Electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions and its preparation method

Abstract

This invention provides an electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions and its preparation method. A rare-earth fluorescent material emitting strong red light under 365nm ultraviolet light is prepared using ligands and rare-earth compounds. This rare-earth fluorescent material is then added to a spinning solution obtained by hydrophilically modified polymer solution. The electrospun solution is then used to prepare the electrospun fluorescent nanocomposite fiber membrane for detecting copper ions. A linear relationship exists between the copper ion concentration and the fluorescence intensity. This membrane can be applied to rapid detection of copper ions in fields such as environmental analysis and rapid food safety testing.

Description

Technical Field

[0001] This invention relates to the field of nanocomposite functional textile materials, and in particular to an electrospun fluorescent nanocomposite fiber membrane for heavy metal wastewater detection and its preparation method, which can detect copper ions. Background Technology

[0002] Copper ions play an important role in the growth and development of the body, as well as the maturation of the nervous, hematopoietic, skeletal, and other systems. However, excessive Cu... 2+ It can trigger harmful reactions in the human body and hinder healthy development. Due to increasing industrialization and stricter water quality regulations, the levels of Cu in industrial wastewater, domestic drinking water, and even biological blood are becoming increasingly important. 2+ Sensitive monitoring of the presence of copper ions has become an important issue; establishing efficient, rapid, simple and sensitive methods for detecting copper ions is of great significance in human health, environmental monitoring and other aspects.

[0003] To date, various methods for detecting the heavy metal copper ion have been reported. The most widely accepted methods are atomic absorption spectrometry (AAS), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectrometry (ICP-OES), ion-selective membrane electrodes, and voltammetry. Each of these methods can quantitatively measure the content of metal ions in a specific sample. However, these methods are inconvenient to use, requiring expensive and bulky equipment, long testing times, large amounts of sample preparation, and the inability to perform on-site detection. Therefore, optical sensors with colorimetric or fluorescent activity have been developed. These sensors are not only simple and cost-effective but also highly selective and sensitive. However, some small-molecule sensors also present post-detection contamination problems; some liquid detection methods can have environmental impacts when combined with the analyte.

[0004] Therefore, there is an urgent need in the market for a low-cost, low-pollution solution that can quickly detect copper ions in a sample. Summary of the Invention

[0005] The purpose of this solution is to provide an electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions and its preparation method, which can be applied to the rapid detection of copper ions in fields such as environmental analysis and rapid food safety testing.

[0006] To achieve the above, this technical solution provides a method for preparing an electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions, comprising the following steps:

[0007] Preparation of rare earth fluorescent materials: The ligand is dissolved in ethanol to obtain a first solution, and the rare earth compound is dissolved in deionized water to obtain a second solution, wherein the molar ratio of ligand to rare earth ions is 1-5:1. The first and second solutions are mixed and the pH is adjusted to 5-7. The reaction is carried out at 25℃ for 4-8 hours. Deionized water is added to the solution after the reaction to precipitate the material. The mixture is centrifuged twice to obtain a yellow solid as the rare earth fluorescent material, which is then dried at 80℃ for 12 hours.

[0008] Preparation of spinning solution: Under normal temperature conditions, prepare a clear, transparent, bubble-free polymer solution with a mass fraction of 5% to 15%. The polymer in the polymer solution is a mixture of polyester and polyamide or a combination of them and hydrophilic polymers. Add rare earth fluorescent material to the polymer solution to obtain the spinning solution and stir for 30-60 minutes.

[0009] Electrospinning preparation of nanofiber membranes: The prepared spinning solution was placed in a syringe and electrospinning was used to prepare electrospun fluorescent nanocomposite fiber membranes.

[0010] In the preparation of rare earth fluorescent materials, the ligands are one or more combinations of 2-thiophene trifluoroacetone and 2,5-thiophene dicarboxylic acid, and the rare earth compounds are one or more of europium chloride hexahydrate and terbium chloride hexahydrate.

[0011] In some embodiments, the first solution and the second solution are slowly added during continuous stirring, and NaOH solution is added under conditions of pH 5 to 7.

