Copper ion visualized rapid detection fiber membrane, and preparation method and application thereof

Abstract

This invention discloses a copper ion visualization rapid detection fiber membrane, its preparation method, and its application. Bicyclohexanone oxaloyl dihydrazone (BCO) is selected as the identification probe, and for the first time, it is in-situ encapsulated within PVDF / PAN / PVP ternary polymer nanofibers via a one-step electrospinning process with a Tris buffer system. This significantly improves the stability and batch consistency of the sensing material, ensuring that copper-containing water samples can quickly penetrate into the fiber and fully contact the probe, while maintaining the integrity and stability of the fiber membrane's skeletal structure. The fiber membrane provides rapid, intuitive, and verifiable detection of copper-containing water samples. The preparation process is simple, controllable, and low-cost, making it suitable for large-scale application.

Description

Technical Field

[0001] This invention belongs to the field of environmental monitoring technology, specifically relating to functional materials and detection technologies, and more specifically to a copper ion visualization rapid detection fiber membrane and its preparation method and application. Background Technology

[0002] heavy metal copper ions (Cu) 2+ Copper-containing wastewater is a typical water pollutant, and excessive intake can cause serious harm to human health and aquatic ecosystems. Large quantities of copper-containing wastewater generated by industrial activities such as electroplating, metallurgy, printing and dyeing, electronic dismantling, and mining, if illegally discharged without effective treatment, will cause severe water pollution. In actual environmental law enforcement, the illegal discharge of copper-containing wastewater is characterized by its covert nature, nighttime discharge, and easy loss of evidence. Pollution plumes are rapidly diluted and dispersed with water flow, and by the time law enforcement officers arrive at the scene or samples are sent back to the laboratory for testing, crucial evidence is often lost. Traditional laboratory testing methods (such as atomic absorption spectrometry, inductively coupled plasma mass spectrometry, and electrochemical sensor methods), while highly sensitive and quantitatively accurate, generally rely on large, precision instruments, involve cumbersome sample pretreatment, and have long testing cycles (from several hours to several days), failing to meet the practical needs of on-site evidence collection and preservation in environmental law enforcement.

[0003] Colorimetric sensing produces visually perceptible color changes by reacting chromogenic materials with target ions, directly converting chemical signals into intuitive optical signals. It has significant advantages such as simple operation, fast response, and no need for complex instruments. However, existing electrospun fiber membrane-based copper ion colorimetric sensors still have the following core shortcomings: (1) poor selectivity and insufficient sensitivity of the identification probes, with some natural dye probes showing weak color response; (2) probes are mostly introduced through post-modification, immersion loading, etc., resulting in uneven probe distribution, easy detachment and loss, and poor long-term stability; (3) it is difficult to balance the hydrophilicity and structural stability of the fiber membrane; (4) the sensor has a narrow working pH window, and most are only effective under neutral conditions (pH 6~7), making it difficult to adapt to the wide range of acid and alkali fluctuations in actual water bodies. Summary of the Invention

[0004] To address the problems of low sensitivity, poor selectivity, insufficient environmental adaptability, and lack of field applicability of existing copper ion detection materials, this invention discloses a copper ion visualization rapid detection fiber membrane, its preparation method, and its application. This membrane can be used for detecting copper ions (Cu) in water. 2+ It provides rapid, visual colorimetric detection on-site, making it particularly suitable for scenarios such as environmental law enforcement, emergency monitoring, and on-site screening of industrial wastewater.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A copper ion visualization rapid detection fiber membrane has a three-dimensional porous interconnected network structure. It uses BCO as a copper ion specific recognition colorimetric probe, PVDF, PAN and PVP ternary blend polymer as a composite carrier matrix, and Tris base as a buffer system. It is prepared by a one-step solution blending-electrospinning method. The BCO colorimetric probe and Tris buffer are uniformly dispersed and in-situ encapsulated inside the nanofibers in the fiber membrane.

[0007] Furthermore, in the composite carrier matrix, the mass ratio of PAN to PVP is 2:8 to 5:5, and the amount of PVDF added is 0.5 to 2 wt% of the total mass of PAN and PVP.

