Preparation method of MOF composite sensitive membrane for online chloride ion electrochemical sensor

Abstract

The present invention relates to a method for preparing a metal organic framework composite sensitive membrane for an online chloride ion electrochemical sensor. First, polyvinyl chloride (PVC) SG3, polyvinyl chloride (PVC) SG5, solvent tetrahydrofuran, silane coupling agent, crosslinking agent, K-MOF, and dioctyl phthalate are added to a flask in parts by weight for reaction to obtain a mixed solution S1; then tetrahydrofuran is added and the mixture is allowed to stand for 24 hours to obtain a mixed solution S2; then 2-nitrophenyl octyl ether, tetrakis(4-chlorophenyl) borate tetra(dodecyl)ammonium, and 4,5-dimethyl-3,6-dioctyloxy-o-phenylene-bis(mercuric trifluoroacetate) are added to the mixed solution S2 to obtain a mixed solution S3. Finally, the mixed solution S3 is poured into a glass sheet mold to obtain a MOF composite sensitive membrane with a thickness of 0.7 to 1 mm. The sensitive membrane prepared by the present invention has a short response time for chloride ion recognition, a simple preparation method, and is conducive to small-scale production.

Description

Technical Field

[0001] The present invention relates to the field of preparation of composite sensitive electrochemical sensors, and in particular to a method for preparing a metal organic framework (MOF) composite sensitive membrane of an online chloride ion electrochemical sensor. Background Art

[0002] Electrochemical sensors are sensor devices that perform qualitative and quantitative analysis and measurement, converting the chemical quantity of the analyte into electrical quantity for sensing and detection. Currently, PVC and plasticizers are used as the matrix of the sensor membrane in a certain ratio. The characteristics of PVC are reflected in the free volume of the chain segments and the characteristics of the chain segment motion. When the minimum free volume required for the movement of plasticizer molecules is less than the free volume of the polymer segment, the plasticizer molecules can diffuse through the polymer segment. The larger the free volume in PVC, the easier it is for the plasticizer molecules to migrate. MOF, or metal-organic framework, is a material with high specific surface area, high porosity, easily adjustable pore size, and easy functionalization. The framework structure of MOF makes it easy to prepare a uniform and dense composite membrane, effectively inhibiting the movement of the chain segments, thereby improving the performance of the membrane. In addition, the pores of MOF can also increase the mass transfer channels of the membrane, thereby increasing the flux of the membrane.

[0003] The present invention uses natural pore-forming methods to prepare a high-load, uniform, dense and stable MOF composite sensitive membrane for measuring the concentration of chloride ions. This method is green and environmentally friendly, simple and easy to use, relatively low in cost, and has good recognition effect, and has potential application value. Summary of the Invention

[0004] The present invention aims to solve the problems existing in the prior art and provides a method for preparing a metal-organic framework (MOF) composite sensitive membrane for an online chloride ion electrochemical sensor. The MOF composite sensitive membrane of the chloride ion electrochemical sensor of the present invention exhibits a good Nernst response to chloride ions.

[0005] The present invention provides a method for preparing the above-mentioned online chloride ion electrochemical sensor MOF composite sensitive membrane, comprising the following steps:

[0006] 1. Weight ratio:

[0007]

[0008]

[0009] 2. Preparation:

[0010] S1: Weigh polyvinyl chloride (PVC-SG3), polyvinyl chloride (PVC-SG5), tetrahydrofuran solvent, silane coupling agent, crosslinking agent, K-MOF, and dioctyl phthalate into a stoppered flask, heat to 75-85 degrees, and react under magnetic stirring at 30-50 rpm for 4 hours to obtain a mixed solution S1;

[0011] S2: Add an appropriate amount of tetrahydrofuran, mix well and let stand at room temperature for 24 hours to obtain a mixed solution S2.

[0012] S3: Weigh a certain amount of 2-nitrophenyl octyl ether, tetrakis(4-chlorophenyl)borate tetrakis(dodecyl)ammonium, and 4,5-dimethyl-3,6-dioctyloxy-o-phenylene-bis(trifluoroacetic mercuric acid) and add them to the mixed solution S2. Stir at a speed of 60-80 r / min and magnetically stir for 60 minutes. After stirring, let it stand at room temperature for 24 hours to obtain a mixed solution S3.

[0013] S4: The S3 mixed solution was poured into a clean glass slide mold and placed at dry room temperature for 48 hours to obtain a MOF composite sensitive membrane with a thickness of 0.7 to 1 mm.

[0014] The total amount of the polyvinyl chloride PVC-SG3 and polyvinyl chloride PVC-SG5 is 100 parts by weight.

[0015] The cross-linking agent is one of epichlorohydrin and dodecanethiol or a mixture of the two in any proportion.

[0016] The silane coupling agent is one of KH550, KH570 and KH592 or a mixture of several of them in any proportion.

[0017] The present invention has at least the following beneficial effects:

[0018] A two-dimensional conductive metal-organic framework (K-MOF) composite sensitive membrane for chloride ion electrochemical sensors is proposed, and its detection and analytical performance is demonstrated. The MOF composite sensitive membrane suitable for chloride ion electrochemical sensors prepared by the present invention has a short detection response time for chloride ions and maintains good detection performance, a good Nernst response, and long-term potential stability even when immersed in solvents. Furthermore, the present invention's preparation method is simple and has a short process flow, effectively improving production efficiency and facilitating small-scale production.

