Preparation method and application of RE-MOF-coated C60 / beta-CD / GCE electrode for detecting dichlorophenol in water body

Abstract

The invention belongs to the technical field of electrochemical analysis, discloses a preparation method and application of an RE-MOF-coated C60 / beta-CD / GCE electrode for detecting dichlorophenol in a water body, and particularly relates to an electrochemical sensor based on a rare earth metal organic framework, fullerene and water-soluble beta-cyclodextrin ternary nano composite material, which is used for detecting 2, 4-dichlorophenol in the water body. And 2, 2-methylenebis (4-chlorophenol) is obtained. The electrical conductivity of the composite material is remarkably improved by embedding RE-MOF into C60, then RE-MOF is compounded with beta-CD, and the electro-catalytic oxidation activity of Dcp is remarkably enhanced by utilizing the subject-object recognition effect of RE-MOF and beta-CD. The prepared electrode has low detection limit and good reproducibility, stability and selectivity, is successfully applied to detection of Dcp in an actual water sample, and shows good recovery rate. The electrode has the advantages of simplicity, convenience, low cost, high efficiency and high sensitivity.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical analysis and relates to a RE-MOF@C for detecting dichlorophenol in water. 60 Preparation method and application of / β-CD / GCE electrode. Background Art

[0002] 2,2-methylenebis(4-chlorophenol) (dichlorophenol, Dcp) is a highly toxic environmental pollutant. Its concentration in the environment is low and it is stable and not easily degraded. Its efficient detection has become a hot topic in current research. Traditional methods include high performance liquid chromatography, gas chromatography, capillary electrophoresis, solid phase microextraction and flow injection analysis, etc., which have the disadvantages of high detection costs, time consumption and complicated sample processing procedures. Based on this, the present invention has developed a method based on rare earth metal organic framework (RE-MOF), fullerene (C 60 ) and water-soluble β-cyclodextrin (β-CD) ternary nanocomposite electrochemical sensor, which was used to detect dichlorophenol in water. 60 The conductivity of the composite material can be significantly improved, thereby enhancing the electrocatalytic performance of the material. Further compounding β-CD, thanks to the host-guest recognition effect of βCD, RE-MOF@C 60 The / β-CD modified electrode showed excellent electrocatalytic activity for Dcp oxidation. The developed sensor achieved a low detection limit for sensitive detection of Dcp. In addition, the sensor also had good reproducibility, stability and selectivity. The sensor has been successfully applied to the detection of Dcp in actual water samples with a good recovery rate. The sensor proposed in the present invention has the advantages of simplicity, low cost, high efficiency, high sensitivity and high specificity, and provides an important basis for the specific identification and high-selective detection of dichlorophen in actual water samples. Summary of the invention

[0003] In view of the technical problems of low sensitivity and poor detection limit in the prior art, the present invention provides a novel method based on rare earth metal organic framework (RE-MOF), fullerene (C 60 ), an electrochemical sensor based on a β-cyclodextrin (β-CD) composite material, which has the advantages of low cost, simple preparation, sensitivity, rapidity, and good selectivity, and can realize rapid and sensitive detection of dichlorophenol in water.

[0004] The technical solution of the present invention:

[0005] An electrochemical sensor for the detection of dichlorophenol in water is composed of RE-MOF@C 60 The glassy carbon electrode modified with the β-CD composite material is used as the working electrode and the three-electrode system including the counter electrode and the reference electrode is used to form an electrochemical sensor for detecting dichlorophenol with the electrochemical workstation.Figure 1 The sensor device of the present invention is schematically shown in FIG. The preparation of the sensor and its application in dichlorophenol in water include the following steps:

[0006] (1)RE-MOF@C 60 Preparation of / β-CD composite materials: rare earth metal salt and organic ligand are ultrasonically dissolved in organic solvents to obtain two solutions; 60 , β-CD and the two solutions were mixed and magnetically stirred; after reacting for a certain time under certain temperature conditions, the reaction was cooled, the product was centrifuged and washed to obtain a precipitate, and then dried to obtain RE-MOF@C 60 / β-CD composites;

[0007] (2) Preparation of electrochemical sensor: RE-MOF@C 60 The / β-CD composite material is ultrasonically dispersed uniformly with an organic solvent to obtain a dispersion; before modifying the glassy carbon electrode, the glassy carbon electrode is polished with alumina powders with a particle size of 1.0 μm and 0.05 μm, respectively, and then ultrasonically cleaned in water, ethanol and water in turn; the dispersion is droplet-coated on the polished surface of the glassy carbon electrode and dried to obtain RE-MOF@C 60 / β-CD / GCE electrode. RE-MOF / GCE, β-CD / GCE, and C 60 / GCE and RE-MOF@C 60 / GCE.

