Application of PEGDA gel microspheres in colorimetric detection of heavy metal ions in water

Abstract

This invention discloses the application of PEGDA gel microspheres in the colorimetric detection of heavy metal ions in water. The PEGDA gel microspheres are doped with a heavy metal ion indicator. The PEGDA gel microspheres provided by this invention achieve a simple, efficient, and intuitive visual detection of heavy metal ions in water by measuring the degree of color change and HSB values ​​using mobile software. (Fe-containing...) 2+ ( / Cu 2+ / Cr 6+ PEGDA gel microspheres as ion indicators for Fe in water 2+ ( / Cu 2+ / Cr 6+ The detection limit for the ion is 5 μmol / L.

Description

Technical Field

[0001] This invention belongs to the field of polymer microsphere technology, specifically relating to the application of PEGDA gel microspheres in colorimetric detection of heavy metal ions in water. Background Technology

[0002] Excessive levels of heavy metals in water bodies can cause serious harm to the natural environment and human health. For example, excessive iron (Fe) can lead to symptoms including cardiovascular failure, altered mental state, gastrointestinal bleeding, and liver and kidney failure; excessive copper (Cu) can affect human skin, bones, and teeth, leading to gastrointestinal problems, kidney failure, blood cell damage, and central nervous system depression, and is associated with diseases such as cancer and cardiovascular disease. High levels of copper can damage biological reprocessing systems in water and reduce the self-purification capacity of natural water; chromium (Cr) is a cumulative toxin and carcinogen. Frequent contact or ingestion can cause symptoms of poisoning such as abdominal discomfort or diarrhea. Once inhaled, it can irritate and corrode the respiratory tract, causing pharyngitis or bronchitis.

[0003] To avoid the harm of heavy metal ions to the environment and human health, the development of highly sensitive and reliable heavy metal ion detection technologies is of paramount importance. Furthermore, considering that multiple heavy metal ions often coexist in pollutants and interfere with each other, and that most detection methods focus on single-ion detection, there is a strong practical need for convenient and reliable simultaneous detection technologies for multiple metal ions. Currently, domestic and international technologies for heavy metal ion detection include atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry, X-ray fluorescence spectrometry, ultraviolet-visible spectrophotometry, enzyme analysis, and immunoassay. However, large-scale instrumental analysis methods are unsuitable for on-site detection due to their high cost, complexity, and expense; bioanalytical methods are limited in practical application due to the difficulty in preparing antigens and antibodies and the significant environmental influence on the results. While these methods can achieve highly sensitive detection, identification, and quantification of heavy metals, they always require well-equipped laboratories and skilled operators, and can be very expensive.

[0004] Hydrogels are polymeric materials with a three-dimensional network structure, formed by chemical bonding or physical cross-linking of high-molecular polymers, using water as the dispersion medium. Currently, there are many patent applications for the preparation methods of hydrogel materials for heavy metal ion detection. However, the raw materials or required supporting detection equipment are generally expensive, the preparation process is complex, the detection range is narrow, or it is not fast, convenient, or portable enough, which is not conducive to industrial production and further scientific research. For example, Chinese invention patent application (CN 113667144A) discloses a composite hydrogel array for visual detection of metal ions, its preparation method, and its application: a composite hydrogel is prepared by combining a sodium alginate and polyacrylamide dual-network structure hydrogel with a metal ion indicator, and the composite hydrogel array is obtained by continuously arranging them on a base. Another Chinese invention patent application (CN 109012621A) discloses a composite hydrogel fiber for heavy metal ion adsorption and detection, which is prepared by melt spinning using sodium alginate, attapulgite, and carbon quantum dots. This method requires three steps of modification to obtain the composite hydrogel, making the preparation process complex and unsuitable for industrial production. Therefore, it is of great significance to develop a reliable, rapid, simple, highly sensitive and selective analytical method. Summary of the Invention

[0005] The purpose of this invention is to provide an application of PEGDA gel microspheres in the colorimetric detection of heavy metal ions in water, enabling the detection of heavy metal ions (Fe) in water. 2+ Cu 2+ and Cr 6+ It offers simple, efficient, and intuitive visual detection.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] An application of PEGDA gel microspheres in colorimetric detection of heavy metal ions in water, wherein the PEGDA gel microspheres are doped with heavy metal ion indicators.