[0008] Furthermore, the amount of BCO chromogenic probe added is 0.1~0.5 wt% of the total mass of PAN and PVP.

[0009] Furthermore, the amount of Tris base added is 0.2~1.0 wt% of the total mass of PAN and PVP.

[0010] A method for preparing a copper ion visualization rapid detection fiber membrane includes the following steps:

[0011] Step 1, Preparation of pre-spinning solution: Add PAN, PVP and PVDF to DMF solvent in proportion, then add BCO color developer and Tris base buffer, and stir magnetically at room temperature until a homogeneous composite spinning solution is formed.

[0012] Step 2, electrospinning: The spinning solution is injected into a syringe with a metal needle, and electrospinning is performed under the action of a high voltage electric field;

[0013] Step 3, Post-processing: The obtained fiber membrane is air-dried at room temperature to remove residual solvent, and then stored in a sealed container away from light.

[0014] Furthermore, in step 1, polymer powder is weighed at a PAN to PVP mass ratio of 2:8 to 5:5; the amount of PVDF added is 0.5 to 2 wt% of the total mass of PAN and PVP; the amount of BCO colorimetric probe added is 0.1 to 0.5 wt% of the total mass of PAN and PVP; the amount of Tris base added is 0.2 to 1.0 wt% of the total mass of PAN and PVP; and the total mass fraction of the terpolymer blend of PVDF, PAN, and PVP in the spinning solution is 10 to 20%.

[0015] Furthermore, in step 1, the solvent is DMF.

[0016] Furthermore, in step 2, the spinning parameters are: voltage 10~20 kV, receiving distance 15~25 cm, feed rate 1.0~2.0 mL / h, receiving drum speed 80~150 r / min, ambient temperature 20~30 ℃, and spinning time 4~6 h.

[0017] Furthermore, in step 3, the air-drying time is 8-12 hours.

[0018] Application of a copper ion visualization rapid detection fiber membrane in the rapid on-site visualization detection of copper ions in environmental water bodies.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. This invention selects bicyclohexanone oxaloyl dihydrazone (BCO), a classic chromogenic reagent with high specificity and sensitivity to copper ions, as a recognition probe. For the first time, it integrates BCO with a Tris buffer system via electrospinning and in-situ encapsulates it within PVDF / PAN / PVP ternary polymer nanofibers. This method fundamentally differs from traditional probe introduction methods such as post-modification and immersion loading. It achieves molecular-level uniform dispersion and stable fixation of functional components (chromogenic probe and buffer) within the fiber, effectively avoiding probe detachment, loss, aggregation inactivation, and uneven distribution. This significantly improves the stability and batch consistency of the sensing material.

[0021] 2. This invention constructs a PVDF / PAN / PVP ternary composite nanofiber carrier system. PVDF imparts excellent chemical stability and mechanical flexibility to the fiber membrane, PAN provides excellent spinnability and mechanical support for the fiber skeleton, and PVP regulates the surface wettability of the fiber membrane, achieving complementary and synergistic functions among the three. This system fundamentally solves the contradiction between the excessive hydrophobicity of pure PAN / PVDF binary membranes leading to difficulty in water sample penetration and the excessive hydrophilicity of pure PAN / PVP membranes leading to fiber swelling and damage. It ensures that copper-containing water samples can quickly wet and penetrate into the fiber interior to fully contact the probe, while the fiber membrane skeleton structure remains intact and stable.

[0022] 3. This invention introduces a Tris buffer system in situ within the fiber, maintaining a favorable environment for BCO-Cu in the fiber surface microenvironment. 2+ The weakly alkaline conditions of the chelation reaction significantly broaden the effective working pH window of the sensing membrane from the conventional narrow neutral range (pH 6-7) to pH 4.0-10.0, while also providing stable response capability over a wide temperature range of 4-60 °C, and enhancing its resistance to Na+. + Ca 2+The sensor exhibits excellent anti-interference performance against common coexisting ions. This characteristic enables the sensor fiber membrane to meet the diverse and complex real-world water sample testing needs, including electroplating wastewater (strongly acidic), mining drainage (acidic), and dyeing and papermaking wastewater (alkaline), significantly improving its practical application.