[0012] In the preparation of the spinning solution, the hydrophilic polymer in the polymer is one or more combinations of polyacrylic acid, polyvinyl alcohol, and polyvinylpyrrolidone, and the mass ratio of one or more of the polyester and polyamide in the polymer to the hydrophilic polymer is 24:1 to 4:1. The advantages of this design are: modifying polyester materials such as PET with a hydrophilic polymer with excellent hydrophilicity successfully prepares nanofiber composite membranes with good mechanical properties and excellent hydrophilicity; the production volume is high and the operation is simple; the advantages of the two polymers are complementary, which is beneficial for the reuse of fluorescent fiber membranes.

[0013] In some embodiments, the polymer is dissolved in a solvent and stirred on a thermostatic magnetic stirrer at a speed of 300-600 r / min for 4-8 h until a clear, transparent, bubble-free polymer solution is obtained.

[0014] In some embodiments, a spinning solution is obtained by adding 5-1000 mg / g of rare earth fluorescent material to a polymer solution.

[0015] In the electrospinning process for preparing nanofiber membranes, the prepared spinning solution is placed in a plastic syringe connected to a 22G stainless steel needle. During electrospinning, a syringe pump is used to maintain the solution flow rate at 1–5 mL / h and the voltage at 10–20 kV. The distance between the needle tip and the collecting aluminum plate is 10–20 cm. The spinning time is 2–4 hours, the spinning temperature is 25℃, and the humidity is 30%–80%.

[0016] Secondly, this solution provides an electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions, in which rare earth fluorescent materials are distributed on the surface of the superhydrophilic fiber membrane. The rare earth fluorescent materials emit strong red light under 365nm ultraviolet light and undergo fluorescence quenching after being added to a copper ion solution.

[0017] In some embodiments, the electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions is prepared using the method described above.

[0018] In some embodiments, the electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions can be recycled and reused.

[0019] In some embodiments, there is a linear relationship between copper ion concentration and fluorescence intensity.

[0020] Thirdly, this solution provides an application method for an electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions, comprising: placing the electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions in the sample to be tested and measuring the fluorescence intensity, and determining the copper ion concentration based on the detected fluorescence intensity.

[0021] In some embodiments, Cu is used for detection of 0–100 μmol / L. 2+ Solution.

[0022] In some embodiments, several electrospun fluorescent nanocomposite fiber membranes with similar mass are first prepared, and various copper ion solutions with different concentration gradients are prepared. 1 mL of standard copper ion solution is added to a container containing the electrospun fluorescent nanocomposite fiber membrane with detectable copper ions. After 1 min, the membrane is removed, dried for 20 min, and the fluorescence spectrum is tested to obtain the linear relationship between copper ions and fluorescence intensity.

[0023] Compared with existing technologies, this technical solution has the following characteristics and beneficial effects:

[0024] By modifying polyester materials such as PET with hydrophilic functional monomers, nanofiber composite membranes with good mechanical properties and excellent hydrophilicity were successfully prepared. This method boasts high yield and simple operation, achieving complementary advantages between the two polymers and facilitating the reusability of fluorescent fiber membranes. Furthermore, by attaching rare earth materials to the surface of superhydrophilic fiber membranes, the fluorescence quenching property between rare earth fluorescent materials and copper ions enables rapid detection of copper ions. This method is simple to prepare, low in cost, reusable, and suitable for rapid detection of copper ions in water. Moreover, because electrospun nanofibers fix the fluorescent material onto the matrix, the fiber membrane can be removed after testing, avoiding contamination of the sample by the detected substance, thus offering significant advantages in detection. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0027] Example 1

[0028] Preparation of rare-earth fluorescent materials: 666.1 mg of 2-thiophenecarboxyltrifluoroacetone was dissolved in 15 ml of ethanol, and 361.5 mg of europium chloride hexahydrate was dissolved in 10 ml of deionized water. The two solutions were mixed (with continuous stirring and slow addition), and NaOH solution was added to adjust the pH to 5-7. The reaction was carried out at 25 °C for 4 h. 50 ml of deionized water was added to the reacted solution to precipitate the solid, which was then centrifuged twice to obtain a yellow solid, which was then dried.