[0008] Furthermore, the diameter of the PEGDA gel microspheres is between 300 and 650 μm.

[0009] Furthermore, the heavy metal ion indicator is Fe. 2+ Indicator, Cu 2+ Indicator or Cr 6+ Indicator.

[0010] Furthermore, the PEGDA gel microspheres have a positive effect on Fe... 2+ Cu 2+ or Cr 6+ The detection limits were all 5 μmol / L.

[0011] Furthermore, the preparation method of the PEGDA gel microspheres includes the following steps:

[0012] (1) Prepare a dispersed phase solution including PEGDA and heavy metal ion indicator solution;

[0013] (2) Prepare an oil phase solution as a continuous phase solution;

[0014] (3) PEGDA gel microspheres were prepared by combining droplet microfluidic technology with ultraviolet curing technology.

[0015] In step (1), the heavy metal ion indicator solution is Fe 2+ Indicator solution, Cu 2+ Indicator solution or Cr 6+ Indicator solution, wherein:

[0016] Fe 2+ Indicator solution: An anhydrous ethanol solution containing 30–60 mg / mL o-phenanthroline;

[0017] Cu 2+ Indicator solution: a chloroform solution containing copper hydroxide powder at a concentration of 15–40 mg / mL;

[0018] Cr 6+ Indicator solution: 0.3-0.6g diphenylaminourea powder, 2-4mL acetone, 2-4mL deionized water and 0.1-0.3mL concentrated sulfuric acid.

[0019] Furthermore, in step (1), the PEGDA is PEG(400)DA, PEG(575)DA, PEG(600)DA or PEG(700)DA.

[0020] Step (1) specifically involves: preparing a solution containing Fe 2+ The dispersed phase solution of the indicator solution: In a brown glass bottle, add 0.3–1 mL of PEG (400, 575, 600, 700) DA, 0.05–0.2 mL of the photoinitiator 2-hydroxy-2-methyl-1-phenylpropanone, and 0.3–0.8 mL of Fe... 2+ Add indicator solution and 0.2–0.7 mL of deionized water, stir magnetically for 10–30 minutes to obtain a dispersed phase solution; prepare a Cu-containing solution. 2+ The dispersed phase solution of the indicator solution: In a brown glass bottle, add 0.3–1 mL of PEG (400, 575, 600, 700) DA, 0.05–0.2 mL of the photoinitiator 2-hydroxy-2-methyl-1-phenylpropanone, and 0.3–0.8 mL of Cu... 2+Add indicator solution and 0.5–1.5 mL of anhydrous ethanol, stir magnetically for 10–35 minutes to obtain a dispersed phase solution; prepare a Cr-containing solution. 6+ The dispersed phase solution of the indicator solution: In a brown glass bottle, add 1.1–2 mL of PEG (400, 575, 600, 700) DA, 0.1–0.5 mL of the photoinitiator 2-hydroxy-2-methyl-1-phenylpropanone, and 0.3–0.8 mL of Cr... 6+ The indicator solution is magnetically stirred for 10–30 minutes to obtain a dispersed phase solution.

[0021] Step (2) specifically involves adding oil (silicone oil, liquid paraffin, or n-hexadecane) and 1-5 wt% Span series surfactants to a beaker and stirring until completely dissolved to obtain a continuous phase solution.

[0022] Furthermore, in step (3), the continuous phase flow rate is 10–200 μL / min, the dispersed phase flow rate is 5–50 μL / min, the ratio of the dispersed phase flow rate to the continuous phase flow rate is 1:1–10, and the 365 nm ultraviolet light intensity is 30–80 mW / cm². 2 The illumination time is 1 to 15 seconds.

