Colorimetric Test Strip for Detecting Silver Ions and Mercury Ions, Preparation Method and Application Thereof

Abstract

The present invention discloses a colorimetric test strip for detecting silver ions and mercury ions, its preparation method and application. The colorimetric test strip is prepared by immersing a cellulose membrane in a 3,3’,5,5’-tetramethylbenzidine solution through an impregnation method. The colorimetric test strip in the present invention can visually detect Ag<supgt;+< / supgt> and Hg<supgt;2+< / supgt> by colorimetry, and has the advantages of simple preparation, convenient detection, sensitive response, etc. When the colorimetric test strip recognizes Ag<supgt;+< / supgt> or Hg<supgt;2+< / supgt>, the test strip gradually changes from light yellow to blue, and the visual detection limit is 1 μM. Colorimetric detection can be achieved within the concentration range of 1 μM - 100 μM. It has potential application prospects in the detection of Ag<supgt;+< / supgt> and Hg<supgt;2+< / supgt>. The colorimetric test strip of the present invention is simple to prepare, low in cost, convenient and fast to use, and has the function of early warning and semi-quantitative detection of Ag<supgt;+< / supgt> and Hg<supgt;2+< / supgt>, and has good application potential in the detection, monitoring and treatment of water environment.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical analysis and detection, and particularly to a colorimetric test paper for detecting silver ions and mercury ions, a preparation method thereof, and an application thereof. Background Art

[0002] Silver ions (Ag + ) and mercury ions (Hg 2+ ) are both highly toxic metal ions that can have adverse effects on the environment and human health. Therefore, it is of great significance to detect Ag + and Hg 2+ with high precision, practically, and conveniently.

[0003] Colorimetric detection has the advantages of being visible to the naked eye, simple to operate, low cost, and easy to read. Therefore, designing a colorimetric sensor has important value for the qualitative and semi-quantitative detection of Ag + and Hg 2+ . Summary of the Invention

[0004] The purpose of the present invention is to propose a colorimetric test paper for detecting silver ions and mercury ions, a preparation method thereof, and an application thereof, in view of the above deficiencies of the prior art.

[0005] A colorimetric test paper for detecting silver ions and mercury ions according to the present invention is prepared by immersing a cellulose membrane in a 3,3’,5,5’-tetramethylbenzidine solution by an impregnation method.

[0006] For the preparation method of the colorimetric test paper as described above, first prepare a cellulose membrane, then soak the prepared cellulose membrane in a 1 nM - 1 M TMB solution at room temperature for 0.5 - 48 hours, rinse it three times repeatedly with deionized water, and then wipe off the residual deionized water on the cellulose membrane with absorbent paper to obtain a cellulose-based colorimetric test paper for detecting silver ions and mercury ions.

[0007] Further, the preparation method of the cellulose membrane is as follows: Place the dried cotton linter in an NaOH / urea aqueous solution, quickly stir it at -12.5°C to dissolve it, and then prepare a cellulose membrane with a thickness of about 0.01 - 2 mm by a casting method. Finally, rinse the cellulose membrane with distilled water until the pH of the washing liquid is neutral to obtain a usable cellulose membrane.

[0008] For the application of the colorimetric test paper as described above, use the colorimetric test paper for the qualitative and semi-quantitative detection of Ag + or Hg 2+ .

[0009] Further, first use the colorimetric test paper to prepare known Ag + and Hg 2+Standard test paper for concentration. Then immerse the colorimetric test paper into the test solution. After reacting for a certain period of time, observe the color of the test paper. If the test paper is light yellow, it indicates that there is no Ag + and Hg 2 + in the test solution. If the test paper turns blue, it indicates that there is Ag + or Hg 2+ in the test solution. The darker the blue color, the higher the concentration of Ag + or Hg 2+ . Compare the discolored test paper with the standard test paper for known Ag + and Hg 2+ concentrations to quantitatively detect the concentration of Ag + or Hg 2+ .

[0010] Furthermore, the concentration of Ag + or Hg 2+ that can be quantitatively detected ranges from 1 μM to 100 μM.

[0011] 3,3,5,5 - Tetramethylbenzidine (TMB) is directly oxidized by Ag + / Hg 2+ to form a blue oxTMB solution, which may be caused by the redox reaction between Ag + / Hg 2+ and TMB. In order to improve the stability of TMB color development for semi - quantitative analysis, a colorimetric sensor based on high - purity cellulose membrane is designed. The highly loose network interpenetrating porous morphology of the cellulose membrane provides a large number of sites for TMB fixation. The polyhydroxy structure of the cellulose membrane forms a large number of hydrogen bonds with TMB, and the fixation of TMB is not only firm but also uniform. Therefore, the cellulose membrane is an ideal probe fixation platform, with advantages such as analyte enrichment, tight binding, uniform dispersion, and not easy to fall off. In addition, oxTMB is formed by the oxidation of uniformly fixed TMB and forms stable hydrogen bonds with the hydroxyl groups on the cellulose membrane, making the color uniform and facilitating colorimetry. The aggregated rather than dispersed oxTMB improves the visual detection limit (VDOT) of the colorimetric sensor.

