A green fluorescent polymer nanomaterial and its preparation method and application

Abstract

The present invention belongs to the technical field of fluorescent nanomaterials, and specifically relates to a green fluorescent polymer nanomaterial, its preparation method, and application. The present invention is the first to use polyethyleneimine and naphthaldehyde as raw materials to prepare fluorescent polymer nanomaterials GFP-NPs, which have excellent fluorescence properties and good storage stability and can emit bright green fluorescence. Due to the inner filter effect between Cr(VI) and GFP-NPs, GFP-NPs can highly selectively and sensitively detect Cr(VI) qualitatively and quantitatively, with a detection limit of 0.4μmol / L and a linear response range of 0.6-14μmol / L.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescent nanomaterials, and in particular relates to a green fluorescent polymer nanomaterial and a preparation method and application thereof. Background Art

[0002] Chromium (Cr), a common heavy metal, is crucial to the ecological environment and human health. Its valence and content affect its properties. Different oxidation states of chromium influence its biotoxicity, mobility, and other properties. For example, trace amounts of Cr(III) are essential micronutrients, playing roles in regulating blood sugar, providing antioxidant and cardiovascular protection. However, Cr(VI) is a Class I carcinogen, highly toxic and a potent oxidant. Because Cr(VI) poses significant risks to the ecological environment and human health, developing a rapid and accurate Cr(VI) detection and analysis method is crucial.

[0003] Currently, the main methods for detecting and analyzing Cr(VI) in water samples include atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry, voltammetry, ultraviolet-visible spectrophotometry, and molecular fluorescence spectrometry. Among them, inductively coupled plasma mass spectrometry (ICP-MS) has the advantages of high precision and high sensitivity, but the sample pretreatment process is cumbersome, consumables are numerous, and the instrument is expensive. Atomic spectrometry methods such as atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), and inductively coupled plasma atomic emission spectrometry (ICP-AES) also require complex sample pretreatment and cannot distinguish between chromium of different valence states. Although dibenzoyldihydrazide spectrophotometry is simple to operate, it is susceptible to interference from colored matrices. In addition, electrochemical methods are highly sensitive but require complex electrode modification, and classic voltammetry polarography even requires the use of mercury, which is harmful to the environment. Among the many methods for detecting Cr(VI), molecular fluorescence spectroscopy has good development prospects due to its advantages such as rapid operation, intuitive response, high sensitivity, and real-time monitoring. In molecular fluorescence spectroscopy, the design of fluorescent probes is crucial.

[0004] Traditional fluorescent probes face problems such as poor stability, selectivity, and sensitivity. Organic fluorescent molecular probes have poor resistance to photobleaching, and their response to Cr(VI) is often interfered with by other anions / cations, resulting in low sensitivity for Cr(VI) detection. Therefore, it is of great significance to design a fluorescent probe with good photostability, excellent selectivity, and high sensitivity. Summary of the Invention

[0005] The present invention aims to solve at least one of the problems existing in the above-mentioned prior art. To this end, the present invention provides a green fluorescent polymer nanomaterial and a preparation method and application thereof.

[0006] In order to achieve the above objectives, the specific technical solutions are as follows:

[0007] A green fluorescent polymer nanomaterial is prepared by solvent thermal reaction using polyethyleneimine (PEI) and naphthaldehyde as raw materials;

[0008] The specific preparation method comprises the following steps: dissolving PEI and naphthaldehyde in a mixed solvent of ethanol and water, carrying out a solvent thermal reaction under closed conditions, and then purifying the system after the solvent thermal reaction.

[0009] Furthermore, the mixing ratio of the PEI, naphthaldehyde, ethanol and water is (0.1-1) g: (1-20) mg: (1-9) mL: (9-1) mL.

[0010] Furthermore, the solvent thermal reaction temperature is 30-100° C., and the reaction time is 1-20 h.

[0011] The second aspect of the present invention provides a green fluorescent polymer nanomaterial prepared according to the above method. The nanomaterial is spherical, with a particle size of 2-5 nm, an optimal excitation wavelength of 380 nm, and an optimal emission wavelength of 502 nm.

[0012] The third aspect of the present invention provides an application of a green fluorescent polymer nanomaterial in the detection of Cr(VI), with a detection limit of 0.4 μmol / L and a linear response range of 0.6-14 μmol / L. The application includes the detection of Cr(VI) in electroplating plant wastewater.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] This method, for the first time, uses polyethyleneimine and naphthaldehyde as raw materials to prepare fluorescent polymer nanomaterials (GFP-NPs), which exhibit excellent fluorescence properties and good stability. Due to the inner filter effect between Cr(VI) and GFP-NPs, GFP-NPs can detect Cr(VI) with high selectivity and sensitivity for both qualitative and quantitative detection. The accuracy of this detection method is comparable to that of commonly used atomic absorption spectrometry, with a lower detection limit than that of atomic absorption spectrometry. Furthermore, compared to UV-visible absorption spectrometry, this method does not require pretreatment of the colored sample, making it simple and quick to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 HRTEM image of GFP-NPs prepared in Example 1;

[0016] Figure 2 The optimal excitation and emission spectra of GFP-NPs;

[0017] Figure 3These are pictures of GFP-NPs under visible light and 365 nm UV light;

[0018] Figure 4 (a) Fluorescence emission spectra of GFP-NPs in the presence of different concentrations of Cr(VI) (0-100 μmol / L); Figure 4 (b) is the relationship between (F0-F) / F0 and the corresponding Cr(VI) concentration (0.2-100 μmol / L); Figure 4 (c) Fluorescence emission spectra of GFP-NPs in the presence of different concentrations of Cr(VI) (0-14 μmol / L); Figure 4 (d) is the linear relationship diagram of (F0-F) / F0 and its corresponding Cr(VI) concentration;

[0019] Figure 5 This is a diagram characterizing the stability of GFP-NPs. DETAILED DESCRIPTION

[0020] The principles and features of the present invention are described below with reference to examples. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are commercially available unless otherwise specified.