[0029] Preparation of spinning solution: At room temperature, a 10% (w / w) polyester-polyvinyl alcohol (w / w) composite polymer solution (w / w) with a mass ratio of 4:1 and a total mass of 0.2 g was stirred on a constant temperature magnetic stirrer until dissolved. The stirring speed was set to 500 r / min and stirred for 6 h. Then, 20 mg of rare earth fluorescent material was added and stirred until clear, transparent and free of bubbles.

[0030] Then, nanofiber membranes loaded with rare-earth fluorescent materials were prepared using an electrospinning machine. The prepared spinning solution was placed in a plastic syringe with a 22G stainless steel needle attached. During electrospinning, a syringe pump was used to maintain the solution flow rate at 3 mL / h. The voltage was maintained at 15 kV. The distance between the needle tip and the collecting aluminum plate was 15 cm. The spinning time was 3 hours, the spinning temperature was 25 °C, and the humidity was 50%.

[0031] The prepared electrospun fluorescent nanocomposite fiber membrane exposes rare-earth fluorescent materials on its surface, emitting strong red light under ultraviolet light. The optimal excitation wavelength is 365 nm, and the strongest emission wavelength at 365 nm is 616 nm, located in the red light range of the visible spectrum. The steps for using this electrospun fluorescent nanocomposite fiber membrane to detect copper ions in environmental water are as follows: First, several samples of electrospun fluorescent nanocomposite fiber membranes of similar mass are prepared. Various copper ion solutions of different concentration gradients are prepared. 1 mL of standard copper ion solution is added to a container containing the electrospun fluorescent nanocomposite fiber membrane. After 1 minute, the membrane is removed and dried. The fluorescence spectrum is then measured. The surface of the electrospun fluorescent nanocomposite fiber membrane exhibits a strong red color under ultraviolet light irradiation, visible to the naked eye. However, when copper ion solution is added, the red intensity on the surface of the electrospun fluorescent nanocomposite fiber membrane significantly decreases, eventually becoming difficult to observe.

[0032] Cu with concentrations of 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 μmol / L 2+ The solution was dropped onto the surface of an electrospun fluorescent nanocomposite fiber membrane, and fluorescence was detected sequentially using a fluorescence spectrometer. With Cu... 2+ With increasing ion concentration, the emission peak at 616 nm on the surface of the electrospun fluorescent nanocomposite fiber membrane gradually decreases until it is completely quenched. The change in fluorescence intensity has a linear relationship with the copper ion concentration, which can be used to quantitatively detect the presence of copper ions in water.

[0033] The electrospun fluorescent nanocomposite fiber membrane prepared by this method can detect Cu in the range of 0–100 μmol / L on its surface. 2+ Solution. Therefore, the quenching mechanism of this electrospun fluorescent nanocomposite fiber membrane prepared in this study is sufficient to detect Cu in human blood and drinking water. 2+ It is of high quality and has high practical value.

[0034] Example 2

[0035] Preparation of rare earth fluorescent materials: 666.1 mg of 2-thiophenecarboxyltrifluoroacetone was dissolved in 15 ml of ethanol, and 361.5 mg of europium chloride hexahydrate was dissolved in 10 ml of deionized water. The two solutions were mixed (with continuous stirring and slow addition), and NaOH solution was added to adjust the pH to 6. The reaction was carried out at 25 °C for 7 h. 50 ml of deionized water was added to the solution after the reaction to precipitate the solid. The solid was centrifuged twice to obtain a yellow solid, which was then dried.

[0036] Preparation of spinning solution: At room temperature, a 10% polyamide-polyacrylic acid (mass ratio of 4:1, total mass of 0.2g) composite polymer solution (solvent such as hexafluoroisopropanol) was stirred on a constant temperature magnetic stirrer until dissolved. The stirring speed was set to 400r / min and stirred for 5h. Then, 20mg of rare earth fluorescent material was added and stirred until clear, transparent and free of bubbles.

[0037] Then, nanofiber membranes loaded with rare-earth fluorescent materials were prepared using an electrospinning machine. The prepared spinning solution was placed in a plastic syringe with a 22G stainless steel needle attached. During electrospinning, a syringe pump was used to maintain the solution flow rate at 2 mL / h, the voltage at 10 kV, the distance between the needle tip and the collecting aluminum plate at 20 cm, and the spinning time at 4 hours. The spinning temperature was 25℃, and the humidity was 30%–80%.