[0023] Step (3) specifically involves: setting up a droplet microfluidic platform, using a flow-focusing chip with a minimum channel diameter of 200–500 μm, turning on the syringe pump, and adjusting the syringe pump parameters to make the continuous phase flow rate 10–200 μL / min, the dispersed phase flow rate 5–50 μL / min, and the ratio of the dispersed phase flow rate to the continuous phase flow rate 1:1–10. After the microdroplets are stably and continuously generated, turn on the 365 nm ultraviolet lamp to make the ultraviolet light intensity received by each microdroplet 30–80 mW / cm². 2 The light exposure time is 1-15 seconds. The solidified microspheres are collected, then washed and filtered with deionized water and anhydrous ethanol. This process is repeated 3 times to obtain polyethylene glycol diacrylate (PEGDA) gel microspheres (also known as PEGDA hydrogel microspheres) doped with heavy metal ion indicators.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] The PEGDA gel microspheres for colorimetric detection of heavy metal ions in water provided by this invention are prepared using droplet microfluidic technology combined with ultraviolet bulk polymerization. Each microsphere is a detection unit, and the detection of Fe in water is achieved by measuring the degree of color change of the microsphere and the HSB value using mobile software. 2+ ( / Cu 2+ / Cr 6+ It enables simple, efficient, and intuitive visualization detection of heavy metal ions, and also allows for simultaneous multi-channel detection of the same type of ions and simultaneous multi-channel detection of different types of ions.

[0026] The PEGDA gel microsphere material provided by this invention has high utilization rate, multiple detection units, low cost, and simple operation, and can realize the visual detection of heavy metal ions anytime and anywhere. This provides a new method for the simple, efficient and intuitive detection of heavy metal ions. Attached Figure Description

[0027] Figure 1 Examples 1-3 contain Fe respectively 2+ Cu 2+ and Cr 6+ Light micrograph and particle size distribution of PEGDA gel microspheres for ion indicators (dispersed phase flow rate 30 μL / min, continuous phase flow rate 200 μL / min): (a) Fe-containing 2+ PEGDA gel microspheres of ion indicators, (b) Cu-containing 2+ PEGDA gel microspheres of ion indicators, (c) containing Cr 6+ PEGDA gel microspheres for ion indicators.

[0028] Figure 2 The dispersed phase flow rate and Fe content in Examples 1-3 2+ Cu 2+ Cr 6+ Size relationship of PEGDA gel microspheres for ion indicators (continuous phase flow rate 200 μL / min).

[0029] Figure 3 For the Fe-containing examples 1-3 2+ Cu 2+ and Cr 6+ PEGDA gel microspheres of ion indicators were used to detect Fe content. 2 + Cu 2+ and Cr 6+ SEM images ((a), (b), (c)) and EDS images ((d), (e), (f)) after ionization solution.

[0030] Figure 4 Colorimetric analysis of PEGDA gel microspheres showed different concentrations of heavy metal ions: (a) Fe 2+ (b)Cu 2+ and (c)Cr 6+ .

[0031] Figure 5 The graph shows the relationship between the measured HSB values ​​of PEGDA gel microspheres and the concentration of each heavy metal ion: (a) Fe 2+ (b)Cu 2+ and (c)Cr 6+ .

[0032] Figure 6 Colorimetric analysis of PEGDA thin films revealed different concentrations of heavy metal ions: (d)Fe 2+ (e)Cu 2+ and (f)Cr 6 + . Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to embodiments and accompanying drawings. It should be noted that the following embodiments are merely for explanation and illustration and are not intended to limit the invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description are still within the scope of protection of this invention.

[0034] The method for applying PEGDA gel microspheres doped with heavy metal ion indicators to the colorimetric detection of heavy metal ions in water provided by this invention is as follows:

[0035] A uniform layer of PEGDA gel microspheres was deposited in each cylindrical recess of the mold. As a comparative example, the above-described dispersed phase solution was dropped into each cylindrical recess, and then tested under a 365 nm UV lamp with an UV intensity of 30–80 mW / cm². 2 The illumination time was 1–15 s, and a polyethylene glycol diacrylate (PEGDA) hydrogel film containing heavy metal ion indicators was obtained.

