A method for preparing a probe for detecting hydrazine in wastewater

Abstract

This invention discloses a method for preparing a hydrazine probe for detecting hydrazine in wastewater, relating to the field of wastewater detection technology. The method includes thoroughly mixing 2.0 g of 2,4-dihydroxybenzaldehyde and 3.0 g of 2-naphthaleneacetic acid in 20 mL of acetic anhydride, and slowly adding 2 mL of triethylamine. Under nitrogen protection, the mixture is heated under reflux for 8 hours, cooled to room temperature, and a pale yellow solid precipitates. After filtration, a crude product is obtained, which is then recrystallized in ethanol to obtain 3.75 g of a pale yellow solid. The TTAM probe is accurately weighed and diluted with dimethyl sulfoxide (DMSO) to prepare a probe stock solution with a concentration of 1.0 mmol / L. For testing, 20 μL of the stock solution is transferred and diluted to 2 mL with DMSO solution (V(DMSO):V(H2O) = 2:8). An appropriate amount of N2H4 is accurately drawn using a microsyringe and diluted with distilled water to a detection solution of 1.0 mmol / L. Furthermore, at ℇ = 350 M... ‑1 ·cm ‑1 The absorbance at 333 nm ultraviolet absorption is detected. The probe of this invention has high sensitivity, good selectivity, and short response time. The color of the solution changes significantly before and after reacting with N2H4, enabling "naked-eye detection" of N2H4.

Description

Technical Field

[0001] This invention relates to the technical field of wastewater detection, and in particular to a method for preparing a hydrazine probe for detecting hydrazine in wastewater. Background Technology

[0002] Hydrazine hydrate (N₂H₄), also known as hydrazine hydrate, is a crucial chemical raw material in industrial production, used in numerous fields, but most importantly as a propellant for rockets and missiles. Hydrazine is colorless, flammable, and highly toxic; it is easily absorbed by the human body through oral ingestion and skin contact, severely damaging various organs and the nervous system. Various countries have imposed strict limits on its concentration in drinking water. Therefore, developing a highly sensitive and reliable method, especially for detecting low concentrations of N₂H₄, is of paramount importance.

[0003] Currently, there are various methods for detecting N2H4. Organic small molecule fluorescent probe methods are favored by researchers due to their high sensitivity, good selectivity, non-invasiveness, and high spatiotemporal resolution. Therefore, in recent years, researchers have developed many fluorescent probes for N2H4 detection. However, most reported N2H4 fluorescent probes generally suffer from poor selectivity, low sensitivity, complex synthesis, and susceptibility to aggregation quenching, making them difficult to apply in practice. Therefore, this application proposes a method for preparing a hydrazine probe for detecting hydrazine in wastewater to solve the above-mentioned technical problems. Summary of the Invention

[0004] To address the issues of poor selectivity, low sensitivity, complex synthesis, and susceptibility to aggregation quenching that are common in most reported N2H4 fluorescent probes, this invention provides a method for preparing a hydrazine probe for detecting wastewater.

[0005] This invention provides a method for preparing a hydrazine probe for detecting hydrazine in wastewater, employing the following technical solution:

[0006] A method for preparing a probe for detecting hydrazine in wastewater, comprising:

[0007] Mix 2.0 g of 2,4-dihydroxybenzaldehyde and 3.0 g of 2-naphthaleneacetic acid thoroughly in 20 mL of acetic anhydride, and slowly add 2 mL of triethylamine dropwise.

[0008] Under nitrogen protection, the mixture was heated under reflux for 8 hours and cooled to room temperature. A pale yellow solid precipitated out. After filtration, a crude product was obtained. After recrystallization in ethanol, 3.75 g of a pale yellow solid was obtained.

[0009] Accurately weigh the TTAM probe and dilute it with dimethyl sulfoxide (DMSO) to prepare a probe stock solution with a concentration of 1.0 mmol / L. For testing, transfer 20 μL of the stock solution and make up to 2 mL with DMSO solution (V(DMSO)∶V(H2O)=2∶8).

[0010] Accurately extract an appropriate amount of N2H4 using a microsyringe and dilute it with distilled water to a concentration of 1.0 mmol / L in the detection solution. And at ℇ=350M -1 ·cm -1 The absorbance at 333 nm ultraviolet absorption was detected.