[0019] The present invention has great potential and market prospects in the fields of environmental monitoring, instant detection, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is a graph showing potential changes of a MOF composite sensitive membrane for a chloride ion electrochemical sensor according to the present invention in a solution with a chloride ion concentration of 100-3000 mg / L. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0022] The prepared ion selective electrodes were all heated for 10 -1 M KCl solution for 24 h.

[0023] Example 1

[0024] 1. Weigh 35 mg of PVC-SG5, 65 mg of PVC-SG3, 2 mg of KH570, 5 mg of epichlorohydrin, 5 mg of K-MOF, 120 mg of dioctyl phthalate, and 2 mL of tetrahydrofuran into a stoppered flask. Heat the stoppered flask to 80°C and react under magnetic stirring (speed: 30 r / min) for 4 hours to obtain a mixed solution S1.

[0025] 2. Add another 3 ml of tetrahydrofuran to the stoppered flask, seal the beaker, and let it stand at room temperature for 24 hours to obtain solution S2.

[0026] 3. Add 120 mg of 2-nitrophenyl octyl ether, 2 mg of tetrakis(4-chlorophenyl)borate tetrakis(dodecyl)ammonium, and 10 mg of 4,5-dimethyl-3,6-dioctyloxy-o-phenylene-bis(trifluoroacetic acid mercuric) to the S2 solution, and stir for 30 minutes after the addition is completed.

[0027] 4. Stop stirring and place the sample flask at room temperature for 24 hours. The solution is named Solution S3.

[0028] 5. Lay the glass sheet mold flat and adjust it to a level, pour solution S3 onto the clean glass sheet mold, and place it at dry room temperature for 48 hours to obtain an online chloride ion electrochemical sensor MOF composite sensitive membrane with a thickness of 0.5 mm.

[0029] The MOF composite sensitive membrane constructed in this example was applied to the detection of actual samples. In the range of chloride ion concentration of 50-2000 mg / L, the peak current detected had a good logarithmic linear relationship with the concentration, R = 0.9978. Figure 1 shown.

[0030] Example 2

[0031] 1. Weigh 65 mg of PVC-SG5, 35 mg of PVC-SG3, 5 mg of KH792, 5 mg of K-MOF, 10 mg of dodecanethiol, and 120 mg of dioctyl phthalate into a stoppered flask, heat the stoppered flask to 80°C, and then react under magnetic stirring at 80 r / min for 4 hours to obtain a mixed solution S1.

[0032] 2. Add another 3 ml of tetrahydrofuran to the stoppered flask, seal the beaker, and let it stand at room temperature for 24 hours to obtain solution S2.

[0033] 3. Add 120 mg of 2-nitrophenyl octyl ether, 2 mg of tetrakis(4-chlorophenyl)borate tetrakis(dodecyl)ammonium, and 10 mg of 4,5-dimethyl-3,6-dioctyloxy-o-phenylene-bis(trifluoroacetic acid mercuric) to the S2 solution, and stir for 30 minutes after the addition is completed.

[0034] 4. Stop stirring and place the sample flask at room temperature for 24 hours. The solution is named solution to obtain a mixed solution S3.

[0035] 5. Lay the glass sheet mold flat and adjust it to a level, pour solution S3 onto the clean glass sheet mold, and place it at dry room temperature for 48 hours to obtain an online chloride ion electrochemical sensor MOF composite sensitive membrane with a thickness of 0.8 mm.

Claims

1. A method for preparing an online chloride ion electrochemical sensor MOF composite sensitive membrane, characterized by: 1) Weight ratio: The total amount of polyvinyl chloride PVC-SG3 and polyvinyl chloride PVC-SG5 is 100 parts by weight; 2) Preparation: S1: Weigh polyvinyl chloride PVC-SG3, polyvinyl chloride PVC-SG5, solvent tetrahydrofuran, silane coupling agent, crosslinking agent, K-MOF, and dioctyl phthalate into a stoppered flask for reaction to obtain a mixed solution S1; S2: Add an appropriate amount of tetrahydrofuran, mix well, and let stand at room temperature for 24 hours to obtain a mixed solution S2; S3: Weigh a certain amount of 2-nitrophenyl octyl ether, tetrakis(4-chlorophenyl)borate tetrakis(dodecyl)ammonium, and 4,5-dimethyl-3,6-dioctyloxy-o-phenylene-bis(trifluoromercuric acetate) and add them to the mixed solution S2. After magnetic stirring, let it stand at room temperature for 24 hours to obtain a mixed solution S3; S4: The S3 mixed solution was poured into a clean glass slide mold and placed at dry room temperature for 48 hours to obtain a MOF composite sensitive membrane with a thickness of 0.7 to 1 mm.

2. The method for preparing an online chloride ion electrochemical sensor MOF composite sensitive membrane according to claim 1, characterized in that The reaction in step S1 is carried out by heating the temperature to 75-85° C. and then stirring the reaction under magnetic stirring at 30-50 r / min.

3. The method for preparing an online chloride ion electrochemical sensor MOF composite sensitive membrane according to claim 1, characterized in that In the step S3, magnetic stirring is performed for 60 minutes at a stirring speed of 60 to 80 r / min.

4. The method for preparing an online chloride ion electrochemical sensor MOF composite sensitive membrane according to claim 1, characterized in that The cross-linking agent is one of epichlorohydrin and dodecanethiol or a mixture of the two in any proportion.

5. The method for preparing an online chloride ion electrochemical sensor MOF composite sensitive membrane according to claim 1, characterized in that The silane coupling agent is one of KH550, KH570 and KH592 or a mixture of several of them in any proportion.

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