[0036] Prepare Fe-containing solutions with concentrations of 0, 5, 10, 15, 20, 40, 80, 100, 300, and 500 μmol / L. 2+ (FeCl2){ / Cu 2+ (CuSO4) / Cr 6+ The test solution containing (K2Cr2O7) was then drawn up with a pipette, and the Fe content was then drawn up. 2+ (FeCl2){ / Cu 2+ (CuSO4) / Cr 6+ One drop of the (K2Cr2O7) solution was dropped into each cylindrical indentation in the mold. After a few seconds, the solution containing Fe was tested. 2+ ( / Cu 2+ / Cr 6+ The polyethylene glycol diacrylate (PEGDA) hydrogel microspheres and films of heavy metal ion indicators change from colorless to red (yellow / purple), and then their HSB values ​​are measured by the degree of color change of the microspheres and films and mobile phone software.

[0037] Example 1

[0038] This embodiment utilizes droplet microfluidics technology to prepare a colorimetric method for detecting Fe in water. 2+ The detailed process of PEGDA gel microspheres containing heavy metal ions is as follows:

[0039] (1) Preparation of dispersed phase solution: Preparation of Fe 2+ For the indicator solution, add 0.3g of white o-phenanthroline powder and 6mL of anhydrous ethanol to a glass bottle, and stir magnetically for 10 minutes until the solution is clear. Then, add 0.5mL of PEG(400)DA, 0.1mL of the photoinitiator 2-hydroxy-2-methyl-1-phenylpropanone, and 0.5mL of Fe to a brown glass bottle in sequence. 2+ The indicator solution and 0.5 mL of deionized water were magnetically stirred for 10 minutes to obtain the dispersed phase solution.

[0040] (2) Preparation of continuous phase solution: Add liquid paraffin and 2wt% Span80 surfactant to a beaker and stir until completely dissolved to obtain continuous phase solution.

[0041] (3) Preparation of PEGDA gel microspheres using droplet microfluidic technology combined with UV curing technology: A droplet microfluidic platform was constructed using a flow-focusing chip with a minimum channel diameter of 200 μm. The syringe pump was turned on, and the pump parameters were adjusted to achieve a continuous phase flow rate of 200 μL / min and a dispersed phase flow rate of 30 μL / min. After the microdroplets were stably and continuously generated, a 365 nm UV lamp was turned on to ensure that the UV light intensity received by each microdroplet was 30 mW / cm². 2 The light exposure time was 5 seconds, and the solidified microspheres were collected. They were then washed and filtered with deionized water and anhydrous ethanol, and this process was repeated three times to obtain Fe-doped microspheres. 2+ Polyethylene glycol diacrylate (PEGDA) hydrogel microspheres as heavy metal ion indicators.

[0042] The Fe-doped material prepared in this embodiment 2+ A layer of polyethylene glycol diacrylate (PEGDA) hydrogel microspheres for heavy metal ion indicators is uniformly deposited on a substrate such as... Figure 4 In each cylindrical recess of the mold shown in (a). For comparison, as Figure 6 The above dispersed phase solution was dropped into each cylindrical pit of the mold shown in (d), and then subjected to ultraviolet light at a UV intensity of 30 mW / cm² at 365 nm. 2 The illumination time was 5 seconds, and Fe-doped products were obtained. 2+ A polyethylene glycol diacrylate (PEGDA) hydrogel film for heavy metal ion indicators. Then, Fe-containing hydrogels were prepared at concentrations of 0, 5, 10, 15, 20, 40, 80, 100, 300, and 500 μmol / L. 2+ The test solution containing (FeCl2) was then drawn up using a pipette.2+ One drop of the (FeCl2) test solution was added to each cylindrical indentation in the mold. After a few seconds, the solution containing Fe... 2+ The polyethylene glycol diacrylate (PEGDA) hydrogel microspheres and films of heavy metal ion indicators change from colorless to red, and then their HSB values ​​are measured by the degree of color change of the microspheres and films and by mobile phone software.