[0023] 4. Upon contact with a copper-containing aqueous sample, the fiber membrane exhibits a visually perceptible color change (from white to blue) within 5-10 seconds, and the color stabilizes within 20 seconds; the color intensity varies with the Cu content. 2+ The concentration exhibits a favorable positive correlation gradient (from light blue to dark blue), with a visually detectable limit of 0.1 μg / mL, far below the Class I emission limit for copper in the integrated wastewater discharge standard. The colorimetric results can be directly interpreted visually or analyzed using RGB quantification with a mobile phone. The developed membrane can be sealed and preserved as physical evidence and transferred to the laboratory for verification along with the case file. This meets the needs of environmental law enforcement for establishing a rapid on-site screening-laboratory verification evidence chain, providing fast, intuitive, and verifiable evidence.

[0024] 5. This invention employs mature electrospinning technology, using commercially available conventional industrial reagents. The preparation process is simple, controllable, and low-cost, requiring no complex subsequent chemical modification steps. The optimized spinning process parameters exhibit excellent repeatability and batch stability. The resulting fiber membrane is thin, flexible, and can be cut to any size, making it easy to carry and store. It requires no external power supply or large-scale equipment, making it suitable for on-site use by grassroots environmental enforcement teams and for large-scale application. Attached Figure Description

[0025] Figure 1 This is a comparison chart of the color development of copper ions by the BCO colorimetric reagent selected in Example 1, compared with those by shellac red and polyethyleneimine.

[0026] Figure 2 Scanning electron microscope (SEM) of the fiber membrane prepared in Example 2.

[0027] Figure 3 The water contact angle of the fiber membrane prepared in Example 2;

[0028] Figure 4 The composite fiber membrane prepared in Example 14 was contacted with Cu at different reaction times (0s, 5s, 10s, 20s). 2+ Colorimetric effect of the solution;

[0029] Figure 5 The composite fiber membrane prepared in Example 14 is effective against different concentrations of Cu. 2+ Colorimetric effect of the solution;

[0030] Figure 6 The composite fiber membrane prepared in Example 14 was subjected to different pH conditions for Cu2+ The color rendering effect of ⁺;

[0031] Figure 7 The composite fiber membrane prepared in Example 14 was subjected to different ambient temperature conditions for Cu 2+ The color response effect diagram;

[0032] Figure 8 The composite fiber membrane prepared in Example 14 was subjected to Na... + Cu 2+ Zn 2+ Comparison of selective color development effects under coexisting ion interference conditions. Detailed Implementation

[0033] The technical solutions provided by the present invention will be described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0034] Example 1:

[0035] This embodiment illustrates the superiority of BCO over other candidate chromogenic agents and verifies the scientific basis for the selection of the recognition probe. For example... Figure 1 As shown, three candidate colorimetric reagents were selected for comparative experiments: (1) BCO, (2) lac red, and (3) polyethyleneimine (PEI). Equal volumes of aqueous solutions of each of the three colorimetric reagents were prepared. 2 mL of each solution was placed in a standard colorimetric tube, and an equal volume of 1×10⁻³ mol / L CuSO₄ solution was added. After standing at room temperature for 5-10 seconds, the colorimetric state was observed. The experimental results are as follows: Figure 1 As shown, in the lac red system, the solution color only slightly shifts from the initial bright red to orange-red, and the difference is difficult to distinguish with the naked eye. This is because lac red is a natural anthraquinone dye, and its color is determined solely by the interaction of the hydroxyl and carboxyl groups in its molecule with Cu. 2+ Weak coordination occurs, and the coordination effect has little impact on the conjugated chromophore system of the anthraquinone parent nucleus, producing only a slight shift in absorption wavelength. In the PEI system, the addition of Cu... 2+ The solution later changed from colorless to light blue, with a low degree of color response. This is because PEI is an amino-containing polymer, although it can react with Cu through amino groups. 2+ Coordination occurs, but the resulting visible light absorption band is narrow, leading to poor color development. In the BCO system, the solution reacts with Cu... 2+ Upon contact, it rapidly changes from white to its characteristic sky blue; the color reaction is significant and easily observed with the naked eye. This is because the BCO molecule contains a hydrazine group and a conjugated hydrazone structure (-C=N-NH-), and its hydrazone nitrogen atom and carbonyl oxygen atom can react with Cu. 2+Specific coordination chelation occurs, forming a stable planar chelate, which significantly enhances the intramolecular conjugated system, causing the absorption wavelength to shift from the ultraviolet region to the visible light region, thus producing a strong characteristic blue color. Considering key indicators such as color development effect, sensitivity, and selectivity, BCO was determined to be the optimal copper ion-specific colorimetric probe.