[0008] Electrochemical detection of dichlorophenol: the working electrode RE-MOF@C 60 / β-CD / GCE, counter electrode and reference electrode are connected to the electrochemical workstation to assemble into an electrochemical sensor, and electrochemical technology is used to perform electrochemical detection of dichlorophenol in water. The electrochemical workstation records the current-voltage changes, obtains the current-voltage curve, reads the current values ​​corresponding to different dichlorophenol concentrations, and draws the current-concentration linear working curve.

[0009] Preferably, the rare earth metal salt described in step (1) includes, but is not limited to, one or a mixture of two or more of rare earth metal nitrates or rare earth metal chlorides.

[0010] Preferably, the organic ligand described in step (1) includes, but is not limited to, one or a mixture of two or more of dimethylimidazole, terephthalic acid, aminoterephthalic acid, and dihydroxyterephthalic acid.

[0011] Preferably, the organic solvent described in steps (1) and (2) includes but is not limited to one or a mixture of two or more of methanol, ethanol, acetonitrile, dichloromethane, dimethyl sulfoxide, toluene, acetone, tetrahydrofuran, isopropanol, n-butanol, and N,N-dimethylformamide (DMF).

[0012] Preferably, the magnetic stirring time in step (1) is 0.1 to 96 hours.

[0013] Preferably, in step (1), the certain temperature is 60 to 250° C., and the certain time is 0.5 to 96 hours.

[0014] The reference electrode includes but is not limited to an Ag / AgCl electrode, a saturated calomel electrode and a mercury-mercurous sulfate electrode.

[0015] Preferably, the counter electrode includes but is not limited to a platinum wire or platinum sheet electrode.

[0016] Preferably, the electrochemical technique includes, but is not limited to, cyclic voltammetry, differential pulse voltammetry, square wave voltammetry and linear sweep voltammetry.

[0017] Preferably, the water body includes but is not limited to river water, lake water, well water and tap water.

[0018] Beneficial effects of the invention: The invention overcomes the shortcomings of the traditional detection method, such as cumbersome and time-consuming, high cost and complicated sample processing. 60 The novel electrochemical sensor based on / β-CD composite material was successfully used to detect Dcp in water. The nanocomposite material combines the host-guest recognition performance of β-CD with the excellent electrocatalytic activity and C 60 The synergistic effect makes the sensor fast, sensitive and selective for Dcp detection, with a wide detection range and a low detection limit. In addition, when detecting Dcp in actual water samples including tap water and lake water, a satisfactory recovery rate was achieved, indicating the good applicability of the assay. The present invention provides a new method for detecting Dcp and can be used as a potential method for monitoring other environmental pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Based on RE-MOF@C 60 Schematic diagram of the preparation and detection of / β-CD composite electrochemical sensor.

[0020] Figure 2 The material results of the method of Example 1 are shown in Figure 1, where (A) is La-MOF@C 60 X-ray photoelectron spectroscopy (XPS) diagram of C / β-CD material, (B) 60 , La-MOF, β-CD and La-MOF@C 60 / β-CD infrared spectrum (FT-IR).

[0021] Figure 3The bare glassy carbon electrode (GCE), β-CD / GCE, and C 60 / GCE, La-MOF / GCE and La-MOF@C 60 Cyclic voltammetry (CV) curve of / β-CD / GCE.

[0022] Figure 4 The results of the electrochemical sensor prepared by the method of Example 1 detecting dichlorophenol standard solutions of different concentrations in tap water are shown in Figure 1, wherein (A) is a differential pulse voltammetry (DPV) curve and (B) is a current-concentration linear fitting working curve.

[0023] Figure 5 1 is the test result of the electrochemical sensor prepared by the method of Example 1, wherein (A) is a reproducibility test graph, and (B) is a selectivity test bar graph.

[0024] Figure 6 The results of the electrochemical sensor prepared by the method of Example 2 detecting dichlorophenol standard solutions of different concentrations in lake water are shown in Figure 2, wherein (A) is a differential pulse voltammetry (DPV) curve and (B) is a current-concentration linear fitting working curve. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0026] Example 1

[0027] A La-MOF@C 60 The / β-CD / GCE sensor is used to detect dichlorophenol in tap water, including the following steps:

[0028] 0.93 g of rare earth metal salt lanthanum nitrate and 1.55 g of organic ligand dimethylimidazole were ultrasonically dissolved in 10 mL of methanol. 60 The above two solutions were mixed with 0.01 g β-CD and stirred with magnetic force for 30 minutes. Then it was transferred to a 25 mL reactor and placed in a 150 ° C oven for 12 hours. After cooling, the product was centrifuged and washed with anhydrous ethanol three times, and then dried in an oven at 80 ° C for 12 hours to obtain La-MOF@C 60 / β-CD composite materials.