[0043] The obtained Fe-doped 2+ Optical micrographs and particle size distributions of polyethylene glycol diacrylate (PEGDA) hydrogel microspheres for heavy metal ion indicators are shown below. Figure 1 As shown in (a), the dispersed phase flow rate and the Fe content 2+ Size distribution of PEGDA gel microspheres for ion indicators (continuous phase flow rate 200 μL / min) is shown below. Figure 2 As shown, the Fe-doped sample after testing... 2+ Scanning electron microscopy (SEM) image of polyethylene glycol diacrylate (PEGDA) hydrogel microspheres for heavy metal ion indicators, as shown below. Figure 3 As shown in (a) above, the energy dispersive spectroscopy (EDS) plot is as follows: Figure 3 As shown in (d), it is doped with Fe. 2+ Colorimetric analysis of PEGDA gel microspheres as heavy metal ion indicators showed different concentrations of Fe. 2+ Heavy metal ions such as Figure 4 As shown in (a), based on the measured Fe-doped... 2+ The color HSB value of PEGDA gel microspheres for heavy metal ion indicators and Fe 2+ The relationship between heavy metal ion concentrations is shown in the graph below. Figure 5 As shown in (a), it is doped with Fe 2+ Colorimetric analysis of PEGDA thin film of heavy metal ion indicator showed different concentrations of Fe. 2+ Heavy metal ions such as Figure 6 As shown in (d) in the figure.

[0044] The Fe-doped material prepared in this embodiment has approximately 95% Fe content. 2+ The polyethylene glycol diacrylate (PEGDA) hydrogel microspheres of the heavy metal ion indicator have a particle size of 365–405 μm. When the dispersed phase flow rate varies from 5–50 μL / min (continuous phase flow rate is 200 μL / min), the microsphere particle size is 60–650 μm. Fe is also present. 2+ PEGDA film for heavy metal ion indicators containing Fe 2+ The detection limit for the (FeCl2) test solution is 80 μmol / L. In comparison, the detection limit for Fe-doped solutions is much higher. 2+ PEGDA gel microspheres for heavy metal ion indicators containing Fe 2+The detection limit for the (FeCl2) test solution is 5 μmol / L. As the Fe content... 2+ As the concentration of the (FeCl2) test solution increases, the color of the microspheres becomes increasingly red.

[0045] Example 2

[0046] This embodiment utilizes droplet microfluidics technology to prepare a colorimetric method for detecting Cu in water. 2+ The detailed process of PEGDA gel microspheres containing heavy metal ions is as follows:

[0047] (1) Preparation of dispersed phase solution: Preparation of Cu 2+ For the indicator solution, add 0.15g of copper hydroxide powder and 6mL of chloroform to a glass bottle, and stir magnetically for 20 minutes until the solution is clear. Then, add 0.5mL of PEG(400)DA, 0.1mL of the photoinitiator 2-hydroxy-2-methyl-1-phenylpropanone, and 0.5mL of Cu to a brown glass bottle in sequence. 2+ The indicator solution and 0.5 mL of anhydrous ethanol were magnetically stirred for 15 minutes to obtain the dispersed phase solution.

[0048] (2) Preparation of continuous phase solution: Add liquid paraffin and 2wt% Span80 surfactant to a beaker and stir until completely dissolved to obtain continuous phase solution.

[0049] (3) Preparation of PEGDA gel microspheres using droplet microfluidic technology combined with UV curing technology: A droplet microfluidic platform was constructed using a flow-focusing chip with a minimum channel diameter of 200 μm. The syringe pump was turned on, and the pump parameters were adjusted to achieve a continuous phase flow rate of 200 μL / min and a dispersed phase flow rate of 30 μL / min. After the microdroplets were stably and continuously generated, a 365 nm UV lamp was turned on to ensure that the UV light intensity received by each microdroplet was 30 mW / cm². 2 The light exposure time was 5 seconds, and the solidified microspheres were collected. They were then washed and filtered with deionized water and anhydrous ethanol, and this process was repeated three times to obtain Cu-doped microspheres. 2+ Polyethylene glycol diacrylate (PEGDA) hydrogel microspheres as heavy metal ion indicators.