[0036] Example 2:

[0037] This embodiment provides a copper ion visualization and rapid detection fiber membrane, which uses dicyclohexanone oxaloyl dihydrazone (BCO) as a copper ion-specific colorimetric probe, a ternary blend of polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyvinylpyrrolidone (PVP) as a composite carrier matrix, and tris(hydroxymethyl)aminomethane (Tris base) as a buffer system, and is prepared by a one-step solution blending-electrospinning method. The fiber membrane has a three-dimensional porous interconnected network structure.

[0038] This embodiment provides a method for preparing a copper ion visualization rapid detection fiber membrane, including the following steps:

[0039] (1) Preparation of spinning precursor solution

[0040] Weigh out polymer powder at a PAN to PVP mass ratio of 3:7 and add it to DMF solvent. Then add PVDF at a mass ratio of 1.5 wt% of the total mass of PAN and PVP, followed by 0.25 wt% of BCO color developer and 0.5 wt% of tris(hydroxymethyl)aminomethane (Tris base) buffer to adjust the total mass fraction of the PAN, PVP, and PVDF ternary blend polymer to 15%. Perform initial dispersion by magnetic stirring at room temperature for 1 hour, followed by continued magnetic stirring at room temperature for 3 hours until a homogeneous, transparent, and particle-free BCO / PVDF / PAN / PVP composite spinning solution is formed.

[0041] (2) Preparation of fiber membranes by electrospinning

[0042] The prepared spinning solution was injected into a 10 mL syringe, and a needle with an inner diameter of 0.5 mm was attached. A self-made electrospinning apparatus was used for spinning, with the following parameters: high voltage of 15 kV, distance between the needle and the receiving plate (aluminum foil) of 20 cm, spinning solution feed rate of 1.5 mL / h, receiving roller speed of 200 r / min, ambient temperature controlled at 25±2 ℃, and relative humidity of 30%~40%. After turning on the high voltage power supply and the feed pump, the spinning solution overcame surface tension under the action of the high voltage electric field to form a Taylor cone, thereby generating a continuous jet. The jet underwent whipping stretching and solvent evaporation in the electric field to form nanofibers, which were uniformly deposited on the aluminum foil receiving plate. Spinning was continued for 6 h to obtain a white fiber membrane of uniform thickness.

[0043] (3) Post-processing

[0044] After spinning, the resulting fiber membrane was carefully peeled off the aluminum foil and air-dried at room temperature for 12 hours to completely remove any residual DMF solvent. The fiber membrane was then placed in a desiccator and sealed for storage in the dark for later use.

[0045] (4) Product structure characteristics

[0046] Observed by scanning electron microscopy (SEM), such as Figure 2 As shown, the prepared BCO / PVDF / PAN / PVP composite nanofiber membrane has a smooth surface, uniform thickness, and is free from defects such as beading, adhesion, and filament twisting. The fibers are randomly oriented and three-dimensionally interwoven, forming a well-developed hierarchical porous network structure. The BCO chromogenic probe and Tris buffer are uniformly dispersed and in-situ encapsulated within the nanofibers in the fiber membrane. Water contact angle testing shows that... Figure 3 As shown, the water contact angle of the fiber membrane is 64°, indicating moderate hydrophilicity.