[0038] The prepared electrospun fluorescent nanocomposite fiber membrane exposes rare earth fluorescent materials and emits strong red light under ultraviolet light; the optimal excitation wavelength is 365nm, and the strongest emission wavelength at the 365nm excitation wavelength is 616nm, which is located in the red light range of the visible light spectrum.

[0039] The steps for detecting copper ions in environmental water using this electrospun fluorescent nanocomposite fiber membrane are as follows: First, prepare several electrospun fluorescent nanocomposite fiber membranes of similar mass, and then prepare various concentration gradients of Cu. 2+ Solution, measure 1 mL of standard Cu 2+ The solution was added to a container containing an electrospun fluorescent nanocomposite fiber membrane. After 1 minute, the membrane was removed, dried, and its fluorescence spectrum was measured.

[0040] The electrospun fluorescent nanocomposite fiber membrane exhibits a strong red color under ultraviolet light irradiation and is visible to the naked eye. When Cu is added... 2+ After solution treatment, the red intensity of the electrospun fluorescent nanocomposite fiber membrane decreased significantly and eventually became difficult to observe. Cu at concentrations of 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 μmol / L was then applied. 2+ The solution was dropped onto electrospun fluorescent nanocomposite fiber membranes, and fluorescence was detected sequentially using a fluorescence spectrometer. With Cu... 2+With increasing ion concentration, the emission peak of the electrospun fluorescent nanocomposite fiber membrane at 616 nm gradually decreases until it is completely quenched. The change in fluorescence intensity shows a linear relationship with the copper ion concentration, which can be used for the quantitative detection of copper ions in water.

[0041] The electrospun fluorescent nanocomposite fiber membrane prepared by this method can detect Cu in the range of 0–100 μmol / L. 2+ Solution. Therefore, the quenching mechanism of this electrospun fluorescent nanocomposite fiber membrane prepared in this study is sufficient to detect Cu in human blood and drinking water. 2+ It is of high quality and has high practical value.

[0042] Example 3

[0043] The electrospun fluorescent nanocomposite fiber membrane with fluorescence quenching from Example 1 was used for reusability testing. The electrospun fluorescent nanocomposite fiber membrane was titrated with 0.1 mol / L EDTA chelated copper ions to verify the Cu content. 2+ The "on-off-on" detection was performed. After titration with EDTA, the fluorescence of the electrospun fluorescent nanocomposite fiber membrane recovered. This is because the ligands containing N and O functional groups affect Cu... 2+ It has a strong affinity. Energy is transferred to Cu. 2+ It quenches the fluorescence of the Eu(TTA)3 complex, while EDTA can chelate copper ions to restore fluorescence. Experiments have shown that EDTA is a good Cu chelate ion chelate. 2+ The source of the thin film fluorescence change is turned off, thus achieving the goals of reuse and environmental protection.

[0044] Comparative Example 1

[0045] Preparation of rare earth fluorescent materials: 666.1 mg 2-thiophenecarboxyltrifluoroacetone was dissolved in 15 ml ethanol, and 361.5 mg europium chloride hexahydrate was dissolved in 10 ml deionized water. The two solutions were mixed (with continuous stirring and slow addition), and NaOH solution was added to adjust the pH to 6. The reaction was carried out at 25 °C for 6 h. 50 ml of deionized water was added to the solution after the reaction to precipitate the solid. The solid was centrifuged twice to obtain a yellow solid, which was then dried.

[0046] The steps for detecting copper ions in environmental water using this rare-earth fluorescent material are as follows: First, prepare several samples of rare-earth fluorescent material of similar mass, and then prepare various concentration gradients of Cu. 2+ Solution, measure 1 mL of standard Cu 2+ The solution was added to a container containing rare earth fluorescent material, and the fluorescence spectrum was measured after 1 minute.

[0047] Rare earth fluorescent materials exhibit a strong red color under ultraviolet light and are visible to the naked eye. When Cu is added... 2+After solution treatment, the red intensity of the rare-earth fluorescent material decreased significantly, eventually becoming difficult to observe. Cu at concentrations of 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 μmol / L were then applied. 2+ The solutions were dropped onto rare-earth fluorescent materials, and fluorescence detection was performed sequentially using a fluorescence spectrometer. With the increase of Cu... 2+ With increasing ion concentration, the emission peak of the rare-earth fluorescent material at 616 nm gradually decreases until it is completely quenched. The change in fluorescence intensity has a linear relationship with the copper ion concentration, which can be used for the quantitative detection of the presence of copper ions in water.