[0012] The colorimetric test paper in the present invention can visually detect Ag + and Hg 2+ . It is simple to prepare and convenient to use. Compared with the detection methods that require complex instruments, it has more practical value; it has high sensitivity, low visual detection limit, good selectivity, can be reused and detected with the naked eye. The detection time is about 120 minutes. When the colorimetric test paper recognizes Ag + or Hg 2+ , the test paper gradually changes from light yellow to blue. The visual detection limit is 1 μM, and colorimetric detection can be achieved within the concentration range of 1 μM - 100 μM. In Ag +and Hg 2+ has potential application prospects in the detection. The colorimetric test strip of the present invention is simple to prepare, low in cost, convenient and fast to use, and has the functions of early warning and semi - quantitative detection of Ag + and Hg 2+ and has good application potential in the detection, monitoring and treatment of water environment. Brief Description of the Drawings

[0013] Figure 1a is the SEM / EDS diagram of the cellulose membrane;

[0014] Figure 1b is the SEM / EDS diagram of the TMB - modified cellulose membrane;

[0015] Figure 1c is the SEM / EDS diagram of the cellulose membrane after detecting silver;

[0016] Figure 1d is the SEM / EDS diagram of the cellulose membrane after detecting mercury;

[0017] Figure 2 is the colorimetric response diagram of the cellulose - based colorimetric test strip with different concentrations of Ag + (0, 1, 3, 10, 15, 20, 30, 40, 60, 80, 100 μM);

[0018] Figure 3 is the colorimetric response diagram of the cellulose - based colorimetric test strip with different concentrations of Hg 2+ (0, 1, 3, 10, 15, 20, 30, 40, 60, 80, 100 μM);

[0019] Figure 4 is the colorimetric response diagram of the colorimetric test strip with different ions (HCl, HNO 3 , Na + , Ca 2+ , Ba 2+ , Mg 2+ , Al 3+ , Cr 3+ , Co 2+ , Pb 2+ , Zn 2 + , Cu 2+ , Hg 2+ , Ag + );

[0020] Figure 5 is the recycling diagram of the colorimetric test strip;

[0021] Figure 6 is the colorimetric test strip with Ag + and Hg 2+Colorimetric response diagram. Detailed implementation mode

[0022] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0023] Example 1

[0024] A preparation method of a colorimetric test paper for detecting silver ions and mercury ions based on cellulose, specifically including the following steps:

[0025] Preparation of cellulose membrane: Place the dried cotton linters in an NaOH / urea aqueous solution, quickly stir at -12.5°C to dissolve it, and then prepare a cellulose membrane with a thickness of about 0.01 - 2 mm by a casting method. Finally, rinse the cellulose membrane with distilled water until the pH of the washing liquid is neutral to obtain a usable cellulose membrane (as Figures 1a - 1d shown, its thickness is 0.5 mm).

[0026] Preparation of cellulose membrane immobilized with TMB: Immerse the above cellulose membrane in a 1 nM - 1 M TMB solution at room temperature for 0.5 - 48 hours, repeatedly rinse it three times with deionized water, and then wipe off the residual deionized water on the cellulose membrane with paper to prepare a cellulose-based colorimetric test paper.

[0027] Its structure is characterized by SEM / EDS, as Figures 1a - 1d shown, the cellulose membrane has an interpenetrating porous morphology.

[0028] Measure the reaction effect of the colorimetric test paper obtained in Example 1 with Ag + and Hg 2+ .

[0029] Place the colorimetric test paper prepared in Example 1 in 2 mL of ultrapure water, statically incubate for 30 min as a control, and observe its color. At the same time, prepare 100 μM Ag + , Hg 2+ solutions, immerse the colorimetric test paper in Example 1 into Ag + , Hg 2+ solutions for a period of time (Ag + 55 min, Hg 2+ 70 min), observe the color change of the colorimetric test paper, as Figure 6 shown.

[0030] From Figure 2 , 3 it can be seen that the colorimetric test paper is light yellow in the absence of Ag + , Hg 2+ , and turns color in the presence of Ag + , Hg 2+The solution reacts for a period of time (Ag + 55 min, Hg 2+ 70 min). After that, the pale yellow test paper turns blue, indicating that the colorimetric test paper has a colorimetric response to Ag + , Hg 2+ .