[0047] Example 3:

[0048] The difference between this embodiment and Embodiment 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the mass ratio of PAN to PVP is 2:8, while the rest of the structure and preparation method are the same as in Embodiment 2.

[0049] Example 4:

[0050] The difference between this embodiment and Embodiment 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the mass ratio of PAN to PVP is 5:5, while the rest of the structure and preparation method are the same as in Embodiment 2.

[0051] Example 5:

[0052] The difference between this embodiment and Embodiment 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the added PVDF accounts for 0.5 wt% of the total polymer mass, while the remaining structure and preparation method are the same as in Embodiment 2.

[0053] Example 6:

[0054] The difference between this embodiment and Embodiment 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the added PVDF accounts for 2wt% of the total polymer mass, while the remaining structure and preparation method are the same as in Embodiment 2.

[0055] Example 6:

[0056] The difference between this embodiment and Embodiment 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the amount of BCO colorimetric probe added is 0.1 wt% of the total polymer mass, while the rest of the structure and preparation method are the same as in Embodiment 2.

[0057] Example 7:

[0058] The difference between this embodiment and Embodiment 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the amount of BCO colorimetric probe added is 0.5 wt% of the total polymer mass, while the rest of the structure and preparation method are the same as in Embodiment 2.

[0059] Example 8:

[0060] The difference between this embodiment and Example 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the amount of tris(hydroxymethyl)aminomethane (Tris base) buffer added is 0.2 wt% of the total polymer mass, while the rest of the structure and preparation method are the same as in Example 2.

[0061] Example 9:

[0062] The difference between this embodiment and Example 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the amount of tris(hydroxymethyl)aminomethane (Tris base) buffer added is 1.0 wt% of the total polymer mass, while the remaining structure and preparation method are the same as in Example 2.

[0063] Example 10:

[0064] The difference between this embodiment and Embodiment 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the total mass fraction of the polymer is controlled to be 10%, while the remaining structure and preparation method are the same as in Embodiment 2.

[0065] Example 11:

[0066] The difference between this embodiment and Embodiment 2 is that, when preparing the copper ion visualization rapid detection fiber membrane, the total mass fraction of the polymer is controlled to be 20%, while the remaining structure and preparation method are the same as in Embodiment 2.

[0067] Example 12:

[0068] The difference between this embodiment and Embodiment 2 is that the spinning parameters for preparing the copper ion visualization rapid detection fiber membrane are as follows: spinning voltage 10kV; receiving distance 15cm; spinning solution feed rate 1.0mL / h; receiving drum speed 80r / min; spinning ambient temperature 20℃; spinning time 4h. After spinning, the fiber membrane is air-dried at room temperature for 8h. The remaining structure and preparation method are the same as in Embodiment 2.

[0069] Example 13:

[0070] The difference between this embodiment and Embodiment 2 is that the spinning parameters for preparing the copper ion visualization rapid detection fiber membrane are as follows: spinning voltage 20 kV; receiving distance 25 cm; spinning solution feed rate 2.0 mL / h; receiving drum speed 400 r / min; spinning ambient temperature 30 ℃; spinning time 5 h. After spinning, the fiber membrane is air-dried at room temperature for 10 h. The remaining structure and preparation method are the same as in Embodiment 2.

[0071] Scanning electron microscopy (SEM) revealed that the BCO / PVDF / PAN / PVP composite nanofiber membranes prepared in Examples 3-13 had smooth, uniform fiber surfaces and were free from defects such as beading, adhesion, or filament twisting. The fibers exhibited a randomized, three-dimensionally interwoven stacked structure, displaying a multi-level pore structure with both mesopores and micropores. The fiber diameters of the membranes were primarily distributed in the range of 200–500 nm. Water contact angle tests showed that the water contact angles of the fiber membranes ranged from 55° to 75°.

[0072] Example 14:

[0073] This embodiment mainly verifies the sensitivity of copper ion detection, pH adaptability, temperature adaptability, and resistance to ion interference of the composite fiber membrane.