[0029] Figure 2 A is La-MOF@C prepared by the method of Example 1 60 The XPS measurement spectrum of the / β-CD composite material contains characteristic peaks of C, N, O and La elements, indicating the successful synthesis of the composite material.

[0030] Figure 2B is C prepared by the method of Example 1 60 , La-MOF, β-CD and La-MOF@C 60 FT-IR of / β-CD, composite La-MOF@C 60 The infrared spectrum of / β-CD contains a single C 60 , La-MOF, and β-CD materials, indicating the successful synthesis of the composite material.

[0031] Weigh the La-MOF@C prepared by the method of Example 1 60 The / β-CD composite material was ultrasonically dispersed evenly with DMF to obtain a dispersion. Before modifying the electrode, the glassy carbon electrode was polished with 1.0μm and 0.05μm alumina powders, respectively, and then ultrasonically cleaned in water, ethanol and water in turn. The material dispersion was droplet-coated on the polished glassy carbon electrode surface and dried to obtain La-MOF@C 60 / β-CD / GCE. La-MOF / GCE, β-CD / GCE, and C 60 / GCE and La-MOF@C 60 / GCE.

[0032] The working electrode La-MOF@C prepared by the method of Example 1 was 60 / β-CD / GCE, a counter electrode platinum wire and an Ag / AgCl reference electrode were connected to an electrochemical workstation and assembled into an electrochemical sensor.

[0033] The cyclic voltammetry (CV) was used to investigate the relationship between the bare glassy carbon electrode (GCE), β-CD / GCE, and C 60 / GCE, La-MOF / GCE and La-MOF@C 60 / β-CD / GCE electrocatalytic effect on dichlorophenol in water. Figure 3 As shown in the figure, compared with other materials modified electrodes, La-MOF@C 60 / β-CD / GCE has the largest CV peak current and the best effect.

[0034] Figure 4 A, the DPV curve of the electrochemical sensor prepared by the method of Example 1 detecting different dichlorophenol concentrations in tap water is recorded by an electrochemical workstation, and the current values ​​corresponding to different dichlorophenol concentrations are read and plotted as follows: Figure 4 The current-concentration linear fitting working curve in B shows that the linear detection range is 0.03 μM-25 μM, and the detection limit is 11.6 nM.

[0035] Figure 5 La-MOF@C prepared by the method of Example 1 60 / β-CD / GCE for the detection of dichlorophenol reproducibility (A) and selectivity (B). Ten parallel modified electrodes were used to detect 10 μM dichlorophenol. Figure 5 A shows that the relative standard deviation (RSD) of the DPV response current value is 3.49%, indicating that the sensor has good reproducibility. In addition, in order to evaluate the selectivity of the sensor, 10 μM Dcp was detected in tap water with interferences such as structural analogs and inorganic ions. The concentrations of hydroquinone (HQ), 4-aminophenol (p-NP), resorcinol (RC), Na + NH4 + , K + Mg 2+ , Cl - 、SO4 2- , and PO4 3- The DPV current of dichlorophenol (Dcp) was affected and it was found that all signals could be maintained above 90% after adding interfering substances, indicating that La-MOF@C 60 / β-CD sensor has good selectivity.

[0036] The recovery rate of the sensor in tap water is shown in Table 1. The recovery rate is between 96.6% and 102.6%, indicating that the sensor has good applicability in tap water.

[0037] Table 1 Recovery rate measurement of dichlorophenol in tap water samples

[0038]

[0039] Example 2

[0040] A La-MOF@C 60 The / β-CD / GCE sensor is used to detect dichlorophenol in lake water, including the following steps:

[0041] 0.93 g of rare earth metal salt lanthanum nitrate and 1.55 g of organic ligand dimethylimidazole were ultrasonically dissolved in 10 mL of methanol. 60 The above two solutions were mixed with 0.01 g β-CD and stirred with magnetic force for 30 minutes. Then it was transferred to a 25 mL reactor and placed in a 150 ° C oven for 12 hours. After cooling, the product was centrifuged and washed with anhydrous ethanol three times, and then dried in an oven at 80 ° C for 12 hours to obtain La-MOF@C 60 / β-CD composite materials.