[0050] The Cu-doped material prepared in this embodiment 2+ A layer of polyethylene glycol diacrylate (PEGDA) hydrogel microspheres for heavy metal ion indicators is uniformly deposited on a substrate such as... Figure 4 In each cylindrical recess of the mold shown in (b). For comparison, as Figure 6 The above dispersed phase solution was dropped into each cylindrical pit of the mold shown in (e), and then subjected to ultraviolet light at a UV intensity of 30 mW / cm² at 365 nm. 2 The illumination time was 5 seconds, and Cu-doped samples were obtained. 2+A polyethylene glycol diacrylate (PEGDA) hydrogel film for heavy metal ion indicators. Then, Cu-containing solutions with concentrations of 0, 5, 10, 15, 20, 40, 80, 100, 300, and 500 μmol / L were prepared. 2+ The test solution of (CuSO4) was then drawn up with a pipette. 2+ One drop of the (CuSO4) test solution was dropped into each cylindrical pit in the mold. After a few seconds, the solution containing Cu... 2+ The polyethylene glycol diacrylate (PEGDA) hydrogel microspheres and films of heavy metal ion indicators change from colorless to yellow. The HSB value is then measured by the degree of color change of the microspheres and films and by mobile phone software.

[0051] The obtained Cu-doped 2+ Optical micrographs and particle size distributions of polyethylene glycol diacrylate (PEGDA) hydrogel microspheres for heavy metal ion indicators are shown below. Figure 1 As shown in (b), the dispersed phase flow rate and Cu content 2+ Size distribution of PEGDA gel microspheres for ion indicators (continuous phase flow rate 200 μL / min) is shown below. Figure 2 As shown, the Cu-doped sample after testing... 2+ Scanning electron microscopy (SEM) image of polyethylene glycol diacrylate (PEGDA) hydrogel microspheres for heavy metal ion indicators, as shown below. Figure 3 As shown in (b) above, the energy dispersive spectroscopy (EDS) plot is as follows: Figure 3 As shown in (e), it is doped with Cu 2+ Colorimetric analysis of PEGDA gel microspheres as heavy metal ion indicators showed different concentrations of Cu. 2+ Heavy metal ions such as Figure 4 As shown in (b), based on the measured Cu-doped... 2+ The color HSB value of PEGDA gel microspheres for heavy metal ion indicators and Cu 2+ The relationship between heavy metal ion concentrations is shown in the graph below. Figure 5 As shown in (b), it is doped with Cu 2+ Colorimetric analysis of PEGDA thin film of heavy metal ion indicator showed different concentrations of Cu 2+ Heavy metal ions such as Figure 6 As shown in (e) in the diagram.

[0052] The Cu-doped material prepared in this embodiment has a content of approximately 90%. 2+ The polyethylene glycol diacrylate (PEGDA) hydrogel microspheres of the heavy metal ion indicator have a particle size of 340–400 μm. When the dispersed phase flow rate varies from 5–50 μL / min (continuous phase flow rate is 200 μL / min), the microsphere particle size is 70–650 μm. Cu is also present. 2+PEGDA film for heavy metal ion indicators containing Cu 2+ The detection limit for the (CuSO4) test solution is 15 μmol / L, compared to that for Cu-doped solutions. 2+ PEGDA gel microspheres for heavy metal ion indicators containing Cu 2+ The detection limit for the (CuSO4) test solution is 5 μmol / L, and it decreases with increasing Cu content. 2+ As the concentration of the (CuSO4) test solution increases, the color of the microspheres becomes increasingly yellow.

[0053] Example 3

[0054] This embodiment utilizes droplet microfluidics technology to prepare a colorimetric assay for detecting Cr in water. 6+ The detailed process of PEGDA gel microspheres containing heavy metal ions is as follows:

[0055] (1) Preparation of dispersed phase solution: Preparation of Cr 6+ For the indicator solution, add 0.36g of diphenylaminourea powder, 3mL of acetone, 3mL of deionized water, and 0.2mL of concentrated sulfuric acid to a glass bottle, and stir magnetically for 30 minutes until the solution is clear. Then, add 1.5mL of PEG(400)DA, 0.3mL of the photoinitiator 2-hydroxy-2-methyl-1-phenylpropanone, and 0.5mL of Cr to a brown glass bottle. 6+ The indicator solution was magnetically stirred for 10 minutes to obtain a dispersed phase solution.