[0074] (1) Sensitivity of copper ion detection

[0075] The fiber membrane prepared in Example 2 was cut into circular membrane pieces with a diameter of 1 cm, and the water sample to be tested (Cu was used in this example) was dropped onto it. 2+ Observe the color change of the membrane by placing the solution at the center of the membrane. Figure 4 As shown, under natural light conditions, the diaphragm contacts Cu 2+ The solution appears as a light blue color visible to the naked eye in about 5 seconds, and the blue color deepens significantly within 10 seconds. It reaches a stable color development state at 20 seconds, after which no further color change occurs, and there is no fading or uneven color difference.

[0076] When the fiber membrane of this invention is used for testing, the water sample to be tested includes, but is not limited to, any one or more of the following: surface water, groundwater, domestic sewage, industrial wastewater (including electroplating wastewater, dyeing and printing wastewater, and acidic mine drainage), and copper-containing pesticide runoff.

[0077] (2) Limit of detection for copper ions

[0078] Cu at different concentrations 2+ Colorimetric tests were performed in solutions (0.1, 0.5, 1.0, 5.0, 10.0, 20.0 μg / mL). The membrane exhibited a continuous gradient colorimetric response from very light blue to deep blue, as shown in the results. Figure 5As shown, a light blue color is visible to the naked eye at a low concentration of 0.1 μg / mL, reaching a deep blue at 20.0 μg / mL. The detection limit for visual observation is as low as 0.1 μg / mL. The color intensity is related to Cu. 2+ The concentrations within the range of 0.1 to 20.0 μg / mL show a positive correlation, enabling on-site semi-quantitative detection.

[0079] (2) pH adaptability

[0080] Cu with a concentration of 1.0 μg / mL was dissolved in HCl and NaOH solution. 2+ The pH values ​​of the standard solutions were adjusted to seven gradients: 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, and 10.0. The prepared fiber membranes were then immersed in Cu solutions at each of these pH conditions. 2+ A colorimetric reaction was carried out in the solution, and the results were recorded. The experimental results are as follows: Figure 6 As shown, the membrane exhibited a visible blue response throughout the entire pH range of 4.0–10.0. The color was most pronounced in the pH range of 7.0–9.0, and while it slightly weakened under strongly acidic conditions (pH 4.0–5.0), it remained recognizable. These results confirm that the Tris buffer system effectively buffers and shields pH in the microenvironment of the fiber surface, significantly expanding the effective working pH window from the narrow neutral range (pH 6–7) of traditional BCO solutions to pH 4.0–10.0.

[0081] (2) Temperature adaptability

[0082] The fiber membrane's resistance to 1.0 μg / mL Cu was tested at four temperatures: 4 ℃, 25 ℃, 40 ℃, and 60 ℃. 2+ The colorimetric response time and colorimetric intensity of the solution. Experimental results are as follows: Figure 7 As shown, as the temperature increased from 4 °C to 60 °C, the response time of the membrane to copper ions gradually decreased from 177.5 s to 73.5 s. Throughout the entire temperature range of 4–60 °C, the membrane consistently exhibited a stable, visually perceptible blue response, without any failure or abnormal discoloration. Temperature primarily affects the reaction kinetics (Cu... 2+ The diffusion rate and chelation reaction rate, rather than thermodynamic equilibrium, are factors influencing the final equilibrium color depth and hue. The BCO-Cu chelate exhibits a high thermodynamic stability constant, ensuring that the color depth and hue remain essentially constant within the test temperature range. This characteristic indicates that when using this membrane for on-site testing under different seasonal and climatic conditions, as long as sufficient development time is ensured for the reaction to reach equilibrium, the final interpretation results will not be systematically biased due to temperature differences.