[0011] An appropriate amount of sodium salt was directly dissolved in deionized water to prepare F. − Cl − ,Br − S2 − SO3 2− HSO3 − SO4 2− S2O3 2− HCO3 − CO3 2− Ac − Prepare an anion detection solution using a 20µM stock solution of hydrazine hydrate.

[0012] The metal ions added were Pd in ​​that order. 2+ Zn 2+ Mg 2+ Fe 3+ Cu 2+ Na + K + Ca 2+ Al 3+ Ni 2+ Dissolve hydrazine in deionized water to prepare a cation detection solution.

[0013] The added interfering small molecules, namely NH2(CH2)2NH2, CH3(CH2)3NH2, NH2OH, NH3, CO(NH2)2 and hydrated hydrazine, were dissolved in deionized water to prepare the interfering detection solution.

[0014] All ions and interfering small molecules were prepared to a concentration of 400 μM.

[0015] During testing, 0, 10, 20, 30, 40, 50, 60, 70, and 80 μM detection solutions were added to the probe solution sequentially, and all UV analysis data and fluorescence spectrum data of the probe TTAM were recorded after 120 s.

[0016] In summary, this invention offers at least one of the following advantages: using coumarin derivatives as the research object, this compound is prepared through a one-step reaction with appropriate modification. This compound can rapidly and effectively identify N2H4. During the experiment, it exhibits numerous advantages such as high sensitivity, good selectivity, and short response time. The solution color changes significantly before and after the probe reacts with N2H4, enabling "naked-eye detection" of N2H4. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the synthesis route of the probe TTAM of the present invention;

[0018] Figure 2 This is a schematic diagram of the infrared spectrum of the probe TTAM of this invention;

[0019] Figure 3 This is a schematic diagram of the time response of the probe TTAM of the present invention interacting with N2H4;

[0020] Figure 4 This is a schematic diagram of the ultraviolet spectrum of the interaction between the probe TTAM of this invention and hydrated hydrazine;

[0021] Figure 5 This is a schematic diagram of the fluorescence spectrum of the interaction between the probe TTAM of this invention and hydrated hydrazine;

[0022] Figure 6 This is a schematic diagram showing the linear relationship between the fluorescence intensity of the probe TTAM of this invention and the concentration of N2H4.

[0023] Figure 7 This is a schematic diagram of the fluorescence spectrum structure of the probe TTAM of the present invention interacting with cations and N2H4;

[0024] Figure 8 This is a schematic diagram of the fluorescence spectrum of the interaction between the probe TTAM of this invention and anions and N2H4;

[0025] Figure 9 This is a schematic diagram of the fluorescence spectrum of the interaction between the probe TTAM of this invention and nitrogen-containing small molecules and N2H4. Detailed Implementation

[0026] The following is combined with Figure 1-9 The present invention will be described in further detail below.

[0027] Example 1, please refer to the accompanying drawings in the instruction manual. Figure 1 and Figure 2A method for preparing a hydrazine probe for detecting hydrazine in wastewater includes: thoroughly mixing 2.0 g of 2,4-dihydroxybenzaldehyde (approximately 14.7 mmol) and 3.0 g of 2-naphthaleneacetic acid (approximately 16.2 mmol) in 20 mL of acetic anhydride, and slowly adding 2 mL of triethylamine dropwise. Under nitrogen protection, the mixture is heated under reflux for 8 hours, cooled to room temperature, and a pale yellow solid precipitates. After filtration, a crude product is obtained, which is then recrystallized from ethanol to obtain 3.75 g of a pale yellow solid.

[0028] Please refer to the attached diagram in the instruction manual. Figure 3 Accurately weigh the TTAM probe and dilute it with dimethyl sulfoxide (DMSO) to prepare a probe stock solution with a concentration of 1.0 mmol / L. For testing, transfer 20 μL of the stock solution and bring the volume to 2 mL with DMSO solution (V(DMSO):V(H2O) = 2:8). Accurately extract an appropriate amount of N2H4 using a microsyringe and dilute it with distilled water to a detection solution with a concentration of 1.0 mmol / L. And at ℇ = 350 M... -1 ·cm -1 The absorbance at 333 nm ultraviolet absorption was detected.