[0042] The prepared La-MOF@C 60The / β-CD composite material was ultrasonically dispersed evenly with DMF to obtain a dispersion. Before modifying the electrode, the glassy carbon electrode was polished with 1.0μm and 0.05μm alumina powders, respectively, and then ultrasonically cleaned in water, ethanol and water in turn. The material dispersion was droplet-coated on the polished glassy carbon electrode surface and dried to obtain La-MOF@C 60 / β-CD / GCE. La-MOF / GCE, β-CD / GCE, and C 60 / GCE and La-MOF@C 60 / GCE.

[0043] The prepared working electrode La-MOF@C 60 / β-CD / GCE, a counter electrode platinum wire and an Ag / AgCl reference electrode were connected to an electrochemical workstation and assembled into an electrochemical sensor.

[0044] The DPV curves of different dichlorophenol concentrations in lake water detected by electrochemical sensors were recorded by an electrochemical workstation, and the current values ​​corresponding to different dichlorophenol concentrations were read and plotted. Figure 6 The current-concentration linear fitting working curve was obtained. The linear detection range was 0.02μM-20μM, and the detection limit was 8.6nM.

[0045] The recovery rate of the sensor in tap water is shown in Table 2. The recovery rate is between 94.3% and 100%, indicating that the sensor has good applicability in lake water.

[0046] Table 2 Recovery rate measurement of dichlorophenol in lake water samples

[0047]

[0048] The description presented in the above exemplary embodiments is only used to illustrate the technical solution of the present invention, and is not intended to be exhaustive, nor is it intended to limit the present invention to the precise form described. Obviously, it is possible for a person of ordinary skill in the art to make many changes and variations based on the above teachings. The exemplary embodiments are selected and described to explain the specific principles of the present invention and its practical application, so that other technicians in the field can easily understand, implement and use the various exemplary embodiments of the present invention and its various selected forms and modified forms. The scope of protection of the present invention is intended to be defined by the attached claims and their equivalent forms.

Claims

1. A RE-MOF@C for the detection of dichlorophenol in water 60 The method for preparing a / β-CD / GCE electrode is characterized in that: Here are the steps: (1)RE-MOF@C 60 Preparation of / β-CD composite materials: rare earth metal salt and organic ligand are ultrasonically dissolved in organic solvents to obtain two solutions; 60 , β-CD and the two solutions were mixed and magnetically stirred; after reacting for a certain time under certain temperature conditions, the reaction was cooled, the product was centrifuged and washed to obtain a precipitate, and then dried to obtain RE-MOF@C 60 / β-CD composites; (2) Preparation of electrochemical sensor: RE-MOF@C 60 The / β-CD composite material is ultrasonically dispersed uniformly with an organic solvent to obtain a dispersion; before modifying the glassy carbon electrode, the glassy carbon electrode is polished with alumina powders with a particle size of 1.0 μm and 0.05 μm, respectively, and then ultrasonically cleaned in water, ethanol and water in turn; the dispersion is droplet-coated on the polished surface of the glassy carbon electrode and dried to obtain RE-MOF@C 60 / β-CD / GCE electrode.

2. The preparation method according to claim 1, characterized in that: In step (1), the rare earth metal salt includes one or a mixture of two or more of rare earth metal nitrates and rare earth metal chlorides.

3. The preparation method according to claim 1, characterized in that: In step (1), the organic ligand includes one or a mixture of two or more of dimethylimidazole, terephthalic acid, aminoterephthalic acid, and dihydroxyterephthalic acid.

4. The preparation method according to claim 1, characterized in that: In steps (1) and (2), the organic solvent includes one or a mixture of two or more of methanol, ethanol, acetonitrile, dichloromethane, dimethyl sulfoxide, toluene, acetone, tetrahydrofuran, isopropanol, n-butanol, and N,N-dimethylformamide.

5. The preparation method according to claim 1, characterized in that: In step (1), the magnetic stirring time is 0.1 to 96 hours.

6. The preparation method according to claim 1, characterized in that: In step (1), the certain temperature is 60 to 250° C., and the certain time is 0.5 to 96 hours.

7. Application of the electrochemical sensor obtained by the preparation method according to any one of claims 1 to 6 for electrochemical detection of dichlorophenol in water, characterized in that: RE-MOF@C 60 / β-CD / GCE were connected to an electrochemical workstation as working electrode, counter electrode and reference electrode and assembled into an electrochemical sensor for electrochemical detection of dichlorophenol in water.

8. The use according to claim 7, characterized in that: The reference electrode is an Ag / AgCl electrode, a saturated calomel electrode or a mercury-mercurous sulfate electrode.

9. The use according to claim 7, characterized in that: The counter electrode comprises a platinum wire or platinum sheet electrode.

10. The use according to claim 7, characterized in that: The water bodies include river water, lake water, well water and tap water.

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