[0021] Example 1

[0022] The method for preparing the green fluorescent polymer nanomaterial of this embodiment includes the following steps:

[0023] Take 1g PEI and 20mg naphthaldehyde and dissolve them in 10mL ethanol-water mixed solvent, including 5mL ethanol and 5mL water; after mixing the above solutions, perform solvent thermal reaction at 100℃ under closed conditions for 10h; after the reaction, the above-prepared material is placed in a dialysis bag and dialyzed for 24h to obtain pure fluorescent polymer nanomaterial GFP-NPs.

[0024] like Figure 1 This is the HRTEM image of the green fluorescent polymer nanomaterial prepared in this example. GFP-NPs appear as well-dispersed spherical nanoparticles with a particle size of 2-5 nm. Figure 2-3 It can be found that the optimal excitation wavelength of GFP-NPs is 380 nm, the optimal emission wavelength is 502 nm, and it emits bright green fluorescence under 365 nm ultraviolet light.

[0025] Figure 4(a) and 4(b) show the relationship between the fluorescence emission spectra of GFP-NPs in the presence of different concentrations of Cr(VI) and the concentration. It can be found that the fluorescence intensity of GFP-NPs decreases with the increase of Cr(VI) concentration (0-100 μM). Figure 4 (c) is the fluorescence emission spectrum of GFP-NPs in the range of 0-14 μM Cr(VI). Figure 4 (d) It can be seen that in the range of 0.6-14 μM, the fluorescence peak intensity of GFP-NPs has a good linear relationship with the concentration of Cr(VI), and the linear fitting curve is Y=0.03884x+0.03325(R 2 =0.9954), and the calculated detection limit of GFP-NPs for Cr(VI) was 0.4 μM.

[0026] Figure 5 This is a stability characterization diagram of the green fluorescent polymer nanomaterial prepared in this example. Figure 5 It can be seen that GFP-NPs can maintain good stability within 45 days. Its fluorescence intensity was 919 a.u. when it was first measured, and the intensity only changed by 191 a.u. after 45 days. In particular, its fluorescence intensity only decreased by 10% within 15 days.

[0027] Table 1 Determination of Cr(VI) in actual wastewater samples using the spike recovery method

[0028]

[0029] The applicability of GFP-NPs in actual sample detection was evaluated by detecting Cr(VI) in electroplating plant wastewater. As shown in Table 1, the detection RSDs of the three samples were all lower than 2%. These results indicate that the prepared GFP-NPs are expected to be used for the determination of Cr(VI) in actual samples such as electroplating plant wastewater.

[0030] Example 2

[0031] The method for preparing the green fluorescent polymer nanomaterial of this embodiment includes the following steps:

[0032] Take 0.1g PEI and 1mg naphthaldehyde and dissolve them in 10mL ethanol-water mixed solvent, including 2mL ethanol and 8mL water; after mixing the above solutions, carry out solvent thermal reaction at 80℃ under closed conditions for 14h; after the reaction, the above-prepared material is placed in a dialysis bag and dialyzed for 24h to obtain pure fluorescent polymer nanomaterial GFP-NPs.

[0033] Example 3

[0034] Take 0.5g PEI and 10mg naphthaldehyde and dissolve them in 10mL ethanol-water mixed solvent, including 4mL ethanol and 6mL water; after mixing the above solutions, perform solvent thermal reaction at 100℃ under closed conditions for 10h; after the reaction, the obtained material is placed in a dialysis bag and dialyzed for 24h to obtain pure fluorescent polymer nanomaterial GFP-NPs.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a green fluorescent polymer nanomaterial, characterized in that: It is prepared from polyethyleneimine and naphthaldehyde via solvent thermal reaction.

2. The preparation method according to claim 1, characterized in that The preparation method specifically comprises the following steps: dissolving polyethyleneimine and naphthaldehyde in a mixed solvent of ethanol and water, performing a solvent thermal reaction under closed conditions, and then purifying the system after the solvent thermal reaction.

3. The preparation method according to claim 2, characterized in that The mixing ratio of the polyethyleneimine, naphthaldehyde, ethanol and water is (0.1-1) g: (1-20) mg: (1-9) mL: (9-1) mL.

4. The preparation method according to claim 2, characterized in that The solvent thermal reaction temperature is 30-100° C., and the reaction time is 1-20 h.

5. The green fluorescent polymer nanomaterial prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The nano material is spherical, has a particle size of 2-5 nm, an optimal excitation wavelength of 380 nm, and an optimal emission wavelength of 502 nm.

6. Use of the green fluorescent polymer nanomaterial according to claim 5 in Cr(VI) detection.

7. The use according to claim 6, characterized in that The detection limit of the green fluorescent polymer nanomaterial is 0.4 μmol / L, and the linear response range is 0.6-14 μmol / L.

8. The use according to claim 6, characterized in that The application includes the detection of Cr(VI) in electroplating plant wastewater.

Images