[0031] Measure the response effect of the colorimetric test paper obtained in Example 1 with different concentrations of Ag + , Hg 2+ .

[0032] Incubate the colorimetric test paper prepared in Example 1 with different concentrations of Ag + , Hg 2+ (0, 1, 3, 10, 15, 20, 30, 40, 60, 80, 100 μM) for a period of time respectively, and observe the color change of the colorimetric test paper.

[0033] From Figure 2 , Figure 3 It can be seen that as the concentrations of Ag + , Hg 2+ increase continuously, the colorimetric test paper gradually changes from pale yellow to blue, and the color becomes darker and darker. When the concentrations of Ag + and Hg 2+ are greater than 80 μM, the color hardly changes. This indicates that the colorimetric test paper can visually detect different concentrations of Ag + and Hg 2+ .

[0034] Measure the selective detection of the colorimetric test paper obtained in Example 1 for Ag + and Hg 2+ .

[0035] Incubate the colorimetric test paper prepared in Example 1 with 14 kinds of ions with a concentration of 1 mM (HCl, HNO 3 , Na + , Ca 2+ , Ba 2+ , Mg 2+ , Al 3+ , Cr 3+ , Co 2+ , Pb 2+ , Zn 2+ , Cu 2+ , Hg 2+ , Ag + ) for 70 min in total, and compare the specific detection ability of the colorimetric test paper for Ag + and Hg 2+ , as shown in Figure 4 .

[0036] From Figure 4It can be seen that the colorimetric test strip responds best to Ag + and Hg 2+ The test strip turns into an obvious blue color, while the color of the test strip after co-incubation with other ions hardly changes, indicating that the colorimetric test strip has good selectivity for Ag + and Hg 2+ .

[0037] Determine the number of times the colorimetric test strip obtained in Example 1 can be reused.

[0038] Immerse the colorimetric test strip into the solution of Ag + and Hg 2+ , the test strip turns blue, then immerse the blue test strip into the ascorbic acid solution, and the test strip turns light yellow. Then immerse the test strip into TMB for 2 - 48 h, and repeat the cycle of immersing the test strip into the solution of Ag + and Hg 2+ , ascorbic acid solution and TMB for 6 times, and the detection ability of the test strip hardly changes, as Figure 5 shown.

[0039] From Figure 5 it can be seen that the colorimetric test strip can be reused at least 6 times, indicating that the colorimetric test strip has good reusability.

[0040] For those not covered above, the prior art shall apply.

[0041] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and not for limiting the scope of the present invention. Those skilled in the technical field to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, but will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention shall be included in the protection scope of the present invention.

Claims

1. Application of a colorimetric test strip for detecting Hg 2+ ​ It is characterized in that Use the colorimetric test strip for qualitative and semi-quantitative detection of Hg 2+ ; First, prepare a cellulose membrane, then immerse the prepared cellulose membrane in a 3,3’,5,5’-tetramethylbenzidine solution at room temperature. After rinsing it three times repeatedly with deionized water, wipe off the residual deionized water on the cellulose membrane with absorbent paper to prepare a cellulose-based colorimetric test paper for detecting Hg 2+ ; First, use the colorimetric test paper to prepare a standard test paper with a known Hg 2+ concentration. Then, immerse the colorimetric test paper in the test solution. After reacting for a certain period of time, observe the color of the test paper. If the test paper is light yellow, it indicates that there is no Hg 2+ in the test solution. If the test paper turns blue, it indicates that there is Hg 2+ in the test solution. The darker the blue color, the higher the Hg 2+ concentration. Compare the discolored test paper with the prepared standard test paper with a known Hg 2+ concentration to semi-quantitatively detect the Hg 2+ concentration.

2. The application of the colorimetric test strip according to claim 1, It is characterized in that: The preparation method of the cellulose membrane is as follows: Place the dried cotton linters in an NaOH / urea aqueous solution, quickly stir it at -12.5 °C to dissolve it, and then prepare a cellulose membrane with a thickness of about 0.01 - 2 mm by a casting method; Finally, rinse the cellulose membrane with distilled water until the pH of the washing liquid is neutral to obtain a usable cellulose membrane.

3. The application of the colorimetric test strip according to claim 1, It is characterized in that: Soak it in a 1 nM - 1 M TMB solution at room temperature for 0.5 - 48 hours.

4. The application of the colorimetric test strip according to claim 1, It is characterized in that: Can semi-quantitatively detect the concentration of Hg 2+ in the range of 1 µM - 100 µM.

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