[0029] An appropriate amount of sodium salt was directly dissolved in deionized water to prepare F. − Cl − ,Br − S2 − SO3 2− HSO3 − SO4 2− S2O3 2− HCO3 − CO3 2− Ac − Prepare an anion detection solution using a 20µM stock solution of hydrazine hydrate. Add metal ions in the following order: Pd... 2 + Zn 2+ Mg 2+ Fe 3+ Cu 2+ Na + K + Ca 2+ Al 3+ Ni 2+ The cation detection solution was prepared by dissolving hydrazine hydrate in deionized water. The small interfering molecules added were, in order, NH2(CH2)2NH2, CH3(CH2)3NH2, NH2OH, NH3, and CO(NH2)2, and hydrazine hydrate was dissolved in deionized water to prepare the interfering substance detection solution.

[0030] All ions and interfering small molecules were prepared to a concentration of 400 μM.

[0031] During testing, 0, 10, 20, 30, 40, 50, 60, 70, and 80 μM detection solutions were added to the probe solution sequentially, and all UV analysis data and fluorescence spectrum data of the probe TTAM were recorded after 120 s.

[0032] Please refer to the attached diagram in the instruction manual. Figure 4-6 Through multiple experiments, the optimal pH for testing was determined to be 8. When 20 µM N2H4 was added to TTAM, the reaction could occur completely and reach equilibrium within 120 s. Therefore, all subsequent fluorescence tests were conducted and recorded after 120 s.

[0033] Please refer to the attached diagram in the instruction manual. Figure 3 After 120 seconds, the fluorescence intensity of the N2H4 probe reached its maximum and remained relatively stable.

[0034] Please refer to the attached diagram in the instruction manual. Figure 3 Considering the influence of solvent toxicity, the DMSO / H2O (v / v, 2 / 8) system of TTAM was used as the solvent for the following experiments.

[0035] Please refer to the attached diagram in the instruction manual. Figure 4 The UV-Vis spectra of the main probe solution with different N2H4 solutions were obtained. The spectra show that the main probe has the maximum absorption at 333 nm. With the addition of different N2H4 concentrations, the absorption value at 333 nm decreases significantly. A new absorption peak appears at 406 nm, which increases with the increase of N2H4 concentration. At the same time, the solution color gradually changes from colorless to yellow-green.

[0036] Please refer to the attached diagram in the instruction manual. Figure 5 The fluorescence spectra of N₂H₄ at different concentrations added to the probe solution are shown. The probe concentration used in the experiment was 10 μM, and the excitation wavelength was 333 nm. The graph shows a maximum emission peak at 480 nm, with the emission peak intensity gradually increasing with the addition of hydrazine hydrate. Under UV light at an excitation wavelength of 365 nm, the fluorescence color changed from light green to blue-green. The presence or absence of N₂H₄ can be determined visually based on this color change.

[0037] Please refer to the attached diagram in the instruction manual. Figure 6 To further investigate the effect of the probe on N2H4, the probe TTAM was treated with different concentrations of N2H4, and the fluorescence response of the probe TTAM to different concentrations of N2H4 was studied. Furthermore, a graph of fluorescence intensity as a function of N2H4 concentration was plotted at 333 nm.

[0038] Please refer to the attached diagram in the instruction manual. Figure 6When the concentration of N2H4 is between 0-40 μM, the fluorescence intensity of the probe shows a good linear relationship with the concentration of N2H4. Data fitting yields the linear regression equation y = 264.8 + 14.08x (linear correlation coefficient R0). 2 =0.977), according to the general instrument minimum detection concentration calculation formula C m =3 σ bi / m, and the detection limit was calculated to be 0.53 μM. These results indicate that TTAM has very high sensitivity.

[0039] To further investigate the selectivity of the probe for N2H4 recognition, fluorescence emission spectroscopy analysis of the added related ions was required. Therefore, under the same testing conditions, the selective responses of TTAM to various anions, cations, and interfering small molecules were accurately studied.

[0040] Please refer to the attached diagram in the instruction manual. Figure 7 The fluorescence spectra of the probe TTAM after interaction with different metal cations and N2H4 are shown in the figure. It can be seen from the figure that the cations have virtually no effect on the probe, exhibiting almost no fluorescence effect. However, the addition of N2H4 significantly enhances the fluorescence intensity, increasing it by more than 10 times, which is sufficient to demonstrate that the aforementioned cations do not interfere with the detection of hydrated hydrazine.