[0048] Examples 1, 2 and Comparative Example 1 can all detect copper ions in water, but the fiber membrane produced by electrospinning can be reused and does not cause secondary pollution, which has a significant advantage in detection.

[0049] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0050] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for preparing electrospun fluorescent nanocomposite fiber membranes capable of detecting copper ions, characterized in that, The method comprises the following steps: Preparation of the rare earth fluorescent material: a first solution is prepared by dissolving a ligand in ethanol, the ligand being one or more of 2-thiophene trifluoroacetone and 2,5-thiophene dicarboxylic acid, and a second solution is prepared by dissolving one or more of europium chloride hexahydrate and terbium chloride hexahydrate in deionized water, wherein the molar ratio of the ligand to the rare earth ion is 1-5:1; the first solution and the second solution are mixed, and the pH is adjusted to 5-7, and then the mixture is reacted at 25°C for 4-8 hours; after the reaction, deionized water is added to the solution to precipitate, and the solution is centrifuged twice to obtain a yellow solid as the rare earth fluorescent material, which is dried at 80°C for 12 hours; Preparation of the spinning solution: a clear, transparent, and bubble-free polymer solution with a mass fraction of 5%-15% is prepared at room temperature, wherein the polymer in the polymer solution is a mixture of one or a combination of polyester and polyamide and a hydrophilic polymer; the rare earth fluorescent material is added to the polymer solution to obtain the spinning solution, and the mixture is stirred for 30-60 minutes; Preparation of the nanofiber membrane by electrospinning: the prepared spinning solution is placed in a syringe, and an electrospinning technique is used to prepare an electrospinning fluorescent nanocomposite fiber membrane, wherein the rare earth fluorescent material of the electrospinning fluorescent nanocomposite fiber membrane is distributed on the surface of the super-hydrophilic fiber membrane, and the copper ion concentration and the fluorescence intensity have a linear relationship.

2. The method for preparing an electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions according to claim 1, characterized in that, The hydrophilic polymer in the polymer is one or more of polyacrylic acid, polyvinyl alcohol, and polyvinylpyrrolidone, and the mass ratio of the polyester and the polyamide in the polymer to the hydrophilic polymer is 24:1-4:

1. 3.The method of claim 1, wherein the electrospun fluorescent nanocomposite fiber membrane is prepared by electrospinning a solution of a copper ion-detectable fluorescent polymer and a copper ion-detectable fluorescent polymer precursor. The rare earth fluorescent material is added to the polymer solution in an amount of 5-1000 mg / g to obtain the spinning solution.

4. The method for preparing an electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions according to claim 1, characterized in that, During the electrospinning process, the solution flow rate is maintained at 1-5 mL / h by using a syringe pump, the voltage is maintained at 10-20 kV, the distance between the needle tip and the collection aluminum plate is 10-20 cm, the spinning time is 2-4 hours, the spinning temperature is 25°C, and the humidity is 30%-80%.

5. An electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions, characterized in that, The rare earth fluorescent material is distributed on the surface of the super-hydrophilic fiber membrane, wherein the rare earth fluorescent material emits strong red light under 365 nm ultraviolet light, and the fluorescence is quenched after being added to a copper ion solution, and the electrospinning fluorescent nanocomposite fiber membrane for detecting copper ions is prepared by using the method described in any one of claims 1 to 4.

6. The application method of the electrospun fluorescent nanocomposite fiber membrane capable of detecting copper ions according to claim 5, characterized in that, The electrospinning fluorescent nanocomposite fiber membrane for detecting copper ions is placed in a sample to be measured to measure the fluorescence intensity, and the copper ion concentration is determined according to the detected fluorescence intensity.

7. The method of claim 6, wherein the electrospun fluorescent nanocomposite fiber membrane for detecting copper ions is used for the following applications. For detection of Cu from 0 to 100 pmol / L 2+ solution.