[0056] (2) Preparation of continuous phase solution: Add liquid paraffin and 2wt% Span80 surfactant to a beaker and stir until completely dissolved to obtain continuous phase solution.

[0057] (3) Preparation of PEGDA gel microspheres using droplet microfluidic technology combined with UV curing technology: A droplet microfluidic platform was constructed using a flow-focusing chip with a minimum channel diameter of 200 μm. The syringe pump was turned on, and the pump parameters were adjusted to achieve a continuous phase flow rate of 200 μL / min and a dispersed phase flow rate of 30 μL / min. After the microdroplets were stably and continuously generated, a 365 nm UV lamp was turned on to ensure that the UV light intensity received by each microdroplet was 30 mW / cm². 2 The light exposure time was 2 seconds, and the solidified microspheres were collected. They were then washed and filtered with deionized water and anhydrous ethanol, and this process was repeated three times to obtain Cr-doped microspheres. 6+ Polyethylene glycol diacrylate (PEGDA) hydrogel microspheres as heavy metal ion indicators.

[0058] The Cr-doped material prepared in this embodiment 6+ A layer of polyethylene glycol diacrylate (PEGDA) hydrogel microspheres for heavy metal ion indicators is uniformly deposited on a substrate such as... Figure 4In each cylindrical recess of the mold shown in (c). For comparison, as... Figure 6 The above dispersed phase solution was dropped into each cylindrical pit of the mold shown in (f), and then subjected to ultraviolet light at a UV intensity of 30 mW / cm² at 365 nm. 2 The illumination time was 2 seconds, and Cr-doped products were obtained. 6+ A polyethylene glycol diacrylate (PEGDA) hydrogel film for heavy metal ion indicators. Then, Cr-containing hydrogels with concentrations of 0, 5, 10, 15, 20, 40, 80, 100, 300, and 500 μmol / L were prepared. 6+ The test solution of (K2Cr2O7) was then used to draw up the Cr-containing solution. 6+ One drop of the (K2Cr2O7) test solution was dropped into each cylindrical indentation in the mold. After a few seconds, the solution containing Cr... 6+ The polyethylene glycol diacrylate (PEGDA) hydrogel microspheres and films of heavy metal ion indicators change from colorless to purple. The HSB value is then measured by the degree of color change of the microspheres and films and by mobile phone software.

[0059] The obtained Cr-doped 6+ Optical micrographs and particle size distributions of polyethylene glycol diacrylate (PEGDA) hydrogel microspheres for heavy metal ion indicators are shown below. Figure 1 As shown in (c), the dispersed phase flow rate and the Cr content 6+ Size distribution of PEGDA gel microspheres for ion indicators (continuous phase flow rate 200 μL / min) is shown below. Figure 2 As shown, the Cr-doped sample after testing... 6+ Scanning electron microscopy (SEM) image of polyethylene glycol diacrylate (PEGDA) hydrogel microspheres for heavy metal ion indicators, as shown below. Figure 3 As shown in (c) above, the energy dispersive spectroscopy (EDS) plot is as follows: Figure 3 As shown in (f), it is doped with Cr 6+ Colorimetric analysis of PEGDA gel microspheres as heavy metal ion indicators showed different concentrations of Cr. 6+ Heavy metal ions such as Figure 4 As shown in (c), based on the measured Cr doping... 6+ The color HSB value of PEGDA gel microspheres for heavy metal ion indicators and Cr 6+ The relationship between heavy metal ion concentrations is shown in the graph below. Figure 5 As shown in (c), it is doped with Cr 6+ Colorimetric analysis of PEGDA thin film of heavy metal ion indicator showed different concentrations of Cr 6+ Heavy metal ions such as Figure 6 As shown in (f) in the figure.