[0083] (3) Resistance to ion interference

[0084] With 1.0 μg / mL Cu 2+ As the target, 100 μg / mL (100-fold concentration) of Na was introduced. + Ca 2+ Zn 2+ Three typical coexisting ions, along with pure interfering ions (excluding Cu) were also included. 2+ The blank control group was used. The experimental results are as follows: Figure 8 As shown, pure Na + Pure Ca 2+ Pure Zn 2+ No color development was observed in the ion blank control group, verifying the high specificity of the BCO probe for copper ions. Under coexistence conditions, Cu 2+ +Na + and Cu 2+ +Ca 2+ The color development was a typical blue, which was determined to be either no interference or slight interference, respectively; Cu 2 + +Zn 2+ The color development was light blue, indicating a certain degree of competitive interference (under 100-fold overdosing). This result is consistent with the coordination chemical structure characteristics of the BCO molecule—the oxaloyl dihydrazone skeleton of BCO interacts with Cu. 2+ d 9 The electronic configuration and ionic radius exhibit optimal geometric matching and chelation stability constant. Overall, the fibrous membrane demonstrates good adhesion to Na+, a common component in water. + Ca 2+ Alkali metal and alkaline earth metal ions have good anti-interference capabilities, and Zn in actual water bodies 2+ Even with concentrations typically far below the 100-fold overload conditions set in experiments, the membrane still exhibits reliable selectivity in real, complex water bodies.

[0085] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A copper ion visualization rapid detection fiber membrane, having a three-dimensional porous interconnected network structure, characterized in that, Using BCO as a copper ion-specific colorimetric probe, PVDF, PAN, and PVP ternary blend polymers as a composite carrier matrix, and Tris base as a buffer system, the fiber membrane was prepared by a one-step solution blending-electrospinning method. The BCO colorimetric probe and Tris buffer were uniformly dispersed and in situ encapsulated inside the nanofibers.

2. The copper ion visualization rapid detection fiber membrane according to claim 1, characterized in that, In the composite carrier matrix, the mass ratio of PAN to PVP is 2:8 to 5:5, and the amount of PVDF added is 0.5 to 2 wt% of the total mass of PAN and PVP.

3. The copper ion visualization rapid detection fiber membrane according to claim 1, characterized in that, The amount of BCO colorimetric probe added is 0.1~0.5 wt% of the total mass of PAN and PVP.

4. The copper ion visualization rapid detection fiber membrane according to claim 1, characterized in that, The amount of Tris base added is 0.2~1.0 wt% of the total mass of PAN and PVP.

5. A method for preparing a copper ion visualization rapid detection fiber membrane, characterized in that, Includes the following steps: Step 1, Preparation of pre-spinning solution: Add PAN, PVP and PVDF to DMF solvent in proportion, then add BCO color developer and Tris base buffer, and stir magnetically at room temperature until a homogeneous composite spinning solution is formed. Step 2, electrospinning: The spinning solution is injected into a syringe with a metal needle, and electrospinning is performed under the action of a high voltage electric field; Step 3, Post-processing: The obtained fiber membrane is air-dried at room temperature to remove residual solvent, and then stored in a sealed container away from light.

6. The method for preparing the copper ion visualization rapid detection fiber membrane according to claim 5, characterized in that, In step 1, polymer powder is weighed at a PAN to PVP mass ratio of 2:8 to 5:5, the amount of PVDF added is 0.5 to 2 wt% of the total polymer mass; the amount of BCO colorimetric probe added is 0.1 to 0.5 wt% of the total mass of PAN and PVP; the amount of Tris base added is 0.2 to 1.0 wt% of the total mass of PAN and PVP; and the total mass fraction of the ternary blend polymer of PVDF, PAN, and PVP in the spinning solution is 10 to 20%.

7. The method for preparing the copper ion visualization rapid detection fiber membrane according to claim 5, characterized in that, In step 1, the solvent is DMF.

8. The method for preparing the copper ion visualization rapid detection fiber membrane according to claim 5, characterized in that, In step 2, the spinning parameters are: voltage 10~20 kV, receiving distance 15~25 cm, feed rate 1.0~2.0 mL / h, receiving drum speed 80~150 r / min, ambient temperature 20~30 ℃, and spinning time 4~6 h.

9. The method for preparing the copper ion visualization rapid detection fiber membrane according to claim 5, characterized in that, In step 3, the air-drying time is 8-12 hours.

10. The application of a copper ion visualization rapid detection fiber membrane as described in any one of claims 1-4 in the rapid on-site visualization detection of copper ions in environmental water bodies.

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