[0041] Please refer to the attached diagram in the instruction manual. Figure 8 The fluorescence selectivity of the probe to different anions shows that the effect of anions on the probe is similar to that of cations, with virtually no fluorescence effect. Only the addition of N2H4 results in a significant enhancement of fluorescence intensity.

[0042] Please refer to the attached diagram in the instruction manual. Figure 9 The fluorescence selectivity diagrams of different nitrogen-containing interfering small molecules show that when only hydroxylamine hydrochloride is added, it has a slight interaction with the probe body but does not affect the detection of hydrated hydrazine. The effect on other interfering small molecules is even smaller, which is enough to prove that the probe exhibits good anti-interference ability.

[0043] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a probe for detecting hydrazine in wastewater, characterized in that: include, S1: Mix 2.0g of 2,4-dihydroxybenzaldehyde and 3.0g of 2-naphthaleneacetic acid thoroughly in 20mL of acetic anhydride, and slowly add 2mL of triethylamine. S2: In step S1, under the protection of a chemically inert gas, the mixture is heated under reflux for several hours and cooled to room temperature. A pale yellow solid precipitates out. After filtration, a crude product is obtained. After recrystallization in an organic solvent, 3.75 g of a pale yellow solid is obtained, thus preparing 3-(2-naphthyl)-7-acetoxycoumarin (TTAM). S3: Accurately weigh the TTAM probe and dilute it with dimethyl sulfoxide (DMSO) to prepare the probe stock solution; S4: Transfer 20 μL of the stock solution and bring the volume to 2 mL with DMSO solution; S5: Accurately extract an appropriate amount of N2H4 using a microsyringe and dilute it with distilled water to a concentration of 1.0 mmol / L in the detection solution, and at ℇ=350M -1 cm -1 The absorbance at 333 nm ultraviolet absorption was measured. S6: Dissolve an appropriate amount of sodium salt directly in deionized water to prepare various selective detection solutions; S7: The volume of each selective detection solution is 400 μM; S8: During the test, 0, 10, 20, 30, 40, 50, 60, 70, and 80 μM detection solutions were added to the probe solution in sequence, and all UV analysis data and fluorescence spectrum data of the probe TTAM were recorded after 120 seconds.

2. The method for preparing a hydrazine probe for detecting hydrazine in wastewater according to claim 1, characterized in that: The chemically inert gas is nitrogen.

3. The method for preparing a hydrazine probe for detecting hydrazine in wastewater according to claim 1, characterized in that: The organic solvent is liquid ethanol.

4. The method for preparing a hydrazine probe for detecting hydrazine in wastewater according to claim 1, characterized in that: The concentration of the probe stock solution was 1.0 mmol / L.

5. The method for preparing a hydrazine probe for detecting hydrazine in wastewater according to claim 1, characterized in that: The volume ratio of the DMSO solution is V(DMSO):V(H2O) = 2:

8.

6. The method for preparing a hydrazine probe for detecting hydrazine in wastewater according to claim 1, characterized in that: When preparing the selective detection solution, prepare F − Cl − ,Br − S2 − SO3 2− HSO3 − SO4 2− S2O3 2− 、HCO3 − CO3 2− Ac − Prepare an anion detection solution using a 20µM stock solution of hydrazine hydrate.

7. The method for preparing a hydrazine probe for detecting hydrazine in wastewater according to claim 1, characterized in that: In preparing the selective detection solution, pd is added sequentially. 2+ Zn 2+ Mg 2+ Fe 3+ Cu 2+ Na + K + Ca 2+ Al 3+ Ni 2+ Dissolve hydrazine in deionized water to prepare a cation detection solution.

8. The method for preparing a hydrazine probe for detecting hydrazine in wastewater according to claim 1, characterized in that: In preparing the selective detection solution, NH2(CH2)2NH2, CH3(CH2)3NH2, NH2OH, NH3, CO(NH2)2 and hydrated hydrazine are dissolved in deionized water in sequence to prepare the interference detection solution.

9. The method for preparing a hydrazine probe for detecting hydrazine in wastewater according to claim 1, characterized in that: During testing, the pH value was controlled at 8.

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