻⁶. -4 mol / L; Step 2: Add ethanol to fluorescein isothiocyanate, stir thoroughly, then add tetraethyl orthosilicate. After the reaction, add a terminator and continue stirring. Filter with an aqueous filter membrane and then dialyze with deionized water until the particles are neutral, which is the fluorescent nanosensor.

2. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: In step two, ethanol is added to fluorescein isothiocyanate, and after stirring thoroughly for 1 hour, tetraethyl orthosilicate is added. After reacting for 0.5 to 2 hours, a terminator is added and stirring is continued for 2 to 48 hours. The mixture is then filtered through an aqueous filter membrane and dialyzed with deionized water for 24 hours until the particles are neutral, which yields the fluorescent nanosensor.

3. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: The F127 solution is an aqueous or hydrochloric acid solution prepared with F127, and the amount of F127 added is 30-50g / 500mL.

4. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: The P123 solution is a water or hydrochloric acid solution prepared from P123, and the amount of P123 added is 50-80g / 500mL.

5. The method for synthesizing a fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 3 or 4, characterized in that: The concentration of the hydrochloric acid is between 0 and 1 mol / L.

6. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: The amount of 10-ethyl-3,7-dicarboxyphenthiazide added is 1×10 -4 g / mL~9×10 -4 A solution of F127 or P123 at a concentration of g / mL.

7. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: The volume ratio of the F127 or P123 solution to tetraethyl orthosilicate is 20:1 to 10:

1.

8. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: The terminator is one or two of dichlorodimethylsilane, dichlorodiethoxysilane, and PEG-substituted silane.

9. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: The amount of the terminator added is 20-80 μL / 50 mL of LF127 or P123 solution. When using the terminator, add 80 μL to a 20 mL reaction system.

10. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: The pH of this synthesis system is between 2 and 7.

11. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: The water-based filter membrane is of 0.22μm or 0.45μm, and the filter head is used for filtration with a syringe.

12. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 11, characterized in that: The preferred type of water-based filter membrane is 0.22 μm.

13. The method for synthesizing the fluorescent nanosensor for monitoring the content of ferric ions in wastewater according to claim 1, characterized in that: The stirring speed in steps one and two is 300-500 r / min.