[0060] The Cr-doped material prepared in this embodiment contains approximately 90% Cr.6+ The polyethylene glycol diacrylate (PEGDA) hydrogel microspheres of the heavy metal ion indicator have a particle size of 360–400 μm. When the dispersed phase flow rate varies from 5–50 μL / min (continuous phase flow rate is 200 μL / min), the microsphere particle size is 75–650 μm. Cr is also present. 6+ PEGDA film for heavy metal ion indicators containing Cr 6+ The detection limit for the (K2Cr2O7) test solution is 15 μmol / L. In contrast, the detection limit for Cr-doped solutions is much higher. 6+ PEGDA gel microspheres for heavy metal ion indicators containing Cr 6+ The detection limit for the (K2Cr2O7) test solution is 5 μmol / L, and it decreases with increasing Cr content. 6+ As the concentration of the (K2Cr2O7) test solution increases, the color of the microspheres becomes increasingly purple.

[0061] In summary, the Fe-containing [material] provided by the present invention 2+ ( / Cu 2+ / Cr 6+ PEGDA gel microspheres as ion indicators for Fe in water 2+ ( / Cu 2+ / Cr 6+ The detection limit for Fe ions is 5 μmol / L (5 μmol / L / 5 μmol / L), while the detection limit for Fe ions is 5 μmol / L (5 μmol / L / 5 μmol / L). 2+ ( / Cu 2+ / Cr 6+ PEGDA film of ion indicator for Fe in water 2+ ( / Cu 2+ / Cr 6+ The detection limit for ions is 80 μmol / L ( / 15 μmol / L / 15 μmol / L). Due to the uniform size and small diameter of the microspheres, their spherical structure amplifies the color. Compared with the film, the gel microspheres exhibit better detection performance and can improve the detection signal of heavy metal ions.

Claims

1. An application of PEGDA gel microspheres in the colorimetric detection of heavy metal ions in water, characterized in that, The PEGDA gel microspheres are doped with heavy metal ion indicators; The preparation method of the PEGDA gel microspheres includes the following steps: (1) Prepare a dispersed phase solution including PEGDA and heavy metal ion indicator solution; (2) Prepare an oil phase solution as a continuous phase solution; (3) PEGDA gel microspheres were prepared by combining droplet microfluidic technology with ultraviolet curing technology; The heavy metal ion indicator solution is Fe 2+ Indicator solution, Cu 2+ Indicator solution or Cr 6+ Indicator solution, wherein: Fe 2+ Indicator solution: Anhydrous ethanol solution containing 30~60 mg / mL o-phenanthroline; Cu 2+ Indicator solution: a chloroform solution containing copper hydroxide powder at a concentration of 15~40 mg / mL; Cr 6+ Indicator solution: 0.3~0.6g diphenylaminourea powder, 2~4mL acetone, 2~4mL deionized water and 0.1~0.3mL concentrated sulfuric acid.

2. The application according to claim 1, characterized in that, The diameter of the PEGDA gel microspheres is 300~650 μm.

3. The application according to claim 1, characterized in that, PEGDA gel microspheres for Fe 2+ Cu 2+ or Cr 6+ The detection limits were all 5 μmol / L.

4. The application according to claim 1, characterized in that, In step (1), the PEGDA is PEGDA-400, PEGDA-575, PEGDA-600 or PEGDA-700.

5. The application according to claim 1, characterized in that, In step (3), the droplet microfluidic technology combined with UV curing technology has the following flow rates: continuous phase solution flow rate is 10-200 μL / min, dispersed phase solution flow rate is 5-50 μL / min, the ratio of dispersed phase solution flow rate to continuous phase solution flow rate is 1:1-10, and 365nm UV light intensity is 30-80 mW / cm². 2 The illumination time is 1~15 s.

6. The application according to any one of claims 1-5, characterized in that, The PEGDA gel microspheres enable the visual detection of heavy metal ions in water by measuring the degree of color change and HSB value using mobile software.

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